Magnesium(Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical ...Magnesium(Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization(PEO)/polydopamine(PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times(60 s, 120 s) and dopamine concentrations(1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml(120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion resistance.Furthermore, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and biocompatibility could be a promising candidate for degradable magnesium-based implants.展开更多
Oil–water mixing has brought many problems to a society, and it is of great significance to develop a simple, convenient, efficient, and durable separation material to solve the problem of oil–water mixing. In this ...Oil–water mixing has brought many problems to a society, and it is of great significance to develop a simple, convenient, efficient, and durable separation material to solve the problem of oil–water mixing. In this paper, modified cottons were successfully prepared using polydopamine as the in situ mineralization site of TiO_(2) nanoparticles combined with synergistic crosslinking with KH550. A large number of hydrophilic groups endowed the cotton with superhydrophilic ability, which greatly shortened its water spreading time. The prepared modified cotton could be successfully separated from oil and water, and still had a separation efficiency of 99.999% after 50 cycles. In addition, after 24 h immersion in 1 M HCl, NaOH, and NaCl solutions and 50 abrasion experiments, the modified cotton showed excellent oil–water separation ability, and the separation efficiency was above 99.990%. Successfully provided a simple preparation method to prepare high-efficiency and clean cottons for oil–water separation.展开更多
The combination of photothermal therapywith chemotherapy has gradually developed into promising cancer therapy.Here,a synergistic photothermal-chemotherapy nanoplatform based on polydopamine(PDA)-coated gold nanoparti...The combination of photothermal therapywith chemotherapy has gradually developed into promising cancer therapy.Here,a synergistic photothermal-chemotherapy nanoplatform based on polydopamine(PDA)-coated gold nanoparticles(AuNPs)were facilely achieved via the in situ polymerization of dopamine(DA)on the surface of AuNPs.This nanoplatform exhibited augmented photothermal conversion efficiency and enhanced colloidal stability in comparison with uncoated PDA shell AuNPs.The i-motif DNA nanostructure was assembled on PDA-coated AuNPs,which could be transformed into a C-quadruplex structure under an acidic environment,showing a characteristic pH response.The PDA shell served as a linker between the AuNPs and the i-motif DNA nanostructure.To enhance the specific cellular uptake,the AS1411 aptamer was introduced to the DNA nanostructure employed as a targeting ligand.In addition,Dox-loaded NPs(DAu@PDA-AS141)showed the pH/photothermal-responsive release of Dox.The photothermal effect of DAu@PDA-AS141 elicited excellent photothermal performance and efficient cancer cell inhibition under 808 nm near-infrared(NIR)irradiation.Overall,these results demonstrate that the DAu@PDA-AS141 nanoplatform shows great potential in synergistic photothermal-chemotherapy.展开更多
Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to det...Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to detect arginine kinase(AK),one of the major allergens in shellfish.The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite(FAM)to build a fluorescence resonance energy transfer(FRET)system with PDA particles.Polyethylene glycol(PEG)was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences.With the presence of AK,the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles.The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection(LOD)of 0.298μg/mL.The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products,which indicated its high potential in tracing the presence of AK in complex aquatic products.展开更多
[Objectives]The paper was to prepare immunoadjuvant nanoparticles with good photothermal conversion efficiency and to achieve the synergistic antitumor effect of phototherapy and immunotherapy.[Methods]Poly(lactic-co-...[Objectives]The paper was to prepare immunoadjuvant nanoparticles with good photothermal conversion efficiency and to achieve the synergistic antitumor effect of phototherapy and immunotherapy.[Methods]Poly(lactic-co-glycolic acid)(PLGA)nanoparticles of imiquimod(R837)were prepared by emulsified solvent evaporation method.Dopamine was oxidized and self-polymerized to form polydopamine(PDA)under alkaline conditions,which then adhered to the surface of R837-PNPs(PDA-R837-PNPs).Particle size,Zeta potential and photothermal conversion capacity were used as indicators to select the best polymerization conditions.The photothermal conversion properties and photothermal stability of nanoparticles were investigated by near-infrared light(NIR)irradiation;the encapsulation efficiency and drug loading capacity of R837 were determined by HPLC;the cytotoxicity and cellular uptake of PDA-R837-PNPs were preliminarily investigated using 4T1 cells.[Results]PDA-R837-PNPs were prepared successfully.The optimal polymerization conditions were 0.5 mg/mL dopamine,3 h reaction time and 1.8 mg/mL R837-PNPs.The particle size of PDA-R837-PNPs was(186.7±4.81)nm;the PDI was 0.17±0.02;the Zeta potential was(-21.6±0.56)mV;the encapsulation efficiency was(58.02±0.04)%;and the drug loading capacity was(1.42±0.05)%.PDA-R837-PNPs had good photothermal conversion and photothermal stability in vitro.Cell experiments showed that PDA coating could significantly improve the celluar uptake of PNPs without obvious cytotoxicity,and PDA-R837-PNPs could produce heat to effectively kill 4T1 cells after NIR irradiation.[Conclusions]PDA-R837-PNPs have the characteristics of uniform particle size,good photothermal conversion effect and high cellular uptake rate,thus is expected to achieve efficient antitumor photoimmunotherapic effect.展开更多
An ultrasensitive electrochemical sensor based on polydopamine/carboxylic multi-walled carbon nanotubes(MWCNTs à COOH) nanocomposites modified glassy carbon electrode(GCE) was presented in this work, which has be...An ultrasensitive electrochemical sensor based on polydopamine/carboxylic multi-walled carbon nanotubes(MWCNTs à COOH) nanocomposites modified glassy carbon electrode(GCE) was presented in this work, which has been developed for highly selective and highly sensitive determination of an antimicrobial drug, metronidazole. The preparation of polydopamine/MWCNTs–COOH nanocomposites/GCE sensor is simple and possesses high reproducible, where polydopamine can be coated on the surface of MWCNTs–COOH via a simple electropolymerization process. Under optimized conditions, the proposed sensor showed ultrasensitive determination for metronidazole with a wide linear detection range from5 to 5000 mmol/dm^3 and a low detection limit of 0.25 mmol/dm^3(S/N=3). Moreover, the proposed sensor has been successfully applied for the quantitative determination of metronidazole in real drug samples. This work may provide a novel and effective analytical platform for determination of metronidazole in application of real pharmaceutical and biological samples analysis.展开更多
Exosomes derived from mesenchymal stem cells are of therapeutic interest because of their important role in intracellular communication and biological regulation.On the basis of previously studied nerve conduits,we de...Exosomes derived from mesenchymal stem cells are of therapeutic interest because of their important role in intracellular communication and biological regulation.On the basis of previously studied nerve conduits,we designed a polydopamine-modified chitin conduit loaded with mesenchymal stem cell-derived exosomes that release the exosomes in a sustained and stable manner.In vitro experiments revealed that rat mesenchymal stem cell-derived exosomes enhanced Schwann cell proliferation and secretion of neurotrophic and growth factors,increased the expression of Jun and Sox2 genes,decreased the expression of Mbp and Krox20 genes in Schwann cells,and reprogrammed Schwann cells to a repair phenotype.Furthermore,mesenchymal stem cell-derived exosomes promoted neurite growth of dorsal root ganglia.The polydopamine-modified chitin conduits loaded with mesenchymal stem cell-derived exosomes were used to bridge 2 mm rat sciatic nerve defects.Sustained release of exosomes greatly accelerated nerve healing and improved nerve function.These findings confirm that sustained release of mesenchymal stem cell-derived exosomes loaded into polydopamine-modified chitin conduits promotes the functional recovery of injured peripheral nerves.展开更多
The introduction of neurotrophic factors into injured peripheral nerve sites is beneficial to peripheral nerve regeneration.However,neurotrophic facto rs are rapidly degraded in vivo and obstruct axonal regeneration w...The introduction of neurotrophic factors into injured peripheral nerve sites is beneficial to peripheral nerve regeneration.However,neurotrophic facto rs are rapidly degraded in vivo and obstruct axonal regeneration when used at a supraphysiological dose,which limits their clinical benefits.Bioactive mimetic peptides have been developed to be used in place of neurotrophic factors because they have a similar mode of action to the original growth fa ctors and can activate the equivalent receptors but have simplified sequences and structures.In this study,we created polydopamine-modified chitin conduits loaded with brain-derived neurotrophic factor mimetic peptides and vascular endothelial growth fa ctor mimetic peptides(Chi/PDA-Ps).We found that the Chi/PDA-Ps conduits were less cytotoxic in vitro than chitin conduits alone and provided sustained release of functional peptides.In this study,we evaluated the biocompatibility of the Chi/P DA-Ps conduits.Brain-derived neurotrophic factor mimetic peptide and vascular endothelial growth fa ctor mimetic peptide synergistically promoted prolife ration of Schwann cells and secretion of neurotrophic factors by Schwann cells and attachment and migration of endothelial cells in vitro.The Chi/P DA-Ps conduits were used to bridge a 2 mm gap between the nerve stumps in rat models of sciatic nerve injury.We found that the application of Chi/PDA-Ps conduits could improve the motor function of rats and reduce gastrocnemius atrophy.The electrophysiological results and the microstructure of regenerative nerves showed that the nerve conduction function and re myelination was further resto red.These findings suggest that the Chi/PDA-Ps conduits have great potential in peripheral nerve injury repair.展开更多
The use of magnesium alloys,as a biodegradable medical device,is an interesting challenge for the biomaterials field.Its rapid degradation and the release of hydrogen,when exposed to biological fluids,are the main dra...The use of magnesium alloys,as a biodegradable medical device,is an interesting challenge for the biomaterials field.Its rapid degradation and the release of hydrogen,when exposed to biological fluids,are the main drawbacks for clinical applications.In this work,a coating made of polydopamine(PDOPA),is used as an intermediate layer to decrease the degradation rate of AZ31 magnesium alloy/polymeric coating system,when exposed to Hank’s solution.Experimental results highlighted:(i)the formation of a thin PDOPA layer,(ii)an increased adhesion in the organic coating/metallic substrate system,(iii)a decrease of two orders of magnitude of the corrosion rate when the PDOPA film is used together with an external organic coating,(iv)the efficacy in the use of PDODA due to the synergistic effect of both,physical and chemical,interactions between the PDOPA layer and the organic coating.展开更多
Epoxy resin powder coating has been successfully applied on the corrosion protection of magnesium lithium alloys.However,poor wear resistance and microcracks formed during the solidification have limited it extensive ...Epoxy resin powder coating has been successfully applied on the corrosion protection of magnesium lithium alloys.However,poor wear resistance and microcracks formed during the solidification have limited it extensive application.There are limited approaches to exploit such anti-corrosion and mechanical properties of magnesium lithium alloys.Herein,the epoxy resin powder coating with polydopamine modified molybdenum disulfide(MoS_(2)@PDA-EP powder coating with 0,0.1,0.2,0.5,1.0 wt.%loading)was well prepared by melt extrusion to investigate its anticorrosion performance and wear resistance.The results revealed that the addition of MoS_(2)@PDA enhanced the adhesion strength between coatings and alloys,wear resistance and corrosion protection of the powder coatings.Among them,the optimum was obtained by 0.2 wt.%MoS_(2)@PDA-EP powder coating which could be attributed to well dispersion and efficient adhesion with coating matrix.To conclude,MoS_(2)@PDA-EP powder coating is meaningfully beneficial for the anticorrosive and wear performance improvement of magnesium lithium alloys.展开更多
Hydrophilic modification is a promising method to inhibit fouling formation on ultrafiltration membrane.In this work,different mass concentrations(1%–16%)of hydrophilic polyvinylpyrrolidone were incorporated into pol...Hydrophilic modification is a promising method to inhibit fouling formation on ultrafiltration membrane.In this work,different mass concentrations(1%–16%)of hydrophilic polyvinylpyrrolidone were incorporated into polyethersulfone(PES)membranes fabricated by none-solvent induced phase separation.Then,polydopamine(PDA)coating on the surface of prepared membrane was carried out at pH 8.5.The morphology and structure,surface hydrophilicity,permeation flux,BSA rejection,antifouling and stability performances of PES and PDA/PES modified membranes were investigated in detail.The results indicated that PDA was successfully attached onto the membranes.Membrane hydrophilicity was evaluated by water contact angle measurement.The contact angles of modified membranes reduced remarkably,suggesting that the membrane hydrophilicities were significantly increased.The results of filtration tests,which were done by dead-end filtration of bovine serum albumin solution,showed that the properties of permeability and fouling resistance were obviously improved by PDA modification.When polyvinylpyrrolidone mass content reached 10%,flux recovery ratio of modified membrane was up to91.23%,and its BSA rejection were over 70%.The results of stability tests showed that the modified membranes had good mechanical stability and chemical stability.This facile fabrication procedure and outstanding performances suggested that the modified membranes had a potential in treating fouling.展开更多
Magnesium alloys are candidates as biodegradable medical materials due to their biocompatibility and favorable mechanical properties.Unfortunately,the high corrosion rate in physiological media and the release of hydr...Magnesium alloys are candidates as biodegradable medical materials due to their biocompatibility and favorable mechanical properties.Unfortunately,the high corrosion rate in physiological media and the release of hydrogen,limit their widespread use in biomedical applications.In this work,an intermediate coating based on polydopamine(PDOPA),between Mg substrate and an organic coating,was used to decreasing the degradation rate of AZ31 magnesium alloy,during the long-term exposure in simulated body fluid.Electrochemical Impedance Spectroscopy measurements were carried out to study the corrosion resistance of samples.Results demonstrated that the PDOPA interlayer determined the reduction of the substrate degradation rate.The results were interpreted supposing a synergistic effect which occurred when PDOPA and the organic coating were used together.展开更多
Cardiac valve replacement is an effective method to treat valvular heart disease.Artificial valves used routinely in clinic still have defects.In our study,we explored a novel method to modify the performance of Decel...Cardiac valve replacement is an effective method to treat valvular heart disease.Artificial valves used routinely in clinic still have defects.In our study,we explored a novel method to modify the performance of Decellularized Heart Valve(DHV)scaffold.The decellularized porcine aortic valve was prepared using sequential hydrophile and lipophile solubilization method.The sericin was extracted from silk fibroin-deficient silkworm cocoon by lithium bromide method.First,DHV was immersed in sericin solution to produce the sericin–DHV composite scaffold.Then,we modified the DHV by making a Polydopamine(PDA)coating on the DHV first and then binding the sericin.The physical properties and biological compatibility of our composite scaffold were assessed in vitro and in vivo.Sericin were successfully prepared,combined to DHV and improved its biocompatibility.PDA coating further promoted the combination of sericin on DHV and improved the physical properties of scaffolds.The decay rate of our modified valve scaffold was decreased in vivo and it showed good compatibility with blood.In conclusion,our modification improved the physical properties and biocompatibility of the valve scaffold.The combination of PDA and sericin promoted the recellularization of decellularized valves,showing great potential to be a novel artificial valve.展开更多
The development of novel theranostic agents with outstanding diagnostic and therapeutic performances is still strongly desired in the treatment of hepatocellular carcinoma(HCC).Here,a fucoidan-modified mesoporous poly...The development of novel theranostic agents with outstanding diagnostic and therapeutic performances is still strongly desired in the treatment of hepatocellular carcinoma(HCC).Here,a fucoidan-modified mesoporous polydopamine nanoparticle dual-loaded with gadolinium iron and doxorubicin(FMPDA/Gd^(3+)/DOX)was prepared as an effective theranostic agent for magnetic resonance imaging(MRI)-guided chemo-photothermal therapy of HCC.It was found that FMPDA/Gd^(3+)/DOX had a high photothermal conversion efficiency of 33.4%and excellent T1-MRI performance with a longitudinal relaxivity(r1)value of 14.966 m M^(-1)·s^(-1).Moreover,the results suggested that FMPDA/Gd^(3+)/DOX could effectively accumulate into the tumor foci by dual-targeting the tumor-infiltrated platelets and HCC cells,which resulted from the specific interaction between fucoidan and overexpressed p-selectin receptors.The excellent tumor-homing ability and MRI-guided chemo-photothermal therapy therefore endowed FMPDA/Gd^(3+)/DOX with a strongest ability to inhibit tumor growth than the respective single treatment modality.Overall,our study demonstrated that FMPDA/Gd^(3+)/DOX could be applied as a potential nanoplatform for safe and effective cancer theranostics.展开更多
In order to improve the water permeability of poly(vinylidene fluoride)(PVDF)ultrafiltration(UF)membranes with low molecular weight cut-off(MWCO),polydopamine(PDA)was employed in the membrane preparation process.Owing...In order to improve the water permeability of poly(vinylidene fluoride)(PVDF)ultrafiltration(UF)membranes with low molecular weight cut-off(MWCO),polydopamine(PDA)was employed in the membrane preparation process.Owing to itsmerits of material-independent adhesion,PDAwas coated on inorganic particles or added in coagulation bath to tailor the final membrane structure and property.The introduction of PDA broke through the permeability/selectivity trade-off of the PVDF membrane.By adding the PDA coated titaniumdioxide(PDA/TiO2)nanoparticles,water flux increased by 287% while MWCO kept similar with the pristine PVDF membrane.Thermodynamics and Kinetics of the PVDF/additives/non-solvent were analyzed and shown that nanoparticles reduced the thermodynamic stability and increased the phase separation speed,and the speed can be adjusted using different nanoparticles.Additionally,X-ray diffraction(XRD)test indicated that PVDF crystalline form changed fromαphase to β phase after adding different nanoparticles.Permeability/selectivity trade-offwas broken through by DA addition in coagulation bath.Compared with the original PVDF membrane,when the DA concentration of the coagulation bath was 2.0 g·L^−1,water flux increased by 312%,and MWCO of the PVDF membrane ranged in 10,000 to 20,000 Da as well as contact angle decreased from 81.4°to 45°.展开更多
Our study producted Polydopamine modified gold nanoflowers with controlled morphology for anti-tumor photothermal therapy.The branch structure containsabundant(Au NFs).By adjusting the reduction rate,the dosage of red...Our study producted Polydopamine modified gold nanoflowers with controlled morphology for anti-tumor photothermal therapy.The branch structure containsabundant(Au NFs).By adjusting the reduction rate,the dosage of reducing agent(sodium borohydride)and the reduction temperature,we can adjust tthe morphology and particle size of Au NFs.We found that the lower reaction temperature is,the more abundant the surface branching structure of gold nanoflowers is,by adjusting the reaction temperature.and the largest specific surface area of golden nanopowder was found at 0℃.The results of TEM indicated that with the increase of sodium borohydride,the diameter of gold nano flowers gold nanoflowers decreased and was in the range of 60~100nm,and it has good EPR effect After that,we modify poly(dopamine)(PDA)biomimetic layer on the surface of golden nanoparticles to obtain Au NFS@PDA.Poly(dopamine)has the ability,of photothermal conversion,which can enhance the plasma resonance ability and biocompatibility of gold nanoflowers in the near infrared region.We can control the thickness of polydopamine layer on the surface of gold nanoflowers between 7~15nm by adjusting dopamine DA concentrationgold nanoflowers.Au NFS@PDA was characterized by its morphology and physical properties.We detect(UV-Vis)spectra in the near infrared region.And it showed obvious absorption peaks in the near infrared region of 575~650nm.Under the 808nm irradiation laser,the photothermal conversion of gold nanoflowers and polydopamine can be rapidly increased to 57°C.Fourier Transform Infrared Absorption Spectroscopy(FTIR)and X-ray Diffraction(XRD)analysis showed that polydopamine was modified successfully,Au NFS@PDA and Au NFs had no obvious difference in crystal form.The cell viability test showed that the bionic Au NFS@PDA had good biocompatibility and showed good antitumor activity against HeLa cells under NIR irradiation.The cell viability was only 12%.Therefore,we can use Au NFS@PDA with good biocompatibility as a promising photothermal conversion agent in tumor therapy.展开更多
Melanin is a biopolymer implicated in the protection of cellular membranes and DNA produced by melanocytes. This pigment has a dual role and should be considered as a photo-protector and as a photosensitizer due to it...Melanin is a biopolymer implicated in the protection of cellular membranes and DNA produced by melanocytes. This pigment has a dual role and should be considered as a photo-protector and as a photosensitizer due to its interaction with UV. The design of multifunctional and biologically responsive coatings is of major interest in modern biomaterials science. The aim of this study is not only to characterize the deposition of multilayered polyelectrolytes films made from polydopamine particles and polyamines like poly-(L-lysine hydrobromide) (PLL), but also to evaluate melanoma cells activity in terms of proliferation and their capacity to stimulate melanin secretion. One could expect that the presence of a melanin like material in the film may have a positive or a negative feedback on the melanin biosynthesis and consequently on melanoma development. Some comparisons are also done with pure polydopamine grains in suspension in the cell culture medium, to investigate if the immobilization of the polydopamine grains has an influence on their bioactivity.展开更多
Diaphragm repair after congenital diaphragmatic hernia is associated with hernia recurrence due to prosthesis failure. Expanded polytetrafluoroethylene (e-PTFE), a synthetic non-degradable biomaterial, is currently us...Diaphragm repair after congenital diaphragmatic hernia is associated with hernia recurrence due to prosthesis failure. Expanded polytetrafluoroethylene (e-PTFE), a synthetic non-degradable biomaterial, is currently used for those diaphragmatic defect repairs. The drawback of e-PTFE is its poor wettability that leads to coating difficulties, bonding that could favor implant integration. However, polydopamine (PDA) can be deposited as well on organic as on inorganic substrates. Therefore, we assessed the biological responses of a clinically used e-PTFE biomaterial treated with PDA in two different manners: one impregnated with PDA and the other coated with a one side PDA film. Mechanical properties of the raw e-PTFE, the PDA soaked biomaterial and the PDA coated surface were characterized by colloidal probe atomic force microscopy. Behaviors of primary human fibroblasts and Wharton’s jelly stem cells were investigated by electron microscopy. Findings reveal that the mechanical properties at the microscopic scale are not modified by the PDA treatments. Cells spread onto both PDA functionalized substrates. In addition, microscopic observations disclose numerous focal cell contacts, evidencing cell attachment, and cytoplasmic projections particularly with the nanoscale PDA coating. Results clearly suggest that PDA in general but above all the PDA coating enhance cellular colonization of the implant material.展开更多
This paper aims to investigate the water absorption of wood flour/polypropylene composites and its effects on dimensional stability and crystallization properties. Wood-plastic composites (WPCs) makes using polydopami...This paper aims to investigate the water absorption of wood flour/polypropylene composites and its effects on dimensional stability and crystallization properties. Wood-plastic composites (WPCs) makes using polydopamine modified wood flour (WF-D), virgin polypropylene, maleic anhydride-grafted polypropylene (MA) and antioxidant, by using hot-pressing moulding. Water absorption (WA), thickness swelling (TS) and failure of flexural properties of the composites have studied for a range of immersion times. It is found that the WA and TS have increased with WF content and immersion time. The water absorption and thickness swelling of WPCs are 0.85% and 0.99%, respectively, after 8 days immersion. With the prolonging of immersion time, the impact strength, flexural strength and flexural modulus of WPCs increase first and then decrease. The impact strength decreases from 3.32 kJ/m<sup>2</sup> to 2.94 kJ/m<sup>2</sup>, the retention rate is 88.55%;the flexural strength and flexural modulus by 68.58 Mpa and 3.92 Gpa, respectively. WPCs crystallization and thermal properties decrease slightly. Microstructures of the composites are examined to understand the mechanisms for the wood-plastic interaction which affects the water absorption and thickness swelling. Our work demonstrates that using polydopamine treatment wood flour for preparing WPCs can be an efficient way to improve the water resistance of WPCs.展开更多
To fabricate polydopamine-sensitized solar cells with improved solar power conversion efficiency, the effects of pH, buffer, adsorption time and electrode potential for the electrochemical oxidation and polymerization...To fabricate polydopamine-sensitized solar cells with improved solar power conversion efficiency, the effects of pH, buffer, adsorption time and electrode potential for the electrochemical oxidation and polymerization of dopamine on TiO<sub>2</sub> film were investigated. The optimum pH was around 7. It was found that the use of a buffer, especially 2-(N-morpholino)ethanesulfonic acid, significantly deteriorated the electrochemical adsorption of polydopamine, and the highest solar power conversion efficiency was obtained without buffer. With increasing adsorption time, the amount of adsorbed polydopamine increased but the solar power conversion efficiency decreased, suggesting the increased resistivity of polydopamine with a larger degree of polymerization. It was suggested that the reversal of electrode potential from positive to negative would be essential for the electrochemical adsorption of polydopamine.展开更多
文摘Magnesium(Mg) alloys are well-known in biomedical materials owing to their elastic module near to bone, biocompatibility and biodegradation properties. Nevertheless, poor corrosion resistance hinders their biomedical applications. Besides, it is necessary to endow Mg alloys with bioactive property, which is crucial for temporary bone implants. Here, a self-healing, corrosion resistant and bioactive duplex coating of plasma electrolytic oxidization(PEO)/polydopamine(PDA) is applied on AZ91 substrate using PEO and subsequent electrodeposition process. Moreover, the role of different electrodeposition times(60 s, 120 s) and dopamine concentrations(1 and 1.5 mg/ml) to improve corrosion resistance, bioactivity, biocompatibility and self-healing property and its mechanism are investigated. The results indicate that the PEO coating is efficiently sealed by the PDA, depending on the electrodeposition parameters. Noticeably, electrodeposition for 120 s in dopamine concentration of 1 mg/ml(120T-1C) results in the formation of uniform and crack-free PDA coating. Duplex PEO/PDA coatings reveal high bioactivity compared to PEO coating, owing to electrostatic interaction between PDA top-layer and calcium and phosphate ions as well as high hydrophilicity of coatings. In addition, duplex PEO/PDA coatings also show improved and more stable protective performance than the PEO and bare alloy, depending on the PDA deposition parameters. Noticeably, the corrosion current density of the 120T-1C decreases one orders of magnitude compared to PEO. In addition, the presence of a broad passivation region in the anodic polarization branch shows durable self-healing property via Zipper-like mechanism, demonstrating the duplex coating could preserve promising corrosion resistance.Furthermore, the cytocompatibility of duplex coated samples is also confirmed via interaction with MG63 cells. In summary, the PEO/PDA coating with great corrosion protection, self-healing ability, bioactivity and biocompatibility could be a promising candidate for degradable magnesium-based implants.
基金supported by the National Natural Science Foundation of China(no.51735013).
文摘Oil–water mixing has brought many problems to a society, and it is of great significance to develop a simple, convenient, efficient, and durable separation material to solve the problem of oil–water mixing. In this paper, modified cottons were successfully prepared using polydopamine as the in situ mineralization site of TiO_(2) nanoparticles combined with synergistic crosslinking with KH550. A large number of hydrophilic groups endowed the cotton with superhydrophilic ability, which greatly shortened its water spreading time. The prepared modified cotton could be successfully separated from oil and water, and still had a separation efficiency of 99.999% after 50 cycles. In addition, after 24 h immersion in 1 M HCl, NaOH, and NaCl solutions and 50 abrasion experiments, the modified cotton showed excellent oil–water separation ability, and the separation efficiency was above 99.990%. Successfully provided a simple preparation method to prepare high-efficiency and clean cottons for oil–water separation.
基金This work was financially supported by National Natural Sciences Foundation of China(31971308 and 82102767)National S&T Major Project(2019ZX09301-147)+1 种基金Sichuan Science and Technology Program(2021YFS0081)Luzhou Science and Technology Plan(2018CDLZ-10).
文摘The combination of photothermal therapywith chemotherapy has gradually developed into promising cancer therapy.Here,a synergistic photothermal-chemotherapy nanoplatform based on polydopamine(PDA)-coated gold nanoparticles(AuNPs)were facilely achieved via the in situ polymerization of dopamine(DA)on the surface of AuNPs.This nanoplatform exhibited augmented photothermal conversion efficiency and enhanced colloidal stability in comparison with uncoated PDA shell AuNPs.The i-motif DNA nanostructure was assembled on PDA-coated AuNPs,which could be transformed into a C-quadruplex structure under an acidic environment,showing a characteristic pH response.The PDA shell served as a linker between the AuNPs and the i-motif DNA nanostructure.To enhance the specific cellular uptake,the AS1411 aptamer was introduced to the DNA nanostructure employed as a targeting ligand.In addition,Dox-loaded NPs(DAu@PDA-AS141)showed the pH/photothermal-responsive release of Dox.The photothermal effect of DAu@PDA-AS141 elicited excellent photothermal performance and efficient cancer cell inhibition under 808 nm near-infrared(NIR)irradiation.Overall,these results demonstrate that the DAu@PDA-AS141 nanoplatform shows great potential in synergistic photothermal-chemotherapy.
基金financially supported by the National Key R&D Program of China(2019YFC1605002)the National Natural Science Foundation of China(31871735)Xinmiao Talent Project of Zhejiang Province(2019R408063)。
文摘Simple yet efficient detection methods for food allergens are in urgent need to help people avoid the risks imposed by allergenic food.In this work,a polydopamine(PDA)-based fluorescent aptasensor was developed to detect arginine kinase(AK),one of the major allergens in shellfish.The aptamer towards AK was firstly selected via systematic evolution of ligands by exponential enrichment method and labeled with fluorescein amidite(FAM)to build a fluorescence resonance energy transfer(FRET)system with PDA particles.Polyethylene glycol(PEG)was employed to construct an antifouling surface for the aptasensor to eliminate food matrix interferences.With the presence of AK,the PDA-based aptasensor exhibited elevated fluorescent signals as the FAM-labeled aptamer bound to AK and detached from the PDA particles.The aptasensor showed great stability and resistance to nonspecific interference of background proteins and had a limit of detection(LOD)of 0.298μg/mL.The proposed aptasensor was further proved to be feasible for quantitative analysis of AK in nine species of shrimps and five commercial processed products,which indicated its high potential in tracing the presence of AK in complex aquatic products.
基金Supported by National Natural Science Foundation of China(82003683)Fundamental Research Funds for the Central Universities of Southwest Minzu University(2021105)。
文摘[Objectives]The paper was to prepare immunoadjuvant nanoparticles with good photothermal conversion efficiency and to achieve the synergistic antitumor effect of phototherapy and immunotherapy.[Methods]Poly(lactic-co-glycolic acid)(PLGA)nanoparticles of imiquimod(R837)were prepared by emulsified solvent evaporation method.Dopamine was oxidized and self-polymerized to form polydopamine(PDA)under alkaline conditions,which then adhered to the surface of R837-PNPs(PDA-R837-PNPs).Particle size,Zeta potential and photothermal conversion capacity were used as indicators to select the best polymerization conditions.The photothermal conversion properties and photothermal stability of nanoparticles were investigated by near-infrared light(NIR)irradiation;the encapsulation efficiency and drug loading capacity of R837 were determined by HPLC;the cytotoxicity and cellular uptake of PDA-R837-PNPs were preliminarily investigated using 4T1 cells.[Results]PDA-R837-PNPs were prepared successfully.The optimal polymerization conditions were 0.5 mg/mL dopamine,3 h reaction time and 1.8 mg/mL R837-PNPs.The particle size of PDA-R837-PNPs was(186.7±4.81)nm;the PDI was 0.17±0.02;the Zeta potential was(-21.6±0.56)mV;the encapsulation efficiency was(58.02±0.04)%;and the drug loading capacity was(1.42±0.05)%.PDA-R837-PNPs had good photothermal conversion and photothermal stability in vitro.Cell experiments showed that PDA coating could significantly improve the celluar uptake of PNPs without obvious cytotoxicity,and PDA-R837-PNPs could produce heat to effectively kill 4T1 cells after NIR irradiation.[Conclusions]PDA-R837-PNPs have the characteristics of uniform particle size,good photothermal conversion effect and high cellular uptake rate,thus is expected to achieve efficient antitumor photoimmunotherapic effect.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.21475046,21427809)
文摘An ultrasensitive electrochemical sensor based on polydopamine/carboxylic multi-walled carbon nanotubes(MWCNTs à COOH) nanocomposites modified glassy carbon electrode(GCE) was presented in this work, which has been developed for highly selective and highly sensitive determination of an antimicrobial drug, metronidazole. The preparation of polydopamine/MWCNTs–COOH nanocomposites/GCE sensor is simple and possesses high reproducible, where polydopamine can be coated on the surface of MWCNTs–COOH via a simple electropolymerization process. Under optimized conditions, the proposed sensor showed ultrasensitive determination for metronidazole with a wide linear detection range from5 to 5000 mmol/dm^3 and a low detection limit of 0.25 mmol/dm^3(S/N=3). Moreover, the proposed sensor has been successfully applied for the quantitative determination of metronidazole in real drug samples. This work may provide a novel and effective analytical platform for determination of metronidazole in application of real pharmaceutical and biological samples analysis.
基金supported by the National Natural Science Foundation of China,Nos.31771322,31571235the National Science Foundation of Beijing,No.7212121+3 种基金Beijing Science Technology New Star Cross Subject,No.2018019Science and Technology Plan Project of Shenzhen,No.JCYJ 20190806162205278the Key Laboratory of Trauma and Neural Regeneration(Peking University),Ministry of Educationa grant from National Center for Trauma Medicine,No.BMU2020XY005-01(all to PXZ).
文摘Exosomes derived from mesenchymal stem cells are of therapeutic interest because of their important role in intracellular communication and biological regulation.On the basis of previously studied nerve conduits,we designed a polydopamine-modified chitin conduit loaded with mesenchymal stem cell-derived exosomes that release the exosomes in a sustained and stable manner.In vitro experiments revealed that rat mesenchymal stem cell-derived exosomes enhanced Schwann cell proliferation and secretion of neurotrophic and growth factors,increased the expression of Jun and Sox2 genes,decreased the expression of Mbp and Krox20 genes in Schwann cells,and reprogrammed Schwann cells to a repair phenotype.Furthermore,mesenchymal stem cell-derived exosomes promoted neurite growth of dorsal root ganglia.The polydopamine-modified chitin conduits loaded with mesenchymal stem cell-derived exosomes were used to bridge 2 mm rat sciatic nerve defects.Sustained release of exosomes greatly accelerated nerve healing and improved nerve function.These findings confirm that sustained release of mesenchymal stem cell-derived exosomes loaded into polydopamine-modified chitin conduits promotes the functional recovery of injured peripheral nerves.
基金the National Natural Science Foundation of China,Nos.31771322,31571235the Natural Science Foundation of Beijing,No.7212121+3 种基金Beijing Science Technology New Star Cross Subject of China,No.2018019Shenzhen Science and Technology Plan Project of China,No.JCYJ 20190806162205278the Key Laboratory of Trauma and Neural Regeneration(Peking University),Ministry of Educationa grant from National Center for Trauma Medicine,No.BMU2020XY005-01(all to PXZ)。
文摘The introduction of neurotrophic factors into injured peripheral nerve sites is beneficial to peripheral nerve regeneration.However,neurotrophic facto rs are rapidly degraded in vivo and obstruct axonal regeneration when used at a supraphysiological dose,which limits their clinical benefits.Bioactive mimetic peptides have been developed to be used in place of neurotrophic factors because they have a similar mode of action to the original growth fa ctors and can activate the equivalent receptors but have simplified sequences and structures.In this study,we created polydopamine-modified chitin conduits loaded with brain-derived neurotrophic factor mimetic peptides and vascular endothelial growth fa ctor mimetic peptides(Chi/PDA-Ps).We found that the Chi/PDA-Ps conduits were less cytotoxic in vitro than chitin conduits alone and provided sustained release of functional peptides.In this study,we evaluated the biocompatibility of the Chi/P DA-Ps conduits.Brain-derived neurotrophic factor mimetic peptide and vascular endothelial growth fa ctor mimetic peptide synergistically promoted prolife ration of Schwann cells and secretion of neurotrophic factors by Schwann cells and attachment and migration of endothelial cells in vitro.The Chi/P DA-Ps conduits were used to bridge a 2 mm gap between the nerve stumps in rat models of sciatic nerve injury.We found that the application of Chi/PDA-Ps conduits could improve the motor function of rats and reduce gastrocnemius atrophy.The electrophysiological results and the microstructure of regenerative nerves showed that the nerve conduction function and re myelination was further resto red.These findings suggest that the Chi/PDA-Ps conduits have great potential in peripheral nerve injury repair.
文摘The use of magnesium alloys,as a biodegradable medical device,is an interesting challenge for the biomaterials field.Its rapid degradation and the release of hydrogen,when exposed to biological fluids,are the main drawbacks for clinical applications.In this work,a coating made of polydopamine(PDOPA),is used as an intermediate layer to decrease the degradation rate of AZ31 magnesium alloy/polymeric coating system,when exposed to Hank’s solution.Experimental results highlighted:(i)the formation of a thin PDOPA layer,(ii)an increased adhesion in the organic coating/metallic substrate system,(iii)a decrease of two orders of magnitude of the corrosion rate when the PDOPA film is used together with an external organic coating,(iv)the efficacy in the use of PDODA due to the synergistic effect of both,physical and chemical,interactions between the PDOPA layer and the organic coating.
基金financial support provided by the National Natural Science Foundation of China(Grant No.U1806225)the National Natural Science Foundation of China(Grant No.51908092)the Joint Funds of the National Natural Science Foundation of China-Guangdong(Grant No.U1801254)。
文摘Epoxy resin powder coating has been successfully applied on the corrosion protection of magnesium lithium alloys.However,poor wear resistance and microcracks formed during the solidification have limited it extensive application.There are limited approaches to exploit such anti-corrosion and mechanical properties of magnesium lithium alloys.Herein,the epoxy resin powder coating with polydopamine modified molybdenum disulfide(MoS_(2)@PDA-EP powder coating with 0,0.1,0.2,0.5,1.0 wt.%loading)was well prepared by melt extrusion to investigate its anticorrosion performance and wear resistance.The results revealed that the addition of MoS_(2)@PDA enhanced the adhesion strength between coatings and alloys,wear resistance and corrosion protection of the powder coatings.Among them,the optimum was obtained by 0.2 wt.%MoS_(2)@PDA-EP powder coating which could be attributed to well dispersion and efficient adhesion with coating matrix.To conclude,MoS_(2)@PDA-EP powder coating is meaningfully beneficial for the anticorrosive and wear performance improvement of magnesium lithium alloys.
基金supported by the National Natural Science Foundation of China(Nos.51573041,21776067)the Demonstration Base Project of University-Enterprise Cooperation of Hunan Province(No.145812)。
文摘Hydrophilic modification is a promising method to inhibit fouling formation on ultrafiltration membrane.In this work,different mass concentrations(1%–16%)of hydrophilic polyvinylpyrrolidone were incorporated into polyethersulfone(PES)membranes fabricated by none-solvent induced phase separation.Then,polydopamine(PDA)coating on the surface of prepared membrane was carried out at pH 8.5.The morphology and structure,surface hydrophilicity,permeation flux,BSA rejection,antifouling and stability performances of PES and PDA/PES modified membranes were investigated in detail.The results indicated that PDA was successfully attached onto the membranes.Membrane hydrophilicity was evaluated by water contact angle measurement.The contact angles of modified membranes reduced remarkably,suggesting that the membrane hydrophilicities were significantly increased.The results of filtration tests,which were done by dead-end filtration of bovine serum albumin solution,showed that the properties of permeability and fouling resistance were obviously improved by PDA modification.When polyvinylpyrrolidone mass content reached 10%,flux recovery ratio of modified membrane was up to91.23%,and its BSA rejection were over 70%.The results of stability tests showed that the modified membranes had good mechanical stability and chemical stability.This facile fabrication procedure and outstanding performances suggested that the modified membranes had a potential in treating fouling.
文摘Magnesium alloys are candidates as biodegradable medical materials due to their biocompatibility and favorable mechanical properties.Unfortunately,the high corrosion rate in physiological media and the release of hydrogen,limit their widespread use in biomedical applications.In this work,an intermediate coating based on polydopamine(PDOPA),between Mg substrate and an organic coating,was used to decreasing the degradation rate of AZ31 magnesium alloy,during the long-term exposure in simulated body fluid.Electrochemical Impedance Spectroscopy measurements were carried out to study the corrosion resistance of samples.Results demonstrated that the PDOPA interlayer determined the reduction of the substrate degradation rate.The results were interpreted supposing a synergistic effect which occurred when PDOPA and the organic coating were used together.
基金supported by the National Key Research and Development Program of China Stem Cell and Translational Research(2016YFA0101103)the National Natural Science Foundation of China(grant numbers 81930052,81901904,82000367,82001701).
文摘Cardiac valve replacement is an effective method to treat valvular heart disease.Artificial valves used routinely in clinic still have defects.In our study,we explored a novel method to modify the performance of Decellularized Heart Valve(DHV)scaffold.The decellularized porcine aortic valve was prepared using sequential hydrophile and lipophile solubilization method.The sericin was extracted from silk fibroin-deficient silkworm cocoon by lithium bromide method.First,DHV was immersed in sericin solution to produce the sericin–DHV composite scaffold.Then,we modified the DHV by making a Polydopamine(PDA)coating on the DHV first and then binding the sericin.The physical properties and biological compatibility of our composite scaffold were assessed in vitro and in vivo.Sericin were successfully prepared,combined to DHV and improved its biocompatibility.PDA coating further promoted the combination of sericin on DHV and improved the physical properties of scaffolds.The decay rate of our modified valve scaffold was decreased in vivo and it showed good compatibility with blood.In conclusion,our modification improved the physical properties and biocompatibility of the valve scaffold.The combination of PDA and sericin promoted the recellularization of decellularized valves,showing great potential to be a novel artificial valve.
基金supported by the National Key Research and Development projects intergovernmental cooperation in science and technology of China(2018YFE0126900)National Natural Science Foundation of China(82072025 and82072026)+2 种基金Zhejiang Provincial Natural Science Foundation(LQ21H180003)Key R&D Program of Lishui City(2021ZDYF12)Medical Health Science and Technology Project of Zhejiang Provincial Health Commission(2022RC088)。
文摘The development of novel theranostic agents with outstanding diagnostic and therapeutic performances is still strongly desired in the treatment of hepatocellular carcinoma(HCC).Here,a fucoidan-modified mesoporous polydopamine nanoparticle dual-loaded with gadolinium iron and doxorubicin(FMPDA/Gd^(3+)/DOX)was prepared as an effective theranostic agent for magnetic resonance imaging(MRI)-guided chemo-photothermal therapy of HCC.It was found that FMPDA/Gd^(3+)/DOX had a high photothermal conversion efficiency of 33.4%and excellent T1-MRI performance with a longitudinal relaxivity(r1)value of 14.966 m M^(-1)·s^(-1).Moreover,the results suggested that FMPDA/Gd^(3+)/DOX could effectively accumulate into the tumor foci by dual-targeting the tumor-infiltrated platelets and HCC cells,which resulted from the specific interaction between fucoidan and overexpressed p-selectin receptors.The excellent tumor-homing ability and MRI-guided chemo-photothermal therapy therefore endowed FMPDA/Gd^(3+)/DOX with a strongest ability to inhibit tumor growth than the respective single treatment modality.Overall,our study demonstrated that FMPDA/Gd^(3+)/DOX could be applied as a potential nanoplatform for safe and effective cancer theranostics.
基金the financial support from National Key R&D Program of China(2017YFD0400402)National Natural Science Foundation of China(No.21576132).
文摘In order to improve the water permeability of poly(vinylidene fluoride)(PVDF)ultrafiltration(UF)membranes with low molecular weight cut-off(MWCO),polydopamine(PDA)was employed in the membrane preparation process.Owing to itsmerits of material-independent adhesion,PDAwas coated on inorganic particles or added in coagulation bath to tailor the final membrane structure and property.The introduction of PDA broke through the permeability/selectivity trade-off of the PVDF membrane.By adding the PDA coated titaniumdioxide(PDA/TiO2)nanoparticles,water flux increased by 287% while MWCO kept similar with the pristine PVDF membrane.Thermodynamics and Kinetics of the PVDF/additives/non-solvent were analyzed and shown that nanoparticles reduced the thermodynamic stability and increased the phase separation speed,and the speed can be adjusted using different nanoparticles.Additionally,X-ray diffraction(XRD)test indicated that PVDF crystalline form changed fromαphase to β phase after adding different nanoparticles.Permeability/selectivity trade-offwas broken through by DA addition in coagulation bath.Compared with the original PVDF membrane,when the DA concentration of the coagulation bath was 2.0 g·L^−1,water flux increased by 312%,and MWCO of the PVDF membrane ranged in 10,000 to 20,000 Da as well as contact angle decreased from 81.4°to 45°.
文摘Our study producted Polydopamine modified gold nanoflowers with controlled morphology for anti-tumor photothermal therapy.The branch structure containsabundant(Au NFs).By adjusting the reduction rate,the dosage of reducing agent(sodium borohydride)and the reduction temperature,we can adjust tthe morphology and particle size of Au NFs.We found that the lower reaction temperature is,the more abundant the surface branching structure of gold nanoflowers is,by adjusting the reaction temperature.and the largest specific surface area of golden nanopowder was found at 0℃.The results of TEM indicated that with the increase of sodium borohydride,the diameter of gold nano flowers gold nanoflowers decreased and was in the range of 60~100nm,and it has good EPR effect After that,we modify poly(dopamine)(PDA)biomimetic layer on the surface of golden nanoparticles to obtain Au NFS@PDA.Poly(dopamine)has the ability,of photothermal conversion,which can enhance the plasma resonance ability and biocompatibility of gold nanoflowers in the near infrared region.We can control the thickness of polydopamine layer on the surface of gold nanoflowers between 7~15nm by adjusting dopamine DA concentrationgold nanoflowers.Au NFS@PDA was characterized by its morphology and physical properties.We detect(UV-Vis)spectra in the near infrared region.And it showed obvious absorption peaks in the near infrared region of 575~650nm.Under the 808nm irradiation laser,the photothermal conversion of gold nanoflowers and polydopamine can be rapidly increased to 57°C.Fourier Transform Infrared Absorption Spectroscopy(FTIR)and X-ray Diffraction(XRD)analysis showed that polydopamine was modified successfully,Au NFS@PDA and Au NFs had no obvious difference in crystal form.The cell viability test showed that the bionic Au NFS@PDA had good biocompatibility and showed good antitumor activity against HeLa cells under NIR irradiation.The cell viability was only 12%.Therefore,we can use Au NFS@PDA with good biocompatibility as a promising photothermal conversion agent in tumor therapy.
文摘Melanin is a biopolymer implicated in the protection of cellular membranes and DNA produced by melanocytes. This pigment has a dual role and should be considered as a photo-protector and as a photosensitizer due to its interaction with UV. The design of multifunctional and biologically responsive coatings is of major interest in modern biomaterials science. The aim of this study is not only to characterize the deposition of multilayered polyelectrolytes films made from polydopamine particles and polyamines like poly-(L-lysine hydrobromide) (PLL), but also to evaluate melanoma cells activity in terms of proliferation and their capacity to stimulate melanin secretion. One could expect that the presence of a melanin like material in the film may have a positive or a negative feedback on the melanin biosynthesis and consequently on melanoma development. Some comparisons are also done with pure polydopamine grains in suspension in the cell culture medium, to investigate if the immobilization of the polydopamine grains has an influence on their bioactivity.
文摘Diaphragm repair after congenital diaphragmatic hernia is associated with hernia recurrence due to prosthesis failure. Expanded polytetrafluoroethylene (e-PTFE), a synthetic non-degradable biomaterial, is currently used for those diaphragmatic defect repairs. The drawback of e-PTFE is its poor wettability that leads to coating difficulties, bonding that could favor implant integration. However, polydopamine (PDA) can be deposited as well on organic as on inorganic substrates. Therefore, we assessed the biological responses of a clinically used e-PTFE biomaterial treated with PDA in two different manners: one impregnated with PDA and the other coated with a one side PDA film. Mechanical properties of the raw e-PTFE, the PDA soaked biomaterial and the PDA coated surface were characterized by colloidal probe atomic force microscopy. Behaviors of primary human fibroblasts and Wharton’s jelly stem cells were investigated by electron microscopy. Findings reveal that the mechanical properties at the microscopic scale are not modified by the PDA treatments. Cells spread onto both PDA functionalized substrates. In addition, microscopic observations disclose numerous focal cell contacts, evidencing cell attachment, and cytoplasmic projections particularly with the nanoscale PDA coating. Results clearly suggest that PDA in general but above all the PDA coating enhance cellular colonization of the implant material.
文摘This paper aims to investigate the water absorption of wood flour/polypropylene composites and its effects on dimensional stability and crystallization properties. Wood-plastic composites (WPCs) makes using polydopamine modified wood flour (WF-D), virgin polypropylene, maleic anhydride-grafted polypropylene (MA) and antioxidant, by using hot-pressing moulding. Water absorption (WA), thickness swelling (TS) and failure of flexural properties of the composites have studied for a range of immersion times. It is found that the WA and TS have increased with WF content and immersion time. The water absorption and thickness swelling of WPCs are 0.85% and 0.99%, respectively, after 8 days immersion. With the prolonging of immersion time, the impact strength, flexural strength and flexural modulus of WPCs increase first and then decrease. The impact strength decreases from 3.32 kJ/m<sup>2</sup> to 2.94 kJ/m<sup>2</sup>, the retention rate is 88.55%;the flexural strength and flexural modulus by 68.58 Mpa and 3.92 Gpa, respectively. WPCs crystallization and thermal properties decrease slightly. Microstructures of the composites are examined to understand the mechanisms for the wood-plastic interaction which affects the water absorption and thickness swelling. Our work demonstrates that using polydopamine treatment wood flour for preparing WPCs can be an efficient way to improve the water resistance of WPCs.
文摘To fabricate polydopamine-sensitized solar cells with improved solar power conversion efficiency, the effects of pH, buffer, adsorption time and electrode potential for the electrochemical oxidation and polymerization of dopamine on TiO<sub>2</sub> film were investigated. The optimum pH was around 7. It was found that the use of a buffer, especially 2-(N-morpholino)ethanesulfonic acid, significantly deteriorated the electrochemical adsorption of polydopamine, and the highest solar power conversion efficiency was obtained without buffer. With increasing adsorption time, the amount of adsorbed polydopamine increased but the solar power conversion efficiency decreased, suggesting the increased resistivity of polydopamine with a larger degree of polymerization. It was suggested that the reversal of electrode potential from positive to negative would be essential for the electrochemical adsorption of polydopamine.
