Sensitive monitoring of the target products during the biosynthesis process is crucial,and facile analytical approaches are urgently needed.Herein,phosphatidylserine(PS)was chosen as the model target,a colorimetric ap...Sensitive monitoring of the target products during the biosynthesis process is crucial,and facile analytical approaches are urgently needed.Herein,phosphatidylserine(PS)was chosen as the model target,a colorimetric aptasensor was developed for the rapid quantitation in biosynthesis samples.A chimeric aptamer was constructed with two homogeneous original PS aptamers.Specific recognition between the chimeric aptamer and PS results in the desorption of aptamer from the surface of the AuNPs nanozyme,and the peroxidase-like enzymatic activity of the AuNPs nanozyme was weakened in a relationship with the different concentrations.The developed aptasensor performed well when applied for analyzing PS in biosynthesis samples.The aptasensor offers good sensitivity and selectivity,under optimal conditions,achieving monitoring and quantitation of PS in the range of 2.5-80.0μmol/L,with a limit of detection at 536.2 nmol/L.Moreover,the aptasensor provides good accuracy,with comparison rates of 98.17%-106.40%,when compared with the HPLC-ELSD.This study provides a good reference for monitoring other biosynthesized products and promoting the development of aptamers and aptasensors in real-world applications.展开更多
Norovirus(NoV)is regarded as one of the most common causes of foodborne diarrhea in the world.It is urgent to identify the pathogenic microorganism of the diarrhea in short time.In this work,we developed an electroche...Norovirus(NoV)is regarded as one of the most common causes of foodborne diarrhea in the world.It is urgent to identify the pathogenic microorganism of the diarrhea in short time.In this work,we developed an electrochemical and colorimetric dual-mode detection for NoV based on the excellent dual catalytic properties of copper peroxide/COF-NH_(2)nanocomposite(CuO_(2)@COF-NH_(2)).For the colorimetric detection,NoV can be directly detected by the naked eye based on CuO_(2)@COF-NH_(2)as a laccase-like nonazyme using“peptide-NoV-antibody”recognition mode.The colorimetric assay displayed a wide and quality linear detection range from 1 copy/mL to 5000 copies/mL of NoV with a low limit of detection(LOD)of 0.125 copy/mL.For the electrochemical detection of NoV,CuO_(2)@COF-NH_(2)showed an oxidation peak of copper ion from Cu^(+)to Cu^(2+)using“peptide-NoV-antibody”recognition mode.The electrochemical assay showed a linear detection range was 1-5000 copies/mL with a LOD of 0.152 copy/mL.It's worthy to note that this assay does not need other electrical signal molecule,which provide the stable and sensitive electrochemial detection for NoV.The electrochemical and colorimetric dual-mode detection was used to detect NoV in foods and faceal samples,which has the potential for improving food safety and diagnosing of NoV-infected diarrhea.展开更多
Mercury ion(Hg^(2+)),a highly noxious of heavy metalion,has detrimental effects on the ecological environment and human health.Herein,we have developed an exonuclease III(Exo III)assisted catalytic hairpin assembly fo...Mercury ion(Hg^(2+)),a highly noxious of heavy metalion,has detrimental effects on the ecological environment and human health.Herein,we have developed an exonuclease III(Exo III)assisted catalytic hairpin assembly formation of a trivalent G-quadruplex/hemin DNAzyme for colorimetric detection of Hg^(2+).A hairpin DNA(Hr)was designed with thymine-Hg^(2+)-thymine pairs that catalyzed by Exo III is prompted to happen upon binding Hg^(2+).A released DNA fragment triggers the catalytic assembly of other three hairpins(H1,H2,and H3)to form many trivalent G-quadruplex/hemin DNA enzymes for signal output.The developed sensor shows a dynamic range from 2 pM to 2μM,with an impressively low detection limit of 0.32 pM for Hg^(2+)detection.Such a sensor also has good selectivity toward Hg^(2+)detection in the presence of other common metal ions.This strategy shows the great potential for visual detection with portable type.展开更多
The effects of the colorimetric buffer solutions were investigated while the two colorimetric reactions of A1 ferron complex and Fe ferron complex occurred individually, and the effects of the testing wavelength and t...The effects of the colorimetric buffer solutions were investigated while the two colorimetric reactions of A1 ferron complex and Fe ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexation colorimetric analysis method of A1 Fe ferron in view of the total concentration of ｛A1+Fe｝ was then established to determine the species distribution of polymeric Al Fe. The testing wavelength was recommended at 362 nm and the testing pH value was 5. With a comparison of the ratios of n Al / n Fe , the standard adsorption curves of the polymeric Al Fe solutions were derived from the experimental results. Furthermore, the solutions’composition were various in both the molar n Al / n Fe ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total [A1+Fe] which ranged from 10 -5 to 10 -4 mol/L.展开更多
A chemiluminescence enzyme immunoassay based on magnetic microparticles (MmPs-CLEIA) was developed to evaluate serum a-fetoprotein (AFP) in parallel with traditional colorimetric enzyme-linked immunosorbent assay (ELI...A chemiluminescence enzyme immunoassay based on magnetic microparticles (MmPs-CLEIA) was developed to evaluate serum a-fetoprotein (AFP) in parallel with traditional colorimetric enzyme-linked immunosorbent assay (ELISA).A systematic comparison between the MmPs-CLEIA and colorimetric ELISA concluded that the MPs-CLEIA exhibited fewer dosages of immunoreagents,less total assay time,and better linearity,recovery,precision,sensitivity and validity.AFP was detected in forty human serum samples by the proposed MPs-CLEIA and ELISA,and the results were compared with commercial electrochemiluminescence immunoassay (ECLIA) kit.The correlation coefficient between MPs-CLEIA and ELISA was obtained with R 2 0.6703;however,the correlation between MPs-CLEIA and ECLIA (R 2 0.9582) was obviously better than that between colorimetric ELISA and ECLIA (R 2 0.6866).展开更多
Metallic nanoparticles have received considerable attention in bioassays and diagnostics due to their unique surface plasmon resonance(SPR) properties.Gold nanoparticles have been employed for the development of SPR-b...Metallic nanoparticles have received considerable attention in bioassays and diagnostics due to their unique surface plasmon resonance(SPR) properties.Gold nanoparticles have been employed for the development of SPR-based colorimetric bioassays.In the present report we have described a sensitive colorimetric approach for estimation of proteins,within a detection limit of 10?80 μg/m L,using unmodified silver nanoparticles.Besides the common advantages of colorimetric assay such as simplicity,high sensitivity,and low cost,our method has a label-free design and provides an important and attractive alternative to classical sensing probes and systems.The present work will contribute to the development of nanotechnology-based diagnostic tools.展开更多
Okadaic acid(OA)is a typical marine toxin with strong toxicity causing diarrheic shellfish poisoning(DSP).Aptamers show great advantages in toxin detection and attract increasing attentions in the field of food analys...Okadaic acid(OA)is a typical marine toxin with strong toxicity causing diarrheic shellfish poisoning(DSP).Aptamers show great advantages in toxin detection and attract increasing attentions in the field of food analysis.In this study,a label-free col-orimetric aptasensor was constructed for visual and rapid detection of OA in shellfish.To exploit the binding capability of the anti-OA aptamer,the inherent molecular recognition mechanism of aptamer and OA was studied,based on molecular docking,fluorescent assay,and biolayer interferometry.Consistent results showed that the stem-loop near the 3’terminal of the aptamer exhibit dominate binding capacity.Based on the revealed recognition information,the aptamer was thus rationally utilized and combined with AuNPs and cationic polymer polydiallyl dimethyl ammonium chloride(PDDA)for the development of the label-free colorimetric aptasensor,in which the 3’terminal was thoroughly exposed to OA.The aptasensor provided robust performance with a linear detection range of 100-1200 nmol L-1,a limit of detection of 41.30 nmol L-1,recovery rates of 91.6%-106.2%,as well as a high selectivity towards OA in shellfish samples.The whole detection process can be completed within 1 h.To our best knowledge,this is the first time that the anti-OA aptamer was thoroughly studied,and a label-free colorimetric aptasensor was rationally designed in this way.This study not only provides a rapid detection method for highly sensitive and specific detection of OA,but also serves as a reference for the design of efficient aptasensors in the future.展开更多
Regulating the catalytic activity of nanozymes is significant for their applications in various fields.Here,we demonstrate a new strategy to achieve reversible regulation of the nanozyme’s activity for sensing purpos...Regulating the catalytic activity of nanozymes is significant for their applications in various fields.Here,we demonstrate a new strategy to achieve reversible regulation of the nanozyme’s activity for sensing purpose.This strategy involves the use of zero-dimensional MoS;quantum dots(MQDs)as the building blocks of nanozymes which display very weak peroxidase(POD)-like activity.Interestingly,such POD-like activity of the MQDs largely enhances in the presence of Fe;while diminishes with the addition of captopril thereafter.Further investigations identify the mechanism of Fe;-mediated aggregation-induced enhancement of the POD-like activity and the inhibitory effect of captopril on the enhancement,which is highly dependent on their concentrations.Based on this finding,a colorimetric method for the detection of captopril is developed.This sensing approach exhibits the merits of simplicity,rapidness,reliability,and low cost,which has been successfully applied in quality control of captopril in pharmaceutical products.Moreover,the present sensing platform allows smartphone read-out,which has promising applications in point-of-care testing devices for clinical diagnosis and drug analysis.展开更多
An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature res...An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature responses of primary initiation FAE and secondary initiation FAE in real time. And the characteristics of their temperature history curves were compared and analyzed. The results show that the primary initiation FAE has higher explosion temperature and longer duration compared to the secondary initiation FAE.展开更多
In order to accurately and automatically measure the light emitting diode(LED) colorimetric parameters,the design of a measurement system by adopting a high-performance spectrometer and looking-up table method was pre...In order to accurately and automatically measure the light emitting diode(LED) colorimetric parameters,the design of a measurement system by adopting a high-performance spectrometer and looking-up table method was presented based on the LabVIEW.First,the data of the LED relative spectral power distribution(SPD) were read by the spectrometer to measure LED chromaticity coordinate,and the slopes table were formed by the LED chromaticity coordinate and the equal stimulus point.Then,the CIE1931 chromaticity diagram was divided into 4 different regions to ensure the slopes table that had the character of monotonic decreasing.Finally,the LED dominant wavelength and purity were automatically calculated using the LabVIEW programs.The data of LEDs' colorimetric parameters have demonstrated that the measurement method in this paper can achieve higher precision result.展开更多
Nanocrystalline cellulose is an amphiphilic, high surface area material that can be easily functionalized and is biocompatible and eco-friendly. It has been used singularly and in combination with other nanomaterials ...Nanocrystalline cellulose is an amphiphilic, high surface area material that can be easily functionalized and is biocompatible and eco-friendly. It has been used singularly and in combination with other nanomaterials to optimize biosensor design. The attachment of peptides and proteins to nanocrystalline cellulose and their proven retention of activity provide a route to bioactive conjugates useful in designs for point of care biosensors. Elastase is a biomarker for a number of inflammatory diseases including chronic wounds, and its rapid sensitive detection with a facile approach to sensing is of interest. An increased interest in the use of elastase sensors for point of care diagnosis is resulting in a variety of approaches to elsastase sensors utilizing different detection technologies. Here elastase substrate peptide-celluose conjugates synthesized as colorimetric and fluorescent sensors on cotton cellulose nanocrystals are compared. The structure of the sensor peptide-nanocellulose crystals when modeled with computational crystal structure parameters demonstrates the spatio-stoichiometric features of the nanocrystalline surface that allows ligand to active site protease interacttion. An understanding of the structure/function relations of enzyme and conjugate substrate of the peptides covalently attached to nancellulose has implications for enhancing the biomolecular transducer. The potential applications of both fluorescent and colorimetric detection to markers like elastase using peptide cotton cellulose nanocrystals as a transducer surface to model point of care biosensors for protease detection are discussed.展开更多
A colorimetric method for the direct determination of hydrogen peroxide in aqueous solution is described. H2O2 stoichiometrically converts 4-nitrophenyl boronic acid or 4-nitrophenyl boronic acid pinacol ester into 4-...A colorimetric method for the direct determination of hydrogen peroxide in aqueous solution is described. H2O2 stoichiometrically converts 4-nitrophenyl boronic acid or 4-nitrophenyl boronic acid pinacol ester into 4-nitrophenol, which can be quantified by measuring the absorption at 400 nm in neutral or basic media. The reactions proceed fast under basic conditions and complete in 2 minutes to at pH 11 and 80?C. The linear range for the colorimetric method extends beyond 1.0 to 40 μM H2O2, and the limit of detection is ~1.0 μM H2O2. This method offers a convenient and practical process for rapid determination of hydrogen peroxide in aqueous media. Compared to many other techniques in H2O2 detection, this process is a direct measurement of H2O2, and is relatively unaffected by the presence of various salts, metal ions and the chelator EDTA.展开更多
A simple sensitive and rapid colorimetric method has been developed, and herein described, for the qualitative and quantitative chemical assessment of the commercially available chitosan products. The described method...A simple sensitive and rapid colorimetric method has been developed, and herein described, for the qualitative and quantitative chemical assessment of the commercially available chitosan products. The described method relies on the reactivity of the basic amino function of chitosan with the acid dye bromocresol purple. The applied technique allows assessment of variability and selectivity changes in the quality of the marketed chitosan products.展开更多
Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limite...Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.展开更多
The work described herein examines a rapid mix-and-measure method called DETECHIP suitable for screening of steroids and metabolites. The addition of steroids and metabolites to reactive arrays of colorimetric sensors...The work described herein examines a rapid mix-and-measure method called DETECHIP suitable for screening of steroids and metabolites. The addition of steroids and metabolites to reactive arrays of colorimetric sensors generated characteristic color “fingerprints” that were used to identify the analyte. A color analysis tool was used to identify the analyte pool that now includes biologically relevant analytes. The mix-and-measure arrays allowed the detection of disease metabolites, orotic acid and argininosuccinic acid;and the steroids androsterone, 1,4-androstadiene, testosterone, stanozolol, and estrone. The steroid 1,4-androstadiene was also detected by this method while dissolved in synthetic urine. Some of the steroids, such as androstadiene, stanozolol, and androsterone were co-dissolved with (2-hydroxypropyl)-β-cyclodextrin in order to increase solubility in aqueous buffered solutions. The colorimetric arrays do not intend to eliminate ELISA or mass spectroscopy based screening, but to possibly provide an alternative analytical detection method for steroids and metabolites.展开更多
A simple inexpensive method of monitoring hydrolysis of an antibiotic penicillin G (pen G) and subsequent enzyme detection using gold nanoparticles is presented. Gold nanoparticles capped with Cetyl trimethyl ammonium...A simple inexpensive method of monitoring hydrolysis of an antibiotic penicillin G (pen G) and subsequent enzyme detection using gold nanoparticles is presented. Gold nanoparticles capped with Cetyl trimethyl ammonium bromide (CTAB) are synthesized using chemical route. The particles could be used for detection of Penicillin G acylase (PGA) enzyme by incorporating hydrolysis reaction with pen G. This hydrolysis reaction leads to a shift in the surface plasmon band of gold nanoparticles from 527 nm to 545 nm accompanied by a visual colorimetric change in the solution from red to blue. The process is attributed to aggregation of nanoparticles caused due to displacement of CTAB bilayer by byproducts of the hydrolysis reaction. It is proposed that the presence of 0.007 mg/ml of PGA can be detected by a color change of gold nanoparticles solution without requiring any complicated instrument or highly trained operator to conduct the test. The method could also identify the presence of different penicillins by showing different spectral shifts. Thus the work presented here would be useful not only for the detection of the pharmaceutically important drug Pen G, but also represents a general methodology for the detection of enzymes, eg PGA.展开更多
A simple, rapid and precise method has been developed for determination of lipase activity in microbial media. The method is based on using phenyl acetate as substrate for lipase and determination of liberated phenol ...A simple, rapid and precise method has been developed for determination of lipase activity in microbial media. The method is based on using phenyl acetate as substrate for lipase and determination of liberated phenol by Folin Ciocalteu reagent. Reaction mixture containing substrate 2.4 ml of phenyl acetate 165 μM in Tris HCl buffer, 0.1 M and pH 7, with 1% (v/v) Triton X-100) and 0.1 ml lipase is incubated at 40?C during 10 minutes and the absorbance was measured at 750 nm. Linearity was observed in the concentration range 0-0.8 g/L lipase.展开更多
In this report, we present a method for the detection of Pb2+ based on the different adsorption capacity on the surface of gold nanoparticles (AuNPs) between ssDNA (single-stranded DNA) and G-quartet. In the absence o...In this report, we present a method for the detection of Pb2+ based on the different adsorption capacity on the surface of gold nanoparticles (AuNPs) between ssDNA (single-stranded DNA) and G-quartet. In the absence of Pb2+, the DNA oligonucleotides probe, which is guanine-rich ssDNA, can be adsorbed on the surface of AuNPs protecting them from aggregation. After adding Pb2+, the DNA oligonucleotides probe can specifically form compact G-quartet, which can induce the aggregation of unmodified AuNPs, especially after adding NaCl aqueous solution. Consequently, the color turns from red to blue. Pb2+ can be detected by colorimetric response of AuNPs;its detection limit can reach 5 μM only observed by naked eyes. Most metal ions have no interferences, and the interference of Cu2+ can be effectively eliminated by adding cysteine. It provides a simple and effective colorimetric sensor for on-site and real time detection of Pb2+.展开更多
This paper proposes a method of utilizing a flower-like MnOx nanozyme to conduct a colorimetric detection of ascorbic acid.The nanozyme is obtained by a chain of reaction of K3[Fe(CN)6],MnSO4·H2O,polyvinyl pyrrol...This paper proposes a method of utilizing a flower-like MnOx nanozyme to conduct a colorimetric detection of ascorbic acid.The nanozyme is obtained by a chain of reaction of K3[Fe(CN)6],MnSO4·H2O,polyvinyl pyrrolidone(PVP),NH4F,ethanol,and water.During the experimental process,the flower-like nanozyme is added to the mixed solution,including phosphate buffer,H2O2,and 3,3’,5,5’-tetramethylbe nzidine(TMB).The optimum reaction condition as following:pH 3.0,30μL 500mM H2O2,25μL 92 mM TMB,and 30μL 0.1mM nanozyme.Under the optimum condition,the detection range is 2-26mM,and the linear detection range is 2-20mM.展开更多
Oxytetracycline (OTC) is a common antibacterial agent used for the control of animal diseases. OTC abuse can seriously affect human health. Herein, based on the Fe(III)-3,3’,5,5’-tetramethylbenzidine (Fe(III)-TMB) s...Oxytetracycline (OTC) is a common antibacterial agent used for the control of animal diseases. OTC abuse can seriously affect human health. Herein, based on the Fe(III)-3,3’,5,5’-tetramethylbenzidine (Fe(III)-TMB) system, a facile and rapid colorimetricassay for oxytetracycline (OTC) was successfully developed. The addition of OTC could remarkably enhance the Fe(III)-oxidized TMB reaction and the absorbance increase of Fe(III)-TMB solution is proportional to the added OTC. The linear range of proposed sensor for OTC was from 20 nM to 1000 nM with the detection limit of 7.97 nM. The high sensitivity for OTC detection was successfully achieved under optimal conditions. For real sample analysis, recoveries of 89.93% to 100.02% was obtained. This is the first report for detecting OTC based on the nonenzymatic colorimetric reaction using the intrinsic oxidized activity of OTC/Fe3+ complex. The present simple, low-cost and visualized sensor has great potential for OTC detection in food.展开更多
基金supported by the National Natural Science Foundation of China(31922072)the Natural Science Foundation of Shandong Province(ZR2020JQ15)the Taishan Scholar Project of Shandong Province(tsqn201812020)。
文摘Sensitive monitoring of the target products during the biosynthesis process is crucial,and facile analytical approaches are urgently needed.Herein,phosphatidylserine(PS)was chosen as the model target,a colorimetric aptasensor was developed for the rapid quantitation in biosynthesis samples.A chimeric aptamer was constructed with two homogeneous original PS aptamers.Specific recognition between the chimeric aptamer and PS results in the desorption of aptamer from the surface of the AuNPs nanozyme,and the peroxidase-like enzymatic activity of the AuNPs nanozyme was weakened in a relationship with the different concentrations.The developed aptasensor performed well when applied for analyzing PS in biosynthesis samples.The aptasensor offers good sensitivity and selectivity,under optimal conditions,achieving monitoring and quantitation of PS in the range of 2.5-80.0μmol/L,with a limit of detection at 536.2 nmol/L.Moreover,the aptasensor provides good accuracy,with comparison rates of 98.17%-106.40%,when compared with the HPLC-ELSD.This study provides a good reference for monitoring other biosynthesized products and promoting the development of aptamers and aptasensors in real-world applications.
基金financially supported by National Key Research and Development Program of China(2022YFC2601604)Major science and technology project of Yunnan Province(202202AE090085)+9 种基金the National Natural Science Foundation of China(3216059732160236)Science and technology talent and platform plan of YunnanKey Scientific and Technology Project of Yunnan(202203AC100010)Spring City Plan:the High-level Talent Promotion and Training Project of Kunming(2022SCP001)the second phase of“Double-First Class”program construction of Yunnan Universitygrants from State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan,Yunnan University(2021KF005)Key Scientific and Technology Project of Yunnan(202002AE320005)Program for Excellent Young Talents of Yunnan Universitythe Program for Donglu Scholars of Yunnan University。
文摘Norovirus(NoV)is regarded as one of the most common causes of foodborne diarrhea in the world.It is urgent to identify the pathogenic microorganism of the diarrhea in short time.In this work,we developed an electrochemical and colorimetric dual-mode detection for NoV based on the excellent dual catalytic properties of copper peroxide/COF-NH_(2)nanocomposite(CuO_(2)@COF-NH_(2)).For the colorimetric detection,NoV can be directly detected by the naked eye based on CuO_(2)@COF-NH_(2)as a laccase-like nonazyme using“peptide-NoV-antibody”recognition mode.The colorimetric assay displayed a wide and quality linear detection range from 1 copy/mL to 5000 copies/mL of NoV with a low limit of detection(LOD)of 0.125 copy/mL.For the electrochemical detection of NoV,CuO_(2)@COF-NH_(2)showed an oxidation peak of copper ion from Cu^(+)to Cu^(2+)using“peptide-NoV-antibody”recognition mode.The electrochemical assay showed a linear detection range was 1-5000 copies/mL with a LOD of 0.152 copy/mL.It's worthy to note that this assay does not need other electrical signal molecule,which provide the stable and sensitive electrochemial detection for NoV.The electrochemical and colorimetric dual-mode detection was used to detect NoV in foods and faceal samples,which has the potential for improving food safety and diagnosing of NoV-infected diarrhea.
基金Supported by The Science and Technology Project of General Administration of Quality Supervision,Inspection and Quarantine (2015IK126)The Science and Technology Project of Changsha City of Hunan Province of China (KQ1602124).
文摘Mercury ion(Hg^(2+)),a highly noxious of heavy metalion,has detrimental effects on the ecological environment and human health.Herein,we have developed an exonuclease III(Exo III)assisted catalytic hairpin assembly formation of a trivalent G-quadruplex/hemin DNAzyme for colorimetric detection of Hg^(2+).A hairpin DNA(Hr)was designed with thymine-Hg^(2+)-thymine pairs that catalyzed by Exo III is prompted to happen upon binding Hg^(2+).A released DNA fragment triggers the catalytic assembly of other three hairpins(H1,H2,and H3)to form many trivalent G-quadruplex/hemin DNA enzymes for signal output.The developed sensor shows a dynamic range from 2 pM to 2μM,with an impressively low detection limit of 0.32 pM for Hg^(2+)detection.Such a sensor also has good selectivity toward Hg^(2+)detection in the presence of other common metal ions.This strategy shows the great potential for visual detection with portable type.
基金TheNationalNaturalScienceFoundationofChina (No .2 96 770 0 4)
文摘The effects of the colorimetric buffer solutions were investigated while the two colorimetric reactions of A1 ferron complex and Fe ferron complex occurred individually, and the effects of the testing wavelength and the pH of the solutions were also investigated. A timed complexation colorimetric analysis method of A1 Fe ferron in view of the total concentration of ｛A1+Fe｝ was then established to determine the species distribution of polymeric Al Fe. The testing wavelength was recommended at 362 nm and the testing pH value was 5. With a comparison of the ratios of n Al / n Fe , the standard adsorption curves of the polymeric Al Fe solutions were derived from the experimental results. Furthermore, the solutions’composition were various in both the molar n Al / n Fe ratios, i.e. 0/0, 5/5, 9/1 and 0/10, and the concentrations associated with the total [A1+Fe] which ranged from 10 -5 to 10 -4 mol/L.
基金supported by the National Basic Research Program of China (973 Program,no. 2007CB714507)National Nature Science Foundation of China (no. 90813015)
文摘A chemiluminescence enzyme immunoassay based on magnetic microparticles (MmPs-CLEIA) was developed to evaluate serum a-fetoprotein (AFP) in parallel with traditional colorimetric enzyme-linked immunosorbent assay (ELISA).A systematic comparison between the MmPs-CLEIA and colorimetric ELISA concluded that the MPs-CLEIA exhibited fewer dosages of immunoreagents,less total assay time,and better linearity,recovery,precision,sensitivity and validity.AFP was detected in forty human serum samples by the proposed MPs-CLEIA and ELISA,and the results were compared with commercial electrochemiluminescence immunoassay (ECLIA) kit.The correlation coefficient between MPs-CLEIA and ELISA was obtained with R 2 0.6703;however,the correlation between MPs-CLEIA and ECLIA (R 2 0.9582) was obviously better than that between colorimetric ELISA and ECLIA (R 2 0.6866).
基金Grants received by D. Dash from the Department of Biotechnology (DBT),Government of India,and Indian Council of Medical Research (ICMR),and equipment supports from the DST Unit on Nanoscience and Technology (DST-UNANST),Banaras Hindu University,and Humboldt Foundation
文摘Metallic nanoparticles have received considerable attention in bioassays and diagnostics due to their unique surface plasmon resonance(SPR) properties.Gold nanoparticles have been employed for the development of SPR-based colorimetric bioassays.In the present report we have described a sensitive colorimetric approach for estimation of proteins,within a detection limit of 10?80 μg/m L,using unmodified silver nanoparticles.Besides the common advantages of colorimetric assay such as simplicity,high sensitivity,and low cost,our method has a label-free design and provides an important and attractive alternative to classical sensing probes and systems.The present work will contribute to the development of nanotechnology-based diagnostic tools.
基金funded by the National Natural Sci-ence Foundation of China(No.31801620).
文摘Okadaic acid(OA)is a typical marine toxin with strong toxicity causing diarrheic shellfish poisoning(DSP).Aptamers show great advantages in toxin detection and attract increasing attentions in the field of food analysis.In this study,a label-free col-orimetric aptasensor was constructed for visual and rapid detection of OA in shellfish.To exploit the binding capability of the anti-OA aptamer,the inherent molecular recognition mechanism of aptamer and OA was studied,based on molecular docking,fluorescent assay,and biolayer interferometry.Consistent results showed that the stem-loop near the 3’terminal of the aptamer exhibit dominate binding capacity.Based on the revealed recognition information,the aptamer was thus rationally utilized and combined with AuNPs and cationic polymer polydiallyl dimethyl ammonium chloride(PDDA)for the development of the label-free colorimetric aptasensor,in which the 3’terminal was thoroughly exposed to OA.The aptasensor provided robust performance with a linear detection range of 100-1200 nmol L-1,a limit of detection of 41.30 nmol L-1,recovery rates of 91.6%-106.2%,as well as a high selectivity towards OA in shellfish samples.The whole detection process can be completed within 1 h.To our best knowledge,this is the first time that the anti-OA aptamer was thoroughly studied,and a label-free colorimetric aptasensor was rationally designed in this way.This study not only provides a rapid detection method for highly sensitive and specific detection of OA,but also serves as a reference for the design of efficient aptasensors in the future.
基金supported by the National Natural Science Foundation of China (Grant Nos.: 21775014 and 81972020)Open Foundation Project of Engineering Research Center for Biotechnology of Active Substances, Ministry of Education (Grant No.: AS201905)+1 种基金sponsored by the Chongqing Talent Program (Top-notch Youth)the Chongqing High-level Personnel of Special Support Program (Top-notch Youth), respectively
文摘Regulating the catalytic activity of nanozymes is significant for their applications in various fields.Here,we demonstrate a new strategy to achieve reversible regulation of the nanozyme’s activity for sensing purpose.This strategy involves the use of zero-dimensional MoS;quantum dots(MQDs)as the building blocks of nanozymes which display very weak peroxidase(POD)-like activity.Interestingly,such POD-like activity of the MQDs largely enhances in the presence of Fe;while diminishes with the addition of captopril thereafter.Further investigations identify the mechanism of Fe;-mediated aggregation-induced enhancement of the POD-like activity and the inhibitory effect of captopril on the enhancement,which is highly dependent on their concentrations.Based on this finding,a colorimetric method for the detection of captopril is developed.This sensing approach exhibits the merits of simplicity,rapidness,reliability,and low cost,which has been successfully applied in quality control of captopril in pharmaceutical products.Moreover,the present sensing platform allows smartphone read-out,which has promising applications in point-of-care testing devices for clinical diagnosis and drug analysis.
基金Sponsored by the National Natural Science Foundation of China (10772032)
文摘An infrared colorimetric radiation thermometrical system was established based on the theory of optical radiation. The dynamic temperature history of fuel air explosive (FAE) was measured to obtain the temperature responses of primary initiation FAE and secondary initiation FAE in real time. And the characteristics of their temperature history curves were compared and analyzed. The results show that the primary initiation FAE has higher explosion temperature and longer duration compared to the secondary initiation FAE.
基金National Natural Science Foundation of China (No. 51105289)Doctoral Program Foundation of Self-determined and Innovative Research Funds of WUT,China (No. 2010-ZY-JD-034)
文摘In order to accurately and automatically measure the light emitting diode(LED) colorimetric parameters,the design of a measurement system by adopting a high-performance spectrometer and looking-up table method was presented based on the LabVIEW.First,the data of the LED relative spectral power distribution(SPD) were read by the spectrometer to measure LED chromaticity coordinate,and the slopes table were formed by the LED chromaticity coordinate and the equal stimulus point.Then,the CIE1931 chromaticity diagram was divided into 4 different regions to ensure the slopes table that had the character of monotonic decreasing.Finally,the LED dominant wavelength and purity were automatically calculated using the LabVIEW programs.The data of LEDs' colorimetric parameters have demonstrated that the measurement method in this paper can achieve higher precision result.
文摘Nanocrystalline cellulose is an amphiphilic, high surface area material that can be easily functionalized and is biocompatible and eco-friendly. It has been used singularly and in combination with other nanomaterials to optimize biosensor design. The attachment of peptides and proteins to nanocrystalline cellulose and their proven retention of activity provide a route to bioactive conjugates useful in designs for point of care biosensors. Elastase is a biomarker for a number of inflammatory diseases including chronic wounds, and its rapid sensitive detection with a facile approach to sensing is of interest. An increased interest in the use of elastase sensors for point of care diagnosis is resulting in a variety of approaches to elsastase sensors utilizing different detection technologies. Here elastase substrate peptide-celluose conjugates synthesized as colorimetric and fluorescent sensors on cotton cellulose nanocrystals are compared. The structure of the sensor peptide-nanocellulose crystals when modeled with computational crystal structure parameters demonstrates the spatio-stoichiometric features of the nanocrystalline surface that allows ligand to active site protease interacttion. An understanding of the structure/function relations of enzyme and conjugate substrate of the peptides covalently attached to nancellulose has implications for enhancing the biomolecular transducer. The potential applications of both fluorescent and colorimetric detection to markers like elastase using peptide cotton cellulose nanocrystals as a transducer surface to model point of care biosensors for protease detection are discussed.
文摘A colorimetric method for the direct determination of hydrogen peroxide in aqueous solution is described. H2O2 stoichiometrically converts 4-nitrophenyl boronic acid or 4-nitrophenyl boronic acid pinacol ester into 4-nitrophenol, which can be quantified by measuring the absorption at 400 nm in neutral or basic media. The reactions proceed fast under basic conditions and complete in 2 minutes to at pH 11 and 80?C. The linear range for the colorimetric method extends beyond 1.0 to 40 μM H2O2, and the limit of detection is ~1.0 μM H2O2. This method offers a convenient and practical process for rapid determination of hydrogen peroxide in aqueous media. Compared to many other techniques in H2O2 detection, this process is a direct measurement of H2O2, and is relatively unaffected by the presence of various salts, metal ions and the chelator EDTA.
文摘A simple sensitive and rapid colorimetric method has been developed, and herein described, for the qualitative and quantitative chemical assessment of the commercially available chitosan products. The described method relies on the reactivity of the basic amino function of chitosan with the acid dye bromocresol purple. The applied technique allows assessment of variability and selectivity changes in the quality of the marketed chitosan products.
基金funded by the National Natural Science Foundation of China(No.31801620).
文摘Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.
文摘The work described herein examines a rapid mix-and-measure method called DETECHIP suitable for screening of steroids and metabolites. The addition of steroids and metabolites to reactive arrays of colorimetric sensors generated characteristic color “fingerprints” that were used to identify the analyte. A color analysis tool was used to identify the analyte pool that now includes biologically relevant analytes. The mix-and-measure arrays allowed the detection of disease metabolites, orotic acid and argininosuccinic acid;and the steroids androsterone, 1,4-androstadiene, testosterone, stanozolol, and estrone. The steroid 1,4-androstadiene was also detected by this method while dissolved in synthetic urine. Some of the steroids, such as androstadiene, stanozolol, and androsterone were co-dissolved with (2-hydroxypropyl)-β-cyclodextrin in order to increase solubility in aqueous buffered solutions. The colorimetric arrays do not intend to eliminate ELISA or mass spectroscopy based screening, but to possibly provide an alternative analytical detection method for steroids and metabolites.
文摘A simple inexpensive method of monitoring hydrolysis of an antibiotic penicillin G (pen G) and subsequent enzyme detection using gold nanoparticles is presented. Gold nanoparticles capped with Cetyl trimethyl ammonium bromide (CTAB) are synthesized using chemical route. The particles could be used for detection of Penicillin G acylase (PGA) enzyme by incorporating hydrolysis reaction with pen G. This hydrolysis reaction leads to a shift in the surface plasmon band of gold nanoparticles from 527 nm to 545 nm accompanied by a visual colorimetric change in the solution from red to blue. The process is attributed to aggregation of nanoparticles caused due to displacement of CTAB bilayer by byproducts of the hydrolysis reaction. It is proposed that the presence of 0.007 mg/ml of PGA can be detected by a color change of gold nanoparticles solution without requiring any complicated instrument or highly trained operator to conduct the test. The method could also identify the presence of different penicillins by showing different spectral shifts. Thus the work presented here would be useful not only for the detection of the pharmaceutically important drug Pen G, but also represents a general methodology for the detection of enzymes, eg PGA.
文摘A simple, rapid and precise method has been developed for determination of lipase activity in microbial media. The method is based on using phenyl acetate as substrate for lipase and determination of liberated phenol by Folin Ciocalteu reagent. Reaction mixture containing substrate 2.4 ml of phenyl acetate 165 μM in Tris HCl buffer, 0.1 M and pH 7, with 1% (v/v) Triton X-100) and 0.1 ml lipase is incubated at 40?C during 10 minutes and the absorbance was measured at 750 nm. Linearity was observed in the concentration range 0-0.8 g/L lipase.
文摘In this report, we present a method for the detection of Pb2+ based on the different adsorption capacity on the surface of gold nanoparticles (AuNPs) between ssDNA (single-stranded DNA) and G-quartet. In the absence of Pb2+, the DNA oligonucleotides probe, which is guanine-rich ssDNA, can be adsorbed on the surface of AuNPs protecting them from aggregation. After adding Pb2+, the DNA oligonucleotides probe can specifically form compact G-quartet, which can induce the aggregation of unmodified AuNPs, especially after adding NaCl aqueous solution. Consequently, the color turns from red to blue. Pb2+ can be detected by colorimetric response of AuNPs;its detection limit can reach 5 μM only observed by naked eyes. Most metal ions have no interferences, and the interference of Cu2+ can be effectively eliminated by adding cysteine. It provides a simple and effective colorimetric sensor for on-site and real time detection of Pb2+.
文摘This paper proposes a method of utilizing a flower-like MnOx nanozyme to conduct a colorimetric detection of ascorbic acid.The nanozyme is obtained by a chain of reaction of K3[Fe(CN)6],MnSO4·H2O,polyvinyl pyrrolidone(PVP),NH4F,ethanol,and water.During the experimental process,the flower-like nanozyme is added to the mixed solution,including phosphate buffer,H2O2,and 3,3’,5,5’-tetramethylbe nzidine(TMB).The optimum reaction condition as following:pH 3.0,30μL 500mM H2O2,25μL 92 mM TMB,and 30μL 0.1mM nanozyme.Under the optimum condition,the detection range is 2-26mM,and the linear detection range is 2-20mM.
文摘Oxytetracycline (OTC) is a common antibacterial agent used for the control of animal diseases. OTC abuse can seriously affect human health. Herein, based on the Fe(III)-3,3’,5,5’-tetramethylbenzidine (Fe(III)-TMB) system, a facile and rapid colorimetricassay for oxytetracycline (OTC) was successfully developed. The addition of OTC could remarkably enhance the Fe(III)-oxidized TMB reaction and the absorbance increase of Fe(III)-TMB solution is proportional to the added OTC. The linear range of proposed sensor for OTC was from 20 nM to 1000 nM with the detection limit of 7.97 nM. The high sensitivity for OTC detection was successfully achieved under optimal conditions. For real sample analysis, recoveries of 89.93% to 100.02% was obtained. This is the first report for detecting OTC based on the nonenzymatic colorimetric reaction using the intrinsic oxidized activity of OTC/Fe3+ complex. The present simple, low-cost and visualized sensor has great potential for OTC detection in food.
