p21^wafl/cipl, best known as a broad-specificity inhibitor of cyclin/cyclin-dependent kinase complexes, can interact with various target proteins, and this ability relies on its structural plasticity. Therefore, studi...p21^wafl/cipl, best known as a broad-specificity inhibitor of cyclin/cyclin-dependent kinase complexes, can interact with various target proteins, and this ability relies on its structural plasticity. Therefore, studies on the structural properties of p21 are very important to understand its structure-function relationship. However, detailed studies on its secondary structure and biophysical propertics have been comparatively sparse. A human p21 gene was cloned into the temperature expression vector pBV220 and transformed into Escherichia coli strain JM109. Recombinant protein was expressed as a non-fusion protein and purified by gel filtration and anion exchange chromatography. The purified protein was verified by Western blot and the functional activity was recognized by pull-down assay. Furthermore, circular dichroism, fluorescence spectroscopy, and fluorescence quenching methods were used to characterize the conformational properties of the purified protein. The results indicate that it was largely unstructured under the native solution conditions, and its tryptophan residues were exposed and located in a positively charged microenvironment. This study lays a good foundation for further study of p21 binding to its different partners.展开更多
The effects of oligodeoxynucleotide （ODN） on the conformation of basic fibroblast growth factor （bFGF） were studied by spectral method. The results showed that ODN destabilized the protein.
Semiconductor nanomaterials with photocatalytic activity have potential for many applications. An effective way of promoting photocatalytic activity is depositing noble metal nanoparticles （NPs） on a semiconductor, ...Semiconductor nanomaterials with photocatalytic activity have potential for many applications. An effective way of promoting photocatalytic activity is depositing noble metal nanoparticles （NPs） on a semiconductor, since the noble metal NPs act as excellent electron acceptors which inhibit the quick recombination of the photoexcited electron-hole pairs and thereby enhance the generation of reactive oxygen species （ROS）. Herein, a highly effective platform, graphitic carbon nitride （g-C3N4） nanosheets with embedded Ag nanopartides （Ag/g-C3N4）, was synthesized by a facile route. Under visible light irradiation, the ROS production of Ag/g-C3N4 nanohybrids was greatly improved compared with pristine g-C3N4 nanosheets, and moreover, the nanohybrids showed enhanced antibacterial efficacy and ability to disperse bacterial biofilms. We demonstrate for the first time that the Ag/g-C3N4 nanohybrids are efficient bactericidal agents under visible light irradiation, and can also provide a new way for biofilm elimination. The enhanced antibacterial properties and biofilm-disrupting ability of Ag/g-C3N4 nanohybrids may offer many biomedical applications.展开更多
A non-destructive, safe and practical strategy to produce high quality graphene in high yield is urgently required, since this would pave the way for a wide range of applications of graphene in the future. Here we pre...A non-destructive, safe and practical strategy to produce high quality graphene in high yield is urgently required, since this would pave the way for a wide range of applications of graphene in the future. Here we present a pH-responsive water-dispersible method for the exfoliation and functionalization of graphene by using lysozyme. The pH-responsive dispersion of graphene may be useful for the reversible assembly of multicomponent/multifunctional nanohybrid materials and nanoscale electronic devices. More importantly, composites can be easily constructed through the interactions between disulphide groups in lysozyme and gold nanoparticles （AuNPs）. The resulting graphene-AuNPs composites show excellent catalytic activity towards reduction of o-nitroaniline by NaBH4. Since lysozyme is low cost and has antibacterial properties, and has been widely used in food preservation, medicine and the pharmaceutical industry, our approach may open a new scalable route for the manufacture of high-quality, nondestructive graphene for practical applications.展开更多
Luminescent carbon nanoparticles （CNPs） are newcomers to the world of nanomaterials and have shown great impact in health and environmental applications as well as being promising building blocks for future nanodevi...Luminescent carbon nanoparticles （CNPs） are newcomers to the world of nanomaterials and have shown great impact in health and environmental applications as well as being promising building blocks for future nanodevices because of their fascinating photoluminescence and potential to serve as nontoxic replacements for traditional heavy-metals-based quantum dots. Herein, fluorescent CNPs have been prepared from candle soot by re fluxing with HNO3 and subsequently separated by a single centrifugation. The CNPs can be represented by the empirical formula C1Ho.677Oo.586No.o15Nao.069, and have a size of 20-100 nm, height of 3.0 nm, lifetime of 7.31 ns ＋ 0.06 ns and quantum yield of -1.7%. Further studies demonstrate that： （1）the as-prepared CNPs exhibit excellent stability in biological media and their luminescence intensity does not change with ionic strength or pH in the physiological and pathological range of pH 4.5-8.8; （2） CNPs can act as electron donors and transporters and porphyrin can assemble onto CNPs through electrostatic and ^-stacking interactions to form porphyrin-CNPs supramolecular composites; （3）CNPs have strong intrinsic peroxidase-like activity. Based on this intrinsic peroxidase activity, a simple, cheap, and highly selective and sensitive colorimetric and quantitative assay has been developed for the detection of glucose levels. This assay has been used to analyze real samples, such as diluted blood and fruit juice.展开更多
基金Supported by the National Natural Science Foundation of China(Nos20225102, 20331020, 20325101 and 20473084)Hundred People Program of Chinese Academy of Sciences
文摘p21^wafl/cipl, best known as a broad-specificity inhibitor of cyclin/cyclin-dependent kinase complexes, can interact with various target proteins, and this ability relies on its structural plasticity. Therefore, studies on the structural properties of p21 are very important to understand its structure-function relationship. However, detailed studies on its secondary structure and biophysical propertics have been comparatively sparse. A human p21 gene was cloned into the temperature expression vector pBV220 and transformed into Escherichia coli strain JM109. Recombinant protein was expressed as a non-fusion protein and purified by gel filtration and anion exchange chromatography. The purified protein was verified by Western blot and the functional activity was recognized by pull-down assay. Furthermore, circular dichroism, fluorescence spectroscopy, and fluorescence quenching methods were used to characterize the conformational properties of the purified protein. The results indicate that it was largely unstructured under the native solution conditions, and its tryptophan residues were exposed and located in a positively charged microenvironment. This study lays a good foundation for further study of p21 binding to its different partners.
文摘The effects of oligodeoxynucleotide （ODN） on the conformation of basic fibroblast growth factor （bFGF） were studied by spectral method. The results showed that ODN destabilized the protein.
基金This work was supported by the National Basic Research Program of China （Nos. 2011CB936004 and 2012CB720602） and the National Natural Science Foundation of China （Nos. 21210002, 21431007, 91413111, 21402183）.
文摘Semiconductor nanomaterials with photocatalytic activity have potential for many applications. An effective way of promoting photocatalytic activity is depositing noble metal nanoparticles （NPs） on a semiconductor, since the noble metal NPs act as excellent electron acceptors which inhibit the quick recombination of the photoexcited electron-hole pairs and thereby enhance the generation of reactive oxygen species （ROS）. Herein, a highly effective platform, graphitic carbon nitride （g-C3N4） nanosheets with embedded Ag nanopartides （Ag/g-C3N4）, was synthesized by a facile route. Under visible light irradiation, the ROS production of Ag/g-C3N4 nanohybrids was greatly improved compared with pristine g-C3N4 nanosheets, and moreover, the nanohybrids showed enhanced antibacterial efficacy and ability to disperse bacterial biofilms. We demonstrate for the first time that the Ag/g-C3N4 nanohybrids are efficient bactericidal agents under visible light irradiation, and can also provide a new way for biofilm elimination. The enhanced antibacterial properties and biofilm-disrupting ability of Ag/g-C3N4 nanohybrids may offer many biomedical applications.
基金Acknowledgements Financial support was provided by the National Basic Research Program （973 Program） of China （Nos. 2011CB936004 and 2012CB720602）, and theNational Natural Science Foundation of China （NSFC）, Nos. （21210002 and 91213302）.
文摘A non-destructive, safe and practical strategy to produce high quality graphene in high yield is urgently required, since this would pave the way for a wide range of applications of graphene in the future. Here we present a pH-responsive water-dispersible method for the exfoliation and functionalization of graphene by using lysozyme. The pH-responsive dispersion of graphene may be useful for the reversible assembly of multicomponent/multifunctional nanohybrid materials and nanoscale electronic devices. More importantly, composites can be easily constructed through the interactions between disulphide groups in lysozyme and gold nanoparticles （AuNPs）. The resulting graphene-AuNPs composites show excellent catalytic activity towards reduction of o-nitroaniline by NaBH4. Since lysozyme is low cost and has antibacterial properties, and has been widely used in food preservation, medicine and the pharmaceutical industry, our approach may open a new scalable route for the manufacture of high-quality, nondestructive graphene for practical applications.
基金This project was supported by the 973 Project （No. 2011CB936004）, the National Natural Science Foundation of China （NSFC） （Nos. 20831003, 90813001, 20833006, and 90913007） and Funds from the Chinese Academy of Sciences.
文摘Luminescent carbon nanoparticles （CNPs） are newcomers to the world of nanomaterials and have shown great impact in health and environmental applications as well as being promising building blocks for future nanodevices because of their fascinating photoluminescence and potential to serve as nontoxic replacements for traditional heavy-metals-based quantum dots. Herein, fluorescent CNPs have been prepared from candle soot by re fluxing with HNO3 and subsequently separated by a single centrifugation. The CNPs can be represented by the empirical formula C1Ho.677Oo.586No.o15Nao.069, and have a size of 20-100 nm, height of 3.0 nm, lifetime of 7.31 ns ＋ 0.06 ns and quantum yield of -1.7%. Further studies demonstrate that： （1）the as-prepared CNPs exhibit excellent stability in biological media and their luminescence intensity does not change with ionic strength or pH in the physiological and pathological range of pH 4.5-8.8; （2） CNPs can act as electron donors and transporters and porphyrin can assemble onto CNPs through electrostatic and ^-stacking interactions to form porphyrin-CNPs supramolecular composites; （3）CNPs have strong intrinsic peroxidase-like activity. Based on this intrinsic peroxidase activity, a simple, cheap, and highly selective and sensitive colorimetric and quantitative assay has been developed for the detection of glucose levels. This assay has been used to analyze real samples, such as diluted blood and fruit juice.
