Peptide‐functionalized reduced graphene oxide as a bioactive mechanically robust tissue regeneration scaffold

Bioactive, synthetic materials represent next‐generation composites for tissue regeneration. Design of contemporary materials attempts to recapitulate the complexities of native tissue; however, few successfully mimic the order in nature. Recently, graphene oxide (GO ) has emerged as a scaffold due to its potential for bioactive functionalization and long‐range order instilled by the self‐assembly of graphene sheets. Chemical reduction of GO results in a more compatible material with enhanced properties but compromises the ability to functionalize the graphenic backbone. However, using Johnson–Claisen rearrangement chemistry, functionalization is achieved that is not liable to reduction. From reduced Claisen graphene, we polymerized short homopeptides from α ‐amino acid N ‐carboxyanhydride monomers of glutamate and lysine to result in functionalized graphenes (pGlu‐rCG and pLys‐rCG ) that are cytocompatible, degradable, and bioactive. Exposure to NIH‐3T3 fibroblasts and RAW 264.7 macrophages revealed that the materials are cytocompatible and do not alter important sub‐cellular compartments. Powders were hot pressed to form mechanically stiff (E ′: 41 and 49 MPa ), strong (UCS : 480 and 140 MPa ), and tough (U _T: 2898 and 584 J m^?3 × 10⁴) three‐dimensional constructs (pGlu‐rCG and pLys‐rCG, respectively). Overall, we report a robust chemistry and processing strategy for facile bioactive functionalization of compatible, reduced Claisen graphene for three‐dimensional biomedical applications. © 2017 Society of Chemical Industry     

Low-temperature plasma modified Vulcan XC72R as a support to enhance the methanol oxidation performance of Pt nanoparticles

Vulcan XC72R as a kind of carbon material is widely used as a support to deposit metal catalysts. However, its low pore size, the difficulty of dispersion, and the rare sites have limited its application. In this work, we modified the surface of Vulcan XC72R by low-temperature plasma. It is detected that its original morphology and structure have been greatly changed by longtime plasma irradiation. The pore size increased and the specific surface area decreased with the increasing treatment time, while the pore volume initially increased and then decreased. Meanwhile, the outside surfaces of Vulcan XC72R were exfoliated to ultra-thin nanosheets and grafted with the oxygen-containing functional groups. Compared with the untreated Vulcan XC72R, Pt nanoparticles supported on treated Vulcan XC72R with smaller size exhibited higher catalyst activity and longer cyclic stability for the methanol oxidation reaction. This study demonstrates that plasma is an efficient approach to tuning the pore size and functionalizing the surface of Vulcan XC72R.     

Directed Evolution of a Cp*RhIII-Linked Biohybrid Catalyst Based on a Screening Platform with Affinity Purification

Directed evolution of Cp*Rh^III-linked nitrobindin (NB), a biohybrid catalyst, was performed based on an in vitro screening approach. A key aspect of this effort was the establishment of a high-throughput screening (HTS) platform that involves an affinity purification step employing a starch-agarose resin for a maltose binding protein (MBP) tag. The HTS platform enables efficient preparation of the purified MBP-tagged biohybrid catalysts in a 96-well format and eliminates background influence of the host E. coli cells. Three rounds of directed evolution and screening of more than 4000 clones yielded a Cp*Rh^III-linked NB(T98H/L100K/K127E) variant with a 4.9-fold enhanced activity for the cycloaddition of acetophenone oximes with alkynes. It is confirmed that this HTS platform for directed evolution provides an efficient strategy for generating highly active biohybrid catalysts incorporating a synthetic metal cofactor.     

Rheological and thermal properties of epoxy nanocomposites reinforced with alkylated multi‐walled carbon nanotubes

The effects of functionalized multi‐walled carbon nanotubes (MWCNTs) on thermal and chemorheological behaviors of an epoxy‐based nanocomposite system were investigated. Chemical functionalization of MWCNTs by acid modification (A‐MWCNTs) and chemical amidation (D‐MWCNTs) was confirmed using Fourier transform infrared spectroscopy and thermogravimetric analysis. It was found that the D‐MWCNTs had a significant effect on the chemorheological behaviors of the epoxy‐based nanocomposite. Compared to the epoxy/A‐MWCNT nanocomposite, the epoxy/D‐MWCNTs nanocomposite showed a significant increase in gel time, as obtained from isothermal rheology measurements. Also, the storage modulus of the diglycidylether of bisphenol F (DGEBF)/D‐MWCNTs nanocomposite was higher than that of the DGEBF/D‐MWCNTs nanocomposite and gradually increased with an increase of frequency. This could be interpreted by the relatively strongly interconnected structure of the D‐MWCNTs in the DGEBF epoxy resin, which arises from the functionalized alkyl groups of the D‐MWCNTs in dispersion phases with the DGEBF epoxy resin. Copyright © 2012 Society of Chemical Industry     

Some recent advances in polyolefin functionalization

Polyolefin‐based materials are increasingly being used in many industrial applications for packaging, automotive and construction materials. The recent developments of research have been aimed at making these materials, often complex, being mixtures, block copolymers, micro‐ and nanocomposites with inorganic and organic fillers, more efficient and environmentally friendly (through recycling processes, and the use of bio‐polyolefins). In this context, functionalized polyolefins, on the one hand, play a fundamental role in improving the morphology and thus the thermal and mechanical properties of heterophase systems, and, on the other hand, provide new materials difficult to obtain by conventional synthesis in connection with the type of inserted functionality. Therefore it appears to be of interest to report and discuss here the recent results concerning the radical grafting in the melt of different functionalities onto polyolefins as well as the capability reached of modulating ad hoc the degree of grafting and the final structure/architecture of functionalized polyolefins. © 2013 Society of Chemical Industry     

Poly(vinyl alcohol) functionalization with aldehydes in organic solvents: Shining properties of poly(vinyl acetals)

Poly(vinyl alcohol) has been functionalized with aldehydes in tetrahydrofuran (THF) with a good control of the grafting. A wide library of poly(vinyl acetals) could be obtained in order to study some structure/property correlations. The influence of the aldehyde nature on the functionalization rates has been studied, in particular for optical properties by measurement of the shininess for further applications in the cosmetic field. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40677.     

功能化磁性Fe_3O_4纳米材料去除水污染物研究进展

磁性纳米材料具有较强的化学稳定性、较高的生物相容性和良好的吸附性能,在外加磁场的作用下可迅速分离,同时还能通过表面修饰或改性等方法使其功能化,因此在去除水环境污染物方面有着广泛的应用前景。通过总结近年来的相关研究资料,综述了不同方法修饰的Fe_3O_4功能化磁性纳米材料在去除水污染物方面的研究进展,指出了当前研究中的主要发展方向和有待解决的问题。