Facile synthesis of pH‐responsive glycopolypeptides with adjustable sugar density

Well‐defined pH‐responsive glycopolypeptides were prepared by polymer‐analogous aqueous amide coupling of d ‐glucosamine to poly(α,l ‐glutamic acid) (PGA) using the coupling agent 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium chloride (DMT‐MM) without any organic solvents, additives, or buffers. Degrees of substitution (DS) up to 80% can be achieved, and the DS is adjustable by the molar ratio of DMT‐MM to PGA repeating units. Successful glycosylation of both low MW and high MW PGA was confirmed by ¹H NMR and FTIR spectroscopy as well as by an enhanced solubility at low pH. CD spectroscopy revealed that glycosylated PGAs with a DS up to 0.63 are able to undergo a pH‐responsive and reversible helix‐coil transition. However, for polymers with higher DS no transition occurs. A comparison with PGAs functionalized with monoethanolamine showed that the low helicity at high DS is not a steric effect due to the bulky sugar moieties, but a solvation effect. Preliminary turbidimetric tests with the lectin Concanavalin A indicate a biological activity of these glycosylated polypeptides. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3925–3931     

Bioinspired polymer functionalized with a diiron carbonyl model complex and its assembly onto the surface of a gold electrode via “click” chemistry

A complex pendant with two ethynyl groups, [Fe₂(μ‐SCH₂CCH)₂(CO)₆] ( 2 ), as a model of the diiron subunit of [FeFe]‐hydrogenase was polymerized and the {Fe₂(CO)₆} core was successfully incorporated into the polymer matrix. The polymer was characterized by a variety of spectroscopic techniques, TGA, FTIR, SEM, TEM, and NMR. The resultant polymer was immobilized via “click” chemistry using its terminal C?CH bond onto the surface of a gold electrode, which was premodified with azidothiol by self‐assembled monolayer (SAM). The assembled electrode showed electrochemical responses. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2410–2417, 2010     

Synthesis,self‐assembly and recognition properties of biomimetic star‐shaped poly(ε‐caprolactone)‐b‐glycopolymer block copolymers

Biomimetic star‐shaped poly(ε‐caprolactone)‐b‐poly(gluconamidoethyl methacrylate) block copolymers (SPCL‐PGAMA) were synthesized from the atom transfer radical polymerization (ATRP) of unprotected GAMA glycomonomer using a tetra(2‐bromo‐2‐methylpropionyl)‐terminated star‐shaped poly(ε‐caprolactone) (SPCL‐Br) as a macroinitiator in NMP solution at room temperature. The block length of PGAMA glycopolymer within as‐synthesized SPCL‐PGAMA copolymers could be adjusted linearly by controlling the molar ratio of GAMA glycomonomer to SPCL‐Br macroinitiator, and the molecular weight distribution was reasonably narrow. The degree of crystallization of PCL block within copolymers decreased with the increasing block length ratio of outer PGAMA to inner PCL. Moreover, the self‐assembly properties of the SPCL‐PGAMA copolymers were investigated by NMR, UV‐vis, DLS, and TEM, respectively. The self‐assembled glucose‐installed aggregates changed from spherical micelles to worm‐like aggregates, then to vesicles with the decreasing weight fraction of hydrophilic PGAMA block. Furthermore, the biomolecular binding of SPCL‐PGAMA with Concanavalin A (Con A) was studied by means of UV‐vis, fluorescence spectroscopy, and DLS, which demonstrated that these SPCL‐PGAMA copolymers had specific recognition with Con A. Consequently, this will not only provide biomimetic star‐shaped SPCL‐PGAMA block copolymers for targeted drug delivery, but also improve the compatibility and drug release properties of PCL‐based biomaterials for hydrophilic peptide drugs. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 817–829, 2008     

Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase: A chemistry–biology interdisciplinary study of the protein's structure–function–reaction mechanism relationships

The oxidosqualene cyclases (EC 5.4.99‐) constitute a family of enzymes that catalyze diverse cyclization/rearrangement reactions of (3S)‐2,3‐oxidosqualene into a distinct array of sterols and triterpenes. The relationship between the cyclization mechanism and the enzymatic structure is extremely complex and compelling. This review covers the historical achievements of biomimetic studies and current progress in structural biology, molecular genetics, and bioinformatics studies to elucidate the mechanistic and structure–function relationships of the Saccharomyces cerevisiae oxidosqualene‐lanosterol cyclase‐catalyzed cyclization/rearrangement reaction. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 302–325; 2008: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20157     

Biomimetic superhydrophobic UHMWPE/nanosilica films with different sticky behavior on several metals

A kind of organic–inorganic composite film with biomimetic superhydrophobic performance was prepared on several metals including steel, aluminum, and copper. The organic matrix was ultrahigh‐molecular‐weight polyethylene (UHMWPE), and the inorganic filler was nanosilica. Scanning electron microscope observation indicated addition of nanosilica greatly changed the topography of the UHMWPE film. Special convexities were formed on the surfaces of the composite films, which made the composite films rougher than that of pure UHMWPE film. The nanosilica randomly scattered on the surface of the convexities and formed hierarchical structure similar to that of some plant leaves with superhydrophobic characteristics. Interestingly, it was found that there were remarkable differences between the sliding angles (SA) of water droplet on the composite films on different metals although the contact angles (CA) of water droplet on these films were quite close. The CA on the composite films on steel was about 157°, and the SA was larger than 90°, which demonstrated obvious superhydrophobic and sticky characteristic. But to the films on aluminum and copper, the CAs on them were larger than 160° and the SAs were between 3° and 4°, which meant excellent superhydrophobic and roll‐off performance. Scanning electron microscope observation indicated that there were some micro‐orifices in the film on steel and these micro‐orifices were connected to some extent. It was believed that these micro‐orifices provided capillary force and restrained sliding of water droplet. A sticky model based on capillary mechanism was proposed. Copyright © 2017 John Wiley & Sons, Ltd.     

仿海豚皮减阻研究进展

减阻材料可广泛应用于国防、工业、生产生活,具有极大的应用价值。而仿生减阻作为减阻研究新的分枝,受到广泛关注。由Gray计算海豚游动阻力与肌肉力量不匹配而产生的“Gray悖论”开启了对海豚减阻机理的探索。本文介绍了基于海豚表皮的几种减阻机理,并介绍由其发展出的相应减阻材料的设计与测试,最后对仿海豚皮减阻研究的未来发展进行展望。