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Free Amino Groups (free + amino_groups)

Distribution by Scientific Domains
Polymers and Materials Science66%

Selected Abstracts

Aliphatic poly(ester-carbonate)s bearing amino groups and its RGD peptide grafting

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2008
Xiuli Hu
Abstract This article deals with (1) synthesis of novel cyclic carbonate monomer (2-oxo [1,3]dioxan-5-yl)carbamic acid benzyl ester (CAB) containing protected amino groups; (2) ring-opening copolymerization of the cyclic monomer with L -lactide (LA) to provide novel degradable poly(ester-carbonate)s with functional groups; (3) removal of the protective benzyloxycarbonyl (Cbz) groups by catalytic hydrogenation to afford the corresponding poly(ester- co -carbonate)s with free amino groups; (4) grafting of oligopeptide Gly-Arg-Gly-Asp-Ser-Tyr (GRGDSY, abbreviated as RGD) onto the copolymer pendant amino groups in the presence of 1,1,-carbonyldiimidazole (CDI). The structures of P(LA- co -CA/RGD) and its precursor were confirmed by 1H NMR analysis. Cell experiments showed that P(LA- co -CA/RGD) had improved adhesion and proliferation behavior. Therefore, the novel RGD-grafted block copolymer is promising for cell or tissue engineering applications. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7022,7032, 2008 [source]

Preparation of a Novel Polymer-Modified Si Surface for DNA Immobilization

MACROMOLECULAR BIOSCIENCE, Issue 5 2009
Gökçen Birlik Demirel
Abstract The design of a novel polymer-modified overlayer composed of PPAPE and GPMS on a silicon wafer for immobilization of DNA molecules is described. After hydroxylation of Si(100) surfaces, GPMS molecules were self-assembled onto these surfaces. PPAPE molecules were then covalently attached to the epoxy-terminated surfaces. The incubation time and concentration of PPAPE was found to effect both layer thickness and water CA. The type of organic solvent and the pH were found to change the nature of the PPAPE-modified surface for DNA immobilization. It is concluded that PPAPE-modified surfaces show advantages for DNA immobilization by electrostatic interactions between DNA molecules and positively charged free amino groups of the PPAPE-modified surfaces at the appropriate pH values. [source]

Regioselective Grafting of Poly(ethylene glycol) onto Chitosan and the Properties of the Resulting Copolymers

MACROMOLECULAR BIOSCIENCE, Issue 10 2006
Li Liu
Abstract Summary: PEG was grafted onto chitosan regioselectively at the hydroxyl groups with phthaloylchitosan as an intermediate. After the graft reaction, the phthaloyl groups were deprotected to give chitosan- g -PEG copolymers with free amino groups. The chemical structure of the graft copolymers was confirmed by FT-IR, 1H and 13C NMR spectroscopy. The resulting graft copolymers showed improved thermal stability compared to the original chitosan, and showed a lower thermal transition temperature at around 185,°C. Chitosan- g -PEG exhibited a high affinity not only for aqueous acid but also for some organic solvents because of the presence of abundant free amino groups and PEG branches, and it exhibited higher hygroscopicity and moisture retention ability than chitosan. [source]

Study of the near-neutral pH-sensitivity of chitosan/gelatin hydrogels by turbidimetry and microcantilever deflection

BIOTECHNOLOGY & BIOENGINEERING, Issue 3 2006
Jinshu Mao
Abstract The fundamental properties and pH-sensitivity of chitosan/gelating hydrogels were investigated using spectroscopic and microelectro mechanical (MEMS) measurement approaches. Turbidimetric titration revealed that there were electrostatic attractive interactions between tripolyphosphate (TPP), chitosan, and gelatin in the acidic pH range, depending on their degree of ionization. The pH-sensitive swelling behavior of the hydrogels was investigated by monitoring the deflection of hydrogel-coated microcantilevers, which exhibited a sensitive and repeatable response to solution pH. The deflection of the microcantilever increased as the pH decreased, and the response speed of the system exhibited a nearly linear relationship with pH. The effects of the pH and concentration of TPP solution, as well as the ratio of chitosan to gelatin in gel precursor solutions, on the pH sensitivity of the hydrogels were also investigated. It was found that the swelling of the hydrogel is mainly a result of chain relaxation of chitosan,TPP complexes caused by protonation of free amino groups in chitosan, which depends on the crosslinking density set during the formation of the network. An increase in initial crosslink density induced a decrease in swelling and pH sensitivity. It can be concluded from this study that pH-sensitive chitosan gel properties can be tuned by preparatory conditions and inclusion of gelatin. Furthermore, microcantilevers can be used as a platform for gaining increased understanding of environmentally sensitive polymers. © 2006 Wiley Periodicals, Inc. [source]

Multienzyme catalysis in microfluidic biochips

BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003
Moo-Yeal Lee
Abstract The attachment of enzymes to glass microfluidic channels has been achieved using a highly reactive poly(maleic anhydride- alt -,-olefin) (PMA)-based coating that is supplied to the microchannel in a toluene solution. The PMA reacts with 3-aminopropyltriethoxysilane groups linked to the glass surface to form a matrix that enables additional maleic anhydride groups to react with free amino groups on enzymes to give a mixed covalent,noncovalent immobilization support. Using a simple T-channel microfluidic design, with reaction channel dimensions of 200 ,m wide (at the center), 15 ,m deep, and 30 mm long giving a reaction volume of 90 nL, soybean peroxidase (SBP) was attached at an amount up to 0.6 ,g/channel. SBP-catalyzed oxidation of p -cresol was performed in aqueous buffer (with 20% [v/v], dimethylformamide) containing H2O2, with microfluidic transport enabled by electroosmotic flow (EOF). Michaelis,Menten kinetics were obtained with Km and Vmax values of 0.98 mM and 0.21 ,mol H2O2 converted/mg SBP per minute, respectively. These values are nearly identical to nonimmobilized SBP kinetics in aqueous,DMF solutions in 20-,L volumes in 384-well plates and 5-mL reaction volumes in 20-mL scintillation vials. These results indicate that SBP displays intrinsically native activity even in the immobilized form at the microscale, and further attests to the mild immobilization conditions afforded by PMA. Bienzymic and trienzymic reactions were also performed in the microfluidic biochip. Specifically, a combined Candida antarctica lipase B,SBP bienzymic system was used to convert tolyl acetate into poly(p -cresol), and an invertase,glucose oxidase SBP trienzymic system was used to take sucrose and generate H2O2 for SBP-catalyzed synthesis of poly(p -cresol). © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 20,28, 2003. [source]