Keywords : crosslinking

Riboflavin-UVA gelatin crosslinking: Design of a biocompatible and thermo-responsive biomaterial with enhanced mechanical properties for tissue engineering

Juan Manuel Galdopórpora; Claudio Javier Perez; María Victoria Tuttolomondo; Martín Federico Desimone

Advanced Materials Letters, 2019, Volume 10, Issue 5, Pages 324-328
DOI: 10.5185/amlett.2019.2210

The main objective of this study is to develop an economic, environmentally friendly and malleable biomaterial for tissue engineering applications. Water and glycerol have been used as solvents for the gelatin hydrogel synthesis. This solvent mixture led to a biomaterial with improved thermal properties. Indeed, a 16°C increase in thermal transition temperature was achieved. Furthermore, to enhance mechanical properties, riboflavin was used as a crosslinking agent. Chemical crosslinking step was initiated with UV radiation to obtain riboflavin radical polymerization of gelatin chains, hence, rheological properties of gelatin hydrogel were improved. Thus, Gelatin-UV-Riboflavin hydrogel showed good swelling and increased mechanical properties, obtaining a novel material for drug delivery and medical purposes.

Enzymatic Ring Opening Polymerization Of É›-caprolactone By Using A Novel Immobilized Biocatalyst

Nurefsan Gokalp; Cansu Ulker; Yuksel Avcibasi Guvenilir

Advanced Materials Letters, 2016, Volume 7, Issue 2, Pages 144-149
DOI: 10.5185/amlett.2016.6059

In this study, an amorphous silica material was used as a carrier to immobilize Candida antarctica lipase B (CALB) by crosslinking method for ring opening polymerization of É›-caprolactone (É›-CL). The optimum temperature, enzyme concentration and time period were investigated for poly(É›-caprolactone) (PCL) synthesis via ring opening polymerization of É›-CL catalyzed by immobilized CALB (IMCALB). Molecular weights of PCLs were determined by using gel permeation chromatography (GPC) and hydrogen nuclear magnetic resonance ( 1 H-NMR) analysis. The surface morphologies of PCLs were analyzed by scanning electron microscopy (SEM). Besides, PCLs were successfully characterized by fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The results showed that the immobilized lipase by crosslinking method via glutaraldehyde possessed good activity and stability. By using this immobilized enzyme, high molecular weights and monomer conversions of PCLs were achieved about 9000 g/mol and     90 %, respectively. This work has showed that activity of CALB increased about 17 % dramatically after immobilization process, and PCL was synthesized via enzymatic polymerization catalyzed this novel enzyme, which provides an effective method for conducting “green polymer chemistry”. 

Low Molecular Weight Palmitoyl Chitosan: Synthesis, characterization And Nanoparticle Preparation

Yogesh M. Choudhari; Sachin V. Detane; Sushant S. Kulthe; Chandrakant C. Godhani; Nazma N. Inamdar; Seema M. Shirolikar; Lalit C. Borde; Vishnukant K. Mourya

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 487-492
DOI: 10.5185/amlett.2012.icnano.203

Low molecular weight chitosan (LMWC) exhibits higher water solubility and produces nanoparticles of fairly low particle size. However, poor drug loading and shorter circulation time in body limits its application in preparation of nanoparticles. Acylation of LMWC ensures extended circulation of nanoparticles in body and hence enhanced bioavailability of the drug. We therefore synthesized the acylated LMWC using palmitoyl chloride and confirmed its synthesis by FTIR and NMR spectroscopy. The nanoparticles of LMWC and low molecular weight palmitoyl chitosan (LMWPC) were prepared by miniemulsion and chemical crosslinking method using glutaraldehyde and 5-fluorouracil (5FU) as a model drug. The nanoparticles were evaluated for particle size, zeta potential, morphology, drug loading and drug release. TEM analysis revealed nanosize and spherical nature of the particles. The palmitoyl chain of LMWPC increased particle size from 83.2±2.5 nm to 93.4±3.2 nm whereas zeta potential of nanoparticles decreased from 12.5±2.2 mV to 4.2±1.1 mV due to diminished amino groups of LMWPC as a result of acylation. The drug loading in nanoparticles was increased from 13.8±0.95% to 30.2±1.9%. LMWC showed 80±2.08% as maximum drug released in 10 h while only 52.3±2.14% was released in 24 h for LMWPC. Hence, LMWPC nanoparticles ensure increased drug loading capacity and sustained drug release profile without significant change in particle size.