Thermoresponsive, stretchable, biodegradable and biocompatible poly(glycerol sebacate)-based polyurethane hydrogels

Thermoresponsive, stretchable, biodegradable and biocompatible polyester-based polyurethane (PEU) hydrogels, based on poly(glycerol sebacate) pre-polymer and poly(ethylene glycol)s of different molecular masses were synthesized by a facile solvent-based two-step method. The chemical and physical characteristics of the PEU hydrogels are tunable, enabling the design of various negatively thermosensitive, mechanically stable and biodegradable systems. The PEU hydrogels demonstrate reversible responses to a change in medium temperature from 5 °C to 37 °C, with the swelling ratio at equilibrium varying from 499% to 12%. The hydrogels have a tensile Young’s modulus, ultimate tensile strength and elongation at break in the range of 0.02–0.20 MPa, 0.05–0.47 MPa and 426–623%, respectively, and show high stretchability and full shape recovery after compression. These are similar to the mechanical properties of adipose tissues. In vitro degradation tests show mass losses of 8.7–16.3% and 10.7–20.7% without and with the presence of lipase enzyme for 31 days, respectively. In vitro cell tests show clear evidence that some of the PEU hydrogels are suitable for culturing adipose-derived stem cells and dermal fibroblasts and hence for future soft tissue regeneration. The functionalities of the PEU hydrogels were also evaluated for potential applications in drug delivery, thermal actuation and ultralow power generation. The results demonstrate the versatility of these PEU hydrogels for a variety of biomedical and engineering application

Poly (glycerol-sebacate) bioelastomers: 2. Synthesis using Brabender Plasticoder^® as a batch reactor

Poly (glycerol-sebacate) polymers are seen as useful materials for biomedical applications. In this article, poly (glycerol-sebacate) oligomers were synthesized by modifying a Brabender Plasticorder((R)) as a batch reactor. The samples collected over a reaction period of 5 h were characterized using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The number-average molecular weight (M-n) and weight-average molecular weight (M-w) of the oligoesters were determined using matrix-assisted laser desorption/ionization time-of-flight spectroscopy (MALDI-TOF). The polydispersity indices of these oligoesters produced were within bounds of current commercial polymers. The gel-point of the reaction was determined from the crossover point of the storage and loss moduli, and the reaction rate constant was calculated using the torque data of the rheometer. The kinetic rate constant and the extent of the reaction in the Brabender were higher than the corresponding values obtained from the conventional laboratory reaction process. The challenges and possibilities in scaling up a batch process to a continuous process (e.g., reactive extrusion) are discussed. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42852

Compatibilization of starch-polyester blends using reactive extrusion

Maleic anhydride (MA) and dicumyl peroxide (DCP) were used as crosslinking agent and initiator respectively for blending starch and a biodegradable synthetic aliphatic polyester using reactive extrusion. Blends were characterized using dynamic mechanical and thermal analysis (DMTA). Optical micrographs of the blends revealed that in the optimized blend, starch was evenly dispersed in the polymer matrix. Optimized blends exhibited better tensile properties than the uncompatibilized blends. Xray photoelectron spectroscopy supported the proposed structure for the starch-polyester complex. Variation in the compositions of crosslinking agent and initiator had an impact on the properties and color of the blends

Network pharmacology based anti-diabetic attributes of bioactive compounds from Ocimum gratissimum L. through computational approach

The present research was framed to determine the key compounds present in the plant Ocimum gratissimum L. targeting protein molecules of Diabetes Mellitus (DM) by employing In-silico approaches. Phytochemicals previously reported to be present in this herb were collated through literature survey and public phytochemical databases, and their probable targets were anticipated using BindingDB (p ≥ 0.7). STRING and KEGG pathway databases were employed for pathway enrichment analysis. Homology modelling was executed to elucidate the structures of therapeutic targets. Further, Phytocompounds from O. gratissimum were subjected for docking with four therapeutic targets of DM by using AutoDock vina through POAP pipeline implementation. 30 compounds were predicted to target 136 protein molecules including aldose reductase, DPP4, alpha-amylase, and alpha-glucosidase. Neuroactive ligand-receptor interaction, MAPK, PI3K-Akt, starch and insulin resistance were predicted to have potentially modulation by phytocompounds. Based on the phytocompound’s binding score with the four targets of DM, Rutin scored the lowest binding energy (-11 kcal/mol) with Aldose reductase by forming 17 intermolecular interactions. In conclusion, based on the network and binding score, phytocompounds from O. gratissimum have a synergistic and considerable effect in the management of DM via multi-compound, multi-target, and multi-pathway mechanisms

Structural characteristics of bagasse furfural residue and its lignin component: An NMR, Py-GC/MS, and FTIR study

Commercial furfural, an important platform chemical, is produced from acid hydrolysis of lignocellulosic biomass. The manufacturing processes are inherently inefficient, and so it is necessary to value add to substantial amounts of residue obtained. The structural features of bagasse furfural residue and the lignins extracted from it by three NaOH treatments have been studied in order to understand the transformations that occurred by these treatments. 2D-NMR and Py-GC/MS of the furfural residue revealed that it contains mostly lignin and depolymerized cellulose moieties and the complete absence of xylans as a result of their hydrolysis during the furfural production process. In addition, the analyses revealed that the furfural residue contains 44% of H-type lignin units, in comparison to 11% for bagasse, and most of the lignin interunit linkages present in bagasse have disappeared. The pyrograms show that the furfural residue produced unusually high phenol content, which was attributed to the high levels of “H-type” units present in this lignin. The proportion of functional groups, particularly total OH aliphatic groups, where significantly lower in the extracted lignins compared to soda lignin obtained by the normal pulping process. The highest severity of the NaOH extraction process reduced the amount of reactive functional groups present in the lignin, though the S/G ratios of ∼1.1 were independent of the extraction method. The three lignins have high proportions of “H-units” (around 36–37%), which gives them special properties for different applications, particularly in the production of phenolic resins

Preparation and characterization of composites from starch with sugarcane bagasse nanofibres

This paper reports on the results of using unbleached sugar cane bagasse nanofibres (average diameter 26.5 nm; aspect ratio 247 assuming a dry fibre density of 1,500 kg/m3) to improve the physico-chemical properties of starch-based films. The addition of bagasse nanofibres (2.5 to 20 wt%) to modified potato starch (i.e. soluble starch) reduced the moisture uptake by up to 17 % at 58 % relative humidity. The film’s tensile strength and Young’s modulus increased by up to 100 % (3.1 to 6.2 MPa) and 300 % (66.3 to 198.3 MPa) respectively with 10 and 20 wt% fibre addition. However, the strain at yield dropped by 50 % for the film containing 10 wt% fibre. Models for composite materials were used to account for the strong interactions between the nanofibres and the starch matrix. The storage and loss moduli as well as the glass transition temperature (Tg) obtained from dynamic mechanical thermal analysis, were increased with the starch-nanofibre films indicating decreased starch chain mobility due to the interacting effect of the nanofibres. Evidence of the existence of strong interactions between the starch matrix and the nanofibres was revealed from detailed Fourier transform infra-red and scanning electron microscopic evaluation