Comprehensive Study of Free Radical Copolymerization Using a Monte Carlo Simulation Method, 1

Summary: In order to investigate the influence of reactivity ratios and initial feed composition on the microstructure of macromolecules in free radical copolymerization, a comprehensive study was carried out using a Monte Carlo simulation method. As a result, a new procedure was introduced to modify the works of others on the initiation step. The variation of the copolymer composition and the fashion of the arrangement of monomers in simulated chains were evaluated as a function of copolymerization parameters. The model was capable of monitoring any change in azeotropy as well as the magnitude and direction of composition drift from the azeotrope point. The maximum reachable conversion (MRC) was predicted for different combinations of initial feed compositions and reactivity ratios. According to the simulation results, a critical conversion where the macromolecules produced inherited the maximum allowed alternation was obtained for the reactivity ratios given.

Change of sequence distribution of simulated copolymer chains with conversion for various initial feed compositions on a triangular graph (r_A = 0.5, r_B = 0.9).     

Mucin-Inspired Single-Chain Polymer (MIP) Fibers as Potent SARS-CoV-2 Inhibitors

Mucins are the key component of the defensive mucus barrier. They are extended fibers of very high molecular weight with diverse biological functions depending strongly on their specific structural parameters. Here, we present a mucin-inspired nanostructure, produced via a synthetic methodology to prepare methacrylate-based dendronized polysulfates ( MIP-1 ) on a multi gram-scale with high molecular weight (MW=450 kDa) and thiol end-functionalized mucin-inspired polymer ( MIP ) via RAFT polymerization. Cryo-electron tomography (Cryo-ET) analysis of MIP-1 confirmed a mucin-mimetic wormlike single-chain fiber structure (length=144±59 nm) in aqueous solution. This biocompatible fiber showed promising activity against SARS-CoV-2 and its mutant strain, with a remarkable low half maximal (IC₅₀) inhibitory concentration (IC₅₀=10.0 nM). Additionally, we investigate the impact of fiber length on SARS-CoV-2 inhibition by testing other functional polymers ( MIPs ) of varying fiber lengths.     

The Effect of Rainbow Trout (Oncorhynchus mykiss) Collagen Incorporated with Exo-Polysaccharides Derived from Rhodotorula mucilaginosa sp. on Burn Healing

Burn is one of the physically debilitating injuries that can be potentially fatal; therefore, providing appropriate coverage in order to reduce possible mortality risk and accelerate wound healing is mandatory. In this study, collagen/exo-polysaccharide (Col/EPS 1–3%) scaffolds are synthesized from rainbow trout (Oncorhynchus mykiss) skins incorporated with Rhodotorula mucilaginosa sp. GUMS16, respectively, for promoting Grade 3 burn wound healing. Physicochemical characterizations and, consequently, biological properties of the Col/EPS scaffolds are tested. The results show that the presence of EPS does not affect the minimum porosity dimensions, while raising the EPS amount significantly reduces the maximum porosity dimensions. Thermogravimetric analysis (TGA), FTIR, and tensile property results confirm the successful incorporation of the EPS into Col scaffolds. Furthermore,the biological results show that the increasing EPS does not affect Col biodegradability and cell viability, and the use of Col/EPS 1% on rat models displays a faster healing rate. Finally, histopathological examination reveals that the Col/EPS 1% treatment accelerates wound healing, through greater re-epithelialization and dermal remodeling, more abundant fibroblast cells and Col accumulation. These findings suggest that Col/EPS 1% promotes dermal wound healing via antioxidant and anti-inflammatory activities, which can be a potential medical process in the treatment of burn wounds.