Novel strategies for the synthesis of hydroxylated and carboxylated polystyrenes

Increasing Solvent Tolerance to Improve Microbial Production of Alcohols, Terpenoids and Aromatics

Fuels and polymer precursors are widely used in daily life and in many industrial processes. Although these compounds are mainly derived from petrol, bacteria and yeast can produce them in an environment-friendly way. However, these molecules exhibit toxic solvent properties and reduce cell viability of the microbial producer which inevitably impedes high product titers. Hence, studying how product accumulation affects microbes and understanding how microbial adaptive responses counteract these harmful defects helps to maximize yields. Here, we specifically focus on the mode of toxicity of industry-relevant alcohols, terpenoids and aromatics and the associated stress-response mechanisms, encountered in several relevant bacterial and yeast producers. In practice, integrating heterologous defense mechanisms, overexpressing native stress responses or triggering multiple protection pathways by modifying the transcription machinery or small RNAs (sRNAs) are suitable strategies to improve solvent tolerance. Therefore, tolerance engineering, in combination with metabolic pathway optimization, shows high potential in developing superior microbial producers.

Chitosan-grafted-poly(methacrylic acid)/graphene oxide nanocomposite as a pH-responsive de novo cancer chemotherapy nanosystem

The aim of this study was the design and development of a novel de novo drug delivery system for cancer chemotherapy. For this purpose, chitosan (CS) functionalized using phthalic anhydride followed by 4-cyano, 4-[(phenylcarbothioyl) sulfanyl] pentanoic acid as a chain transfer agent (CTA) to afford CS-CTA macroinitiator. The synthesized CS-CTA macroinitiator was then copolymerized with methacrylic acid (MAA) monomer using reversible addition-fragmentation chain transfer (RAFT) polymerization technique to produce chitosan-graft-poly(methacrylic acid) (CS-g-PMAA) graft copolymer. Afterward, graphene oxide (GO) nanosheets were incorporated into the synthesized copolymer through the physical interactions. The CS-g-PMAA/GO nanocomposite was loaded with doxorubicin hydrochloride (DOX) as a universal anticancer drug. The biocompatibility, DOX-loading capacity, and pH dependent drug release behavior of the developed nanocomposite were also investigated. As the experimental results, as well as superior biological and physicochemical features of CS and GO, we envision that the developed CS-g-PMAA/GO nanocomposite may be applied as de novo drug delivery nanosystem for cancer chemotherapy.