Application of Molecularly Imprinted Polymers in the Analysis of Waters and Wastewaters

The increase of the global population and shortage of renewable water resources urges the development of possible remedies to improve the quality and reusability of waste and contaminated water supplies. Different water pollutants, such as heavy metals, dyes, pesticides, endocrine disrupting compounds (EDCs), and pharmaceuticals, are produced through continuous technical and industrial developments that are emerging with the increasing population. Molecularly imprinted polymers (MIPs) represent a class of synthetic receptors that can be produced from different types of polymerization reactions between a target template and functional monomer(s), having functional groups specifically interacting with the template; such interactions can be tailored according to the purpose of designing the polymer and based on the nature of the target compounds. The removal of the template using suitable knocking out agents renders a recognition cavity that can specifically rebind to the target template which is the main mechanism of the applicability of MIPs in electrochemical sensors and as solid phase extraction sorbents. MIPs have unique properties in terms of stability, selectivity, and resistance to acids and bases besides being of low cost and simple to prepare; thus, they are excellent materials to be used for water analysis. The current review represents the different applications of MIPs in the past five years for the detection of different classes of water and wastewater contaminants and possible approaches for future applications.     

Towards a Synthetic Biology Toolset for Metallocluster Enzymes in Biosynthetic Pathways: What We Know and What We Need

Microbes are routinely engineered to synthesize high-value chemicals from renewable materials through synthetic biology and metabolic engineering. Microbial biosynthesis often relies on expression of heterologous biosynthetic pathways, i.e., enzymes transplanted from foreign organisms. Metallocluster enzymes are one of the most ubiquitous family of enzymes involved in natural product biosynthesis and are of great biotechnological importance. However, the functional expression of recombinant metallocluster enzymes in live cells is often challenging and represents a major bottleneck. The activity of metallocluster enzymes requires essential supporting pathways, involved in protein maturation, electron supply, and/or enzyme stability. Proper function of these supporting pathways involves specific protein–protein interactions that remain poorly characterized and are often overlooked by traditional synthetic biology approaches. Consequently, engineering approaches that focus on enzymatic expression and carbon flux alone often overlook the particular needs of metallocluster enzymes. This review highlights the biotechnological relevance of metallocluster enzymes and discusses novel synthetic biology strategies to advance their industrial application, with a particular focus on iron-sulfur cluster enzymes. Strategies to enable functional heterologous expression and enhance recombinant metallocluster enzyme activity in industrial hosts include: (1) optimizing specific maturation pathways; (2) improving catalytic stability; and (3) enhancing electron transfer. In addition, we suggest future directions for developing microbial cell factories that rely on metallocluster enzyme catalysis.     

Polymer Scaffolds for Biomedical Applications in Peripheral Nerve Reconstruction

The nervous system is a significant part of the human body, and peripheral nerve injury caused by trauma can cause various functional disorders. When the broken end defect is large and cannot be repaired by direct suture, small gap sutures of nerve conduits can effectively replace nerve transplantation and avoid the side effect of donor area disorders. There are many choices for nerve conduits, and natural materials and synthetic polymers have their advantages. Among them, the nerve scaffold should meet the requirements of good degradability, biocompatibility, promoting axon growth, supporting axon expansion and regeneration, and higher cell adhesion. Polymer biological scaffolds can change some shortcomings of raw materials by using electrospinning filling technology and surface modification technology to make them more suitable for nerve regeneration. Therefore, polymer scaffolds have a substantial prospect in the field of biomedicine in future. This paper reviews the application of nerve conduits in the field of repairing peripheral nerve injury, and we discuss the latest progress of materials and fabrication techniques of these polymer scaffolds.     

Alkenyl Boronates: Synthesis and Applications

Organoboron compounds have become one of the most versatile building blocks in organic synthesis owing to their accessible and efficient conversion into many different functional groups. In particular, alkenyl boronates have received a great deal of attention as very reactive substrates in Suzuki–Miyaura cross‐coupling reactions. Accordingly, efforts towards the development of efficient methods to prepare this type of compound are ongoing. In this contribution, the progress in the search for synthetic routes for alkenyl boronates and their use in a variety of organic transformations is accounted.     

Graft copolymerization of hydroxyethyl cellulose with solketal acrylate: Preparation and characterization for moisture absorption application

In this work, we reported the preparation of a novel biomaterial, by graft-polymerization of 2-2-dimethyl-1-3-dioxolan-4-yl methyl acrylate (solketalacrylate, DMDMA) on hydroxyethyl cellulose (HEC) using KPS as initiator. Several experiments were performed to found the optimum conditions for the preparation of this biopolymer, by varying the time of the reaction as well as the initiator and the monomer ratio. Results showed that the highest grafting yield was 25%, obtained after 72?minutes at 65?°C, using THF as solvent. The structure of the grafted copolymer was confirmed by X-ray diffraction patterns which showed, besides the characteristic peaks of HEC at 2θ?=?31.74° and 44.63° a new peak at 2θ?=?30.72° related to an organized structure of the grafted polymer on the HEC backbone. The DSC analysis showed a single glass transition temperature Tg, intermediate between the corresponding values for HEC and neat poly(solketal acrylate). Moreover, the grafted biomaterial presented two-fold more moisture absorption ability by comparison with HEC, making this new synthetic biomaterial highly promising for dryness applications. In our knowledge, the synthesized monomer: 2-2-dimethyl-1-3-dioxolan-4-yl methyl acrylate, (solketal acrylate, DMDMA), has never been grafted on the HEC backbones before that is what makes the novelty of the present work.     

Synthesis of 3,4‐Fused Tricyclic Indoles Using 3‐Alkylidene Indolines as Versatile Precursors

In this personal account, our recent studies of novel synthetic methods of 3,4‐fused tricyclic indole derivatives using 3‐alkylidene indoline derivatives as versatile precursors are discussed. Two types of cascade reactions producing 3,4‐fused tricyclic 3‐alkylidene indolines were developed based on a palladium‐catalyzed intramolecular Heck insertion to an allene‐allylic amination cascade and a platinum‐catalyzed intramolecular Friedel‐Crafts type C?H coupling‐allylic amination cascade. Furthermore, three types of 3,4‐fused tricyclic indoles were accessible from a single 3‐alkylidene indoline precursor via acid‐promoted olefin isomerization or oxidative treatments. The application of the developed methods to the synthesis of natural products bearing a 3,4‐fused tricyclic indole skeleton, (?)‐aurantioclavine, fargesine, and synthetic studies of dragmacidin E are also highlighted.     

Koenigs–Knorr Glycosylation Reaction Catalyzed by Trimethylsilyl Trifluoromethanesulfonate

The discovery that traditional silver(I)-oxide-promoted glycosidations of glycosyl bromides (Koenigs–Knorr reaction) can be greatly accelerated in the presence of catalytic trimethylsilyl trifluoromethanesulfonate (TMSOTf) is reported. The reaction conditions are very mild that allowed for maintaining a practically neutral pH and, at the same time, providing high rates and excellent glycosylation yields. In addition, unusual reactivity trends among a series of differentially protected glycosyl bromides were documented. In particular, benzoylated α-bromides were much more reactive than their benzylated counterparts under these conditions.