Biological identity of nanomaterials: Opportunities and challenges

The emergence of nanoparticles (NPs) has attracted tremendous interest of the scientific community for decades due to their unique properties and potential applications in diverse areas, including drug delivery and therapy. Many novel NPs have been synthesized and used to reduce drug toxicity, improve bio-availability, prolong circulation time, control drug release, and actively target to desired cells or tissues. However, clinical translation of NPs with the goal of treating particularly challenging diseases, such as cancer, will require a thorough understanding of how the NP properties influence their fate in biological systems, especially in vivo. Many efforts have been paid to studying the interactions and mechanisms of NPs and cells. Unless deliberately designed, the NPs in contact with biological fluids are rapidly covered by a selected group of biomolecules especially proteins to form a corona that interacts with biological systems. In this view, the recent development of NPs in drug delivery and the interactions of NPs with cells and proteins are summarized. By understanding the protein-NP interactions, some guidelines for safety design of NPs, challenges and future perspectives are discussed.     

Omniphobic membranes for distillation: Opportunities and challenges

As an emerging thermal-driven membrane technology, membrane distillation (MD) has attracted immense attention for desalination and water purification. The membranes for MD generally have hydrophobic or superhydrophobic properties to enable vapor permeation without liquid passage (e.g., wetting). However, conventional MD membranes cannot undergo long term stable operations due to gradual wetting in practical applications where the feed solution often contains multiple low-surface tension contaminants (e.g., oil). Recently, omniphobic membranes repelling all sorts of liquids and typically having ultralow surface energy and re-entrant structures have been developed for robust MD to mitigate wetting and fouling. In this paper, we aim to provide a comprehensive review of recent progress on omniphobic membranes. Fundamentals, desirable properties, advantages and applications of omniphobic membranes are discussed. We also summarize the research efforts and methods to engineer omniphobic membranes. Finally, the challenges and future research directions on omniphobic membranes are discussed.     

Polyaniline-supported nano metal-catalyzed coupling reactions: Opportunities and challenges

Polyanilines (PANIs) can be easily prepared from the available and cheap anilines via the oxidative polymerization reactions. Owing to the coordination of nitrogen in the material with metals, PANIs are widely used as the support of nano metal catalysts. In comparison with inorganic supports, the nano metals on PANIs were firmly anchored via the coordination bond so that they are not easily to lose during the reaction process. Moreover, since PANIs are versatile materials and their chemical features can be adjusted by introducing functional groups onto the monomers, the catalytic activities of the prepared catalysts are tunable. During the past decade, PANIs-supported nano metal catalysts have been widely applied in a variety of coupling reactions. This review aims to summarize the recent advances and give a perspective.     

Magnesium complexes in hydroelementation and reduction catalysis: Opportunities and challenges

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Sustainability performance of polyethylene terephthalate,clarifying challenges and opportunities

Publications on polyethylene terephthalate (PET) continue to increase including the number of publications on recycling. PET is a versatile material with the ability to be remade from its polymer state through mechanical recycling and even back to its original monomer through advanced recycling. The scale of PET's use affords continued research and applications in improved recycling. Publications on new uses of discarded PET and the ability to clean and convert it into many forms including alternative materials are expanding with an attempt to complete circular use or improve the end of life. As indicated in life cycle assessment studies, increases in recycling lower the energy required to manufacture products. The future for PET will reduce energy demands further with the largest breakthroughs in recycling technologies and bio-sourced resins trending toward zero energy and carbon negative solutions. Opportunities remain for improvement in the use of PET with light weighting. The testing of new resins, development of bio-feedstocks, improvements in engineering, processing, recycling, and design continue to provide benefits. This review provides context for these developments.     

Opportunities and challenges in applying machine learning to voltammetric mechanistic studies

Voltammetry is a powerful tool for providing quantitative mechanistic information associated with a broad range of chemically or biologically important electron transfer processes. An important step in voltammetric data analysis is to compare experimental data with those derived by simulations based on a mechanism chosen by the experimenter to determine the ‘best fit’, which can be achieved either heuristically or by a computationally supported automated method. In recent years, machine learning methods have emerged as a powerful tool in mechanism classification and parametrisation, owing to the rapid increase in computing power and widespread accessibility of machine learning platforms. This opinion article gives an overview of the historical development and current status of machine learning in this field, highlights the opportunities and challenges, and predicts possible future directions.     

Recycling of bioplastics,their blends and biocomposites: A review

This review presents scientific findings concerning the recycling of bioplastics, their blends and thermoplastic biocomposites, with special focus on mechanical recycling of bio-based materials. The paper does not include bio-based commodity plastics such as bio-derived polyolefins that are identical to their petroleum-based counterparts and that can be recycled in the same way. During the past few years, recycling of biopolymers and their blends has been studied using both mechanical and chemical methods, whereas in biocomposites, the focus has been on mechanical recycling. This review goes through the findings on the recyclability of various materials, the strengths and weaknesses of applied methods, as well as the potential strategies and opportunities for future improvements. There are still many blends that have not been investigated for their recyclability. Information about commercially available blends containing bioplastics is summarised in the Appendix because of the importance of their possible effects on the conventional plastic recycling streams.     

Bioinspired synthesis as a potential green method for the preparation of nanomaterials: Opportunities and challenges

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Opportunities and challenges of high-pressure ion exchange chromatography for nuclide separation and enrichment

With the rapid development of the nuclear industry, more-stringent requirements are proposed for high-level radioactive waste liquid treatment and the enrichment of isotope products. High-pressure ion exchange chromatography has been widely accepted for the fine separation of elements and nuclides due to its advantages, such as high efficiency, environmental friendliness, ease of operation, and feasibility for large-scale industrial applications. Here, we summarized the evolution of high-pressure ion exchange chromatography and the relevant research progress in ion exchange equilibrium and related separation technology. The prospects for application of high-pressure ion exchange chromatography to rare earth elements, actinide elements and isotope separation were discussed. High-pressure ion exchange chromatography represents a promising strategy for the extraction of rare earth elements and actinide elements from high-level radioactive waste liquid, as well as being an effective method for the automated production of high purity isotope products with great environmental benefits.     

Biomacromolecules in microgels — Opportunities and challenges for drug delivery

This brief review aims at providing some illustrative examples on the interaction between microgels and biological macromolecules, with special focus on peptides and proteins, as well as current applications of such systems in drug delivery. In doing so, novel insights on factors affecting peptide/protein incorporation to, distribution within, and release from, sparsely cross-linked microgels are addressed, including effects of network charge and cross-linking density, as well as peptide/protein length/size, charge (distribution), and hydrophobicity. Effects of ambient conditions are also illustrated, with special focus on pH and ionic strength. Notably, factors precluding the application of microgel systems in biomacromolecular drug delivery, e.g., shell formation and incomplete drug release, are discussed, together with challenges and opportunities of these effects in the application of biomacromolecule/microgel systems in drug delivery.     

Opportunities and challenges of translating direct single impact electrochemistry to high-throughput sensing applications

In this review, we address the opportunities and challenges of single impact electrochemistry as a detection framework applicable beyond the research laboratory. Focusing on the direct detection of nanoparticles, we discuss several aspects essential to the transfer of this technique into applications for ultralow concentration sensing. We cover particle size–dependent sensor performance and engineering approaches for improving mass transfer via microfluidics. Furthermore, we address interfering phenomena such as aggregation, adsorption, and the effect of electrolyte composition.     

Thermosetting of wheat protein based bioplastics: modeling of mechanism and material properties

Structural investigation of gluten-glycerol blends subjected to heat-treatment was carried out by size-exclusion high performance liquid chromatography (SEC) and stress-strain tests. SEC is a valuable tool to investigate the size distribution of gluten protein chains, while the molecular weight between network junctions (M_e) can be estimated from the elastic plateau modulus. Wheat gluten aggregation upon thermosetting seems to proceed through direct covalent cross-linking between glutenin oligomers and the gluten macropolymer. The time course of the reaction, which showed a slow-down of the reaction rate with time, was described by a simple mechanistic model. The deceleration of the reaction rate was presumably due to the development of a three-dimensional protein network, which decreased the accessibility of reactive groups. The network formation could be evidenced separately by the decrease of M_e during the heat-treatment.     

Conversion of food industrial wastes into bioplastics

The usage of plastics in packaging and disposable products, and the generation of plastic waste, have been increasing drastically. Broader usage of biodegradable plastics in packaging and disposable products as a solution to environmental problems would heavily depend on further reduction of costs and the discovery of novel biodegradable plastics with improved properties. In the authors’ laboratories, various carbohydrates in the growth media, including sucrose, lactic acid, butyric acid, valeric acid, and various combinations of butyric and valeric acids, were utilized as the carbon (c) sources for the production of bioplastics byAlcaligenes eutrophus. As the first step in pursuit of eventual usage of industrial food wastewater as nutrients for microorganisms to synthesize bioplastics, the authors investigated the usage of malt wastes from a beer brewery plant as the C sources for the production of bioplastics by microorganisms. Specific polymer production yield by A. Latus DSM 1124 increased to 70% polymer/cell (g/g) and 32g/L cell dry wt, using malt wastes as the C source. The results of these experiments indicated that, with the use of different types of food wastes as the C source, different polyhydroxyal-kanoate copolymers could be produced with distinct polymer properties.     

Polylactic acid incorporated polyfurfuryl alcohol bioplastics: thermal,mechanical and curing studies

Biodegradable polyfurfuryl alcohol (PFA)-based bioplastics, containing 0.5% to 3% (w/v) dissolvable polylactic acid (PLA) fabric, were successfully fabricated with p-toluene sulphonic acid as an acid catalyst by casting method in a silicon mould. By incorporating PLA, the 1st step thermal curing time of acid-catalysed furfuryl alcohol decreased from 96 h to 22 h. The fabricated bioplastics were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and tensile testing to evaluate their structure and properties. The results revealed that PFA-based bioplastics with 0.5% PLA showed higher tensile strength as well as higher elongation at break compared to neat PFA-based bioplastics. Also, the thermal stability of PFA bioplastic at 0.5% PLA increased compared to neat PFA. A “green” and solvent-free method for incorporating PLA in PFA resin to fabricate PLA incorporated PFA-based bioplastics has been delineated in this work.     

Far-red triplet sensitized Z-to-E photoswitching of azobenzene in bioplastics

We report the first example of direct far-red triplet sensitized molecular photoswitching in a condensed phase wherein a liquid azobenzene derivative (Azo1) co-assembled within a liquid surfactant–protein film undergoes triplet sensitized Z-to-E photoswitching upon far-red/red light excitation in air. The role of triplet sensitization in photoswitching has been confirmed by quenching of sensitizer phosphorescence by Z-Azo1 and temperature-dependent photoswitching experiments. Herein, we demonstrate new biosustainable fabrication designs to address key challenges in solid-state photoswitching, effectively mitigating chromophore aggregation and requirement of high energy excitations by dispersing the photoswitch in the trapped liquid inside the solid framework and by shifting the action spectrum from blue-green light (450–560 nm) to the far-red/red light (740/640 nm) region.

We report the first example of direct far-red endothermic triplet sensitized Z-to-E photoswitching of azobenzene derivative (Azo1) in a condensed phase of a liquid Azo1 co-assembled within a liquid surfactant-protein bioplastic film in air.     

Thermoplastic processing of protein-based bioplastics: chemical engineering aspects of mixing,extrusion and hot molding

Proteins, as heteropolymers, offer a large range of possible interactions and chemical reactions. The thermoplastic behavior of proteins has been studied in order to produce bioplastics by thermal or thermomechanical processes such as mixing, extrusion or hot molding. The extrusion trials were performed by using a co-rotating twin-screw extruder, recording torque, temperature and die pressure. Batch mixing was done in a two blade counter-rotating mixer, with continuous recording of torque and product temperature. Proteins were alternatively extruded, mixed or hot molded under a large range of processing conditions. Protein aggregation during each process was estimated from the accumulation of SDS-insoluble protein fraction. Protein aggregation evidences a cross-linking reaction the activation energy of which was dependent on the thermoplastic process used. The increase in network density appears to be induced by the severity of the treatment: temperature and shear strongly affect the structural characteristics of the protein-based bioplastics.     

Recycling possibilities of bioplastics based on PLA/PHB blends

The study is focused on modelling the evaluation of recyclability of the biodegradable blend using multiple extrusion of selected composition of PLA/PHB blend which had been more deeply studied before. It was shown that the multiple extrusion reduces viscosity of the tested blend due to multiple thermomechanical stresses and the material was partially degraded. Partial degradation was demonstrated by measuring of molecular characteristics. The degree of degradation of the tested material was determined with relatively high accuracy after creating a colour space/viscosity. Multiple processing and subsequent degradation of the tested material did not negatively affect thermal properties, as well as strength characteristics of the blend. It was concluded that the biodegradable polymer blend of the PLA/PHB type is suitable for multiple processing and material recycling can be applied for this type of bioplastics.