Chemical Modification Methods Research Articles

Redox-neutral, metal-free tryptophan labeling of polypeptides in hexafluoroisopropanol (HFIP).

Despite the unmet needs for chemical tools to study biological roles of tryptophan in living systems, there has been a lack of chemical modification methods for tryptophan residues that can be used in cellular environments. Driven by a preliminary computational study of our previous research, this work experimentally examined our hypotheses to translate the metal-catalyzed tryptophan modification method in hexafluoroisopropanol (HFIP) into a metal-free process. While one of the hypotheses merely confirmed the superiority of the thiophene-ethanol reagent developed in the previous report, the second hypothesis resulted in the identification of a trifluoroborate salt and an acidic ionic liquid as alternatives for the catalysis. Labeling of lysates of a human cell line was achieved with the acidic ionic liquid catalyst, where negative impacts of the tryptophan labeling and HFIP medium on the cellular samples were apparently insignificant. Because the labeling process does not require any redox mediators and is a formal redox-neutral reaction, the metal-free approach would be of use for tryptophan biology research potentially related to their various redox roles.

The Effect of a Low Degree of Fluorine Substitution on Cotton Fiber Properties

AbstractCellulose modification often employs chemical processes to tailor its properties and functionalities to fit the demands of a wide range of applications, maximizing its potential as a versatile and sustainable material. From both synthetic and environmental standpoints, one of the ultimate goals is to achieve significant modifications to enhance the end properties of the cellulose while minimizing the number of modified building blocks. The current study demonstrates that a synthetic glucose derivative, 6‐deoxy‐6‐fluoro‐glucose (6F‐Glc), fed into the fertilized cotton ovules, resulted in the accumulation of fluorine inside the cotton fibers with no apparent alteration to their morphology or development. These fibers exhibited a degree of substitution of 0.006, which is 170 times lower than that reported for chemical methods for cellulose modification. However, the physical characterization of the modified fibers showed a surprisingly large impact of this low‐level modification on the cellulose structure (e.g., hydrogen bonding network rearrangement) and a modest increase in the mechanical properties of the fibers. The obtained results exemplify the use of biological systems to introduce low quantities of new functionalities while maximizing the impact on fiber properties.

Preparation of CNTs/SCF reinforcement using multiple continuous surface treatments to achieve synergistic improvement of epoxy resin-based composites interfacial properties: Towards industrial production of carbon fiber surface treatment

The silane/maleimide co-modified waterborne polyurethane (WPU-M-S) sizing agent and furan-functionalized carbon nanotubes (CNTs-FA) were prepared through chemical modification method. The continuous grafting of carbon nanotubes (CNTs) was realized on the carbon fiber surface by multiple continuous surface treatments, including electrochemical anodizing (EAO), sizing, and chemical grafting of CNTs. The stable physical and chemical connection between carbon fiber, sizing agent, and resin was constructed through the preparation of CNTs/SCF reinforcement. The results of different surface treatment processes such as ultrasound and CNTs grafting process were contrastively studied in terms of surface morphology, microstructure, and mechanical properties. It is reflected that carbon fiber grafted with CNTs-FA (CNTs/SCF) that were prepared by ultrasound assisted chemical grafting provide optimal wettability and interfacial performance. The interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) of CNTs/SCF reinforced epoxy resin composites are 115.37 % and 93.91 % higher than those of the untreated carbon fiber (UCF), respectively. The synergistic improvement mechanism of reinforcement on carbon fiber reinforced epoxy resin composites interfacial properties was proposed. This research provides a multiple continuous surface treatment technology that matches the industrial production of carbon fiber to prepare CNTs/SCF reinforcement.

Fabrication of multi-functional biodegradable liquid mulch utilizing xyloglucan derived from tamarind waste for agricultural application

Biodegradable liquid mulch is considered a promising alternative to plastic mulch for sustainable agriculture. This work proposed a xyloglucan-based liquid mulch with multi-function using a combination of chemical modification and blending methods. The esterification product of tamarind xyloglucan (TXG) from forestry wastes was synthesized with benzoic anhydride (BA). The effect of esterification modification was investigated, and BA-TXG was utilized as a film-forming and sand-fixation agent. The rheological properties, thermal stability, and hydrophobicity were improved following esterification. Additionally, waterborne polyurethane and urea were incorporated into the mulch to enhance its mechanical strength (23.28 MPa, 80.71 %), and homogeneity, as well as improve its nutritive properties. The xyloglucan-based liquid mulch has excellent UV protection, a high haze value (approximately 90 %), and retains water at a rate of 80.45 %. SEM and immersion experiment showed the effect of xyloglucan-based liquid mulch on sustainable sand-fixation. Moreover, the liquid mulch treatment demonstrated an impressive germination rate of 83.8 % and degradation rate of 51.59 % (60 days). The modified polysaccharide film increases stability and slows down the degradation rate. Tamarind xyloglucan-based liquid mulch exhibits powerful and diverse optical properties as well as sand fixation functions, indicating their great potential in sustainable agriculture as an alternative to plastic mulch.

The Art of Exploring Diatom Biosilica Biomaterials: From Biofabrication Perspective.

Diatom is a common single-cell microalgae with large species and huge biomass. Diatom biosilica (DB), the shell of diatom, is a natural inorganic material with a micro-nanoporous structure. Its unique hierarchical porous structure gives it great application potential in drug delivery, hemostat materials, and biosensors, etc. However, the structural diversity of DB determines its different biological functions. Screening hundreds of thousands of diatom species for structural features of DB that meet application requirements is like looking for a needle in a seaway. And the chemical modification methods lack effective means to control the micro-nanoporous structure of DB. The formation of DB is a typical biomineralization process, and its structural characteristics are affected by external environmental conditions, genes, and other factors. This allows to manipulate the micro-nanostructure of DB through biological regulation method, thereby transforming the screening mode of the structure function of DB from a needle in a seaway to biofabrication mode. This review focuses on the formation, biological modification, functional activity of DB structure, and its application in biomaterials field, providing regulatory strategies and research idea of DB from the perspective of biofabrication. It will also maximize the possibility of using DB as biological materials.

A Comprehensive Review of Surface Modification Techniques for Enhancing the Biocompatibility of 3D-Printed Titanium Implants

The advent of three-dimensional (3D) printing technology has revolutionized the production of customized titanium (Ti) alloy implants. The success rate of implantation and the long-term functionality of these implants depend not only on design and material selection but also on their surface properties. Surface modification techniques play a pivotal role in improving the biocompatibility, osseointegration, and overall performance of 3D-printed Ti alloy implants. Hence, the primary objective of this review is to comprehensively elucidate various strategies employed for surface modification to enhance the performance of 3D-printed Ti alloy implants. This review encompasses both conventional and advanced surface modification techniques, which include physical–mechanical methods, chemical modification methods, bioconvergence modification technology, and the functional composite method. Furthermore, it explores the distinct advantages and limitations associated with each of these methods. In the future, efforts in surface modification will be geared towards achieving precise control over implant surface morphology, enhancing osteogenic capabilities, and augmenting antimicrobial functionality. This will enable the development of surfaces with multifunctional properties and personalized designs. By continuously exploring and developing innovative surface modification techniques, we anticipate that implant performance can be further elevated, paving the way for groundbreaking advancements in the field of biomedical engineering.

Tuneable Plasmonic Resonances Of A Dynamic Thin Film Of Ultrasmall Nanocrystals Modified In the Anti-Galvanic Reduction Process.

Ultrasmall gold nanoparticles (NPs) have revolutionized nanotechnology as they are an excellent starting substrate for the synthesis of organic-inorganic hybrid materials with photonic or energy conversion applications, often with a responsive nature. However, ultrasmall NPs do not sustain plasmonic resonances, preventing their use in plasmon-related applications. In the presented work, we show a method of chemical modification of ultrasmall gold nanoparticles in order to fabricate dynamically controlled plasmonic thin films. For this purpose, we used the Anti-Galvanic Reduction process (AGR) to modify the surface of small gold nanoparticles, inducing plasmonic properties without notable size increases. Au@Ag NPs are then modified with liquid crystal-like organic ligands. The obtained NPs can assemble into densely packed films with long-range order and temperature-dependent structural properties. Namely, we detect two, fully reversible phase transitions between the hexagonal and cubic symmetries. The combination of AGR and organic surface modifications enabled us to demonstrate the possibility of managing plasmonic properties in the thin film of ~2 nm diameter metallic NPs.

Micropillars in Biomechanics: Role in Guiding Mesenchymal Stem Cells Differentiation and Bone Regeneration

AbstractEfficient bone repair relies on biomaterials that exhibit superior biocompatibility and enhanced osteogenic capabilities. In recent, micropatterning technology has emerged as a robust strategy for directing stem cell differentiation, offering a notable shift from traditional chemical induction or genetic modification methods by providing environmental cues to regulate cellular behavior. Among the various types of microstructures, micropillars have garnered significant attention due to their adjustable properties and high‐throughput experimental capabilities. These structures play a pivotal role in governing nuclear deformation and deciphering cellular responses to biomechanical cues. In this comprehensive review, the influence of micropillars on mesenchymal stem cells (MSCs), drawing upon two decades of research findings is critically assessed. The study comprehensively evaluates how micropillar substrates impact crucial cellular processes such as deformation, migration, adhesion, and ultimately, MSC fate determination toward an osteogenic lineage. By synthesizing and analyzing past studies, the potential regulatory mechanisms through which micropillars modulate MSC behavior are aimed to be elucidated. Furthermore, the utility of micropillars as a cutting‐edge biomechanical detection tool and platform for investigating cellular behaviors is explored. By projecting future applications, the review highlights the growing significance of micropillars in the dynamic field of biomechanics, underscoring their transformative potential in tissue engineering and regenerative medicine.

Selenium Modification of Natural Products and Its Research Progress.

The selenization of natural products refers to the chemical modification method of artificially introducing selenium atoms into natural products to interact with the functional groups in the target molecule to form selenides. Nowadays, even though scientists in fields involving organic selenium compounds have achieved numerous results due to their continuous investment, few comprehensive and systematic summaries relating to their research results can be found. The present paper summarizes the selenization modification methods of several kinds of important natural products, such as polysaccharides, proteins/polypeptides, polyphenols, lipids, and cyclic compounds, as well as the basic principles or mechanisms of the selenizing methods. On this basis, this paper explored the future development trend of the research field relating to selenized natural products, and it is hoped to provide some suggestions for directional selenization modification and the application of natural active ingredients.

From Natural Insulin to Designed Analogs: A Chemical Biology Exploration.

Since its discovery in 1921, insulin has been at the forefront of scientific breakthroughs. From its amino acid sequencing to the revelation of its three-dimensional structure, the progress in insulin research has spurred significant therapeutic breakthroughs. In recent years, protein engineering has introduced innovative chemical and enzymatic methods for insulin modification, fostering the development of therapeutics with tailored pharmacological profiles. Alongside these advances, the quest for self-regulated, glucose-responsive insulin remains a holy grail in the field. In this article, we highlight the pivotal role of chemical biology in driving these innovations and discuss how it continues to shape the future trajectory of insulin research.

The first electrochemical N-arylation of chitosan. Antibacterial effect of novel cationic chitosan derivatives

In this study, we present the first electrochemical N-arylation of chitosan, which serves as a straightforward and convenient method for chemical modification of chitosan under mild conditions. Importantly, this method avoids any undesirable depolymerization of the polysaccharide backbone. Through this process, we successfully synthesized chitosan derivatives with varying molecular weights: low, medium, and high. These derivatives exhibited different degrees of substitution, with values of approximately 20 %, 30 %, and 65 %, respectively. Our elaborately designed polymers possess excellent water solubility across a broad pH range, ranging from strongly alkaline to strongly acidic. Furthermore, we conducted an investigation into the antimicrobial activity of the synthesized derivatives against two bacterial strains, namely S. aureus and E. coli. We found that the antimicrobial effectiveness of the polymers strongly relies on both the degree of substitution and the molecular weight of the derivatives. Notably, derivatives with a high degree of substitution and low molecular weight exhibited the most potent antimicrobial activity. Additionally, we explored the formation of nanoparticles through ionic gelation using highly active antimicrobial derivatives. These nanoparticles displayed an even greater antibacterial effect, comparable to that of commercially available antibiotics. Overall, our findings highlight the significance of electrochemical N-arylation as a viable approach for modifying chitosan, yielding chitosan derivatives with desirable properties for potential applications in various fields, particularly in antimicrobial and nanomedicine domains.

Significance of Chemically Derivatized Starch as Drug Carrier in Developing Novel Drug Delivery Devices

Abstract: Delivery of therapeutics using synthetic polymers is challenging due to toxicity, immunogenicity and impaired bioavailability following administration. However, natural polymers are being explored as safe for their use as a substitute for synthetic polymers. In the past three decades, the biomaterials like starches have been applied to impart an imperative role in delivering therapeutics. There is an increased focus on finding new sources of starches and their modifications. Hence, the derivatization of starches has become necessary to achieve desired properties. The modifications to native starch systems are being investigated to improve solubility, stability, bioavailability, etc., of an incorporated drug (s) and lower-down induced toxicities. All these requirements have led to the use of modified starches in the drug delivery of bioactive component(s). This review explores the current state of knowledge about starch structure and chemical modification methods from perspectives. It integrates aspects of its use in developing drug delivery devices like tablets, hydrogel, and patches. The information provided in this review may be applied as a reference for future chemically modified starch as excipients in drug carrier studies.

Design of photocatalytic self-cleaning poly (arylene ether nitrile)/nitrogen-doped Bi2O2CO3 composite membrane for emulsified oily wastewater purification

Membrane separation technique offers unique advantages for treating the emulsified oily wastewater with the oil droplet diameter less than 20 µm. However, the complicated membrane fouling originating from oils and soluble matters pose the huge challenges to membrane separation technique, which has stimulated the development of advanced membrane materials. Herein, we reported the photocatalytic and super-wetting poly (arylene ether nitrile) (PEN) fibrous composite membrane with high permeability and enhanced anti-fouling ability. The nitrogen-doped Bi2O2CO3 (N-Bi2O2CO3) was prepared by low-temperature chemical modification method and modified by dopamine (DA)-polyethyleneimine (PEI), which was further self-assembled on porous PEN support backbone. The hydrophilicity provided by the cross-linking reaction between PDA and PEI and micro-/nano- rough surface constructed by the flower-like N-Bi2O2CO3 contributed to the super wetting properties (WCA=0°, UOCA>150°), which imparted the membrane with ultra-low oil adhesion. In particular, the arrangement of flower-like N-Bi2O2CO3 effectively regulated the water channel of membrane, further increasing the permeate flux. Therefore, the fibrous composite membranes showed superior separation flux (632.79–762.81 L·m−2·h−1) and separation efficiency (>99.16%) for various oil-in-water emulsions, even under harsh conditions (90 ℃ and 2 M NaCl solution). More importantly, the N-Bi2O2CO3 rendered the membrane excellent degradation rates for various dyes (MO: 95.53%, MeB: 96.40%, CV: 96.45%, CR: 87.14%), achieving favorable photocatalytic self-cleaning ability. This work opens an alternative strategy to fabricate fibrous composite membrane with synergistically enhanced anti-fouling for the treating complicated emulsified oily wastewater in petrochemical industry.

Chemical Modification of Polysaccharides: A Review of Synthetic Approaches, Biological Activity and the Structure-Activity Relationship.

Natural polysaccharides are macromolecular substances with great potential owing to their wide biological activity and low toxicity. However, not all polysaccharides have significant pharmacodynamic activity; hence, appropriate chemical modification methods can be selected according to the unique structural characteristics of polysaccharides to assist in enhancing and promoting the presentation of their biological activities. This review summarizes research progress on modified polysaccharides, including common chemical modification methods, the change in biological activity following modification, and the factors affecting the biological activity of chemically modified polysaccharides. At the same time, the difficulties and challenges associated with the structural modification of natural polysaccharides are also outlined in this review. Thus, research on polysaccharide structure modification is critical for improving the development and utilization of sugar products.

Mitigating drying shrinkage and enhancing mechanical strength of fly ash-based geopolymer paste with functionalized MWCNTs grafted with silane coupling agent

In this study, the functionalized MWCNTs grafted with silane coupling agent are obtained by means of successive chemical modification methods. The structure and dispersity of the functionalized MWCNTs are characterized using the FT-IR, XPS and HR-TEM, respectively. Then the reaction kinetics, mineralogical phases, morphology and elemental components of modified geopolymer incorporated with the functionalized MWCNTs are evaluated by means of the XRD, TAM, FT-IR and SEM-EDS analysis. In addition, the influences of functionalized MWCNTs on the mechanical strength and drying shrinkage behaviors are investigated. The MIP and 29Si NMR are employed to investigate the pore size distribution and microstructural rearrangement of gel products. The results show that the functionalized MWCNTs can be dispersed uniformly in aqueous solution without any dispersant. Importantly, the modified geopolymer incorporated with 0.2% functionalized MWCNTs-KH550 exhibits a lower drying shrinkage(0.098%) and higher mechanical strength compared with that of all geopolymer pastes. The hydrophobic modification of functionalized MWCNTs reduces significantly the mass loss of the geopolymer. The MIP results indicate that a critical pore size(ds)computed from both the pore size distributions and water loss is related with drying shrinkage, and the drying shrinkage of geopolymer pastes decreases with the increment of the ds value. A strong interaction between adjacent C(N)-A-S-H particles occurs in microstructure rearrangement period by means of the silicate polymerization and micropore closure. Moreover, the new dual interaction mechanism decreasing drying shrinkage and increasing mechanical strength of geopolymer pastes are proposed.

Ultrahigh Proton Conductivities of Postmodified Hf(IV) Metal-Organic Frameworks and Related Chitosan-Based Composite Membranes.

Recently, researchers have focused on preparing and studying proton exchange membranes. Metal-organic frameworks (MOFs) are candidates for composite membrane fillers due to their high crystallinity and structural characteristics, and Hf-based MOFs have attracted our attention with their high porosity and high stability. Therefore, in this study, Hf-based MOFs were doped into a cost-effective chitosan matrix as fillers to fabricate composite films having excellent proton conductivity (σ). First, the nanoscale MOFs Hf-UiO-66-(OH)2 (1) and Hf-UiO-66-NH2 (2) were chemically modified by a ligand design strategy to obtain SA-1 and CBD-2 bearing free -COOH units. The proton conductivities of SA-1 and CBD-2 under optimal test conditions reached 1.23 × 10-2 and 0.71 × 10-2 S cm-1. After that, we prepared composite membranes CS/SA-1 and CS/CBD-2 by the casting method; tests revealed that the introduction of MOFs improved the stabilities and σ values of the membranes, and their best σ could reach above 10-2 S cm-1 under 100 °C/98% RH. Further structural characterization and activation energy calculation revealed the conductive mechanism of the composite films. This investigation not only proposes a novel chemical modification method for optimizing the σ of MOFs but also promotes the development of MOF-doped composite membranes and provides a basis for future applications of MOFs in fuel cells.

Impact mechanism of methylation degree on structure and emulsifying ability of soy hull polysaccharides

As a chemical modification method, methylation may enhance the emulsification of polysaccharides. In this study, we methylated soy hull polysaccharide (SHP) at 60 °C for 0–8 h and analyzed the degree of methylation (DM), crystallinity, surface hydrophobicity, interfacial adsorption, and emulsification capacity of methylation-modified SHP (MSHP). Fourier infrared spectroscopy results showed that the DM changed from 41.48% ± 1.46%–58.30% ± 2.63% after 8 h of methylation (MSHP-8h). The polysaccharide residues were analyzed by 1H NMR. Increasing the DM improved the surface hydrophobicity of SHP, which effectively reduced the interfacial tension (IFT) of SHP at the O/W interface. At equilibration, the IFT was the lowest for MSHP-8h (15.40 mN/m). However, interface thickness was negatively correlated with the DM. Methylation promotes the migration of SHP to the oil side; therefore, the polysaccharide layer remaining in the aqueous phase decreases with an increasing DM at low and fixed SHP concentration. A reduction in hydrophilicity weakens the hydrogen bonds between polysaccharides to cause the polysaccharide layer to be easily destroyed during the dilution process of the droplet size measurement. However, thin adsorption or hydration layers can adversely affect the stability of the interfacial layer; consequently, emulsions prepared with MSHP-4h were the most stable. Our findings provide a practical and theoretical reference for improving emulsification ability of polysaccharides.

Tungsten Bronze-Type Ceramics for Temperature-Stable Energy Storage Properties: A Feasibility Study

The temperature-dependent energy storage properties of four tungsten bronze-type ceramics are studied together with an investigation of their structure and temperature-dependent permittivity response, i.e., Ba6Ti2Nb8O30 (BTN), Ba6Zr2Nb8O30 (BZN), Sr3TiNb4O15 (STN) and Sr3ZrNb4O15 (SZN) ceramics. With different cations at A and B sites, those four ceramics exhibit different crystal structures and show significantly different microstructure features and dielectric responses with changing temperatures. It was observed under SEM that BZN has smaller grains and a more porous structure than BTN. SZN shows the most porous structure among all samples, exhibiting a much lower permittivity response than other samples with no signs of phase transitions from room temperature to 400 °C. Though the energy storage response of those samples is generally quite low, they exhibit good temperature stability together with low dielectric loss. It was suggested that by obtaining a denser structure through chemical modification or other methods, those tungsten bronze ceramics with good temperature stability could be promising as energy storage devices when improved energy storage properties are achieved.

A Comprehensive Review of Pea (Pisum sativum L.): Chemical Composition, Processing, Health Benefits, and Food Applications.

Pisum sativum L., commonly referred to as dry, green, or field pea, is one of the most common legumes that is popular and economically important. Due to its richness in a variety of nutritional and bioactive ingredients, the consumption of pea has been suggested to be associated with a wide range of health benefits, and there has been increasing focus on its potential as a functional food. However, there have been limited literature reviews concerning the bioactive compounds, health-promoting effects, and potential applications of pea up to now. This review, therefore, summarizes the literature from the last ten years regarding the chemical composition, physicochemical properties, processing, health benefits, and potential applications of pea. Whole peas are rich in macronutrients, including proteins, starches, dietary fiber, and non-starch polysaccharides. In addition, polyphenols, especially flavonoids and phenolic acids, are important bioactive ingredients that are mainly distributed in the pea coats. Anti-nutritional factors, such as phytic acid, lectin, and trypsin inhibitors, may hinder nutrient absorption. Whole pea seeds can be processed by different techniques such as drying, milling, soaking, and cooking to improve their functional properties. In addition, physicochemical and functional properties of pea starches and pea proteins can be improved by chemical, physical, enzymatic, and combined modification methods. Owing to the multiple bioactive ingredients in peas, the pea and its products exhibit various health benefits, such as antioxidant, anti-inflammatory, antimicrobial, anti-renal fibrosis, and regulation of metabolic syndrome effects. Peas have been processed into various products such as pea beverages, germinated pea products, pea flour-incorporated products, pea-based meat alternatives, and encapsulation and packing materials. Furthermore, recommendations are also provided on how to better utilize peas to promote their development as a sustainable and functional grain. Pea and its components can be further developed into more valuable and nutritious products.

Chemical Modification of Peptides and Proteins Using Spirooxindole Oxirane Derivatives

AbstractMethods for chemical modification of proteins and peptides at certain positions are required for the preparation of antibody‐drug conjugates, protein‐ or peptide‐biotin conjugates, and conjugates used as therapeutics or as tools in biomedical research. We have developed chemical modification methods that use spirooxindole oxirane derivatives for the synthesis of protein‐ and peptide‐conjugates. In most cases, the epoxide group of the spirooxindole oxirane derivatives reacted to form a covalent bond with certain histidine residues and/or the N‐terminal amino group of peptides and proteins. The modification reactions of various proteins resulted in the formation of proteins modified at only one or two positions.