Non-covalent Modification Research Articles

Enhancing soy protein isolate flexibility through non-covalent ferulic acid modification: implications for interfacial characteristics and protein-based emulsion performance

This study aims to enhance the flexibility of soy protein isolate (SPI) to improve its functional properties, focusing on the investigated the effects of ferulic acid (FA) on the structure, interfacial behaviour and emulsification performance of SPI. Our study showed that FA induces SPI structures to depolymerization and unfolding primarily through hydrogen bonding and hydrophobic interactions, thereby increasing the flexible structures (random coils and β-turns) of protein. These changes enhanced the interfacial functional properties of SPI, with 150 μmol/g of FA-modified SPI exhibiting the best molecular flexibility, and its emulsification and emulsification stability were improved by 21.26% and 39.86%, respectively, compared to unmodified SPI. In addition, non-covalently modified FA significantly improved emulsions stability. Emulsions stabilized by SPI-FA150 complexes exhibited better storage, heat, and freeze-thaw stability than SPI, with a significant reduction in oxidation products. This relationship between flexibility and function reveals the importance of structural modification in enhancing protein functionality. These discoveries shed new light on flexible protein processing technologies and the application of FA in protein functional modification.

Functionalization of boron nitride with poly(catechol-polyamine) and bis(γ-triethoxysilylpropyl)tetrasulfide for preparing epoxy nanocomposites with enhanced thermal conductivity

Hexagonal boron nitride (hBN) has garnered significant interest as inorganic thermally conductive material in electronic packaging due to its high-efficiency thermal management capability and electrical insulation properties. However, the relatively inert chemical environment of the BN surface hinders phonon transfer at the interface. Additionally, the high content of inorganic components in the matrix leads to the deterioration of the composite’s mechanical properties. In this research, h-BN surface is modified using poly(catechol-polyamine) (PCPA) and bis (γ-triethoxysi-lylpropyl)tetrasulphide (Si69) (denoted as BN-PCPA-Si69). The noncovalent PCPA modification protects the endothermic properties of BN, Si69 provides covalent bonding between thermally conductive fillers and bisphenol A-type epoxy resin (Ep), and the interfacial compatibility between BN and epoxy resin is improved. The heat conductivity of final BN/Ep composite achieved 0.817 W/(m·K) containing 30 wt% BN. Correspondingly, the heat conductivity of the composite (mBN/Ep) achieved 0.881 W/(m·K) containing 30 wt% BN-PCPA-Si69. Compared to pure epoxy resin (0.200 W/(m·K), the thermal conductivity (TC) of the mBN/Ep composite increased by 364% while maintaining good electrical insulation properties. The proposed BN surface functionalization approach has potential applications in fields such as microelectronic packaging, where materials need to balance high thermal conductivity and electrical insulation.

Fabrication of PVC-based electromagnetic interference shielding composite film by positively charged SMA enhancing the dispersibility of carbon nanomaterial

To address the weak binding force and poor dispersion stability of carbon (C) nanoparticles in current non-covalent modification methods, we employed organic amine-grafted styrene maleic anhydride copolymers (SMA-N) to modify C nanoparticles (C@SMA-N) through π–π conjugation and positive charge interactions. The obtained C@SMA-N has excellent dispersion in N, N-dimethylacetamide (DMAc), which is attributed to the enhanced steric hindrance and electrostatic repulsion from the grafted organic amine chains. To study the impact of surface modification on the electromagnetic interference shielding effectiveness (EMI SE), C@SMA-N was used as a conductive filler in polyvinyl chloride (PVC) composite films, which exhibits a higher EMI SE performance than pristine C nanoparticles. Particularly, the obtained C@SMA-N using polyether amine (PEA) (C@SMA-PEA) exhibits a better EMI SE performance. By optimizing the SMA-PEA grafting parameters, the PVC/C@SMA-PEA composite films transition from insulators to conductors at a C@SMA-PEA content of 0.3 wt%. To achieve a higher EMI SE performance, the filler content, mixed filler composition, and film thickness were optimized. The results indicate that with a total filler content of 20 wt% and a mixed filler comprising fibrous form carbon nanotubes (CNT) and particles form carbon black (CB) in a 10:1 mass ratio (CB@SMA-PEA to CNT@SMA-PEA), the composite film has a thickness of 0.08 mm and an EMI SE value of 20.2 dB. Increasing the thickness to 0.2 mm enhances the EMI SE value to 31.5 dB. These findings indicate that thinner films have a higher EMI SE performance and promising application prospects in the field of electromagnetic shielding.

Study on Thermally Induced Lignin Aggregation Kinetics for the Preparation of Uniformly Sized Lignin Nanoparticles in Water.

Lignin nanoparticles (LNPs) present a potential avenue for the high-value utilization of lignin. However, the simple and ecofriendly method of thermally induced self-assembly for the preparation of LNPs has been overlooked due to a lack of sufficient understanding of the lignin aggregation mechanism. Therefore, this study focuses on the kinetics of thermally induced lignin aggregation. It was found that lignin aggregates formed at lower temperatures exhibit poor stability and are more prone to continuous growth through coalescence. This apparent contradiction with the conventional understanding of thermoresponsive polymers could be attributed to changes in the viscoelasticity of the lignin aggregates during phase separation. Based on this finding, we worked out strategies to optimize the preparation of LNPs in water through thermally induced self-assembly. Pure LNPs with well-defined interfaces and a minimum polydispersity index (PDI) of 0.12 were obtained by increasing the temperature to 125-150 °C. Furthermore, combined with noncovalent modification, LNPs with a PDI of 0.08 would even be formed at 80 °C. Notably, the resulting pure LNPs show potential for application in photonic crystal products that require excellent monodispersity. This study provides a new approach for the environmentally friendly preparation of LNPs with a controllable morphology.

Effect of mechanochemistry on graphene dispersion and its application in improving the mechanical properties of engineered cementitious composites

To improve the dispersibility of graphene in cement-based materials and achieve better mechanical properties, this study proposes a novel and practical mechanochemical grafting strategy through ball milling technique. The polycarboxylate-based superplasticizer was successfully grafted on graphene, inducing both covalent and non-covalent modifications of the graphene surface simultaneously. The mechanochemistry method under different conditions, e.g., dry milling or wet milling, was investigated. The dispersion efficiency of prefabricated graphene was compared with traditional ultrasonic dispersion methods. The graphene prepared with these dispersion methods was then applied to prepare Engineered Cementitious Composites (ECC). The results indicated that the proposed mechanochemical methods can effectively reduce particle size, increase specific surface area, and introduce abundant functional groups, thereby improving the dispersibility of graphene. Especially under wet milling conditions, smaller and more dispersed particles could be produced. The addition of well dispersed graphene at 0.1 wt% in engineered cementitious composites (ECC) showed a 24.0 % increase in compressive strength, a 32.4 % increase in tensile strength, and a 66.9 % increase in ultimate tensile strain. This improvement is attributed to the a capability of graphene sheets processed by ball milling to impede the propagation of cracks within the cement matrix.

Back on the chain gang: polyphosphate modification of proteins

Polyphosphate (polyP) mediates a plethora of biological functions. Understanding the polyP-protein interactome will help clarify the mechanisms underpinning these functions. Recent studies demonstrating a strong but noncovalent modification of lysine and histidine repeat proteins by polyP have provided new insights into polyP-protein biochemistry with implications for research and therapeutics.

Self-assembly and functional activity of amphiphilic conjugates of the diterpenoid isosteviol and triphenylphosphonium cation, with focusing on biotechnological potential

Supramolecular systems based on amphiphilic triphenylphosphonium (TPP) conjugates of the diterpenoid isosteviol in which the diterpenoid skeleton and the TPP cation are linked by a polymethylene linker of varying length (n = 3, 6 or 8) have been fabricated. Elongation of this linker from 3 to 8 methylene units, allows for an 8-fold decrease in the amphiphile aggregation thresholds in aqueous solutions. These systems exhibit tunable self-assembly behavior, with the formation of both small aggregates (with a hydrodynamic diameter of ∼5–10 nm), as well as large vesicle-like structures (with a diameter of ∼50–100 nm), depending on the amphiphile concentration and length of the spacer fragment. The biotechnological potential of these amphiphiles has been demonstrated on the example of its membranotropic properties toward liposomes consisting of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Significant capacity for integration into lipid bilayer has been revealed in these amphiphiles, which could be increased by extending the length of the polymethylene linker. Cationic liposome formulations have been prepared on the basis of these amphiphiles and DPPC by a noncovalent modification approach. Sustainability of its DH and zeta potential during longtime storage has been demonstrated. The studied systems exhibit a selective cytotoxic effect on M-HeLa cancer cell line and are a less toxic to normal Chang liver cells. The mechanism of the cytotoxic action of the liposomes is associated with the induction of apoptosis through mitochondrial pathway. The obtained formulations have successfully been applied for metronidazole encapsulation, characterized by high encapsulation efficiency and loading capacity, as well as prolonged time of drug release.

In situ monitoring of polymeric patchy micelles upon non-covalent post-assembly modification

ABSTRACT Polymeric patchy micelles (PPMs) are nanostructures with distinct regions on their surfaces, offering unique properties for various applications. Herein, we present a straightforward method for monitoring the structure of PPMs formed via non-covalent post-assembly modification (NCPAM). By employing 1-pyrenemethylamine, a pyrene-based molecule, as both a modifier and fluorescent probe, we demonstrate that the formation of PPMs with a higher order aggregation state of pyrene induces a stronger pyrene excimer emission. This leads to variations in the excimer-to-monomer emission ratio, serving as a parameter for studying structural changes in PPMs during NCPAM. In situ monitoring of PPM formation and temperature-dependent transformations is achieved using fluorescent analytical method, providing valuable insights into their structural evolution and dynamic behaviour. This study offers a straightforward approach to understanding and controlling PPM structures, facilitating the design of advanced nanomaterials for diverse applications.

From Collagen Mimetics to Collagen Hybridization and Back.

ConspectusFacilitated by the unique triple-helical protein structure, fibrous collagens, the principal proteins in animals, demonstrate a dual function of serving as building blocks for tissue scaffolds and as a bioactive material capable of swift renewal in response to environmental changes. While studies of triple-helical collagen mimetic peptides (CMPs) have been instrumental in understanding the molecular forces responsible for the folding and assembly of triple helices, as well as identifying bioactive regions of fibrous collagen molecules, single-strand CMPs that can specifically target and hybridize to denatured collagens (i.e., collagen hybridizing peptides, CHPs) have proven useful in identifying the remodeling activity of collagen-rich tissues related to development, homeostasis, and pathology. Efforts to improve the utility of CHPs have resulted in the development of new skeletal structures, such as dimeric and cyclic CHPs, as well as the incorporation of artificial amino acids, including fluorinated proline and N-substituted glycines (peptoid residues). In particular, dimeric CHPs were used to capture collagen fragments from biological fluid for biomarker study, and the introduction of peptoid-based collagen mimetics has sparked renewed interest in peptidomimetic research because peptoids enable a stable triple-helical structure and the presentation of an extensive array of side chain structures offering a versatile platform for the development of new collagen mimetics.This Account will cover the evolution of our research from CMPs as biomaterials to ongoing efforts in developing triple-helical peptides with practical theranostic potential in targeting denatured and damaged collagens. Our early efforts in functionalizing natural collagen scaffolds via noncovalent modifications led to the discovery of an entirely new use of CMPs. This discovery resulted in the development of CHPs that are now used by many different laboratories for the investigation of pathologies associated with changes in the structures of extracellular matrices including fibrosis, cancer, and mechanical damage to collagen-rich, load-bearing tissues. Here, we delve into the essential design features of CHPs contributing to their collagen binding properties and practical usage and explore the necessity for further mechanistic understanding of not only the binding processes (e.g., binding domain and stoichiometry of the hybridized complex) but also the biology of collagen degradation, from proteolytic digestion of fibrils to cellular processing of collagen fragments. We also discuss the strengths and weaknesses of peptoid-based triple-helical peptides as applied to collagen hybridization touching on thermodynamic and kinetic aspects of triple-helical folding. Finally, we highlight current limitations and future directions in the use of peptoid building blocks to develop bioactive collagen mimetics as new functional biomaterials.

The multiple faces of graphene on anticorrosion: Advances and prospects

In recent years, graphene has remarkably enhanced the protective performance of anticorrosive organic coatings, yielding increasingly frequent exciting results and perspectives. This paper reviews the latest research advancements that we have gathered on the influences of conductivity, modification, dispersion methods and controllable orientation of graphene; the graphene-based smart anticorrosive coatings; the current understandings on the designs of the anticorrosive coating and the action mechanisms of graphene in the coating. It is concluded that there would be greater opportunities for the gravitational field-induced method to play the shielding effect of graphene; noncovalent modification methods may not ensure satisfactory attachment of the modifiers to the surface; green modification methods are expected to reduce the electrical conductivity of graphene and covalently modify graphene; the self-healing and early-warning graphene-based anticorrosive coatings are becoming a trend in the development of anti-corrosive coatings. The current-faced challenges and the future development prospects of the graphene-based anticorrosive coating were also proposed. Although graphene performs well in anticorrosive coatings, there is still considerable room to improve the performance, and a new round of industrial optimisation and upgrading in the anti-corrosion coating industry is inevitable with the rapid development of the anticorrosive graphene-based filler.

Polyphosphate attachment to lysine repeats is a non-covalent protein modification

Polyphosphate (polyP) is a chain of inorganic phosphate that is present in all domains of life and affects diverse cellular phenomena, ranging from blood clotting to cancer. A study by Azevedo etal. described a protein modification whereby polyP is attached to lysine residues within polyacidic serine and lysine (PASK) motifs via what the authors claimed to be covalent phosphoramidate bonding. This was based largely on the remarkable ability of the modification to survive extreme denaturing conditions. Our study demonstrates that lysine polyphosphorylation is non-covalent, based on its sensitivity to ionic strength and lysine protonation and absence of phosphoramidate bond formation, as analyzed via 31P NMR. Ionic interaction with lysine residues alone is sufficient for polyP modification, and we present a new list of non-PASK lysine repeat proteins that undergo polyP modification. This work clarifies the biochemistry of polyP-lysine modification, with important implications for both studying and modulating this phenomenon. This Matters Arising paper is in response to Azevedo etal. (2015), published in Molecular Cell. See also the Matters Arising Response by Azevedo etal. (2024), published in this issue.

Functionalization of Carbon Nanotubes in Polystyrene and Properties of Their Composites: A Review.

The inherent π-π interfacial interaction between carbon nanotubes (CNTs) and polystyrene (PS) makes the CNT/PS composite a representative thermoplastic nanocomposite. However, the strong van der Waals force among CNTs poses challenges to achieving effective dispersion. This review provides an overview of various CNT functionalization methods for CNT/PS composites, encompassing covalent grafting with PS-related polymers and non-covalent modification. A focus in this section involves the pre-introduction surface modification of CNTs with PS or PS-related polymers, substantially enhancing both CNT dispersibility and interfacial compatibility within the PS matrix. Furthermore, a comprehensive summary of the mechanical, electrical, thermal, and electromagnetic shielding properties of CNT/PS nanocomposites is provided, offering an overall understanding of this material. The surface modification methods of CNTs reviewed in this paper can be extended to carbon material/aromatic polymer composites, assisting researchers in customizing the optimal surface modification methods for CNTs, maximizing their dispersibility, and fully unleashing the various properties of CNTs/polymer composites. Additionally, high-performance CNTs/PS composites prepared using appropriate CNT modification methods have potential applications in areas such as electronic devices, sensors, and energy storage and conversion.

Synthesis of alkynyl spacer-containing chiral polyguanidines and their noncovalent modification for organocatalyst design

A novel biscarbodiimide compound containing alkynyl spacer has been prepared and successfully used as an electrophilic comonomer in the polyaddition reaction with chiral secondary and primary 1,2-diamines. The resulting chiral polyguanidines have exhibited Brønsted base catalytic activities with asymmetric induction ability, which can be greatly enhanced through noncovalent modification with achiral Brønsted acids, such as phosphoric acid diesters and carboxylic acids. This study reveals for the first time the validity of a strategy incorporating guanidine functionality into polymer main chains followed by their noncovalent modification for organocatalyst design.

Silicone and nano-diamond modified graphene oxide anticorrosive coating

Graphene oxide (GO) has abundant oxygen-containing functional groups, making it easy to undergo covalent and non-covalent modifications, coupled with its excellent physical barrier ability, which shows great prospects in improving the corrosion resistance of coatings. Unfortunately, GO has a strong van der Waals force and π-π interactions, which make it prone to self-aggregation, and at the same time, in the process of preparing the coating due to the volatilization of solvents, it is easy to produce micropores and other defects, which will not be conducive to the long-term corrosion resistance of the coating. Therefore, this work used silicone as a “bridge” to modify GO with nanodiamond, and then a composite coating with excellent anticorrosion properties was prepared with vinyl ester resin under heating conditions. This work not only effectively solved the dispersion and interface interaction of GO in the resin, but also the diluent in this process could fully participate in the polymerization reaction, effectively avoiding the volatilization of volatile gases. The results showed that the conductivity of the modified GO reached the level of the insulating material (9.6 × 10−9 S/cm, 30 MPa pressure). Electrochemical tests showed that the |Z|0.01Hz value of the coating was as high as 1.00 × 109 Ω cm2 after soaking in 3.5 wt% brine for 120 days, which was three orders of magnitude higher than the control group. Compared to the control group, the protective efficiency of the coating remained at 97.8 %. This was mainly related to the synergistic anticorrosion effect of GO and nano-diamond. In short, this work provided a new research approach for the preparation of long-lasting anticorrosion coatings using zero-dimensional and two-dimensional materials.

Egg White Protein-Proanthocyanin Complexes Stabilized Emulsions: Investigation of Physical Stability, Digestion Kinetics, and Free Fatty Acid Release Dynamics.

Egg white proteins pose notable limitations in emulsion applications due to their inadequate wettability and interfacial instability. Polyphenol-driven alterations in proteins serve as an effective strategy for optimizing their properties. Herein, covalent and non-covalent complexes of egg white proteins-proanthocyanins were synthesized. The analysis of structural alterations, amino acid side chains and wettability was performed. The superior wettability (80.00° ± 2.23°) and rigid structure (2.95 GPa) of covalent complexes established favorable conditions for their utilization in emulsions. Furthermore, stability evaluation, digestion kinetics, free fatty acid (FFA) release kinetics, and correlation analysis were explored to unravel the impact of covalent and non-covalent modification on emulsion stability, dynamic digestion process, and interlinkages. Emulsion stabilized by covalent complex exhibited exceptional stabilization properties, and FFA release kinetics followed both first-order and Korsmeyer-Peppas models. This study offers valuable insights into the application of complexes of proteins-polyphenols in emulsion systems and introduces an innovative approach for analyzing the dynamics of the emulsion digestion process.

Targeting and Microenvironment-Activated Nanoreactor for Diabetic Chronic Wound Healing via Multienzyme Cascade Reactions.

The development of cell-like nanoreactors with the ability to initiate biocatalytic cascades under special conditions holds tremendous potential for therapeutic applications. Herein, conformationally gated nanoreactors that respond to the acidic microenvironment of infected diabetic wounds were developed by cucur[8]bituril (CB[8])-based supramolecular assembly. The bioinspired nanoreactors exhibit not only self-regulated permeability and selectivity to control internal enzyme activities by substance exchange but also distinct binding specificities toward Gram-positive and Gram-negative bacteria via noncovalent modification with different ligands. The encapsulation of glucose oxidase (GOx), Fe3O4 nanozyme, and l-arginine (l-Arg) into the nanocarriers enables intelligent activation of multienzyme cascade reactions upon glucose (Glu) uptake to produce gluconic acid (GA) and hydrogen peroxide (H2O2), which is further converted into highly toxic hydroxyl radicals (·OH) for selective antibacterial activity. Moreover, acidic H2O2 promotes the oxidization of l-Arg, leading to the release of nitric oxide (NO). Consequently, this nanoreactor provides a multifunctional and synergistic platform for diabetic chronic wound healing by combining enzyme dynamic therapy with NO gas therapy to combat bacterial infections and inflammation under high blood Glu levels.

Review of: "Covalent and non-covalent modifications are two general methods for coupling biological molecules and CP nanomaterials"

Review of: "Covalent and non-covalent modifications are two general methods for coupling biological molecules and CP nanomaterials"

Review of: "Covalent and non-covalent modifications are two general methods for coupling biological molecules and CP nanomaterials"

Review of: "Covalent and non-covalent modifications are two general methods for coupling biological molecules and CP nanomaterials"

Noncovalent Conjugation of OVA323 to ELP Micelles Increases Immune Response.

Subunit vaccines would benefit from a safe particle-based adjuvant. Elastin-like polypeptide (ELP)-based micelles are interesting candidate adjuvants due to their well-defined size and easy modification with protein-based cargo. Coiled coils can facilitate noncovalent modifications, while potentially enhancing antigen delivery through interaction with cell membranes. ELP micelles comprise ELP diblock copolymers that self-assemble above a critical micelle temperature. In this study, an amphiphilic ELP was conjugated to peptide "K", which forms a heterodimeric coiled-coil complex with peptide "E". Self-assembled "covalent" micelles containing ELP-OVA323 (i.e., model antigen OVA323 conjugated to ELP), "coiled-coil" micelles containing ELP-K/E-OVA323 and "hybrid" micelles containing ELP-K and ELP-OVA323 were shown to be monodisperse and spherical. Dendritic cells (DCs) were exposed to all micelle compositions, and T-cell proliferation was investigated. The presence of ELP-K enhanced micelle uptake and subsequent DC maturation, resulting in enhanced CD4+ T-cell proliferation, which makes ELPs with coiled coil-associated antigens a promising vaccine platform.

Cell-penetrating peptides noncovalently modified red phosphorescent nanoparticles for high-efficiency imaging.

The application of long-lived phosphorescence probes in time-resolved luminescence imaging is limited by their low quantum yield in aqueous solutions. However, sensitization of thermally activated delayed fluorescence (TADF) materials can compensate for this limitation while addressing the issue of insufficient proportion of their own long lifetime. In this study, we utilized the characteristics of phosphorescence and TADF materials simultaneously by doping the receptor iridium complex PMD-Ir into the donor TADF polymer PCzDP-20 through donor-receptor doping method, and successfully prepared highly efficient red phosphorescent nanoparticles. The quantum yield of the nanoparticles obtained by this method reaches up to 30%, and the luminescence lifetime can reach several thousand nanoseconds. Additionally, due to the low concentration doping of PMD-Ir, the risk of transition metal toxicity is greatly reduced. Furthermore, we used non-covalent modification with amphiphilic cell-penetrating peptides (CPPs) to increase the cell membrane permeability of the nanoparticles. The CPPs modified nanoparticles achieve in vivo confocal imaging of zebrafish and intracellular time-resolved imaging by its significantly improved bioimaging capabilities. The functional nanoparticles designing method fully utilizes the characteristics of PMD-Ir, PCzDP-20, and CPPs, solving the problems of low quantum yield and poor membrane permeability of Ir-complex nanoparticles. This will greatly promote the development of time-resolved luminescence imaging.