Molecular Modification Research Articles

Exploring the Metal-Insulator Transition in (Ga,Mn)As by Molecular Absorption.

The metal-insulator transition (MIT) is normally assisted by certain external power input, such as temperature, pressure, strain, or doping. However, these may increase the disorder of the crystal or cause other effects, which makes device fabrication complicated and/or hinders large-scale application. Here, we adopt a new approach to obtain robust modulation of physical properties in magnetic semiconductor (Ga,Mn)As by surface molecular modification. We have probed both sides of the MIT with n- and p-type molecular doping. Density functional theory calculations are carried out to determine the stable absorption configuration and charge transfer mechanism of electron acceptor and donor molecules on the semiconductor surface. Both experimental and theoretical results confirm a remarkable modulation in carrier concentrations without introducing impurities or defects. This work points out the possibility of effectively tuning physical properties of solid-state materials by functional molecules, which is clean, flexible, nondestructive, and easily achieved.

Combined Atomic and Molecular Layer Deposition Surface Modification of Carbon Nanotubes for CNT–Epoxy Polymer Composites

Optimizing the interactions between the matrix and reinforcement components is key to attaining high-performance composite materials. Yet, balancing the reinforcing–matrix phase interactions for synthetic composites remains a great challenge. Here, a combined methodology using molecular and atomic layer deposition (M/ALD) is demonstrated for tailoring carbon nanotube (CNT) interfacial interactions, yielding high-performance-reinforced polymer composites. CNT mats are used as a model system to systematically study the molecular details as they do not involve powder processing and other aspects which obscure the understanding of molecular level effects. Noncovalent attachment of the M/ALD layer at the interface allows good wetting of the CNTs, provides an effective means for stress dissipation without compromising the CNTs’ Csp2–Csp2 network which remains intact, while introducing amine functionalities to facilitate the cross-linking polymer matrix (epoxy). M/ALD-modified CNT mat–epoxy composites showed an increase in the maximal tensile strength and toughness of up to 32 and 247%, respectively. These findings may pave the way to systematically develop high CNT loading composites as well as other nano-reinforced composite systems showing both high strength and toughness as well as numerous other desirable properties related to nanomaterial composites in general.

Space-selective creation of photonics functions in a new organic material: Femtosecond laser direct writing in Zeonex glass of refractive index change and photoluminescence

A Cyclo Olefin Polymer (COP), Zeonex® glass exhibits advantage for applications in photonics: high transparency from NIR to UVA, humidity insensitivity and refractive index stability. We thus studied this organic glass, made with only carbon and hydrogen to show that it can be used as a substrate for photonics. We investigated the microscale transformations induced by fs laser direct writing according to parameters: pulse energy, repetition rate, scanning speed (or time of irradiation). We pointed out two domains of modifications, one at low mean power between 0.1 and 20 mW and another above 20 mW. We called them type I and II. In type I, two basic modifications – photoluminescence (PL) creation are restricted to the irradiated volume at the scale of beam size, a large refractive index change (+0.14) appears when the pulse repetition rate is high(>500 kHz), enabling local modulation of optical properties for potential applications. Here, modification of the COP molecule is moderate and the spatial sensitivity is of the order of μm. In type II, the modification is more extended but PL is much stronger. Through correlations between the PL results, we defined signatures composed of luminophore series: S1 associated to type I, S2 associated to type II and S3 for intermediate conditions. S1 is the luminescent group, with the largest yield excitable at 475 nm with a broad emission from green to orange-yellow. S2 is remarkable with a broad excitation in the green and broad emission in yellow range. S1 and S3 results from small molecular modification but S2 is likely resulting from the disruption of COP molecule forming Carbon Dots.

N -Heterocycles Extended π-Conjugation Enables Ultrahigh Capacity, Long-Lived, and Fast-Charging Organic Cathodes for Aqueous Zinc Batteries

<i>N</i> -Heterocycles Extended π-Conjugation Enables Ultrahigh Capacity, Long-Lived, and Fast-Charging Organic Cathodes for Aqueous Zinc Batteries

Microbial elimination of pyrethroids: specific strains and involved enzymes.

Pyrethroids, which are synthetic organic insecticides, are widely used in agriculture and households to resist pests and control disease transmission. However, pyrethroids have inevitably caused environmental pollution, leading to concerns for food safety and human health. Bioremediation has emerged as one of the most promising methods to eliminate pyrethroids compounds. Pyrethroid-degrading microorganisms and the relevant enzymes have shown an efficient ability in degrading pyrethroids by hydrolyzing the ester linkage. In this review, a wide variety of pyrethroid-degrading strains were presented and classified from different sources, such as wastewater, soils, and oceans. In addition, the recombinant expression, enzyme identification, and molecular modification of these microbial pyrethroid-degrading enzymes were also compared and discussed in detail. Moreover, the potential applications of pyrethroid-degrading enzymes, including immobilization and biodegradation towards a series of pyrethroids, were also presented. All of the positive results obtained from this review could be a good guideline for the other research in this field. KEY POINTS: • Distribution of pyrethroid-degrading strains in different sources was summarized. • Enzymatic properties including pH, temperature, and substrate specificity were compared. • Promising molecular modification and immobilization of hydrolases were present.

A new approach to replace antibiotics with natural pigment derivatives: Surface modification on the titanium implants

Bacterial infections associated with metal implants and devices are an urgent challenge in biomedical materials, especially when bacterial biofilms form on the implant surface. Here, we developed a novel strategy to combat infections with bacteria-associated titanium implants. Curcumin molecular modification was carried out on the phenolic hydroxyl group to obtain curcumin carboxylic acid (Cur-COOH) with the β-diketone structure of curcumin retained. Cur-COOH was covalently immobilized on the (3-aminopropyl) triethoxysilane (APTES)-treated titanium surface via an amidation reaction to establish the curcumin-titanium implant interface (Ti-g-Cur). Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), water contact angle (WCA), and X-ray photoelectron spectroscopy (XPS) proved that Cur-COOH was successfully anchored on the titanium implants surface. Ti-g-Cur showed excellent antibacterial activity against E. coli and S. aureus, with antibacterial rates of 90.53 % and 94.38 %, respectively. Confocal laser scanning microscopy (CLSM) imaging showed that Ti-g-Cur could effectively inhibit bacterial biofilm formation for up to 5 days. In addition, Ti-g-Cur exhibited superior performance on mammalian hemocompatibility and cytocompatibility. Replacing antibiotics with natural pigment curcumin derivatives for application in biological materials can not only result in a high degree of biocompatibility but also fights bacteria and biofilm formation effectively.

BiVO4 photoanode modification by synergic dual-conjugated organic materials

Organic conjugated materials have presented considerable application potential in the field of photoelectrochemical (PEC) water splitting. In this study, two organic conjugated materials, two dimension carbon nitride (2D-C 3 N 4 ) and organic cobalt molecular catalyst ((H 3 O) 6 ·[Co 4 (H 2 O) 4 (HPMIDA) 2 (PMIDA) 2 )]·2H 2 O) (OCM), are fabricated in turn on the surface of bismuth vanadate (BVO) photoanode. Basing on the synergistic effect of 2D-C 3 N 4 and OCM, the PEC property of the modified BVO photoanode increases three times higher than that of bare BVO photoanode at 1.23 V vs. RHE by increasing reaction active surface, promoting charge separation, and reducing reaction overpotential. This study shows that organic conjugated materials can not only form an effective heterojunction system with semiconductor materials and improve surface catalytic activity, but also assemble easily by the strong affinity between g-C 3 N 4 and OCM. Therefore, it provides a novel and efficient modification method by dual-conjugated organic materials to improve the PEC performance of photoelectrodes. • Development of 2D-C 3 N 4 /organic cobalt molecular dual-conjugated water oxidation catalyst. • 2D-C 3 N 4 /organic cobalt molecular catalyst modified BiVO 4 photoanode was prepared by first time. • A synergistic effect was found between conjugated 2D-C 3 N 4 and organic cobalt molecular. • A photocurrent density of BiVO 4 photoanode increased three times after dual-conjugated molecular modification.

Zearalenone lactonase: characteristics, modification, and application.

Zearalenone (ZEN) and its derivatives are one of the most contaminated fungal toxins worldwide, posing a severe threat to food security and human life. Traditional physical and chemical detoxifying methods are unsatisfactory due to incomplete detoxification, nutrient loss, and secondary pollutants. In recent years, bioremediation for eliminating fungal toxins has been gradually investigated. ZEN lactone hydrolase (lactonase) has been widely studied because of its high activity, mild conditions, and non-toxic product property. This review comprehensively represents the gene mining, characterization, molecular modification, and application of microbial-derived ZEN lactonases. It is aimed to elucidate the advantages and challenges of ZEN lactonases in industrial application, which also provides perspectives on obtaining innovative and promising biocatalysts for ZEN degradation. KEY POINTS: • A timely and concise review related to enzymatic elimination towards ZEN is shown. • The catalytic conditions and mechanism of ZEN lactonase is presented. • The modification and application of ZEN lactonase are exhibited also.

Molecular structural modification of β-conglycinin using pH-shifting with ultrasound to improve emulsifying properties and stability

This present work underlines the effect of pH-shifting at pH 2 and pH 12 individually or combined with ultrasound treatment to modify the molecular structure of β-conglycinin (7S) on its emulsifying properties and stability. Fourier transform infrared (FTIR) spectroscopy and intrinsic fluorescence spectroscopy showed that pH-shifting improves the molecular structure of 7S, while ultrasound further promotes structural changes. In particular, the pH-shifting at pH 12 combined with ultrasound treatment (U-7S-12) resulted in more significant changes than the pH-shifting at pH 2 combined with ultrasound (U-7S-2). U-7S-12 showed a significant reduction in protein particle size from 152 to 34.77 nm and a relatively smooth protein surface compared to 7S. The protein had the highest surface hydrophobicity and flexibility at 81,560.0 and 0.45, respectively, and the free sulfhydryl content from 1.57 to 2.02 μmol/g. In addition, we characterized the emulsions prepared after 7S treatment. The single or combined treatment increased the interfacial protein adsorption of the samples, which showed lower viscosity and shear stress compared to 7S. The U-7S-12 emulsion exhibited the highest emulsifying properties and was more stable than other emulsions under creaming, heating, and freeze–thaw conditions. In summary, the concerted action of pH-shifting and ultrasound can modify the structure, and combined alkaline pH-shifting and ultrasound treatment can further improve the emulsifying properties and stability of 7S.

Improving catalytic activity of Lactobacillus harbinensis d-mandelate dehydrogenase toward d-o-chloromandelic acid by laboratory evolution

In the pharmaceutical and chemical industry, l-o-chlorophenylglycine and its derivatives are very important building blocks. Nevertheless, the catalytic activity of natural d-mandelate dehydrogenase (DMDH) toward d-o-chloromandelic acid (D-o-CMA) was very low, which greatly limits its industrial application. Taking Lactobacillus harbinensisd-mandelate dehydrogenase (LhDMDH) as parent, laboratory evolution was performed to improve its catalytic performance toward d-o-chloromandelic acid. An A59G/N252G mutant of LhDMDH with a higher catalytic performance toward d-o-chloromandelic acid was obtained, its catalytic activity was approximately 8.4 times than that of LhDMDH. Furthermore, the optimal reaction temperature of A59G/N252G is 50 °C. Meanwhile, the Kcat value toward d-o-CMA of A59G/N252G is 18.33 s − 1, which is about 10 times of LhDMDH (1.81 s − 1). Lastly, using the in silico design approach, the molecular basis about its catalytic performance improvement was preliminarily explored. Therefore, these researchs established solid practice foundation for the molecular modification of d-mandelate dehydrogenase for catalytic performance.

Design, Synthesis, and Study of a Novel RXPA380-Proline Hybrid (RXPA380-P) as an Antihypertensive Agent.

In drug discovery, molecular modification over the lead molecule is often crucial for the development of a drug. Herein, we report the molecular hybridization design of a novel RXPA380–proline hybrid via linking the parent compound, phosphinic peptide RXPA380, with a proline analogue. The presented synthetic route is straightforward and produces the desired product RXPA380-P in moderate yield. The C- and N-domain constructs of the angiotensin-converting enzyme of RXPA380-P appeared to be poor inhibitors of ACE as compared to the parent compound RXPA380.

Role of Molecular Modification and Protein Folding in the Nucleation and Growth of Protein-Metal-Organic Frameworks.

Metal–organic frameworks (MOFs) are a class of porous nanomaterials that have been extensively studied as enzyme immobilization substrates. During in situ immobilization, MOF nucleation is driven by biomolecules with low isoelectric points. Investigation of how biomolecules control MOF self-assembly mechanisms on the molecular level is key to designing nanomaterials with desired physical and chemical properties. Here, we demonstrate how molecular modifications of bovine serum albumin (BSA) with fluorescein isothiocyanate (FITC) can affect MOF crystal size, morphology, and encapsulation efficiency. Final crystal properties are characterized using scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), fluorescent microscopy, and fluorescence spectroscopy. To probe MOF self-assembly, in situ experiments were performed using cryogenic transmission electron microscopy (cryo-TEM) and X-ray diffraction (XRD). Biophysical characterization of BSA and FITC-BSA was performed using ζ potential, mass spectrometry, circular dichroism studies, fluorescence spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The combined data reveal that protein folding and stability within amorphous precursors are contributing factors in the rate, extent, and mechanism of crystallization. Thus, our results suggest molecular modifications as promising methods for fine-tuning protein@MOFs’ nucleation and growth.

Embedding Thiophene-Amide into g-C3N4 Skeleton with Induction and Delocalization Effects for High Photocatalytic H2 Evolution

Molecular skeleton modification has become a recognized method that can effectively improve the photocatalytic performance of g-C3N4 because it not only effectively promotes charge separation, but also tunes the conjugated system of g-C3N4 to make it more conducive to photocatalytic reaction. Herein, thiophene-amide embedded g-C3N4 (TA-CN-x) was successfully prepared by simple one-step thermal polycondensation using urea as a precursor and ethyl-2-amino-4-phenylthiophene-3-carboxylate (EAPC) as an additive. After embedding with thiophene-amide, the induction and delocalization effects are formed in TA-CN-x, which significantly improves the migration efficiency of photogenerated charge carriers. Meanwhile, the conjugate structure is changed due to structural modification, resulting in significant enhancement of visible light absorption compared to the pure g-C3N4 (CN). Specifically, the optimized photocatalytic H2 evolution rate of TA-CN-2 reaches 245.4 μmol·h−1, which is 8.4 times that of CN (with Pt nanoparticles as a co-catalyst), and the apparent quantum efficiency (AQY) at 450 nm is 13.6%. This work opens up a new modification process for fully tapping the photocatalytic hydrogen absorption potential of g-C3N4-based materials.

Characteristic of Molecular Subtypes in Lung Squamous Cell Carcinoma Based on Autophagy-Related Genes and Tumor Microenvironment Infiltration.

Background Recently, a large number of studies have sought personalized treatment for lung squamous cell carcinoma (LUSC) by dividing patients into different molecular subtypes. Autophagy plays an important role in maintaining the tumor microenvironment and immune-related biological processes. However, the molecular subtypes mediated by autophagy in LUSC are not clear. Methods Based on 490 LUSC samples, we systematically analyzed the molecular subtype modification patterns mediated by autophagy-related genes. The ssGSEA and CIBERSORT algorithm were utilized to quantify the relative abundance of TME cell infiltration. Principal component analysis was used to construct autophagy prognostic score (APS) model. Results We identified three autophagy subtypes in LUSC, and their clinical outcomes and TME cell infiltration had significant heterogeneity. Cluster A was rich in immune cell infiltration. The enrichment of EMT stromal pathways and immune checkpoint molecules were significantly enhanced, which may lead to its immunosuppression. Cluster B was characterized by relative immunosuppression and relative stromal activation. Cluster C was activated in biological processes related to repair. Patients with high APS were significantly positively correlated with TME stromal activity and poor survival. Meanwhile, high APS showed an advantage in response to anti-PD1 and anti-CTLA4 immunotherapy. Conclusion This study explored the autophagy molecular subtypes in LUSC. We also discovered the heterogeneity of TME cell infiltration driven by autophagy-related genes. The established APS model is of great significance for evaluating the prognosis of LUSC patients, the infiltration of TME cells, and the effect of immunotherapy.

Functionalized 0D-3D heterostructure with ameliorated charge separation kinetics enables efficient photocatalytic hydrogen evolution

The construction of heterojunctions with a rapid space charge separation mechanism is an effective means to improve the photocatalytic activity. In this work, QDs/NH2-MIL-101(Fe)-AP photocatalyst equipped with built-in electric field was rationally prepared by a molecular modification strategy. Electron-withdrawing effect of the pyridine ring facilitates the directional transfer of electrons from the internal part of NH2-MIL-101(Fe) to the heterojunction interface. Meanwhile, the electron self-driven effect incidental to the suitable conduction band positions of QDs and NH2-MIL-101(Fe)-AP, and the co-driving effect of electron transfer exerted by hydrogen bonding accelerate the electron enrichment in the conduction band of NH2-MIL-101(Fe)-AP. The photocatalytic hydrogen evolution results showed that QDs/NH2-MIL-101(Fe)-AP reached an optimum rate of 2991.0 µmol h−1 g−1. Moreover, fluorescence and electrochemical tests revealed that the significant increase in photocatalytic activity is attributed to the efficient spatial separation of the photoinduced charge carriers.

Boosting the Heterologous Expression of d-Allulose 3-Epimerase in Bacillus subtilis through Protein Engineering and Catabolite-Responsive Element Box Engineering.

As a natural sweetener with low calories and various physiological activities, d-allulose has drawn worldwide attention. Currently, d-allulose 3-epimerase (DAEase) is mainly used to catalyze the epimerization of d-fructose to d-allulose. Therefore, it is quite necessary to enhance the food-grade expression of DAEase to meet the surging market demand for d-allulose. In this study, initially, the promising variant H207L/D281G/C289R of Clostridium cellulolyticum H10 DAEase (CcDAEase) was generated by protein engineering, the specific activity and the T1/2 of which were 2.24-fold and 13.45-fold those of the CcDAEase wild type at 60 °C, respectively. After that, PamyE was determined as the optimal promoter for the recombinant expression of CcDAEase in Bacillus subtilis, and catabolite-responsive element (CRE) box engineering was further performed to eliminate the carbon catabolite repression (CCR) effect. Lastly, high-density fermentation was carried out and the final activity peaked at 4971.5 U mL-1, which is the highest expression level and could effectively promote the industrial production of DAEase. This research provides a theoretical basis and technical support for the molecular modification of DAEase and its efficient fermentation preparation.

De novo assisted AFB1-Specific monoclonal antibody sequence assembly and comprehensive molecular characterization

Despite their widely used and access as biological reagents in analytical methods, the detailed structural features for most of the antibodies were rarely known. Here, a new antibody for AFB1 with high specificity in constructing ELISA was studied in detail. The molecular structure and modification were elucidated mainly by nano-electrospray ionization mass spectrometry. The mass experiments, including MALDI-TOF MS, revealed complete and specific fragments, including antibody molecular weight, peptides, glycopeptide, and N-glycoform. By proteolytic treatment of pepsin and trypsin and high-resolution tandem-MS, the primary structure of the newly developed anti-AFB1 antibody was assembled by several rounds of Database search process assisted with the de novo results. The antibody CDR annotation and constraint-based multiple alignment tool were used to differentiate and align the sequences. The method uses only two proteases to generate numerous peptides for de novo sequencing. This artificial assembled AFB1-specific monoclonal antibody sequence was validated by comparison with the sequencing results of the immunoglobulin gene. The results showed that this method achieves full sequence coverage of anti-AFB1 monoclonal antibody, with an accuracy of 100% in the CDR regions of light chain and four amino acid mismatch in heavy chain. This simple and low-cost method was confirmed by treating a public dataset. The secondary structure information of intact antibody was also elucidated from the results of circular dichroism spectrum.

Design, synthesis, and biological evaluation of aromatic tertiary amine derivatives as selective butyrylcholinesterase inhibitors for the treatment of Alzheimer's disease

Butyrylcholinesterase (BChE) is recently regarded as a biomarker in progressed Alzheimer's disease (AD), the development of selective BChE inhibitors has attracted a great deal of interest and may be a viable therapeutic strategy for AD. Previously, an aromatic tertiary amine derivative (S17–1001) was screened and validated as a selective BChE inhibitor. Structured-based molecular modification guided the synthesis of 43 analogs. Biological test of cholinesterase inhibition, in vitro blood brain barrier permeation assay, neurotoxicity assay and neuroprotective effects assay indicated two optimal compounds 17c and 19c. Both compounds showed selective BChE inhibitory (hBChE < 20 nM, eeAChE > 10 μM), good BBB permeation and primary cell safety. Besides, 17c can dose-response protect cell from Aβ1−42 induced damage. It also demonstrated that 17c and 19c were able to restore cognitive impairment in vivo test. These data suggest that 17c and 19c represent promising candidate for follow-up in the drug-discovery process against AD.

Molecular evolution and functional modification of plant miRNAs with CRISPR.

Gene editing using clustered regularly interspaced short palindromic repeat/CRISPR-associated proteins (CRISPR/Cas) has revolutionized biotechnology and provides genetic tools for medicine and life sciences. However, the application of this technology to miRNAs, with the function as negative gene regulators, has not been extensively reviewed in plants. Here, we summarize the evolution, biogenesis, and structure of miRNAs, as well as their interactions with mRNAs and computational models for predicting target genes. In addition, we review current advances in CRISPR/Cas for functional analysis and for modulating miRNA genes in plants. Extending our knowledge of miRNAs and their manipulation with CRISPR will provide fundamental understanding of the functions of plant miRNAs and facilitate more sustainable and publicly acceptable genetic engineering of crops.

Enhanced photovoltaic performance of D-π-A organic sensitizers by simple fluorination of acceptor unit

A simple and facile molecular modification method is presented to enhance the photovoltaic and photoelectrochemical properties of D- π -A organic sensitizers. This modification is obtained by incorporating fluorine as an additional acceptor unit. By the electron-withdrawing ability of fluorine, the electron transfer to the anchoring group is promoted, which ultimately leads to a decrease in the HOMO-LUMO energy gap. In addition, the incorporated fluorine also induces prominent J -aggregation, resulting in an increase in the dye loading amount on the photoanode. Because of these positive effects, the additional fluorine acceptor enhances both the photocurrent and photovoltage of dye-sensitized solar cells (DSSCs). In particular, electrochemical impedance study reveals that the electron lifetime in the dye-sensitized photoanode also increases by the incorporation of fluorine in the dye molecules, mostly because of enhanced dye loading. • Simple fluorination leads to enhanced photovoltaic property of organic sensitizer. • Electron-withdrawing ability of fluorine extends light absorption range. • Fluorine also induces prominent J -aggregation, resulting in an increased dye loading. • Fluorine greatly enhances the conversion efficiency of DSSCs by about 29%.