Research progress on chemical modifications of tyrosine residues in peptides and proteins.

The chemical modifications (CMs) of protein is an important technique in chemical biology, protein-based therapy, and material science. In recent years, there has been rapid advances in the development of CMs of peptides and proteins, providing new approaches for peptide and protein functionalization, as well as drug discovery. In this review, we highlight the methods for chemically modifying tyrosine (Tyr) residues in different regions, offering a comprehensive exposition of the research content related to Tyr modification. This review summarizes and provides an outlook on Tyr residue modification, aiming to offer readers assistance in the site-selective modification of macromolecules and to facilitate application research in this field.

Effect of Indole-2-carboxylic Acid on the Self-Corrosion and Discharge Activity of Aluminum Alloy Anode in Alkaline Al-Air Battery.

Al-air battery has been regarded as a promising new energy source. However, the self-corrosion of aluminum anode leads to a loss of battery capacity and a decrease in battery longevity, limiting its commercial applications. Herein, indole-2-carboxylic acid (ICA) has been added to 4 M NaOH as a corrosion inhibitor. Its impact on the self-corrosion of aluminum alloy and the enhancement of the functionality of Al-air batteries at various concentrations have been investigated. X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) techniques have been used to examine the compositional and morphological alterations of aluminum alloy surfaces. Electrochemical and hydrogen evolution tests showed that indole-2-carboxylic acid is an efficient corrosion inhibitor in alkaline solutions, and its impact grows with concentration. Our findings demonstrated that when the inhibitor concentration is 0.07 M, the inhibition efficiency is 54.0%, the anode utilization rises from 40.2% to 79.9%, the capacity density increases from 1197.6 to 2380.9 mAh g-1, and the energy density increases from 1469.9 to 2951.8 Wh kg-1. In addition, theoretical calculations have been performed to support the experimental results.

GO-functionalized MXene towards superior anti-corrosion coating.

MXene flakes shows the great potential in corrosion protection area owing to their lamellar structure and remarkable mechanical features. However, these flakes are highly susceptible to oxidation, which results in their structure degradation and restrict their application in anti-corrosion field. Herein, graphene oxide (GO) was used to functionalize Ti3C2Tx MXene through TiOC bonding to fabricate GO-Ti3C2Tx nanosheets, which proved by Raman, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR). GO-Ti3C2Tx nanosheet inclusion into the epoxy coating and their corrosion performance in 3.5 wt.% NaCl solution with 5 MPa pressure was evaluated through electrochemical techniques including open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) along with salt spray. Results indicated that GO-Ti3C2Tx/EP presented superior anti-corrosion capability, the impedance modulus at low frequency (|Z|0.01 Hz) was above 108 Ω cm2 after 8 days' immersion in 5 MPa environment, which was 2 orders of magnitude higher than that of the pure epoxy coating. Scanning electron microscope (SEM) and salt spray images demonstrated that the epoxy coating loaded with GO-Ti3C2Tx nanosheet could provide robust corrosion protection for Q235 steel via the physical barrier effect.

Regulating the Anode Corrosion by a Tryptophan Derivative for Alkaline Al-Air Batteries.

Screening a green corrosion inhibitor that can prevent Al anode corrosion and enhance the battery performance is highly significant for developing next-generation Al-air batteries. This work explores the non-toxic, environmentally safe, and nitrogen-rich amino acid derivative, N(α)-Boc-l-tryptophan (BCTO), as a green corrosion inhibitor for Al anodes. Our results confirm that BCTO has an excellent corrosion inhibition effect for the Al-5052 alloy in 4 M NaOH solution. An optimum inhibitor addition (2 mM) has increased the Al-air battery performance; the corrosion inhibition efficiency was 68.2%, and the anode utilization efficiency reached 92.0%. The capacity and energy density values increased from 990.10 mA h g-1 and 1317.23 W h kg-1 of the uninhibited system to 2739.70 mA h g-1 and 3723.53 W h kg-1 for the 2 mM BCTO added system. The adsorption behavior of BCTO on the Al-5052 surface was further explored by theoretical calculations. This work paves the way for constructing durable Al-air batteries through an electrolyte regulation strategy.

Identification of immuno-infiltrating MAP1A as a prognosis-related biomarker for bladder cancer and its ceRNA network construction.

Backgrounds: Approximately 75% of bladder cancer occurrences are of the non-muscle-invasive type. The estimated five-year survival rate is 26%-55%. Currently, there is no reliable biomarker available for early diagnosis and prognosis of bladder cancer. The present study aims to identify a biomarker using bioinformatic approaches to provide a new insight in clinical research for early diagnosis and prognosis of bladder cancer. Methods: Clinical data and a transcriptome of bladder cancer were obtained from TCGA, GEO, GETx, and UCSC Xena. The differential expressed gene (DEG) analysis, weighted gene co-expression network analysis (WGCNA), and survival analysis using the Kaplan-Meier and Cox proportional-hazards models were used to identify the Microtubule-associated Proteins 1A (MAP1A). on overall survival (OS) and disease-free survival (DFS) was analyzed using GEPIA and GETx databases. The TIMER 2.0 database predicted the correlation between MAP1A and immunocytes and immune checkpoints. Target prediction of the regulated competing endogenous RNAs (ceRNAs) network of MAP1A was performed using starBase and TargetScan. Cystoscope v3.7.2 software was used to visualize the ceRNA coexpression network. The R programming language v4.0.2 was applied as an analytic tool. Gene expression of MAP1A verified by RT-qPCR. Results: The low expression of MAP1A was verified in bladder cancer tissues and bladder cancer cell lines SW780 and 5637. P < 0.001 were obtained by Kaplan-Meier survival analysis and Cox proportional hazards model, with a hazard ratio (HR) of 1.4. Significant correlations between MAP1A and OS (P < 0.001, HR = 1.9) as well as DFS (P < 0.05, HR = 1.7) in bladder cancer were identified through gene expression profiling interactive analysis (GEPIA), indicating MAP1A may be a high-risk factor. Significant correlation in single copy-number variation of MAP1A gene with CD8+ T cells, and myeloid dendritic cells (MDCs) (P < 0.05) was noted. MAP1A expression was shown to be significantly correlated with the amount of CD4+ T cells and CD8+ T cells, MDCs, macrophages, and neutrophils in a statistically significant positive manner (P < 0.001). However, the MAP1A expression demonstrated a strong negative connection with B cells (P < 0.001). Except for macrophage M1 genes IRF5 and PTGS2, MAP1A expression was significantly correlated with the gene levels in immunocytes such as CD4+ T cells, CD8+ T cells, B cells, dendritic cells (DCs), macrophages, and neutrophils (Cor > 0.2, P < 0.001), as well as immune checkpoint related genes including cytotoxic t-lymphocyte-associated protein 4 (CTLA-4), programmed death 1 (PD-1), programmed death ligand 1 (PD-L1) (P < 0.001). Finally, we predicted that the MAP1A-interacting miRNA was miR-34a-5p, and the MAP1A endogenous competing RNAs were LNC00667, circ_MAP1B, and circ_MYLK, respectively. These findings support the need for further studies on the mechanism underlying the pathogenesis of this disease. Conclusion: MAP1A is considered as a prospective biomarker for early diagnosis, therapeutic observation, and prognosis analysis in bladder cancer.

Comparative study on corrosion inhibition of N doped and N,S codoped carbon dots for carbon steel in strong acidic solution.

Carbon steel is the most widely used engineering material, and its corrosion is one of the main areas of concern in many industries. The most practical approach to control this problem is to use corrosion inhibitors. Currently, because of their good water solubility, excellent chemical stability, low cost and nontoxic features, carbon dots (CDs), especially heteroatom-doped CDs, have been developed as green corrosion inhibitors, but the corrosion inhibition efficiency and underlying mechanisms of single- or dual-element doping have not yet been accurately compared and analyzed. Inspired by this, eco-friendly nitrogen-doped and nitrogen, sulfur codoped CDs (N-CDs and N,S-CDs) are prepared via a one-step hydrothermal process, and a comparative study on their inhibition performance for carbon steel corrosion in strong acidic solution is performed. The results show that both N-CDs and N,S-CDs can restrain the corrosion of carbon steel, and their inhibition efficiency increases with increasing concentration and immersion time, reaching approximately 87.9% (N-CDs) and 96.4% (N,S-CDs) at 200 ppm after 1 h of immersion. Molecular dynamics simulation indicates that the strong interaction ability between N,S-CDs and the Fe substrate leads to higher corrosion inhibition performance than the single N doping case, benefiting from the multi-anchor adsorption of N,S-CDs on carbon steel in a strong acidic solution. Therefore, the facile preparation, eco-friendliness and high corrosion inhibition performance of N,S-CDs will provide a new approach for designing highly efficient carbon dots and broadening the application of carbon dots in the corrosion field.

The role of morphology, shell composition and protein corona formation in Au/Fe3O4 composite nanoparticle mediated macrophage responses.

The great interest in using nanoparticles (NPs) for biomedical applications is transversal to various materials despite the poorly understood correlation between their physicochemical properties and effects on the immune system. NPs, such as gold and Fe3O4, are generally regarded as safe, but the immunotoxicological profile of Au/Fe3O4 composite NPs with different physicochemical properties is not well documented. This study investigated the biological impact of Au/Fe3O4 composite NPs with different morphologies (spherical core-shell and flower-like) and shell composition in vitro to analyze their potential cytotoxic effects and inflammatory responses on RAW 264.7 cells. Au/Fe3O4 composite NPs with a flower-like structure (FLNPs) induce a pronounced reduction in cell viability compared with Au/Fe3O4 composite NPs with a spherical core-shell structure (CSNPs). The increased production of reactive oxygen species, which damages cellular membranes, might contribute to the cytotoxicity effect of FLNPs. However, CSNPs presented more RAW 264.7 cell adhesion and uptake than FLNPs. Remarkably, a significant TNF-α release was observed with CSNP treated RAW 264.7 cells other than that of FLNPs. Protein corona analysis revealed the adsorption of a distinct amount and profile of proteins on the surface of CSNPs and FLNPs. Given the similar particle size and ζ-potential of CSNPs and FLNPs under the cell culture condition, results indicate that the impact of Au/Fe3O4 composite NPs on the macrophage activity highly depends on their morphology, shell composition and protein corona profile.

Papaya leaves extract as a novel eco-friendly corrosion inhibitor for Cu in H2SO4 medium.

The papaya leaves were extracted via ultra-pure water. The obtained papaya leaves extract (PLE) was used as the eco-friendly inhibitor for Cu in the H2SO4 corrosion medium. The experimental results showed that PLE was a mixed-type inhibitor and exhibited excellent anti-corrosion nature over a certain temperature range. Morphological analysis test results at different temperatures strongly proved the anti-corrosion nature of PLE. The XPS test results found that an adsorption film of Cu-S bond and Cu-N bond was formed on the Cu surface. This barrier film conformed to Langmuir mono-layer adsorption. Corrosion kinetics and thermodynamic parameters were calculated and discussed.

Synthesis of Macromolecular Aromatic Epoxy Resins as Anticorrosive Materials: Computational Modeling Reinforced Experimental Studies.

Herein, two bifunctional macromolecular aromatic epoxy resins (ERs), namely, 4,4'-isopropylidenediphenol oxirane (ERH) and 4,4'-isopropylidene tetrabromodiphenol oxirane (ERBr), are synthesized, characterized, and evaluated as anticorrosive materials for carbon steel corrosion in acidic medium. ERs were characterized using proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy techniques. Investigated ERs acted as effective corrosion inhibitors, and their inhibition effectiveness followed the order ERBr (96.5%) > ERH (95.6%). Potentiodynamic polarization results showed that ERH and ERBr behave as predominantly anodic type and the cathodic type of corrosion inhibitors, respectively. Adsorption of both the studied ERH and ERBr molecules obeyed the Langmuir adsorption isotherm model. Density functional theory and molecular dynamics studies showed that protonated forms of ERH and ERBr contribute more to metal (carbon steel)-inhibitor (ERH/ERBr) interactions than their neutral forms.

Incorporation of electroconductive carbon fibers to achieve enhanced anti-corrosion performance of zinc rich coatings.

Zinc rich epoxy (ZRE) coatings can provide sacrificial anode protection for metal substrate. Electrically conductive fillers can be added into ZRE coatings to create electroconductive network and improve the utilization of zinc particles. Inspired by the structure of reinforced concrete, in this work, carbon fibers with a length of 2 mm, 5 mm, and 10 mm were used as electrically conductive fillers to drive more zinc particle into electrically conductive paths and to provide coatings with better mechanical properties. Without agglomeration, ZRE-10 can achieve an efficient protection for copper substrate up to 50 days in 3.5 wt% NaCl solution, much longer than that of ZRE coating. Moreover, the fraction of water absorbed by ZRE-10 is 14%, which for ZRE is 20%, and the adhesion strength of ZRE-10 increased by 65% compared with that of ZRE. All tests in this work can prove a remarkably enhanced anticorrosion performance and mechanical properties of ZRE coatings achieved by addition of longer carbon fibers.

An intermittent microwave-exfoliated non-expansive graphite oxide process for highly-efficient production of high-quality graphene.

Redox methods represented by Hummers' method are the most frequently-used pathways to prepare graphene, but to date still very low-efficient, because of its time-consuming washing and hard reduction process. Here we report an intermittent microwave-exfoliated non-expansive graphite oxide (GtO) process to prepare a wrinkled graphene with a high reduction degree (C/O: 19.0), a high defect degree, and a high specific surface area (1333.7 m2 g-1). Findings show that the non-expansive GtO without water washing indicates an almost 100% exfoliated success rate during this intermittent microwave process. The obtained graphene shows easy dispersity in organic solvents, and excellent supercapacitor performance in specific capacitance, rate capacity, and especially in cycling lifetime with no decay after 80,000 cycles at 30 A g-1. Consequently, this special microwave process successfully solves the problems of tedious washing and hard reduction in redox methods, thus exponentially boosting the efficiency of preparing graphene.

Corrosion inhibition of X65 steel in sulfuric acid by two food flavorants 2-isobutylthiazole and 1-(1,3-Thiazol-2-yl) ethanone as the green environmental corrosion inhibitors: Combination of experimental and theoretical researches.

Food flavors of 2-isobutylthiazole (ITT) and 1-(1,3-Thiazol-2-yl)ethanone (TEO) for the corrosion inhibition of X65 steel in H2SO4 were studied by electrochemical methods, atomic force microscopy (AFM), scanning electron microscopy (SEM) and theoretical calculations. Electrochemical experiments show that ITT and TEO can effectively inhibit the corrosion of cathode and anode of X65 steel, and they are mixed-type corrosion inhibitors. Surface topography analysis (SEM and AFM) also visually demonstrate that ITT and TEO form an effective barrier film on the X65 steel surface to isolate the corrosive medium. Theoretical calculations profoundly explain the inhibition mechanism of ITT and TEO at the molecular level. In addition, the adsorption behavior of ITT and TEO on the surface of X65 steel is consistent with Langmuir isotherm adsorption. The results of experimental and theoretical studies have shown that the inhibition effect of TEO is better than ITT for X65 in 0.5 M H2SO4.

Experimental and Theoretical Investigation of Thiazolyl Blue as a Corrosion Inhibitor for Copper in Neutral Sodium Chloride Solution.

The anticorrosion effect of thiazolyl blue (MTT) for copper in 3% NaCl at 298 K was researched by electrochemical methods, scanning electron-microscopy (SEM), and atomic force microscopy (AFM). The results reveal that MTT can protect copper efficiently, with a maximum efficiency of 95.7%. The corrosion inhibition mechanism was investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectral (FT-IR), and theoretical calculation. The results suggest that the MTT molecules are adsorbed on metal surface forming a hydrophobic protective film to prevent copper corrosion. It also indicates that the MTT and copper form covalent bonds. The molecular dynamic simulation further gives the evidence for adsorption. The adsorption isotherm studies demonstrate that a spontaneous, mixed physical and chemical adsorption occurs, which obeys Langmuir adsorption isotherm. The present research can help us better understand the corrosion inhibition process and improve it.

A combined experimental and theoretical study of the inhibition effect of three disulfide-based flavouring agents for copper corrosion in 0.5 M sulfuric acid.

Diallyl disulfide (DAD), propyl disulfide (PPD) and dibenzyl disulfide (DBD) flavouring agents as copper corrosion inhibitors in 0.5 mol/L H2SO4 solution were evaluated with multitudinous experiments including electrochemical techniques, morphological characterization measurements, FTIR spectra and theoretical calculations. The electrochemical results indicate that PPD and DBD show mixed-type inhibitors and DAD belongs to cathodic-type inhibitor, and the corrosion inhibition capacity follow order: PPD > DBD > DAD. The adsorption of these compounds on the surface of copper conforms to the Langmuir adsorption isotherm model. Furthermore, theoretical calculations were applied to deeply understand the inhibition mechanism of three disulfide-based compounds.

Hydrothermal Synthesis of a New Kind of N-Doped Graphene Gel-like Hybrid As an Enhanced ORR Electrocatalyst.

In this work, g-C3N4@GO gel-like hybrid is obtained by assembling intentionally exfoliated g-C3N4 sheets on graphene oxide (GO) sheets under a hydrothermal condition. A specific N-doping process is first designed by heating the g-C3N4@GO interlaced hybrid in vacuum to form nitrogen-doped graphene nanosheets (NGS) with high level of pyridinic-N (56.0%) and edge-rich defect structure. The prepared NGS exhibited a great electrocatalysis for oxygen reduction reaction (ORR) in terms of the activity, durability, methanol tolerance, and the reaction kinetics. And the excellent electrocatalytic performance stems from the effective N-doped sites that the nitrogen atom is successfully doped at the defective edges of graphene, and the annealing temperature can play significant role of the doping pattern and location of N. The research provides a new insight into the enhancement of electrocatalysis for ORR based on nonmetal carbons by using the novel N-doping method.

Halogeno-substituted indazoles against copper corrosion in industrial pickling process: a combined electrochemical, morphological and theoretical approach.

The inhibitive properties of four indazole-based compounds (IA, 4-FIA, 4-CIA, and 4-BIA) on copper corrosion in 0.5 M H2SO4 solution were investigated using electrochemical measurements, surface characterization techniques and molecular modelling methods. Electrochemical tests indicate that the inhibition efficiencies increase with incremental concentration and all halogeno-substituted indazoles (HIAs) possess superior inhibitive ability to native IA. The specific rating of inhibition performance obeys the order: IA < 4-FIA < 4-BIA < 4-CIA. All inhibition efficiencies of HIAs obtained were over 96% in 1 mM, especially, 4-CIA reaches 99.6%. Moreover, the corresponding inhibition mechanism was elucidated via quantum chemical calculations allied to molecular dynamics simulation. In summary, the present study can help us to gain insight into the effect of halogeno-substitution on the inhibition efficiency of the IA molecule.

Toward understanding the anticorrosive mechanism of some thiourea derivatives for carbon steel corrosion: A combined DFT and molecular dynamics investigation.

The mutually corroborated density functional theory (DFT) and molecular dynamics (MD) simulation methodology were employed to evaluate the inhibition performance of three thiourea derivatives (Inh1, Inh2, and Inh3) on carbon steel corrosion. Experimental results have shown that the corrosion rate follows the order: Inh3>Inh2>Inh1. Quantum chemical descriptors such as the frontier orbital energies (EHOMO and ELUMO), the energy gap between ELUMO and EHOMO (ΔE), dipole moment (µ), and Fukui index have been calculated and discussed. Some significant factors such as solvent, temperature, and coverage have been considered when investigating the adsorption of aforementioned thiourea derivatives on Fe(110) surface. Our results provide important atomic/molecular insights into the anticorrosive mechanism of inhibitor molecules, which could help in understanding the organic-metal interface and designing more appropriate organic corrosion inhibitors.

Synergistic effect of tartaric acid with 2,6-diaminopyridine on the corrosion inhibition of mild steel in 0.5 M HCl.

The inhibitive ability of 2,6-diaminopyridine, tartaric acid and their synergistic effect towards mild steel corrosion in 0.5 M HCl solution was evaluated at various concentrations using potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS), and weight loss experiments. Corresponding surfaces of mild steel were examined by atomic force microscope (AFM), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) analysis. The experimental results are in good agreement and reveal a favorable synergistic effect of 2,6-diaminopyridine with tartaric acid, which could protect mild steel from corrosion effectively. Besides, quantum chemical calculations and Monte Carlo simulation were used to clarify the inhibition mechanism of the synergistic effect.

Experimental and theoretical studies on the corrosion inhibition of copper by two indazole derivatives in 3.0% NaCl solution.

Corrosion experiments and theoretical calculations were performed to investigate the inhibition mechanism of indazole (IA) and 5-aminoindazole (AIA) for copper in NaCl solution. The results obtained from weight loss and electrochemical experiments are in good agreement, and reveal that these compounds are high-efficiency inhibitors with inhibition efficiency order: AIA>IA, which was further confirmed by field emission scanning electronic microscope (FESEM) observation. Besides, the quantum chemical calculations and molecular dynamics (MD) simulation showed that both studied inhibitors are adsorbed strongly on the copper surface in parallel mode. The adsorption of these molecules on copper substrate was found to obey Langmuir isotherm.