Structural Characterization Research Articles

Effect of thermal annealing on the luminescent and structural properties of the SiOxCy thin films by organic catalytic chemical vapor deposition

Photoluminescent silicon oxycarbide (SiOxCy) thin films were deposited on n-type (100) silicon substrates using the organic catalytic chemical vapor deposition (O-Cat-CVD) technique employing tetra-ethyl orthosilicate (TEOS) as an organic-based precursor. These films were annealed at a temperature of 500, 800 and 1000°C for 30 minutes in a nitrogen (N2) environment. The as-deposited and annealed SiOxCy films were analyzed using optical and structural characterizations, such as photoluminescence (PL), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Secondary ion mass spectrometry (SIMS) and scanning electron microscopy (SEM). The PL spectrum of the as-deposited film showed emission in the blue-green region, while the annealed SiOxCy films showed strong emission from blue to near-infrared. The PL in all the films was attributed to different structural defects related to oxygen and carbon that act as radiative centers in the SiOxCy network. The annealed films showed an increase in the emission intensity, where the annealed film at 800°C displayed the highest emission intensity. This is related to an increase in the amount of radiative defects in the films due to structural and compositional changes after the thermal annealing (TA). XPS and SIMS measurements showed an oxygen incorporation with the TA, increasing from 54.59 at. % to 63.5 at. % for the as-deposited and annealed at 1000°C films, respectively. FTIR spectra showed an increase in the Si-O-C and Si-O-Si bonds and the hydrogen and other radicals desorption. These results support the creation of radiative centers due to structural changes in the films after the thermal annealing.

Separation, purification, structure characterization, and immune activity of a polysaccharide from Alocasia cucullata obtained by freeze-thaw treatment

In this study, ACP-1, a water-soluble polysaccharide was isolated from the roots of Alocasia cucullata (AC) using freeze-thaw treatment (FTT). Structural characterization revealed ACP-1 (2.10×105 Da) to be a homogeneous heteropolysaccharide primarily consisting of glucose, galactose, and arabinose, and a trace of fucose, rhamnose, and glucuronic acid. Methylation analysis and nuclear magnetic resonance spectroscopy revealed that the backbone of ACP-1 consisted of →[3)-β-D-Galp-(1]4→3,6)-β-D-Glcp-(1→3,6)-β-D-Glcp-(1→, with a branch at C-3. In vitro experiments demonstrated that ACP-1 significantly enhanced the proliferation and phagocytosis of RAW264.7 cells, upregulated the expression of co-stimulatory molecules (CD80 and CD86), and activated RAW264.7 cells via the nuclear factor kappa-B signal transduction pathway, resulting in nitric monoxide release and the secretion of the cytokines tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. Overall, ACP-1 shows potential as a novel immunostimulant.

Exploring the therapeutic potential of polysaccharide from Portulaca oleracea L.: A review of phytochemistry and immunomodulatory effect

Portulaca oleracea L., a plant with both edible and medicinal properties, is traditionally valued for its diuretic, antipyretic, antiseptic, antispasmodic, and anthelmintic functions in folk medicine. P. oleracea polysaccharide (POP), a pivotal bioactive component, has various biological activities. Notably, their immunomodulatory capabilities have emerged as a significant area of research. The extraction, purification, monosaccharide composition, structure characterization, and biological activity of POP have been extensively investigated to identify the active components and to clarify their pharmacological actions and underlying molecular mechanisms. It aims to delineate the pharmacological mechanisms and molecular pathways associated with these polysaccharides, thereby underscoring their therapeutic promise and nutritional significance. Furthermore, the review critically examines the current research landscape of POP, identifying gaps and proposing innovative perspectives to enrich the scientific discourse surrounding these bioactive compounds.

Structural characterization and potential antitumor and immunostimulatory activities of mycelial polysaccharides from Ophiocordyceps gracilis

Ophiocordyceps gracilis (O. gracilis), the same genus as Ophiocordyceps sinensis, has been used as an edible medicinal fungus for many years. However, the active ingredients of O. gracilis polysaccharides remain relatively unknown. To address this, a 310.1kDa novel polysaccharide (PDP-1a) was isolated from O. gracilis. The structural characteristics of PDP-1a were determined by different spectroscopy analyses, revealing that PDP-1a was α-glucan homologs with →4)-α-Glcp(1→ as the main chain. Furthermore, PDP-1a inhibited tumor cell proliferation, particularly in the A549 cell line, with a cell death mechanism involving cell cycle blockage, mitochondrial membrane potential reduction, and increased reactive oxygen species, thereby leading to apoptosis. Importantly, PDP-1a promotes antitumor cytokine secretion and enhances macrophage phagocytosis concentration-dependently. These findings provide a theoretical foundation for the use of O. gracilis and emphasize the potential application of PDP-1a in antitumor immunomodulatory therapy.

Whole mitochondrial genome sequencing and phylogenetic analysis of Gangetic mystus (Mystus cavasius)

Mystus cavasius, known as Gangetic mystus, is a freshwater indigenous catfish. The present study represents the first-ever complete mitochondrial genome sequencing of M. cavasius. The whole mitochondrial genome size is 16,554 bp (GenBank accession number OR018997). The mitogenome organization consists of total 37 genes, with 13 protein-coding genes, two rRNA, 22 tRNAs, and a D-loop regulatory region. Among these, 28 genes are coded on the heavy strand, while eight tRNA genes and ND6 are encoded separately. Phylogenetic analysis reveals that M. cavasius clusters with other Mystus species and bagrid catfishes. This work contributes valuable insights into structural characterization and phylogenetic relationships.

Unveiling the potent Antimicrobial Photodynamic Therapy in Gram-positive and Gram-negative bacteria – Water remediation with monocharged chlorins

Water pollution is a significant concern worldwide, and it includes contaminants such as antibiotic-resistant pathogens. Antimicrobial photodynamic therapy (aPDT) offers a non-invasive and non-toxic alternative for the inactivation of these microorganisms. So, this study reports the synthesis, structural characterisation, photophysical properties, and aPDT efficacy of cationic free-base and zinc(II) chlorin (Chl) derivatives bearing N,N-dimethylpyrrolydinium groups (H2Chl 1a and ZnChl 1b). The aPDT assays were performed against two bacterial models: Staphylococcus aureus (Gram-(+)) and Escherichia coli (Gram-(–)). The H2Chl 1a and ZnChl 1b distinct’s solubility profile, coupled with their ability to generate singlet oxygen (1O2) under light exposure, (H2Chl 1a, ФΔ = 0.58 <TPP, ФΔ = 0.65 < ZnChl 1b, ФΔ = 0.83) opens up their potential application as photosensitizers (PS) in aPDT. The effectiveness of H2Chl 1a and ZnChl 1b at 1.0 and 5.0 μM in aPDT against S. aureus and E. coli at 500 W.m–2 (total exposure time: 60 –120 min) showed a viability reduction > 6.0 log10 CFU.mL–1. Additionally, KI was used as a coadjuvant to potentiate the photoinactivation of E. coli, reaching the method’s detection limit (> 4.0 log10 RLU). As most of the PS developed to inactivate Gram-negative bacteria are cationic with three or more charges, the fact that the H2Chl 1a and ZnChl 1b with only one cationic charge photoinactivate E. coli at low concentrations and with a reduced light dose, it is an importing discovery that deserves further exploration. These monocharged chlorin dyes have the potential for water remediation.

Comprehensive Characterization of Micro-pore Structures in Different Lithologies of the Lacustrine Fine-grained Mixed Sedimentary Reservoir of the Shahejie Formation in the Jiyang Depression

Comprehensive Characterization of Micro-pore Structures in Different Lithologies of the Lacustrine Fine-grained Mixed Sedimentary Reservoir of the Shahejie Formation in the Jiyang Depression

Microstructural and mechanical characterization of steel-copper composite structures fabricated by laser powder bed fusion and induction melting

Microstructural and mechanical characterization of steel-copper composite structures fabricated by laser powder bed fusion and induction melting

Characterization of Microscopic Structures in Living Tumor by In Vivo Measurement of Magnetic Relaxation Time Distribution of Intratumor Magnetic Nanoparticles (Adv. Mater. 46/2024)

Characterization of Microscopic Structures in Living Tumor by In Vivo Measurement of Magnetic Relaxation Time Distribution of Intratumor Magnetic Nanoparticles (Adv. Mater. 46/2024)

An eco-friendly strategy for emerging contaminants removal in water: Study of the adsorption properties and kinetics of self-polymerized PHEMA in green solvents

Water contaminants severely affect human health and aquatic ecosystems, and adsorption poses an economic, available, and feasible technology for remediation that needs to be accompanied by eco-friendly and sustainable materials. This study proposes an eco-friendly strategy for removing emerging contaminants using polyhydroxyethyl methacrylate polymers synthesized by self-polymerization with hydrophilic first-generation deep eutectic solvents. The polymers were characterized using structural and physical characterization techniques and their adsorption capacity against four emerging contaminants: a non-steroidal anti-inflammatory drug, an antibiotic, a pesticide, and a non-ionic surfactant. The experimental results showed high adsorption capacity for the urea: choline chloride-derived polymer with 6.21, 7.19, 6.01, and 6.99 mg⋅g-1 for paracetamol, ciprofloxacin, glyphosate, and triton X-100, respectively; these values are comparable to those obtained for similar systems. Kinetic, isothermal, and thermodynamics were also studied using various mathematical models to understand the adsorption mechanism, further complemented by DFT analysis. Chemisorption was found to be the primary mechanism by exothermic and ordered processes, which is thermodynamically favored. The study demonstrated for the first-time the effectiveness of self-polymerized PHEMA without chemical modification as a reusable adsorbent material and its ability to remove different types of emerging contaminants, thereby offering a promising solution for water treatment in environmental science.

Fluoro-polymer/TiO2 based photocatalysts for hydrogen generation

In view of limited number of studies on photoreforming of synthetic polymers, herein, a series of new glycopolymers are synthesized via RAFT polymerization to obtain diblock copolymers containing fluorinated and non-fluorinated segments in the glucopyranoside. These glycopolymers are used as probes to investigate photocatalytic reactions at different pH values of the modulated TiO2 photocatalyst. Through structural and surface characterizations, photocatalytic activities are investigated. Fluoro-polymers with deacetylated glucose, hydrophilic segment, PGD such as PPFPM-b-PGD and PPFBM-b-PGD could synergistically increase hydrogen generation rate up to 1368 μmol g-1h−1 and 1549 μmol g-1h−1 with quantum yields of 3.34 % and 3.79 % compared to non-fluoro glycopolymers. The presence of both fluorinated and non-fluorinated groups in diblock copolymers enhanced the rate of photocatalytic hydrogen generation compared to the homopolymer. The accelerated photo-reforming is attributed to in-situ fluorine-doped TiO2 along with high affinity and activation of water molecules. These polymers can generate hydrogen via photo-reforming process.

A novel cocrystal of indole-3-propionic acid and nicotinamide: structure design, preparation, characterization and preliminary physiochemical properties evaluation

Indole-3-propionic acid (IPA), an intestinal microbiota produced metabolite, has been supposed as a promising clinical drug candidate to ameliorate progressive neurological and neuropsychiatric disorders associated with gut microbiota dysbiosis due to age-related infirmity. In this study, in order to enhance the aqueous solubility of IPA, nicotinamide (NIC) was selected as a coformer to synthesize a novel cocrystal (IPA-NIC) which was characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), thermal analysis, and Fourier transform infrared spectroscopy (FT-IR). The cocrystal structure was found to be in a 2:1 stoichiometric ratio consisting of four IPA molecules and two NIC molecules linked through heteromolecular hydrogen bonds within an asymmetric unit. The physiochemical properties of solubility, dissolution and permeability were demonstrated to be simultaneously improved. Preliminary forced studies under thermal (60 °C) and humid (92.5% RH) conditions indicated that the cocrystal remained stable which would be beneficial to the further development as a potential drug candidate.

Effect of B/Pb ion replacement in B2O3-PbO-SiO2 glasses: Structural, thermal, optical and electrical properties

Due to its easy manufacturing process and outstanding physical and chemical characteristics, boron lead silicate glass is widely used in electronic packaging, optical fields, and sensor technology. Herein, new glass samples with different proportions of B2O3/PbO are prepared by a combined melting and annealing process. The glasses undergo structural and thermal characterization to investigate its composition, thermal behavior, optical properties, and dielectric properties. The results show that the glass structure changes gradually as [SiO4] and [PbO4] units were replaced by [BO3] units with increasing B2O3 content. This transformation has an impact on coefficient of thermal expansion and characteristic temperature of the glass. Additionally, it is observed that alterations in structure resulted in a decrease in both optical band gap as well as dielectric constant and loss. These findings provide insights into how variations in the B2O3/PbO ratio influence structural evolution and enhance properties for boron lead silicate glasses. This provides a theoretical basis for further advances to improve material properties and expand optical and electronic applications.

Chemical Probes Review: Choosing the Right Path Towards Pharmacological Targets in Drug Discovery, Challenges and Future Perspectives.

Chemical probes are essential for academic research and target validation for disease identification. They facilitate drug discovery, target function investigation, and translation studies. A chemical probe provides starting material that can accelerate therapeutic values and safety measures for identifying any biological target in drug discovery. Essential read outs depend on their versatility in biochemical testing, proving the hypothesis, selectivity, specificity, affinity towards the target site, and valuable in new therapeutic approaches. Disease management will depend upon chemical probes as a primitive tool to ascertain the physicochemical stability for in vivo and in vitro studies useful for clinical trials and industrial application in the future. For cancer research, bacterial infection, and neurodegenerative disorders, chemical probes are integrated circuits which are on pipeline for the drug discovery process Furthermore, pharmacological modulators incorporate activators, crosslinkers, degraders, and inhibitors. Reports accessed depend on their structural, mechanical, biochemical, and pharmacological characterization in drug discovery research. The perspective for designing any chemical probes concludes with the utilization of drug discovery and identification of the potential target. It focuses mainly on evidence-based studies and produces promising results in successfully delivering novel therapeutics to treat cancers and other disorders at the target site. Moreover, natural product pharmacophores like rapamycin, cephalosporin, and α-lactamase are utilized for drug discovery. Chemical probes revolutionize computational-based study design depending on identifying novel targets within the database framework. Chemical probes are the clinical answers for drug development and goforward tools in solving other riddles for scientists and researchers working in this industries.

Unraveling distinct potential of pea (Pisum sativum L.) fractions (legumin, vicilin and albumin) by structural and functional characterization

Unraveling distinct potential of pea (Pisum sativum L.) fractions (legumin, vicilin and albumin) by structural and functional characterization

Adenine-originated N-doped C3N4 modified glassy carbon electrode for ultra-sensitive electrochemical quantification of cysteamine drug

Cystinosis is a rare autosomal recessive illness in which cystine accumulates in lysosomes, causing crystallisation in important organs. Cysteamine, the only approved therapy, demands precise concentration control because of its therapeutic importance. Cysteamine detection methods, including fluorescence spectroscopy, chemical etching, and HPLC, need sophisticated sample preparation and expensive equipment. Electrochemical sensing provides a simpler alternative with higher sensitivity and selectivity. However, traditional carbon electrodes have limited sensitivity and detection limits. Nitrogen (N-CN), sulfur (S-CN), and nitrogen/sulfur co-doped (N, S-CN) graphitic carbon nitride materials were produced using a one-pot calcination of adenine and methionine precursors. N-CN-modified glassy carbon electrodes demonstrated higher electrocatalytic activity, quicker electron transfer, and increased selectivity, sensitivity, and stability for cysteamine detection. Structural and morphological characterisation of the synthesised materials was performed using various analytical techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller plots, X-ray diffraction, and X-ray photoelectron spectroscopy. The sensor showed a linear relationship between anodic peak current and cysteamine concentration in the range of 0 µM to 1 mM, with a low detection limit of 82.5 nM (0.0825 µM). Moreover, the modified electrode exhibited good reproducibility and stability with a recovery rate of 95.5 % and a relative standard deviation (RSD < 5 %). Real-sample analysis revealed a good agreement between LSV and HPLC for detecting cysteamine in blood serum. The paper describes a unique metal-free N-CN synthesis utilising adenine, allowing effective electrochemical detection.

Structural characterization of an acid-extracted polysaccharide from Suillus luteus and the regulatory effects on intestinal flora metabolism in tumor-bearing mice

Suillus luteus is an excellent edible fungus that has been applied in soil remediation and environmental pollution control, while the development of bioactive polysaccharide component including structural performance and intestinal flora regulation is still insufficient. In this study, a S. luteus acid-extracted polysaccharide (SLAP) was prepared under room temperature, then the structural characteristics and regulatory effects on gut microbiota metabolism in tumor-bearing mice were investigated. Results showed that SLAP was a kind of gulcomannan (average molecular weight of 1.76 × 107 Da) comprised of Xyl, Man, Glc, Gal (molar ratio of 0.19:1.00:0.72:0.53), which took β-(1 → 4)-Manp and β-(1 → 4)-Glcp as the backbone with β-(1 → 6)-Glcp and α-(1 → 6)-Galp as branches. The animal experiment results demonstrated that SLAP could effectively enhance the immunoregulatory activities of CD4+ and CD8+ T cells in tumor-bearing mice via improving intestinal lactobacillaceae contents and promoting primary bile acids biosynthesis, finally leading to the suppression of solid tumors growth with an inhibitory rate of 61.14 % (100 mg/kg·d). These results would provide certain data support and research basis for further applications of SLAP as an immunomodulatory adjuvant in food and medicine fields.

Structural characterization of an arabinogalactan rich fraction from Bauhinia forficata link leaves and evaluation of its effect on THP-1 macrophages

Structural characterization of an arabinogalactan rich fraction from Bauhinia forficata link leaves and evaluation of its effect on THP-1 macrophages

Family GH157 enzyme exhibits broad linkage tolerance and a dual endo/exo- β -glucanase activity on β-glucans

The structural and chemical diversity of β-glucans is reflected on the variety of essential biological roles tackled by these polysaccharides. This natural heterogeneity requires an elaborate assortment of enzymatic mechanisms to assemble, degrade or modify, as well as to extract their full biotechnological potential. Recent metagenomic efforts have provided an unprecedented growth in potential new biocatalysts, most of which remain unconfirmed or uncharacterized. Here we report the first biochemical and structural characterization of two bacterial β-glucanases from the recently created glycoside hydrolase family 157 (LaGH157 and BcGH157) and investigate their molecular basis for substrate hydrolysis. Structural analysis by X-ray crystallography revealed that GH157 enzymes belong to clan GH-A, possessing a (β/α)8-barrel fold catalytic domain, two β-sandwich accessory domains and two conserved catalytic glutamates residues, with relative positions compatible with a retaining mechanism of hydrolysis. Specificity screening and enzyme kinetics suggest that the enzymes prefer mixed-linkage glucans over β-1,3-glucans. Activity screening showed that both enzymes exhibit pH optimum at 6.5 and temperature optimum for LaGH157 and BcGH157 at 25 °C and 48 °C, respectively. Product analysis with HPAEC-PAD and LC-MS revealed that both enzymes are endo-1,3(4)-β-glucanases, capable of cleaving β-1,3 and β-1,4-linked glucoses, when preceded by a β-1,3 linkage. Moreover, BcGH157 needs a minimum of 4 subsites occupied for hydrolysis to occur, while LaGH157 only requires 3 subsites. Additionally, LaGH157 possesses exohydrolytic activity on β-1,3 and branching β-1,6 linkages. This unusual bifunctional endo-1,3(4)/exo-1,3–1,6 activity constitutes an expansion on our understanding of β-glucan deconstruction, with the potential to inspire future applications.

Enzymatic bimetallic Cu-Ni micromotor sensor for xanthine detection

Enzymatic bimetallic Cu-Ni micromotors modified screen-printed electrodes were designed for the determination of xanthine. The bimetallic Cu-Ni micromotors were prepared by electrochemical template deposition. Morphological and structural characterization revealed that the smaller size and active mobility of the particles contribute to a larger specific surface area. The increase in surface area enhances electro-catalytic activities and sensitivity. These improved properties enable the newly created xanthine oxidase-modified Cu-Ni micromotors to function effectively as a high-performance sensor. Designed specifically for detecting xanthine, this sensor boasts high sensitivity, a broad measurement range, low detection limits, and excellent reproducibility and stability. The enzymatic bimetallic micromotor-based sensor was also successfully employed to measure xanthine levels. The limits of detection were determined to be 15.7 nM and 21.53 μM for xanthine concentration ranges of 0.1 μM–1 μM and 10 μM–300 μM, respectively, based on electrochemical signals under a magnetic field. Besides, the detection limit was calculated as 9.02 μM for xanthine concentrations ranging from 0.3 μM to 20 μM, based on the speed of the micromotors under a magnetic field (S/N = 3). The impressive results highlight the significant potential of bimetallic Cu-Ni micromotors as sensors, suggesting their promising applications in monitoring food freshness and enhancing security technology.