Ultraviolet-visible Absorption Spectroscopy Research Articles

A green plant-derived fluorescent polyphenol: Investigating the fluorescence properties of ellagic acid in diverse solvents

Ellagic acid (EA), a natural and environmentally friendly polyphenol, positively impacts human health and is widely used in the food and medical industries. It features a well-organized planar structure with an extensive sp2 carbon-conjugated area and four phenolic hydroxyl groups, making it favorable for light energy absorption and fluorescent emission. This positions EA as a promising candidate for advanced fluorescence applications. To date, the fluorescence properties of EA have not been thoroughly investigated. In this research, we comprehensively examined the fluorescence properties of EA in various solvents—including alkaline aqueous, alcoholic, nitrogenous, other organic solvents, and polyethylene glycols (PEGs)—using transient/steady-state fluorescence spectroscopy, ultraviolet–visible absorption spectroscopy, Fourier-transform infrared spectroscopy, and density functional theory calculations. Additionally, the relationship between structural changes of EA in these solvents and its fluorescence properties was deeply investigated. It was discovered that general solvation effects (solvent polarity effects), hydrogen bonding effects, and viscosity effects are the main ways that solvents alter the optical characteristics of EA. EA exhibits outstanding fluorescence characteristics in PEG400, creating a bright green fluorescence with the highest Stokes shift at 170 nm among the 32 organic solvents and alkaline aqueous solutions examined. This study is both foundational and essential, setting the stage for advancing the research on EA-based fluorescent materials in future endeavors.

Applications of Nanozymes in Chiral-Molecule Recognition through Electrochemical and Ultraviolet-Visible Analysis.

Chiral molecules have similar physicochemical properties, which are different in terms of physiological activities and toxicities, rendering their differentiation and recognition highly significant. Nanozymes, which are nanomaterials with inherent enzyme-like activities, have garnered significant interest owing to their high cost-effectiveness, enhanced stability, and straightforward synthesis. However, constructing nanozymes with high activity and enantioselectivity remains a significant challenge. This review briefly introduces the synthesis methods of chiral nanozymes and systematically summarizes the latest research progress in enantioselective recognition of chiral molecules based on electrochemical methods and ultraviolet-visible absorption spectroscopy. Moreover, the challenges and development trends in developing enantioselective nanozymes are discussed. It is expected that this review will provide new ideas for the design of multifunctional chiral nanozymes and broaden the application field of nanozymes.

Tetracycline degradation in the system of peracetic acid activation by liquid discharge plasma

The oxidative degradation ability of peracetic acid (PAA) for organic pollutants can be enhanced by different activation methods. This study investigated the degradation efficiency and mechanisms of tetracycline (TC) using PAA activated by liquid-phase discharge plasma. An 86.08 % degradation efficiency for TC after 60 min treatment was achieved in the Plasma/PAA system, much higher than that of the sole Plasma (46.64 %) and PAA (15.19 %). Acidic conditions and neutral conditions were more favorable for TC removal than alkaline conditions. Inorganic ions generally inhibited TC degradation, though notably, low concentrations of Cl− and NO3− promoted it. Free radical quenching experiments and electron paramagnetic resonance (EPR) analysis confirmed the crucial roles of OH, RO, and 1O2 in TC degradation. Three-dimensional fluorescence spectroscopy (3DFS) and ultraviolet–visible absorption spectroscopy (UV–VIS) elucidated the TC degradation mechanism, revealing key aspects of antibiotic structural decomposition. Further analysis of the degradation products by liquid chromatography-mass spectrometry (LC-MS) indicated three potential degradation pathways. Biotoxicity evaluations indicated that the synergistic system significantly reduced the biotoxicity of the degradation products. This study demonstrated an efficient method for plasma-activated PAA in degrading persistent pharmaceutical pollutants. It also confirmed the system’s applicability across a broad spectrum of organic pollutants and water bodies, highlighting its potential for a wide range of environmental protection applications.

Visible-light responsive CuO-ZnO nanostructure synthesized using Muntingia calabura extract for efficient H2O2 evolution and organic pollutant degradation

In this study, ZnO-CuO heterostructures were synthesized via a green approach using Muntingia calabura leaf extract with insights into the precursor ratio for enhanced photocatalytic performance. The synthesized materials were characterized by modern analytic methods, including X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, ultraviolet-visible absorption spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry, which elucidated the presence of CuO nanospheres and ZnO semi-cuboids. Thanks to a lower bandgap of 2.24 eV compared to pristine ZnO (2.82 eV), better visible light absorption, and longer charge lifetime, the optimal ZC16 sample, corresponding to a Cu:Zn ratio of 1:16, achieved a hydrogen peroxide production of 350.23 μM under visible light that was further increased to 478.98 μM with oxygen aeration. In addition, ZC16 also demonstrated excellent photodegradation performance towards malachite green (95.82 %) and tetracycline (97.78 %). Disclosure into the photocatalytic mechanism of both processes revealed the significant roles of active radicals, which have proven the environmentally friendly and cost-efficient synthesis pathway of ZnO-CuO heterostructures for environmental remediation and clean energy applications.

A study on structural and optical properties of the synthesized PVP capped Zinc Oxide Nanoparticles

Zinc Oxide Nanoparticles, capped with a polymer, have been effectively synthesized using a chemical precipitation method at a relatively low reaction temperature of 60 °C. The present study examines the structural and optical properties of ZnO Nanoparticles (NPs) that have been synthesized and capped with different weight percentages of PVP (Polyvinyl Pyrrolidone). To investigate these properties, advanced analytical techniques including X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Ultra Violet-visible (UV–vis) absorption spectroscopy are employed. The XRD analysis reveals that the synthesized ZnO samples have a hexagonal wurzite structure, regardless of adding capping agent. The Williamson-Hall (W-H) analysis, a commonly used method, estimates the strain present in synthesized materials. The SEM image depicts ZnO NPs that have a nearly spherical form and are seen to be agglomerated. The UV–vis absorption measurements demonstrate a phenomenon known as blue shift when compared to the absorption characteristic of bulk ZnO.

Enhancement of Calcium Chelating Activity in Peptides from Sea Cucumber Ovum through Phosphorylation Modification.

Recently, phosphorylation has been applied to peptides to enhance their physiological activity, taking advantage of its modification benefits and the extensive study of functional peptides. In this study, water-soluble peptides (WSPs) of sea cucumber ovum were phosphorylated in order to improve the latter's calcium binding capacity and calcium absorption. Enzymatic hydrolysis methods were screened via ultraviolet-visible absorption spectroscopy (UV-Vis), the fluorescence spectrum, and calcium chelating ability. Phosphorylated water-soluble peptides (P-WSPs) were characterized via high-performance liquid chromatography, the circular dichroism spectrum, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, surface hydrophobicity, and fluorescence spectroscopy. The phosphorus content, calcium chelation rate and absorption rate were investigated. The results demonstrated that phosphorylation enhanced the calcium chelating capacity of WSPs, with the highest capacity reaching 0.96 mmol/L. Phosphate ions caused esterification events, and the carboxyl, amino, and phosphate groups of WSPs and P-WSPs interacted with calcium ions to form these bonds. Calcium-chelated phosphorylated water-soluble peptides (P-WSPs-Ca) demonstrated outstanding stability (calcium retention rates > 80%) in gastrointestinal processes. Our study indicates that these chelates have significant potential to develop into calcium supplements with superior efficacy, bioactivity, and stability.

Green synthesis of gold nanoparticles using Pelargonium Graveolens leaf extract: characterization and anti-microbial properties (An in-vitro study)

Background In recent years, there has been a notable increase in the level of attention devoted to exploring capabilities of nanoparticles, specifically gold nanoparticles AuNPs, within context of modern times. AuNPs possess distinct biophysical properties, as a novel avenue as an antibacterial agent targeting Streptococcus Mutans and Candida Albicans. The aim of this study to create a nano-platform that has the potential to be environmentally sustainable, in addition to exhibiting exceptional antimicrobial properties against Streptococcus Mutans as well as Candida Albicans. Methods this study involved utilization of Pelargonium Graveolens leaves extract as a cost effective and environmentally sustainable approach for the green synthesis of AuNPs. Subsequently, physicochemical characteristics were assessed employing a variety of analytical methods, including as transmission electron microscopy, X-ray diffraction, Field Emission Scanning Electron Microscope, Zeta potential, Ultraviolet visible absorption spectroscopy, and Energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The antimicrobial efficacy against Streptococcus Mutans and Candida Albicans was evaluated. Nanoparticles of various shapes, including hexagonal, spherical, semi-spherical, and triangular, were synthesized. These nanoparticles exhibited a mean particle size of 294nm and demonstrated low degree of aggregation. These nanoparticles exhibited long-term stability and were capable of facilely combining with diverse bioactive compounds. Results The study demonstrated that AuNPs which is synthesized by green methods display potent antimicrobial properties. Conclusion Utilization of Pelargonium Graveolens AuNPs may exhibit a promising potential as an antibacterial agent against Streptococcus Mutans and Candida Albicans. Nanoparticles (NPs) have the potential to serve as a novel approach for addressing pathogen infections as well as for biomedical, dental and pharmaceutical purposes in the future.

Morphology-transforming AuNPs-based fluorescent probe for ultra-low sensitive detection of levofloxacin in urine samples at pH 7.0 through excimer formation

Fluorescent metal nanoparticles (MNPs) have garnered considerable interest in the realm of healthcare applications. Within this domain, we present a novel fluorescent sensor: Pamoic acid (PA) functionalized excitation-dependent gold nanoparticles (PA@AuNPs), designed to ascertain levofloxacin (LF) concentrations in human urine samples under pH 7.0 conditions. The synthesis of PA@AuNPs was achieved via a chemical reduction method employing PA as both a reducing and stabilizing agent. Validation of the successful synthesis of PA@AuNPs was conducted utilizing a suite of analytical techniques including X-ray diffraction (XRD), ultraviolet–visible absorption spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Microscopic examination via field emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) elucidated the spherical morphology of PA@AuNPs, with an average diameter ranging from 10 to 15 nm. Furthermore, atomic force microscopy (AFM) revealed an average surface roughness of 20.72 nm for PA@AuNPs. Thermal analysis results divulge that PA@AuNPs are highly stable up to 370 °C. The PA@AuNPs have shown more than 10-fold higher selectivity for LF in comparison with other commercially available antibiotics. The fluorescence emission intensity of PA@AuNPs (quantum yield (ΦF) 3.36 %) has shown enhanced redshift (436 → 497 nm; ∼61 nm) (λex 353 nm) upon the sequential addition of LF (0 → 100 µM) and achieved a lower detection limit (LoD = 36 nM; LoQ = 121 nM; Ka = 1.0457 × 104 M−1) with increased ΦF 18.96 %. This radiative process and fluorescence enhancement were confirmed by time-correlated single photon counting (TCSPC) measurement (4.89 → 5.36 ns). Interestingly, upon sensing LF, PA@AuNPs changed their morphology from spherical to octahedron and displayed an excimer formation through intermolecular π-π stacking. Furthermore, the stability of the complex, PA@AuNPs•LF which formed through coordination, by restoring the fluorescence intensity of PA@AuNPs•LF (turn on) in the presence of ethylenediamine tetraacetic acid (EDTA) (turn off) is demonstrated. The formation of the PA@AuNPs•LF complex was further confirmed by XRD analysis and FTIR spectroscopy. The HRTEM and FESEM validate that PA@AuNPs•LF have octahedral morphology with an average size of 20–30 nm, and the obtained moiré fringes in TEM images are due to the overlap of LF on the surface of PA@AuNPs. The AFM analysis divulges that PA@AuNPs•LF had a larger surface roughness (Sa = 26.91 nm). The experimentally attained zeta potential of PA@AuNPs (–12.6 mV) was further decreased (–17.6 mV) in the presence of LF, which confirms the interaction between PA@AuNPs and LF. The cell viability (82 %) in L929 Fibroblast cells augmented the biological applications of PA@AuNPs. The practicability of the fluorescent sensor probe was demonstrated in human urine samples with recovery ranges from 97.56 to 104.38 %.

Preparation and characterization of grouper bone peptides-calcium complex by lactic acid bacteria fermentation

In this study, grouper bone peptides-calcium complex (GPs-Ca) was prepared by lactic acid bacteria fermentation, and its structure and stability were analyzed. Response surface methodology (RSM) optimization was used to determine the optimal fermentation conditions as follows: 4% (v/v) inoculum size, 4.5 g/100 mL glucose addition and fermentation time 75 h,under which the soluble calcium content was 5953.61 mg/L and the peptide content was 21.75 mg/mL. The results of ultraviolet–visible absorption spectroscopy (UV) and fluorescence spectroscopy (Fs) showed a significant spectral shift for GPs-Ca relative to grouper bone peptides (GPs), indicating that peptide combined with calcium to produce a new substance after fermentation. Fourier transform infrared spectroscopy (FTIR) showed that carboxyl groups participated in the formation of GPs-Ca. Scanning electron microscopy (SEM) showed that calcium ions were embedded or adsorbed on the peptide surface. According to the stability analysis, GPs-Ca was stable during heating, alkaline environment and intestinal digestion, but easily dissociated in acidic environment. GPs-Ca prepared by lactic acid bacteria fermentation has the potential to be used as a new type of calcium supplement product, which provides a scientific basis for the high-value utilization of grouper bone.

Synthesis, Characterization, and Properties of a Titanium(IV)-Tetrathiafulvalene-Based Complex.

To deeply investigate the interaction between a tetrathiafulvalene (TTF) unit and a Ti(IV) center, a monomeric heteroleptic octahedral Ti(IV) complex containing a diimine ligand composed of a 1,10-phenanthroline core fused with a TTF fragment (ligand 2a) was prepared. The stable complex formulated as Ti(1)2(2a), where 1 is a 2,2'-biphenolato derivative, was efficiently synthesized by following a one-step approach. This complex and its model species [Ti(1)2(2b)] were fully characterized in solution, and their solid-state structures were established by single-crystal X-ray diffraction analysis. Density functional theory calculations allowed the assignment of the frontier orbitals involved in the electronic transitions characterized by ultraviolet-visible absorption spectroscopy. Electrochemical and spectroelectrochemical studies revealed that the TTF unit within Ti(1)2(2a) can undergo two reversible one-electron oxidation processes; a reversible one-electron reduction of the Ti(IV) atom was highlighted. The photophysical measurements performed for this donor-acceptor molecular system indicated that an electron transfer process upon light excitation occurred within Ti(1)2(2a).

Green synthetic biomaterials: Synthesis, characterization and antimicrobial properties of lichen-derived nanomaterials

The green synthesis of nanoparticles using lichen extracts offers a safer and more environmentally friendly alternative to traditional methods. Known for their medicinal properties, lichens can effectively reduce and stabilise metallic salts, providing an eco-friendly approach to producing nanomaterials with potential antimicrobial applications. In this study, the lichen Rhizoplaca chrysoleuca was utilised in the green synthesis of nanoparticles, successfully creating lichen-derived silver-zinc oxide (Ag–ZnO), silver-strontium oxide (Ag–SrO), and silver-nickel oxide (Ag–NiO) nanoparticles. Ultraviolet–visible absorption spectroscopy revealed that the characteristic light absorption of the NCs occurred within the range of 300–400 nm for each synthesis, and dynamic light scattering measurements indicated that the hydrodynamic diameters of the nanoparticles were below 100 nm. Energy-dispersive X-ray spectroscopy confirmed the presence of the constituent elements. Imaging with field-emission scanning electron microscopy and scanning transmission electron microscopy showed that the nanoparticles had spherical shapes with dimensions measuring below 50 nm. X-ray diffraction analysis of the synthesised nanocomposite materials revealed the presence of Ag–ZnO (22 nm), Ag–SrO (48 nm), and Ag–NiO (21 nm) nanoparticles. Fourier-transform infrared spectroscopy identified functional groups in the nanoparticles, confirming their compositions, while thermogravimetric analysis determined the thermal decomposition temperatures of the NCs. The antibacterial efficacy of these materials was assessed, with Ag–ZnO (inhibition zone 11.0 mm) and Ag–NiO (inhibition zone 10.0 mm) showing significant effectiveness against both Gram-negative and Gram-positive bacteria. In contrast, Ag–SrO (inhibition zone 6.5 mm) exhibited comparatively lower antibacterial activity. Additionally, the study highlighted the antifungal properties of Ag–NiO (inhibition zone 19.0 mm) and Ag–ZnO (inhibition zone 8.5 mm) nanomaterials. This research advances the understanding of lichen-based nanotechnology and its potential for developing sustainable antimicrobial solutions.

Rational design of CdS-enwrapped polypyrrole nanoparticles for wastewater treatment: removal of hazardous pollutants in aqueous solutions.

The modern world requires a chemical industry that can run at low production costs while producing high-quality products with minimal environmental impact. The development of environmentally friendly, cost-effective, and efficient wastewater treatment materials remains a majorproblem for the sustainable approach. We prepared nanoscale cadmium sulfide (CdS)-enwrapped polypyrrole (PPy) polymer composites for degradation of organic pollutants. The prepared CdS@PPy nanocomposites were characterized by powder X-ray diffraction, scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet-visible(UV) absorption spectroscopy, indicating proper intercalation between CdS and PPy. Consequently, the catalytic efficiency of the synthesized hybrid nanocomposites was analyzed through the degradation of methylene blue (MB) and rhodamine B (Rh B) under visible light irradiation. The measured degradation efficiency of the dye solutions under the photolysis process is about 18% and 23% for MB and Rh B dye, respectively. Furthermore, the recycle test result concludes that the CdS@PPy composite exhibits 91% and 89% of MB and Rh B dye degradation efficiency even at the 4th cycle, respectively. The positive synergistic impact of CdS and PPymay be the result of effective photocatalytic degradation of MB and RhB.

Assessment of the in Vitro Effects of Folate Core-Shell Conjugated Iron Oxide Nanoparticles as a Potential Agent for Acute Leukemia Treatment.

There is a growing need to comprehend the potential outcomes of nanoparticles (NPs) on human well-being, including their potential for detecting and treating leukemia. This study examined the role of iron folate core-shell and iron oxide nanoparticles in inducing apoptosis and altering the expression of the B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X-protein (Bax), and Caspase-3 genes in leukemia cells. The obtained iron oxide and iron folate core-shell nanoparticles were analyzed using a variety of analytical techniques, including ultraviolet-visible (UV-Vis) absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential, and transmission electron microscopy (TEM). Additionally, FTIR and UV-Vis were used to characterize doxorubicin. The MTT test was utilized to investigate the cytotoxicity of iron oxide and iron folate core-shell nanoparticles. The expression of the apoptotic signaling proteins Bcl-2, Bax, and Caspase-3 was evaluated using the real-time reverse transcription polymerase chain reaction (RT-qPCR) method. Additionally, flow cytometry was performed to gauge the degrees of necrosis and apoptosis. UV-Visible spectroscopy analysis showed that the generated iron oxide and iron folate core-shell NPs had a distinctive absorption curve in the 250-300 nm wavelength range. The XRD peaks were also discovered to index the spherical form with a size of less than 50 nm, which validated the crystal structure. The FTIR analysis determined the bonds and functional groups at wavenumbers between 400 and 4000 cm-1. A viable leukemia treatment approach is a nanocomposite consisting of iron and an iron folate core-shell necessary for inhibiting and activating cancer cell death. The nearly resistant apoptosis in the CCRF-CEM cells may have resulted from upregulating Bax and Casepase-3 while downregulating Bcl-2 expression. Our study documents the successful synthetization and characterization of iron oxide, which has excellent anticancer activities. A metal oxide conjugation with the nanoparticles' core-shell enhanced the effect against acute leukemia.

An aberrant fused in sarcoma liquid droplet of amyotrophic lateral sclerosis pathological variant, R495X, accelerates liquid–solid phase transition

Intracellular aggregation of fused in sarcoma (FUS) is associated with the pathogenesis of familial amyotrophic lateral sclerosis (ALS). Under stress, FUS forms liquid droplets via liquid–liquid phase separation (LLPS). Two types of wild-type FUS LLPS exist in equilibrium: low-pressure LLPS (LP-LLPS) and high-pressure LLPS (HP-LLPS); the former dominates below 2 kbar and the latter over 2 kbar. Although several disease-type FUS variants have been identified, the molecular mechanism underlying accelerated cytoplasmic granule formation in ALS patients remains poorly understood. Herein, we report the reversible formation of the two LLPS states and the irreversible liquid–solid transition, namely droplet aging, of the ALS patient-type FUS variant R495X using fluorescence microscopy and ultraviolet–visible absorption spectroscopy combined with perturbations in pressure and temperature. Liquid-to-solid phase transition was accelerated in the HP-LLPS of R495X than in the wild-type variant; arginine slowed the aging of droplets at atmospheric conditions by inhibiting the formation of HP-LLPS more selectively compared to that of LP-LLPS. Our findings provide new insight into the mechanism by which R495X readily forms cytoplasmic aggregates. Targeting the aberrantly formed liquid droplets (the HP-LLPS state) of proteins with minimal impact on physiological functions could be a novel therapeutic strategy for LLPS-mediated protein diseases.

Spatiotemporal dynamics of dissolved organic matter in subtropical karst cave waters identified by optical properties

Natural dissolved organic matter (DOM) is ubiquitous in aquatic environments and is an essential component in the carbon cycle in karst areas. To improve understanding of the carbon cycle in karst caves with heterogeneous hydrological processes, we examined the spatiotemporal variability of DOM composition and further uncovered its source and fate. Results may also provide insights into the feedbacks of organic carbon to carbon sinks in karst regions. In this study, concentrations and compositions of DOM, partial pressure of aqueous carbon dioxide (pCO2), dissolved inorganic carbon, and other physicochemical parameters were investigated in a karst cave at Mahuang, Southwest China. Ultraviolet-visible absorption spectroscopy was coupled with multiple statistical analyses to identify the compositional variations and potential fates of DOM in cave waters. The results showed that DOM dynamics were regulated by both terrigenous and biogenic drivers under the control of meteorological conditions. With higher air temperature, precipitation, and microbial activity, fulvic fractions were consumed to generate CO2, leading to the accumulation of refractory DOM in cave waters and changing the hydrochemical features. When temperature and precipitation decreased, DOM was dominated by lignin fractions, which served as an indicator of terrestrial inputs and vascular plants, suggesting variation in the preferential fraction of biological consumption. In addition, different hydrological path patterns influenced DOM properties in cave waters due to differences in recharging, the leaching process, and subsurface reworking. Thus, hydrology could serve as an important constraint on the coupling between dissolved organic and inorganic carbon.

The interaction between troxerutin and pepsin was studied by multispectral method and molecular docking simulation

The mechanism of action and quenching mode between troxerutin and pepsin were investigated in this study using ultraviolet-visible absorption spectroscopy, Fourier transform infrared spectroscopy, fluorescence spectroscopy, three-dimensional fluorescence spectroscopy, synchronous fluorescence spectroscopy, circular binary chromatography, and molecular docking simulation. The fluorescence spectroscopy results demonstrated a reduction in the fluorescence intensity of pepsin upon addition of troxerutin, indicating its quenching effect on pepsin. By employing the Stern-Volmer equation to determine KSV and Kq values, it can be inferred that troxerutin exhibits static quenching as the predominant mode of interaction with pepsin. By conducting experiments, the binding constant KA and the number of binding sites n for troxerutin and pepsin were determined, with the number of binding sites n being close to 1, indicating the presence of a specific binding site between troxerutin and pepsin. Thermodynamic analysis was employed to calculate the thermodynamic parameters at 298 K. The negative values of ΔH and ΔS suggest that van der Waals forces and hydrogen bonding are predominant in mediating the interaction between troxerutin and pepsin. The negativity of ΔG indicates the spontaneity of the reaction. The results of molecular docking simulations demonstrate that troxerutin binds to the central active region of pepsin, with hydrogen bonds, van der Waals forces, hydrophobic interactions and adverse collisions contributing to the binding forces between troxerutin and pepsin. Based on the analysis of UV–vis absorption spectrum, three-dimensional fluorescence spectrum, synchronous fluorescence spectrum, and infrared spectrum, it is evident that troxerutin modulates the microenvironment surrounding tryptophan amino acid residues in pepsin. This modulation leads to a reduction in polarity and hydrophilicity while increasing hydrophobicity, consequently inducing alterations in the secondary structure of pepsin. By measuring the binding distance, it is calculated that 0.5 R0 < r < 1.5 R0 and r < 7 nm, indicating the occurrence of non-radiative energy transfer between troxerutin and pepsin. Analysis of the circular dichroism spectrum confirms that pepsin predominantly adopts a β-folded (β-sheet) conformation, providing evidence for the interaction between troxerutin and pepsin. Furthermore, troxerutin induces alterations in the microenvironment of pepsin's structure, ultimately resulting in changes to its secondary structure. These findings shed light on the binding mechanism underlying troxerutin and pepsin interactions while offering valuable reference data for future research and applications involving troxerutin.

Detection of ferric ions by nitrogen and sulfur co-doped potato-derived carbon quantum dots as a fluorescent probe

This paper reports the detection of ferric ions (Fe3+) based on nitrogen and sulfur co-doped carbon quantum dots. These nitrogen and sulfur co-doped carbon quantum dots were synthesized via a hydrothermal route using northern Shaanxi potatoes as carbon sources and ammonium sulfate as nitrogen and sulfur sources. The quantum yields of the carbon quantum dots were found to be 16.96% and 4.23% with and without doping, respectively. The structural details, morphology, and optical properties of carbon quantum dots were analyzed using Fourier transform infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV–vis), and fluorescence spectroscopy. The as-prepared co-doped carbon quantum dots were utilized as a fluorescent probe for detecting Fe3+ ions, where the fluorescence intensity of carbon quantum dots was remarkably quenched in the presence of Fe3+ ions. A good linear relationship for Fe3+ ion detection was obtained from 0 to 500 μmol/L with a detection limit as low as 0.26 μmol/L. Furthermore, the proposed method also provided satisfactory results in the tap water.

Determination of pesticide residue in soil samples by molecularly imprinted solid-phase extraction method

Abstract Porous molecularly imprinted polymer (MIP) microspheres were synthesized via iniferter-suspension polymerization method, employing lenacil (LA) as the template molecule and methacrylic acid (MAA) as the functional monomer. The host–guest complexes formed using LA and MAA were characterized by hydrogen nuclear magnetic resonance and ultraviolet–visible absorption spectroscopy. The obtained results showed that the interaction between LA and MAA mainly relied on hydrogen bonding. The surface morphologies and chemical structures of the MIPs were characterized by scanning electron microscopy. MIPs were spherical in shape with a relatively regular sphericity, rough surface structure, and numerous small holes, which significantly reduced the mass transfer resistance of the template molecules and exhibited excellent recognition performance for template molecules. In addition, soil samples were pretreated with solid-phase extraction columns molecularly imprinted with LA, and analyzed by high-performance liquid chromatography. The recoveries of LA, bromacil, and terbacil were up to 89.65%, 53.17%, and 44.63%, respectively. The developed method showed a minimum detection limit of 10–50 µg·mL−1. In view of the continuous increase of public requirements for pesticide residue detection, a versatile pretreatment method was developed that is green, rapid, simple, and can be miniaturized.

Facile process of Hibiscus mucilage polymer formulation using Hibiscus rosa-sinensis leaves to treat second-degree burn and excision wounds

Mucilage is a sticky substance found in various plants and microorganisms and is made up of proteins and polysaccharides. Mucilage from Hibiscus rosa sinensisis is a complex polysaccharide traditionally used to treat different skin diseases. In our study, we fabricated mucilage polymer from Hibiscus rosa sinensis leaves and evaluated its potential application in second-degree burns and excision wounds. The physical properties of Hibiscus mucilage (HM) polymer were demonstrated by using Ultraviolet-visible absorption spectroscopy, x-ray diffraction, Fourier transform infrared spectroscopy, dynamic light scattering, Scanning electron microscopy, Brunauer–Emmett–Tellerand, Swelling ratio. The human cell lines WI-38, and HaCaT have been used for in-vitro experiments like MTT, scratch wound, BrdU, ROS scavenging assays, and western blot analysis. The results of the MTT, scratch-wound, and BrdU assay indicated that the HM polymer is nontoxic in nature and also enhances both the properties of cellular migration and proliferation, respectively. On the other hand, the result of the ROS scavenging assay suggested that HM polymer enhances the antioxidant activity of cells while the western blot analysis designated that the HM polymer treatment caused downregulation of the pro-inflammatory cytokine IFN-γ and upregulation of the pAkt (Serine 473) protein, and TGF-β1 signaling pathway. Therefore, all in-vitro experimental studies recommended that HM polymer is biocompatible and has antioxidant and anti-inflammatory effects. In the in vivo experiment, second-degree burns and excision wounds were created on the dorsal surface of male BALB/c mice. After the sixth day of HM polymer treatment have developed new tissue, hair follicles, blood vessels, α-SMA, and Collagen type-1 fiber on the burn and excision wound area while the 11th day of HM polymer treatment cured the wound area significantly. Therefore, it could be contemplated that HM polymer is a potential agent for treating different wounds in the near future.

Comprehensive undergraduate experiment: synthesis and chromism of 4-[bis(4-methylphenyl)amino] benzaldehyde

To solve the problems of the lack of property research in organic synthesis experiments and the relative independence of instrumental analytical methods in experiments, we designed a comprehensive undergraduate experiment based on mechanofluorochromic materials. In this project, 4-[bis(4-methylphenyl)amino] benzaldehyde was synthesized via the Vilsmeier-Haack reaction using 4,4'-dimethyltriphenylamine as the raw material. The product was then characterized by mass spectrometry, infrared absorption spectroscopy, and nuclear magnetic resonance spectroscopy. The solvatofluorochromism and mechanofluorochromism of the target material were studied using ultraviolet-visible absorption spectroscopy, fluorescence spectroscopy, etc. Furthermore, the mechanism of mechanofluorochromism was determined using powder X-ray diffraction. Organic synthesis and a series of instrumental analytical methods were combined to form an integrated experiment. The experiment is interesting, scientific, and comprehensive for undergraduates as a creative exercise; moreover, it can inspire their interest in chemical research, cultivate a variety of experimental operation abilities, improve creative-thinking skills, and encourage the development of effective solutions to existing problems in chemical experiments.