UV Vis Spectroscopy Research Articles

Eco-friendly corrosion inhibition of steel using phenolic compounds from Cynara syriaca

This study evaluates the corrosion inhibition performance of the n-butanol (n-BuOH) fraction derived from Cynara syriaca on mild steel in acidic environments. The n-BuOH fraction achieved up to 94 % inhibition at 500 ppm, as assessed through gravimetric analysis, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Key phenolic compounds, including kaempferol, naringenin, myricetin, chlorogenic acid, and quercetin, were identified by UPLC-MS/MS. These compounds form stable flavonoid-metal complexes, as confirmed by UV–Vis spectroscopy. FT-IR and SEM-EDS analyses revealed the formation of protective coatings and interactions with the steel surface. Polarization curves indicate that the n-BuOH fraction acts as a mixed-type inhibitor, predominantly affecting the anodic reaction. The inhibition efficiency decreased from 93.89 % to 73.43 % with increasing temperatures. Thermodynamic analysis showed an increase in activation energy (Ea = 58.20 kJ/ mol) and a positive ΔH value of 56.17 kJ/mol, which can be attributed to the increased thickness of the double layer, enhancing the activation energy of the corrosion process. A Gibbs free energy (ΔG0ads) value of −25.48 kJ/mol confirms that the adsorption process is spontaneous and involves both physisorption and chemisorption. pKa analysis identified specific adsorption sites. This research underscores the potential of the n-BuOH fraction as a novel, eco-friendly corrosion inhibitor, offering valuable insights for sustainable corrosion control strategies.

Application of biogenic silver nanoparticle incorporated nanofibers in biomedical science

The applications of nanotechnology are expanding into medical science for designing new medical devices related products. These products can deliver targeted therapies to diseases such as cancer and peripheral artery treatment. Therefore, with the goal to treat peripheral artery disease, we integrated biogenic silver nanoparticles (AgNPs) into polyethylene glycol-polycaprolactone (PEG-PCL) nanofibrous (NFs). The AgNPs-NFs mats were successfully fabricated using a blended electrospinning process. AgNPs with average sizes of 35–55 nm were produced and characterized using multiple techniques such as UV–Vis spectroscopy, TEM, SEM and FTIR. Nanofibrous membranes containing 1 %, 2 %, and 3 % AgNPs by weight were developed, showing a reduction in fiber diameter from 473 nm to 179 nm due to the introduction of charged particles. The scaffold’s suitability and drug release profile were critically analyzed, revealing results consistent with optimal biomedical applications. Preliminary studies indicated that AgNPs dose-dependent inhibition of human umbilical vein endothelial cells (HUVECs) may potentially help prevent atherosclerosis. These findings underscore the potential of AgNPs integrated PEG-PCL NFs mats for advanced biomedical applications.

Development of pH-sensitive chitosan/plant extract microcapsules: Enhanced corrosion protection for carbon steel in HCl solution

In recent years, controlled-release green corrosion inhibitors have become a research hotspot in the field of corrosion. In this study, chitosan/plant extract microcapsules (GCI@CS) loaded with Ambrosia artemisiifolia extract (green corrosion inhibitor, GCI) were prepared by emulsification cross-linking. Both the functional groups and micromorphology of GCI@CS were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and optical microscopy (OM). The loading capacity and encapsulation efficiency of GCI@CS were analyzed using UV–Vis spectroscopy. The corrosion inhibition performance of GCI@CS on carbon steel (C-steel) in 1.0 mol/L HCl was investigated using electrochemical impedance spectroscopy (EIS). The results indicated that GCI@CS, as a pH-sensitive microcapsule, can provide effective corrosion protection for C-steel in HCl solution. Notably, the corrosion resistance of GCI@CS improved with increasing concentration and time. The corrosion inhibition efficiency (ηEIS) of C-steel immersed in 1.0 mol/L HCl (with 500 mg/L GCI@CS) for 24 h reached 93.48 %. This study provides important insights for the industrial deployment of green corrosion inhibitors with controlled release properties.

Designing of amiloride loaded citrate functionalized amorphous silica nanoparticles to investigate its genotoxic and cytotoxic potential

In the present work, silica-based nanocarrier for the anticancer drug, amiloride have been synthesized and characterized using various physicochemical techniques. The aim of this work emphasis on investigating the physicochemical properties and cytotoxic effects of citrate-functionalized amiloride loaded silica nanoparticles. Silica nanoparticles synthesis was carried out via condensation reaction, then coated by tris sodium citrate, followed by their functionalization using amiloride through EDC-NHS reaction. SEM and HR-XRD analysis indicated the formation of amorphous spherical silica nanoparticles. The existence of citrate coating was evident from FT-IR and TGA results, which were supported by DLS and zeta potential studies. The formation of amiloride conjugated citrate coated silica nanoparticles (SiNPs-Cit@Ami) was confirmed by the DLS, Zeta potential and UV-Visible spectroscopy. Size of SiNPs-Cit@Ami nanoparticles was found to be around 80nm using TEM. Additionally, these nanoparticles showed high loading efficiency and time-dependent release of amiloride. DNA binding studies were examined using UV–Visible, Fluorescence spectroscopic and Competitive fluorescence studies. The results indicate that SiNPs-Cit@Ami bind to Ct-DNA via minor groove binding mode. Furthermore, the cytotoxic effect of SiNPs-Cit@Ami on HepG2 cell lines was found to be higher than amiloride alone. Our findings suggest that SiNPs-Cit@Ami can be employed as a promising candidate for cancer mitigation.

A Simple, Cost-Effective, and Sustainable Method for Extraction and Quantification of Chebulagic Acid from Terminalia bellirica (Gaertn.) Roxb. Using RP-HPLC: A Comparative Study

Chebulagic acid (CA), a hydrolysable tannin found in Terminalia bellirica (T. bellirica) (Gaertn.) Roxb., has gained prominence as a significant component in Ayurvedic medicine. This study optimized methods for determining CA in T. bellirica, focusing on fruit samples and prioritizing simplicity, cost-effectiveness, less time duration, and sustainability. We evaluated various extraction techniques, including continuous shaking, microwave assisted extraction, and Soxhlet extraction using green solvents. Quantification of CA was conducted using Reverse Phase High-Performance Liquid Chromatography (RP-HPLC), with confirmation achieved via UV-Visible (UV-Vis) spectroscopy, Thin Layer Chromatography (TLC), and Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS). Results indicated that Soxhlet and microwave significant extraction methods, particularly with ethanol as the green solvent. Soxhlet extraction yielded 49607.73±18.82 μg/mL for fresh fruit and 42952.53±19.09 μg/mL for dry fruit, while microwave extraction resulted in 43627.56±113.48 μg/mL for fresh fruit and 40466.33±130.90 μg/mL for dry fruit respectively. These findings conclude that ethanol as a green solvent in Soxhlet or microwave assisted extraction emerge as most efficient, straightforward, and effective approach for detecting and screening CA in T. bellirica samples.

A comprehensive study on the bioactive flavonoids in Paulownia flowers: Uncovering metabolic pathways, effective components, and regulatory genes for industrial applications

The study explores Paulownia flowers as an emerging resource in medicine, food, health supplements, cosmetics, and animal feed, despite a lack of characterization of their secondary metabolite accumulation mechanisms. We conducted a comprehensive investigation into the biological activities, metabolite profiles, and gene expression patterns of flavonoids in Paulownia flowers. Our results, obtained using ABTS/FRAP/DPPH assays, MTT assays, and colorimetric analyses, demonstrate the potent antioxidant, antibacterial, hypolipidemic, and antiproliferative activities of Paulownia flower flavonoid (PFF) extracts. Notably, the Paulownia elongata tetraploid (M4) exhibited particularly notable effects. HPLC fingerprinting, molecular docking, and density functional theory calculations led to the identification of rhoifolin and luteolin as key bioactive flavonoids. UV-Vis, fluorescence, and circular dichroism spectroscopy confirmed PFF's role as a reversible and mixed inhibitor of xanthine oxidase (XOD). Transcriptome and metabolomic analyses further revealed substantial enrichment in phenylpropanoid, flavonol, and flavonoid biosynthetic pathways, with PfPP2C, PfPYR, PfPYL, PfNPR1, PfMYBs, and PfbHLHs identified as crucial regulators. This work provides a foundational understanding of flavonoid biosynthesis in Paulownia flowers, paving the way for targeted genetic modification and biotechnological interventions aimed at enhancing flavonoid accumulation for industrial applications.

Toxic Dye Degradation Employing Phoenix dactylifera Seed Extract for the Green Synthesis of Silver Nanoparticles: Characterization and Application.

This research highlights the facile green synthesis of silver nanoparticles (AgNPs) using Phoenix dactylifera seed extracts and its photocatalytic application for the degradation of toxic dyes. The AgNPs synthesis was confirmed by the appearance of its representative absorption peak at 416 nm in UV-visible absorption spectroscopy. Moreover, the reduction of silver ions to Ag was justified through Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction pattern revealed crystalline AgNPs structure with particle size ranging from 5 to 15 nm calculated using the Debye-Scherrer equation. The rectangular-like structural morphology of synthesized AgNPs was observed in scanning electron micrographs. The as-synthesized AgNPs demonstrated higher photocatalytic activity for the degradation of malachite green (MG) and congo red (CR) followed by methylene blue (MB), and crystal violet (CV) under UV irradiation. In addition, rate constant (k) and percentage degradation were also calculated. The present study presents a facile green synthesis pathway and its potentially successful manipulation in the reduction of toxic dyes under the illumination of UV-light.

Constructing ZnO/NiO Nanocomposites as a Photocatalyst and Investigating Photocatalytic Effectiveness for Wastewater Treatment.

The goal of the present work is to create ZnO/NiO nanocomposites (NCs) for the photocatalytic destruction of organic contaminants using the co-precipitation technique. To investigate physiochemical characteristics, FT-IR, UV visible spectroscopy, SEM, and XRD were used. The ZnO hexagonal phase and the NiO cubic phase in the ZnO/NiO NCs were verified by the diffraction pattern. NCs were discovered to have larger average crystallite sizes. The bandgap energy calculated from the Tauc plot for the ZnO is 3.02 and 2.74 eV for the ZnO/NiO NC's. SEM analysis revealed the morphological study and particle size was calculated using the histogram technique and found to be 124.5 nm for the ZnO and 49.2 nm for the ZnO/NiO NCs. Photocatalytic degradation in the presence of sunlight showed 72.8% degradation of Methylene blue (MB) for the ZnO and 79.2% for the ZnO/NiO NCs. The increase in the photocatalytic capablity for the NCs is attributed to the synergistic effect between ZnO and NiO which effectively separated charge carriers preventing greater recombination rate. The robustness of ZnO/NiO NCs as a catalyst option was shown by their exceptional performance.

Characterization of HPMC and PEG 400 Mucoadhesive Film Loaded with Retinyl Palmitate and Ketorolac for Intravaginal Administration

Intravaginal drug administration offers several advantages over other routes, primarily bypassing the initial stages of metabolism. Additionally, this route has demonstrated both local and systemic effects. Mucoadhesive polymeric systems can be utilized to prevent dose loss due to the mucous barriers and the formation of wet cavities. This study employed various techniques to evaluate the performance and characteristics of a mucoadhesive film composed of HPMC-PEG 400 containing retinyl palmitate and ketorolac molecules. Scanning Electron Microscopy (SEM) was employed to analyze the porous structure of the film. Thermogravimetric Analysis (TGA) was conducted at different temperatures to assess thermal stability. Fourier Transform Infrared Spectroscopy (FTIR) was used to analyze the functional groups and intermolecular interactions between the film and the drug. Swelling and weight loss tests indicated that the film disintegrated within 3–4 days. UV-VIS spectroscopy was used for drug release evaluation based on the Higuchi equation. Additionally, the surface wetting properties were assessed through contact angle measurements. The system’s biocompatibility was confirmed using the MTT assay. Finally, adhesion and glide tests demonstrated the film’s interaction with porcine uterine tissue. This study shows that the HPMC-PEG 400 film containing retinyl palmitate molecules interacts effectively with tissue and could be considered a novel tool for treating damaged epithelial tissues.

Amplified Cascade Catalysis for RAFT Polymerization.

We report a conceptually new amplified cascade catalysis that converts oxygen to hydroxyl radical for controlled RAFT polymerization. This catalysis consists of two sequential reactions, deoxygenation catalyzed by glucose oxidase and Fenton reaction catalyzed by ferrocene. The two catalysts can communicate with each other, leading to ferrocene recycling and hence amplification in radical generation. Ferrocene recycling was confirmed by UV-vis spectroscopy, molecular docking simulation, electron paramagnetic resonance spectroscopy, as well as polymerization studies. This catalysis was applied to RAFT polymerization of various monomers, yielding well-defined homopolymers and diblock copolymers with controlled molecular weights and low dispersities. Poly(N,N-dimethyl acrylamide) with molecular weight over 1 million g mol-1 was also successfully synthesized under ambient conditions. Ferrocene-functionalized microspheres were prepared and used as recyclable Fenton catalyst for five consecutive polymerizations with minimal declination in monomer conversion, which further improved the ecofriendly character of this polymerization methodology.

Continuity of Short-Time Dynamics Crossing the Liquid-Liquid Phase Separation in Charge-Tuned Protein Solutions.

Liquid-liquid phase separation (LLPS) constitutes a crucial phenomenon in biological self-organization, not only intervening in the formation of membraneless organelles but also triggering pathological protein aggregation, which is a hallmark in neurodegenerative diseases. Employing incoherent quasi-elastic neutron spectroscopy (QENS), we examine the short-time self-diffusion of a model protein undergoing LLPS as a function of phase splitting and temperature to access information on the nanosecond hydrodynamic response to the cluster formation both within and outside the LLPS regime. We investigate the samples as they dissociate into microdroplets of a dense protein phase dispersed in a dilute phase as well as the separated dense and dilute phases obtained from centrifugation. By interpreting the QENS results in terms of the local concentrations in the two phases determined by UV-vis spectroscopy, we hypothesize that the short-time transient protein cluster size distribution is conserved at the transition point while the local volume fractions separate.

Unleashing of cytotoxic effects of thymoquinone-bovine serum albumin nanoparticles on A549 lung cancer cells

Abstract This research examines the cytotoxic consequences of thymoquinone-loaded bovine serum albumin nanoparticles (TQ-BSA NPs) on the A549 lung cancer cell line. UV-visible (UV–Vis) spectroscopy, Fourier transform infrared spectrophotometer (FT-IR), scanning electron microscopy (SEM), and dynamic light scattering (DLS) were employed to verify the biogenic TQ-BSA NPs’ size, shape, and distribution. UV–Vis spectrophotometry indicated peaks at 200–300 nm, 500–600 nm, and a prominent peak at 700–800 nm, confirming the presence of TQ-BSA NPs. The polydispersity index, as confirmed by DLS, indicated a solvent distribution in water, accompanied by a zeta potential value of 126.2 ± 46.8 mV. The average size of TQ-BSA NPs was confirmed to be 187 ± 8 nm by SEM. TQ-BSA NPs reduce colony formation in the A549 lung cancer cell line in a dose-dependent manner relative to the control group. Protein expression analysis indicated that TQ-BSA NPs promoted programmed cell death by increasing pro-apoptotic levels and decreasing anti-apoptotic levels. TQ-BSA NPs demonstrated inhibition of cancer cell proliferation and promotion of apoptosis and exhibited significant efficacy against cancer cells at low concentrations. As a result, they have the makings of a promising chemotherapeutic agent for low-dose, long-term administration.

Tailoring Optical Performance of Polyvinyl Alcohol/Crystal Violet Band-Pass Filters via Solvent Features

Optical filters are essential components for a variety of applicative fields, such as communications, chemical analysis and optical signal processing. This article describes the preparation and characterization of a new optical filter made of polyvinyl alcohol and incremental amounts of crystal violet. By using distinct solvents (H2O, dimethyl sulfoxide (DMSO) and H2O2) to obtain the dyed polymer films, new insights were gained into the pathway that underlies the possibility of tailoring the material’s optical performance. The effect of the dye content on the sample’s main properties was inspected via UV–VIS spectroscopy analysis combined with colorimetry, refractometry and atomic force microscopy experiments. The results revealed that the colorimetric parameters are affected by the dye amount and are dramatically changed when the solvent used for film preparation is different. The rise in the refractive index upon polymer dyeing was due to the synergistic effect of the larger polarizability of the dye and the occurrence of hydrogen bonds among the system components. Spectral data evidenced that samples prepared in H2O and DMSO preserve the absorption characteristics of the added dye, whereas H2O2 acts as an oxidizing agent and enhances transparency. Also, for the first two solvents, multiple absorption edges were noted as a result of dye incorporation, which was responsible for the occurrence of new exciton-like states, hence the band gap reduction. The films processed in H2O were able to block radiations in the 506–633 nm range while allowing other wavelengths to pass with a transmittance above 90%. The samples attained in DMSO presented similar properties, with the difference that the domain of light attenuation was shifted towards higher wavelengths. Atomic force microscopy showed the dye’s effect on the level of surface roughness uniformity and morphology isotropy. The dyed polymer foils in non-oxidizing agents have suitable features for use as band-pass filters.

Hydrothermal synthesis of tungsten oxide photo/electrocatalysts: precursor-driven morphological tailoring and electrochemical performance for hydrogen evolution and oxygen reduction reaction application.

A hydrothermal approach was adopted to synthesize tungsten oxide (WO3) nanocatalysts with tailored morphology, using oxalic acid (H2C2O4) and hydrochloric acid (HCl) as precursors. This precursor-driven method yielded two distinct WO3 catalysts with unique structural and functional properties, viz. rod-shaped WO3-ox and nanoflower-shaped WO3-h. Characterization by FESEM and XRD revealed variations in morphology and crystallite size, contributing to their specialized catalytic applications. UV-Vis spectroscopy confirmed strong UV absorption by WO3-ox at 283.57nm with an optical band gap of 2.86eV, making it ideal for photocatalytic activities. Electrochemical analysis demonstrated that WO3-ox effectively drives the hydrogen evolution reaction (HER), while WO3-h is more suitable for the oxygen reduction reaction (ORR), an essential process in microbial fuel cells (MFCs). In practical applications, WO3-ox achieved an 83.9% degradation efficiency of methylene blue (MB) within 3h, validating its high photocatalytic efficacy for wastewater treatment. Meanwhile, WO3-h, utilized as a cathode catalyst in MFCs, significantly enhanced system performance, elevating chemical oxygen demand (COD) removal efficiency to 78.7% and improving coulombic efficiency by 3%. These findings underscore the potential of precursor-driven hydrothermal synthesis for optimizing WO3 catalysts tailored for energy and environmental applications, specifically in hydrogen production and sustainable wastewater treatment systems.

Cochineal (Dactylopius coccus Costa) Pigment Extraction Assisted by Ultrasound and Microwave Techniques

Carminic acid is a natural pigment typically found in several insect taxa, including specific insects such as “grana cochinilla fina” in Mexico (Dactylopius coccus Costa). Commercially, it is also referred to as carmine, which is a more concentrated solution presenting as at least 50% carminic acid. To date, this dye has been used in the pharmaceutical, food and cosmetic industries. Unfortunately, one of the main limitations has to do with establishing the appropriate extraction and purification protocol. Currently, there is growing interest in developing eco-friendly and efficient pigment extraction processes for various applications. In this study, we compare the ultrasound- and microwave-assisted extraction versus with a conventional method to obtain carminic acid from cochineal. To do this, we considered three factors that influence the extraction process as independent variables: solvent volume, temperature and irradiation time. The optimization was carried out using the response surface methodology, employing a three-factor and three-level Box–Behnken experimental design. Carminic acid contents were quantified by UV–Vis spectroscopy, and extracts were evaluated by infrared spectroscopy to verify the integrity of the carminic acid molecule. The yield obtained by ultrasound-assisted extraction was 49.2 ± 3.25, with an efficiency of 31.3 mg/min, while microwave-assisted extraction showed a yield of 40.89 ± 2.96, with an efficiency of 27.3 mg/min. Both methods exceeded the extract yield (31.9 ± 3.4%) and efficiency (10.6 mg/min) obtained with the conventional method, demostrating that ultrasound- and microwave-assisted extraction are viable alternatives for obtaining carminic acid, with the potential to be scaled up to an industrial level.

Forward-Scattering and Multiple-Scattering Sources of Errors in UV-Visible Spectroscopy of Microspheres.

Conventional UV-visible spectroscopy instruments measure the extinction spectrum of solutions in a transmission configuration. Because of the finite (nonzero) acceptance angle in detection, errors due to forward scattering and multiple scattering can be introduced when measuring scattering samples. We here experimentally quantify these errors using polystyrene spheres of different sizes for two representative analytical/research UV-visible instruments, one based on a single-beam diode array and the other on a double-beam scanning configuration. The measured spectra for particles larger than 1 μm are shown to differ between the two instruments, even at low concentrations, and also vary with concentration (in contradiction with the Beer-Lambert law). We show that systematic errors in the range of 10-40% are common in such measurements. We propose a model accounting for both forward- and multiple-scattering errors and demonstrate its agreement with our experimental results. This model could reduce systematic errors in measurements of scattering samples by up to 40%.

Chemical characteristics of BTEX, Formaldehyde and Trace gases: concentration, ozone formation potential and source apportionment at a campus site of Agra.

Benzene, toluene, ethylbenzene, xylenes (BTEX) and formaldehyde (HCHO) impact the environment and human health due to their deleterious effect and are of great concern. In the present study, diurnal and seasonal trend of BTEX and HCHO along with trace gases are reported. BTEX samples were collected by activated charcoal tubes and analysed by Gas Chromatograph coupled with Mass Spectrometer and Flame Ionization Detector (GC-MS/FID) and formaldehyde sampling was done by impinger method and analysed by UV-Visible Spectroscopy. Summation BTEX varied from 50.3 to 188.3µgm-3 (average = 74.8 ± 31.8µgm-3). Amongst all species, toluene was the most abundant. Highest levels of BTEX, NOx and CO were observed in winter (96.4 ± 39.1µgm-3, 11.9 ± 7.8ppb and 540.8 ± 402.0ppb respectively) probably due to enhanced local emissions, stagnant weather conditions resulting in dilution and dispersion of pollutants and weak photochemical removal. Lower values are seen during monsoon (58.6 ± 25.4µgm-3, 7.6 ± 6.1µgm-3 and 149.8 ± 68.7µgm-3) as a consequence of rain showers and washout effect leading to clean atmospheric conditions. Further, ozone forming potential (OFP) BTEX was determined based on their reactivity with OH˙radical and concentration. Toluene (90.9µgm-3) was the largest contributor to ozone formation, whereas benzene (9.1µgm-3) was the lowest. Source apportionment of BTEX was determined based on estimation of diagnostic ratios, correlations and positive matrix factorization (PMF) analysis and revealed emissions from vehicles was the main source. Air mass back trajectory analysis for different seasons shows the impact of long-range during the summer season and localized air masses during winter season. The results of the current study provide a better understanding of OFP and sources of BTEX and HCHO to formulate effective pollution management.

Doxorubicin-loaded core@shell cobalt ferrite-barium titanate magnetoelectric nanofibers for improved anticancer activity.

Conventional drug delivery systems often suffer from non-specific distribution and limited therapeutic efficacy, leading to significant side effects. To address these challenges, we developed magnetoelectric, cobalt ferrite@barium titanate (CFO@BTO) nanofibers, with a core-shell structure for targeted anticancer drug delivery. The electrospinning method was employed to synthesize polymeric nanofibers based on magnetoelectric core-shell nanostructures. The Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM) analysis confirmed the successful loading of nanostructures on polymeric nanofiber, the core-shell morphology and magnetoelectric phase of cobalt ferrite@barium titanate CFO@BTO, respectively. To verify the drug attachment, the optimization of drug release in an applied external magnetic field, and the time required for control drug release, UV-Vis spectroscopy was used. The effectiveness of magnetic field-assisted controlled drug release was demonstrated by achieving a 95 ± 1.03% drug release from magnetoelectric nanofibers (MENFs) within 30 minutes under a magnetic field of 4mT. In vitro cytotoxicity assay on human skin cancer (SK-MEL-28) cell lines exhibited a maximum 90 ± 2% cytotoxicity with 2±0.03 cm of drug loaded MENFs. Furthermore, the Hemolysis assay was carried out to affirm the biocompatibility and non-toxicity of drug loaded MENFs, which is suitable for anticancer therapy.

Bioactive Silk Revolution: Harnessing Curcuminoid Dye and Chitosan for Superior Antimicrobial Defence and UV Shielding

Background/Objectives: The use of natural colourants is gaining attention due to their biocompatibility and functional benefits. This study introduces a different approach using turmeric (Curcuma longa L.) dye extract combined with chitosan to significantly enhance the antibacterial and UV-shielding properties of silk. Methods: The turmeric dye’s chemical composition was analyzed using liquid chromatography mass spectrometry (LC-MS), UV–visible spectroscopy, and Fourier-transform infrared spectroscopy (FTIR). The dyed silk’s colourfastness was tested through rubbing, washing, and light exposure. Results: The chitosan-mordanted silk showed strong antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as well as antifungal activity against Aspergillus niger (A. niger). It also demonstrated a high ultraviolet protection factor (UPF). For comparison, alum-mordant was used, and chitosan proved more effective. Beyond its use as a dye, turmeric is renowned for its medicinal properties. Its antioxidant, anticancer, and anti-inflammatory properties have been extensively researched, which are primarily linked to its curcuminoid compounds. Turmeric is used in traditional medication to treat digestive issues, arthritis, and skin diseases. Conclusions: This work underscores the innovative use of plant-based dye extracts and natural mordants like chitosan as a sustainable alternative to conventional metallic mordants, paving the way for the evolution of bioactive silk with improved functional properties.

Highly Conductive Multifunctional Iron‐Incorporated Polythiophene Nanocomposite: A Nanocatalyst for Nitrobenzene Reduction in Aqueous Medium and an Efficient Room Temperature Methanol Gas Sensor

ABSTRACTThis study reports the synthesis and application of a polythiophene–iron oxide (PTh‐Fe0‐Fe2O3) nanocomposite as a highly effective catalyst for the selective reduction of nitro aromatics in an aqueous environment. The nanocomposite was synthesized using in situ chemical polymerization, with Fe0‐Fe2O3 nanoparticles created from ferric chloride solution using Camellia sinensis leaf extract as a reducing and stabilizing agent at room temperature. Characterization techniques, including XRD, FTIR, SEM–EDX, TEM, XPS, and UV–Vis spectroscopy, confirmed the successful integration of Fe0‐Fe2O3 into the polythiophene matrix. The nanocomposite demonstrated higher electrical conductivity compared to PTh alone, ranging from 20 S/cm at 313 K to 53 S/cm at 373 K. Magnetic studies indicated a saturation magnetization of 23.1 emu/g, lower than the 42.6 emu/g of Fe0‐Fe2O3 nanoparticles, attributed to the non‐magnetic nature of PTh. Under optimal conditions (4‐nitrobenzaldehyde [1 mmol], catalyst [0.04 g], and water [5 mL] in air), the catalyst achieved a 94% yield in the reduction of nitrobenzenes within 7 h, demonstrating broad applicability and retaining significant catalytic activity over six cycles. Furthermore, the PTh‐ Fe0‐Fe2O3 nanocomposite exhibited notable methanol gas sensing capabilities, with a sensitivity of 52.6 at 200‐ppm methanol. The sensor exhibited a response time of 60 s and a recovery time of 80 s, attributed to its n‐type semiconductor characteristics and abundant oxidative‐reductive sites. Computational studies supported the methanol sensing mechanism, highlighting significant O… S interactions and stable non‐covalent interactions between methanol and the nanocomposite. This study is the first to introduce a novel magnetic nanocatalyst for the cost‐effective and eco‐friendly reduction of nitroarenes, while also demonstrating its applicability in gas sensing. The research highlights an environmentally sustainable synthesis process and enhanced material properties, showcasing the nanocatalyst's potential for diverse applications.