UV Spectra Research Articles

Characterization of Low-Molecular-Weight Dissolved Organic Matter Using Optional Dialysis and Orbitrap Mass Spectrometry.

Low-molecular-weight (LMW, <1000 Da) dissolved organic matter (DOM) plays a significant role in metal/organic pollutant complexation, as well as photochemical/microbiological processes in freshwater ecosystems. The micro size and high reactivity of LMW-DOM hinder its precise characterization. In this study, Suwannee River fulvic acid (SRFA), a commonly used reference material for aquatic DOM, was applied to examine the optical features and molecular composition of LMW-DOM by combining membrane separation, ultraviolet-visible absorption and Orbitrap mass spectrometry (MS) characterization. The 100-500 Da molecular weight cut-off (MWCO) membrane had a better performance in regard to separating the tested LMW-DOM relative to the 500-1000 Da MWCO membrane. The ultraviolet-visible absorbance decreased dramatically for the retentates, whereas it increased for the dialysates. Specifically, carbohydrates, lipids and peptides exhibited high selectivity to the 100-500 Da MWCO membrane in early dialysis. Lignins, tannins and condensed aromatic molecules displayed high permeability to the 500-1000 Da MWCO membrane in late dialysis. Overall, the retentates were dominated by aromatic rings and phenolic hydroxyls with high O/Cwa (weighted average of O/C) and low H/Cwa. Conversely, such dialysates had numerous aliphatic chains with high H/Cwa and low O/Cwa compared to SRFA. In particular, LMW-DOM below 200 Da was identified by Orbitrap MS. This work provides an operational program for identifying LMW-DOM based on the SRFA standard and MS analysis.

Aggregation of N-Heteropolycyclic Aromatic Molecules: The Acridine Dimer and Trimer.

Polycyclic aromatic hydrocarbons and their nitrogen-substituted analogues are of great interest for various applications in organic electronics. The performance of such devices is determined not only by the properties of the single molecules, but also by the structure of their aggregates, which often form via self-aggregation. Gaining insight into such aggregation processes is a challenging task, but crucial for a fine-tuning of the materials properties. In this work, an efficient approach for the generation and characterisation of aggregates is described, based on matrix-isolation experiments and quantum-chemical calculations. This approach is exemplified for aggregation of acridine. The acridine dimer and trimer are thoroughly analysed on the basis of experimental and calculated UV and IR absorption spectra, which agree well with each other. Thereby a novel structure of the acridine dimer is found, which disagrees with a previously reported one. The calculations also show the changes from excitonic coupling towards orbital interactions between two molecules with decreasing distance to each other. In addition, a structure of the trimer is determined. Finally, an outlook is given on how even higher aggregates can be made accessible through experiment.

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.

Broadband rapid-scanning phase-modulated Fourier transform electronic spectroscopy.

We present a phase-modulated approach for ultrabroadband Fourier transform electronic spectroscopy. To overcome the bandwidth limitations and spatial chirp introduced by acousto-optic modulators (AOMs), pulses from a 1 µm laser are modulated using AOMs prior to continuum generation. This phase modulation is transferred to the continuum generated in a yttrium aluminum garnet crystal. Separately generated phase-modulated continua in two arms of a Mach-Zehnder interferometer interfere with the difference of their modulation frequencies, enabling physical under-sampling of the signal and the suppression of low-frequency noise. By interferometrically tracking the relative time delay of the continua, we perform continuous, rapid-scanning Fourier transform electronic spectroscopy with a high signal-to-noise ratio and spectral resolution. As proof of principle, we measure the linear absorption and fluorescence excitation spectra of a laser dye and various biological samples.

Formulation and Evaluation of Albumin-Stabilized Silver Nanoparticles Loaded with Methotrexate: Anticancer Activity and DNA Binding Analysis with Molecular Modeling

Nano-metal technology has emerged recently as an exceptional biological targeted field with numerous advantages like small size and high surface charge. In this report, we described our research on the stabilization of prepared silver nanocores coated with bovine serum albumin and further loaded with methotrexate (MTX) drug. The prepared nanoparticles were characterized by using UV-Visible, X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and cyclic voltammetry (CV). The UV spectra of AgNP showed a prominent peak at 400 nm. The presence of MTX was confirmed by the FT-IR and EDX analysis. The AgNP-BSA-MTX particles resembled elliptical shape like structures in the SEM images. In-vitro drug release for free drug MTX occurred rapidly in a period of 12 hrs (85%), whereas a sustained release of MTX greater than 85% from the AgNP-BSA-MTX nanoparticles was observed for 48 hrs. The AgNP-BSA-MTX demonstrated a five-fold higher cytotoxic activity compared to free MTX drug alone against PC-3 cell lines, performed by the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay method. DNA binding studies were performed for the AgNP-BSA-MTX with calf thymus DNA (ct-DNA). In-silico studies were performed for MTX with DNA (Protein Data Bank ID-IZ3F) and a prominent interaction with the nucleotides was noted. Molecular Dynamics (MD) simulation studies were also performed for the docked MTX-DNA complex. The average of the Root mean square deviation (RMSD) values for the DNA backbone was calculated to be 5.71 ± 0.48 nm.

Mechanistic Insights into UV Spectral Changes of Pyruvic Acid and Pyruvate Part 1: Interaction with Water Molecules

We investigate how the UV spectra of pyruvic acid (PA) and pyruvate are impacted by interactions with water molecules. In particular, we would like to understand the mechanistic origin of the blue shift in the n →− π∗ transition. Pyruvic acid is the simplest α-keto organic acid and is common in the environment. We use density functional theory to optimize geometries to determine excitation energies and find that the excitation energies of the two main pyruvic acid conformers and pyruvate blue shift when interacting with 1 to 4 water molecules, both in vacuo and in a solvent. The excitation wavelength is blue-shifted by 0.9-9.2 nm when adding water molecules to the lowest energy conformer of PA. Calculations of the UV spectra of pyruvic acid (PA) and pyruvate are crucial for understanding the impact of the interactions with water molecules.

Evaluation of a rapid multi-attribute combinatorial high-throughput UV-Vis/DLS/SLS analytical platform for rAAV quantification and characterization

Recombinant adeno-associated virus (rAAV)-based gene therapies are expanding in their application. Despite progress in manufacturing, current analytical methods for product quantification and characterization remain largely unchanged. Although critical for product and process development, in-process testing, and batch release, current analytical methods are labor-intensive, costly, and hampered by extended turnaround times and low throughput. The field requires more efficient, cost-effective analytical techniques capable of handling large sample quantities to accelerate product and process development. Here, we evaluated Stunner from Unchained Labs for quantifying and characterizing rAAVs and compared it with established analytical methods. Stunner is a combinatorial analytic technology platform that interpolates ultraviolet-visible (UV-Vis) absorption with static and dynamic light scattering (SLS/DLS) analysis to determine capsid and genomic titer, empty and full capsid ratio, and assess vector size and polydispersity. The platform offers empirical measurements with minimal sample requirements. Upon testing hundreds of rAAV vectors, comprising various serotypes and transgenes, the data show a strong correlation with established analytical methods and exhibit high reproducibility and repeatability. Some analyses can be applied to in-process samples from different purification stages and processes, fulfilling the demand for rapid, high-throughput analysis during development. In sum, the pipeline presented streamlines small- and large-batch analytics.

Vibrational assignments of monohydrate dimer of violuric acid by using FT-IR, FT-Raman and UV spectra and DFT calculations in different media

Experimental FT-IR, FT-Raman and UV spectra have been combined with hybrid B3LYP/6–311++G** calculations and the scaled quantum mechanical force field (SQMFF) methodology to study structural and vibrational properties of monohydrated dimer (MD) of violuric acid in gas and aqueous media. Complete vibrational assignments and its scaled force constants are reported together with the corresponding to anhydrous and monohydrate monomer. From four anhydrous C1, C2, C3, C4 monomers, C4 is the most stable in both media. In solution, the initial structure of C2 change to the tautomeric species most stable C4. The MD reveals a higher solvation energy while natural bond orbital (NBO) and atoms in molecules (AIM) calculations support the higher stability of this species due to the six H bonds interactions and to its higher expansion of volume in solution. The MD is the most reactive species, as revealed by the lowest gap value and by high global electrophilicity and most negative global nucleophilicity indexes. Very good concordances are observed among the predicted IR, Raman, 13C NMR and UV spectra and the corresponding experimental ones. Comparisons of predicted 13C NMR and electronic spectra with the experimental one show that those three species of violuric acid could be present in aqueous solution. Similar f(νC=O) and f(νC-O) force constants for the three species are justified by the important delocalization of electrons evidenced in anhydrous and monohydrate species by NBO calculations.

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.

Influence of supramolecular self-assembly of oppositely charged Co- and Sn-porphyrins on the their spectral-luminescent properties in aqueous and aqueous micellar media of ionic surfactants

The processes of supramolecular self-assembly of Co(III)-meso-tetra-(4-trimethylammoniophenyl)porphyrin (CoP) and bis-(4-(1-imidazolyl)-phenol)-Sn(IV)-meso-tetra(4-sulfophenyl)porphyrin (SnP) were studied using electronic, steady-state and time-resolved fluorescence, one- and two-dimensional NMR spectroscopy in aqueous media. The main product of such interaction at a 2:1 M ratio of Co and Sn porphyrinates was found to be supramolecular porphyrin trimer CoP–SnP–CoP formed due to donor-acceptor, hydrogen and electrostatic interactions. The distinctive features of the resulting trimer are: significant distortion of the spatial structure of the Co-porphyrin fragments and strong quenching of the Sn-porphyrin macrocycles fluorescence (by 70 %). The distortion of the spatial structure of Co porphyrinates is in good agreement with the quantum chemical calculations as well as with the electronic and NMR spectroscopy data. Adding surfactants – both anionic (Cetyltrimethylammonium bromide - CTAB) and cationic (Sodium dodecyl sulfate - SDS) – even at concentrations below the critical micelle concentration (CMC) leads to the supramolecular trimer destruction. In solutions of ionic surfactants, supramolecular trimer destruction is caused by the interaction of either the peripheral macrocycles of the trimer (CoP) with SDS micelles (premicellar aggregates) or the central macrocycle (SnP) with CTAB micelles (premicellar aggregates). This process is prolonged and the rate of trimer destruction depends on the surfactant concentration. The sizes of the CTAB and SDS micelles solubilized with porphyrin molecules were established by dynamic light scattering. In general, surfactant additions lead to an increase in the SnP fluorescence at least due to the destruction of the supramolecular self-assembly, as well as due to the changes in the state of its microenvironment.

Sequence-Dependent Surface Coverage of ssDNA Coatings on Single-Wall Carbon Nanotubes.

A combination of experimental measurements and molecular dynamics (MD) simulations was used to investigate how the surfaces of single-wall carbon nanotubes (SWCNTs) are covered by adsorbed ssDNA oligos with different base compositions and lengths. By analyzing the UV absorption spectra of ssDNA-coated SWCNTs before and after coating displacement by a transparent surfactant, the mass ratios of adsorbed ssDNA to SWCNTs were determined for poly-T, poly-C, GT-containing, and AT-containing ssDNA oligos. Based on the measured mass ratios, it is estimated that an average of 20, 22, 26, or 32 carbon atoms are covered by one adsorbed thymine, cytosine, adenine, or guanine nucleotide, respectively. In addition, the UV spectra revealed electronic interactions of varying strengths between the nucleobase aromatic rings and the nanotube π-systems. Short poly-T DNA oligos show stronger π-π stacking interactions with SWCNT surfaces than do short poly-C DNA oligos, whereas both long poly-C and poly-T DNA oligos show strong interactions. These experiments were complemented by MD computations on simulated systems that were constrained to match the measured ssDNA/SWCNT mass ratios. The surface coverages computed from the MD results varied with oligo composition in a pattern that correlates higher measured yields of nanotube fluorescence with greater surface coverage.

Acriflavine Is More than It Seems: Resolving Optical Properties of Multiple Isomeric Constituents at 5 K.

Ion mobility spectrometry at room temperature was combined with vibrationally resolved electronic spectroscopy of mass-selected ions at 5 K to study the well-known cationic fluorophore acriflavine. One- and two-color photodepletion action spectra recorded in gas-phase (by helium tagging) as well as dispersed fluorescence spectra obtained in neon matrix (after soft-landing deposition) indicate that the primary cation mass electrosprayed from solution comprises two isomers with different optical properties. Theory at the TD-DFT level allowed full spectral assignment. The results have implications for the preparation of novel thin film photonic materials by low-energy ion beam deposition.

Synergistic Influence of Doping and Co‐Doping of Trivalent Ions (La+3 and Al+3) on YFeO3 Nanomaterials

Herein, the structural, optical, and magnetic properties of Y0.85La0.15FexAlyO3: (x; y) where x = 1; y = 0, x = 0.975; y = 0.025, x = 0.95; y = 0.05, and x = 0.9; y = 0.1 nanomaterials obtained from sol–gel method are reported. The X‐ray powder diffraction (XRD) for the structural characterization, scanning electron microscopy for crystallite size estimation, ultraviolet–visible absorption for optical studies, and vibrating‐sample magnetometer for magnetic studies are used in this investigation. An increase of orthorhombic crystal structure with an increase of Al content in the sample is observed from XRD studies. The existence of all the elements present in the samples is observed from energy‐dispersive X‐ray spectroscopy. The optical bandgap increases from 2.04 to 2.10 eV with an increase of Al concentration from 0 to 0.05. The observed magnetization value is 3.14 emu g−1 for y = 0.05, which is higher than y = 0 (2.11 emu g−1) and y = 0.024 (2.58 emu g−1). In summary, the obtained result (x = 0.95; y = 0.05) can be useful for different magnetic‐based applications.

Visual fluorescence detection kit for Cr (VI) based on biological matrix-derived carbon dots and assisted for AA

In this study, a novel green donkey-hide gelatin carbon dots (D-CDs) were synthesized by hydrothermal method and a portable detector based on Cr (VI) fluorescent test strips was prepared. The synthesized D-CDs exhibited bright blue fluorescence which was used for the detection of Cr (VI) and ascorbic acid (AA). It still exhibited high sensitivity and acceptable selectivity under high concentration of other interfering ions. The morphology and elemental characteristics of D-CDs were characterized. Meanwhile, the “on-off” quenching mechanism of Cr (VI) on D-CDs was studied by ultraviolet-visible absorption spectra, fourier transform infrared spectroscopy and fluorescence spectra. Then a D-CDs/Cr (VI) fluorescence sensing platform was constructed, and reopened by AA, thus eliciting an “on-off-on” fluorescence reaction. Under the optimal conditions, the fluorescence intensity was quenched significantly with the increase of Cr (VI) concentration and restored by the good reducibility of ascorbic acid (AA), with the linear ranges of 0.5–400 μM and 1–400 μM, respectively. The detection limits of Cr (VI) and AA can be as low as 0.08 μM and 0.14 μM. Consequently, it has low toxicity and can be successfully used as a fluorescent probe to determine Cr (VI) in river water and AA in fruits with satisfactory results. It not only lays a foundation for the development of fluorescence sensor in the field of environment and food, but also provides a good application prospect for its detection of heavy metal ions and AA.

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.

Ineffectiveness of carbapenems in real-world clinical practice according to therapeutic drug monitoring data and Roszdravnadzor AIS reports

Relevance. The use of carbapenems is associated with significant variability in pharmacokinetics/pharmacodynamics (FC/PD) parameters, particularly in critically ill patients. The combination of variability in these parameters and standardized dosing regimens can lead to irrational dosing, excessively high or low doses, and consequently less effective treatment and resistance. Optimal management of these factors is essential for combating the development of resistance, particularly for reserve antibiotics.The aim of this study was to evaluate the achievement of the target levels of carbapenems (imipenem/cilastatin) in plasma concentrations in patients with burn injury based on therapeutic drug monitoring and to analyze spontaneous reports registered in the AIS Roszdravnadzor database regarding the effectiveness of therapy.Methods. The analysis included patients receiving antibiotic therapy with imipenem/cilastatin in the burn unit for adults at the University Hospital of the Volga Region Research Medical University for burn trauma who were hospitalized from 01.03.2023 to 30.06.2023. The study was conducted without correcting the trade name of imipenem/cilastatin. Therapeutic drug monitoring was performed after the 4th administration of imipenem/cilastatin. Blood was drawn at 3 h (1st sample), 5 h (2nd sample), and 8 h (3rd sample) after infusion in a clotting activator tube. The analysis was performed using a liquid chromatograph "LC-20 Prominance" (Shimadzu, Japan) in reversed-phase mode with a matrix photodiode detector for UV and visible spectra. Data processing was performed using the LCsolution program. Spontaneous reports regarding the use of carbapenems recorded in the AIS of Roszdravnadzor from January 2020 to November 2023 were also analyzed as the object of the study.Results. The results of the study of carbapenems (imipenem/cilastatin) concentration level achievement in the plasma of patients with burn injury showed that the effective imipenem concentration exceeding the MPC value in relation to the isolated Gram-negative pathogen was found only in 1 out of 5 patients included in the study. Two patients showed dynamically changing IPC values during treatment, indicating the necessity of therapeutic drug monitoring, as well as the probability of failure to achieve target concentrations and optimal FC/FD values. In another two patients, imipenem concentrations were insufficient to maintain optimal FC/PD values, indicating that the antimicrobial regimen was ineffective. An analysis of spontaneous reports registered in the AIS of Roszdravnadzor regarding identified cases of the ineffectiveness of carbapenems (imipenem/cilastatin, meropenem) revealed 5,2% of reports regarding meropenem and 1.4% regarding imipenem/cilastatin in the total structure of reports.Conclusion. The implementation of therapeutic drug monitoring procedures can reduce therapy ineffectiveness and antibiotic resistance through personalized antimicrobial dosing.

Conductometric H2S Sensors Based on TiO2 Nanoparticles.

High-performance hydrogen sulfide (H2S) sensors are mandatory for many industrial applications. However, the development of H2S sensors still remains a challenge for researchers. In this work, we report the study of a TiO2-based conductometric sensor for H2S monitoring at low concentrations. TiO2 samples were first synthesized using the sol-gel route, annealed at different temperatures (400 and 600 °C), and thoroughly characterized to evaluate their morphological and microstructural properties. Scanning electronic microscopy, Raman scattering, X-ray diffraction, and FTIR spectroscopy have demonstrated the formation of clusters of pure anatase in the TiO2 phase. Increasing the calcination temperature to 600 °C enhanced TiO2 crystallinity and particle size (from 11 nm to 51 nm), accompanied by the transition to the rutile phase and a slight decrease in band gap (3.31 eV for 400 °C to 3.26 eV for 600 °C). Sensing tests demonstrate that TiO2 annealed at 400 °C displays good performances (sensor response Ra/Rg of ~3.3 at 2.5 ppm and fast response/recovery of 8 and 23 s, respectively) for the detection of H2S at low concentrations in air.

Multifunctional pectin and lignin-containing cellulose nanofiber films with improved UV resistance and mechanical properties

This study aimed to study the real-time interaction of apple pectin and LCNF using Quartz crystal microbalance with dissipation monitoring (QCM-D) to understand the compositional factors that influence their film formation and assess the impact of varying polymer ratios (0–100%) on the UV resistance, hydrophobicity, and mechanical properties of resulting composite films. Results revealed that apple pectin forms partially irreversible interaction with LCNF, evidenced by a frequency change of 14.9 Hz after the final rinsing stage. This finding was supported by FTIR of the composite films, demonstrated by a shift of the broader –OH stretching vibration at 3325 cm−1 to 3302 cm−1 due to the formation of strong hydrogen bonding. LCNF-based films (LCNF >50%) were less soluble in water compared to pectin-based films (pectin >50%) due to less permeable structure and hydrophobic lignin which interferes in hydrogen bonding with water. Pectin-based films displayed high transparency (%Transmittance >89% at 650 nm) and lower hydrophobicity. Due to the presence of lignin chromophores, the UV shielding property was the highest for LCNF-based films as it almost completely shielded the UV spectrum (%T ∼0 at 320 nm). The reinforcement provided by LCNF significantly enhanced the mechanical properties of the films. Consequently, this study offers valuable insights into the real-time interaction dynamics between apple pectin and LCNF, facilitating the development of biocomposite films with versatile properties that hold significant promise for a wide range of applications.

Metal-enhanced fluorescence (MEF) effect based on silver nanoparticles with different UV spectra on a surface carbon dot-based novel dry platform

In this work, to enhance the fluorescence quantum yield of carbon dots (CDs), a novel metal-enhanced fluorescence (MEF) structure was designed by decorating CDs on silver nanoparticle (AgNPs) film. The glass slide-AgNPs (GS-AgNPs) structure was fabricated using the electrostatic adsorption method, and the AgNPs-CDs structures were prepared by the direct drying method, which then formed the GS-AgNPs-CDs composite structure. In this structure, the MEF effect was found to be size dependent by changing the 5 types of AgNPs with different sizes. And the MEF effect also decreased as the distance between the AgNPs and CDs increased by using polyvinylpyrrolidone (PVP) to separate the AgNPs and CDs. This hybrid structure can be used as a fluorescence detection platform and the recorded fluorescence intensity of GS-AgNPs 428 nm-CDs achieved a maximum enhancement factor (EF) of 31.72. Considering the high enhancement factor, this system may become promising to find potential applications in biochemical assay fields.

Enhancing bacterial control and daylight-driven water remediation with chitosan-impregnated MoC nanosheets.

The functionalization of nanoparticles with 2D nanosheets is an effective approach to enhance their functional properties for pollutant removal. This research outlines the synthesis of a 2D-delaminated molybdenum carbide (MXene) chitosan nanocomposite (2D-d-Mo2CTx-Cs NC) with bacterial control and photocatalytic properties for dye adsorption. The nanocomposite includes Tx-surface terminating groups O, OH, and F. In this investigation, the composite was synthesized using the etching method and its formation was confirmed through UV spectra at 288nm. It was characterized through FTIR, XRD, Particle size, Zetapotential, FESEM, HRTEM, EDAX, and XPS analyses. FTIR spectral analysis of NC suggests that amines are formed through a Schiff base reaction between glutaraldehyde and Cs, or through the interaction of terminal aldehydes and carbonyl groups. The XRD analysis confirmed the crystalline structure of the composite. FESEM images revealed irregularly structured nanosheets (NSs) material in the prepared 2D-d-Mo2CTx-Cs NC samples. HRTEM images revealed 2D-d-Mo2CTx NSs impregnated onto Cs with an average size of 50nm, as confirmed by a particle size analyzer, with a zeta potential value of -15mV. Additionally, Mo, C, N, and O are the most significant elements present in the NC, as confirmed by EDAX and XPS analyses. Further, biocompatibility testing of 2D-d-Mo2CTx-Cs NC yielded positive results. Moreover, under sunlight, the composites effectively adsorbed methylene blue with a 90% adsorption capacity, as confirmed by kinetic studies. Furthermore, the synergistic effect of Cs and d-Mo2CTx NSs resulted in significant antibacterial (50-200µl of 1mg/ml) and antibiofilm activity (100µl of 1mg/ml) against pathogenic bacteria. Furthermore, this study represents the first report on the use of 2D-d-Mo2CTx-Cs NC for daylight-influenced photocatalytic applications with a bacteria-controlling effect.