Novel insights on the Pd speciation in Pd/SSZ-13 and on the role of H2O in the Pd reduction by CO.

Pd speciation induced by the combined effect of CO and water on Pd/SSZ-13 samples prepared by both impregnation and ion exchange was examined by FT-IR spectroscopy of CO adsorbed at room temperature and at liquid nitrogen temperature on anhydrous and hydrated samples. Starting from the literature findings related to the CO reducing effect on Pd cations, the present work gives precise spectroscopic evidences on how water is necessary in this process not only for compensating with H+ the zeolite exchange sites set free by Pd reduction, but also for mobilizing isolated Pd2+/Pd+ cations and making possible the reduction reactions. The aggregation of some Pd+ sites, just formed by the reduction and mobilized by the hydration, gives rise to the formation of Pd2O particles. Also, Pd0(100) sites are observed with CO on hydrated sample, formed by the aggregation and reduction of isolated Pd cations. Moreover, Pd0(111) sites are formed on the surface of PdOx particles during CO outgassing. The observation of the combined effect of water and CO allowed to define assignments of IR bands related to carbonyls of Pd in different oxidation states and coordination degrees.

Ammonothermal Synthesis of Luminescent Imidonitridophosphate Ba4P4N8(NH)2:Eu2.

The structural variability of a compound class is an important criterion for the research into phosphor host lattices for phosphor-converted light-emitting diodes (pc-LEDs). Especially, nitridophosphates and the related class of imidonitridophosphates are promising candidates. Recently, the ammonothermal approach has opened a systematic access to this substance class with larger sample quantities. We present the successful ammonothermal synthesis of the imidonitridophosphate Ba4P4N8(NH)2:Eu2+. Its crystal structure is solved by X-ray diffraction and it crystallizes in space group Cc (no. 9) with lattice parameters a = 12.5250(3), b = 12.5566(4), c = 7.3882(2) Å and ß = 102.9793(10)°. For the first time, adamantane-type (imido)nitridophosphate anions [P4N8(NH)2]8- are observed next to metal ions other than alkali metals in a compound. The presence of imide groups in the structure and the identification of preferred positions for the hydrogen atoms are performed using a combination of quantum chemical calculations, Fourier-transform infrared, and solid-state NMR spectroscopy. Eu2+ doped samples exhibit cyan emission (λmax = 498 nm, fwhm = 50 nm/1981 cm-1) when excited with ultraviolet light with an impressive internal quantum efficiency (IQE) of 41 %, which represents the first benchmark for imidonitridophosphates and is promising for potential industrial application of this compound class.

Formation of Paraldehyde (C6H12O3) in Interstellar Analog Ices of Acetaldehyde Exposed to Ionizing Radiation.

Acetaldehyde (CH3CHO) plays a crucial role in the synthesis of prebiotic molecules such as amino acids, sugars, and sugar-related compounds, and in the progress of chain reaction polymerization in deep space. Here, we report the first formation of the cyclic acetaldehyde trimer - paraldehyde (C6H12O3) - in low-temperature interstellar analog ices exposed to energetic irradiation as proxies of galactic cosmic rays (GCRs). Utilizing vacuum ultraviolet photoionization reflectron time-of-flight mass spectrometry and isotopic substitution experiments, paraldehyde was identified in the gas phase during the temperature-programmed desorption of the irradiated acetaldehyde ices based on the calculated adiabatic ionization energies and isomer-specific dissociative fragmentation patterns upon photoionization. As acetaldehyde is ubiquitous throughout the interstellar medium and has been tentatively identified in interstellar ices, paraldehyde could have formed in acetaldehyde-containing ices in a cold molecular cloud and is an excellent candidate for gas-phase observation in star-forming regions via radio telescopes. The identification of paraldehyde in the gas phase from the processed acetaldehyde ices advances our understanding of how complex organic molecules can be synthesized through polymerization reactions in extraterrestrial ices exposed to GCRs.

Synthesis, Structure, and Properties of a Copper(II) Binuclear Complex Based on Trifluoromethyl Containing Bis(pyrazolyl)hydrazone.

A new complex of copper(II) with methyl-5-(trifluoromethyl)pyrazol-3-yl-ketazine (H2L) was synthesized with the composition [Cu2L2]∙C2H5OH (1). Recrystallization of the sample from DMSO yielded a single crystal of the composition [Cu2L2((CH3)2SO)] (2). The coordination compounds were studied by single-crystal X-ray diffraction analysis, IR spectroscopy, and static magnetic susceptibility method. The data obtained indicate that the polydentate ligand is coordinated by both acyclic nitrogen and heterocyclic nitrogen atoms. The cytotoxic activity of the ligand and complex 1 was investigated on human cell lines MCF7 (breast adenocarcinoma), Hep2 (laryngeal carcinoma), A549 (lung carcinoma), HepG2 (hepatocellular carcinoma), and MRC5 (non-tumor lung fibroblasts). The complex was shown to have a pronounced dose-dependent cytotoxicity towards these cell lines with LC50 values in the range of 0.18-4.03 µM.

Investigation of the Structural Changes in Silk Due to Tin Weighting.

In the 19th century, the weighting of silk with metal salts, such as tin, was a common practice to enhance certain properties of silk fabrics and compensate for the weight loss incurred during the degumming process. This technique induces both physical and chemical modifications to the fibres, contributing to their long-term degradation, which requires thorough investigation. This study aims to examine the structural changes in silk fibres caused by the accumulation of metal salts from the tin-weighting process, using mock-up samples prepared through successive loading with weighting agents using a traditional tin-phosphate treatment method. Unweighted and tin-weighted silk samples were compared using scanning electron (SEM) micrographs, which presented the dispersed nanoparticles on the fibres, while through energy-dispersive X-ray spectroscopy (EDS) elemental mapping, the presence and uniform distribution of the weighting agents were confirmed. Fourier-transform infrared spectroscopy (FTIR) analysis revealed structural changes in tin-weighted silk samples compared to untreated ones, including shifts in amide bands, altered water/hydroxyl and skeletal stretching regions, and increased skeletal band intensities suggesting modifications in hydrogen bonding, ß-sheet content, and structural disorder without significantly impacting the overall crystallinity index. X-ray diffraction (XRD) analysis of both pristine and tin-weighted silk samples revealed significant alterations, predominantly in the amorphous regions of the silk upon weighting. These structural changes were further examined using small-angle X-ray scattering (SAXS) and small- and wide-angle X-ray scattering (SWAXS), which provided detailed insights into modifications occurring at the nanometre scale. The analyses suggested disruptions in ß-sheet crystals and intermolecular packing, especially in the amorphous regions, with increasing amounts of tin-weighting. Contact angle analysis (CA) revealed that the tin-phosphate-weighting process significantly impacted silk surface properties, transforming it from moderately hydrophobic to highly hydrophilic. These changes indicate that the incorporation of tin-phosphate nanoparticles on and within silk fibres could restrict the flexibility of polymer chains, impacting the physical properties and potentially the degradation behaviour of silk textiles. By studying these structural changes, we aim to deepen our understanding of how tin-weighting impacts silk fibre structure, contributing valuable insights into the longevity, conservation, and preservation strategies of silk textiles in the context of cultural heritage.

Physicochemical Characterization and Antimicrobial Properties of Lanthanide Nitrates in Dilute Aqueous Solutions.

This work presents the results of studying dilute aqueous solutions of commercial Ln(NO3)3 · xH2O salts with Ln = Ce-Lu using X-ray diffraction (XRD), IR spectroscopy, X-ray absorption spectroscopy (XAS: EXAFS/XANES), and pH measurements. As a reference point, XRD and XAS measurements for characterized Ln(NO3)3 · xH2O microcrystalline powder samples were performed. The local structure of Ln-nitrate complexes in 20 mM Ln(NO3)3 · xH2O aqueous solution was studied under total external reflection conditions and EXAFS geometry was applied to obtain high-quality EXAFS data for solutions with low concentrations of Ln3+ ions. Results obtained by EXAFS spectroscopy showed significant contraction of the first coordination sphere during the dissolution process for metal ions located in the middle of the lanthanide series. It was established that in Ln(NO3)3 · xH2O solutions with Ln = Ce, Sm, Gd, Yb (c = 134, 100, 50 and 20 mM) there are coordinated and, to a greater extent, non-coordinated nitrate groups with bidentate and predominantly monodentate bonds with Ln ions, the number of which increases upon transition from cerium to ytterbium. For the first time, the antibacterial and antifungal activity of Ln(NO3)3 · xH2O Ln = Ce, Sm, Gd, Tb, Yb solutions with different concentrations and pH was presented. Cross-relationships between the concentration of solutions and antimicrobial activity with the type of Ln = Ce, Sm, Gd, Tb, Yb were established, as well as the absence of biocidal properties of solutions with a concentration of 20 mM, except for Ln = Yb. The important role of experimental conditions in obtaining and interpreting the results was noted.

Expanding the scope of resonance Raman spectroscopy in hydrogenase research: New observable states and reporter vibrations.

Oxygen-tolerant [NiFe] hydrogenases are valuable blueprints for the activation and evolution of molecular hydrogen under application-relevant conditions. Vibrational spectroscopic techniques play a key role in the investigation of these metalloenzymes. For instance, resonance Raman spectroscopy has been introduced as a site-selective approach for probing metal-ligand coordinates of the [NiFe] active site and FeS clusters. Despite its success, this approach is still challenged by a limited number of detectable active-site states - due to missing resonance enhancement or intrinsic light sensitivity - and difficulties in their assignment. Utilizing two oxygen-tolerant [NiFe] hydrogenases as model systems, we illustrate how these challenges can be met by extending excitation and detection wavelength regimes in resonance Raman spectroscopic studies. Specifically, we observe that this technique does not only probe low-frequency metal-ligand vibrations but also high-frequency intra-ligand modes of the diatomic CO/CN- ligands at the active site of [NiFe] hydrogenases. These reporter vibrations are routinely probed by infrared absorption spectroscopy, so that direct comparison of spectra from both techniques allows an unambiguous assignment of states detected by resonance Raman spectroscopy. Moreover, we find that a previously undetected state featuring a bridging hydroxo ligand between Ni and Fe can be probed using higher excitation wavelengths, as photoconversion occurring at lower wavelengths is avoided. In summary, this study expands the applicability of resonance Raman spectroscopy to hydrogenases and other complex metalloenzymes by introducing new strategies for probing and assigning redox-structural states of the active site.

Room-Temperature Single-Molecule Infrared Imaging and Spectroscopy through Bond-Selective Fluorescence.

Infrared (IR) spectroscopy stands as a workhorse for exploring bond vibrations, offering a wealth of chemical insights across diverse frontiers. With increasing focus on the regime of single molecules, obtaining IR-sensitive information from individual molecules at room temperature would provide essential information about unknown molecular properties. Here, we leverage bond-selective fluorescence microscopy, facilitated by narrowband picosecond mid-IR and near-IR double-resonance excitation, for high-throughput mid-IR structural probing of single molecules. We robustly capture single-molecule images and analyze the combined polarization dependence, vibrational peaks, linewidths, and lifetimes of probe molecules with representative scaffolds. From bulk to single molecules, we find that vibrational lifetimes remain consistent, while linewidths are narrowed by approximately twofold and anisotropy becomes more pronounced. Additionally, unexpected peak shifts from single molecules were observed, attributed to the generation of new modes due to previously unexplored dimerization, supported by quantum chemistry calculations. These findings underscore the importance of infrared analysis on individual single molecules in ambient environments, offering molecular information crucial for functional imaging and the investigation of the fundamental properties and utilities of luminescent molecules.

Structure and Intercalation of Cysteine-Asparagine-Serine Peptide into Montmorillonite as an Anti-Inflammatory Agent Preparation-A DFT Study.

Peptides are receiving significant attention in pharmaceutical sciences due to their applications as anti-inflammatory drugs; however, many aspects of their interactions and mechanisms at the molecular level are not well-known. This work explores the molecular structure of two peptides-(i) cysteine (Cys)-asparagine (Asn)-serine (Ser) (CNS) as a molecule in the gas phase and solvated in water in zwitterion form, and (ii) the crystal structure of the dipeptide serine-asparagine (SN), a reliable peptide indication whose experimental cell parameters are well known. A search was performed by means of atomistic calculations based on density functional theory (DFT). These calculations matched the experimental crystal structure of SN, validating the CNS results and useful for assignments of our experimental spectroscopic IR bands. Our calculations also explore the intercalation of CNS into the interlayer space of montmorillonite (MNT). Our quantum mechanical calculations show that the conformations of these peptides change significantly during intercalation into the confined interlayer space of MNT. This intercalation is energetically favorable, indicating that this process can be a useful preparation for therapeutic anti-inflammatory applications and showing high stability and controlled release processes.

Conformational Changes in DNA and Protein Biomolecules in Pathogenesis of Ischemic Stroke.

Conformational changes in DNA and protein biomolecules were studied in ischemic stroke (IS) cases varying severity by Raman spectroscopy. The conformational structure of hematoporphyrin was found to change in IS patients, leading to a higher (I1355/I1550)/(I1375/I1580) ratio (hemoglobin affinity of for ligands) and an increase in I1375/I1172 (a change in pyrrole conformation). Changes in genomic DNA spectra were observed at frequencies caused by stretching vibrations of primary amines (3400 cm-1), secondary amines and hydroxyls involved in hydrogen bonding (3100 cm-1), and CH2 groups of sugar phosphates (2900 cm-1) and vibrations of vibrational bonds between nitrogenous bases and sugars (1400 cm-1). The significant changes observed in genomic DNA and hemoglobin spectra were assumed to indicate conformational rearrangements of the molecules in IS. Severe IS was associated with maximum changes in DNA and hemoglobin spectra.

The Invisible Fraction within Melanin Capable of Absorbing UV Light and with Fluorescent Properties: Is It Lacking Consideration?

Expanding on earlier observations, we show that many melanin materials, in vitro synthesized from a wide range of precursors, can be fractionated into a dark-colored precipitate and a near-colorless, dispersible fraction. The dispersible fractions exhibited absorbance in the UVA and UVB range of the electromagnetic spectrum, but none in the visible range. In addition, fluorescent properties were associated with all dispersible fractions obtained. FT-IR spectroscopic analyses were performed to compare both types of fractions. Overall, it appears that some of the properties associated with melanin (UV absorbance, fluorescence) may not necessarily reside in the dark-colored portion of melanin, but in a colorless fraction of the material. It remains to be seen whether any of these in vitro observations have any relevance in vivo. However, we raise the possibility that the presence of a colorless fraction within melanin materials and their associated properties may have received inadequate attention. Given the important association between melanin, UV protection, and skin cancer, it is worthwhile to consider this additional aspect of melanin chemistry.

Optimized infrared spectrum of ( H 2 O ) m : ( H C N ) n $$ {\left({H}_2O\right)}_m:{(HCN)}_n $$ mixtures.

Using density functional theory at D3-B3LYP/aug-cc-pVDZ level combined with the conductor-like polarizable continuum model (CPCM) solvent model, a study of the IR spectrum of H 2 O $$ {\mathrm{H}}_2\mathrm{O} $$ :HCN mixtures is reported. The CPCM solvent effect notably enhances the accuracy of the IR spectra compared to gas-phase calculations, while the dielectric constant value has minimum impact on the final spectrum. An optimized methodology is suggested that effectively minimizes the root mean square deviation between theoretical and experimental data. This novel approach not only enhances the quality of the final IR spectra but also captures relevant spectral features, highlighting its potential to decipher molecular interactions in such intricate mixtures.

Insights on early response to acute heat shock of bovine mammary epithelial cells through a multimethod approach.

Heat stress is a significant challenge in dairy cattle herds, affecting milk production and quality, and generating important changes at the cellular level. Most in vitro research on heat shock (HS) effects on dairy cow mammary cells was focused on medium-long-term effects. In recent years, Fourier transform-infrared (FT-IR) micro-spectroscopy has been increasingly used to study the effects of several external stresses on different cell lines, down to the level of single cellular components, such as DNA/RNA, lipids, and proteins. In this study, the possible changes at the biochemical and molecular level induced by acute (30 min-2 h) HS in bovine mammary epithelial (BME-UV1) cells were investigated. The cells were exposed to different temperatures, thermoneutral (TN, 37 °C) and HS (42 °C), and FT-IR spectra were acquired to analyse the effects of HS on biochemical characteristics of BME-UV1 cellular components (proteins, lipids, and DNA/RNA). Moreover, cell viability assay, reactive oxygen species production, and mRNA expression of heat shock proteins (HSPA1A, HSP90AA1, GRP78, GRP94) and antioxidant genes (SOD1, SOD2) by RT-qPCR were also analysed. The FT-IR results showed a change already at 30 min of HS exposure, in the content of long-chain fatty acids, which probably acted as a response to a modification of membrane fluidity in HS cells compared with TN cells. After 2 h of HS exposure, modification of DNA/RNA activity and accumulation of aggregated proteins was highlighted in HS cells. The gene expression analyses showed the overexpression of HSPA1A and HSP90AA1 starting from 30 min up to 2 h in HS cells compared with TN cells. At 2 h of HS exposure, also the overexpression of GRP94 was observed in HS cells. Acute HS did not affect cell viability, reactive oxygen species level, and SOD1 and SOD2 gene expression of BME-UV1 cells. According to the results obtained, cells initiate early defence mechanisms in case of acute HS and probably this efficient response capacity may be decisive for tolerance to heat stress of dairy cattle.

Analysis of the Adsorption Behavior of Phenanthrene on Microplastics Based on Two-Dimensional Correlation Spectroscopy.

Microplastics (MPs), an emerging pollutant, widely co-occur with polycyclic aromatic hydrocarbons (PAHs) in the environment. Therefore, the interaction between MPs and PAHs has been the focus of much attention in recent years. In this study, three types of MPs, i.e., polypropylene, polystyrene, and poly(vinyl chloride), with the same main chain were selected as the adsorbents, with phenanthrene (PHE) as the representative PAHs. The adsorption mechanisms were explored from the perspective of the molecular spectral level using a combination of Fourier transform infrared spectroscopy (FT-IR) with a two-dimensional correlation technique. The adsorption kinetics results showed that the adsorption of PHE on the three MPs was dominated by chemisorption. However, the FT-IR analysis results indicated that no new covalent bond was created during the adsorption process. Based on the above research, a generalized two-dimensional (2D) correlation spectral technique was employed to investigate the sequence of functional group changes during the adsorption process for different MPs. Furthermore, the hybrid 2D correlation spectral technique explored the effect of side groups attached to the main chain molecules of MPs on adsorption. The results showed that for all three MPs, the functional groups in the side chain have a higher affinity for PHE, which is due to their higher hydrophobicity. This study provides a feasible way to analyze the adsorption of pollutants on MPs, and the results are important for understanding the adsorption interaction between PAHs and MPs in the aquatic environment.

Exploration of Sargassum wightii: Extraction, Phytochemical Analysis, and Antioxidant Potential of Polyphenol.

Background The marine environment, with its rich biodiversity and nutrient-dense ecosystems, offers immense potential for discovering novel pharmaceutical products. Sargassum wightii is a type of brown seaweed that is particularly abundant in sulfated polysaccharides and polyphenolic compounds. These compounds are renowned for their wide range of biological activities. The exploration of such marine resources is crucial for identifying new compounds that can be harnessed for pharmaceutical and nutraceutical applications. Aims and objectives The primary aim of this study is to explore the bioactive compounds present in S. wightii, with a specific focus on its polyphenolic content. Additionally, the study seeks to evaluate the antioxidant properties of the compound. By doing so, the research aims to contribute to the growing body of knowledge on marine bioresources and their potential health benefits. Methods S. wightii samples were collected from the Mandapam coastal region in Rameshwaram, India. The cleaned seaweed was transported to the laboratory, where it was further washed, shade-dried, and ground into a fine powder. The powdered seaweed was then subjected to extraction using four different solvents: n-hexane, dichloromethane, ethyl acetate, and methanol. Phytochemical analyses were conducted on these extracts to identify the presence of various bioactive compounds. The total phenolic content of the extracts was determined, and antioxidant activity was assessed using the phosphomolybdenum method. Functional groups present in the extracts were identified using Fourier Transform Infrared (FT-IR) spectroscopy. Results Among the solvents used, the methanol extract yielded the highest amount of crude extract. Phytochemical analysis revealed a variety of bioactive compounds, with the methanol extract showing a notable presence of polyphenols. The total phenolic content was measured at 1.25 ± 0.6 mg gallic acid equivalence (GAE)/g of extract. The antioxidant activity, assessed through the phosphomolybdenum method, demonstrated significant free radical scavenging capabilities with an IC50 (half maximal inhibitory concentration) value of 68.23 ± 3.5 µg/mL. FT-IR spectroscopy confirmed the presence of functional groups characteristic of polyphenols and other bioactive compounds. Conclusion The study highlights the significant potential of S. wightii as a source of bioactive compounds with substantial antioxidant properties. These findings emphasize the importance of marine algae in the development of pharmaceutical and nutraceutical products, showcasing S. wightii's promising role in health-related applications.

Photochemical Generation and Characterization of C-Aminophenyl-Nitrilimines: Insights on Their Bond-Shift Isomers by Matrix-Isolation IR Spectroscopy and Density Functional Theory Calculations.

The intriguing ability of C-phenyl-nitrilimine to co-exist as allenic and propargylic bond-shift isomers motivated us to investigate how substituents in the phenyl ring influence this behavior. Building on our previous work on the meta- and para-OH substitution, here we extended this investigation to explore the effect of the NH2 substitution. For this purpose, C-(4-aminophenyl)- and C-(3-aminophenyl)-nitrilimines were photogenerated in an argon matrix at 15 K by narrowband UV-light irradiation (λ = 230 nm) of 5-(4-aminophenyl)- and 5-(3-aminophenyl)-tetrazole, respectively. The produced nitrilimines were further photoisomerized to carbodiimides via 1H-diazirines by irradiations at longer wavelengths (λ = 380 or 330 nm). Combining IR spectroscopic measurements and DFT calculations, it was found that the para-NH2-substituted nitrilimine exists as a single isomeric structure with a predominant allenic character. In contrast, the meta-NH2-substituted nitrilimine co-exists as two bond-shift isomers characterized by propargylic and allenic structures. To gain further understanding of the effects of phenyl substitution on the bond-shift isomerism of the nitrilimine fragment, we compared geometric and charge distribution data derived from theoretical calculations performed for C-phenyl-nitrilimine with those performed for the derivatives resulting from NH2 (electron-donating group) and NO2 (electron-withdrawing group) phenyl substitutions.

Quantitative modelling of Plato and total flavonoids in Qingke wort at mashing and boiling stages based on FT-IR combined with deep learning and chemometrics.

Craft beer brewers need to learn process control strategies from traditional industrial production to ensure the consistent quality of the finished product. In this study, FT-IR combined with deep learning was used for the first time to model and analyze the Plato degree and total flavonoid content of Qingke beer during the mashing and boiling stages and to compare the effectiveness with traditional chemometrics methods. Two deep learning neural networks were designed, the effect of variable input methods on the effectiveness of the models was discussed. The experimental results showed that the CARS-LSTM model had the best predictive performance, not only as the best quantitative model for Plato in the mashing (R2p = 0.9368) and boiling (R2p = 0.9398) phases but also as the best model for TFC in the boiling phase (R2p = 0.9154). This study demonstrates the great potential of deep learning and provides a new approach to quality control analysis in beer brewing.

Manufacturing Single-Atom Alloy Catalysts for Selective CO2 Hydrogenation via Refinement of Isolated-Alloy-Islands.

Single-atom alloy (SAA) catalysts exhibit huge potential in heterogeneous catalysis. Manufacturing SAAs requires complex and expensive synthesis methods to precisely control the atomic scale dispersion to form diluted alloys with less active sites and easy sintering of host metal, which is still in the early stages of development.  Here, we address these limitations with a straightforward strategy from a brand-new perspective involving the 'islanding effect' for manufacturing SAAs without dilution: homogeneous RuNi alloys were continuously refined to highly dispersed alloy-islands (~ 1 nm) with completely single-atom sites where the relative metal loading was as high as 40%. Characterized by advanced atomic-resolution techniques, single Ru atoms were bonded with Ni as SAAs with extraordinary long-term stability and no sintering of the host metal. The SAAs exhibited 100% CO selectivity, over 55 times reverse water-gas shift (RWGS) rate than the alloys with Ru cluster sites, and over 3-4 times higher than SAAs by the dilution strategy. This study reports a one-step manufacturing strategy for SAA's using the wetness impregnation method with durable high atomic efficiency and holds promise for large-scale industrial applications.

Antibacterial Efficacy and Characterization of Silver Nanoparticles Synthesized via Methanolic Extract of Fomes fomentarius L. Fr.

Green synthesis employs environmentally friendly, biodegradable substances for the production of nanomaterials. This study aims to develop an innovative method for synthesizing silver nanoparticles (AgNPs) using a methanolic extract of Fomes fomentarius L. Fr. as the reducing agent and to assess the potential antibacterial properties of the resulting nanoparticles. The successful synthesis of AgNPs was confirmed through characterization techniques such as UV-visible (UV-Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FT-IR), and powder X-ray diffraction (PXRD). The UV-Vis analysis revealed an absorption peak at 423 nm, while FT-IR identified key phytochemical compounds involved in the reduction process. PXRD analysis indicated a face-centered cubic (fcc) structure with prominent peaks observed at 2θ = 38°, 44.6°, 64.6°, and 78°, confirming the crystalline nature of the AgNPs, with a crystallite diameter of approximately 24 nm, consistent with TEM analysis. The synthesized AgNPs demonstrated significant antibacterial activity, particularly against S. aureus, with higher efficacy against gram-positive bacteria.

Doxorubicin as a Drug Repurposing for Disruption of α-Chymotrypsinogen-A Aggregates.

Protein conformation is affected by interaction of several small molecules resulting either stabilization or disruption depending on the nature of the molecules. In our earlier communication, Hg2+ was known to disrupt the native structure of α-Cgn A leading to aggregation (Ansari, N.K., Rais, A. & Naeem, A. Methotrexate for Drug Repurposing as an Anti-Aggregatory Agent to Mercuric Treated α-Chymotrypsinogen-A. Protein J (2024). https://doi.org/10.1007/s10930-024-10187-z ). Accumulation of ß-rich aggregates in the living system is found to be linked with copious number of disorders. Here, we have investigated the effect of varying concentration of doxorubicin (DOX) i.e. 0-100 µM on the preformed aggregates of α-Cgn A upon incubation with 120 µM Hg2+. The decrease in the intrinsic fluorescence and enzyme activity with respect to increase in the Hg2+ concentration substantiate the formation of aggregates. The DOX showed the dose dependent decrease in the ThT fluorescence, turbidity and RLS measurements endorsing the dissolution of aggregates which were consistent with red shift in ANS, confirming the breakdown of aggregates. The α-Cgn A has 30% α-helical content which decreases to 3% in presence of Hg2+. DOX increased the α-helicity to 28% confirming its anti-aggregatory potential. The SEM validates the formation of aggregates with Hg2+ and their dissolution upon incubation with the DOX. Hemolysis assay checked the cytotoxicity of α-Cgn A aggregates. Docking revealed that the DOX interacted Lys203, Cys201, Cys136, Ser159, Leu10, Trp207, Val137 and Thr134 of α-Cgn A through hydrophobic interactions and Gly133, Thr135 and Lys202 forms hydrogen bonds.