UV-visible Spectroscopic Methods Research Articles

A novel and simple method based on the chemometric treatment of UV–visible spectra of acetonitrile extracts to detect plant-derived adulterants in saffron (Crocus sativus L.)

We developed a UV–visible spectroscopic method, inspired by ISO-3632 normative conventionally adopted for grading saffron, to detect the adulteration of this spice by Calendula officinalis L. petals (calendula), Carthamus tinctorius L. petals (safflower), and Curcuma longa L. powdered rhizomes (turmeric). To enhance the spectral visibility of these adulterants relative to saffron, we tested various solvents, identifying acetonitrile as the most suitable extraction medium. We analyzed 40 genuine and 123 adulterated saffron samples, each containing 5–10 % w/w contamination (41 samples for each type of adulterant), using acetonitrile extraction. The resulting UV–visible spectra were processed using unsupervised multivariate statistical methods to distinguish between authentic and adulterated saffron. The Sequential Pre-processing through Orthogonalization (SPORT) algorithm, based on sequential and orthogonalized partial least squares (SO-PLS), was first applied to differentiate the two groups. Using a calibration set of 122 samples, the SPORT model correctly classified 37 of 38 external test samples, regardless of the type or level of contamination. Additionally, a class model for genuine saffron was developed using SIMCA (Soft Independent Modelling of Class Analogies), under the same calibration and validation conditions as the SPORT model. SIMCA accurately identified all test samples, with the exception of one pure saffron and one adulterated sample.

Antifungal, antibacterial and DNA binding profile of three novel Zn(II), Cd(II) and Hg(II) complexes of a pyrazole-based Schiff-base ligand: Synthesis, crystal structures, DFT studies and spectroscopic investigation

Three new mononuclear Zn(II), Cd(II) and Hg(II) complexes, [Zn(MPAFA)3](ClO4)2 (1), [Cd(MPAFA)3](ClO4)2 (2) and [Hg(MPAFA)Cl2] (3) of a pyrazole based ‘NN’ bidentate Schiff-base ligand, N-(furan-2-ylmethyl)-1-(5-methyl-1H-pyrazol-3-yl)methanimine, (MPAFA) (L) were synthesized and characterized by elemental analyses, conductance, IR, NMR (1H and 13C), UV-Vis and fluorescence spectral techniques. Molar conductance measurements identified both 1 and 2 as 1:2 electrolytes, while 3 as a non-electrolyte. Single crystal X-ray diffraction studies recognized complexes 1 and 2 as distorted octahedral species with a N6 donor set. The presence of strong non-covalent interactions, such as intramolecular hydrogen bonding and π···π stacking within the complex molecules has been found to contribute to the enhanced stability of the complexes. In absence of single crystal, the structural feature of complex 3 has been confirmed by DFT studies and it has been found to adopt a distorted square-planar geometry with a N2Cl2 coordination. DFT calculations have also been conducted for 1 and 2. The TD-DFT absorption spectral studies supported the experimental results, indicating that the simulated peaks aligned reasonably well with the experimentally resolved peaks. Furthermore, the ligand and all its complexes exhibited effective antifungal activity against Colletotrichum siamense (AP1) and Fusarium equisetum (F.E) fungi. They also displayed promising antibacterial activity against both the gram-negative bacterium Klebsiella sp. (KS) and the gram-positive bacterium Methicillin-resistant Staphylococcus aureus (MRSA). The binding interactions of 1, 2 and 3 with calf-thymus DNA (CT-DNA) have also been studied using a combination of UV-Vis and fluorescence spectroscopic methods.

Forced stability studies and estimation of encapsulated ellagic acid in nano-formulations using UV-spectroscopy

Abstract There is a growing interest in dietary materials to explore their therapeutic activities. Ellagic acid is considered as a dietary supplement and is naturally present in fruits and other foods. It has anticancer, antimalarial, antiviral, antioxidant, and anti-inflammatory activities. These activities can be enhanced with nanoformulations, which can increase its oral bioavailability. However, there is a need for an economical, simple, sensitive, and robust analytical method for the estimation of entrapped ellagic acid in the nanoformulations. Therefore, the present study presents the development and validation of a UV–visible spectroscopy method for the estimation of EA in nanoformulations. The phosphate buffer (pH 7.2) and the detection wavelength of 253.5 nm were used for the method development, and its validation was performed according to the ICH Q2A (R1) guidelines. The coefficient of determination value of the developed method was found to be 0.9988 in the concentration range of 1 μg mL−1 to 6 μg mL−1. The method was found to be linear, precise, sensitive, and robust. This method can be used for the estimation of EA in nanoformulations, bulk dosage forms, and other pharmaceutical formulations.

Unveiling the interaction, cytotoxicity and antibacterial potential of pyridine derivatives: an experimental and theoretical approach with bovine serum albumin.

The binding interactions between bovine serum albumin (BSA) and three pyridine derivatives, i.e., 2-(5-bromopyridin-3-yl) acetic acid (L1), 3-bromo-5-nitropyridine (L2) and 2-chloro-4-nitropyridine (L3), have been carried out using UV-Vis and fluorescence spectroscopic methods. Fluorescence intensity quenching is observed by adding L2 and L3 to the BSA solution. The quenched fluorescence emission is due to the static nature. An isothermal titration calorimetry (ITC) experiment shows the binding ability of L1 with BSA. The binding constants are found to be 7.23 ± 0.32 × 105 M-1 for L1. The thermodynamic parameters were calculated from ITC measurements (i.e., ∆H = -2.78 ± 0.08 kcal/mol, ∆G = -5.65 ± 0.25 kcal/mol, and -T∆S = -2.87 ± 0.11 kcal/mol), which indicated that the protein-ligand complex formation between L1 and BSA is mainly due to the hydrogen bonds and van der Waals interactions. Cyclic voltammetry (CV) and structure activity and relationship (SAR) studies have been carried out to establish the relationship between ligands and proteins. Additionally, we conducted an antibacterial assay with gram-positive Staphylococcus aureus, Enterococcus faecalis, and negative bacterial strains Acinetobacter baumannii and Escherichia coli against L1, L2, and L3, aiming to address the challenges posed by the co-existence of multidrug-resistant bacteria. Finally, drosophila is used to test the cytotoxicity of ligands L1, L2, and L3's in vitro.

Design, synthesis, and quantum chemical calculations of triazole-based aroylhydrazone molecules: Dual assessment of antioxidant properties via in vitro and in silico approaches

In this study, five novel Triazole-Based Aroylhydrazone compounds (6a-e) were synthesized in high yields (87–79 %), starting from deferasirox which has known iron chelator, and characterized with NMR, FTIR, Mass, and UV–vis spectroscopic methods. Quantum chemical calculations of all synthesized molecules were performed at the DFT/B3LYP/6-311G(d,p) level. It was observed that both theoretical and experimental spectral values were compatible. Optimized molecular geometries were acquired from DFT calculations and used in molecular docking studies. Tyrosinase (PDB ID: 3NM8) protein was utilized in molecular docking studies. 6d-3NM8 complex had the highest docking score with the -10.1 kcal/mol. Stabilization of the 6d-3NM8 complex during 100 ns was determined via molecular dynamics simulation. Intramolecular interactions of all molecules were also examined by NCI-RDG analysis. The frequently used cupric ion reducing antioxidant capacity method (CUPRAC) was used to determine the antioxidant activity of synthesized compounds and Trolox which is unknown in the literature on its activity in DMSO. The highest TEAC value was 1.76 (6d) while the lowest one was 1.34 (6e). It is possible to say that the synthesized molecule 6d has the potential to be an antioxidant reagent based on the results of in vitro and in silico antioxidant activity.

PLGA-PEG Nanoparticles Loaded with Cdc42 Inhibitor for Colorectal Cancer Targeted Therapy.

Background/Objectives: An inhibitor of small Rho GTPase Cdc42, CASIN, has been shown to reduce cancer cell proliferation, migration, and invasion, yet it has several limitations, including rapid drug elimination and low bioavailability, which prevents its systemic administration. In this study, we designed and characterized a nanoparticle-based delivery system for CASIN encapsulated within poly(lactide-co-glycolide)-block-poly(ethylene glycol)-carboxylic acid endcap nanoparticles (PLGA-PEG-COOH NPs) for targeted inhibition of Cdc42 activity in colon cancer. Methods: We applied DLS, TEM, and UV-vis spectroscopy methods to characterize the size, polydispersity index, zeta potential, encapsulation efficiency, loading capacity, and in vitro drug release of the synthesized nanoparticles. The CCK-8 cell viability test was used to study colorectal cancer cell growth in vitro. Results: We showed that CASIN-PLGA-PEG-COOH NPs were smooth, spherical, and had a particle size of 86 ± 1 nm, with an encapsulation efficiency of 66 ± 5% and a drug-loading capacity of 5 ± 1%. CASIN was gradually released from NPs, reaching its peak after 24 h, and could effectively inhibit the proliferation of HT-29 (IC50 = 19.55 µM), SW620 (IC50 = 9.33 µM), and HCT116 (IC50 = 10.45 µM) cells in concentrations ranging between 0.025-0.375 mg/mL. CASIN-PLGA-PEG-COOH NPs demonstrated low hemolytic activity with a hemolytic ratio of less than 1% for all tested concentrations. Conclusion: CASIN-PLGA-PEG-COOH NPs have high encapsulation efficiency, sustained drug release, good hemocompatibility, and antitumor activity in vitro. Our results suggest that PLGA-PEG-COOH nanoparticles loaded with CASIN show potential as a targeted treatment for colorectal cancer and could be recommended for further in vivo evaluation.

Development and Validation of UV-Vis Spectroscopic Method for the Determination of Anticancer Drug Crizotinib

Cancer is one of the most leading causes of death in the recent era. A number of cancers based on the affected organ namely stomach cancer, lung cancer, breast cancer, colon cancer etc. Various anticancer drugs are available worldwide where the topnotch one is tyrosine kinase inhibitor. Crizotinib is the recent INN drug which is a tyrosine kinase inhibitor and indicated for non-small cell lung cancer. It is revealed from literature review, there are no developed methods available for determination of crizotinib except HPLC and UPLC methods. In the present study, authors aimed to develop and validate the method based on UV-vis spectroscopy for determination of crizotinib. Crizotinib showed wavelength max (λmax) at 220 nm and 275 nm with a regression equation of y = 0.075x + 0.001, the correlation of Determination (R²) was 0.999, and the correlation coefficient (r) was 0.9995 which indicate the outstanding correlation between concentrations and absorbances along with linearity of the method. The dynamic range was found 1.25 μg/mL to 20 μg/mL for the method. The % RSD of robustness, precision, ruggedness was below 2. Limit of detection and limit of quantification were detected 0.264 μg/mL and 0.8 μg/mL respectively. This paper introduces a new accurate, precise, and simple method for the analysis of crizotinib. The newly developed method can be used for routine quality control of crizotinib.

Multifunctional Nanocomposites Synthesized By Solid-Phase Method with High Photocatalytic, Antibacterial, and Fungicidal Activity

An easily scalable technology was developed for the solid-state synthesis of multifunctional hybrid Ag3PO4/AgCl nanocomposites. This innovative approach relies on solution-free (dry) mechanical activation, implemented through successive ion-exchange reactions in a planetary ball mill. The nanosized hybrid structure of the synthesized Ag3PO4/AgCl nanocomposites was substantiated through the utilization of XRD, SEM, TEM, DSC, and UV-visible spectroscopy methods. The investigation also unveiled a synergistic effect between Ag3PO4 and AgCl.The Ag3PO4/AgCl nanocomposites with a ratio of 75:25 mas. % exhibited the highest and most stable photocatalytic activity under visible light irradiation (λ≥400 nm). The rate constant for the photocatalytic degradation of Methylene Blue (10 mg/L) was found to be two times greater than that observed with Ag3PO4 nanoparticles and four times faster than for AgCl nanoparticles, as illustrated in Figure 1. "In addition, the synthesized nanocomposites remained stable after five cycles of the photocatalytic process, with their activity remaining almost unchanged.Furthermore, the antimicrobial and fungicidal efficacy of these nanocomposites was assessed using Staphylococcus aureus, Candida albicans, Escherichia coli, Pseudomonas aeruginosa, and Erwinia amylovora test strains. The results of the microbiological tests revealed, that almost all prepared materials were able to suppress pathogenic microorganisms. The conducted study identified these nanocomposites as promising candidates for further detailed and targeted studies concerning their interaction with specific microorganisms. Figure - 1. (a) Visible spectrum changes of MB during its photodegradation by the Ag3PO4/AgCl -75/25 composite. (b) Photocatalytic degradation profiles of MB over AgCl, Ag3PO4 and Ag3PO4/AgCl catalysts under visible light irradiation. (c) Graphs for determining the kinetics of decomposition of MS under the influence of different catalysts. (d) Photodegradation stability of MB using the Ag3PO4/AgCl – 75/25 catalyst.AcknowledgmentsThis research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan, grant number АР13068426. Figure 1

Cyanobacterial Phycocyanin-Based Electrochemical Biosensor for the Detection of the Free Radical Hydrogen Peroxide.

Cyanobacteria are photosynthetic prokaryotes that inhabit extreme environments by modifying their photosensitive chemoreceptors called cyanobacteriochromes (CBCRs) which are linear tetrapyrrole-linked phycobilin molecules. These light-sensitive phycobilin from Spirulina platensis is recognized as a potential photoreceptor tool in optogenetics for monitoring cellular morphogenesis. We prepared and extracted highly fluorescent cyanobacterial phycocyanin (C-PC) by irradiating the culture with ambient red light. The crude phycocyanin was subjected to ion exchange chromatography, and its purity was monitored using UV-visible, fluorescence, and FT-IR spectroscopy methods. In the conventional method, red light-induced C-PC exhibited strong antioxidant activity against H2O2, with 88.7% in vitro scavenging activity without requiring any other preservatives. Interestingly, this red light-acclimated phycocyanin was applied as a biosensing material for the detection of the free radical hydrogen peroxide (H2O2) using the enzyme horseradish peroxidase (HRP) as a mediator. The modified C-PC-HRP glassy carbon electrode (GCE) can detect H2O2 from 0.1 to 1600µM. The lowest possible detection limit of the electrode for H2O2 was 19nM. This electrode was used to detect free radical H2O2 in blood serum samples. The microstructure of the lyophilized PC under SEM showed a flat crystal pattern, which enabled the immobilization of HRP on the electrode surface and electron transfer.

Cleaning validation for blister packaging machines in hospital-supplying pharmacies

ObjectiveTo ensure quality-assured care for patients, validation of a cleaning process for blister machines is essential. Due to the high operating costs of maintaining high-performance liquid chromatography (HPLC) which is...

Influence of N 2, N 6-bis((3,5-dimethyl-1h-pyrazol-1-yl)methyl) pyridine-2,6-diamine on C35E steel corrosion in 1 M HCl medium: Experimental and theoretical studies

The inhibition effect of N 2, N 6-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)pyridine-2,6-diamine (MH-PA) on the corrosion of C35E steel in 1 M HCl solution was investigated employing potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), contact angle, X-ray photoelectron spectroscopy (XPS) methods, UV-visible spectroscopy, and theoretical calculation methods. The inhibition efficiency increased with increasing MH-PA concentration and decreased with increasing temperature, attaining 98% inhibition efficiency at 10−3M under 303K. PDP studies indicated that MH-PA is a mixed-type corrosion inhibitor and its adsorption mode conforms to Langmuir isotherm. UV-visible and FTIR spectroscopy support MH-PA adsorption over the C35E steel surface. The surface analysis through SEM, EDS, AFM, and contact angle corroborates the formation of the protective layer of MH-PA molecules on the C35E steel surface. In addition, XPS analysis revealed the formation of an N-Fe bond. Thermodynamic properties revealed that MH-PA has both physical and chemical adsorption behavior. Molecular dynamics simulations manifest that MH-PA molecules adsorb parallel to the Fe (110) surface.

Determination of time since deposition of bloodstains through NIR and UV–Vis spectroscopy – A critical comparison

Time elapsed since bloodstain deposition is a crucial aspect in forensic investigations, where non-destructive spectroscopic methods play a pivotal role. While extensive research has been conducted by UV–Vis spectroscopy, showcasing its utility in specific cases, there is still a paucity of studies based on NIR spectroscopy, which has the potential to overcome the limitations of the UV–Vis-based methods. To compensate for this disequilibrium, the present study aimed to evaluate the NIR applicability for estimating the age of forensic bloodstains and develop a performance comparison with UV–Vis spectroscopy methods. Capillary blood was sampled and subjected to a 16-day aging, during which it was repeatedly analyzed using both spectroscopic methods. Subsequently, chemometric analysis was applied to process the spectral data and independently assess the methods’ performance. Classical preprocessing transforms (i.e., Savitzky-Golay derivatives and SNV transform) were used together with more targeted strategies, such as class centering, whose benefit was highlighted by PCA. Lastly, PLS regression models were computed to evaluate the effectiveness of both spectroscopic methods in estimating the time elapsed since blood trace deposition. Comparable root mean square errors in prediction (RMSEP) – 40 and 55 h for UV–Vis and NIR spectroscopy, respectively – were observed for both techniques, featuring an improvement with respect to the existing literature for NIR spectroscopy. Data fusion strategies for a multi-instrumental platform were also explored, evaluating advantages and disadvantages of low-level and mid-level approaches. The results indicated that NIR spectroscopy integrated with adequate chemometric strategies deserves increased appreciation in forensic bloodstain dating.

Transient radical species and oxygen colorimetric indicators grounded on phenothiazinium dyes

This study investigates four phenothiazinium dyes including methylene blue (MB) and three analogues containing auxochrome variation 2–4 as oxygen colorimetric indicators prepared by their incorporation into two types of oxygen permeable materials containing: a) polyvinyl alcohol substrate with additional TiO2 photocatalysts (PhOxIn), and b) carboxymethylcellulose polymer matrix containing glucose and KOH (ChOxIn). In vacuum packages where volumetric concentrations of oxygen were below 0.01 %, the leuco forms of the tested phenothiazinum dyes were readily oxidised, initiating the colour turn from white to blue. The redox processes involved were explored by experimental electron paramagnetic resonance EPR and UV–vis spectroscopic methods and further supported by theoretical quantum chemistry. The EPR experiments showed that the chemical oxidation of the leuco-form of the phenothiazinium dyes 1–4 produced transient aminyl radical species with the single electron mainly located at the nitrogen atom of the heterocyclic core. The formation of these transient aminyl species was also perceived by UV–vis spectroscopy, their absorption maxima situated in the 552–592 nm range being also supported by TD-DFT theoretical calculations.

Antibacterial and cytotoxicity studies of pyrrolo-based organic scaffolds and their binding interaction with bovine serum albumin.

Two pyrrolo-based compounds, 1H-pyrrolo[3,2-b]pyridine-3-carboxylic acid (L1) and 1H-pyrrolo[3,2-c]pyridine-4-carboxylic acid (L2), were employed for the detection of bovine serum albumin (BSA) by UV-Vis and fluorescence spectroscopic methods in phosphate buffer solution (pH = 7). In the presence of L1 and L2, the fluorescence emission of BSA at 340 nm was quenched and concomitantly a red-shifted emission band appeared at 420 nm (L1)/450 nm (L2). The fluorescence spectral changes indicate the protein-ligand complex formation between BSA and L1/L2. An isothermal titration calorimetry (ITC) experiment was conducted to determine the binding ability between BSA and L1/L2. The binding constants are found to be 4.45 ± 0.22 × 104 M-1 for L1 and 2.29 ± 0.11 × 104 M-1 for L2, respectively. The thermodynamic parameters were calculated from ITC measurements (i.e. ∆rH = -40 ± 2 kcal/mol, ∆rG = -4.57 ± 0.22 kcal/mol and -T∆rS = 35.4 ± 1.77 kcal/mol), which indicated that the protein-ligand complex formation between L1/L2 with BSA is mainly due to the electrostatic interactions. The protein-ligand interactions were studied by performing molecular docking. Further, the antibacterial assay of L1 and L2 was conducted against gram-positive and gram-negative bacterial strains in an effort to address the difficulties caused by the co-occurrence of antimicrobial and multidrug-resistant bacteria. E. coli and S. aureus were significantly inhibited by L1 and L2. The L1 exhibits 13, 12 and 15 mm, whereas L2 exhibits a 2, 3 and 5 mm zone of inhibition against S. aureus, S. pyogenesand E. coli, respectively. In silico molecular docking of L1 and L2 was performed with bacterial DNA gyrase to establish the intermolecular interactions. Finally, the in vitro cytotoxicity activities of the ligands L1 and L2 have been carried out using drosophila.

Emodin Alcohols: Design, Synthesis, Biological Evaluation and Multitargeting Studies with DNA, RNA, and HSA.

A series of novel emodin alcohols were designed and prepared in an effort to overcome the increasing microorganism resistance. Novel emodin alcohols were prepared from commercial emodin and different nitrogen-containing heterocycles via different synthetic strategies, such as O-alkylation and N-alkylation. The antimicrobial activity of synthesized emodin compounds was evaluated in vitro by a two-fold serial dilution technique. The interaction of emodin compound 3d with biomolecule was researched using UV-vis spectroscopic method and fluorescence spectroscopy. Emodin compound 3d containing 2-methyl-5-nitro imidazole ring showed relatively good antimicrobial activity. Notably, it exhibited equivalent activity against S. aureus in comparison to the reference drug norfloxacin (MIC = 4 μg/mL). The combination of strong active compound 3d with reference drugs showed better antimicrobial activity with less dosage and a broader antimicrobial spectrum than their separate use. Further research displayed that emodin compound 3d could intercalate into S. aureus DNA to form the 3d-DNA complex, which might correlate with the inhibitory activity. The hydrogen bonds were found between S. aureus DNA gyrase and strong active compound 3d during the docking research, which were in accordance with the spectral experiment results. The interaction with yeast RNA of compound 3d could also form a complex via hydrogen bonds. The hydrogen bonds were found to play a major role in the transportation of emodin compound 3d by human serum albumin (HSA), as confirmed by molecular simulation. This work provides a promising starting point to optimize the structures of emodin derivatives as potent antimicrobial agents.

Hirshfeld surface analysis, experimental and theoretical evaluation of a new monohydrated organic salt of 2-amino-4‑hydroxy-6-methylpyrimidine (AHMP) and 4-acetamidobenzoic acid (AMBA) for nonlinear optical applications

The organic crystal (AHMP+.AMBA−) of the AHMP and AMBA organic compounds was successfully synthesized and grown by the slow evaporation solution process. The present work focuses on the crystal structure, Hirshfeld surface, spectroscopic and DFT analyses of the title salt. The crystal geometry of AHMP+.AMBA− monohydrated salt was characterized by the single-crystal XRD technique. The synthesized salt crystallizes in the triclinic crystal system and P-1 space group. The identification of the functional groups of the compound has been done by FTIR spectroscopy and DFT/B3LYP-D3/6–311++G(d,p) level of theory. Further, Hirshfeld surface mapping and its associated two-dimensional fingerprint plots predict that the O⋅⋅⋅H and H⋅⋅⋅H interactions are dominant for stabilizing the crystal structure. TG-DTA reveals the crystal is thermally stable up to 168 ºC. The optical studies have been performed by the time-dependent DFT (TD-DFT) and UV–Vis spectroscopic methods. Moreover, the Z-scan experiment has been done to obtain third-order NLO properties. Additionally, the HOMO-LUMO energy gap, MEP maps and theoretical NLO parameters have also been calculated.

Preparation of nanosheet g-C3N4 coupled with Polycalix [4] resorcinarene: Survey characterization and photocatalytic activity for the degradation of 4-Nitrophenol

Here, we have synthesized Polycalix[4]resorcinarene (PC4RA) covalently coupled with carbon-modified porous graphitic carbon nitride (g-C3N4). The nanocomposites were characterized by (FTIR), (XRD), (SEM), Transmission (TEM), and DRS–UV–Vis spectroscopic methods. Photocatalytic activities of the PC4RA/g-C3N4 nanocomposites with different ratios of g-C3N4 were evaluated for degradation of 4-Nitrophenol under visible light irradiation under light irradiation of λ ≥ 320 nm. Three parameters were applied including the initial concentration of 4-nitrophenol, the amount of photocatalyst, and irradiation time. and the results of the photocatalytic performance suggest that the catalytic activity is strongly influenced by the presence of the g-C3N4 content. Especially the nanocomposite’s photocatalytic efficiency was the highest (98.32 % after 120 min) when the ratio of g-C3N4 was (1/2). However, an increase of the photocatalytic activities was related to the interfacial transfer of photogenerated electrons and holes, leading to the effective charge separation. The durability and stability of the nanocomposites have been examined and can endure the experimental conditions even after eight successive cycles. This approach opens up an avenue for the fabrication of graphitic carbon nitrite-based metal-free heterogeneous nanocomposites with high catalytic performance.

Determination of optical properties of single crystal diamond substrates grown via welding-assisted microwave plasma enhanced chemical vapour deposition

Lab grown single crystal diamonds (SCDs) offer unrivalled hardness, a wide range of optical transparency, and supremely high thermal conductivity reliable materials to be a part of devices run at high frequency, temperature, and power. Effective synthesis techniques are essential in enhancing the potential applications of high-quality SCDs. This study aims to decrease the thermal contact resistance between diamond seeds and the molybdenum holder by utilizing welding material. Quality of grown diamond substrates (plates) were assessed by analysing optical properties through Raman, UV-Vis, and FT-IR spectroscopic methods. The findings revealed that the grown single-crystal diamonds have excellent transmittance (>70%) and absorption at 270 nm. Calculations also showed an average absorption coefficient of 1.1 cm−1, indicating the high quality of the grown SCDs with nitrogen impurities below 10 ppm. The absorption observed in the FTIR spectra, ranging from 1600 cm−1 to 2700 cm−1 with a peak at 2354.13 cm−1, is referred to as the “two phonon region,” which is a distinctive feature of the diamond phase.

Phase separation, aggregation, and complexation of triton-X100 and bovine serum albumin mixture: A combined cloud point and UV–visible spectroscopic approaches

Phase separation and aggregation behaviour of triton X-100 (TX-100) and bovine serum albumin (BSA) mixture were investigated using cloud point and UV–visible spectroscopic techniques. The effects of various hydrotropes (HYTs) - namely, sodium salicylate (SS), sodium benzoate (SB), glycerol (Glyc), and 4-aminobenzoic acid (4-ABA) - on the cloud point (CP) of TX-100 + BSA were determined. The obtained CP values for the mixed system in the presence of HYTs followed the order:CPH2O+4−ABA<CPH2O+Glyc<CPH2O+SB<CPH2O+SS. The measured critical micellization concentration (CMC) values of the TX-100 + BSA mixture were found to be significantly altered with varying amounts of BSA. The calculated free energy of clouding and micellization indicated the non-spontaneous nature of the phase transition and the spontaneous association of the TX-100 + BSA mixture. The non-spontaneity of phase separation decreased with increasing concentrations of HYTs. The enumerated values of ∆Hco and ∆Sco were consistently recorded as negative and positive magnitudes, respectively, in all aqueous HYTs media. The clouding process occurred due to a combination of hydrophobic and electrostatic interactions. The binding constant of the mixed system was determined employing the UV–vis spectroscopic method using the Benesi-Hildebrand equation.

Fermentation Kinetics, Potability, and Sensory Compounds of Joubidwi: An Ethnic Alcoholic Beverage

Background: Fermentation is a metabolic pathway of the breakdown of carbohydrate molecules like glucose, fructose to ethanol and various volatile and non-volatile congeners. The production of alcoholic beverages from foodstuffs like rice, cereals, fruits, maize etc., is an age-old traditional protocol. In this study, we adapted the traditional protocol of preparation of the ethnic beverage Joubidwi, with a fermentation time of 6 days, i.e., aliquots from the fermented mash (cooked rice) were collected on a daily basis from day 1 to day 6. Objectives: This study aimed to get insight into fermentation kinetics, ethanol content, carbohydrate content, antioxidant activities, bitterness, protein content, pH, colour, and turbidity of the ethnic alcoholic beverage Joubidwi and to identify the sensory compounds and polyphenol molecules. Method: UV-Visible spectroscopic methods, GC-FID and GC-MS analytics methods were used for the estimation and identification of carbohydrates, proteins, ethanol contents, and sensory compounds, respectively. Reverse phase HPLC was adapted for the identification of polyphenol molecules in Joubidwi. Results: A pseudo-first-order fermentation kinetics was observed from day 1 to day 6 fermentation of Joubidwi. Apart from ethanol content (60.48 ± 1.36 mg/mL after 72 h fermentation to 78.80 ± 1.48 mg/mL after 144 h fermentation), the beverage had nutritional values and good antioxidant properties with 22.38 to 35.11% Radical Scavenging Effect (RSE) from 1 to 6th day of fermented Joubidwi. The beverage also contained 12 sensory compounds. Gallic acid was identified as polyphenol in Joubidwi samples. Conclusion: Joubidwi is an alcoholic beverage prepared by Bodos using rice and certain herbs through a traditional fermentation process. The fermentation process follows pseudo-first-order kinetics. The beverage is potable.