Vis Absorption Spectroscopy Research Articles

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

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

Colourful 3-amino-1,8-naphthalimide alkyl-substituted fluorescent derivatives

The optical properties of four 3-amino-1,8-naphthalimide derivatives differing in the degree of substitution at the amino functionality were synthesised and studied by UV–visible absorbance and fluorescence spectroscopy in 1:1 (v/v) methanol/water and methanol. The compounds were structurally characterized by NMR, IR and HRMS. The charge transfer absorbance band was observed to shift to longer wavelength with increasing ethyl substitution. The emission band was also observed to shift to longer wavelengths with a decrease in the emission intensity with increasing ethyl substitution due to the peri effect. Irradiation of dye methanol solutions and in the solid state with a 365 nm UV lamp reveals distinct emission colours for each compound. Significantly larger Stokes shifts are observed in methanol than in mixed aqueous methanol. Quantum chemical calculations at the B3LYP/TZVP level of theory provided insight into the optimized ground state geometry, frontier molecular orbitals levels and solute-solvent dynamics revealing a stronger hydrogen bond between the 3-amino-1,8-naphthalimides and methanol in the lowest S1 excited state. The dyes were tested as fluorescent stains in MCF-7 cancer cells and observed to emit green emission in various organelles.

Enhanced photocatalytic performance of two-dimensional NixRe1-xSe2 (x = 0 & 0.25) crystalline material: Exploring its potential as a high-efficiency catalyst

Water pollution, stemming primarily from dye effluent discharge in urban and industrial zones, remains a critical environmental issue. Photocatalysis emerges as a promising eco-friendly, cost-effective, solar-dependent, and recyclable solution. This study synthesizes Ni0.25Re0.75Se2 via a simple Direct Vapour Transport (DVT) technique, exploring the impact of doping on ReSe2's structural, optical, and photocatalytic properties. Characterization techniques (PXRD, FESEM, EDAX, Raman spectroscopy, UV–visible absorbance spectroscopy, XPS) were employed for analysis. Photocatalytic experiments with organic dyes like Methylene Blue (MB), Acridine Orange (AO), Crystal Violet (CV) demonstrated efficient AO dye degradation (95.67 %) in 60 min using Ni0.25Re0.75Se2, showcasing effective catalytic properties under 20W LED bulb. Trapping experiments identified hydroxyl radicals and holes as pivotal for AO dye degradation. Ni0.25Re0.75Se2 exhibited stability under varying pH, non-leaching behavior, and retained efficiency over cycles, showcasing potential for sustained use in industrial wastewater treatment. This research advances sustainable solutions to combat water pollution in urban and industrial environments.

Synthesis, optical properties and self-assemblies of a new halogenated BODIPY dye with long alkoxy chain

A new boron-dipyrromethene (BODIPY) dye modified with two bromine atoms at the 2,6-positions and three hydrophobic p-(dodecyloxy)styryl groups at 3,5,8-positions was designed and synthesized. Its molecular structure was characterized by 1HNMR and MALDI-TOF-MS. The photophysical properties and aggregate behavior of dye 3 in solution were studied by UV–visible absorption and fluorescence spectroscopy. The dye 3 exhibited strong absorption and a high fluorescence quantum yield in different solvents. The self-assembly behaviors were investigated in THF and water mixtures, and the J-aggregates can be formed. Supramolecular self-assembly behavior of dye 3 was confirmed by temperature-dependent UV−Vis absorption. In addition, the self-assembly behavior of dye 3 in liquid-solid interface was studied using scanning tunneling microscopy (STM) and displays highly ordered linear arrangement on HOPG. The self-assembly processes are found to be adjusted by halogen bonding as well as π−π stacking.

Stability assessment of PTB7‐Th and a quinoxaline‐based polymer in both organic thin film transistors and in organic photovoltaic devices

AbstractHerein, we perform a stability assessment of two conjugated polymers that are conventionally used as electron donor polymers in the active layer of organic photovoltaic (OPV). More specifically, the impact of thermal annealing, a post‐treatment commonly applied in the OPV community, is evaluated in terms of device performance and stability. The two polymers are PTB7‐Th and QX1, and they are respectively blended with a non‐fullerene electron acceptor, herein a derivative of N‐annulated perylene diimide, that is, tPDI2N‐EH. These blends are targeted for their relatively high power conversion efficiency in outdoor conditions, but also for their potential as efficient active layer in low‐intensity (indoor) conditions—while these blends have been reported, no study on the impact of thermal annealing on their stability has been performed yet. The performance stability of these devices, tracked via the open circuit voltage, the short‐circuit current, the fill factor, and the power conversion efficiency metrics, were evaluated each day for 2 weeks and correlated to an evaluation of the microstructure of the active layer, evaluated using atomic force microscopy and UV–visible absorbance spectroscopy. Finally, transistors were prepared using only the two electron donor polymers, PTB7‐Th and QX1, to assess if some correlations could be made between the behaviour of the OPV devices and that of the electronic charge mobilities. Results contribute to identify which molecular structures and which post‐treatments are ideal to promote the stability of the active layers in the context of OPV devices.

A new method for the rapid identification of external water types in rainwater pipeline networks using UV–Vis absorption spectroscopy

Ultraviolet–visible (UV–Vis) absorption spectroscopy, due to its high sensitivity and capability for real-time online monitoring, is one of the most promising tools for the rapid identification of external water in rainwater pipe networks. However, difficulties in obtaining actual samples lead to insufficient real samples, and the complex composition of wastewater can affect the accurate traceability analysis of external water in rainwater pipe networks. In this study, a new method for identifying external water in rainwater pipe networks with a small number of samples is proposed. In this method, the Generative Adversarial Network (GAN) algorithm was initially used to generate spectral data from the absorption spectra of water samples; subsequently, the multiplicative scatter correction (MSC) algorithm was applied to process the UV–Vis absorption spectra of different types of water samples; following this, the Variational Mode Decomposition (VMD) algorithm was employed to decompose and recombine the spectra after MSC; and finally, the long short-term memory (LSTM) algorithm was used to establish the identification model between the recombined spectra and the water source types, and to determine the optimal number of decomposed spectra K. The research results show that when the number of decomposed spectra K is 5, the identification accuracy for different sources of domestic sewage, surface water, and industrial wastewater is the highest, with an overall accuracy of 98.81%. Additionally, the performance of this method was validated by mixed water samples (combinations of rainwater and domestic sewage, rainwater and surface water, and rainwater and industrial wastewater). The results indicate that the accuracy of the proposed method in identifying the source of external water in rainwater reaches 98.99%, with detection time within 10 s. Therefore, the proposed method can become a potential approach for rapid identification and traceability analysis of external water in rainwater pipe networks.

Formation of Layered Liquid Crystal by Cooperation of Sidechain Array and Rigid Polyacetylene Mainchain

ABSTRACT An acetylene derivative monomer with a pyrimidine – type sidechain with three rings was synthesized by Steglich esterification. Polymerization of the acetylene derivative was then carried out with a rhodium complex. The acetylene monomer and mono-substituted polyacetylene derivative showed liquid crystals (LCs) because their tricyclic parts worked as a mesogenic core. The monomer as an acetylene derivative showed smectic with a tilted structure in the LC aggregation form. The mono-substituted polyacetylene bearing mesogen via short alkyl spacer showed lyotropic and thermotropic LCs of the smectic phase, although generally flexible long alkyl spacer from the main chain connected to sidechain mesogen is required for exhibiting liquid crystal in sidechain type polymer liquid crystals. In the present study, rigid mainchain aligns the sidechain mesogen array to form non-tilted LC. Properties of LCs were evaluated by various analytical techniques, including polarizing optical microscopy. Structural properties were evaluated by nuclear magnetic resonance spectroscopy, gel permeation chromatography, infrared spectroscopy, and ultraviolet – visible absorption spectroscopy.

Facile preparation and study of supramolecular architecture of an efficient nanocomposite LB film AHSM/SA based on azo-functionalized hockey stick-shaped mesogen at air-water and air-solid interface

Hockey stick-shaped mesogens are fascinating thermotropic liquid crystal systems owing to their exceptional supramolecular assembly properties and shape anisotropy compared to conventional rod-and bent-shaped mesogens. In this article, we present an investigation of the supramolecular organization of a new azo-functionalized hockey stick-shaped mesogen with stearic acid at the air-water interface and air-solid interfaces by applying the Langmuir-Blodgett film deposition method. The incorporation of stearic acid can change the molecular organization of azo-functionalized hockey stick-shaped mesogen at an aqueous interface through hydrophobic-hydrophobic interactions and form a supramolecular nanostructure at the solid interface. The interfacial nature of the Langmuir monolayer was studied by recording the isotherm (surface pressure area, π–A), which was further analyzed by using Brewster angle microscopy. The significant reduction in molecular area, increased surface pressure, and lower isotherm slope of the AHSM/SA composite mixture indicate the hybrid AHSM/SA monolayer's greater stability compared to pure AHSM. BAM images of the AHSM/SA composite signify nanostructure aggregates formed by the interaction of AHSM and SA molecules at the air-water interface. Field emission scanning electron microscopic analysis of composite films revealed the formation of supramolecular domains. The impact of changing the surface pressure and the number of depositions on the morphology of the composite film surface was monitored using field emission scanning electron microscopy. The supramolecular H-type aggregation of azo-functionalized hockey stick-shaped mesogen and stearic acid molecules in the composite LB film was characterized using UV–visible absorption and steady-state fluorescence spectroscopy. The adsorption of stearic acid onto azo-functionalized hockey stick-shaped mesogen via hydrophobic interactions was confirmed by Fourier transform infrared spectroscopy of the composite Langmuir Blodgett film. Further, Raman spectroscopy of the LB films of the AHSM/SA composites is distinct from the pristine film components due to the merging of signals at similar wave numbers for both SA and AHSM with a lack of typical packing pattern further supported by PXRD studies of the films.

Contrasting Photosensitized Processes of Ru(II) Polypyridyl Structural Isomers Containing Linear and Hooked Intercalating Ligands Bound to Guanine-Rich DNA.

The DNA binding and cellular uptake of the lambda enantiomer of two bis-tetraazaphenanthrene (TAP) Ru(II) polypyridyl complexes containing either a linear dppn (1) or a hooked bdppz (2) benzodipyridophenazine ligand are reported, and the role of different charge-transfer states of the structural isomers in the photo-oxidation of guanine is explored. Both complexes possess characteristic metal-to-ligand charge-transfer (MLCT) bands between 400 and 500 nm and emission at ca. 630 nm in an aerated aqueous solution. Transient visible absorption (TrA) spectroscopy reveals that 400 nm excitation of 1 yields a dppn-based metal-to-ligand charge-transfer (MLCT) state, which in turn populates a dppn intraligand (3IL) state. In contrast, photoexcitation of 2 results in an MLCT state on the TAP ligand and not the intercalating bdppz ligand. Both 1 and 2 bind strongly to double-stranded guanine-rich DNA with a loss of emission. Combined TrA and time-resolved infrared (TRIR) spectroscopy confirms formation of the guanine radical cation when 2 is bound to the d(G5C5)2 duplex, which is not the case when 1 is bound to the same duplex and indicates a different mechanism of action in DNA. Utilizing the long-lived triplet excited lifetime, we show good uptake and localization of 2 in live cells as well as isolated chromosomes. The observed shortening of the excited-state lifetime of 2 when internalized in cell chromosomes is consistent with DNA binding and luminescent quenching due to guanine photo-oxidation.

An inclusive comparison regarding aggregation of surface active ionic liquid and conventional surfactant with a cationic dye Acridine Red exposed in view of spectroscopic and theoretical study

The investigation was conducted on the interaction of acridine red (AR) with sodium dodecyl sulfate (SDS) and 1-butyl-3-methyl imidazolium octyl sulfate (BMImOS) in both premicellar and post micellar concentrations. The interaction between AR and room temperature ionic liquid (RTIL) 1-butyl-3-methyl imidazolium bromide (BMImBr) was studied to understand the effect of imidazolium cation on micellization. Spectroscopic experiments, such as UV–visible absorption spectroscopy, steady-state fluorescence spectroscopy, time-resolved fluorescence spectroscopy, and dynamic light scattering, have been introduced. Various important parameters like spectral shifts, anisotropy, and aggregation number have been determined spectroscopically. However, a fresh insight into density functional theory calculations has also been provided. The observed results have been explained in terms of the aggregation behavior of the amphiphiles. A prominent redshift accompanied by a change in intensity is observed in the presence of surfactant and SAIL. However, in the case of BMImBr, no such spectral shift has been observed; only a decrease in spectral intensity highlights the quenching ability of the imidazolium cation. Average lifetime also provides some additional information regarding the difference in the formation of aggregates by SDS and BMImOS, which is further established from particle size density obtained from DLS. The salt like role of 1-butyl-3-methyl imidazolium cation also has been logically explained by anisotropy measurement and the determination of aggregation number. Using Gauss View 5.0 and Gaussian 09 package, the energy of optimization of each set of amphiphiles along with dye has been determined to follow the interaction at the molecular level. TDDFT calculations have also been performed to determine the structure of HOMO and LUMO.

Cytotoxic properties of Pelargonium graveolens leaf extract and its green-synthesized gold nanoparticles (in vitro study)

ObjectiveThis study aimed to assess the cytotoxic effects of an extract from Pelargonium graveolens leaves and green-synthesized gold nanoparticles (AuNPs) in a mouthwash when used as a substitute for commercial mouthwashes. Human dermal fibroblasts from neonates (HDFn) were used in this study that done in vitro, because their characteristics were nearly identical to those of human gingival fibroblasts. MethodIn this study, the green synthesis of AuNPs using extracts from P. graveolens leaves was investigated as a sustainable and economical method. Then, using a range of analytical techniques, the physicochemical properties were evaluated, such as transmission electron microscopy (TEM), X-ray diffraction (XRD), and ultraviolet visible absorption spectroscopy (UV–Vis), so the preparations and analytical techniques of P. graveolens gold nanoparticles (AuNPs) take little time is about 10 days. The current study used the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl-tetrazolium bromide Mosmann's Tetrazolium Toxicity (MTT) to study the cytotoxic effects of P. graveolens leaf extract with P. graveolens gold nanoparticles (AuNPs) utilizing a human fibroblast-derived standard cell line. ResultsVarious doses (1000, 500, 250, 100, 50, 25, 12.5, 6.25, and 3.125 μg/mL) of P. graveolens AuNPs were used to assess cytotoxicity, demonstrating little cytotoxic effects (approximately below 20% toxicity). A high level of biocompatibility was observed between the P. graveolens AuNPs and normal human fibroblasts. ConclusionThe mouthwash made using green synthetic AuNPs obtained from P. graveolens leaf extract show high level of biocompatibility and has low cytotoxicity. Therefore, herbal mouthwash formulations can serve as a viable substitute for chemical mouthwashes.

Mussel shell-derived biogenic hydroxyapatite as reinforcement on chitosan-loaded gentamicin composite for antibacterial activity and bone regeneration

In this study, hydroxyapatite (HAp) was synthesized from natural biowaste materials, specifically mussel shells, and combined with chitosan (CS) and gentamicin sulfate antibiotic (GA) using an in-situ method. The resulting composite material, designated HAp/CS-GA, has its physicochemical and structural properties characterized by Fourier transform infrared spectroscopy (FTIR) analysis. The structure was confirmed by X-ray diffraction (XRD) analysis. Additionally, field emission scanning electron microscopy (FE-SEM) equipped with the energy dispersive X-ray spectroscopic (EDX) technique was used to determine the surface topography and main components. The composite of HAp/CS-GA was analyzed using a drug release profile by UV–visible spectroscopy (UV–Vis). The fabricated composites antimicrobial behavior was examined against bone infection-causing Gram-positive and Gram-negative bacteria, showing potential activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus compared to Escherichia coli, respectively. Simultaneously, the cytotoxicity of the composite was evaluated by MTT assay using an MG-63 osteoblast-like cell line that exhibited no toxicity in the prepared composite. After a 24 h incubation period, the MG-63 cells on the HAp/CS-GA composite showed good proliferation, according to Hoechst 33258 fluorescence staining results. The results suggested that the composite had excellent biocompatibility and antibacterial activity and enhanced the osteoblast cell proliferation. Therefore, the designed HAp/CS-GA composite would be a promising candidate for bone tissue engineering.

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

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

Salinity effect on corrosion inhibition of 2-mercaptopyrimidine as an inhibitor in CO2-containing solution

In this work, the effects of Cl-, Ca2+, and Mg2+ on the corrosion inhibition performance of 2-mercaptopyrimidine (2-MP) were investigated. The analysis reveals a marked reduction in the inhibition efficiency of 2-MP, from 91.24 % to 76.29 %, as the NaCl content in the solution rises from 1 wt% to 20 wt%. UV–visible absorption spectroscopy and quartz crystal microbalance measurements indicate that the desorption of 2-MP worsens with an increasing content of corrosive ions. Molecular dynamics simulations reveal the inhibitor desorption mechanism. This work enhances understanding of ion effects on corrosion inhibition and film degradation in high salinity environments.

The mechanism of interaction between tri-para-cresyl phosphate and human serum protein: A multispectroscopic and in-silico study

Organophosphate flame retardants (OPFRs) pose the significant risks to the environment and human health and have become a serious public health issue. Tricresyl phosphates (TCPs), a group of aryl OPFRs, exhibit neurotoxicity and endocrine disrupting toxicity. However, the binding mechanisms between TCPs and human serum albumin (HSA) remain unknown. In this study, through fluorescence and ultraviolet–visible (UV–vis) absorption spectroscopy, molecular docking and molecular dynamics (MD), tri-para-cresyl phosphate (TpCP) was selected to explore potential interactions between HSA and TCPs. The results of the fluorescence spectroscopy demonstrated that a decrease in the fluorescence intensity of HSA and a blue shift were observed with the increasing concentrations of TpCP. The binding constant (Ka) was 2.575 × 104 L/mol, 4.701 × 104 L/mol, 5.684 × 104 L/mol and 9.482 × 104 L/mol at 293 K, 298 K, 303 K, and 310 K, respectively. The fluorescence process between HSA and TpCP involved a mix of static and dynamic quenching mechanism. The gibbs free energy (ΔG0) of HSA-TpCP system was −24.452 kJ/mol, −25.907 kJ/mol, -27.363 kJ/mol, and - 29.401 kJ/mol at 293 K, 298 K, 303 K, and 310 K, respectively, suggesting that the HSA-TpCP reaction was spontaneous. The enthalpy change (ΔH0) and thermodynamic entropy change (ΔS0) of the HSA-TpCP system were 60.83 kJ/mol and 291.08 J/(mol·>k), respectively, indicating that hydrophobic force was the major driving force in the HSA-TpCP complex. Furthermore, multispectral analysis also revealed that TpCP could alter the microenvironment of tryptophan residue and the secondary structure of HSA and bind with the active site I of HSA. Molecular docking and MD simulations confirmed that TpCP could spontaneously form a stable complex with HSA, which was consistent with the fluorescence experimental results. This study provides novel insights into the mechanisms of underlying the transportation and distribution of OPFRs in humans.

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.

Simultaneous purification and oxidation of the as-synthesized MWCNTs with KMnO4 using phase transfer catalyst at three different pH medium by the hydrothermal method

Improving and streamlining current oxidation techniques for experimental is the main goal of the research described in the present article. By applying the pressure created while on the hydrothermal process to an autoclave walled with Teflon, simplifying the procedure was accomplished. By comparing the degrees of functionalization attained with the dispersibility in the substantially pure and functionalized multi-walled carbon nanotubes (MWCNTs) final product, the beneficial effect of the procedure was evaluated. In order to achieve this, the study looked at and investigated how as-synthesized MWCNTs from Fe-Mo/MgO catalyst were simultaneously purified and oxidized using the chemical vapor deposition (CVD) method. Aliquot-336 was used as phase transfer catalyst (PTC) by hydrothermal method under three different pH conditions. Following functionalization, nanotubes of carbon might easily combine with various chemical reagents to generate homogeneous dispersions or even well-aligned structures because of the functional groups linked to their surfaces. In this case, a chemical called reagent potassium permanganate (KMnO4) is necessary in order to target particular π-bonds while entirely destroying the nanotubes' graphene structures. The techniques have been explained in terms of mechanism, and the Fourier transform-infrared (FT-IR) spectroscopy has confirmed the functionalizations of the CNTs. These approaches were further explored through FT-Raman spectrum analysis, thermal assessments, energy dispersive X-ray spectroscopy (EDX), TEM (transmission electron microscopy) along with the help of EDX, and visible-near IR absorption and UV–visible absorption spectroscopy (ABS) procedures.

Biosynthesis, Antibacterial and Antifungal Activities of Ag Nanoparticles Prepared Using Piper nigrum Fruit Extract

Nanomaterials are promising alternatives to antibiotics with the potential to handle the menace of emerging multidrug resistance in pathogenic microbes. We report a simple biosynthetic approach to prepare Ag nanoparticles (NPs) with strong antibacterial and antifungal actions by using Piper nigrum fruit extract as a bioreducing agent. The biosynthesized material was characterized by SEM, AFM, TEM, HRTEM, XRD and UV–Visible absorption spectroscopy. SEM, AFM and TEM analyses provided evidence that the average diameter of the Ag NPs was 18[Formula: see text]nm, while XRD and HRTEM confirmed the FCC structure of Ag NPs. The biosynthesized Ag NPs demonstrated extremely strong antibacterial activity against Bacillus oceanisediminis and Escherichia coli, and showed extremely strong antifungal action against Schizosaccharomyces pombe, inhibiting their growth at very low concentrations of 3[Formula: see text][Formula: see text]g/mL, 4[Formula: see text][Formula: see text]g/mL and 3[Formula: see text][Formula: see text]g/mL, respectively. The molecular origin of their antibacterial and antifungal activity was studied using various molecular and biochemical assays. The results of these assays revealed a major role for reactive oxygen species (ROS) in the antifungal and antibacterial actions of the biosynthesized Ag NPs. Furthermore, morphological changes in cells and cell wall damage upon Ag NP treatment were observed by scanning electron microscopy. In addition, significant enhancement in protein leakage and fragmentation of DNA was also observed upon treatment of S. pombe, B. oceanisediminis and E. coli with Ag NPs. In conclusion, the observed extremely strong antibacterial and antifungal activities of biosynthesized Ag NPs are due to the oxidative stress triggered by ROS, causing cell wall damage and subsequent protein leakage and DNA fragmentation.

Charge transfer interaction dynamics between 6-Aminoindole and picric acid: Synthesis, spectrophotometric, characterization, computational, DNA binding, and anticancer properties

The charge transfer complex (CT) chemistry is studied between electron donor 6-Aminoindole (AMI) and electron acceptor Picric acid (PA) at 25 °C, in an acetonitrile medium by using UV–Visible absorption spectroscopy. The molecular ratio of the CT complex was determined to be 1:1 by using jobs variation and spectrophotometric titration processes. To assess the stability constant (KCT), and molar extinction coefficient (ƐCT) by using the Benesi-Hildebrand equation. These outcomes reveal that the synthesized CT complex is highly stable. The thermodynamic study is carried out in different temperatures (20-45 °C), and these results indicate increases the stability with increasing temperature. The CT complex structure was analyzed by FT-IR, 1H NMR, and 13C NMR. The surface morphology and elemental composition were identified by the SEM-EDX technique. The crystalline nature was analyzed by powdered XRD investigation. The CT complex has been screened for DNA binding and invitro cytotoxicity. The DNA binding constant value (2.3 × 105 M−1) and in vitro cytotoxicity test results on HeLa, suggest that it could be used as a potential medicinal drug in the future. Finally, the geometry optimizations were carried out by the DFT with the wB97XD method and 6-31+G(d,p) basis set. Here we investigated different parameters like bond parameters, NBO analysis, FMO analysis, DOS, PDOS, and computed electronic spectra. The computational analysis provided additional support for the experimental CT complex formation.

The impact of lithium concentration on the optical properties of colloidal ZnO nanocrystals

In this work, Li-doped ZnO nanocrystals (LZO) were synthesized via the sol–gel method. The concentration of zinc acetate has been set at 2 M in order to prepare the highly concentrated Li-doped ZnO sol. The generated LZO sol’s optical characteristics were assessed using UV–visible absorption and photoluminescence spectroscopy, while the ZnO nanopowders’ lithium doping process was assessed using XRD and Raman spectroscopy. The experimental findings indicate that the concentration of Li+ ions in the synthesized zinc oxide nanocrystals has reached the maximum solid solubility limit. The inclusion of Li+ ions results in a reduction in the size of ZnO nanocrystals, accompanied by a notable increase in violet-blue emission, distinguishing them from other materials reported in the literature. As can be found, Li+ ions cannot change the type of conductivity in thin ZnO films, and they have n-type conductivity.