UV Vis Spectroscopy Research Articles

Detection of adulterations in native stingless bees honey from Argentina using UV–Vis spectroscopy coupled with chemometrics

Detection of adulterations in native stingless bees honey from Argentina using UV–Vis spectroscopy coupled with chemometrics

LASIS-Assisted Copper Nanoparticle Synthesis and Characterization, along with UV-Visible Spectroscopy

This study investigates the creation of copper nanoparticles (CuNPs) using chemical reduction and laser ablation in liquid (LASIS). UV-visible spectroscopy is used to examine the optical characteristics of the nanoparticles created by these techniques. The purpose of the study is to compare the stability, efficacy, and particle size of CuNPs produced using different techniques. When comparing the LASIS method to the chemical reduction process, Transmission Electron Microscopy (TEM) examination revealed that the former produced smaller and more uniform nanoparticles. This work demonstrates the effectiveness of both synthesis techniques, with LASIS clearly outperforming the other in the production of superior CuNPs with more control over particle size and dispersion. A thorough explanation of the chemical reduction method and LASIS used in the synthesis of copper nanoparticles is provided, and UV-visible spectroscopy is used to characterize the resulting particles.

Characterization and anticancer evaluation of zirconia nanoparticles synthesized via green route using sophora flavescens roots extract

The emergence of drug resistance in cancer cells has impeded recent progress in cancer therapy, leading to the investigation of novel anticancer drugs. The fabrication of metal and ZrO2 nanoparticles is a promising path with prospective applications across diverse technological domains. The present study investigates the potential anticancer effects of ZrO2 NPs obtained from the root extract of Sophora flavescens on MCF-7 breast cancer cells. The structural and chemical features of these nanoparticles are analyzed using several techniques such as flow cytometry, SEM, TEM, FTIR, and UV–vis spectroscopy. The examination of XRD and TEM images demonstrates the significant contribution of plant root extract in enhancing the efficiency of nanoparticles, leading to the formation of nearly tetragonal crystal structures with an average size of 8 nm. The MTT experiment verifies the nanoparticles' anticancer activity, which depends on the dosage. The IC50 value of 253 μg/mL indicates the half-maximal inhibitory concentration. The optical microscope reveals an unusual sight: MCF-7 cells appear more spherical and less dense at higher concentrations. This research also investigates the antibacterial properties of ZrO2 nanoparticles against harmful bacteria, particularly those resistant to multiple drugs. The diffusion disk assay indicates that the nanoparticles are active against drug-resistant isolates, with zones of inhibition ranging from 31 to 55 millimeters. Additionally, the researchers noted a positive correlation between nanoparticle concentration and the size of the inhibition zone. Overall, the data indicates the potential of ZrO2 NPs to aid in cancer therapy as well as in combating infections.

Atomically thin-layered WS2 based resistive sensors for detection of CO and NO2 at room temperature.

The number of layers present in a two-dimensional (2D) nanomaterial plays a critical role in applications that involve surface interaction, for example, gas sensing. This paper reports the synthesis of 2D WS2 nanoflakes using the facile liquid exfoliation technique. The nanoflakes were exfoliated using bath sonication (BS-WS2) and probe sonication (PS-WS2). The thickness of the BS-WS2 was found to range between 70 - 200 nm, and that of PS-WS2 varied from 0.6 to 80 nm, indicating the presence of single to few layers of WS2 when characterized using atomic force microscope (AFM). All the WS2 samples were thoroughly characterized using electron microscopes, X-ray diffractometer, Raman spectroscopy, UV-Visible spectroscopy, Fourier Transform Infrared spectroscope, and thermogravimetric analyser. Both the nanostructured samples were exposed to 2 ppm of NO2 at room temperature. Interestingly, BS-WS2 which comprises of a greater number of WS2 layers exhibited -14.2% response as against -3.4% response of PS-WS2, the atomically thin sample. The BS-WS2 sample was found to be highly selective towards NO2 but was slower (with incomplete recovery) as compared to PS-WS2. The PS-WS2 sample was observed to exhibit -11.9 to - 27.4% response to 2-10 ppm of CO and -3.4 to 35.2% response to 2-10 ppm of NO2 at room temperature, thereby exhibiting the potential to detect two gases simultaneously. These gases could be accurately predicted and quantified if the response times of the PS-WS2 sample were considered. The atomically thin WS2-based sensor exhibited a limit of detection (LOD) of 131 and 81 ppb for CO and NO2, respectively.

Investigation on the Influence of Solvents Environment on the Optoelectronic Properties of the Fluorescent Probe 1,3,4-Oxadiazole Analogues: A Combined Theoretical and Experimental Study.

This study investigates the photophysical properties of a nitrobenzene-substituted 1,3,4-oxadiazole derivative (OX-NO) using both theoretical and experimental methods. The impact of the solvent on OX-NO absorption and fluorescence spectra, as well as its fluorescence quantum yield, was initially studied. A noticeable bathochromic shift in the Stokes shift indicated a π→ π* transition within the molecules. Solute-solvent interactions were analysed using Catalan parameters, distinguishing between specific and nonspecific interactions. Excited state dipole moments were derived from Lippert's, Bakshiev's, and Chamma Viallet's equations, showing increased polarity in the excited state compared to the ground state. Ground state dipole moments were determined via solvatochromic shift methods and ab initio techniques. Additionally, detailed analyses of bond length, angles, dihedral angles, Mulliken charge distribution, and HOMO-LUMO energy gap were conducted using the DFT-B3LYP-6-311G basis set in Gaussian-09W. The energy band gap values obtained from theoretical calculations and experimental methods (cyclic voltammetry and UV-Visible spectroscopy) exhibited excellent agreement. Reactive sites such as electrophilic and nucleophilic regions were identified through total electron density, electrostatic maps, molecular electrostatic potential, and 3D plots using DFT computational analysis. Global descriptors were employed to characterize the compounds' chemical reactivity comprehensively. The observed photophysical attributes underscore the potential of these fluorophores in various applications like organic light-emitting diodes, solar cells, and chemosensors. This study contributes crucial insights into the optoelectronic properties of nitrobenzene-substituted 1,3,4-oxadiazole derivatives, paving the way for their future integration in advanced technological domains.

Introducing the Bis(mesitoyl)phosphide Ligand into Dinuclear Trivalent Rare Earth Metal Chemistry.

Anionic ancillary ligands play a critical role in the construction of rare earth (RE) metal complexes due to the large influence on the stability of the molecule and engendering emergent electronic properties that are of interest in a plethora of applications. Supporting ligands comprising oxygen donor atoms are highly pursued in RE chemistry owing to the high oxophilicity innate to these ions. The scarcely employed bis(acyl)phosphide (BAP) ligands feature oxygen coordination sites and contain a phosphide backbone rendering it attractive for RE-coordination chemistry. Here, we integrate bis(mesitoyl)phosphide (mesBAP) as an ancillary ligand into REIII chemistry to generate the first dinuclear trivalent RE complexes containing BAP ligands; [{mesBAP}2RE(THF)(μ-Cl)]2 (RE = Y, (1), Gd (2), and Dy (3); THF = tetrahydrofuran). Each RE center is ligated to two monoanionic mesBAP ligands, one THF molecule and one chloride ion. All three molecules were characterized through single-crystal X-ray diffraction, 31P NMR, IR and UV-Vis spectroscopy. 31P, 1H and 13C NMR on the diamagnetic yttrium congener 1 confirm asymmetric ligand coordination. DFT calculations conducted on 2 provided insight into the electronic structure. The magnetic properties of 2 and 3 were investigated via SQUID magnetometry. The GdIII ions exhibit weak antiferromagnetic coupling, corroborated by DFT results.

Biochemical properties of novel Carbon nanodot-stabilized silver nanoparticles enriched calcium hydroxide endodontic sealer.

Calcium Hydroxide-based endodontic sealer loaded with antimicrobial agents have been commonly employed in conventional root canal treatment. These sealers are not effective against E. faecalis due to the persistent nature of this bacterium and its ability to evade the antibacterial action of calcium hydroxide. Therefore, endodontic sealer containing Carbon nanodots stabilized silver nanoparticles (CD-AgNPs) was proposed to combat E. faecalis. The therapeutic effect of CD-AgNPs was investigated and a new cytocompatible Calcium Hydroxide-based endodontic sealer enriched with CD-AgNPs was synthesized that exhibited a steady release of Ag+ ions and lower water solubility at 24 hours, and enhanced antibacterial potential against E. faecalis. CD-AgNPs was synthesized and characterized morphologically and compositionally by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy (FTIR), and UV-Vis Spectroscopy, followed by optimization via minimum inhibitory concentration (MIC) determination against E. faecalis by broth microdilution technique and Cytotoxicity analysis against NIH3T3 cell lines via Alamar Blue assay. Calcium hydroxide in distilled water was taken as control (C), Calcium hydroxide with to CD-AgNPs (5mg/ml and 10mg/ml) yielded novel endodontic sealers (E1 and E2). Morphological and chemical analysis of the novel sealers were done by SEM and FTIR; followed by in vitro assessment for antibacterial potential against E. faecalis via agar disc diffusion method, release of Ag+ ions for 21 days by Atomic Absorption Spectrophotometry and water solubility by weight change for 21 days. CD-AgNPs were 15-20 nm spherical-shaped particles in uniformly distributed clusters and revealed presence of constituent elements in nano-assembly. FTIR spectra revealed absorption peaks that correspond to various functional groups. UV-Vis absorption spectra showed prominent peaks that correspond to Carbon nanodots and Silver nanoparticles. CD-AgNPs exhibited MIC value of 5mg/ml and cytocompatibility of 84.47% with NIH3T3 cell lines. Novel endodontic sealer cut-discs revealed irregular, hexagonal particles (100-120 nm) with aggregation and rough structure with the presence of constituent elements. FTIR spectra of novel endodontic sealers revealed absorption peaks that correspond to various functional groups. Novel endodontic sealers exhibited enhanced antibacterial potential where E-2 showed greatest inhibition zone against E. faecalis (6.3±2 mm), a steady but highest release of Ag+ ions was exhibited by E-1 (0.043±0.0001 mg/mL) and showed water solubility of <3% at 24 hours where E-2 showed minimal weight loss at all time intervals. Novel endodontic sealers were cytocompatible and showed enhanced antibacterial potential against E. faecalis, however, E2 outperformed in this study in all aspects.

Searching for "Greener" Bioequivalents of CF3 to Lower its Environmental Impact.

Considering the broad use of the trifluoromethyl functional group (-CF3) in medicinal chemistry and taking into account the recent concerns on the negative environmental effects of CF3 containing compounds, we are searching for "greener" alternatives. Thus, different chemical groups (i.e. iodide, fluoride, cyclopropyl, isopropyl, cyclobutyl, 3-oxetyl, 2-oxetyl, methylsulfide, pentafluorosulfide, methylsulfonyl and sulfonamide) have been considered as potential bioequivalents of -CF3 aiming to use them in compounds with therapeutic interest instead of the polyfluoride functionality. Different structural (molecular surface and volume) and physicochemical (electronic and lipophilic) aspects of the bioequivalent functionalities proposed have been theoretically calculated and compared to those of -CF3. Additionally, the corresponding phenyl derivatives carrying these functionalities have been purchased or prepared and their experimental lipophilicity (i.e. LogP) measured using shake-flask experiments and UV-vis spectroscopy.

Screening of the Medicinal Plant-Based Metabolites Responsible for Silver Nanoparticle Phytofabrication

In this study, the detailed phytochemical composition of two medicinal plants was investigated and their importance in silver nanoparticles (AgNPs) synthesis was highlighted. Aqueous extracts from the leaves of both plants were used for various analytical techniques, including UV-vis spectroscopy, Gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR) and Thin layer chromatography (TLC). Quantification of total phenolics and flavonoids in different fractions of plant extracts revealed significant concentrations. TLC profiling showed a higher abundance of free phenolic and flavonoid compounds compared to bound forms in both plants, suggesting that they contribute significantly to total phenolic and flavonoid content. UV-vis spectra from 200 to 600 nm revealed the presence of aromatic rings and chromophores in leaf extracts. Furthermore, the GC-MS analysis identified several bioactive compounds, some of which were found to be common between these two species. The results demonstrate that various bioactive compounds such as phenols, flavonoids, alkaloids, carotenoids and terpenoids were present in these plant species. These compounds efficiently serve as both reducing and stabilizing agents during phytofabrication of AgNPs, consequently eliminating the need for the use of hazardous chemicals.

Bimetallic magnetic nanoparticles dispersed in glycerol: An efficient hydrophilic catalyst for the reduction of 4‐nitrophenol

A one‐pot, ecologically friendly method for the preparation of Fe/Ni, Fe/Co and Co/Ni bimetallic magnetic nanoparticles (MNPs) was reported, using glycerol as both a solvent and reducing agent. Six different bimetallic MNPs by varying the proportions of transition metals, namely, Fe, Co and Ni were synthesized by the chemical reduction method. The catalytic efficiency of the synthesized nanoparticles (NPs) was explored for the reduction of 4‐nitrophenol, and the reaction rate for different catalysts was systematically analysed. Especially, glycerol‐Fe/Co (1:3) bimetallic nanoparticles as a magnetically recoverable catalyst had higher catalytic activity than the other bimetallic nanoparticles for the reduction of 4‐nitrophenol to 4‐aminophenol in the presence of sodium borohydride. The reduction process was monitored by UV–visible spectroscopy, and the reaction was complete within 8 min. The kinetic study shows 99% conversion of 4‐nitrophenol to 4‐aminophenol, and the rate constant is 0.593 min−1. Furthermore, the glycerol‐Fe/Co (1:3) MNPs were retrieved from the reaction mixture and subsequently utilized in five consecutive cycles, demonstrating both the reusability and durability of the NPs as a catalyst. This research was remarkable for its fast reaction kinetics, simplified one‐pot conversion of 4‐nitrophenol to 4‐aminophenol without the need for mechanical or magnetic stirring and in‐depth study of six bimetallic MNPs' catalytic properties in nitro reduction. These findings explored the potential benefits of bimetallic magnetic NPs for the synthesis of 4‐aminophenol products.

Myco-fabricated silver nanoparticle by novel soil fungi from Saudi Arabian desert and antimicrobial mechanism

Biological agents are getting a noticeable concern as efficient eco-friendly method for nanoparticle fabrication, from which fungi considered promising agents in this field. In the current study, two fungal species (Embellisia spp. and Gymnoascus spp.) were isolated from the desert soil in Saudi Arabia and identified using 18S rRNA gene sequencing then used as bio-mediator for the fabrication of silver nanoparticles (AgNPs). Myco-synthesized AgNPs were characterized using UV–visible spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy and dynamic light scattering techniques. Their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae were investigated. In atrial to detect their possible antibacterial mechanism, Sodium dodecyl sulfate (SDS-PAGE) and TEM analysis were performed for Klebsiella pneumoniae treated by the myco-synthesized AgNPs. Detected properties of the fabricated materials indicated the ability of both tested fungal strains in successful fabrication of AgNPs having same range of mean size diameters and varied PDI. The efficiency of Embellisia spp. in providing AgNPs with higher antibacterial activity compared to Gymnoascus spp. was reported however, both indicated antibacterial efficacy. Variations in the protein profile of K. pneumoniae after treatments and ultrastructural changes were observed. Current outcomes suggested applying of fungi as direct, simple and sustainable approach in providing efficient AgNPs.

Aerosol Deposition of CuFeO2 Photocathode Coatings for Hydrogen Production

AbstractPhotoelectrochemical (PEC) water splitting is a viable route for green hydrogen generation. In PEC cells, the electrodes are coated with suitable semiconductor materials, which absorb the sunlight, generating charge carriers that are used to split water molecules into H2 and O2. CuFeO2 is one promising photocathode material for water splitting. However, its performance is limited by electron/hole pairs recombination within the film and at the film/substrate interface. Aerosol deposition (AD) can be employed to minimize charge recombination by spraying dense, thin films and by establishing a good back-contact interface. In this study, CuFeO2 powders were synthesized through a conventional solid-state technique and sprayed by AD under varied parameter sets. The effect of particle size distributions, carrier gas, gas pressure and substrate temperature was investigated. The best spraying parameter set was then tuned to obtain thin coatings (&lt; 1 µm). Single-particle deformation and coatings microstructure were investigated by scanning electron microscopy. Optical properties of CuFeO2 films were analyzed by UV–Vis spectroscopy, while photoelectrochemical performances were estimated through amperometry tests under simulated sunlight. The results of this research show that CuFeO2 photocathodes can be successfully manufactured by AD. Their performance can be optimized by adjusting coating thickness and by annealing in air.

Highly twisted 1,3,4‐oxadiazole based hybrid fluorescent organic materials: Synthesis, characterization, density functional theory calculations, and optoelectronic study

AbstractHeterocyclic compounds based on 1,3,4‐oxadiazole (ODA) have attracted considerable attention in the field of pharmacy, drug discovery, and in the field of material sciences. This article reports a series of new highly twisted blue‐ and green‐emitting ODA‐based materials 4(a–e) utilizing a simple and efficient synthetic approach, resulting in high yield. The formation of multiple CN bonds unfolds via a simple nucleophilic method that does not need costly metal catalysts. The derivative structures were validated using analytical methods such as 1H NMR, 13C NMR, and high‐resolution mass spectrometry (HRMS). Using fluorescence spectroscopy, UV–Vis spectroscopy, and fluorescence lifetime measurements, a thorough investigation was carried out on the photophysical characteristics of the newly synthesized derivatives. A deeper understanding of intramolecular charge transfer was uncovered via solvent‐dependent spectroscopy. Specifically, these materials show a large stock shift of up to 153 nm and long fluorescence decay value between 8 and 8.6 ns. Computational methods pinned on density functional theory (DFT) were used to determine the highest occupied molecular orbital–lowest unoccupied molecular orbital energy gaps. The optical band gaps derived from absorption peaks and the band gaps computed by DFT computations are highly correlated. Using cyclic voltammetry study, the compounds' redox potentials were further investigated. These results indicate that the ODAs 4(a–e) are promising organic materials and could play an important role in the field of optoelectronic devices, bioimaging, and photo‐redox reactions.

Facile synthesis of copper nitroprusside chitosan nanocomposite and its catalytic reduction of environmentally hazardous azodyes

One of the biggest issues affecting the entire world currently is water contamination caused by textile industries’ incapacity to properly dispose their wastewater. The presence of toxic textile dyes in the aquatic environment has attracted significant research interest due to their high environmental stability and their negative effects on human health and ecosystems. Therefore, it is crucial to convert the hazardous dyes such as methyl orange (MO) azo dye into environmentally safe products. In this context, we describe the use of Copper Nitroprusside Chitosan (Cu/SNP/Cts) nanocomposite as a nanocatalyst for the chemical reduction of azodyes by sodium borohydride (NaBH4). The Cu/SNP/Cts was readily obtained by chemical coprecipitation in a stoichiometric manner. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy were applied to investigate chemical, phase, composition, and molecular interactions. Additionally, Scanning electron microscope (SEM) was used to examine the nanomaterial's microstructure. UV–vis spectroscopy was utilized for studying the Cu Nitroprusside Chitosan's catalytic activity for the reduction of azodye. The Cu/SNP/Cts nanocomposite demonstrated outstanding performance with total reduction time 160 s and pseudo-first order constant of 0.0188 s−1. Additionally, the stability and reusability study demonstrated exceptional reusability up to 5 cycles with minimal activity loss. The developed Cu/SNP/Cts nanocomposite act as efficient nanocatalysts for the reduction of harmful Methyl orange azodye.

Co-Encapsulation of Paclitaxel and Doxorubicin in Liposomes Layer by Layer

The synergistic effect of antineoplastic drug co-encapsulation systems has made them highly regarded due to their improved pharmacological efficacy. Biopolymer-coated liposomes were evaluated for paclitaxel and doxorubicin co-encapsulation in MCF-7 and MDA-MB-231 breast cancer cell lines. These nanosystems are characterized by dynamic light scattering, transmission electron microscopy, and UV–VIS spectroscopy. The conventional and hybrid liposomal systems presented sizes of 150 to 230 nm and %EE greater than 80% for the encapsulated active ingredients. These drug-laden liposomal systems significantly decreased cell viability in both breast cancer cell lines compared with liposome-free drugs. The delivery of antineoplastic drugs in breast cancer therapy could potentially benefit from new hybrids for drug co-encapsulation.

Nano-Integrated Plant Tissue Culture to Increase the Rate of Callus Induction, Growth, and Curcuminoid Production in Curcuma longa.

Turmeric has attracted a significant amount of interest in recent years due to its strong antimicrobial properties. The tissue culture of turmeric is preferred to obtain disease-free, highest number of plantlets with good uniform chemistry. However, there is a need to increase the speed of the whole process to meet the growing demand for planting materials and to save time and resources. Iron oxide nanoparticles (Fe3O4 NPs) showed positive effects on callus initiation time, proliferation rate, percent root response, shoot length, percent rooting, and number of roots per explant. Highest callus induction, i.e., 80%, was recorded in cultures that were grown in the presence of 15 mg/L of Fe3O4 NPs. Callus initiated earlier in culture tubes that received green synthesized iron nanoparticles in a concentration between 10-15 mg/L. Biofabricated nanoparticles were characterized for their size, physiochemical, and optical properties through UV-Vis spectroscopy, FTIR, XRD, and SEM. Curcuminoids profiling was performed by implementing LC-Ms that revealed increased quantities in plantlets grown in nano-supplemented media when compared to the control.

Thin Film Formation of HSA in the Presence of CTAB-Capped Gold Nanorods through Phase Separation.

Phase behavior in protein-nanoparticle systems in light of protein corona formation has been investigated. We report the formation of HSA thin films following the addition of a solid protein to a solution of CTAB-capped gold nanorods (AuNRs) via phase separation. The phase separation behavior was observed through UV-vis spectroscopy, turbidity assays, and DLS studies. UV-vis spectra for the protein-AuNR solution indicated a possible self-assembly formation by CTAB-HSA complexes and AuNR-HSA conjugates. The turbidity was found to increase linearly up to 30-50% v/v for each component. The growth phase slope is proportional to the concentration of the components, AuNRs, and HSA, with no lag phase. Dynamic light scattering (DLS) shows the formation of larger aggregates with time, implying a segregated phase of AuNR-HSA and a CTAB-HSA-AuNR network. ζ-potential values confirm surface modification, implying protein corona formation on nanorods. The thin films were also characterized using SEM, AFM, SAXS, XPS, FTIR, and TGA studies. SEM images show a smooth surface with a reduced number of pores, indicating the compactness of the deposited structure. AFM shows two different structural pattern formations with the deposition, indicating possible self-assembly of the protein-conjugated nanoparticles. FTIR studies indicate a change in the hydrogen bonding network and confirm the CTAB-HSA-AuNR complex network formation. The XPS studies indicate Au-S bond formation, along with Au-S-S-Au interactions. SAXS studies indicate the formation of aggregates (oligomers), as well as the presence of dominant attractive intermolecular interactions in the thin films.

Study of temperature-dependent copper iodide thin film by thermal evaporation system

Abstract The development of heterostructure devices has gained significant attention towards scientific communities in the present time. This article reports on the effective use of the horizontal thermal evaporation (TE) method to successfully fabricate copper iodide (CuI) films on silicon (Si) substrates. By using the TE technique, CuI-based heterojunctions have been fabricated here. CuI exhibits semiconductor qualities of the p-type, making it a promising option for optoelectronic devices in the future. The temperature was varied from room temperature (RT) to 230 °C to synthesise the CuI/Si heterojunction. The structural, morphological, optical, and electrical analyses have been carried out with various substrate temperatures. The X-ray diffraction (XRD) data show that CuI films have demonstrated a polycrystalline character and have lattice parameters of 6.03 Å. The Raman spectroscopy study shows the microstructural analysis of CuI films. The field emission scanning electron microscopy (FESEM) study reveals the variation of grain size and shape with synthesis temperature. The atomic force microscope (AFM) was used to estimate the surface roughness. The CuI films were found to be p-type by the Hall effect measurement. The sample synthesised at 130 °C shows the highest mobility of 83.12 cm2 V-1 s-1 with a carrier concentration of 1019 cm-3. The UV-visible (UV-Vis) spectroscopy measurements show good absorption of UV light by the CuI thin films. The CuI/Si heterojunctions are rectifying, as demonstrated by the I-V measurements, and they respond well to UV light irradiation.

Green synthesis of silver nanoparticles using Senna alexandrina leaf extracts and their antibacterial, larvicidal, nanotoxicity and photocatalytic activity

Biological synthesis of metal nanoparticles has been discovered in recent years, and they have been effectively manufactured and studied from diverse plant extracts. Recent research has shown that nanoparticles have extremely promising antibacterial, larvicidal and anticancer effects. The current study aimed to synthesize Senna alexandrina leaf extract-mediated silver nanoparticles (SA-AgNPs) as are reducing and capping agent. The produced SA-AgNPs were characterized by using UV–visible spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and Field emission scanning electron microscopy with energy dispersive spectroscopy (FESEM-EDS). The result showed synthesized SA-AgNPs were confirmed by UV–visible spectroscopy with 440 nm absorption. FT-IR analysis shows the presence of phosphine, primary amines, carboxylic acids, ether, and alkyl halides biomolecules in both plant extract and SA-AgNPs. XRD findings revealed the crystalline structures of produced SA-AgNPs. The spherical shape of SA-AgNPs with an average size of 20–35 nm was confirmed using FESEM. The SA-AgNPs show better antibacterial activity against E. coli (18.0 ± 0.25 mm), S. aureus (17.2 ± 0.36 mm), P. aeruginosa (16.8 ± 0.12 mm), and leaf extract of S. alexandrina showed minimal antibacterial activity. The SA-AgNPs show 100 % mortality for both Cx. quinquefasciatus and Ae. aegypti after 48 hrs. The brine shrimp lethal assay of the SA-AgNPs shows 100 % at 30 µg after 24 hrs of brine shrimp which indicated the presence of cytotoxicity this suggests that produced SA-AgNPs are slightly toxic. The photocatalytic activity was also tested using reactive orange 16 (RO16) and phenol red (PR) with the percentage of degradation being about 93.95 % and 92.91 % respectively. These results suggest that biosynthesized SA-AgNPs have promising properties that can be used as an effective biomedical and environmental protectant.

Enhancing radical scavenging using reduced graphene oxide based metal organic frameworks: A comparative study

This work reports the facile fabrication of reduced graphene oxide (rGO) based metallic (R) (copper (Cu), silver (Ag), gold (Au) and trimetallic (Tm)) nanocomposites or metal organic frameworks (MOFs) using glucose as a reducing and stabilizing agent in an eco-friendly and low-cost method. The morphology, physicochemical properties and size of different nanocomposites were determined by Scanning Electron Microscopy (SEM), UV–Visible spectroscopy, Transmission electron Microscopy (TEM), Cyclic voltametry and Raman spectra, respectively. In comparative experimental investigations, antioxidant behavior of rGO, RNPs (metallic nanoparticles: AuNPs, CuNPs, AgNPs, TmNPs (trimetallic NPs), rGO-RNPs (rGOCuNPs, rGO-AgNPs, rGO-AuNPs, and rGO-TmNPs or Au@Ag@Cu decorated rGO) was explored for the first time. The antioxidant behavior was estimated by radical scavenging assays viz. total antioxidant, ferric power reducing and hydrogen peroxide assay. Interestingly, antioxidant properties of rGO-RNPs nanocomposite (R-Cu/Au/Ag/Tm)) were found to be arranged in the descending order of AA (ascorbic acid)>rGO-TmNPs > TmNPs >rGOCuNPs > rGO-AgNPs > rGO-AuNPs >AgNPs > CuNPs > AuNPs for total antioxidant assay. In similar way order or arrangmet was rGO-TmNPs > rGO-AgNPs > rGO-AuNPs > AuNPs > TmNPs > rGOCuNPs > AA >AgNPs > CuNPs for hydrogen peroxide scavenging method. And order of arrangment was found to be rGO-TmNPs-GO > rGOCuNPs > rGO-AgNPs > rGO-AuNPs > CuNPs > AgNPs > AuNPs> TmNPs > AA using ferric reducing power assay. These findings indicated that TmNPs decorated rGO showed the best antioxidant capabilities among rGO, RNPs and rGO-RNPs nanocomposites. Furthermore, electrochemical assessment of kinetic parameters (such as peak separation potential, peak current, diffusion coefficient, k°, Ψ, concentration of ionic species etc.) estimated using cyclic voltammetry provided insight towards favourable drift obsereved in all these parameters, that appear to be contributing towards improved conducting behavior. This behavior could also have emerged from improving the disorder in sp2/sp3 carbon of rGO and metal nanoparticles, thereby improving the stability and favorable ease in transfer of electrons between metal NPs and rGO surface. Since these metallic RNPs were found to be uniformly distributed onto rGO surface, this synergistic amalgamation of rGO and multi-metallic nanoparticles possess great potential for low cost, eco-friendly opportunities to tap various environmental and industrial applications. Further investigations to assess catalytic applications, clinical diagnostics and antimicrobial activity estimations are under way.