Fabricating BiOCl/BiVO4 nanosheets wrapped in a graphene oxide heterojunction composite for detection of an antihistamine in biological samples

Antibiotics are essential medications for human and animal health, as they are used to battle urinary infections and bacterial diseases. Therefore, the rapid determination of antibiotic drugs in biological samples is necessary to address the current clinical challenge. Here, we developed a heterojunction ternary composite of BiOCl/BiVO₄ nanosheets enriched with graphene oxide (BiOCl/BiVO₄@GO) for accurate and minimal-level detection of an antihistamine (promethazine hydrochloride, PMZ) in urine samples. The BiOCl/BiVO₄ nanosheets were prepared by a wet chemical approach using a deep eutectic green solvent. The spectroscopic and analytical methods verified the formation and interaction of the BiOCl/BiVO₄@GO composite. Our results showed that the thoroughly exfoliated BiOCl/BiVO₄@GO composite retained good electrical conductivity and fast charge transfer toward the electrode-electrolyte interface in neutral aqueous media. In addition, the experimental conditions were accurately optimized, and the BiOCl/BiVO₄@GO composite showed excellent electrocatalytic activity toward the oxidation of PMZ. Indeed, the BiOCl/BiVO₄@GO composite demonstrated a good linear response range (0.01-124.7 μM) and a detection level of 3.3 nM with a sensitivity of 1.586 μA μM^-1 cm^-2. In addition, the BiOCl/BiVO₄@GO composite had excellent storage stability, good reproducibility, and reliable selectivity. Finally, the BiOCl/BiVO₄@GO displayed a desirable recovery level of PMZ in urine samples for real-time monitoring.

Bismuth molybdate incorporated functionalized carbon nanofiber as an electrocatalytic tool for the pinpoint detection of organic pollutant in life samples

Herein, we fabricated a feasible and accurate sensing platform for the quantification of toxic organic pollutant 2-nitroaniline (2-NA) in water samples through electrocatalyst made up of bismuth molybdate (Bi₂MoO₆, BMO) functionalized carbon nanofiber (f-CNF) modified electrode. The preparation of BMO/f-CNF composite is of two methods, such as co-precipitation (C-BMO/f-CNF) and ultrasonication method (U-BMO/f-CNF). The physicochemical properties of the composites were characterized by XRD, FTIR, Raman, BET, FE-SEM, and HR-TEM techniques. At U-BMO/f-CNF, the charge transfer resistance was low (R_ct = 12.47 Ω) compared to C-BMO/f-CNF because nanosized U-BMO particles correctly aim at the defective sites of the f-CNF surface wall. Further, the electrocatalytic activity of C&U-BMO/f-CNF composites was examined by cyclic voltammetry (CV) and differential pulse voltammetry techniques (DPV) for the electrochemical detection of 2-nitroaniline (2-NA). The U-BMO/f-CNF/GCE shows a higher cathodic current, wide dynamic linear range of 0.01-168.01 µM, and superior electrocatalytic activity with a low detection limit (0.0437 µM) and good sensitivity (0.6857 μA μM^-1 cm^-2). The excellent selectivity nature of U-BMO/f-CNF/GCE was observed in the presence of various organic pollutants and a few toxic metal cations. The practical applicability such as stability, repeatability towards 2-NA outcomes with accepted results. Besides, the practical viability of as proposed U-BMO/f-CNF sensor was investigated in soil and lake water samples delivers good recovery results. Hence from these analyses, we conclude that U-BMO/f-CNF/GCE potential for the determination of hazardous environmental pollutant 2-NA.

Exploring the photochemosensitivity by novel cysteine-based mixed ligand complexes

A new series of cysteine-based metal(II) complexes with 2,2'-bipyridine or 1,10-phenanthroline as co-ligand have been prepared and characterized. Their DNA binding and cleavage properties have been studied. The analytical and spectroscopic data of complexes 1-18 reveal that the complexes adopt an octahedral geometry around the central metal ion in which the cysteine is coordinated through NS and NN atoms, respectively. Spectroscopic titration and viscosity measurements reveal that the complexes bind to DNA through an intercalative mode. Electrophoresis measurements exhibit that they cleave pBR322 DNA efficiently in the presence of 3-mercaptopropionic acid (MPA), probably via hydrolytic mechanism with the involvement of (•)OH. The in vitro anticancer activities indicate that the Cu(II) complexes are active against four selected human tumor cell lines. Furthermore, it is remarkable that all the complexes exhibit significant photocytotoxicity against human breast cancer cell lines (MCF-7) with a potency more than the widely used drugs photofrin and cisplatin indicating that they have the potential to act as effective anticancer drugs in a dose-dependent manner.

Efficient interrupting skills of amino acid metallointercalators with DNA at physiological pH: evaluation of biological assays

The 4-aminoantipyrine derivatives (NO2, OCH3) and their mixed-ligand complexes with amino acids have been synthesized and investigated for their binding with CT DNA using UV-visible spectroscopy, cyclic voltammetry, and viscosity measurements under physiological conditions of pH (stomach 4.7; blood 7.4). The results from all techniques i.e. binding constant (Kb), and free energy change (ΔG) were in good agreement and inferred spontaneous compound-DNA complexes formation via intercalation. Among all the compounds 1 and 4 showed comparatively greater binding at pH 7.4 as evident from its greater Kb values. All the complexes exhibit oxidative cleavage of supercoiled (SC) pBR322 plasmid DNA in the presence of H2O2 as an activator. It is remarkable that at 25μM concentration 1 and 4 completely degrade SC DNA into undetectable minor fragments and thus they act as efficient chemical nucleases. Among the new complexes, complexes 1 and 4 have highest potential against all the microorganisms tested. The results of the above biological experiments also reveal that the choice of different metal ions has little influence on the DNA binding, DNA cleavage and antimicrobial assay.

DNA binding mode of novel tetradentate amino acid based 2-hydroxybenzylidene-4-aminoantipyrine complexes

Few transition metal complexes of tetradentate N(2)O(2) donor Schiff base ligands containing 2-hydroxybenzylidene-4-aminoantipyrine and amino acids (alanine/valine) abbreviated to KHL(1)/KHL(2) have been synthesized. All the metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The Schiff bases KHL(1)/KHL(2) are found to act as tetradentate ligands using N(2)O(2) donor set of atoms leading to a square-planar geometry for the complexes around the metal ions. The binding behaviors of the complexes to calf thymus DNA have been investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The DNA binding constants reveal that all these complexes interact with DNA through minor groove binding mode. The studies on mechanism of photocleavage reveal that singlet oxygen ((1)O(2)) and superoxide anion radical (O(2)(-)) may play an important role in the photocleavage. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae and antifungal activities against Aspergillus niger, Fusarium solani, Culvularia lunata, Rhizoctonia bataicola and Candida albicans by MIC method.