Influence of High Annealing Temperature on Structural, Magnetic and Antimicrobial Activity of Silver Chromite Nanoparticles for Biomedical Applications

Biosynthesis of Silver, Copper, and Their Bi-metallic Combination of Nanocomposites by Staphylococcus aureus: Their Antimicrobial, Anticancer Activity, and Cytotoxicity Effect

The present study outlines an easy, cheap, and environmentally friendly way to make Staphylococcus aureus-mediated bimetallic silver-copper nanocomposites (Ag/Cu) that can fight cancer and germs. The gram-positive S. aureus synthesized Ag, Cu, and their bi-metallic nanocomposites extracellularly. We aimed to prepare the bimetallic nanocomposite in two different ways, and we compared them in terms of characterization and biological applications. The first one is a bimetallic nanocomposite (Ag/Cub) that was made by mixing Ag and Cu metal ions in equal amounts (50:50). Then, the whole mixture was reduced. The second is the after-reduction bimetallic nanocomposite (Ag/Cua), in which each metal ion was reduced separately, and then the nanocomposites were mixed (50:50%) during biological applications. Nanocomposites were characterized using UV-visible spectrophotometry, Fourier-transform infrared spectroscopy, dynamic light scattering, and transmission electron microscopy. The results demonstrated that surface plasmon bands were at 320 nm for Ag NPs and 525 nm for Cu NPs, and a shift from these peaks was observed at 290 nm in the Ag/Cub bimetallic nanocomposite. The synthesized nanocomposites were confirmed to be in the nanoscale with 20, 40, and 80 nm spherical crystals, respectively. Nanocomposites were assayed for their antimicrobial activity against the gram-negative Pseudomonas aeruginosa, the acid-fast Mycobacterium smegmatis, the gram-positive Bacillus cereus, and S. aureus, in addition to three fungal species, which were Aspergillus flavus, A. fumigatus, and Candida albicans. The minimum inhibitory concentration and minimum bactericidal concentration were determined. The Ag/Cua/Cuaetallic nanocomposite was the most potent antimicrobial compound. The anticancer activity of the tested compounds was assayed against the hepatocellular carcinoma cell line (HepG-2). Low cytotoxic activity was recorded in most assayed nanocomposites against the baby hamster kidney cell line (BHK).

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-024-01229-2.

Impact of different magnetic materials added to silver-magnetite nanoparticles on the structural, magnetic and antimicrobial properties

Different magnetic materials of spinel copper and cobalt nanoferrites added to silver-magnetite nanoparticles were fabricated by a facile, low cost, and rapid auto-combustion method to form a nanocomposite. X-ray diffraction patterns and atomic force microscopy were studied for the investigated samples and confirmed their nanosize range. Adding cobalt nanoferrite to silver-magnetite (CoAF) yielded a more pronounced effect in the magnetic measurements than adding copper nanoferrite (CuAF). This result was attributed to the much higher coercivity H c and saturation magnetization M s (5.7-fold and 2.8-fold, respectively) of CoAF than CuAF; accordingly, the CoAF nanocomposite can be applied to a permanent magnet. Next, the operating frequencies of the nanocomposites were calculated from the magnetic measurements. The CoAF and CuAF nanocomposites were applicable in the microwave super-high-frequency C-band and the microwave super-high-frequency S-band, respectively. Both nanocomposites were ineffective against the tested fungi but showed strong antimicrobial activities against the tested Gram-positive and Gram-negative bacteria. Thus, CoAF and CuAF nanocomposites are potential antibacterial nanomaterials for biomedical applications.

Attractive study of the antimicrobial, antiviral, and cytotoxic activity of novel synthesized silver chromite nanocomposites

Antibiotic resistance is a global problem. This is the reason why scientists search for alternative treatments. In this regard, seven novel silver chromite nanocomposites were synthesized and assayed to evaluate their antimicrobial, antiviral, and cytotoxic activity. Five bacterial species were used in this study: three Gram-positive (Bacillus subtilis, Micrococcus luteus, and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella enterica). Three fungal species were also tested: Candida albicans, Aspergillus niger, and A. flavus. The MIC of the tested compounds was determined using the bifold serial dilution method. The tested compounds showed good antibacterial activity. Maximum antibacterial activity was attained in the case of 15 N [Cobalt Ferrite (0.3 CoFe₂O₄) + Silver chromite (0.7 Ag_0.5Cr_2.5O₄)] against M. luteus. Concerning antifungal activity, C. albicans was the most susceptible fungal species. The maximum inhibition was recorded also in case of 15 N [Cobalt Ferrite (0.3 CoFe₂O₄) + Silver chromite (0.7 Ag_0.5Cr_2.5O₄)]. The most promising antimicrobial compound 15 N [Cobalt Ferrite (0.3 CoFe₂O₄) + Silver chromite (0.7 Ag_0.5Cr_2.5O₄)] was assayed for its antiviral and cytotoxic activity. The tested compound showed weak antiviral activity. The cytotoxic activity against Mammalian cells from African Green Monkey Kidney (Vero) cells was detected. The inhibitory effect against Hepatocellular carcinoma cells was detected using a MTT assay. The antimicrobial effect of the tested compounds depends on the tested microbial species. The tested compounds could be attractive and alternative antibacterial compounds that open a new path in chemotherapy.

Evaluation of antimicrobial properties of a novel synthesized nanometric delafossite

Antibiotics and other antimicrobial compounds are the backbone of clinical medicine. Antimicrobial resistance can cause serious diseases to man. Nanotechnology can improve therapeutic potential of medicinal molecules and related agents. Widespread application of antibiotics and other antimicrobial compounds led to development of multidrug-resistant microbes, so there is need to develop novel therapeutic agents. Novel synthesized nanometric delafossite was assayed against two Gram-positive bacteria (Staphylococcus aureus and Micrococcus luteus), two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae), four opportunistic fungi (Aspergillus flavus, A. fumigatus, A. niger, and Fusarium solani), and four Candida species (C. albicans, C. parapsilosis, C. krusei, and C. tropicalis) using diffusion assay method. The minimum inhibitory concentration (MIC) of the novel synthesized nanometric delafossite was determined using the dilution method. The assayed compounds showed different degrees of antifungal and antibacterial activities, depending on the annealing temperature of preparation of these compounds. Compounds prepared at room temperature showed greater antimicrobial activities than those prepared at higher temperatures. The antimicrobial activity depends also on the susceptibility of the test microbe.