Objective: This paper consists of synthesis of chromium oxide (Cr 2 O 3 ) nanoparticles by sol-gel technique, their characterization and investigation of antibacterial activity of these nanoparticles against pathogenic bacteria by measuring zone of inhibition, colony forming units, and optical density (OD) on solid agar media as well as in liquid medium. Methods:The Cr 2 O 3 nanoparticles were synthesized by sol-gel technique using tetraethylorthosilicate as precursor. The synthesized Cr 2 O 3 nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy (TEM) techniques. The antibacterial effect of these Cr 2 O 3 nanoparticles against Klebsiella pneumoniae was investigated both on the solid agar plates and in liquid medium supplemented with different concentrations of Cr 2 O 3 nanoparticles. The antibacterial activity of Cr 2 O 3 nanoparticles was also compared with the antibacterial activities of the standard antibiotics such as ampicillin, chloramphenicol, penicillin G, streptomycin, sulphatriad, and tetracycline which were taken in the form of hexa discs.Results: Average particle size of the Cr 2 O 3 nanoparticles was found to be 24.0 nm. It was observed that K. pneumoniae is resistant to the penicillin G and ampicillin, but Cr 2 O 3 nanoparticles show good antibacterial property. The minimum inhibitory concentration of Cr 2 O 3 for K. pneumoniae is 2.5 mg/ml. The bacterial growth was monitored by measuring zone of Inhibition, colony formation unit, and OD method. Conclusion:Sol-gel technique is a convenient and easy technique for the synthesis of metal nanoparticles. Nanosized Cr 2 O 3 particles showed an effective antibacterial activity against K. pneumoniae. Therefore, Cr 2 O 3 nanoparticles due to its low manufacturing cost and high effectiveness in antimicrobial properties may find wide applications in various industries to address safety issues.

Objective: The objective of this study was to synthesize the molybdenum oxide nanoparticles (NPs) by employing wet chemical method and investigation of their antibacterial properties against pathogenic bacteria. Methods: Molybdenum trioxide (MoO3) NPs were synthesized using an eco-friendly wet chemical sol–gel technique. The synthesized MoO3 NPs were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy, and ultraviolet-visible spectroscopic techniques to confirm the obtained product, size shape, morphology, functional groups, and absorption spectra, respectively. The size of the MoO3 NPs was found to be 41 nm. The antibacterial activity of these metal NPs was investigated on Staphylococcus epidermidis and Enterobacter aerogenes by measuring the zone of inhibition and colony-forming units on solid medium and by measuring the optical density of the culture solution. Antibacterial activity of MoO3 NPs was also compared with well-known standard antibiotics. Results: The antibacterial activities of molybdenum oxide NPs possessing size 41 nm were compared with standard antibiotics such as oxacillin, cotrimoxazole, erythromycin, clindamycin, chloramphenicol, and tetracycline. It was found that all of these antibiotics were effective against Staphylococcus epidermidis while Enterobacter aerogenes was resistant to oxacillin, co-trimoxazole and clindamycin, whereas the MoO3 nanoparticles were found to be effective against both of these bacterial pathogens. Conclusion: Inorganic antimicrobial agents have advantages over organic antimicrobial agents due to their stability, preparation methods, and their ability to prevent bacteria to develop multidrug resistant. It was observed that MoO3 nanoparticles (NPs) possess good antibacterial properties; therefore, these can be used in pharmaceutical industries and provide a path for further research regarding the toxicity study for its use in human being.

Objective: This study deals with the synthesis of iron oxide nanoparticles by sol-gel technique, their characterization and antibacterial activity of these nanoparticles against Staphylococcus epidermidis. Methods: Hematite (α-Fe2O3) nanoparticles were successfully synthesized by sol-gel method using tetraethyl orthosilicate as a precursor. The structural morphology, size, and chemical state of synthesized iron oxide nanoparticles have been investigated by X-ray diffractometer (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy. The antibacterial activities of these iron oxide nanoparticles were investigated on a pathogenic bacteria S. epidermidis, by measuring the zone of inhibition and colony-forming units on solid medium and by measuring the optical density of the culture solution. Antibacterial activity of iron oxide nanoparticles was also compared with well-known standard antibiotics. Results: It was confirmed from XRD data that the synthesized iron oxide nanoparticles were hematite (α-Fe2O3) nanoparticles. Average particle size of the Fe2O3 nanoparticles was found to be 38.57 nm by XRD characterization. The antibacterial activity of Fe2O3 nanoparticles was almost comparable to the most of the standard antibiotics (taken for comparison), but Fe2O3 nanoparticles were found to be more effective than antibiotic ampicillin and sulfatriad toward S. epidermidis. Conclusion: This study shows that Fe2O3 nanoparticles possess good antibacterial properties; therefore, these metal nanoparticles may be used in place of antibiotics. These inorganic metal nanoparticles can be used by pharmaceutical industries for further research regarding the toxicity study for its use in human being.