Chitosan nanoparticles (CNPs) are promising versatile cationic polymeric nanoparticles, which have received growing interest over last few decades. The biocompatibility, biodegradability, environmental safety and non-toxicity of the chitosan nanoparticles makes it preferred for a wide range of biological applications including agriculture, medical and pharmaceutical fields. In this study, CNPs were biosynthesized by aqueous extract of Eucalyptusglobulus Labill fresh leaves as bio-reductant. Box–Behnken design in 29 experimental runs was used for optimization of different factors affecting the production of CNPs. The maximum yield of CNPs was 9.91 mg/mL at pH of 4.5, chitosan concentration of 1%, incubation time of 60 min and temperature of 50 °C. The crystallinity, particle size and morphology of the biosynthesized CNPs were characterized. The CNPs possess a positively charged surface of 31.1 mV. The SEM images of the CNPs confirms the formation of spherical form with smooth surface. The TEM images show CNPs were spherical in shape and their size range was between 6.92 and 10.10 nm. X-ray diffraction indicates the high degree of CNPs crystallinity. FTIR analysis revealed various functional groups of organic compounds including NH, NH2, C–H, C−O, C–N, O–H, C–C, C–OH and C–O–C. The thermogravimetric analysis results revealed that CNPs are thermally stable. The antibacterial activity of CNPs was determined against pathogenic multidrug-resistant bacteria, Acinetobacterbaumannii. The diameters of the inhibition zones were 12, 16 and 30 mm using the concentrations of 12.5, 25 and 50 mg/mL; respectively. When compared to previous studies, the biosynthesized CNPs produced using an aqueous extract of fresh Eucalyptusglobulus Labill leaves have the smallest particle sizes (with a size range between 6.92 and 10.10 nm). Consequently, it is a promising candidate for a diverse range of medical applications and pharmaceutical industries.

The research highlights the environmentally sustainable biosynthesis of silver nanoparticles from fresh leaves of the herbal medicinal plant Moringa oleifera. They may have been used as anti-inflammatory, anticancer, and antimicrobial agents. M. oleifera extract both reduces and stabilizes silver nanoparticles (AgNPs). Optimum factors needed for AgNP biosynthesis were studied using a central composite design (CCD) matrix. Ultraviolet-visible (UV–Vis) absorption spectroscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy were used to confirm and characterize the synthesized AgNPs. The biogenic AgNPs demonstrated substantial antibacterial potential against the pathogenic strains Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Bacillus subtilis. The antioxidant activity of biosynthesized AgNPs with M. oleifera extract increased from 11.96% when the concentration of the extract was 4 mg/mL to 63.79% at a plant concentration of 20 mg/mL. This research provides an easy and cost-effective technique for the production of stable nanoparticles, with an evaluation of their bioactivity.

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Background Antibiotic resistance is a global problem; especially the multidrug-resistant bacteria are a serious and fatal problem in the intensive care unit. Interestingly, biosynthesized silver nanoparticles are the promising key to eliminate these microbes. Using Pseudomonas aeruginosa supernatant is an easy and cheap method in silver nanoparticle biosynthesis. The biosynthesis conditions were adjusted, and the profiling of the biosynthesized silver nanoparticles was confirmed. Results The UV spectroscopy at a wavelength at 400 nm was 0.539 A.U., transmission electron microscope showed nanoparticles were homogeneous with a square and spherical shape, its average size 20 nm, The capping material and the existence of silver nanoparticles were confirmed using Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy. The minimum inhibitory concentration was 1 mg/ml against multidrug-resistant bacteria, and LC50 was 62.307 μg/ml on the hepatocellular carcinoma cell line. Conclusions Microbial-synthesized silver nanoparticles have a potential application to combat multidrug-resistant bacteria, especially in the intensive care unit.