This review is devoted to the medical application of silver nanoparticles produced as a result of “green” synthesis using various living organisms (bacteria, fungi, plants). The proposed mechanisms of AgNPs synthesis and the action mechanisms on target cells are highlighted.

https://www.mdpi.com/2079-4983/11/4/84/pdf

Silver Nanoparticles: Mechanism of Action and Probable Bio-Application

The present study aimed to explore the biosynthesis and characterization of silver nanoparticles (AgNPs) from Moringa oleifera flower (MOF) extract and its antimicrobial and sensing properties. The prepared AgNPs were characterized by Transmission Electron Microscopy (TEM), UV–visible spectral analysis (UV–vis), X-Ray Diffraction (X-RD), Energy Dispersive Spectroscopy (EDS), and Fourier Infra-Red Spectroscopy (FTIR) respectively. Antimicrobial and sensing properties of the prepared nanoparticles were also determined. Face-Centered Cubic (FCC) lattice of the AgNPs was observed in X-RD pattern. FTIR measurement evidenced the band pattern at 686, 1653, 2062 and 3456 cm−1 proved the presence of proteins and phenolic components in MOF responsible for reduction. TEM analysis indicated the formation of monodispersed spherical particles with 8 nm. UV–vis of the prepared AgNPs authenticated the surface plasmon resonance (SPR) at 429 nm and stable for six months. AgNPs have produced highest zone of inhibition (ZOI) of 17 mm and 29 mm against Klebsiella pneumoniae and Staphylococcus aureus respectively. In addition, the AgNPs effectively detected the presence of Copper ions from 1 mM to 12 mM concentrations. Copper sensitivity of these biosynthesized nanoparticles was carried out by optical sensor based SPR. Thus the obtained antimicrobial and optical properties, suggested the use of obtained AgNPs in water purification.

Green synthesis and characterization of silver nanoparticles from Moringa oleifera flower and assessment of antimicrobial and sensing properties.

In recent years, much attention is focused on silver nanoparticles for biomedical applications and then synthesis using plant procedure has drawn a great focus. In the current study silver nanoparticles were synthesized using the oil cake of Sesamumindicum, which has been used traditionally for several therapeutic purposes. Silver nanoparticles (NPs) were synthesizedin the presence of sesame oil cake. The sesame oil cake facilitated the biosynthesis of silver nanoparticles (SCAgNPs). The synthesized SCAgNPs were subjected to several studies using UV-Visspectroscopy, FTIR, XRD, TEM, and EDS and the particle characteristics were confirmed. The synthesized SCAgNPs was tested for antimicrobial activity using the disk diffusion method. The antitumor activity of the synthesized SCAgNPs was also tested usingbreast cancer cell lines (MCF-7). TEM result revealed spherical shape with a diameter ranging from 6.6 nm to 14.8 nm. Presence of elemental silver in the prepared SCAgNPs was confirmed by EDS. Further a cytotoxicity study was done on two different concentrations of SCAgNPs (2.5 and 7.5 μg/mL) on human breastcancer cell line (MCF-7 cells). Initially, 2.5 μg/mL dose treatment showed a viable cells region of 72.02%, apoptosis 11.81%; late apoptosis 15.18% and necrosis 1.20%. Interestingly, 7.5 μg/mL exhibited substantial cytotoxic effects, viable cells region 56.97%, apoptosis 7.42%, late apoptosis 31.19% and necrosis 4.85%. In the control, viable cells region was 73.72%, apoptosis 10.82%, late apoptosis 14.54% and necrosis 1.58%. The minimum inhibitory concentration (0.5 μg/mL), study was done on P. aeruginosa (27853), K. pneumoniae (70063), E. coli (25922). Silver nanoparticles synthesized using sesame oil cake exhibited a good antibacterial and antitumor activity. Hence it's a first report to spell out the therapeutic effect of AgNPs of sesame oil cake origin.

Eco-friendly green synthesis of silver nanoparticles from the sesame oil cake and its potential anticancer and antimicrobial activities.

Fruits and vegetables are the highly used food products amongst the horticultural crops These items are consumed uncooked, nominally cooked or fully cooked, according to their nature and cooking process With the change in diet habits and rising population, the production, as well as the processing of horticultural crops, has exponentially improved to meet its increasing demand A large amount of peel waste is generated from fruit and vegetable-based industries and household kitchen and has led to a big nutritional and economic loss and environmental problems Processing of fruits and vegetables alone generates a significant waste, which amounts to 25–30% of the total product Most common wastes include pomace, peels, rind and seeds, which are highly rich in valuable bioactive compounds such as carotenoids, enzymes, polyphenols, oils, vitamins and many other compounds These bioactive compounds show their application in various industries such as food to develop edible films, food industries for probiotics and other industries for valuable products The utilization of these low-cost waste horticultural wastes for producing the value-added product is a novel step in its sustainable utilization The present review intends to summarize the different types of waste originating from fruits as well as vegetables peels and highlight their potential in developing edible films, probiotics, nanoparticles, carbon dots, microbial media, biochar and biosorbents

https://www.mdpi.com/1420-3049/25/12/2812/pdf

Fruit and Vegetable Peels: Utilization of High Value Horticultural Waste in Novel Industrial Applications

The field of nanobiotechnology and nanomedicine paves way for the use of several nanoparticles. Especially, in biomedical applications, the silver nanoparticles (AgNPs), gold nanoparticles (AuNPs) and palladium nanoparticles (PdNPs) are found most vital and promising, among other nanoparticles. The biomedical activities of these particles mostly depend on their shape, size and distribution. Preparation of these particles in an eco-friendly method is an immediate need of the society. Herein, AuNPs, AgNPs and PdNPs (MNPS) were synthesized by Solanum nigrum Leaves (SNL) extract. The structural and morphological studies were carried out by using TEM, XRD and EDAX, while the optical and chemical properties were studied using UV–visible spectrum and FTIR spectroscopy. The particles obtained were found to possess a FCC (Face Centered Cubic) structure. TEM images of Ag, Au and PdNPs showed spherical well dispersed nanoparticles with average size of 3.46 nm, 9.39 nm and 21.55 nm respectively. The FTIR spectra confirmed polyphenols and antioxidants in SNL extract act as reducing and capping agents respectively in the synthesis of MNPs. The EDX technique confirmed the presence of silver, gold and palladium nanoparticles. Antimicrobial studies noted that the AgNPs have effective inhibition against E. coli. The complete reduction of 4-Nitrophenol and the formation of 4-Aminophenol with the presence of NaBH4 was chosen for the study of catalytic activities of the prepared MNPs. The reduction time of Au and Pd catalyst were smaller compared to that of Ag. This viable preparation method for producing small spherical shaped nanoparticles expected to the applied to the fields of nanomedicine.

Antimicrobial and catalytic activities of biosynthesized gold, silver and palladium nanoparticles from Solanum nigurum leaves

To address the growing challenges from drug-resistant microbes and tumor incidence, approaches are being undertaken to phytosynthesize metal nanoparticles, particularly silver nanoparticles, to get remedial measure. In this study, an attempt has been made to utilize a major biowaste product, pomegranate fruit peel (Punica granatum), to synthesize silver nanoparticles. The silver nanoparticles (AgNPs) were synthesized using the aqueous extract of pomegranate peel. The formation of synthesized AgNPs was confirmed through UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) as well as through the change of the colorless aqueous solution to a dark brown solution. Using UV-Vis spectroscopy, the dark brown solution showed a Plasmon resonance band peak at 378 nm in UV-Vis spectroscopy after reacting for 24, 48, and 72 h. The XRD report revealed that the AgNPs had a cubic structure. The TEM and SEM report showed the nanoparticles were equally distributed in the solution, with a spherical shape and size ranging from 20 to 40 nm and with an average particle size of 26.95 nm. EDX imaging also confirmed the presence of AgNPs. The synthesized AgNPs were found to exhibit good antimicrobial effects on Gram-negative and Gram-positive bacteria, particularly the pathogens Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27584), Proteus vulgaris (ATCC 8427), Salmonella typhi (ATCC 14028), Staphylococcus aureus (ATCC 29213), Staphylococcus epidermidis (MTCC 3615), and Klebsiella pneumonia. The cytotoxic effects of AgNPs were also tested against a colon cancer cell line (RKO: ATCC® CRL-2577™), and it was observed that the viabilities were 56% and 61% on days 3 and 5, respectively, with exposure to 12.5 μg of AgNPs. This simple, economic, and eco-friendly method suggests that the AgNPs biosynthesized using pomegranate peel extract may be a novel, potent solution for the development of a drug for colon cancer that also has antibacterial activity.

/pdf/antimicrobial-and-cytotoxicity-effects-of-synthesized-silver-iisc6yktmr.pdf

Radhakrishnan Vishnu Balaji

Papers

Antimicrobial and Cytotoxicity Effects of Synthesized Silver Nanoparticles from Punica granatum Peel Extract