Green Biological Synthesis of Nanoparticles and Their Biomedical Applications

Alnafisah A, Beji L, Kouki N, Morlet-Savary F, Alminderej FM, Aroua LM, Lalevée J. Photochemical Synthesis of Noble Metal Nanoparticles: Influence of Metal Salt Concentration on Size and Distribution

This paper explores the photochemical synthesis of noble metal nanoparticles, specifically gold (Au) and silver (Ag) nanoparticles, using a one-component photoinitiator system. The synthesis process involves visible light irradiation at a wavelength of 419 nm and an intensity of 250 mW/cm2. The radical-generating capabilities of the photoinitiators were evaluated using electron spin resonance (ESR) spectroscopy. The main objective of this study was to investigate how the concentration of metal salts influences the size and distribution of the nanoparticles. Proposed mechanisms for the photochemical formation of nanoparticles through photoinitiated radicals were validated using cyclic voltammetry. The results showed that the concentration of AgNO3 significantly impacted the size of silver nanoparticles, with diameters ranging from 1 to 5 nm at 1 wt% and 3 wt% concentrations, while increasing the concentration to 5 wt% led to an increase in the diameter of silver nanoparticles to 16 nm. When HAuCl4 was used instead of AgNO3, it was found that the average diameters of gold nanoparticles synthesized using both photoinitiators at different concentrations ranged between 1 and 4 nm. The findings suggest that variations in HAuCl4 concentration have minimal impact on the size of gold nanoparticles. The photoproduction of AuNPs was shown to be thermodynamically favorable, with the reduction of HAuCl4 to Au0 having ∆G values of approximately -3.51 and -2.96 eV for photoinitiators A and B, respectively. Furthermore, the photoreduction of Ag+1 to Ag0 was demonstrated to be thermodynamically feasible, with ∆G values of approximately -3.459 and -2.91 eV for photoinitiators A and B, respectively, confirming the effectiveness of the new photoinitiators on the production of nanoparticles. The synthesis of nanoparticles was monitored using UV-vis absorption spectroscopy, and their sizes were determined through particle size analysis of transmission electron microscopy (TEM) images.

A green and environmental sustainable approach to synthesis the Mn oxide nanomaterial from Punica granatum leaf extracts and its in vitro biological applications

Pathogenic fungal infections in fruit cause economic losses and have deleterious effects on human health globally. Despite the low pH and high water contents of vegetables and fresh, ripened fruits, they are prone to fungal and bacterial diseases. The ever-increasing resistance of phytopathogens toward pesticides, fungicides and bactericides has resulted in substantial threats to plant growth and production in recent years. However, plant-mediated nanoparticles are useful tools for combating parasitic fungi and bacteria. Herein, we synthesized biogenic manganese oxide nanoparticles (MnONPs) from an extract of Punica granatum (P. granatum), and these nanoparticles showed significant antifungal and antibacterial activities. The production of MnONPs from plant extracts was confirmed by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and UV visible spectroscopy (UV). The surface morphology and shape of the nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using a detached fruit method, the MnONPs were shown to exhibit significant antimicrobial activities against two bacterial strains, E. coli and S. aureus, and against the fungal species P. digitatum. The results revealed that the MnONPs had a minimum antimicrobial activity at 25 µg/mL and a maximum antimicrobial activity at 100 µg/mL against bacterial strains in lemon (citrus). Furthermore, the MnONPs exhibited significant ROS scavenging activity. Finally, inconclusive results from the green-synthesized MnONPs magnified their significant synergetic effects on the shelf life of tomatoes (Lycopercicum esculantum) and indicated that they could be used to counteract the phytopathological effects of postharvest fungal diseases in fruits and vegetables. Overall, this method of MnONPs synthesis is inexpensive, rapid and ecofriendly. MnONPs can be used as potential antimicrobial agents against different microbial species.

Viola betonicifolia-Mediated Biosynthesis of Silver Nanoparticles for Improved Biomedical Applications

We report the biosynthesis of silver (Ag) nanoparticles (NAPs) (LEVB-Ag NAPs) by an environmentally friendly green synthesis approach using the phytoconstituents of Viola betonicifolia leaf extract. The spectroscopic techniques were employed to characterize biosynthesized LEVB-Ag NAPs successfully. Biosynthesized LEVB-Ag NAPs were assessed for antibacterial and antimycotic activities against bacterium and mycological strains (H. pylori, S. epidermidis, C. tropicalis, and T. rubrum) using the serial dilution method. They were also evaluated for their biofilm inhibiting potential against both bacterial and fungi species. They were further assessed for the cytobiocompatible potential with two normal cell lines (293T and hMSC). The results demonstrate that the biosynthesized LEVB-Ag NAPs showed superior log₁₀ reduction in bacterial and fungal growth and presented more than 99.50% killing efficiency. Moreover, biosynthesized LEVB-Ag NAPs excellently inhibited the biofilm formation of bacterial (Gram-positive and Gram-negative) and mycological strains and presented more than 80% biofilm inhibiting percentage compared to both plant extract and CHE-Ag NAPs. They further presented good cytobiocompatibility in vitro with 293T and hMSC cells compared to CHE-Ag NAPs. Biosynthesized LEVB-Ag NAPs presented superior antibacterial, antimycotic, biofilm inhibition, and cytobiocompatible results that might be attributed to the synergistic effect of the NAPs’ physiochemical properties and the immobilized phytoconstituents from plant leaf extract on their surface. Hence, biosynthesized LEVB-Ag NAPs may be a promising contender for a variety of therapeutic applications.

Plant-derived nanotherapeutic systems to counter the overgrowing threat of resistant microbes and biofilms

Since antiquity, the survival of human civilization has always been threatened by the microbial infections. An alarming surge in the resistant microbial strains against the conventional drugs is quite evident in the preceding years. Furthermore, failure of currently available regimens of antibiotics has been highlighted by the emerging threat of biofilms in the community and hospital settings. Biofilms are complex dynamic composites rich in extracellular polysaccharides and DNA, supporting plethora of symbiotic microbial life forms, that can grow on both living and non-living surfaces. These enforced structures are impervious to the drugs and lead to spread of recurrent and non-treatable infections. There is a strong realization among the scientists and healthcare providers to work out alternative strategies to combat the issue of drug resistance and biofilms. Plants are a traditional but rich source of effective antimicrobials with wider spectrum due to presence of multiple constituents in perfect synergy. Other than the biocompatibility and the safety profile, these phytochemicals have been repeatedly proven to overcome the non-responsiveness of resistant microbes and films via multiple pathways such as blocking the efflux pumps, better penetration across the cell membranes or biofilms, and anti-adhesive properties. However, the unfavorable physicochemical attributes and stability issues of these phytochemicals have hampered their commercialization. These issues of the phytochemicals can be solved by designing suitably constructed nanoscaled structures. Nanosized systems can not only improve the physicochemical features of the encapsulated payloads but can also enhance their pharmacokinetic and therapeutic profile. This review encompasses why and how various types of phytochemicals and their nanosized preparations counter the microbial resistance and the biofouling. We believe that phytochemical in tandem with nanotechnological innovations can be employed to defeat the microbial resistance and biofilms. This review will help in better understanding of the challenges associated with developing such platforms and their future prospects.

Green Synthesized Gold Nanoparticles Using Viola betonicifolia Leaves Extract: Characterization, Antimicrobial, Antioxidant, and Cytobiocompatible Activities

Introduction

Viola betonicifolia is a rich source of numerous secondary metabolites, such as alkaloids, flavonoids, tannins, phenolic compounds, saponins, triterpenoids, and so on, that are biologically active towards different potential biomedical applications. To broaden the potential use of Viola betonicifolia in the realm of bionanotechnology, we investigated the plant's ability to synthesize gold nanoparticles (Au NPs) in a green and efficient manner for the very first time.

Methods

The gold nanoparticles (VB-Au NPs) were synthesized using the leaves extract of Viola betonicifolia, in which plant's secondary metabolites function as both reducing and capping agents. The VB-Au NPs were successfully characterized with spectroscopic techniques. The antimicrobial properties of the VB-Au NPs were further explored against bacterial and mycological species. Additionally, their antioxidant, cytotoxic, and cytobiocompatibility properties were examined in vitro against linoleic acid peroxidation, MCF-7 cancer cells, and human mesenchymal stem cells (hMSCs), respectively.

Results

Results demonstrated that VB-Au NPs presented excellent antibacterial, antifungal, and biofilm inhibition performance against all the tested microbial species compared to plant leaves extract and commercially purchased chemically synthesized gold NPs (CH-Au NPs). Moreover, they also exhibited significant antioxidant potential, comparable to the external standard. The VB-Au NPs displayed good cytobiocompatibility with hMSCs and demonstrated excellent cytotoxic potential against MCF-7 cancer cells compared to CH-Au NPs. The current work presents a green method for synthesizing VB-Au NPs with enhanced antioxidant, antimicrobial, cytotoxic and biofilm inhibition efficacy compared to CH-Au NPs might be attributed to the synergistic effect of the nanoparticle's physical properties and the adsorbed biologically active phytomolecules from the plant leaves extract on their surface.

Conclusion

Thus, our study establishes a novel ecologically acceptable route for nanomaterials' fabrication with increased and/or extra medicinal functions derived from their herbal origins.

Photochemical Synthesis of Gold and Silver Nanoparticles-A Review

Nanomaterials have supported important technological advances due to their unique properties and their applicability in various fields, such as biomedicine, catalysis, environment, energy, and electronics. This has triggered a tremendous increase in their demand. In turn, materials scientists have sought facile methods to produce nanomaterials of desired features, i.e., morphology, composition, colloidal stability, and surface chemistry, as these determine the targeted application. The advent of photoprocesses has enabled the easy, fast, scalable, and cost- and energy-effective production of metallic nanoparticles of controlled properties without the use of harmful reagents or sophisticated equipment. Herein, we overview the synthesis of gold and silver nanoparticles via photochemical routes. We extensively discuss the effect of varying the experimental parameters, such as the pH, exposure time, and source of irradiation, the use or not of reductants and surfactants, reagents' nature and concentration, on the outcomes of these noble nanoparticles, namely, their size, shape, and colloidal stability. The hypothetical mechanisms that govern these green processes are discussed whenever available. Finally, we mention their applications and insights for future developments.

Inhibition of microbial growth by silver nanoparticles synthesized from Fraxinus xanthoxyloides leaf extract

AIMS

Conventional antibiotics have been failed to treat infectious diseases due to emergence of multidrug resistance (MDR) in some common pathogens. The current study aimed to formulate new antimicrobials from greener sources. In the midst of these efforts, nanotechnology is a newly emerged field, in which the synthesis of new nanoparticles through novel and efficient means is on the rise.

METHODS AND RESULTS

The current work has been carried out to assess the potential of Fraxinus xanthoxyloides (FX) leaf extract in biosynthesis of silver nanoparticles (FX-AgNPs). This method is economical and simple one-step approach to synthesize AgNPs. Characterization of FX-AgNPs has been done by UV-Visible spectroscopy, scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electronic microscope (TEM) and Fourier transforms infrared spectroscopy (FT-IR). The formation of FX-AgNPs has confirmed through UV-Visible spectroscopy (at 430 nm) by change of colour owing to surface Plasmon resonance. Based on the XRD pattern, the crystalline property of FX-AgNPs has established. Functional groups existing in F. xanthoxyloides leaf extract are confirmed by FT-IR spectrum. SEM and TEM authenticated morphology of the AgNPs. The newly synthesized nanoparticles were evaluated for their antimicrobial potential. Minimum inhibitory concentration was determined against Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA) strains, Pseudomonas aeruginosa and Candida albicans by microtiter plate assay. The lowest inhibition (69%) observed against MRSA was at a concentration of 50 ppm FX-AgNPs and maximum inhibition (81%) observed was against P. aeruginosa. The biosynthesized AgNPs triggered up to 68·6% reduction of the P. aeruginosa biofilm when compared to the control.

CONCLUSION

It can be concluded that nanoparticles could be a better alternative of antibiotics with greater efficacies and represent a valuable milestone to fight against infections caused by MDR pathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study imparts a useful insight into the development of a new antimicrobial agent from a novel source.