The Antioxidant and In Vitro Wound Healing Activity of Cotyledon orbiculata Aqueous Extract and the Synthesized Biogenic Silver Nanoparticles

Superior In Vivo Wound-Healing Activity of Biosynthesized Silver Nanoparticles with Nepeta cataria (Catnip) on Excision Wound Model in Rat

Silver nanoparticles were biosynthesized with Nepeta cataria plant extract. It was determined that the synthesized Nc-AgNPs gave a strong absorbance peak at 438 nm wavelength in the UV-vis spectrophotometer. SEM and TEM analyses of Nc-AgNPs showed that the synthesized nanoparticles had a spherical morphology. Based on XRD analysis, the average crystallite size of Nc-AgNPs was calculated at 15.74 nm. At the same time, EDS spectrum analysis exhibited dominant emission energy at 3 keV, indicative of Nc-AgNPs. Nc-AgNPs showed an inhibition zone of 12 nm in gram-negative Escherichia coli, 10 nm in gram-positive Enterococcus faecalis, and 11 nm in Staphylococcus aureus. Nc-AgNPs showed high antioxidant properties, with 63% at 5000 μg/mL. The wound-healing properties of Nc-AgNPs were evaluated in vivo in wound models created in a total of 20 Wistar albino male rats, divided into four groups. After 10 days of treatment, the highest wound closure rate was seen in the Nc-AgNP + Vaseline (Group IV) treatment group, at 94%. It was observed that Nc-AgNP + Vaseline nanoformulation significantly increased wound healing, similar to Silverdin®, and Vaseline alone supported healing but did not result in complete closure. Histopathological examination revealed an increase in mature Type 1 collagen in Group IV and positive control (Group II), with better collagen maturation in vehicle control (Group III) compared to negative control (Group I). Immunohistochemical analysis showed complete epithelialization in Group IV and Group II, with distinct cytokeratin expressions, while Group III exhibited mild expressions.

Hybrid Materials Obtained by Immobilization of Biosynthesized Ag Nanoparticles with Antioxidant and Antimicrobial Activity

Ag nanoparticles (AgNPs) were biosynthesized using sage (Salvia officinalis L.) extract. The obtained nanoparticles were supported on SBA-15 mesoporous silica (S), before and after immobilization of 10% TiO2 (Degussa-P25, STp; commercial rutile, STr; and silica synthesized from Ti butoxide, STb). The formation of AgNPs was confirmed by X-ray diffraction. The plasmon resonance effect, evidenced by UV-Vis spectra, was preserved after immobilization only for the sample supported on STb. The immobilization and dispersion properties of AgNPs on supports were evidenced by TEM microscopy, energy-dispersive X-rays, dynamic light scattering, photoluminescence and FT-IR spectroscopy. The antioxidant activity of the supported samples significantly exceeded that of the sage extract or AgNPs. Antimicrobial tests were carried out, in conditions of darkness and white light, on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Higher antimicrobial activity was evident for SAg and STbAg samples. White light increased antibacterial activity in the case of Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). In the first case, antibacterial activity increased for both supported and unsupported AgNPs, while in the second one, the activity increased only for SAg and STbAg samples. The proposed antibacterial mechanism shows the effect of AgNPs and Ag+ ions on bacteria in dark and light conditions.

Green Synthesis of Narrow-Size Silver Nanoparticles Using Ginkgo biloba Leaves: Condition Optimization, Characterization, and Antibacterial and Cytotoxic Activities

Natural products derived from medicinal plants offer convenience and therapeutic potential and have inspired the development of antimicrobial agents. Thus, it is worth exploring the combination of nanotechnology and natural products. In this study, silver nanoparticles (AgNPs) were synthesized from the leaf extract of Ginkgo biloba (Gb), having abundant flavonoid compounds. The reaction conditions and the colloidal stability were assessed using ultraviolet-visible spectroscopy. X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy (FTIR) were used to characterize the AgNPs. AgNPs exhibited a spherical morphology, uniform dispersion, and diameter ranging from ~8 to 9 nm. The FTIR data indicated that phytoconstituents, such as polyphenols, flavonoids, and terpenoids, could potentially serve as reducing and capping agents. The antibacterial activity of the synthesized AgNPs was assessed using broth dilution and agar well diffusion assays. The results demonstrate antibacterial effects against both Gram-positive and Gram-negative strains at low AgNP concentrations. The cytotoxicity of AgNPs was examined in vitro using the CCK-8 method, which showed that low concentrations of AgNPs are noncytotoxic to normal cells and promote cell growth. In conclusion, an environmentally friendly approach for synthesizing AgNPs from Gb leaves yielded antibacterial AgNPs with minimal toxicity, holding promise for future applications in the field of biomedicine.

The Cytotoxicity of Cotyledon orbiculata Aqueous Extract and the Biogenic Silver Nanoparticles Derived from the Extract

Green synthesized silver nanoparticles (AgNPs) have become popular because of their promising biological activities. However, for most of these nanoparticles, the cytotoxic effects have not been determined and their safety is not guaranteed. In a previous study, we successfully synthesized AgNPs (Cotyledon-AgNPs) using an extract of Cotyledon orbiculata, a medicinal plant traditionally used in South Africa to treat skin conditions. Cotyledon-AgNPs were shown to have significant antimicrobial and wound-healing activities. Fibroblast cells treated with extracts of C. orbiculata and Cotyledon-AgNPs demonstrated an enhanced growth rate, which is essential in wound healing. These nanoparticles therefore have promising wound-healing activities. However, the cytotoxicity of these nanoparticles is not known. In this study, the toxic effects of C. orbiculata extract and Cotyledon-AgNPs on the non-cancerous skin fibroblast (KMST-6) were determined using in vitro assays to assess oxidative stress and cell death. Both the C. orbiculata extract and the Cotyledon-AgNPs did not show any significant cytotoxic effects in these assays. Gene expression analysis was also used to assess the cytotoxic effects of Cotyledon-AgNPs at a molecular level. Of the eighty-four molecular toxicity genes analysed, only eight (FASN, SREBF1, CPT2, ASB1, HSPA1B, ABCC2, CASP9, and MKI67) were differentially expressed. These genes are mainly involved in fatty acid and mitochondrial energy metabolism. The results support the finding that Cotyledon-AgNPs have low cytotoxicity at the concentrations tested. The upregulation of genes such as FASN, SERBF1, and MKI-67 also support previous findings that Cotyledon-AgNPs can promote wound healing via cell growth and proliferation. It can therefore be concluded that Cotyledon-AgNPs are not toxic to skin fibroblast cells at the concentration that promotes wound healing. These nanoparticles could possibly be safely used for wound healing.