This study was conducted to identify promising applications of green silver nanoparticles (AgNPs) prepared from a bark extract of Sweetinia mahagoni (Sm). The green synthesized Sm-AgNPs were characterized using various spectroscopy methods. AgNPs were first investigated using ultraviolet–visible spectroscopy, and the metal nanoparticles exhibited an intense surfaceplasmon resonance (SPR) peak at different wavelengths. The green synthesized Sm-AgNPs had an SPR peak at 430 nm, which confirms the formation of Sm-AgNPs. In addition, Fourier transform infrared (FTIR) spectroscopy was conducted to determine the bioactive compounds of bark extract that actively participate in the reduction of Sm-AgNPs, and the results revealed O−H stretching of free hydroxyl alcohol and phenols, N−H bonds of primary amines, S＝O stretching of sulfoxide in aromatic groups, C−I stretching due to aliphatic iodo compounds, and C−Br stretching by halo compounds of the bark extract which might reduce and stabilize Sm-AgNPs. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) results revealed that Sm-AgNPs were approximately irregular spheres. EDS results revealed the complete reduction of silver to elemental silver. The particle size analysis of Sm-AgNPs was conducted using dynamic light scattering (DLS), and the results revealed that Sm-AgNPs were polydisperse with an average size range from 35.8 to 47.8 nm, an average mean size of 41.3 nm, and a Z average of 37.7 nm. Sm-AgNPs had a negative zeta potential value of −19.0 mV, indicating that Sm-AgNPs were very stable in colloidal form. Further studies were carried out to demonstrate their usefulness in industrial and biomedical applications. In these studies, Sm-AgNPs exhibited a very good antibacterial activity against both Gram-negative and Gram-positive bacteria. In addition to regular assays, we also investigated important industrial applications such as the reduction of toxic hexavalent chromium to a nontoxic form and sensing of Hg²⁺ ions. The results revealed that Sm-AgNPs had an excellent performance in biosensor applications such as sensing and detecting mercury at parts per million/parts per billion levels. In conclusion, green Sm-AgNPs are promising materials in therapeutic and industrial applications.

Recent investigations on green synthesis of silver nanoparticles (AgNPs) have been widely used in various therapeutic and industrial applications. So in the present study, AgNPs and PVP coated AgNPs were biosynthesized using fig fruit (Ficus carica) named as FF-AgNPs PVP-FF-AgNPs. The FF-AgNPs and PVP-FF-AgNPs revealed the surface Plasmon resonance band at 446 nm and 460 nm respectively. The FT-IR analysis of both nanoparticles reveals that different bioactive components of the fruit extract were actively involved in reduction of AgNPs. The SEM revealed that the particles are roughly spherical and irregular in shape and size, EDX analysis confirms the formation of complete reduction of silver to elemental silver. DLS studies also revealed similar results with both the nanoparticles are within the range of 10 ± 5 nm to 35 ± 5 nm. The zeta potential studies reveal negative potential values were as follows FF-AgNPs has -13.8 mV and PVP-FF-AgNPs has -17.1 mV. They also exhibit good antimicrobial activity. Another important application of these nanoparticles is dual detection of toxic chromium (Ⅵ) and photocatalytic dye degradation of cotton blue by H₂O₂ quenching and without quenching. It is concluded that, biosynthesized FF-AgNPs and PVP-FF-AgNPs have multiple applications of economic importance and environmental pollution.

Green synthesis of silver nanoparticles (Ag NPs) by both ripe and unripe fruit extract was carried out by an important medicinal plant Tinospora cordifolia. The ripe and unripe fruit extract mediated bio-inspired Ag NPs showed surface plasmon resonance (SPR) band at 431 and 421 nm respectively and confirmed the formation of Tc-Ag NPs. The functional groups of bioactive components of ripe and unripe fruits were identified which reduced silver nitrate to silver ions by Fourier-transform infrared spectroscopy (FTIR). The size distribution of biosynthesized Tc-Ag NPs of ripe and unripe was determined by particle size analyzer which revealed that the Z average of Tc-Ag NPs was around 30-35 nm ± 1 nm and 30-35.8 nm ± 1 nm with an Z average of 25.9 and 28.5 nm respectively. Tc-Ag NPs exhibited stability due to its high negative zeta potential for both ripe and unripe fruit extract mediated Tc-Ag NPs as of -27.2 and -24.6 mV. Tc-Ag NPs were used to evaluate the antibacterial, antioxidant and catalytic activities. The Tc-Ag NPs revealed good antimicrobial activity. Antibiotic erythromycin was used as a standard in the present study. The Tc-Ag NPs of both ripe and unrippen fruits disclosed greater free radical scavenging efficacy which proved to be potent antioxidant agents and also exhibited potential catalytic activity by converting 4 nitro-phenol to 4 amino phenols at rapid pace. It was concluded that the Tc-Ag NPs synthesized by ripe and unripe fruits almost showed similar results, and so both of them proved to have excellent multifunctional biomedical properties.

The use of nanoparticles in treating dreadful diseases like cancer is the emerging field of research in cancer therapy. In the present investigation, the green biosynthesis of silver nanoparticles (AgNPs) with aqueous fruit extract of Terminalia belarica has been carried out, and ultraviolet-visible spectroscopy (UV-Vis) analysis was done which revealed an intense surface plasmon resonance (SPR) band at 430 nm, thus confirming the formation of Tb-AgNPs. The AgNPs were further characterized by Fourier transform-infrared spectroscopy (FTIR), showing the reduction of silver nitrate into Tb-AgNPs by the reduction of different functional groups such as hydroxyl, phenols, stretch of aldehydes, alkenes and aromatics. Transmission electron microscopy (TEM) and diffraction light scattering (DLS) study showed that the nanoparticles were round in shape with an average size of 46.5 nm. The atomic force microscopy (AFM) analysis also revealed similar results to facilitate that the AgNPs were round in shape, and the size was calculated by Z-coloration method. Furthermore, the X-ray diffraction (XRD) data confirmed that Tb-AgNPs were crystalline with face centered cubic (fcc) structure and were very stable with −29.1 mV Zeta potential. Tb-AgNPs showed efficient free radical scavenging activity against 2, 2-diphenyl-1-picrylhydrazyl, hydrogen peroxide and nitric oxide. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method was the best among the three antioxidant methods with the half maximal inhibitory concentration (IC₅₀) value of 47.25 ± 0.17. Tb-AgNPs also showed superior and efficient antibacterial activity greater than the control antibiotic, and showed effective anti-proliferative and cytotoxic effect on human breast cancer cells with IC₅₀ value of 73.18 µg/mL. The biosynthesized Tb-AgNPs with multifunctional properties could be employed as a source for the exploration of novel therapeutic antioxidant, antibacterial and anticancer agent.