Enhanced thermal and magnetic properties of biosynthesized silver nanoparticles for antibacterial efficacy and heavy metal biosensing applications

To develop a cost-effective method of successfully newly fabricated silver nanoparticles from Dieffenbachia seguine aqueous leaves extract which has been proven thermally stable and ferromagnetic behavior. AgNPs were nano structural and morphological examined using several techniques, including ultraviolet-visible, Fourier transform infrared spectroscopy(FTIR), Scanning Electron Microscope(SEM), Energy Dispersive X-ray Spectroscopy(EDS), X-ray diffraction(XRD), and Vibrating Sample Magnetometer (VSM). A peak in absorption was detected at 421.5 nm. The functional groups -OH, -NH2, C O, -COOH were responsible for the reduction and capping of silver nanoparticles, as demonstrated by FTIR. SEM was shown that the high-density synthesized Ag nanoparticles were spherical in shape and the average size of the AgNPs was found to be around 13.66 nm. An elemental analysis of the synthesized sample was conducted via EDS, revealing the exclusive presence of silver with 100% purity by both weight and atomic percentage. XRD confirms the successful formation of crystalline AgNPs with an Face-Centered Cubic (FCC) lattice structure. VSM analysis revealed that the silver nanoparticles display soft ferromagnetic-like behavior at room temperature. Thermogravimetric and differential thermal analysis (TGA/DTA) study demonstrated that AgNPs are thermally stable up to 100°C. AgNPs were specifically able to detect up to Pb 2 + , Zn 2+ , Fe 3+ , Fe 2+ ions, according to biosensing investigations. The nanoparticles showed the highest activity against Enterobacter cloacae (11.0 ± 0.20 mm to 15.6 ± 0.30 mm inhibition zones at concentrations from 50 to 600 µg), followed closely by Pseudomonas aeruginosa (10.8 ± 0.44 mm to 15.5 ± 0.92 mm) and Klebsiella oxytoca (12.1 ± 0.10 mm to 15.1 ± 0.25 mm). Klebsiella oxytoca was particularly susceptible in a concentration-dependent manner. The nanoparticles showed the least activity against Escherichia coli (11.9 ± 0.12–14.2 ± 0.20 mm) and Enterococcus faecalis (11.2 ± 0.10 mm to 14.5 ± 0.40 mm).Additionally, none of the crude extracts demonstrated any antibacterial effect on the pathogenic bacteria. • Successful biosynthesis of silver nanoparticles (AgNPs) using a sustainable, eco-friendly approach. • Developed a sensitive colorimetric/electrochemical biosensing platform for the detection of toxic heavy metals. • Bio-AgNPs exhibited high efficacy against pathogenic bacteria, suggesting potential for clinical or food-safety applications. • Demonstrated significant improvements in both the thermal stability and superparamagnetic behavior of the synthesized AgNPs