Bio-directed synthesis of Pt-nanoparticles from aqueous extract of red algae Halymenia dilatata and their biomedical application

Abstract In this study, the biosynthesis of platinum nanoparticles (Hd-PtNPs) from red algae Halymenia dilatata and its broad spectrum of bioactivities were explored. The synthesized Hd-PtNPs were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HR-TEM), and dynamic light scattering (DLS) analysis. The XRD results showed that the synthesized particles were pure crystalline while the FE-SEM and HR-TEM analysis demonstrated that the Hd-PtNPs were spherical and well-dispersed with an average size of 15 ± 1.7 nm. The zeta potential of Hd-PtNPs was found to be −19.9 mV, which indicates that the synthesized particles were highly stable and well-dispersed. The presence of phytochemical constituents in the H. dilatata aqueous extract performs a capping and reducing process in the Hd-PtNPs formation, which was confirmed by FT-IR analysis. The synthesized Hd-PtNPs showed excellent antioxidant properties in DPPH radical scavenging, reducing power, and total antioxidant assays. Furthermore, the Hd-PtNPs exhibit a strong cytotoxic effect against MDA-MB-231 cancer cell lines (IC50 = 50 μg/mL). Moreover, the Hd-PtNPs showed notable inhibitory activity against Gram-positive (Streptococcus pneumonia) and Gram-negative bacteria (Aeromonas hydrophila). In addition, Hd-PtNPs display less toxicity effect on Artemia nauplii even at a higher concentration corroborating the fact that the synthesized Hd-PtNPs are eco-friendly. Thus, Hd-PtNPs can be used as an alternative source in pharmaceutical and biomedical applications.