Green synthesis of metal nanoparticles using <i>Cinnamomum</i>-based extracts and their applications

<p dir="ltr"><b>Introduction:</b> Nanotechnology is the science that deals with matter on the nanoscale, with sizes ranging from 1 to 100 nm. It involves designing, synthesising, characterising and applying these nanoscale materials. Nanoparticles (NPs) are known for their high surface-area to volume-ratio, surface charge density, low melting point, and distinguishably good optical/electrical properties. NPs exhibit an excellent drug delivery system, an effective contrast agent for vascular imaging, and effective antimicrobial activity. The biological synthesis of NPs is a simple, cost-effective, and environmentally friendly technique. This bottom-up technique utilises organisms' enzymes/bio-compounds and a plant extract as capping and reducing agents. <i>Cinnamomum</i> species are known for their intrinsic antimicrobial, antidiabetic, antioxidant, anti-inflammatory, anticancer, and neuroprotective properties. This review summarises articles that greenly synthesised NPs using <i>Cinnamomum</i> species' extracts, describing their methodologies, characterisation of the nanoparticles and their medical applications. <p dir="ltr"><b>Methods:</b> A literature search has been conducted on databases PubMed, ScienceDirect, and Frontier on the green synthesis of metal nanoparticles (MNPs) using <i>Cinnamomum</i>-based extracts. Various articles reported the methodology of utilising <i>Cinnamomum</i> species' extracts as reducing and capping agents. Only original lab articles were considered. <p dir="ltr"><b>Results:</b> Various types of MNPs have been successfully synthesised. The most common <i>Cinnamomum</i> species utilised as extracts is <i>Cinnamomum tamala</i>. The most common applications tested were the MNPs' antibacterial, antiviral, antifungal, antidiabetic and anticancerous activity. MNPs also had a role in treating mice-induced polycystic ovarian syndrome and Parkinson-like neurodegenerative diseases. <p dir="ltr"><b>Conclusion:</b> <i>Cinnamomum</i> species have been successfully utilised in the green synthesis of various MNPs. Silver and Gold NPs were the most reported. These MNPs proved their efficacy in multiple fields of medicine and biology, especially their antibacterial, antiviral and antifungal activity. Notably, the newly synthesised NPs showed promising results in treating polycystic ovarian syndrome in rats.