Tailoring Metal Nanoparticles: A Comparative Assessment of Au, Ag, Cu, Zn, Pt, and Fe for Targeted Applications

Metal nanoparticles (MNPs) represent a class of highly versatile materials distinguished by their tuneable physicochemical properties, including a high surface-to-volume ratio, quantum size effects, and localized surface plasmon resonance (SPR). This review provides a comprehensive comparative analysis of gold (Au), silver (Ag), copper (Cu), zinc (Zn), platinum (Pt), and iron (Fe) nanoparticles, detailing their inherent physicochemical attributes, diverse synthesis methodologies, and wide-ranging applications. Au and Ag nanoparticles exhibit prominent optical properties attributed to SPR, rendering them invaluable for advanced biomedical imaging and targeted drug delivery systems. Conversely, Pt and Zn nanoparticles demonstrate superior catalytic and photocatalytic efficiencies, while Fe nanoparticles possess robust superparamagnetic behavior, enabling their utility in magnetic hyperthermia and environmental remediation. Although cost-effective, Cu and Zn nanoparticles are susceptible to oxidation, necessitating surface passivation strategies for enhanced long-term stability. A variety of synthesis approaches, including physical techniques (e.g., laser ablation, sputtering), chemical reduction methods, and environmentally benign green synthesis (e.g., plant extracts, microorganisms), are critically evaluated for their impact on purity, scalability, and ecological footprint. Physical methods yield high-purity nanoparticles but incur substantial costs. Chemical methods offer precise control over particle size and morphology, albeit often involving hazardous reagents. Green synthesis presents a sustainable alternative, though challenges in reproducibility and large-scale manufacturing persist. In terms of application, Au and Ag largely dominate the biomedical sector; Pt and Zn are extensively employed in catalysis and energy storage; and Fe and Cu are prominent in environmental remediation and magnetic applications. This review identifies current trends, persistent challenges, and future research directions, underscoring the critical need for advancements in MNP stability, scalable green synthesis protocols, and the development of multifunctional nanoparticle systems to optimize performance across various scientific and technological domains.