Advancing Biosensing Frontiers Through Gold Nanoparticle Engineering: Synthesis Strategies and Detection Paradigms

Gold Nanoparticles (GNPs) play a pivotal role in nanobiotechnology because of their distinct physicochemical traits, such as optical properties, compatibility with biological systems, and their ability to be easily functionalized. The top-down and bottom-up approaches are for the synthesis of GNPs. There are various chemical, physical, and green synthesis techniques, such as chemical reduction, seed-mediated growth, physical ablation method, pyrolysis, sputtering, etc. are some methods for the synthesis of GNPs. The use of plants, algae, fungi, and other microorganisms has recently arisen as a new approach for the eco-friendly synthesis with precise control over NP size, shape, and surface properties. The functionalization strategies involving biomolecules, polymers, and ligands enhance their stability and target specificity, facilitating their integration into biosensors. The detection of biomolecules, pathogens, and environmental toxins with high sensitivity and accuracy is facilitated by multiple signals such as localized surface plasmon resonance (LSPR), alterations in color, and electrochemical characteristics. Furthermore, their role in point-of-care diagnostics, drug delivery, and imaging underscores their versatility in biomedical applications. This review provides a comprehensive overview of recent advancements in the synthesis, functionalization, and GNPs-based biosensors. In addition, the review highlights recent advancements, challenges, and future prospects of GNPs in biosensing and nanomedicine, offering an understanding of diagnostics and therapeutic monitoring. The key challenges include stability, reproducibility, and scalability, and the future focuses on green synthesis with enhanced sensitivity and multiplexed biosensing applications.