SMART Nanocarriers for siRNA Delivery: Stimuli-Responsive Platforms for Targeted Gene Silencing.

Despite the remarkable specificity of small interfering RNA (siRNA)-based treatments for gene silencing, biological limitations like poor stability, rapid systemic clearance, immunogenicity, and inefficient intracellular delivery hinder their clinical translation. A promising strategy for overcoming these challenges and enabling precise, site-specific gene silencing is the use of SMART nanocarriers, including stimuli-responsive, adaptable, and multifunctional delivery platforms. Controlled siRNA release, enhanced cellular uptake, and effective endosomal escape are enabled by these novel nanocarriers' ability to respond dynamically to exogenous triggers such as light, ultrasound, and magnetic fields as well as endogenous stimuli such as pH gradients, redox potential, enzymatic activity, and hypoxia. Recent advances have combined rational material design, surface functionalization with targeted ligands, and modular architectures to gain spatiotemporal control over gene silencing while limiting unintended targets and systemic toxicity. This study examines the critical design concepts, fabrication methodologies, and molecular pathways governing SMART nanocarrier-mediated siRNA distribution, with a focus on polymeric, lipid-based, inorganic, and bioinspired platforms. The article highlights key preclinical and emerging clinical breakthroughs, as well as issues with scalability, repeatability, immunocompatibility, and regulatory translation. This review emphasizes the critical significance of stimulus-responsive nanocarriers in developing siRNA treatments towards precision medicine applications in oncology, neurological disorders, and inflammatory illnesses by consolidating recent studies and future prospects.