Solid lipid nanoparticles for targeted drug delivery in breast cancer: Biointerface interactions, therapeutic potential, and translational challenges.

Breast cancer (BC) is a significant cancer that is responsible for a huge disease burden globally. Therapeutic effects against BC are often hampered due to poor drug bioavailability, systemic toxicity, and multidrug resistance development. Solid lipid nanoparticles (SLNs) started as advanced lipidic nanocarriers that could offer biocompatibility, physicochemical stability, and controllable interaction with the bio-interface. This review examines the design, functionalization, and therapeutic potentials of SLNs against breast cancer in-depth and critically. The cellular uptake, tumor penetration, intracellular trafficking of drugs, and resulting antitumor activity of SLN formulations, their lipid composition, and surface engineering were discussed. It is noted that SLNs had an improved delivery of anticancer agents, natural compounds, and new genetic payloads thanks to endocytic uptake and intracellular sustained release, while overcoming resistance mechanisms. Apart from monotherapy, SLN-optimized co-delivery systems and multimodal strategies combining photodynamic, photothermal, immunotherapeutic, and gene-modulating methods are highlighted for potential synergistic anticancer efficacy. The interplay of nano-bio interface interactions on a potential product involves an evaluation of toxicity, biodistribution, immunogenicity, scale-up, and regulatory challenges. Ultimately, the discussion revolves around future perspectives that include personalized medicine, AI-assisted formulation optimization, and sustainable manufacturing. Overall, current evidence supports the suitability of SLNs as multifunctional platforms with great potential for improving therapeutic outcomes and advancing precision therapy in breast cancer, although these applications will depend upon further clinical evidence and regulation.