Lipid Nanostructures for Targeted and Controlled Drug Delivery

Lipid nanostructures have emerged as versatile drug delivery platforms capable of improving drug solubility, protecting therapeutic agents from degradation, modifying pharmacokinetic behaviour, and facilitating targeted delivery. Conventional dosage forms may be associated with poor aqueous solubility, limited bioavailability, rapid drug elimination, nonspecific distribution, and dose-related adverse effects. Lipid-based nanocarriers offer opportunities to overcome several of these limitations through the encapsulation or association of therapeutic molecules within organized lipid matrices or vesicular structures. Major systems include liposomes, solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), lipid nanoparticles (LNPs), and liquid-crystalline lipid nanocarriers. Their physicochemical properties can be adjusted through lipid composition, particle size, surface charge, surfactant selection, and surface functionalization. Targeted delivery can be achieved through passive accumulation, ligand–receptor interactions, and tissue-specific formulation strategies, whereas controlled drug release can be regulated through matrix composition, drug–lipid interactions, diffusion, degradation, and stimuli-responsive mechanisms. These systems have demonstrated potential in cancer therapy, nucleic acid delivery, infectious diseases, neurological disorders, and topical and ocular drug delivery. Nevertheless, challenges involving colloidal stability, drug loading, biological variability, toxicity, manufacturing scale-up, reproducibility, and regulatory characterization continue to restrict broader clinical translation. This review discusses the principal lipid nanostructures, their formulation and characterization, mechanisms of targeting and controlled release, therapeutic applications, and emerging developments in precision nanomedicine.