Solid Lipid Nanoparticles As A Versatile Platform For Targeted And Controlled Drug Delivery

Solid lipid nanoparticles (SLNs) have emerged as a versatile nanocarrier platform for the targeted and controlled
delivery of therapeutic agents. Comprising physiological lipids stabilized by surfactants, SLNs combine the advantages
of conventional colloidal carriers such as liposomes and polymeric nanoparticles while overcoming their limitations
related to stability, scalability, and toxicity. These submicron particles, typically in the range of 50–1000 nm, possess
a solid lipid matrix at body temperature, enabling high drug encapsulation efficiency, controlled release, and protection
of labile molecules against chemical degradation. Recent advances in SLN technology include surface modification for
active targeting, hybrid systems incorporating polymers, and stimuli-responsive formulations triggered by pH,
temperature, or enzymatic activity. SLNs have been successfully explored for oral, parenteral, pulmonary, ocular, and
transdermal delivery of small molecules, peptides, proteins, and nucleic acids. Challenges such as limited drug loading,
burst release, and lipid polymorphism remain, but emerging strategies such as nanostructured lipid carriers (NLCs),
combinatorial lipid–polymer hybrids, and green manufacturing techniques are expanding their potential. This review
provides a comprehensive overview of SLN design, formulation considerations, applications in targeted and controlled
drug delivery, and future directions aimed at clinical translation.