SOLID LIPID NANOPARTICLES: AN EMERGING PLATFORM FOR TARGETED DRUG DELIVERY AND BIOMEDICAL APPLICATIONS – A COMPREHENSIVE REVIEW

Jitendra Pratap Singh*, Rishabh Maurya, Tanushree Agnihotri

ABSTRACT

Solid Lipid Nanoparticles (SLNs) have emerged as a promising class of lipid-based nanocarriers for improving the delivery of therapeutic agents. Conventional drug delivery systems frequently encounter challenges such as poor aqueous solubility, low bioavailability, rapid degradation, and lack of site-specific targeting, which can compromise therapeutic efficacy. SLNs were developed to address these limitations by combining the advantages of traditional colloidal carriers with the safety and biocompatibility of physiological lipids. These nanoparticles are composed of solid lipids stabilized by surfactants and remain solid at both room and physiological temperatures, enabling efficient drug encapsulation and controlled release. The unique structural characteristics of SLNs facilitate enhanced drug stability, protection from chemical and enzymatic degradation, improved pharmacokinetic behavior, and reduced systemic toxicity. Various preparation methods, including high-pressure homogenization, microemulsion techniques, solvent emulsification, and ultrasonication, have been successfully employed to produce SLNs with desirable physicochemical properties. Comprehensive characterization using particle size analysis, zeta potential measurement, electron microscopy, differential scanning calorimetry, and X-ray diffraction is essential for ensuring formulation quality and stability. Owing to their versatility, SLNs have been extensively investigated for oral, topical, transdermal, ocular, pulmonary, parenteral, and brain-targeted drug delivery. Furthermore, they have demonstrated considerable potential in cancer therapy and the delivery of natural bioactive compounds. Despite certain limitations, including restricted drug-loading capacity and polymorphic transitions during storage, continuous advancements in formulation strategies and surface engineering have significantly expanded their therapeutic applications. This review summarizes the composition, preparation methods, characterization techniques, drug incorporation models, applications, advantages, limitations, and future prospects of SLNs, highlighting their growing importance in modern pharmaceutical and biomedical research.

Keywords: Solid lipid nanoparticles, lipid-based nanocarriers, controlled drug delivery, bioavailability enhancement, targeted drug delivery, nanotechnology, pharmaceutical applications.