Biochemical Approaches to Enhance Drug Bioavailability via Nanocarrier Systems

Background: Poor drug bioavailability remains a major obstacle in therapeutic efficacy, particularly for hydrophobic compounds, macromolecules, and agents with narrow absorption windows or rapid degradation. Nanocarrier systems—such as liposomes, polymeric nanoparticles, solid lipid nanoparticles, dendrimers, and micelles—have emerged as transformative platforms to overcome these limitations. These carriers enhance solubility, prolong circulation time, enable targeted delivery, and modulate drug release kinetics, thereby improving pharmacokinetics and biodistribution. Methods and Results: This review focuses on the biochemical principles underpinning nanocarrier-based enhancement of drug bioavailability and evaluates key advances in design, functionalization, and in vivo performance. Critical parameters include surface chemistry, particle size, zeta potential, and ligand conjugation, which influence interactions with biological barriers such as mucosa, plasma proteins, and cellular membranes. Functionalized nanocarriers employing PEGylation, pH-sensitive moieties, and targeting ligands (e.g., antibodies, peptides, aptamers) demonstrate improved tissue specificity and cellular uptake through receptor-mediated endocytosis. Enzyme-responsive and redox-sensitive systems further allow site-specific release in pathological microenvironments. Case studies include enhanced oral absorption of poorly soluble drugs, improved brain penetration for neurotherapeutics, and tumor-selective accumulation in oncology. Challenges such as nanoparticle stability, immune clearance, and manufacturing scalability are also addressed. Conclusion: Biochemically optimized nanocarrier systems represent a powerful approach to improve the bioavailability of diverse therapeutics.