Targeted drug delivery: designing nanocarriers for improved therapeutic action

Nanocarriers are fundamentally transforming targeted drug delivery (TDD) by addressing the major limitations of conventional therapies, such as systemic toxicity and poor drug localization. These nanoscopic vehicles, including liposomes and polymeric nanoparticles, typically sized between 1 and 100 nanometers, are engineered to encapsulate, protect, and escort therapeutic agents until they reach the precise site of action. The key to their success lies in targeted delivery mechanisms. Passive targeting utilizes the enhanced permeability and retention (EPR) effect, where nanocarriers accumulate preferentially in leaky tumor vasculature. Active targeting involves surface modification with specific ligands (e.g., functional chemical/group, antibodies, or peptides) that bind to overexpressed receptors on diseased cells, ensuring high local drug concentration. This precision significantly boosts therapeutic efficacy while minimally affecting healthy tissues, leading to fewer side effects. This review provides an in-depth examination of TDD, highlighting how nanocarriers are essential in achieving precision and improving therapeutic outcomes. It explores the diverse strategies and suitable materials utilized to guide therapeutic agents specifically to disease sites while minimizing systemic toxicity.