Applications of Natural and Synthetic Polymeric Nanocarriers in Modern Drug Delivery

Nanomedicine has transformed modern therapeutics by enabling precise and efficient drug delivery, with polymer-based nanoparticles emerging as versatile carriers. Natural polymers such as alginate, chitosan, gelatin, pullulan, and gliadin offer biocompatibility, biodegradability, sand low toxicity, making them attractive for pharmaceutical applications. However, their batch variability and unpredictable physicochemical behavior sometimes limit performance. Synthetic polymers, including polylactide (PLA), polylactide-co-glycolide (PLGA), polyanhydrides, poly-ε-caprolactone, and polyalkyl cyanoacrylates, provide superior structural uniformity and tunable degradation profiles, enabling controlled and targeted drug release. Both natural and synthetic polymers have demonstrated success in enhancing solubility, bioavailability, and therapeutic efficacy while minimizing systemic side effects. This review highlights the comparative advantages, limitations, and applications of polymeric nanoparticles in areas such as cancer therapy, ocular delivery, blood-brain barrier penetration, vaccination, and gene therapy. The integration of natural and synthetic polymers holds promise for designing next-generation nanocarriers tailored to complex clinical challenges.