Polymeric nanoparticles for controlled release of herbal actives: A Review

Polymeric nanoparticles (PNPs) are an increasingly important platform to deliver bioactive phytochemicals from traditional and herbal medicines. Nanosizing and polymeric encapsulation improve the aqueous solubility, chemical stability, and oral or topical bioavailability of poorly soluble natural products while enabling sustained and stimulus-responsive release profiles. This review summarizes fabrication strategies for herbal-actives-loaded PNPs (emulsion–diffusion, nanoprecipitation, ionic gelation, polyelectrolyte complexation), highlights commonly used synthetic and natural polymers (PLGA, PLA, PCL, chitosan, alginate), and compares design choices for oral, topical, and parenteral delivery. We synthesize recent in vitro and in vivo evidence for improved pharmacokinetics and therapeutic outcomes – with curcumin, berberine, and other phytoconstituents as paradigmatic examples – and examine applications in wound healing, anti-inflammatory therapy, cancer adjuvant therapy, and antimicrobial uses. Critical issues – scalable manufacturing, reproducibility, batch-to-batch variability of herbal extracts, toxicity, and regulatory pathways – are discussed. Finally, we propose best-practice guidelines for characterization (size, zeta potential, release kinetics), preclinical testing, and a translational roadmap to clinic. The review concludes by identifying knowledge gaps and future directions where PNPs can responsibly modernize herbal therapeutics.