Purpose: Poly(lactic-co -glycolic acid) (PLGA) is widely used for drug delivery because of its biocompatibility, ability to solubilize a wide variety of drugs, and tunable degradation. However, achieving sub-100 nm nanoparticles (NPs), as might be desired for delivery via the enhanced permeability and retention effect, is extremely difficult via typical top-down emulsion approaches.
Methods: Here, we present a bottom-up synthesis method yielding PLGA/block copolymer hybrids (ie, “PolyDots”), consisting of hydrophobic PLGA chains entrapped within self-assembling poly(styrene-b -ethylene oxide) (PS-b -PEO) micelles.
Results: PolyDots exhibit average diameters <50 nm and lower polydispersity than conventional PLGA NPs. Drug encapsulation efficiencies of PolyDots match conventional PLGA NPs (ie, ~30%) and are greater than those obtained from PS-b -PEO micelles (ie, ~7%). Increasing the PLGA:PS-b -PEO weight ratio alters the drug release mechanism from chain relaxation to erosion controlled. PolyDots are taken up by model glioma cells via endocytotic mechanisms within 24 hours, providing a potential means for delivery to cytoplasm. PolyDots can be lyophilized with minimal change in morphology and encapsulant functionality, and can be produced at scale using electrospray.
Conclusion: Encapsulation of PLGA within micelles provides a bottom-up route for the synthesis of sub-100 nm PLGA-based nanocarriers with enhanced stability and drug-loading capacity, and tunable drug release, suitable for potential clinical applications.
Keywords: PLGA, nanoparticles, micelles, drug delivery, hydrophobic drug, block copolymer, glioma, electrospray