Raman-active polymers for drug-delivery and quantification (Conference Presentation)

Polymer-encapsulation of drugs modulates their delivery: improving solubility and stability; promoting transmembrane transport; extending circulation times; providing selective uptake; and giving a controlled release mechanism. However, understanding the properties of the polymer-delivery system itself in cell and tissue models of disease poses many challenges. We have visualised PLGA particle delivery systems by stimulated Raman scattering (SRS) microscopy, through the use of non-toxic, tuneable labels which vibrate in the cell-silent region. We compared: the loading efficiency of Raman labels; the effect of label incorporation on particle size, solubility and cargo loading capacity; and the stability of Raman-labelled particles to a range of physiological conditions. Using our optimised protocols, we compared the rate of cargo release from PLGA particles composed of different lactide/glycolide monomer ratios, and explored the use of SRS microscopy to quantify particle uptake by RAW 264.7 macrophages, and the rate of intracellular cargo release of Raman-active drugs. This work provides a foundation for a more complete understanding of PLGA-based particle drug delivery systems.