Light-induced drug release has been explored as a strategy for externally modulating the release of drug from delivery systems. This study reports the development of a solid lipid nanoparticulate system (SLN) for paclitaxel (PTX), where photosensitizer-mediated oxidation of lipids was used as a mechanism for controlling the drug release. Low-intensity (23 mW/cm2) near-infrared (around 730 nm) illumination was externally applied as the light source. PTX release was less than 10% within 4 h from these SLN and was 8-fold higher after application of light at time zero. The other advantages of this approach include the use of ascorbic acid (ASC) as an antioxidant for enhancing the release and storage stability of the delivery system. Antioxidant like ASC in the SLN decrease the degradation of lipid by 8-fold within 4 months of storage. Presence of ASC and light illumination of SLN containing PTX further decreased the IC50 by 2 times in A549 cells. The uniqueness of this approach allows the possibility of external modulation to achieve pulsatile release from the delivery system. The light used in the NIR spectral range of 700-850 nm, which has the greatest tissue penetration ability, with a low intensity will be safe for normal tissues.
Keywords: Controlled release; anticancer; hydrophobic drugs; lipid nanoparticles; low-intensity light; near-infrared photosensitizer.