Studies with light-triggerable liposomes for the delivery of anti-cancer agents

Thursday, October 11, 2012 — Poster Session III
10:00 a.m. – Noon	Natcher Conference Center, Building 45	NCI	TECH-11

Authors

• J. L. Sine
• A. Yavlovich
• K. Gupta
• M. Viard
• R. Blumenthal
• A. Puri

Abstract

Light-triggerable liposomes present a promising drug delivery platform that relies on strategically designed photo-activable lipids. We have developed liposomes from a diacteylenic phospholipid 1,2 bis(tricosa-10,12-dinoyl)-sn-glycero-3-phosphocholine (DC8,9PC). Liposomes containing calcein (Ex/Em 490/517 nm) in the aqueous compartment and DC8,9PC in the lipid bilayer release solutes in response to light. UV-triggered release is due to photo-crosslinking of the DC8,9PC, but 514 nm-triggered release occurs via a different mechanism. We hypothesize that the photoactivation of the calcein at 514 nm contributes to this observed leakage. We have studied (i) H2O2 production upon light treatment, (ii) effect of addition of H2O2 in the absence of light, and (iii) effect(s) of oxygen radical scavengers on light-triggered release. We report that (i) H2O2 was produced in calcein-loaded liposomes irradiated at 514 nm, (ii) the direct addition of H2O2 did not rupture the liposomes, iii) addition of ascorbic acid (an oxygen radical scavenger) inhibited calcein release in 514 nm laser-treated samples, but sodium azide (which blocks type II photoactivation reaction) had no effect of 514 nm-triggered calcein release. Based on these observations, we propose that visible light-triggered release of entrapped solutes from liposomes involves photo-sensitizer-generated ROS, primarily via a type-I photoactivation process, that perturb the liposome membrane.

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