Effects of arginine-based surface modifications of liposomes for drug delivery in Caco-2 colon carcinoma cells

Liposomal encapsulation of chemotherapeutics improves circulation time and decreases off-target effects through the enhanced permeability and retention (EPR) effect. Improving the efficacy of these drug carriers through surface modification could benefit patients. A library of arginine derivatives was conjugated to liposomes through carbodiimide chemistry. Both unmodified and modified liposomes were loaded with doxorubicin and exposed to Caco-2 colon carcinoma cells to measure the half maximal inhibitory concentration (IC50). Most of the modifications improved the toxicity of doxorubicin. Principal component analysis (PCA) was used to uncover correlations between physicochemical properties (lipophilicity (log P), partition coefficient (log D), number of hydrogen bond donors, number of hydrogen bond acceptors, freely rotating bonds, surface tension, polarization surface area, and isoelectric point) and the IC50 of encapsulated doxorubicin. Generalized rules for improved toxicity were also developed, which stated that improved drug carriers should have at least 4 hydrogen bond donors, between 4 and 6 freely rotating bonds, an isoelectric point above 5.5, and a log P between -2 and -1. Using these relationships along with previously obtained correlations for macrophages, selective targeting and the understanding of how to rationally design such drug carriers can be improved.