pH-Responsive doxorubicin delivery using shear-thinning biomaterials for localized melanoma treatment

Injectable shear-thinning biomaterials (STBs) have attracted significant attention because of their efficient and localized delivery of cells as well as various molecules ranging from growth factors to drugs. Recently, electrostatic interaction-based STBs, including gelatin/LAPONITE (R) nanocomposites, have been developed through a simple assembly process and show outstanding shear-thinning properties and injectability. However, the ability of different compositions of gelatin and LAPONITE (R) to modulate doxorubicin (DOX) delivery at different pH values to enhance the effectiveness of topical skin cancer treatment is still unclear. Here, we fabricated injectable STBs using gelatin and LAPONITE (R) to investigate the influence of LAPONITE (R)/gelatin ratio on mechanical characteristics, capacity for DOX release in response to different pH values, and cytotoxicity toward malignant melanoma. The release profile analysis of various compositions of DOX-loaded STBs under different pH conditions revealed that lower amounts of LAPONITE (R) (6NC25) led to higher pH-responsiveness capable of achieving a localized, controlled, and sustained release of DOX in an acidic tumor microenvironment. Moreover, we showed that 6NC25 had a lower storage modulus and required lower injection forces compared to those with higher LAPONITE (R) ratios. Furthermore, DOX delivery analysis in vitro and in vivo demonstrated that DOX-loaded 6NC25 could efficiently target subcutaneous malignant tumors via DOX-induced cell death and growth restriction.