Enhanced optical breakdown in KB cells labeled with folate-targeted silver-dendrimer composite nanodevices

Enhanced optical breakdown of KB tumor cells folate-targeted with silver-dendrimer composite nanodevices (CNDs) is described. CNDs [(Ag⁰)₂₅-PAMAM_E5.(NH₂)₄₂(NGly)₇₄(NFA)_2.7] were fabricated by reactive encapsulation, using a biocompatible template of dendrimer-folic acid (FA) conjugates. Preferential uptake of the folate-targeted CNDs (of various treatment concentrations and surface functionality) by KB cells was visualized with confocal microscopy and transmission electron microscopy. Intracellular laser-induced optical breakdown threshold and dynamics were detected and characterized by high-frequency ultrasonic monitoring of resulting transient bubble events. When irradiated with a near-infrared, femtosecond laser, the CND-targeted KB cells acted as well-confined activators of laser energy, enhancing nonlinear energy absorption, exhibiting a significant reduction in breakdown threshold and thus selectively promoting intracellular laser-induced optical breakdown. From the Clinical Editor: This study presents a novel method to selectively destroy cancer cells by combining biochemical targeting with topical laser irradiation. A human epidermoid cancer cell line was targeted with folated silver-dendrimer composite nanodevices and the labeled cancer cells were subsequently destroyed by the microbubbles generated due the enhanced energy uptake of the silver nanoparticles from the laser irradiation, as compared to unlabeled cells.