Nanofluid-Enhanced Laser Lithotripsy Using Conducting Polymer Nanoparticles

Abstract

Urinary stone disease, characterized by the formation of hard mineral deposits in the urinary tract, has seen a rising prevalence in the U.S. in recent years. This condition often leads to severe pain and typically requires medical intervention. Laser lithotripsy, a minimally invasive treatment, uses laser energy to fragment urinary stones into smaller pieces, facilitating easier removal or natural passage. Among available laser technologies, the holmium:yttrium-aluminum-garnet (Ho:YAG) laser has established itself as the gold standard over the past three decades. Efforts to improve Ho:YAG laser ablation efficiency have largely focused on adjusting laser parameters such as pulse energy and frequency. In this study, we proposed a nanoplasmonic engineering strategy by incorporating nanoparticles (NPs) with strong near-infrared (NIR) absorption into the fluid surrounding the stone, enhancing the light-matter interaction. Using a 0.03 wt.% PEDOT:PSS nanofluid, stone ablation efficiency improved by 38-727% in spot treatment and 26-75% in scanning treatment with a clinical laser lithotripter. The highly absorbing nanofluid accelerates vapor tunnel formation, boosts laser energy transmission to the stone, and permeates stone pores to enhance damage, without increasing thermal tissue injury risk. Cytotoxicity tests also confirmed minimal toxicity at appropriate concentrations. This nanofluid-based approach offers a promising advancement for more efficient and safer laser lithotripsy.