Retraction for RSC Advances: Laser-induced gold/chitosan nanocomposites with tailored wettability applied to multi-irradiated microfluidic channels

The controlled wettability of gold nanocomposite surfaces obtained by laser irradiation is introduced. Starting from the conception of materials with controlled surface properties, we describe all the different steps to generate the gold functionalized nanocomposite material and illustrate its surface wettability. Photopatterned gold polymeric films are performed in order to exhibit a remarkable decrease in their wettability when UV laser light irradiation is applied. This process is totally controlled by means of laser texturing allowing the generation of localized areas with tunable wettability by controlling accurately the laser irradiation time. This new technique named laser texturing on gold nanocomposite materials (LTGNM) is applied on chitosan (CTO) polymer with a gold precursor (HAuCl4) suitable for the proposed LTGNM approach. The introduction of a formation mechanism of gold particles is formulated and corroborated by preliminary experimental observations. The control of the irradiation times participates and proves the fragmentation process of the gold nanoparticles (Au-NPs). This new ability of gold nanocomposite material (GNM) provides new potential applications and a possible upscaling in microfluidics and in particular in lab on chip devices for liquid spreading or drugs transports. A microfluidic device based on the control of laser textured CTO-Au surface is proposed. In particular we propose an innovative microfluidic channel constituted by different spatial steps with modified contact angle regions for liquid spreading.