Photothermal light harvesting and light-gated molecular release by nanoporous gold disks

摘要

Photothermal heating has been an effective mechanism for harvesting light energy by plasmonic resonance. Photothermally generated hyperthermia can alter cell behavior, change cell microenvironment, and promote or suppress cell growth. In the past, colloidal nanoparticles such as gold nanospheres, nanoshells, nanorods, and nanocages have been developed for various applications. Here, we show that nanoporous gold disks (NPGDs) with 400 nm diameter, 75 run thickness, and 13 nm pores exhibit large specific surface area and effective photothermal light harvesting capability. Another potential application is demonstrated by light-gated, multi-step molecular release of pre-adsorbed R6G fluorescent dye on arrayed NPGDs. Through the use of time-resolved temperature mapping, the spatial and temporal characteristics of photothermal heating in NPGD arrays is successfully demonstrated for both aqueous and air ambient environments. By applying a thermodynamic model to our experimental data, we determined the photothermal conversion efficiency at 56% for NPGD arrays. As a potential application, light-gated, multi-stage release of pre-adsorbed R6G dye molecules from NPGD arrays has been demonstrated. The results establish the foundation that NPGDs can be employed for photothermal light harvesting and light-gated molecular release.