Quantitative Evaluation and Optimization of Photothermal Bubble Generation around Overheated Nanoparticles Excited by Pulsed Lasers

Photothermal nanobubble induced by laser-excited plasmonic nanoparticle (NP) presents promising applications in the following fields: optoporation, biosensing, photoacoustics, and theranostics. The diversity of nanoplasmonic systems affects plasmonic response in a highly intricate way and necessitates a systematic design approach based on comprehensive theoretical studies, which currently remains scarce. To palliate this issue, we developed an efficient extended two-temperature model (ETTM). Through a self-built multimodal experimental setup, the photothermal behavior under nanosecond-laser excitation was studied, and the ETTM applicability was further demonstrated. Furthermore, we investigated the photothermal performance of gold NPs excited by pulsed-lasers in the screening of large libraries of excitation wavelength (350-800 nm) and pulse duration (100 fs to 5 ns). Results showed that two prevailing factors were involved in rationalizing photothermal bubble generation in the subnanosecond and nanosecond excitation regimes: the thermo-induced NP melting and the bleaching of localized surface plasmon resonance (LSPR). With considering the NP durability for biosafety, the optimization of the photothermal effect for bubble generation was found to be closely associated with Kapitza conductance, excitation wavelength, and pulse duration. Our study provides a general and quantitative insight on the influence of the nanoplasmonic system on photothermal effect. The simulation-based design guidelines can be broadly used in engineering systems for biological applications.