In this work, we present a refined analytical platform that combines gold nanoparticles (Au NPs) synthesized by pulsed laser ablation in liquid (PLAL) with acoustic levitation to enable in situ Laser-Induced Breakdown Spectroscopy (LIBS) measurements from Au NP–containing droplets. The spatial positioning of the droplet relative to the laser focal spot was systematically optimized, identifying an optimal location along the laser propagation axis that maximizes emission intensity and measurement reproducibility. The pre-concentration factor (P·F) was studied by independently varying the initial levitated volume and the final evaporated volume while maintaining defined droplet dimensions. The effects of single-shot LIBS laser energy and Au colloid concentration on signal intensity and stability were also thoroughly investigated. The synthesized Au NPs were extensively characterized using various characterization techniques, including Zeta potential, Dynamic Light Scattering (DLS), UV–Vis Spectroscopy, and Transmission Electron Microscopy (TEM) whose results are also presented. In addition, the influence of ambient variables such as temperature and humidity on signal stability was examined. Overall, this study demonstrates that careful adjustment and combination of spatial and physical parameters lead to a pronounced enhancement in LIBS signal, establishing a contactless and sensitive approach suitable for future analytical and biosensing applications. • First LIBS study on acoustically levitated PLAL-synthesized gold nanoparticle droplets. • Systematic tuning of droplet position, pre-concentration, laser energy, and colloid density, resulting in improvement of LIBS signal. • Precise droplet-plasma alignment identified as the most critical factor for improving emission intensity and reproducibility. • IR-assisted preconcentration method achieved controlled volume reduction without inducing nanoparticle melting, aggregation, or morphological alteration. • Establishment of a stable, contactless platform suitable for future nano-enabled biosensing in levitated droplets.
Sreekala et al. (Sun,) studied this question.