Photothermal bubbles as optical scattering probes for imaging living cells

Aims:. We propose and have experimentally studied a new method with improved sensitivity and specificity of imaging of living cells. Method: Intracellular photothermal bubbles generated around gold nanoparticles (NPs) and their clusters were proposed as optical scattering probes for the amplification of scattered light. Results; Microbubbles generated around gold spheres and shells with 10-ns 532-nm laser pulses in individual living cells (leukemia cells, lung and squamous carcinoma cancer cells) have amplified optical side scattering up to 1800-times relative to that of intracellular gold NPs, and without detectable damage to host cells. We explain the discovered optical amplification by the endocytosis-mediated clustering of NPs in cells, and by the selective generation of microbubbles (that do not disrupt the host cell) around these clusters at minimal levels of laser pulse fluence. Conclusions: Photothermal bubbles generated around laser-activated gold NPs may significantly improve the sensitivity and specificity of cell imaging, and can be considered as a new type of optical cellular probes.