Journal of Analytical Atomic Spectrometry;
OCT 1 2019.
Citações Web of Science:
This paper describes the possibility of controlling and reducing the laser energy density of nanosecond 193 nm laser radiation in order to selectively ablate biological material from a glass substrate for LA-ICP-MS bioimaging applications. Atomic force microscopy and optical profilometry were used to study the shape of single-shot craters in dried gelatin droplets, ablated at low energy (<500 mJ cm(-2)). These craters were characterized by straight walls and a `flat bottom'. Based on the ablated volume per pulse and corresponding ablation depth, the ablation threshold of the dried gelatin material was estimated at 44 mJ cm(-2) by relying on the Beer model derived from the Beer-Lambert law. Three different glass substrates, i.e. a microscope slide and coverslip of soda-lime-silica (SLS) glass with a slightly different bulk elemental composition and a borosilicate glass coverslip, were ablated using laser energy densities ranging from 150-730 mJ cm(-2) and typical instrument settings applied during LA-ICP-MS bioimaging. The signal intensity of Si-29, a minor isotope of Si which is a major matrix component of the glass surface, was monitored as a measure of material removal and was used to estimate ablation thresholds for the three glass substrates at 262, 181 and 104 mJ cm(-2), respectively. As a proof-of-concept, kidney tissue mounted onto a SLS glass microscope slide substrate and MDA-MB-231 tumor cells seeded on a SLS glass coverslip were selectively ablated by controlling the laser energy density to ensure soft ablation of the glass substrate, but provide hard ablation of the biological material. (AU)