Feasibility of laser-induced breakdown spectroscopy as a direct raw bile analysis tool for screening of gallbladder cancer

Abstract

Laser-induced breakdown spectroscopy (LIBS) was explored for the first time for discrimination of gallbladder (GB) polyp and GB cancer (GBC) by direct measurement of raw bile juice without pretreatment. Initially, for reproducible LIBS measurement, a laser-patterned silicon wafer (LPSW) incorporating 40 x 40 crossed trenches in an area of 1 x 1 cm(2) was used to spread bile juice as homogeneous as possible over the surface without substantial localization, and LiCl was employed as an internal standard. Mg, Ca, Na, and K peaks were dominant in the spectra of raw bile samples, with lower peak areas in cases of GBC. The lower elemental concentrations in GBC samples probably result from dilution of bile by a degraded water absorption ability of the thickened GB wall due to cancer and carcinogenesis. In particular, the Mg and K peak intensities were further lower and improved discrimination of GBC against normal/GB polyp. Moreover, discrimination was distinct when using the ratio of Na and K peak areas. Misbalancing of Na and K in cell metabolism induced by cancer progression was presumed to be the origin of enhanced discrimination. Overall, the LIBS-based direct bile analysis scheme is a simple and potential tool for screening of GBC.