Effect of mineral elements on the formation of gallbladder stones using spectroscopic techniques

Long-standing gallbladder stones have been recognized as one of the highest risk factors for gallbladder cancer. However, the growth and progression of gallbladder stones are still not well-known, and their uncovering requires accurate information on the formation/nucleation and complex compositional information of gallstones. Multiple and single gallstones are analyzed using laser-induced breakdown spectroscopy (LIBS), photoacoustic spectroscopy (PAS), and Fourier transform infrared spectroscopy (FTIR). Spectral signatures as well as spatial variation in the spectral intensities of different elements are observed in the LIBS spectra of the gallstones. In the multiple-type gallstones, the concentration of inorganic content increases from core to periphery, whereas a single gallstone shows the opposite trend from the point of nucleation/core. It is suggested that the concentration of inorganic elements (Mg, Ca, K, and Na) plays an important role in the nucleation and growth of gallstones; thus, accordingly, multiple- and single-type gallstones are found in the gallbladder. The presence of different electronic bands of molecules, such as CH, C₂, CN, and NH, is confirmed by LIBS and FTIR. PAS has identified molecules, such as cholesterol, calcium carbonate, and calcium phosphate, in different gallstone samples. These results show that PAS combined with LIBS is a promising candidate for the compositional analysis of gallstones. Furthermore, principal component analysis (PCA) is used to discriminate different layers present in the gallstones.