Revisiting gallbladder stones structure through integrated multiscale physicochemical characterization

Abstract

Gallstones are complex biominerals formed through physicochemical, metabolic, and microbial processes. In this study, gallstones were comprehensively characterized, revealing a complex elemental profile comprising C, N, O, Mg, Al, Si, P, S, Ca, Cu, Mn, Fe, Co, Zn, and Cd. The characterization integrated scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX), atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), electron paramagnetic resonance (EPR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and thermal analysis. A diverse, heterogeneously distributed trace metal profile was observed, with potential surface enrichment. XRD, FTIR, thermal analysis and Raman spectroscopy confirmed a cholesterol-dominant mineralogy with mixed anhydrous and monohydrate polymorphs, while SEM–EDX revealed heterogeneous spatial distribution of both major and trace elements. EPR analysis reveals Mn 2+ ions in heterogeneous coordination environments within the gallstone matrix, while complementary analyses identified potential oxygen-donor ligands that may contribute to Mn 2+ coordination. XPS revealed hydrophobic organic domains and coexisting oxidized functional groups at the surface. Collectively, these analyses reveal substantial chemical, structural, elemental, and surface heterogeneity, highlighting the value of integrating bulk and surface-sensitive techniques. These physicochemical features provide a basis for hypotheses regarding biological interactions, including microbial adhesion, which require experimental validation.