Imaging the Pore Structure in Geomaterials Using Rhodamine B Covalently Decorated Magnetic Nanoparticles

There has been a recent booming development of multifunctional nanoparticles with precisely defined materials and an accompanying abundance of synthesis methods. However, developing a rational strategy to choose the proper nanoparticle and optimal synthesis method for geological applications remains a bottleneck. Here, a rhodamine B covalently decorated Fe3O4 nanoparticle was studied to assess its application as a novel bifunctional nanomarker for the optical imaging of the pore structure in geomaterials. With this bifunctional nanomarker, we were able to combine magnetic injection, which provides a simple and non-destructive way of introducing the nanomarker into rocks, with fluorescence imaging techniques, which provide clear contrast imaging between geomaterials (black) and porosity (bright). The covalent bifunctional nanomarker exhibits higher fluorescence and less leakage of the fluorescence dye than those produced by the physical coating method. It offers not only a more practical and reliable nanomarker for the analysis of the pore structure in geomaterials but also contributes to nanomaterial-oriented research for various geological applications.