Fluorescent nanoparticles light up rocks’ pores

Abstract

A team of researchers has developed a simple, robust method for imaging the pores in rocks using magnetic, fluorescent nanoparticles (ACS Earth Space Chem. 2019, DOI: 10.1021/acsearthspacechem.9b00071). Measuring the porosity of rocks is important in petroleum engineering and for understanding geological carbon dioxide sequestration, groundwater flow, and the use of rocks as building materials. Na Li of the Chengdu University of Technology and colleagues used silane molecules to covalently attach a dye, rhodamine B, to silica-coated Fe3O4 magnetic nanoparticles. The team then used a strong magnetic field to pull the nanoparticles through rock samples about 30 µm thick. The samples showed stronger fluorescence than others that were loaded with nanoparticles that were physically coated with dye, without the silane linker. To measure the sizes of the pores and pore junctions, the team made nanoparticles ranging from 65 to 120 nm in size, each of which had different peak fluorescence wavelengths,