Colorimetric sensing for the sensitive detection of UO22+via the phosphorylation functionalized mesoporous silica-based controlled release system

Abstract

In this study, we developed a simple and sensitive colorimetric sensing method for the detection of UO₂²⁺, which was built to release MB from the molybdenum disulfide with a phosphate group (MoS₂-PO₄) gated mesoporous silica nanoparticles functionalized phosphate group (MSN-PO₄) with UO₂²⁺ chelating. In the presence of UO₂²⁺, MoS₂-PO₄ can be effectively adsorbed onto the surface of MSN-PO₄ based on the coordination chemistry for strong affinity between the P–O bond and UO₂²⁺. The adsorbed MoS₂-PO₄ was then utilized as an ideal gate material to control the release of signal molecules (MB) entrapped within the pores of MSN-PO₄, resulting in a detectable decrease in the absorption peak at 663 nm. This colorimetric sensing demonstrated the advantages of simplicity and easy manipulation and exhibited a linear response to the concentration of UO₂²⁺ within the range of 0.02–0.2 μM. The detection limit of UO₂²⁺ was determined to be 0.85 nM, which was lower than the limit (130 nmol L⁻¹) set by the US Environmental Protection Agency. Furthermore, the proposed colorimetric sensing method has been utilized to determine UO₂²⁺ in samples of Xiangjiang River and tap water, and a high recovery rate was achieved. This method shows promising potential in preventing and controlling environmental pollution.