Application of hydrogels based on carbon dots and rare earths in dual-wavelength UV excitation adjustable multicolor fluorescence

Abstract

This study presents a multifunctional hydrogel engineered by integrating carbon dots (CDots) and lanthanide metal ions (Ln³⁺), which exhibits tunable multicolor fluorescence under dual-wavelength UV excitation (254 nm and 365 nm). Systematic characterization via scanning electron microscopy (SEM), mechanical analysis, and fluorescence spectroscopy revealed three key features: distinct chromatic transitions between excitation wavelengths, favorable mechanical robustness, and long-term stability. The programmable fluorescence behavior, achieved through precise Ln³⁺ stoichiometric control and CDot-mediated energy transfer mechanisms, enables optical encryption with dual-excitation modes. Furthermore, the hydrogel demonstrates visual ion detection capabilities, exhibiting rapid fluorescence responses toward Zn²⁺ and K⁺via specific coordination interactions. This dual-functional hydrogel advances the development of intelligent materials for anti-counterfeiting technologies and environmental monitoring applications.