Construction of High-Efficiency Blue/Red Fluorescent Dual Anti-Counterfeiting Based on Reed-Based Carbon Dots/MCM-41...

The complex multi-layered security signals about fluorescence-based anti-counterfeiting technology with smartphone-based readers are getting a lot of attention. The blue/red biobased fluorescent carbon dots (CDs) with an average particle size of 2.73 nm are prepared using reed, O-Phenylenediamine (OPD) and Phosphoric acid (H₃PO₄) as precursors by a facile hydrothermal method without organic solvents. To prevent carbon dot aggregation and experience self-quenching in water or organic solvents, CDs are embedded into the high-performance porous silica material (MCM-41) by another hydrothermal treatment. In contrast, the silica framework of MCM-41 provides essential physical protection for the CDs, allowing for their uniform distribution within the material. This leads to improved fluorescence intensity, increased fluorescence lifetime of 2.02 ns, and a quantum yield of 33.29%. The matrices on filter paper, hydrogels (cellulose), and membranes (polyvinyl alcohol) with CDs@MCM-41 demonstrate distinct color variations under daylight, UV light, and a filter, this capability facilitates simple yet effective multi-layer security features for anti-counterfeiting applications, with accurate and fast color analysis can be achieved through the RGB software on a smartphone.