Efficient loading of curcumin into CTAB micelle-embedded silica particles for visualized pH detection

Incorporation of curcumin (Cur) into silica (SiO2) matrix has been considered to be an effective way to improve its dispersing ability, stability and performance in aqueous media. In this work, we demonstrate a facile approach for highly efficient encapsulation (≥ 99%) of Cur into SiO2 particles embedded with cetyltrimethylammonium bromide (CTAB) micelles. Emission properties of Cur loaded are well dependent on the packing fashion of CTAB micelles embedded in the SiO2 particles. Cur loaded in the CTAB micelles quasi-crystalline in structure was sensitive to the variation in pH of the surrounding media, attributed to gradual deprotonation of Cur with the elevated pH. In comparison, Cur loaded in the CTAB micelles amorphous in character was less sensitive to the change of pH due to the direct electrostatic interaction between Cur and CTAB. Further incorporation of a green emissive dye, i.e., into the Cur doped silica particles allows the fabrication of multicolor SiO2 particles qualified for visualized detection of pH.