Trypan Blue-Based Carbon Dots for Sensing of Al³⁺ in Real Samples and Living Cells

Aluminum is widely used in diverse fields of our daily life including maquillage, vaccine adjuvants, food packing, etc. Long-term aluminum exposure will lead to osteoporosis, Alzheimer's disease, and chronic renal failure. There still remains a need to develop low-cost, suitable, and rapid methods for the detection of Al³⁺. Herein, trypan blue-carbon dots (TB-CDs) were fabricated via a facile hydrothermal approach. The obtained TB-CDs were thoroughly analyzed by TEM, X-ray diffraction, FT-IR, XPS, UV-vis spectrophotometry, and fluorescence spectrophotometry. TB-CDs were spherical with a mean particle size of 2.9 nm and exhibited a high aqueous solubility with a fluorescence quantum yield of 6.37%. The obtained TB-CDs showed excellent photostability and relatively low cytotoxicity. The extent of fluorescence enhancement of TB-CDs was linearly related to the logarithmic concentration of Al³⁺. Thus, a fluorescence-on method was developed for fast and highly specific detection of Al³⁺ within the range of 0.5 to 4 μmol L^-1. The limit of detection was 0.2 μmol L^-1. Furthermore, the established sensing platform was successfully utilized for Al³⁺ determination in real samples and the intracellular imaging of Al³⁺. Owing to their convenience, low cost, and fast response, TB-CDs displayed promising potential in biochemical analysis and bioimaging fields.