A versatile logic-gated fluorescence turn-on nitrogen-doped carbon dots: STM32 microcontroller intelligent platform for assay of L-Histidine and Al(3).

Rapid and intelligent detection of bioactive molecules and metal ions is vital for health and environmental safety. Herein, a dual-functional nitrogen-doped carbon dots (N-CDs) for L-Histidine (L-His) and Al detection was developed employing chitosan (CTS) and umbelliferone (UMB) as the substrates. The N-CDs exhibited a distinct "turn-on" fluorescence response to L-His and a subsequent signal recovery towards Al with low detection limits (LODs) of 0.950 μM and 4.393 μM. The underlying sensing mechanisms were rigorously elucidated via density functional theory (DFT) calculations and independent gradient model based on Hirshfeld partition (IGMH) analyses, highlighting the pivotal role of surface functional groups. The practical applicants of N-CDs were demonstrated through the fabrication of fluorescent hydrogels, solid-state films for light-emitting diodes (LEDs), and anti-counterfeiting patterns. Notably, a portable and intelligent sensing platform driven by STM32 microcontroller was engineered to capture and analyze RGB signals to realize smart and on-site quantification of L-His, which provided a robust and cost-effective strategy for real-time monitoring of analytes in complex matrices.