Amino-Functionalized Ti3C2 MXene Quantum Dots as Photoluminescent Sensors for Diagnosing Histidine in Human Serum

As an emerging zero-dimensional nanomaterial, MXene quantum dots (MQDs) have aroused the interest of researchers because of their unique physical and chemical characteristics. Here, a straightforward hydrothermal strategy was used to successfully produce the amino-functionalized Ti3C2 MQDs. The functionalized Ti3C2 MQDs exhibited bright blue fluorescence (FL), which was derived from its size effect and surface defects. In addition, Ni2+ can bind to the amino groups on the surface of Ti3C2 MQDs. The absorption of the excitation light by the light-absorbing substance causes nickel ions to effectively quench the photoluminescence of Ti3C2 MQDs, which can be explained by the internal filter effect (IFE). At the same time, the strong affinity of histidine (His) for Ni2+, which is absorbed by His to form a stable complex, causes Ni2+ to dissociate from the Ti3C2 MQD surface and restore the FL. Thus, a fluorescent sensor for detecting the His content in serum was developed. Overall, this work provides a method for the detection of His and shows that the Ti3C2 MQDs have great potential in biomedical and biosensing applications.