A Near-Infrared Light Triggered Fluormetric Biosensor For Sensitive Detection Of Acetylcholinesterase Activity Based On Naerf4: 0.5 % Ho3+@Nayf4 Upconversion Nano-Probe

Acetylcholinesterase (AChE), as an important neurotransmitter, is widely present in the peripheral and central nervous systems. The aberrant expression of AChE could cause diverse neurodegenerative diseases. Herein, we developed a facile and interference-free fluorimetric biosensing platform for highly sensitive AChE activity determination based on a NaErF4: 0.5 % Ho3+@NaYF4 nano-probe. This nano-probe exhibits a unique property of emitting bright monochromic red (650 nm) upconversion (UC) emission under multiband (-808, -980, and -1530 nm) near-infrared (NIR) excitations. The principle of this detection relies on the quenching of the strong monochromic red UC emission by oxidization products of 3,3 ',5,5 '-tetramethylbenzidine generated through AChE-modulated cascade reactions. This system shows a great sensing performance with a detection limit (LOD) of 0.0019 mU mL 1 for AChE, as well as good specificity and stability. Furthermore, we validated the potential of the nano-probe in biological samples by determination of AChE in whole blood with a LOD of 0.0027 mU mL-1, indicating the potential application of our proposed platform for monitoring the progression of AChE-related disease.