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 NaErF 4 : 0.5 % Ho 3+ @NaYF 4 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. • A NIR light triggered fluormetric biosensor for sensitive detection of AChE activity. • A NaErF 4 :0.5%Ho@NaYF 4 fluorescent probe with red upconversion emission under multi-band excitation in the NIR region. • Ho 3+ ions confine the excitation energy and minimize he energy loss. • The biosensor exhibits the detection limit of AChE as low as 0.0019 mU mL −1 .