Ultrasensitive detection of trypsin in serum via nanochannel device.

A highly sensitive trypsin sensing system in serum was developed by using an anodic alumina oxide (AAO)-based, trypsin substrate-decorated hybrid ion permeation membrane. Owing to the trypsin-triggered peptide hydrolyzation reaction, the surface electrical feature of the peptide-decorated hybrid ion membrane changed. The electric double layer effect reduces the effective ion current diameter in the AAO nano unit, so that the ion current rectification ratio will be enhanced, realizing the quantitative detection of trypsin. The lowest detection concentration can be achieved as low as 0.1 pM. This method is no need for sample pre-preparation, easy to operate, highly sensitive, and also applicable to other enzyme evaluation systems by changing corresponding substrates. This study provides a new idea for selective measurements of proteases in complex biological samples.