Layer-by-layer assembly of composite conductive fiber-based organic electrochemical transistor for highly sensitive detection of sialic acid

A novel composites conductive fiber based on Poly(diallyldimethylammonium chloride) and multi-walled carbon nanotubes/Poly(3, 4-ethylenedioxythiophene)-Poly(styrenesulfonate) has been prepared using layer-by-layer assembly (LBL) technology. The characterization results showed the composites film was successful prepared on the cotton fiber and had flexibility, conductivity and washability. The fiber-based organic electrochemical transistors (FECTs) have been assembled by the LBL composite fiber, which exhibit an on/off ratio of 5.12*102±17.99, a peak transconductance value of 8.7 mS, a switching response time of 1.2 s, and excellent cycle stability. Bending and repetitive hand-washing cycles of fibers have no significant influence on the electrical properties of FECTs. Moreover, FECTs maintain stable electrical properties within a week. The gate electrode of the FECT was modified with 3-aminophenylboronic acid to prepare a sialic acid (SA) biosensor. The SA biosensor based on FECTs presented a sensitivity of 57.66 mV per decade, a good linear response in a wide concentration range of 1 nM-1 mM, a linear coefficient R2=0.9848. This biosensor can be successful used to detect the SA content in saliva. Most importantly, the sensor can be integrated into fabrics with no significantly change in the device performance before and after weaving, providing an efficient detection platform for wearable healthcare application.