Conducting polymers, with unique ion/electron transfer capability, reversible doping/dedoping and controllable chemical and electrochemical properties, have received many attention as advanced interfaces in electronic and bioelectronic devices. Recent advancement is focus on fine-tailoring the conducting polymer interfaces with addition functionality and controlled morphology with enhanced performance beyond its intrinsic properties.

Here, we demonstrate the tailoring of physico-chemical properties of poly (3,4-ethylenedioxythiophene) (PEDOT) with high density carboxyl functionality and tailored nano-structure, and its application in dopamine sensing and lactate biosensing with enhanced selectivity and sensitivity.

For dopamine sensing, we developed a high-density negatively-charged carboxyl functionalized PEDOT interface using a low-cost organic acid citrate as dopant. Citrate contains a high content of carboxyl functionality and small size allowing well distribution of the citrate dopant within the PEDOT with a high surface carboxyl density upto 26 µM/cm2. The carboxyl confined PEDOT interface with nano-globular structure showed increased electrode kinetics and increased discriminationof dopamine from interferences (ascorbic acid and uric acid).

For lactate biosensing, we further developed a nano-fibrillar carboxyl PEDOT interface that can detect dihydronicotinamide adenine dinucleotide (NADH) at low potential at ~0.43 V. Based on the post-immobilisation of NAD-dependent lactate dehydrogenase via carboxyl coupling, lactate biosensor was developed with good analytical performance and low operation potential to reduce interferences.

These results demonstrated tailoring of physico-chemical properties of PEDOT interface with improved sensing performance, thus could potentially applied for next generation bioelectronic devices such as wearable and flexible sensors and biosensors.