Isolated PEDOT-based organic-ionic-hydrogel as the sensitive portable electroanalytical platform for paracetamol determination

Abstract

The use of ionic liquids, protonic acids or organic reagents to remove PSS from PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)) to improve the conductivity is an efficient strategy [1]. Meanwhile, the merits of low cost/toxicity, easy operation and environmental friendliness of ethylene glycol (EG) make it the primary candidate for separating PEDOT:PSS [2]. Herein, the PEDOT:PSS was treated with EG to obtain partially isolated PEDOT, referred to as Pi-PP, then the Pi-PP was effectively integrated with Ca²⁺ and chitosan-acrylamide hydrogel to develop composite hydrogels (CS-AM(Ca²⁺)-EG@Pi-PP). Subsequently, an electrochemical sensor (CS-AM(Ca²⁺)-EG@Pi-PP/SPE) was developed using the prepared hydrogels in conjunction with a screen-printed electrode (SPE). Using paracetamol as the target analyte, this sensor demonstrated an ultra-sensitive linear detection range (0.01–5000 μmol/L) and a low detection limit of 0.003 μmol/L. The excellent electroanalytical performance may contribute to that i) EG facilitates the removal of some insulating PSS via shielding effects, exposing more conductive components (Pi-PP); ii) the intrinsic ionic conductivity of Ca²⁺ also enhances the current response of PARA, and iii) the dense network channels of hydrogel are conducive to the transmission of PARA. In short, the electrochemical origin is: PARA undergoes a redox reaction on the electrode surface to generate the current signal, and then this sensor detects the analyte via measuring the change of the current. This study presents valuable insights for creating an efficient, and portable electrochemical sensing platform for environment and human health.