The Signal Amplification in Electrochemical Detection of Chloramphenicol Using Sulfonated Polyaniline‐chitosan Composite as Redox Capacitor

Abstract

In this work, a novel redox capacitor was designed for signal amplification in electrochemical detection. It was fabricated by co‐electrodeposition of a conducting polymer, sulfonated polyaniline (SPAN) and chitosan on a glass carbon electrode, and its function was evaluated for being a localized source to transfer electron between FcCOOH (Fc) and Ru(NH3)6Cl3 in solution via redox cycling. Furthermore, the electrochemical detection of chloramphenicol, a broad‐spectrum antibiotic was performed using the redox capacitor in the presence of Fc. A significant amplification in cathodic current response of chloramphenicol was obtained through a continuous redox‐cycling reaction. The performance of the amplifying signal responded linearly to chloramphenicol in a concentration range of 0.05 to 50.0 μmol L−1 with a low detection limit of 0.01 μmol L−1. The proposed approach exhibited good reproducibility and stability, and could be used for detection of chloramphenicol in eye drops by standard addition method with the recoveries from 96.5 % to 103.0 %.

Amplified Electrochemical Response of Phenol by Oxygenation of Tyrosinase Coupling with Electrochemical‐chemical‐chemical Redox Cycle

“…This result demonstrated that SPANÀ CS composite could be sequentially charged and discharged steady in each cycle when Ru(II/III) and catechol/o-benzoquinone were presented. This experimental result was consistent with our previous work [40] and the Payne group's work [44,45]. It also ensured the stability of amplified signal required in this experiment.…”

“…The synthetic experiment followed the previous work [40]: Aniline of 0.09 g and 3-Aminobenzenesulfonic acid of 0.24 g were added in 20.0 mL 0.15 mol L À 1 HCl, then the initiator of 10.0 mL 0.06 mol L À 1 ammonium persulfate was placed into the above solution. The whole copolymerization reaction was continuously carried out for 24 hours at 5°C under static conditions.…”

“…In our previous study, the SPANÀ CS composite (SPAN, E 0 = + 0.08 V, vs. Ag/AgCl) on electrode was acted as a localized source that could not directly transfer electrons to the underlying electrode, but could accept, store and donate electron between FcCOOH (Fc) (E 0 = + 0.30 V, vs. Ag/AgCl) and Ru(NH 3 ) 6 Cl 3 (E 0 = À 0.20 V, vs. Ag/AgCl) [40]. As shown in Figure S3, the CVs were utilized to investigate the electron transfer between TyrÀ SPANÀ CS/GCE and Ru(NH 3 ) 6 Cl 2 in PBS.…”

“…Then, the plot of the anodic current responses of catechol versus different pH value of PBS from 6.5 to 8.5 was obtained in Figure 4. The result indicated that there was a decrease in activity of the Tyr and redox activity of SPAN in alkaline condition, although electro-oxidation of catechol was fast in alkaline condition [40,46]. Hence, the PBS of pH 6.9 was selected as electrolyte solution in this work.…”

“…In our group, dopamine cross-linked CS films being redox capacitor as well as an indicator, has been developed for enhanced electrochemical sensing of saccharide [39]. In further study, a novel redox capacitor, sulfonated polyanilineÀ chitosan (SPANÀ CS) composite has been designed to exchange electrons between soluble redox species via redox cycling, and used in amplification of electrochemical signal of chloramphenicol [40].…”