Ionic liquid-hydrogel hybrid material for enhanced electron transfer and sensitivity towards electrochemical detection of methamphetamine

Abstract

Reliable onsite biosensors for detecting drugs of abuse are of critical importance for the current society. Electrochemical sensors, especially screen-printed electrode (SPE)-based sensors, are a strong candidate for onsite drug detection. Although many SPE-based sensors are being developed, enhancing these tools’ sensitivity and analytical capacity is a continuous endeavor. Here, we propose a novel approach for SPE surface modification using a combination of hydrogel, ionic liquid, and specific antibodies to detect methamphetamine in human saliva samples. The hydrogel-ionic liquid (ionogel) was synthesized from gelatin, PEG, and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. FTIR and SEM were used to characterize the material before it was applied over a screen-printed gold electrode for electrochemical measurements using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). After optimization, the calibration of the proposed sensor showed a detection range between 5.0 and 1000 ng/mL with a LOD = 0.56 ng/mL in PBS. Application of the sensor with spiked human saliva demonstrated enhanced sensitivity with a LOD = 0.72 ng/mL. The repeatability and reproducibility of the proposed biosensor demonstrated a coefficient of variance (CV%) reaching 6.92% and 2.53%, respectively. The biosensor showed a high specificity toward methamphetamine compared to other interferents. The current ionogel-based electrochemical immunosensor offers a promising and versatile tool for sensitive onsite detection of substance abuse.