Modifying metal ion ratios in nickel-aluminum layered double hydroxide/reduced graphene oxide composites for selective electrochemical detection of antibiotics

Antimicrobial resistance (AMR) is a global threat that occurs as microorganisms evolve to resist antibiotic (ATB) overuse. To monitor this overuse, inexpensive, affordable, and adaptable sensors are required. While electrochemical sensors are promising, they cannot often distinguish between overlapping electrochemical interactions from multiple ATBs, resulting in poor analyte selectivity. To overcome this challenge, we design electrocatalysts consisting of nickel aluminum layered double hydroxides (NiAl-LDH) and their composites by altering the metal ion ratio to adjust the surface properties and selectivity of sensors. Synthesis of LDH and its graphene oxide (GO) composites is conducted using a low-temperature hydrothermal method. The prepared materials are characterized using various morphological and structural characterization techniques. Electrochemical characterization confirms that tuning the metal ion ratio allows sensors to differentiate between electrochemical reactions, improving the selective detection of amoxicillin and tetracycline from their mixtures. Addition of graphene oxide also enhances sensing capabilities. The optimized sensor has sensitivities of 137.6 nA µM−1 cm−2 and 161.4 nA µM−1 cm−2, and lower detection limits of 4.3 nM and 3.6 nM, respectively, for amoxicillin (Amx) and tetracycline (TC). Interferents have no significant effect on the detection of relatively low concentrations (10 µM) of the two ATBs. The electrodes can also detect the two analytes in tap water samples. This sensor methodology can potentially improve environmental antibiotic detection to mitigate the risk of antimicrobial resistance.