Abstract
Transition metals have been explored extensively for non-enzymatic electrochemical detection of glucose. However, to enable glucose oxidation, the majority of reports require highly alkaline electrolytes which can be damaging to the sensors and hazardous to handle. In this work, we developed a non-enzymatic sensor for detection of glucose in near-neutral solution based on copper-nickel electrodes which are electrochemically modified in phosphate-buffered saline (PBS). Nickel and copper were deposited using chronopotentiometry, followed by a two-step annealing process in air (Step 1: at room temperature and Step 2: at 150 °C) and electrochemical stabilization in PBS. Morphology and chemical composition of the electrodes were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cyclic voltammetry was used to measure oxidation reaction of glucose in sodium sulfate (100 mM, pH 6.4). The PBS-Cu-Ni working electrodes enabled detection of glucose with a limit of detection (LOD) of 4.2 nM, a dynamic response from 5 nM to 20 mM, and sensitivity of 5.47 0.45 at an applied potential of 0.2 V. In addition to the ultralow LOD, the sensors are selective toward glucose in the presence of physiologically relevant concentrations of ascorbic acid and uric acid spiked in artificial saliva. The optimized PBS-Cu-Ni electrodes demonstrate better stability after seven days storage in ambient compared to the Cu-Ni electrodes without PBS treatment.
Highlights
Diabetes is a worldwide health problem and one of the leading causes of death and disability [1,2]
We investigated various annealing conditions and showed that the initial
This work demonstrates the synthesis and application of phosphate-buffered saline (PBS)-treated Cu-Ni electrodes as the working electrode for non-enzymatic electrochemical sensing of glucose in nearneutral solution, which is a distinct advantage compared to other non-noble metal glucose catalysts
Summary
Diabetes is a worldwide health problem and one of the leading causes of death and disability [1,2]. Patients with diabetes are clinically advised to monitor their glucose levels regularly [2,3]. Treatment for diabetes requires accurate glucose monitoring, which has made developing glucose sensors a highly active research area in the biosensor community, especially in the point-of-care testing domain. Conventional electrochemical glucose sensors use the glucose oxidase (GOx) enzyme which offers superior selectivity and good sensitivity for detecting glucose in physiological pH. Enzymes suffer from stability issues due to their sensitivity to changes of pH, temperature, humidity, and interference of some electro-oxidizable species [4–10]. Enzymatic sensors are limited by enzyme leaching, electrode replacement [11], and are not amenable for electrode miniaturization [12]
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