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Abstract Gold nanodendrite (AuND) is a type of gold nanoparticles with dendritic or branching structures that offers advantages such as large surface area and high conductivity to improve electrocatalytic performance of electrochemical sensors. AuND structures can be synthesized using electrodeposition method utilizing cysteine as growth directing agent. This method can simultaneously synthesize and integrate the gold nanostructures on the surface of the electrode. We conducted a comprehensive study on the synthesis of AuND on screen-printed carbon electrode (SPCE)-based working electrode, focusing on the optimization of electrodeposition parameters, such as applied potential, precursor solution concentration, and deposition time. The measured surface oxide reduction peak current and electrochemical surface area from cyclic voltammogram were used as the optimization indicators. We confirmed the growth of dendritic gold nanostructures across the carbon electrode surface based on FESEM, EDS, and XRD characterizations. We applied the SPCE/AuND electrode as a nonenzymatic sensor on ascorbic acid (AA) and obtained detection limit of 16.8 μM, quantification limit of 51.0 μM, sensitivity of 0.0629 μA μM−1, and linear range of 180–2700 μM (R2 value = 0.9909). Selectivity test of this electrode against several interferences, such as uric acid, dopamine, glucose, and urea, also shows good response in AA detection.

AbstractIntegration of gold nanoparticles onto electrochemical biosensor electrodes has been widely conducted to improve the performance of biosensors. Gold nanospikes (AuNS), as one of the gold nanoparticle morphologies, can be integrated into biosensors through electrodeposition and has the potential to immobilize bioreceptor on biosensors using the self-assembled monolayer (SAM) method. This paper examines the potential of AuNS-deposited Screen-Printed Carbon Electrodes (SPCEs) on immobilizing enzymes as label-based electrochemical biosensor by evaluating the optimum parameter for glucose oxidase (GOx) enzyme immobilization on the SPCE that consists of incubation time and concentration of SAM molecule—L-cysteine—and GOx enzyme, then reviews its performances. The developed biosensor exhibits excellent performance in detecting glucose (linear range of 0.2–15 mM and limit of detection (LOD) of 116 µM), with good selectivity against uric acid, urea, ascorbic acid, dopamine, and lactic acid, and superiority towards gold nanosphere modified biosensor.

Electrochemical measurement methods are widely used to analyze various biochemical reactions due to their simplicity and versatility. Therefore, the development of potentiostats, electrochemical-based analytical instruments, that are low in cost but maintaining rich analytical features is highly demanding. In this paper, we report the development of a low-cost and portable potentiostat system, named ESPotensio, which supports six different electrochemical measurement methods and a multi-channel electrochemical measurement. The measurement methods it supports include the cyclic voltammetry (CV), linear sweep voltammetry (LSV), square wave voltammetry (SWV), differential pulse voltammetry (DPV), normal pulse voltammetry (NPV), and the observation of electrochemical response current against time based on chronoamperometry (CA) measurement method. Moreover, each of these measurement methods can be run semi-parallelly within three different channels. The electrochemical measurement precision, accuracy, and error of ESPotensio were evaluated based on the repeated measurements and the comparison with the commercial potentiostats. The results showed that it could produce highly accurate electrochemical measurements by having an average accuracy of more than 90% compared to the commercial potentiostat, Emstat Pico. Ultimately, the hardware design was determined accordingly to meet the low-cost demand by costing of only USD 21.4 for the total system realization.

The electrochemical-based analysis provides simplicity, robustness, and relatively less maintenance. Specifically, a low-cost potentiostat, a basic equipment to conduct electrochemistry experiments and analysis, is necessary to aid small-medium educational units to develop a multifunctional mini-laboratory, particularly for education. In addition, the development of portable and small instruments could be essential to obtain a wider technology adopters implication. In this paper, eSTAT, a low-cost and smartphone controlled potentiostat system was developed based on ESP32 microcontroller. The performance of eSTAT was evaluated from the Cyclic Voltammetry (CV) measurements, from which the accuracy and the error tolerance of the system were determined. The results showed that the eSTAT could measure the Voltammogram signal with the accuracy of 98.30% for the anodic peak current and 87.84% for the cathodic peak current relative to the commercial Zimmer&Peacock ANA POT EIS potentiostat. In addition, the wireless control of eSTAT could be done wirelessly via Bluetooth using an external application made on Android OS.

In this study, we reported the construction of Gold Nanospike (AuNS) structures on the surface of screen-printed carbon electrode (SPCE) used for non-enzymatic electrochemical detection. This modification was prepared with a one-step electrodeposition method by controlling the electrodeposition parameters, such as applied potential and deposition time, via Constant Potential Amperometry (CPA). Those parameters and precursor solution concentration were varied to investigate the optimum electrodeposition configuration. The results confirmed that AuNS were homogenously deposited and well-dispersed on the working electrode surface of SPCE. The AuNS-modified SPCE was implemented as a non-enzymatic sensor toward dopamine and could enhance the electrocatalytic ability compared with the bare SPCE. Further examination shows that the sensing performance of the AuNS-modified SPCE produced an increase in electrochemical surface area (ECSA) at 17.25 times higher than the bare electrode, a sensitivity of 0.056 µA mM−1 cm−2 with a wide linear range of 0.2–50 µM and a detection limit of 0.33 µM. In addition, AuNS-modified SPCE can selectively detect dopamine among other interfering analytes such as ascorbic acid, urea, and uric acid, which commonly coexist in the body fluid. This work demonstrated that AuNS-modified SPCE is a prospective sensing platform for non-enzymatic dopamine detection.