Electrochemical Sensor For Nonenzymatic Detection Research Articles

A Flexible and Transparent PtNP/SWCNT/PET Electrochemical Sensor for Nonenzymatic Detection of Hydrogen Peroxide Released from Living Cells with Real-Time Monitoring Capability.

We developed a transparent and flexible electrochemical sensor using a platform based on a network of single-walled carbon nanotubes (SWCNTs) for the non-enzymatic detection of hydrogen peroxide (H2O2) released from living cells. We decorated the SWCNT network on a poly(ethylene terephthalate) (PET) substrate with platinum nanoparticles (PtNPs) using a potentiodynamic method. The PtNP/SWCNT/PET sensor synergized the advantages of a flexible PET substrate, a conducting SWCNT network, and a catalytic PtNP and demonstrated good biocompatibility and flexibility, enabling cell adhesion. The PtNP/SWCNT/PET-based sensor demonstrated enhanced electrocatalytic activity towards H2O2, as well as excellent selectivity, stability, and reproducibility. The sensor exhibited a wide dynamic range of 500 nM to 1 M, with a low detection limit of 228 nM. Furthermore, the PtNP/SWCNT/PET sensor remained operationally stable, even after bending at various angles (15°, 30°, 60°, and 90°), with no noticeable loss of current signal. These outstanding characteristics enabled the PtNP/SWCNT/PET sensor to be practically applied for the direct culture of HeLa cells and the real-time monitoring of H2O2 release by the HeLa cells under drug stimulation.

MoS2 based ultra-low-cost, flexible, non-enzymatic and non-invasive electrochemical sensor for highly selective detection of Uric acid in human urine samples

While all reports on electrochemical uric acid (UA) sensors are on rigid electrodes and based on either complex fabrication procedures or multiple steps based synthesis techniques, this paper is the first demonstration of a single step hydrothermally grown MoS2 on aluminium foil (Al) based flexible electrochemical sensor for non-enzymatic detection of UA. FESEM images revealed MoS2 micro-flower like structure comprising of interlaced nanosheets while chemical characterization data confirmed the successful growth of few layered (>4 layers) MoS2 on Al foil. The as-fabricated flexible sensor exhibited a limit of detection of 1.169 μM, a response time of <3 s, excellent reproducibility, selectivity towards UA over glucose, ascorbic acid and urea with a sensitivity of 98.3 ± 1 nA μM−1 (R2 = 0.999) in the dynamic range of 10–400 μM. This enhanced sensing ability can be attributed to high surface area of MoS2, more numbers of active sites resulting from large numbers of defects and edges and higher proportion of metallic 1 T phase than semiconducting 2H phase. The proposed sensor was also successfully evaluated for the detection of UA in a non-invasive sample like human urine and the data corroborates well with the UA concentration obtained from conventional biochemical tests performed in clinical laboratory. This highly sensitive, ultra-low-cost MoS2 based flexible electrochemical sensor paves way for the development of affordable lab on chip devices for a wide range of bioanalytical applications.

Graphene–Polyaniline composite based ultra-sensitive electrochemical sensor for non-enzymatic detection of urea

Detection of urea is of prime importance in food and water safety, dairy industries and environmental monitoring. Traditional methods to detect urea are either expensive and involve sophisticated instrumentation or are based on enzymatic approach of detection. Herein, we report a Graphene-Polyaniline (Gr-PANi) based electrochemical sensor for non-enzymatic detection of urea. Gr-PANi composite was synthesized by electro-deposition of PANi on the surface of Gr modified GCE using cyclic voltammetry (CV) technique. The presence of Gr and PANi in the composite was confirmed using a multitude of characterization techniques which included FESEM, XRD and Raman spectroscopy. The electrochemical behavior of urea at the surface of Gr-PANi modified GCE was studied by CV whereas urea sensing was performed by using simple current-potential (I–V) technique. The current response of the as-fabricated urea sensor was∼4.74 folds greater than that of pure PANi based sensor and ∼67.2 times greater than that of pure Gr based sensor. The sensing performance of the composite based urea sensor was optimized by varying the thickness of PANi film. The optimized sensor exhibited lower limit of detection (5.88μM), excellent reproducibility, selectivity and stability with an enhanced sensitivity of −226.9μA/μM cm2 (R2=0.993) in the range of 10μM–200μM. The reliability of the as-fabricated sensor was successfully investigated by using it to detect urea concentrations in samples of tap water and milk samples. This highly-sensitive Gr–PANi composite based urea sensor provides a simple, low cost, non-enzymatic approach for detection of urea that find numerous applications in clinical diagnostics, dairy industries, fertilizer plants and environmental monitoring.

A nanocomposite-based electrochemical sensor for non-enzymatic detection of hydrogen peroxide.

Hydrogen peroxide (H2O2) plays important signaling roles in normal physiology and disease. However, analyzing the actions of H2O2 is often impeded by the difficulty in detecting this molecule. Herein, we report a novel nanocomposite-based electrochemical sensor for non-enzymatic detection of H2O2. Graphene oxide (GO) was selected as the dopant for the synthesis of polyaniline (PANI), leading to the successful fabrication of a water-soluble and stable GO-PANI composite. GO-PANI was subsequently subject to cyclic voltammetry to generate reduced GO-PANI (rGO-PANI), enhancing the conductivity of the material. Platinum nanoparticles (PtNPs) were then electrodeposited on the surface of the rGO-PANI-modified glassy carbon electrode (GCE) to form an electrochemical H2O2 sensor. Compared to previously reported sensors, the rGO-PANI-PtNP/GCE exhibited an expanded linear range, higher sensitivity, and lower detection limit in the quantification of H2O2. In addition, the sensor displayed outstanding reproducibility and selectivity in real-sample examination. Our study suggests that the rGO-PANI-PtNP/GCE may have broad utility in H2O2 detection under physiological and pathological conditions.