FeS₂ Grown Pencil Graphite as an In‐expensive and Non‐enzymatic Sensor for Sensitive Detection of Uric Acid in Non‐invasive Samples

Abstract

While most electrochemical uric acid (UA) sensors are developed on the conventional electrodes and involve either multiple steps based synthesis routes and/or complicated fabrication processes, this paper is the first demonstration of direct growth of pyrite FeS2 on pencil‐graphite electrode (PGE) for non‐enzymatic UA sensing. FESEM images of the pyrite FeS2‐PGE reveal mesoporous microspherical structure of pyrite FeS2 along with graphite flakes of PGE and EDX, Raman spectroscopic data validate growing of pyrite FeS2 on PGE. The pyrite FeS2‐PGE sensor exhibited detection limit of 6.7 μM, excellent linearity, reproducibility, selectivity over glucose, urea, ascorbic acid with the sensitivity of 370 μA mM−1 cm−2 in the range of 10–725 μM of UA. These improved analytical performances can be attributed to high conductivity of the pyrite FeS2, larger electro‐active surface area of the mesoporous microspherical pyrite FeS2 grown on PGE (than only PGE) and abundance in defect sites originating from both the pyrite FeS2 as well as functional groups of pencil graphite. Furthermore, the sensor was validated against UA in urine sample and the result supports well with the UA concentration achieved from colorimetric technique. Development of this low cost, non‐enzymatic, sensitive and highly selective pyrite FeS2‐PGE bases UA sensor is a significant step in the development of practically viable sensors for point‐of‐care applications in clinical and pharmaceutical analyses.

Ultra-low cost, smart sensor based on pyrite FeS2 on cellulose paper for the determination of vital plant hormone methyl jasmonate

“…In the XRD pattern (figure 3(b)) of the pyrite FeS 2 grown on cellulose paper, the diffraction peaks at 2θ=28.67°, 33.2°, 37.25°, 40.96°, 47.62°, 56.37°, 59.3°, 61.69°, 64.37°and 79°are attributed to (111), ( 200), (210), ( 211), ( 220), (311), ( 222), ( 023), ( 321) and (420) hkl planes of pyrite FeS 2 respectively. All these peaks support well with the JCPDS card # 79-0617 and the previous reports [15,17]. Moreover, other peaks at 2θ=∼16°and 22°denote the presence of cellulose paper and also infer that the paper substrate was not degraded during the hydrothermal growth of pyrite FeS 2 on paper.…”

“…Three peaks in the 2θ range of ∼35°to 55°w ith very small intensity which are not assigned in the XRD spectrum are owing to unreacted S atoms. These unreacted S atoms induce defects thus providing more number of active sites during MeJa sensing [17]. Here, to achieve high sensitivity, differential pulse voltammetry (DPV) technique was used for the detection of MeJa.…”

Paper Based Low‐Cost and Portable Ultrasensitive Electroanalytical Devicefor The Detection of Uric Acid in Human Urine

“…Uric acid (UA) is an efficient biomarker that is formed during the end of purine metabolism in humans [24] . On an average, healthy individuals secrete 1.5–4.5 mM UA per day through urine [25] . Unusual changes in the amount of UA may lead to various diseases such as gout, obesity, high blood pressure, arthritis, and other kidney‐related diseases [24,25] .…”

“…On an average, healthy individuals secrete 1.5–4.5 mM UA per day through urine [25] . Unusual changes in the amount of UA may lead to various diseases such as gout, obesity, high blood pressure, arthritis, and other kidney‐related diseases [24,25] . Therefore, early diagnosis of UA levels is vital for ensuring continued human health.…”

“…Various analytical techniques, like capillary electrophoresis, colorimetry, high‐performance liquid chromatography, fluorescence spectroscopy, have been developed for the analysis of UA [26,27,28,29] . Among these various techniques, electrochemical based techniques overcome the issues of conventional techniques like the requirement of sophisticated instrumentation, operational complexity, and feasibility of on‐site monitoring [15,24,25,30] . Often, electroanalytical techniques like cyclic voltammetry (CV) and differential pulse voltammetry (DPV) are employed in electrochemical sensing approaches.…”