The accurate detection of vital biomarkers such as Ascorbic Acid (AA), Uric Acid (UA) and Nitrite ( NO2 −) is crucial for human health surveillance. However, existing methods often struggle with concurrent detection and quantification of multiple species, highlighting the need for a more effective solution. To address this challenge, this study aimed to develop a multifunctional electrochemical sensor capable of parallel detection of AA, UA and NO2 − using a synergistic combination of Graphene Oxide (GO) and Cadmium Sulfide (CdS) materials. Notably, the fabricated CdS@GO/Glassy Carbon Electrode (GCE) exhibited exceptional electrochemical activity, as evidenced by Differential Pulse Voltammetry (DPV) analysis. The sensor demonstrated remarkable sensitivity (8.13, 10.12, and 9.05 μA·μM−1·cm−2) and ultra-low detection limits (0.034, 0.062, and 0.084 μM) for AA, UA and NO2 −, respectively. Furthermore, it successfully identified single molecules of each analyte in aqueous and biologic fluid samples, with recovery values comparable to those obtained using High-Performance Liquid Chromatography (HPLC) standard addition methods. The significance of this study lies in developing a novel CdS@ GO/GCE sensor that enables concurrent detection and quantification of multiple vital biomarkers, offering a promising tool for human health monitoring and diagnosis.

Facile fabrication of CdS@GO binary nanocomposite coated GCE for separate and parallel electrochemical sensing of ascorbic acid, uric acid and nitrite
    Abstract
    1 Introduction
    2 Materials and method
        2.1 Reagents and chemicals
        2.2 Instrumentation details
        2.3 Synthesis of CdS@GO nanocomposite
        2.4 Preparation of CdS@GO electrode
        2.5 Measurement of AA, UA and NO- 2 in a serum sample
    3 Results and discussion
        3.1 Characterization results
        3.2 Electrochemical kinetic study of CdS@GOGCE
        3.3 Electrochemical behavior of AA
        3.4 Influence of scan rate AA oxidation
        3.5 Effect of pH
        3.6 Voltammetric determination of AA
        3.7 Separate and simultaneous detection of AA, UA and NO2−
        3.8 Cyclic stability and reproducibility of the CdS@GOGCE
        3.9 Interference studies
        3.10 Real sample analyses
    4 Conclusion
    References

• Huan Pang(School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225127, People’s Republic of China)
• A. Dhamodharan(School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225127, People’s Republic of China, School of Food Science and Technology, Yangzhou University, Yangzhou, Jiangsu 225127, People’s Republic of China)
• Yajun Gao(School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225127, People’s Republic of China, School of Food Science and Technology, Yangzhou University, Yangzhou, Jiangsu 225127, People’s Republic of China)
• E. Murugan(Department of Physical Chemistry, School of Chemical Sciences, University of Madras, Guindy Campus, Chennai, Tamilnadu 600025, India)
• K. Perumal(Department of Physics, Science and Humanities, Jeppiaar Engineering College, Chennai 600119, India)
• K. Jhansirani(Department of Materials Science and Engineering, National Dong Hwa University, Shoufeng, Hualien 97401, Taiwan)