Nanoengineered β-MnO2/rGO nanobead-based bioconjugate interfaces for the electrochemical detection of dopamine for the potential to manage neurological diseases and depression

Abstract

In this study, we successfully developed a highly effective nanobead (nb) morphology-based β-MnO₂/rGO nanocomposite via low-temperature hydrothermal synthesis. These nb morphologies possess significant surface areas, enabling the efficient loading of biomolecules and facilitating excellent charge transfer from substrates to analytes. The resulting nanocomposite was used as a dopamine (DA) biosensor, a crucial monoamine neurotransmitter in living organisms. The instability of DA concentration in biological fluids contributes to various diseases, including Parkinson's disease, hyperactivity disorder, Alzheimer's disease, and dementia. To address these challenges, ex situ hydrothermally prepared nb-β-MnO₂/rGO nanocomposite conjugates with tyrosinase (Tyr) enzyme were used to fabricate amperometric DA biosensor interfaces. Various characterization techniques, such as XRD, FTIR spectroscopy, Raman spectroscopy, AFM, SEM, and TEM, were used to analyze the structural and morphological features of the fabricated nanocomposite. The Tyr/nb-β-MnO₂/rGO/ITO bioelectrode exhibited efficient electrocatalytic activity towards the oxidation of DA, outperforming the rGO and nb-β-MnO₂-fabricated electrode due to the synergistic effect of the nb-β-MnO₂/rGO nanocomposite. The Tyr/nb-β-MnO₂/rGO/ITO biosensor demonstrated excellent analytical performance with a longer linear range (1–250 μM), high sensitivity (2.633 × 10⁻⁶ A μM⁻¹ cm⁻²), low detection limit (6.42 × 10⁻² μM), fast response time (10 s), extended stability (80 days), and high reproducibility (13 number of scans). This promising nanobead morphology-based β-MnO₂/rGO electrode is used for various amperometric biosensing applications.