An Electrochemical Sensor Based on a Facile Synthesis of Chitosan-Blend-Polyaniline Decorated COOH-MWCNT-Hollandite/ α -MnO₂ Nanocomposites for Creatinine Detection

This paper comprehensively reports novel synthesis of bio-compatible and sustainable nano-composite based electrochemical sensor comprising of natural and conducting polymers; chitosan (CHIT) and polyaniline (PANI), carboxylic acid functionalized multiwalled carbon-nanotubes (COOH-MWCNTs) and transition metal oxide; Hollandite (α-MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>), an allotrope of manganese dioxide for creatinine (CRE) detection. A facile chemical solution methodology is utilized for the synthesis process. The work emphasizes on a novel anatomical approach that promises excellent CRE affinity. α-MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is ingeniously encapsulated within the nano-tubes of COOH-MWCNT (α-MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>@COOH-MWCNT) and thereafter, blended polymers (CHIT-b-PANI) are decorated over α-MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>@COOH-MWCNT conjugate. The final composite obtained is CHIT-b-PANI/α-MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>@COOH-MWCNT. Drop coating technique is implemented to deposit CHIT-b-PANI/MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>@COOH-MWCNT on ITO laminated glass plate. Powder X-Ray Diffraction (P-XRD), High Resolution Transmission Electron Microscopy (HR-TEM), Field Emission Transmission Electron Microscopy (FETEM), Field Emission Scanning Electron Microscopy (FESEM), Scanning Electron Microscopy (SEM), Atomic Field Microscopy (AFM), Fourier Transform Infrared Spectroscopy (F-TIR) and UV-Visible Spectroscopy confirmed the successful anatomical morphology and chemical conformation of CHIT-b-PANI/α-MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>@COOH-MWCNT. The electro-catalytic affinity of CHIT-b-PANI/α-MnO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>@COOH-MWCNT/ITO towards CRE is investigated in a three electrode arrangement with a buffer solution (0.1M, pH 8) containing commercial CRE in different concentrations (1-334.46 μM). The developed CRE electrochemical sensor displayed excellent CRE-compatibility results exhibiting wider detection range, 1-243.48 μM (Regression coefficient, R<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> = 0.9601), inflated sensitivity of 3204.02 μAmM<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup>, low LOD and LOQ of 1.02 μM and 3.12 μM. Superior temperature stability (30-60°C), excellent anti-interference characteristics (COV 3.75%); exorbitant reproducibility (COV 0.75%), highly acceptable repeatability (COV 1.32%) and broader storage stability of 8 months (COV 5.34%) assured optimum sustainability of the developed sensor.