Abstract
Herein, we have designed and demonstrated a facile and effective platform for the covalent anchoring of a tetrameric hemoprotein, hemoglobin (Hb). The platform comprises of naphthyl substituted amine functionalized gel type hydrophobic ionic liquid (NpNH2-IL) through which the heme protein was covalently attached over a glassy carbon electrode (Hb-NpNH2-IL/GCE). UV-vis and FT-IR spectral results confirmed that the Hb on NpNH2-IL retains its native structure, even after being covalently immobilized on NpNH2-IL platform. The direct electron transfer of redox protein could be realized at Hb-NpNH2-IL/GCE modified electrode and a well resolved redox peak with a formal potential of −0.30 V and peak separation of 65 mV was observed. This is due to the covalent attachment of highly conducting NpNH2-IL to the Hb, which facilitates rapid shuttling of electrons between the redox site of protein and the electrode. Further, the fabricated biosensor favoured the electrochemical reduction of bromate in neutral pH with linearity ranging from 12 to 228 µM and 0.228 to 4.42 mM with a detection limit and sensitivities of 3 µM, 430.7 µA mM−1 cm−2 and 148.4 µA mM−1 cm−2 respectively. Notably, the fabricated biosensor showed good operational stability under static and dynamic conditions with high selectivity and reproducibility.
Highlights
Ionic liquids (ILs) are superior class of non-molecular ionic materials that possesses multifaceted customizable properties
We have demonstrated the covalent immobilization of Hb on our newly synthesized amine functionalized gel type hydrophobic ionic liquid through terephthaloyl chloride cross-coupling reaction
The synthesis of naphthyl substituted amine functionalized IL was monitored using 1H, 13C & 19F NMR and HRMS spectral analysis (Supplementary Figures S1–S8) and the spectral data were in accordance with the synthesized compounds
Summary
Ionic liquids (ILs) are superior class of non-molecular ionic materials that possesses multifaceted customizable properties They are fascinating melts of salts, composed of asymmetric or bulky organic cation with organic or inorganic anions that can undergo varieties of structural and functional variations[1,2,3]. Covalent immobilization of biomolecules on ILs containing suitable reactive functional groups would enhance the electrical contact as well as improve the operational stability[23,24]. Design and synthesis of novel ILs with suitable functional group becomes imperative for specific applications, whereas reports on functionalized ILs are very scarce This motivated us to design various functionalized IL based platforms for covalent immobilization of biomolecules[23]. The biosensor displayed remarkable performance towards the detection of bromate, which is attributed to the simple and effective architect offered by the NpNH2-IL platform
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