Synthesis and Characterisation of Nanomolecular Conjugated Polymer/DNA Complex for Gas Sensing

Highlight

 PPy/DNA nanowires were synthesised and aligned on an oxidised silicon substrate and micro electrodes

 The chemical properties of the PPy/DNA composite were investigated using different spectroscopic and microscopic techniques

 Results revealed the formation of a supramolecular hybrid polymer containing DNA and polypyrrole.

 The conductance of the PPy/DNA film at 20 oC was of the order of 10-100 μS.

 The polymer nanomaterials were thermal stable.

 PPy/DNA can be deployed in gas sensor.

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Graphical Abstract

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Abstract

This research work is concerned with the synthesis, chemical, structural and electrical characterisation of conductive polypyrrole DNA (PPy/DNA) templated nanowires for their possible application as gas sensors. The composite is based on conductive polymer (Polypyrrole) created using a simple and low cost fabrication method that applied DNA as a template on which to carry out the polymerisation. The PPy/DNA nanowires are synthesised in solution and aligned on an oxidised silicon substrate and micro electrodes by the molecular combing method that relies on a combination of fluid flow and surface tension forces for chemical, structural and electrical characterisation respectively. The chemical properties of the PPy/DNA composite were investigated using different spectroscopic techniques such as Fourier Transform Infrared (FTIR) spectroscopy, Ultra-Violet Visible (UV-Vis) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) were used to characterise the dimension. Results from the characterisation revealed the formation of a supramolecular hybrid polymer containing DNA and polypyrrole. The polypyrrole DNA templated structures, revealed an average height of 1.60 nm for free DNA and 9-10 nm for PPy/DNA. The conductance (using two-terminal conductivity measurement) of the PPy/DNA film at 20oC was of the order of 10-100 µS. The results also demonstrate thermal stability of the polymer nanomaterials. The corresponding Arrhenius plot of the conductance of the PPy/DNA nanowires displays the temperature dependence of the conductance with activation energy < 1 eV. These results demonstrate the possible application of PPy/DNA in gas sensor.

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