Electroconductive Green Metal-polyaniline Nanocomposites: Synthesis and Application in Sensors

Polyaniline (PANI) is one of the most extensively used conducting polymer due to its fascinating properties including conducting, thermal, optical, magnetic and electrochemical properties, simple synthesis procedure and low cost of monomer. It has attracted major attention in a variety of applications including electrochemical sensors, catalysts, supercapacitors and biosensors. However, its limitations such as insolubility in common solvents, low process-ability and poor mechanical properties have led to the development of new approaches to improve it properties. Metal nanoparticles (MNPs) such as silver, gold, copper and palladium have been combined with PANI to improve on its properties which has led to a new class of materials known as metal/PANI nanocomposites. These hybrid nanocomposites incorporate advantages of both MNPs and polymers which effectively improves the properties of the individual materials. Various synthesis techniques including in situ polymerization, ɤ-radiolysis, electrodeposition, complexation, vacuum deposition and interfacial polymerization have been used in the formation of metal/PANI nanocomposites. These nanocomposites have been used in various sensor and biosensor applications due to their excellent conductivity, ease of synthesis, excellent redox potentials, chemical and thermal stability. This review highlights the various metal/PANI nanocomposites, their various synthesis techniques and their application in sensors and biosensors. The importance of these nanocomposites in sensing and signaling various toxic heavy metals such as mercury, lead and silver and toxic gases such as hydrogen sulphide, ammonia and chloroform has been discussed. In addition the review covers the applications of metal/PANI nanocomposites in biosensor systems for the detection of glucose, DNA, protein, cholesterol, drugs and hydrogen peroxide.