A novel template guided enzymatic approach has been developed to synthesize optically active conducting polyaniline (PANI) nanocomposites in the presence of H2O2 as an oxidant, using (+) and (-) 10-camphorsulfonic acid (CSA) as a dopant and chiral inductor. The formation of chiral polyaniline in the nanocomposites was confirmed by circular dichroism (CD). Interestingly, the CD spectra of nanocomposites formed either with (+) or with (-) CSA show the enzyme itself plays a critical role in controlling the stereospecificity of the polyaniline (PANI) in the nanocomposite. The enzyme used for the polymerization of aniline in the nanocomposite was horseradish peroxidase (HRP). It was shown that this enzyme prefers a specific helical conformation, regardless of whether induced chirality in the complex CSA-aniline is from (+) or (-) CSA. UV-vis spectra show that the polyaniline is in the conducting form, and transmission electron micrographs (TEM) show that the nanocomposites are dispersed nicely with particle size dimensions in the range of 20-50 nm. Electron diffraction patterns of these chiral polymer nanocomposites suggest that these nanocomposites are in both crystalline and amorphous states.

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A biocatalytic approach has been developed to synthesize conducting polyaniline (PANI) nanoparticles. The method involves the formation of nanocomposites of PANI and poly(acrylic acid) (PAA) by polymerizing aniline (AN)-camphorsulfonic acid (CSA) macromonomer (AN/CSA) using a biocatalyst in the presence of template PAA. The second step involves the separation of PANI polymers from PAA and CSA in the nanocomposites. The formation of PANI nanoparticles by this two-step approach is studied by transmission electron microscopy (TEM). High-resolution solution 13C NMR and UV/visible spectroscopic techniques have been used to characterize the formation of conducting PANI chains by the enzymatic method.

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