A novel method for the synthesis of nano size molecularly imprinted poly(acrylic acid) (PAA) by reverse microemulsion technique has been reported. Molecularly-imprinted PAA were also synthesised by bulk polymerisation. Levofloxacin (LOfx) (S ofloxacin) was used as the template for imprinting. Scanning electron micrograph and dynamic light scattering profile revealed that emulsion polymerisation resulted in nano size molecularly-imprinted polymer (MIP) with narrow size distribution whereas bulk polymerisation resulted in irregular shaped micron size particles. Rebinding of LOfx was highest for nano MIPs as compared to micron MIPs and the non-imprinted polymers (NIP). Imprinting factor which indicates selective binding capacity was maximum for the nano system both in water as well as in acetonitrile. Circular dichroism spectroscopy showed that nano and micron size MIPs could selectively bind to chiral LOfx from its racemic mixture (R, S ofloxacin). However, selectivity of nano MIPs was superior to micro MIPs. TLC plate prepared using nano MIP as the stationary phase could also isolate LOfx from Ofx as two distinct spots on the TLC plate, well separated spots were not visible when microsize or non-imprinted polymers were used as the stationary phase.
Keywords: poly(acrylic acid), PAA, nano MIP, ofloxacin, levofloxacin, chiral separation