Thin Film of Polyelectrolyte Complex Nanoparticles for Protein Sensing

Polyelectrolyte complex nanoparticles (PEC NPs) are prepared using two polyelectrolytes poly(Na-4-styrene sulphonate) (PSS) and poly(diallyldimethylammoniumchloride) (PDADMAC) at a molar mixing ratio of n(-)/n(+) approximate to 0.67 by consecutive centrifugation. PEC NPs formation is investigated through dynamic light scattering (DLS) and atomic force microscopy (AFM). Optical behaviors of PEC NPs in thin film confirmation are studied using UV-Vis and photoluminescence spectroscopy. Although absorption peaks of PSS occurs at the same position before and after the formation of PEC NPs but emission peaks are found at approximate to 278 and 305 nm whereas for pure PSS emission peaks exist at approximate to 295 and 365 nm. Hence, thin film of PEC NPs can be applied as very sensitive material for protein sensing since absorption of protein is occurred at approximate to 278 nm. Protein sensing behavior of such PEC NPs thin film is studied using photoluminescence spectroscopy.