Multiple bio-responsive polymer dispersed liquid crystal composites for sensing applications

Abstract

Polymer dispersed liquid crystal (PDLC) composites were prepared by the encapsulation of cholesteryl acetate (L-ChAc) in polyvinyl alcohol boric acid (PVAB) by microemulsion technique. The supramolecular and morphological peculiarities of the resulted composites were analyzed by polarized optical microscopy, fluorescence microscopy and scanning electron microscopy respectively. The thermal behavior of the systems was evaluated by differential scanning calorimetry and the surface characteristics in terms of wettability and surface free energy were calculated based on contact angle measurements. Circular dichroism was further used to evidence the chiroptical properties of the studied PDLCs and to have an insight on the potential interactions between the components. The ability of the composites to act as sensors for different blood analytes was preliminary tested by POM. The results indicated that PVAB facilitated a uniform distribution of the cholesteric liquid crystal as micrometric droplets with narrow polydispersity and planar anchoring. The obtained PDLCs proved moderate wettability and they showed a selective responsiveness for L or D sugars, amino acids and DNA. All these results indicated the new polymer dispersed liquid crystal systems as promising materials for biosensors building.