Localized surface plasmon-enhanced nanosensor platform using dual-responsive polymer nanocomposites.

The fast and accurate identification of unknown liquids is important for the safety and security of human beings. Recently, sensors based on the localized surface plasmon resonance (LSPR) effect demonstrated an outstanding sensitivity in detecting chemical and biological species. In the present study, we suggest that a dual-responsive nanocomposite composed of two polymer brushes and two noble metal nanoparticles provides a significantly improved selectivity (improvement of a factor of 30 in figure-of-merit) for distinguishing diverse liquids compared to a single-responsive LSPR sensor. The dual-responsive LSPR sensor platform was realized by the synergic combinations of two hydrophobic and hydrophilic polymer brushes, which respond differently depending on the degree of interaction between the polymer brushes and the surrounding liquids. Moreover, the mixing ratio of two solvents can also be estimated with high accuracy using the dual-nanocomposite LSPR sensor, suggesting that this approach would be highly practical for in situ process monitoring systems that can instantly detect the change of solvent composition.