Selective Terpene Vapor Detection Using Molecularly Imprinted Polymer Coated Au Nanoparticle LSPR Sensor

A localized surface plasmon resonance sensor based on molecularly imprinted polymer (MIP) coated Au nanoparticle (AuNP) was developed to selectively detect alpha-pinene vapor. AuNPs were deposited on glass slides via Au ion sputtering method. The MIP was synthesized using methacrylic acid as monomer, ethylene glycol dimethylacrylate as cross-linker, and alpha-pinene as template. Adsorption characteristics of MIP powder and coating films were evaluated using gas chromatography mass spectrometry. The influence of molar ratio of template (alpha-pinene) to monomer on the absorption characteristics of MIP film was investigated. The largest affinity absorption amount of polymer film was achieved when the molar ratio of template to monomer was 1:4. Prepolymerized MIP mixture was spin coated on the sputtered AuNPs. The results showed that plasmon resonance peak in spectrum and the refractive index sensitivity depended on the polymer layer thickness. Better sensitivity and selectivity of MIP coated AuNPs sensor were realized at the spin coating speed about 1400 r/min. The real-time responses of alpha-pinene imprinted polymer coated AuNP sensor to three terpene vapors: alpha-pinene, limonene, and gamma-terpinene were verified to be selective, rapid, and reversible.