Core–shell nanoparticles for gas phase detection based on silver nanospheres coated with a thin molecularly imprinted polymer adsorbed on a chemiresistor

We present a novel gas phase detection prototype based on assembling core–shell nanospheres made of a silver core and coated with a molecularly imprinted polymer (MIP) adsorbed onto an interdigitated array (IDA) electrode chemiresistor (CR). The core–shell nanospheres, AgNP@MIPs, were imprinted with linalool, a volatile terpene alcohol, as a model system. The thickness of the MIP layer was tuned to a few nanometers to enable the facile ingress and egress of the linalool, as well as to enhance the electrical transduction through the Ag core. The AgNP@MIPs were spread onto the IDA-CR modified with various positively charged polymers, by drop casting and dip-coating. The AgNP@MIPs were characterized by various techniques such as extra high-resolution scanning and tunnelling electron microscopy and X-ray diffraction. The MIP recognition event was transduced into a measurable increase in the resistance. The response to linalool exposure and removal was fast and the device was fully recovered and could be reused. Finally, the difference in the resistance change between imprinted and non-imprinted nanospheres was substantial.