Polynucleotide-functionalized gold nanoparticles as chemiresistive vapor sensing elements

Chemiresistive vapor sensors combining sensing capabilities of functionalized gold nanoparticles and DNA have been investigated. The sensors are made by depositing DNA-functionalized gold nanoparticles onto microfabricated electrodes and subsequent drying to obtain a nanocomposite film. Comparisons are made between DNA-AuNP sensors and alkanethiol-AuNP sensors, revealing both similarities and differences. The sensors behave like alkanethiol-AuNP sensors in areas of sensitivity, reversibility, and response patterns. However, DNA-AuNP sensors are different in several ways. At high analyte vapor concentrations, the sensors response pattern towards water vapor is distinctively different from those towards organic vapors. At low analyte vapor conentrations with fixed relative humidity, a dual mechanism leads to peak response at intermediate humidity. In addition, the sensors reveal length-dependent and sequence dependent response patterns which facilitate distinguishability of vapor analytes. With this concept, vapor identification capabilities of nanoparticulate chemiresistive sensors can be further enhanced.