N-SHEAD · Nanoarrays: Self-assembled Hotspots for Enhanced Analyte Detection

Nanoarrays: Self-assembled Hotspots for Enhanced Analyte Detection

The three most significant challenges facing biosensing are inaccuracy, insensitivity, and low-throughput detection. One technique that is capable of facing these challenges is SERS which has demonstrated potential for extreme sensitivity and rapid, multiple-analyte detection within complex mixtures. Early stage diagnosis of disease requires the detection of trace amounts of analyte in multi-component biological samples (blood, urine, saliva). It is therefore particularly important for sensors to be reach low detection limits. The objective of the action was to exploit the self-assembly of nanoparticles (NPs) at liquid-liquid interfaces (LLI) to produce a 2D homogeneous array of plasmonic NPs for ultrasensitive surface enhanced Raman (SERS) sensing. To achieve this we had several goals; to assemble spherical and shaped plasmonic NPs at the LLI and to test their Raman response and potential for sensing of colorectal cancer. Conclusions: We investigated the assembly of spherical and shaped NPs at the LLI, working towards more control over their assembly and understanding their structure. Through in situ manipulation of the NP structure and spacing within the film we were able to observe the direct effects of plasmon coupling on the Raman and optical response of the arrays. Through a collaborative project, NPs were driven to the LLI through electrochemical means. The process was reversible. These NPs were only 16 nm in diameter but there is potential to apply this research to larger NPs more suitable for SERS experiments. A NP immunoassay was constructed for the detection of carcinoembryonic antigen (CEA), a biomarker for the presence of colorectal cancer. We were able to detect down to 10 ng/mL (a concentration above 10 ng/mL indicates that colorectal cancer may be present). The detection was specific, with no signal seen in the control sample. The duration of the test was also faster than conventional immunoassays (requires two incubation steps of 24 h). We were able to detect CEA after only 2 h incubation on both steps.

Data: CORDIS, © European Union