Nano- and micro-plasmonics; towards scanning probe SPR microscopy and plasmonic sensors integrated to multi-well plate readers

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The research program aims at developing bioanalytical tools, based on the properties of surface plasmon resonance (SPR) for the detection of biomarkers. Two main objectives are motivating the direction of the program: 1) the development of multiplexed bioanalytical tools for the detection of a panel of biomarkers and 2) establishing an analytical technique capable of measuring with spatial resolution the concentration of extracellular proteins involved in the signaling mechanism of cancer. The recent developments in nano- and micro-plamonics enable new opportunities in optical biosensing, which fulfills the requirements of developing these important bioanalytical tools. Thus, research will be performed to integrate nano-plasmonic sensors based on nanohole arrays with multi-well plates. Nanohole arrays exhibit high sensitivity to biomolecules, are analyzed with a simple absorbance measurement and are suited for the integration into a 96-well array format. Thereby, the quantification of several chemokines will be accomplished within minutes. This technique is not restricted to the analysis of chemokines and could be applied to other panels of biomarkers. Chemokines are messenger proteins, which exhibit high levels in cancer patient's serum and may be involved in cancer growth and metastasis. Since their role is not perfectly understood in cancer growth and metastasis, a tool that can detect their presence and concentration in the extracellular matrix could help elucidate their function. Thus, scanning probe SPR microscopy will be developed to measure with spatial resolution the concentration of chemokines released by healthy and cancerous cells. Scanning probe SPR microscopy, i.e. a SPR micro-sensor on an AFM tip, is based on the properties of metal films of micrometer length. These micro-plasmonic structures exhibit sensitivity to refractive index and can be applied to detect chemokines using standard principles of SPR biosensing. Immobilizing an antibody selective for a chemokine on the gold-coated AFM tip aims at the quantification of chemokines with sub-cellular resolution with scanning probe SPR microscopy.