Subwavelength optical probes for sensitive analysis

Near-field optics has been utilized for a variety of applications. Using near-field optical probe and microscopy, we have devised a method to introduce a near-field probe into live cultured vascular smooth muscle cell and NG108-15 neuroblastoma cells. We have effectively monitored cellular responses, with excellent spatial and fast temporal resolutions, to drug stimulation. Near-field optical probes enable the visualization of functional response in living cells. We have also nanofabricated the first single molecule optical probe. A single dye molecule, carbocyanine dye C18, is immobilized on a near-field optical probe by physical immobilization. We are able to control the preparation process by selecting the dye molecule concentrations and the interaction times of the probe with the DiI solution. The single DiI molecule probe's optical and spectroscopic properties have been characterized. Photobleaching of a single DiI molecule probe occurs as a discrete and total extinction of its fluorescence. We have also developed ultrasensitive detection schemes using near-field optical probes. Biomolecule immobilization has been carried out on optical fiber probes. Ultrasensitive biochemical sensors for glutamate and lactate have been prepared and characterized.