Long-range surface plasmons for sensitive detection of bacterial analytes

We report a novel prism-coupled surface plasmon resonance (SPR) biosensor based on special surface plasmon (SP) mode referred to as long-range surface plasmon (LRSP). Utilization of LRSP in prism-coupled SPR sensor offers several advantages in comparison with SPR sensors with conventional SPs (cSP) such as extended probe depth of LRSP mode into sensed dielectric and higher sensitivity to the bulk refractive index (RI) changes. The LRSP-supporting multilayer structures and prototype of the sensor setup were prepared. Performance of the LRSP-based sensor was compared to that of the cSP-based sensor in model experiments. LRSP-based sensor was determined to be almost 8 times more sensitive to sample RI changes than the cSP-based sensor. In addition, LRSP-based sensor responses were up to 2.5 and 5.5-fold greater than cSP-based sensor responses for latex beads and the bacterium E. coli HB101P, respectively.