Tubular optical waveguide-based particle plasmon resonance biosensor for label-free and real-time detection

A novel tubular optical waveguide-based particle plasmon resonance (TOW-PPR) device for chemical and biochemical sensing is presented. The sensor is based on intensity measurement of consecutive total internal reflections (TIRs) along the wall of the gold nanoparticles-modified glass vial at a fixed wavelength from a miniaturized light emitting diode (LED). The extinction cross-section of self-assembled gold nanoparticles on the inner wall surface of a tubular glass vial changes with different refractive indexes (RIs) of surroundings in the vicinity of nanoparticles. In comparison with other evanescent wave based optical sensors, the TOW-PPR sensor possesses merits of being a wavelength-selectable optical waveguide sensor to fit application needs, microchamber of a defined sample volume, and itself of being a mechanical support for sensor coatings. The sensor resolution is estimated to be 2.7x10-6 RIU in measuring solutions of various RIs ranging from 1.343 to 1.403 obtained by dissolving sucrose in ultrapure water with a concentration between 6.8% and 41.7%. Moreover, the TOW-PPR microchamber was chemically modified with N-(2,4-dinitrophenyl)-6-aminohexanoic acid (DNP, MW = 297.27 Da) and has been shown to be able to detect different concentration of anti-dinitrophenyl antibody (anti-DNP, MW = 220 kDa) in buffer solutions. From corresponding calibrations, a detection limit of 1.21x10-10 g/ml by DNP-functionalized TOW-PPR sensor chip for anti-DNP detection is demonstrated. The device can be simply and inexpensively fabricated, and therefore is ideally suitable for disposable plasmonic sensors, especially promising for high-throughput biochemical sensing applications.