Kinetic analysis of nanoparticle-protein interactions using a plasmon waveguide resonance.

A plasmon waveguide resonance (PWR) sensor is proposed for studying the interaction between gold nanoparticles and proteins. The ability of the PWR sensor to operate in both TM and TE Polarizations, i.e. its polarization diversity, facilitates the simultaneous spectroscopy of the nanoparticles surface reactions using both polarizations. The response of each polarization to streptavidin-biotin binding at the surface of gold nanoparticles is investigated in real time. Finally, using the principles of multimode spectroscopy, the nanoparticle's surface reactions are decoupled from the bulk solution refractive index variations. Schematic diagram of the NP-modified PWR sensor.

Leukemic marker detection using a spectro-polarimetric surface plasmon resonance platform.

In this paper, we present a proof of concept screening for monoclonal immunoglobulin as a leukemia tumor marker using a surface plasmon resonance (SPR) bio-sensing platform. This screening method is based on measurements of immunoglobulin levels in human serum and the determination of the relative concentrations of kappa and lambda light chains. The kappa/lambda ratio is used to determine the presence of monoclonal immunoglobulin. Tests have been performed using standard solutions of immunoglobulins and serum samples from patients with known leukemic diagnoses. This platform has a resolution of 5×10(-7) refractive index unit (RIU) per channel, which is up to 10 times better than other SPR imaging systems for multi-sensing applications. The results obtained with this technique are in agreement with those acquired using conventional methods for immunoglobulin detection, indicating that our polarimetric SPR platform should be suitable for a cheap and efficient tool for early leukemia biomarker screening and monitoring applications.

Self-referenced spectroscopy using plasmon waveguide resonance biosensor.

A plasmon waveguide resonance (PWR) sensor is designed, fabricated, and tested for self-referenced biosensing. The PWR sensor is able to support two different polarizations, TM and TE. The TM polarization has a large sensitivity to variations in the background refractive index while the TE polarization is more sensitive to the surface properties. The ability of the PWR sensor to simultaneously operate in both TM and TE modes is used to decouple the background index variations (bulk effects) from the changes in adlayer thickness (surface effects) via multimode spectroscopy. To benchmark the performance of the PWR, a conventional surface plasmon resonance (SPR) sensor is fabricated and tested under the same conditions.

An improved refractive index sensor based on genetic optimization of plasmon waveguide resonance.

Plasmon waveguide resonance (PWR) sensors are particularly useful for biosensing due to their unique ability to perform sensing with two different polarizations. In this paper we report a comprehensive performance comparison between the surface plasmon resonance (SPR) sensor and the PWR sensor in terms of the sensitivity and the refractive index resolution. Both sensors were optimized using a genetic algorithm to acquire their best performance for bulk sensing applications. The experimental results show that the PWR sensor has a refractive index resolution of 5 × 10(-7) RIU which is 6 times smaller than that of the optimized SPR sensor. The TE polarization in the PWR sensor has a resolution of 1.4 × 10(-6) RIU which is smaller than the SPR sensor. The polarization diversity in the PWR sensor is another advantage which can be used to improve the measurement reliability.

Polarimetric total internal reflection biosensing.

In this paper, a concept of polarimetric total internal reflection (TIR) biosensor based on the method of temporal phase modulation is presented. Measurements of the phase difference between s- and p- polarized light combined with their amplitudes allow simultaneous detection of the bulk refractive index and thickness of the surface biofilms. Obtained experimental sensitivity is better than 10(-5) in terms of refractive index unit and 0.5 nm in biolayer thickness. Relatively simple technological implementation of the TIR sensors on the base of inexpensive and transparent substrates opens a number of novel applications in biosensing and microscopy.