@misc{BoeckerZybinNiemaxetal., author = {Boecker, Daniel and Zybin, Alexander and Niemax, Kay and Grunwald, Christian and Mirsky, Vladimir M.}, title = {Noise reduction by multiple referencing in surface plasmon resonance imaging}, series = {Review of Scientific Instruments}, volume = {79}, journal = {Review of Scientific Instruments}, number = {2}, issn = {1527-2400}, doi = {10.1063/1.2888527}, pages = {023110}, abstract = {The analytical performance of surface plasmon resonance imaging with charge coupled device detection can be improved significantly by splitting a macroscopic sensing surface into multiple microscopic neighboring sensing and referencing subareas. It is shown that such a multiple referencing reduces intensity fluctuations across the total sensing area and, therefore, improves the signal/noise (S/N)ratio proportional to the splitting factor. The approach is demonstrated by detection of biotin binding to a monolayer of streptavidin. An effective variation of the reflected intensity of about 10⁻⁴, which corresponds to the refraction index variation of 3 x 10⁻⁶, was detected with a S/N ratio about 10 without any temperature stabilization of the sensing area.}, language = {en} } @misc{ZybinGrunwaldMirskyetal., author = {Zybin, Alexander and Grunwald, Christian and Mirsky, Vladimir M. and Kuhlmann, J{\"u}rgen and Wolfbeis, Otto S. and Niemax, Kay}, title = {Double-wavelength technique for surface plasmon resonance measurements: basic concept and applications for single sensors and two-dimensional sensor arrays}, series = {Analytical Chemistry}, volume = {77}, journal = {Analytical Chemistry}, number = {8}, issn = {0003-2700}, doi = {10.1021/ac048156v}, pages = {2393 -- 2399}, abstract = {A new technique for on-line monitoring of analyte binding to sensor surfaces by surface plasmon resonance (SPR) detection is described. It is based on differential measurements using two wavelengths provided by two diode lasers. The technique is as simple and robust as the conventional SPR detection measuring the reflected radiation at fixed incidence angle, but it has the advantage of being nonsensitive to variations of the resonance width and providing essentially higher signal/noise ratios. The paper presents the first four channel prototype system for parallel 2D-monitoring at four different spots. One channel is always used as a reference to compensate temperature fluctuations and nonspecific adsorptions. Calibration with sucrose solutions revealed an absolute sensitivity of Δn ∼ 5 × 10-6. The new technique is tested with a biotin-streptavidin binding and with hybridization/denaturation of DNA. Biotin binding to a streptavidin monolayer is detected with a signal/noise ratio of about 5, which demonstrates the high potential of the new technique for applications in drug discovery. Applications to gene analysis are tested with short oligonucleotides of the sequences used for genotyping human hepatitis C viruses. A selective response to complementary oligonucleotides is observed. The high reproducibility in subsequent cycles of hybridization/denaturation (by formamide or by heating) points out potential applications of the technique in medical diagnostics, food industry, genomics, and proteomics too.}, language = {en} }