Surface plasmon resonance (SPR) sensing technology is widely used in the field of biosensors due to its non-marking, high-sensitivity, and non-invasive characteristics. However, SPR technology is still limited to sensing analysis in twodimensional plane, axial detection, as the key of SPR application in three-dimensional medium spatial detection, has not been well studied and solved. In an angle-interrogation SPR sensing system, the spatial characteristics of evanescent wave-dielectric interaction at multiple wavelengths are studied, and the factors affecting the spatial distribution of surface plasmon resonance are also analyzed. An axial spatial resolution method based on the particle swarm optimization (PSO) algorithm with multi-wavelength angle-interrogation structure is proposed, the refractive index distribution in axial space is determined by analyzing the characteristic SPR signal. In addition, the calculation and analysis of the applicable range of wavelengths are carried out. In the reliable spectral range of the incident light wavelength of 600-900 nm, the average error of the axial refractive index spatial resolution increases from 10-5 RIU to 10-4 RIU as the number of axial layers increases. The proposed multi-wavelength angle modulation structure analysis method based on PSO algorithm extends the SPR detection range from two-dimensional plane to three-dimensional space, which provides a new and promising analysis model for molecular biology.
A bimetallic chip was designed to improve the performance of a surface plasmon resonance (SPR) sensor based on angular interrogation, which demonstrated a relatively low noise level and a high resolution compared with a single gold chip. The calculated refractive index resolution of the bimetallic chip is 5.3 × 10-7 RIU. In addition, the electric field intensity at the surface of the chip is enhanced. This can guarantee a high sensitivity in a larger sensing region for the measurement of macromolecules, especially in the field of biological sensing. The bimetallic chip SPR sensor was combined with molecularly imprinted polymer (MIP) film as artificial receptor to detect antibiotics. The molecularly imprinted polymer was prepared by photo-polymerization of ciprofloxacin capped with itaconic acid as functional monomer on the bimetallic chip. The thickness of the MIP film was 16 ±2 nm, which was measured with a stylus profiler. The MIP exhibited high selectivity to ciprofloxacin compared with dopamine and penicillin, and the selectivity coefficients of ciprofloxacin,penicillin, and dopamine were 1, 0.22, and 0.19, respectively. The SPR response was proportional to the concentration of ciprofloxacin, the limit of detection (LOD) of which was 0.1 pM or 0.04 ppt,while the LOD for a single gold chip was 0.5 pM. The adsorption of CIP by the MIP bimetallic-coated chip was reversible. Taking the reproducibility of MIP into consideration, a combination of SPR sensing with MIP is a promising method for the detection of ciprofloxacin.
A novel electrochemical surface plasmon resonance (EC-SPR) sensor has been developed
based on the surface plasmon resonance (SPR) combined with a two-electrode electrochemical
configuration. The theory of potential-modulated for EC-SPR was described, and several factors
which can induce the change of the SPR resonance angle were revealed. Comparing with the
conventional three-electrode electrochemical system, the reference electrode has been eliminated in
this design, and the active carbon (AC) electrode employed as the counter electrode. Due to the large
specific surface area, AC presents considerable double layer capacitance at the interface of electrode
and electrolyte, which can provide a constant potential during the electrochemical reactions. Using an
angle modulation SPR sensor and the resolution of that is 5x10-6 RIU (refractive index units), a
real-time data-smoothing algorithm is adopted to reduce the noise of the data, which can guarantee an
accurate result of the resonance angle of SPR. The EC-SPR setup was used for investigating the
electropolymerization of polyaniline by applying a potential of cyclic voltammetry, both of the
electrochemical current and the resonance angle shift of SPR are recorded to monitor the growth
process of the polymer. Comparing with the three-electrode configuration, the novel AC
two-electrode system can also obtain detailed information about the polymerization process from the
resonance angle shift curves, including the change of thickness and dielectric constant, deposition and
transitions between different redox states of the polymer film. Experimental results demonstrated that
this two-electrode EC-SPR configuration is suitable for analyzing the electropolymerization process
of a conducting polymer.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.