Electrochemical sensing
SPR can combine with electrochemistry, measure catalytic reaction, surface electric exchange, and develop electrochemical biosensor.
Combination of SPR and electrochemistry in life science
SPR method can be combined with a variety of electrochemical techniques to simultaneously collect optical and electrochemical real-time data from the same reaction. It can be used to measure a variety of electrochemical methods, such as potentiometer, galvanometer or impedance spectroscopy. A potentiometer can be used to cause surface reactions (electrochemical exchange) and can be used for detection.
Five typical research areas to combine electrochemistry and SPR:
1. Develop a simple electrochemical sensor device
2. Support lipid membrane quality assessment
3. Research on biocatalysis
4. Electrical reaction and functional biomaterials
5. Real time detection of concept changes
Five reasons for choosing SPR:
1. Surface modification
2. Any type of test
3. Any sample
4. Easy to verify
5. Microfluidic material test
Five key questions about electrochemical biosensors that SPR can answer:
1. How fast do molecules bind to different surfaces?
2. What is the best surface of my biosensor?
3. How about my test in serum, saliva, seawater or urine?
4. Is the biosensor I designed better than the former one?
5. Which coating can prevent the sample from adsorbing on my microfluidic channel?
Polymer collapse due to changes in pH or potential
Conductive polymers (CP) are used as materials in drug delivery systems, microelectronics, photonics and biomedical engineering. The CP polymer poly (3,4-ethylenedioxythiophene) (PEDOT) is deposited on the slide of the sensor, on which is a polyacrylic acid brush, which is a promising biological interface material.
Surface Plasmon resonance (SPR) was utilized to follow PAA polymer brushes swelling and collapse caused by pH or electric potential change. SPR with electrochemical cell was utilized to form potential change to the conductive sensor surface. Multi wavelength SPR measures whole SPR curve with two different wavelength and this can be utilized to calculate deposited layer thickness.
On the slide of the sensor, there are 18 nm thick pbredot layer and 15 nm thick film layer. As expected, bredot-g-paa showed pH sensitivity. In acidic environment (pH4), the collapse of the American society polymer brush resulted in a decrease in the thickness of the coating and an increase in the refractive index of the brush. Due to the oxidation of the conducting polymer, the change of potential also seems to lead to the destruction in the basic environment.
