SPR sensor chips

Application Note: 
All functionalities are available for gold surfaces used in surface plasmon resonance (SPR) sensing. Either PEG brush or dextran base.

Surface Plasmon Resonance (SPR) is the most popular technique in bio-sensing. The chief advantage of SPR is its capability of quantitative detection in real time, with sensitivity as high as a fraction of a monolayer of small molecules and, most of all, with no need for labeling. This label-free nature has enabled SPR to be used in a wide range of bio- and chemical analysis applications, ranging from establishing the specificity of biomolecular interactions to the measurement of binding/dissociation kinetics and binding affinity. Recent development of SPR imaging in array formats has made this technique a high throughput tool. SPR is now a standard tool in drug discovery/development and in biomedical research. One critical issue in the reliable application of SPR is the need to eliminate or minimize non-specific adsorption. The SPR signal essentially measures changes of mass (more precisely refractive index) near a sensor surface (typically gold metal film). As a result, any non-specific adsorption will contribute to a false-positive signal. There is a clear requirement for a surface which minimizes non-specific interaction, maintains probe activity, and optimizes probe-target interaction. MicroSurfaces’ ZeroBkg® line of functional surfaces is ideal for meeting this requirement. Each coating consists of a high-density poly-ethylene-glycol (PEG) brush to prevent non-specific adsorption, robust bonds to the solid substrate for long term coating stability, specific functional groups for the facile immobilization of protein and other bio or organic molecules of interest, and a hydrophilic surface chemical environment for optimal target-probe interaction. We now offer the complete line of ZeroBkg® functional surfaces to SPR users. To illustrate the performance of the surfaces, we show specific adsorption on our functional SPR surfaces. Fig. 1 shows the immobilization of fibrinogen on the in-situ activated NHS surface (red). Fig. 2 shows the specific adsorption of streptavidin on the biotin-activated surface. Fig. 3 shows the specific immobilization of 6xHis-tagged green fluorescent protein (GFP) on the chelated Cu2+/PEG/Au surface. The blue curves in all three figures are controls showing the absence of nonspecific fibrinogen (Fbn) adsorption.

Fig.1 Fibrinogen binding to ZeroBkg® SPR surface with in situ NHS activation (red). The blue curve shows SPR response on the surface without NHS activation. Fig. 2 Streptavidin binding to biotin-activated ZeroBkg® SPR surface (red). The blue curve shows the resistance of the surface to nonspecific adsorption of fibrinogen. Fig. 3. SPR response (red) showing the specific adsorption of 6xHis-tagged GFP on the chelated Cu2+/PEG/Au surface. The blue curve is control showing the absence of nonspecific adsorption.

In addition to SPR sensors, our customers are also applying the ZeroBkg® surfaces on a variety of other biosensors, microfluidics, biochips, and bioMEMS devices. Tell us what you need. We will find the surface coating technology to meet your demand.


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