Gold sensor chips, immobilized

Fig. 5.8 Schematic setup of the surface plasmon resonance (SPR) detection unit in a Bia-core instrument. One interaction partner is immobilized on a modified gold surface, whereas the other flows by in solution. On the other side of the sensor chip, a beam of polarized light is reflected by the gold film. The optical phenomenon SPR leads to a re-...

An immunoassay for the detection of PSA in PBS buffer based on a dualchannel SPR instrument with angular modulation (IBIS II) has been reported [24]. This work compared direct and sandwich detection of PSA on planar- and hydrogel-type sensor surfaces. Amplification with colloidal gold and latex microspheres, respectively, was employed in the sandwich assay. Sensor chips with carboxylated matrices of different thicknesses were used. Mouse monoclonal antibodies against PSA were immobilized on the both... 

Using PAA as the starting point, a self-assembly DNA-conjugated polymer was prepared for DNA chip fabrication. The amounts of ssDNA and PDPH in the polymer were determined by absorption measurements to be equivalent to 1/714 [molecule/monomerunit] and 1/46 [molecule/monomerunit], respectively. A 20-mer ssDNA as P-1 DNA and PDPH for self-assembled immobilization were covalently attached to PAA as side chains. After self-assembled immobilization of the DNA-conjugated polymer on the gold surface of a sensor, the P-1 DNA chain was hybridized to a 34-mer ssDNA as P-2 DNA, which had a sequence fully matched to the desired target DNA. Analysis of the first hybridization (between P-1 and P-2 DNA) and of the second hybridization (between P-2 and the target DNA) was done by fluorescence measurements. 

However, the study of hydrophobic proteins using Biacore systems is possible using protocols specially designed for the purpose. For example, proteins may be firstly incorporated into liposomes and then immobilized on hydrophobic sensor surfaces (Sect. 3.3). It has been reported that hpid bilayers have been tethered to a sensor surface via hydrophihc spacers immobilized on a plain gold chip into which membrane-spanning proteins are then inserted [57]. The emphasis of this technique rests on encasing sensitive protein domains within a hpid microenvironment in which they can assume a native, functional structure. 

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