Thin structures of alternating magnetic and nonmagneticlayers with a total thickness of a few hundred nanometersexhibit a phenomenon known as giant magnetoresistance.The resistance of microfabricated giant magnetoresistors(GMRs) is dependent on the strength of an externalmagnetic field. This paper examines magnetic labelingmethodologies and surface derivatization approachesbased on protein-protein binding that are aimed atforming a general set of protocols to move GMR conceptsinto the bioanalytical arena. As such, GMRs have beenused to observe and quantify the immunological interaction between surface-bound mouse IgG and
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-mouse IgGcoated on superparamagnetic particles. Results show theresponse of a GMR network connected together as a setof two sense GMRs and two reference GMRs in a Wheatstone bridge as a means to compensate for temperatureeffects. The response can be readily correlated to theamount of the magnetically labeled
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-mouse IgG that iscaptured by an immobilized layer of mouse IgG, thepresence of which is confirmed with X-ray photoelectronspectroscopy and atomic force microscopy. These results,along with a detailed description of the experimentaltesting platform, are described in terms of sensitivity,detection limits, and potential for multiplexing.