Development of a FRET based fiber-optic biosensor for early detection of myocardial infarction

A novel optical biosensor technique is being investigated for early detection of myocardial infarction utilizing the distance-dependent chemical transduction method of fluorescence resonance energy transfer (FRET). The FRET process requires two fluorophores termed the donor and the acceptor. When in close proximity, the donor absorbs energy from the excitation source and nonradiatively transfers the energy to the acceptor, which in turn emits fluorescent energy. This distance dependent property was utilized to detect conformational changes when antibodies combine with their respective antigens. The fluorophores were conjugated to an antibody-protein A complex and then immobilized to the distal end of an optical fiber. FRET-induced changes in fluorescence were measured as the maximum areas under the donor and acceptor fluorophore emission spectrum, P1 and P2 respectively. Results showed that the addition of specific HuIgG antigen reduced the P1/P2 ratio in five of the six fibers tested. A reduction in the P1/P2 ratio indicated that the antibodies underwent a conformational change upon binding, reducing the distance between the FRET fluorophores. More experiments need to be performed to further characterize the effects of the fiber preparation, immobilization procedure, instrumental sensitivity, and fluorophores concentration on the function and calibration of FRET-based biosensors.