Sensing performance of protein C immuno-biosensor for biological samples and sensor minimization.

Protein C (PC) is an important anticoagulant and antithrombotic agent in human blood plasma. PC deficiency can result in clotting complications that interfere with oxygen and nutrient transport. A fiber-optic biosensor is being developed to provide real time diagnosis of PC deficiency. The PC sensor was tested to quantify PC level in human plasma. The signal intensity obtained from the plasma sample was 30% of the buffered sample, possibly due to the increased viscosity. The feasibility of monitoring PC level in animal cell culture broth and animal milk was tested. For the cell culture broth, 80% of signal was observed. However, the decrease was consistent over the sensing range. For whole and 1:100 diluted bovine milk, the signals were 60 and 78% of buffered sample, respectively. The biosensor length was reduced from 12.5 to 6 cm with sufficient sensitivity. To increase the sensor reusability, various elution buffers were applied after each sensing. Triethylamine elution buffer provided the best sensor regeneration capability and increased the number of assays from 2.5 to 7 times for 6 cm fibers.