An immunosensor based on a Love-wave device and a PDMS microfluidic chip has been developed to detect potentially pathogenic microorganisms in real time. In order to characterize and test the immunosensor, the M13 bacteriophage has been chosen as a model of microorganism. The M13 was detected with the mouse monoclonal antibody, anti-M13 (AM13), which has been immobilized on the Love wave-device. The immunoassay has been carried out in a dynamic mode (continuous flow) through microchannels with the goal of obtaining a short response time in detecting a small volume of a sample of M13 bacteriophage. The concentrations of the bacteriophage have been varied between 5 × 108 pfu ml−1 and 2 × 1010 pfu ml−1, a range for which a fast detection and a favorable discrimination among concentrations have been achieved. The AM13 has been also used as a secondary antibody in order to measure lower concentrations such as 5 × 107 pfu ml−1.
The Double-Layer Agar technique has been used to quantify, as plaques-forming unit (pfu), the number of M13 bacteriophage in the initial sample as well as those linked to the sensor surface during the detection. Finally, the number of bacteriophage was estimated by calculating the mass sensitivity. The values obtained in both procedures have been very similar.
