A fibrinogen biosensing platform based on plasmonic Ga nanoparticles and aminosilane–titanate antibody trapping

Abstract

The era of personalized medicine calls for rapid detection of key biomolecules, such as serum proteins, as general indicators of a healthy/sickness state. The fabrication, biofunctionalization and calibration of a fibrinogen biosensing platform based on plasmonic gallium nanoparticles are detailed in the present work. The first step consisted in the deposition of Ga nanoparticles on Si substrates by means of Joule-effect thermal evaporation technique. A distribution of nanodroplets could be evidenced by scanning electron microscopy. The biofunctionalization of the samples was carried out using aminosilane–titanate thin hybrid layers prepared by a sol–gel route. The integration of functional amino groups could be confirmed by spectroscopic methods. Then, in order to sensitize the platform surface to fibrinogen, specific immunoglobulins have been immobilized. We monitored the plasmon wavelength changes along the fabrication cascade and during detection assays with calibrated fibrinogen solutions in phosphate-buffered saline. From the ellipsometric analysis, three operational ranges as a function of fibrinogen concentration can be identified, with an out-of-range response for low concentration, a linear response behaviour in the 1–10 µM healthy range and a tendency to saturation at high concentration.