@article {19829, title = {Development of label-free plasmonic Au-TiO2 thin film immunosensor devices}, journal = {Materials Science \& Engineering C}, volume = {100}, year = {2019}, month = {2019-02-13 00:00:00}, pages = {429-432}, abstract = {

This work reports on the development of a label-free immunosensor technology, based on nanoplasmonic Au-
TiO2 thin films. The Au-TiO2 thin films were prepared by cost-effective reactive DC magnetron sputtering,
followed by a thermal annealing procedure. The latter promoted the growth of the Au nanoparticles throughout
the TiO2 matrix and induced some morphological changes, which are the base for the immunosensor device
functionality. A posterior plasma etching treatment was required to partially expose the nanoparticles to the
biological environment. It gave rise to a 6-fold increase of the total area of gold exposed, allowing further
possibilities for the sensor sensitivity enhancement. Experimental results demonstrated the successful functionalization
of the films{\textquoteright} surface with antibodies, with the immobilization occurring preferentially in the exposed
nanoparticles and negligibly on the TiO2 matrix. Antibody adsorption surface coverage studies revealed antibody
low affinity to the film{\textquoteright}s surface. Nevertheless, immunoassay development experiments showed a strong and
active immobilized antibody monolayer at an optimized antibody concentration. This allowed a 236 signal-tonoise-
ratio in a confocal microscope, using mouse IgG and 100 ng/ml of Fab-specific anti-mouse IgG-FITC
conjugated. Label-free detection of the optimized antibody monolayer on Au-TiO2 thin films was also tested,
revealing an expected redshift in the LSPR band, which demonstrates the suitability for the development of costeffective,
label-free LSPR based immunosensor devices.

}, keywords = {Antibody immobilization, Immunosensor, Localized surface plasmon resonance, Nanoplasmonic Au-TiO2 thin films, plasma treatment}, issn = {-}, doi = {10.1016/j.msec.2019.03.029}, author = {Barbosa, A. I. and Borges, J. and Meira, D. I. and Costa, D. and Rodrigues, M. S. and Rebelo, R. and Correlo, V. M. and Vaz, F. and Reis, R. L.} }