Study of Label-Free Detection and Surface Enhanced Raman Spectroscopy (SERS) of Fibrinogen Using Arrays of Dielectric Core-Metal Nanoparticle ShellH Awad1, N Waly1, T Abdallah1, S Negm2 and H Talaat1*
- *Corresponding Author:
- Hassan Talaat
Department of Physics
Faculty of Science, Ain Shams University
Abbassia, Cairo, Egypt
E-mail: [email protected]
Received date: November 04, 2015; Accepted date: November 24, 2015; Published date: November 30, 2015
Citation: Awad H, Waly N, Abdallah T, Negm S, Talaat H (2015) Study of Label- Free Detection and Surface Enhanced Raman Spectroscopy (SERS) of Fibrinogen Using Arrays of Dielectric Core-Metal Nanoparticle Shell. J Anal Bioanal Tech S13:010. doi:10.4172/2155-9872.S13-010
Copyright: © 2015 Awad H, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Label-free detection using arrays of SiO2 nanospheres (of diameters ~500 nm) core and gold nanoparticle seeding (~4 nm) shell, with additional gold electroplated films were used as biosensors for adsorption of human fibrinogen. Also, surface enhanced Raman spectroscopy (SERS) of fibrinogen was studied as a function of the thickness of the electroplated film. It is observed that the extinction spectra of these arrays show multiple extinction peaks resulting from the interference of beams reflected between the flat substrate and the surface of the dielectric spheres as reported in the literature. There is an increase in the peak intensity and a red shift with increasing plating time. The sensitivity of these arrays to the adsorption of fibrinogen was obtained from the further red shift in the extinction spectra. SERS of fibrinogen shows an increase in the Raman bands with the time of electroplating up to a surface roughness of mean value ~1.35 nm (measured by scanning tunneling microscopy (STM)). This was followed by a decrease in the intensity of peaks with more increasing electroplating. Similar SERS results were obtained of the inorganic dye cresyl violet (CV). These results are explained in terms of interplay of the surface field enhancement due to the growth in the nanoparticles size and the resulting hotspot effects and the reduction due to the increase in the metal shell thickness.