Comparative SERS study carried out on unsilanized and silanized oxidized porous silicon surface coated by small gold nanoparticles

Abstract

International audiencePorous silicon (PSi) was formed by electrochemical anodization and was oxidized before silanization and immersion in colloidal gold nanoparticles (5 nm size) solution. The oxidized PSi (OPSi) coated with nanoparticles was used as Surface Enhanced Raman Scattering (SERS) substrate, where Bovine Serum Albumin (BSA) was used as a target molecule. Also, Rhodamine 6G (R6G) dyes were used to confirm the SERS efficiency. Firstly, the bio-conjugation between protein and gold nanoparticles (GNP) was investigated by Localized Surface Plasmon Resonance (LSPR) spectroscopy. Then a comparative SERS study from silanized and unsilanized OPSi was performed and showed a good vibrational BSA bands resolution with the unsilanized one. The silanized surface did not show any improvement on the SERS enhancement of the BSA due to the interferences between the vibrational modes of 3-aminopropyltriethoxysilane (APTES) and BSA. Furthermore, we have investigated the BSA solution pH effect on the SERS results in the case of unsilanized OPSi surface. The results prove the efficiency of the SERS substrate at pH= 4.9, corresponding to BSA iso-electric point. A detection limit of about 10-8 M was obtained for both BSA and R6G molecules

Magnetic–plasmonic Ni@Au core–shell nanoparticle arrays and their SERS properties

“…As it can be seen, the typical peaks of R6G molecules are at 613 cm À1 , 771 cm À1 , 1198 cm À1 , 1308 cm À1 , 1360 cm À1 , 1504 cm À1 , and 1652 cm À1 corresponding to the C-C-C ring in-plane vibration mode, C-H outof-plane bend mode, C-C stretching mode, aromatic C-C stretching mode, C-N stretching mode, aromatic C-C stretching mode and aromatic C-C stretching mode, respectively. 41,42 Obviously, the Ni 50 @Au 50 NPA substrate has the most signicant Raman enhancement than other substrates. The spectrum of Ni 80 @Au 20 NPA substrate shows the similar mode features and slight increase in the absorption bands, but weaker characteristic SERS peaks are generated.…”

Porous Silicon-Based Photonic Biosensors: Current Status and Emerging Applications

“…As already mentioned, one of the most advantageous properties of PSi is its large surface area (up to 800 m 2 g –1 ) and high internal volume, allowing for numerous biomolecular interactions to occur over a small working area. Furthermore, PSi can serve as a host matrix for diverse compounds and nanomaterials, including polymers, − metals, − quantum dots (QDs), − fluorescent molecules, − graphene oxide (GO), − carbon nanotubes (CNTs), , and carbon dots (C-dots) . The main advantage of these PSi-based hybrid systems is that they can exhibit superior sensing performance in comparison to the individual components, such as signal enhancement, higher sensitivity, improvement of signal stability, and dual-mode detection.…”

Magnetic-plasmonic Ni@Au core-shell nanoparticle arrays and their SERS properties

“…Figure 7 shows the Raman spectra of R6G molecules with a concentration of 10 −6 M adsorbed on Au100 (spectrum (1)), Ni20@Au80 (spectrum (2)), Ni40@Au60 (spectrum (3)), Ni50@Au50 (spectrum (4)), Ni60@Au40 (spectrum (5)), Ni80@Au20 (spectrum (6)) and Ni100 (spectrum (7)) NPA substrates, respectively. As it can be seen, the typical peaks of R6G molecules are at 613 cm -1 , 771cm -1 , 1198 cm -1 , 1308 cm -1 , 1360 cm -1 , 1504 cm -1 , and 1652 cm -1 corresponding to the C-C-C ring in-plane vibration mode, C-H out-of-plane bend mode, C-C stretching mode, aromatic C-C stretching mode, C-N stretching mode, aromatic C-C stretching mode and aromatic C-C stretching mode, respectively [40,41]. Obviously, the Ni50@Au50 NPA substrate has the most significant Raman enhancement than other substrates.…”