Nanoplasmonics and surface enhanced spectroscopy

Surface plasmon resonance in Aluminum nanofilms:    prospects of biochemical applications
Shynkarenko O.V. 1, Beketov G.V. 1, Apatska M.V.1
1 V.E. Lashkaryov Institute of Semiconductor Physics of the NAS of Ukraine,
Prospect Nauki,41, Kyiv-03028, Ukraine.
E-mail: o.v.shynkarenko@gmail.com

The sensing performance of aluminum (Al)-based surface plasmon resonance (SPR) sensor operating at the 405 nm wavelength is evaluated. SPR lies at the core of surface sensitive techniques intended for real-time monitoring of biomolecular interactions. Typically, the SPR instruments are based on the Kretschmann configuration that uses the total internal reflection prism for excitation of surface plasmons in metal nanofilms deposited over a transparent substrate [1]. Presently, the most commonly used metal for SPR applications is gold (Au) owing to its good plasmonic properties at λ≥550nm and high chemical stability.
On the other hand, much attention has now been paid to the plasmonic applications of aluminum, which has high resonance characteristics in the wavelength range shorter than 500 nm down to deep ultraviolet region [2]. In particular, the Al-based SPR sensor at λ = 405 nm is not inferior in sensitivity to the Au-based sensor at λ = 632.8 nm. The expected advantages of using Al in SPR biosensors are the possibility of ensuring high adhesion of the metal film to the glass substrate without applying an additional adhesive interlayer and radically simplifying the immobilization of biomolecules on its surface. For Al, a promising immobilization technique is based on the chemical modification of the native aluminum oxide by the glutar aldehyde commonly used for cross linking protein macromolecules.
This study addresses several aspects of Al-based SPR sensors relevant to biochemical applications. They include the deposition technology for formation of Al nanofilms (d~20 nm) on the surface of glass substrates, characterization of their resonant properties, adhesion to the substrate, chemical stability, and efficiency of biomolecule immobilization techniques.

1.	Raether H. Surface plasmons on smooth and rough surfaces and on gratings//Springer tracts on modern physics.-111.-136 p.
2.	 Davy G.,  Gray S.K. Aluminium plasmonics//J.Appl.Phys. D,-2015. -48, N 18.-P. 184001(14pp.).