Gold surfaces, biosensing

Localized surface plasmon (LSP) The surface plasmon (SP) cannot propagate on the surface of metallic nanoparticles and therefore, is localized and hence known as localized surface plasmon (LSP). The LSP resonance of gold and silver NPs occurs in the visible range of the spectrum, which makes these two metals particularly useful for a number of applications ranging from ultrasensitive diagnostic tools to biosensing devices. 

Figure 15. Construction and proposed operational principle for the affinity biosensor based on the avidm-biotin interaction on a gold electrode surface. (Right) Molecular models of the chemicals used for electrode construction and affinity biosensing. (Adapted from Ref. [172]).

Nowadays, the construction of electrochemical biosensors based on the use of gold nanoparticles constitutes an intensive research area because of the unique advantages that this nanomaterial lends to biosensing devices. So, gold nanoparticles provide a stable surface for immobilization of biomolecules with no loss of their biological activity. Moreover, they facilitate direct electron transfer between redox proteins and electrode materials, and constitute useful interfaces for the electrocatalysis of redox processes of molecules such as H202 or NADH involved in many biochemical reactions (1, 2). 

Another important area where gold-thiol monolayers might find promising applications is gas- and biosensing. Simple sensors sensitive to certain types of compounds, based on such detection methods as surface plasmon resonance or surface acoustic wave, have been described454,455,531-533. This type of device is usually made of a gold plate coated with a functionalized monolayer. The terminal functional group of such a monolayer is responsible for selective interactions with the analyte, and adsorption of the latter is then detected by the appropriate method. 

Balamumgan, S., Obubuafo, A., Soper, S. A., McCarley, R. L., Spivak, D. A. (2006). Designing highly specific biosensing surfaces using aptamer monolayers on gold. Langmuir 22, 6446-6453. 

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