Detection Of Small Molecules By Automated Real-Time Surface Plasmon Resonance Based Immunosensor

CHAIN, C.; DAZA MILLONE, M.A.; RAMIREZ, E.A.; ROMANIN, D.; COCCO, M.D.; MONTOYA, J.; RUMBO, M.; DOCENA, G.; FAINSTEIN, A.; VELA, M.E.

Gotemburgo

Congreso; Biosensors 2016. 26th Anniversary World Congress on Biosensors; 2016

AbstractIn this work we describe a fully self-contained and automated portable Surface Plasmon Resonance (SPR) biosensor designed for real-time analysis of small molecules by competitive immunoassays. The system integrates pumps and valves for sample injection and sensor surface regeneration, and the automation of the optical alignment necessary for its operation. The device was tested with the model system 2,4- dinitrophenol (DNP) and monoclonal anti-DNP. With this aim, three chemical modifications of the sensor surfaces were addressed. The gold substrates were chemically modified ex situ with single (11- mercaptoundecanoic acid ?MUA-) and mixed (MUA/ dithiotreitol) self-assembled monolayers and with the combination single SAM/ tridimensional polymer (MUA/poly-L-lysine). In the sensor surfaces that do not include poli- L- lysine, serum albumin conjugated with DNP was immobilized as ligand. In the surface that included the polymer, the ligand was DNP. The detection range and sensitivity of the arrangements to measure antibodies solution as well as their capability to reveal competition between the analyte and the antibodies were addressed. Experiments showed that the arrangement that includes the mixed SAMs can detect antibodies concentrations as low as 3 nM and has the best sensitivity. Nor the single SAMs or the combination SAM/ 3D polymer can reach this performance (Figure 1). Concerning the competition, the surface covered with MUA/ poly-L-lysine can reveal almost 70 % of antibody inhibition when it is pre incubated with saturated DNP aqueous solution. The other sensor surfaces could not reveal more than 20 % of antibody inhibition in the same experimental conditions.These results suggest that the developed platform promises to be an innovative system for the detection of small molecules in diluted solutions (ppb) without the necessity of pretreatment and with rapid times of analysis.