Analytical Sciences
Online ISSN : 1348-2246
Print ISSN : 0910-6340
ISSN-L : 0910-6340
Original Papers
A Surface Plasmon Resonance Sensor for Substance P Using Gold-Modified Calmodulin and Melittin
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2005 Volume 21 Issue 12 Pages 1431-1436


A surface plasmon resonance (SPR) biosensor for the quantification of a neuropeptide substance P (SP) is described based on an inhibition assay using Au colloid-modified calmodulin (Au-CaM) and a target peptide melittin immobilized on carboxymethylated dextran. The modification of CaM with streptavidin Au colloids was achieved in a sample solution by the amine coupling method. The SPR signal sharply increased, corresponding to the formation of a Ca2+-Au-CaM-melittin complex on the sensor surface, and approached a steady state within 5 min. When SP was added to a sample solution, the SPR signal was decreased, due to the formation of a Ca2+-Au-CaM-SP complex in the sample solution. The modification of CaM with streptavidin Au colloids was effective for enhancing the SPR signal for SP. A decrease in the SPR signal was observed for SP in the concentration range from 0.10 to 5.0 µM, whose lower limit was ten-times superior to that (1.0 µM) with unmodified CaM. The response was highly selective to SP and the selectivity was in the order of SP >> neurokinin A > neurokinin B > neurotransmitters (glycine, GABA, L-glutamate, acetylcholine, norepinephrine, 5HT) ∼ substance P fragment (1 - 7). The potential use of the present sensor for the quantification of SP in mouse brain extracts is demonstrated.

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© 2005 by The Japan Society for Analytical Chemistry
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