Recent work at Shanghai University by the Chen group was published in Microchimica Acta reporting a surface plasmon resonance biosensor for the determination of brain natriuretic peptide. Detection was accomplished by binding of the peptide to an amine functionalized aptamer probe. Pyridinium porphyrin-mediated Au nanoparticle composites were used to amplify the SPR signal. Thanks for using our Fe (III) meso-tetra(N-methyl-4-pyridyl)porphine pentachloride catalog number T40322.