Multimodal nanocomposite probes (nanoparticle assemblies that enable imaging by two or more techniques) have become increasingly prevalent over the past decade. Of these, magnetic particles with fluorescent probe are receiving the most attention due to their ability to combine two widespread techniques, magnetic resonance imaging (MRI) and confocal or dark-field microscopy, which are complementary in terms of three-dimensional imaging capability and spatial resolution, respectively. The metallic crystals are either directly functionalized with luminescent dyes, or the dyes are embedded in a surrounding silica matrix. Organic dyes are employed most commonly in these assemblies due to their commercial availability and high quantum yield. Minimization of internanoparticle luminescence quenching is important. Decreased luminescence of organic dyes is originated with the iron oxide nanoparticles.Trypsin is a serine protease found in the digestive system of many vertebrates, where it hydrolyses proteins. Trypsin is produced in the pancreas as the inactive proenzyme trypsinogen. Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine, except when either is followed by proline. It is used for numerous biotechnological processes. So, trypsin sensing is greatly important.Herein, we used magnetic particles (MPs; Fe3O4@NH2) with conjugated polymer dots coated with poly-L-argine (CPdot@p-arg) for trypsin sensing. When the trypsin was added in MPs and CPdot@p-arg aqueous solution, p-arg was hydrolyzed, and then CPdots was aggregated with MPs due to surface charge interaction. As the result, CPdots was removed by MPs with magnetic field, and then fluorescence of solution was quenched.

Multimodal trypsin sensing using charge attraction and repulsion of oligopeptide coated-conjugated polymer dots and magnetic particles

247th National Meeting (2014)

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