Preparation of Fe3O4@C@CNC multifunctional magnetic core/shell nanoparticles and their application in a signal-type flow-injection photoluminescence immunosensor

Abstract

We describe here the preparation of carbon-coated Fe3O4 magnetic nanoparticles that were further fabricated into multifunctional core/shell nanoparticles (Fe3O4@C@CNCs) through a layer-by-layer self-assembly process of carbon nanocrystals (CNCs). The nanoparticles were applied in a photoluminescence (PL) immunosensor to detect the carcinoembryonic antigen (CEA), and CEA primary antibody was immobilized onto the surface of the nanoparticles. In addition, CEA secondary antibody and glucose oxidase were covalently bonded to silica nanoparticles. After stepwise immunoreactions, the immunoreagent was injected into the PL cell using a flow-injection PL system. When glucose was injected, hydrogen peroxide was obtained because of glucose oxidase catalysis and quenched the PL of the Fe3O4@C@CNC nanoparticles. The here proposed PL immunosensor allowed us to determine CEA concentrations in the 0.005–50 ng·mL-1 concentration range, with a detection limit of 1.8 pg·mL-1.

Magnetically Encoded Luminescent Composite Nanoparticles through Layer‐by‐Layer Self‐Assembly

“…Recently, considerable effort has been devoted to the design of fluorescent magnetic multifunctional nanoparticles/nanocomposites (FMMNPs) that could be used in bioanalysis, [1] cell imaging, [2,3] drug delivery, [4] and therapy. [5] Luminescent materials, such as organic dyes, [6,7] fluorescent proteins, [8] upconversion phosphors, [9] and quantum dots (QDs), [10] have been employed for the construction of FMMNPs.…”