Research Article Luminomagnetic Silica-Coated Heterodimers of Core/Shell FePt/Fe 3 O 4 and CdSe Quantum Dots as Potential Biomedical Sensor Caio Guilherme Secco de Souza, 1,2 João Batista Souza Jr., 2 Watson Beck Jr., 3 and Laudemir Carlos Varanda 2 1 Departamento de Qu´ ımica, Universidade Federal de S˜ ao Carlos (UFSCar), CP 676, 13565-905 S˜ ao Carlos, SP, Brazil 2 Instituto de Qu´ ımica de S˜ ao Carlos, Universidade de S˜ ao Paulo (USP), Colloidal Materials Group, CP 780, 13566-590 S˜ ao Carlos, SP, Brazil 3 Instituto Federal de Santa Catarina (IFSC), 89111-009 Gaspar, SC, Brazil Correspondence should be addressed to Laudemir Carlos Varanda; lvaranda@iqsc.usp.br Received 15 February 2017; Revised 1 May 2017; Accepted 14 May 2017; Published 11 June 2017 Academic Editor: Miguel A. Garcia Copyright © 2017 Caio Guilherme Secco de Souza et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We report the synthesis of a new multifunctional nanomaterial based on silica-coated FePt/Fe 3 O 4 -CdSe heteronanostructures, combining luminescent and magnetic properties in a promising bifunctional sensor for biomedical applications. Spherical Fe 3 O 4 - coated FePt (FePt/Fe 3 O 4 ) superparamagnetic nanoparticles (10.8 ± 1.5 nm) with high saturation magnetization and controlled size and shape were obtained using thermal decomposition coupled with seed-mediated growth method. Luminescent property was added to the nanomaterial by using the FePt/Fe 3 O 4 magnetic core as seed and growing the CdSe quantum dots (2.7 ± 0.6nm) onto its surface in a heterodimer-like structure using the hot-injection approach. he FePt/Fe 3 O 4 -CdSe luminomagnetic heteronanostructures were coated with silica shell using the reverse-micelle microemulsion route to avoid solvent-quenching efects. Ater silica coating, the water-dispersible heteronanostructures showed a diameter of 25.3 ± 2 nm, high colloidal stability, magnetic saturation of around 11 emu g −1 , and photoluminescence in the blue-green region, as expected for potential bifunctional platform in biomedical applications. he saturation magnetization of heteronanostructures can be increased to 28 emu g −1 by annealing at 550 ∘ C due to the presence of the FePt phase. 1. Introduction Recently, multifunctional nanomaterials with magnetic and luminescent properties have showed excellent features in potential biomedical applications in diagnosis and therapies, or as unique theranostic platform [1–3]. Among the diferent types of luminomagnetic nanomaterials, the heteronanos- tructures (HNS) show convenient response in biomedical applications, because its features provide properties related to two or more individual nanostructures in the unique nanomaterial [4–6]. Some applications of this theranostic platform include magnetic resonance imaging (MRI) [7], confocal and luorescence imaging microscopies [4, 8] acting as contrast agents, cell separation and drug delivery [9, 10] as carriers, in both optic- and magnetohyperthermia [11, 12], in which the nanoparticles are the source of heat transfer, and photodynamic therapy by singlet oxygen generation [13]. Among various kinds of theranostic nanomaterials, those based on magnetic nanoparticles can achieve both diagnosis and therapy of cancer due to their magnetic property [14]. Hyperthermia treatment can be achieved using magnetic nanoparticles in the presence of an alternate magnetic ield and the therapy success depends on the nanoparticles size, size distribution, magnetocrystalline anisotropy, and magne- tization, among others [15]. Likewise, magnetic nanoparticles can also be used as T 2 -weigthed contrast agents for MRI imaging [14]. Although diferent magnetic nanoparticles have already been tested for both in vivo and in vitro trials, Hindawi Journal of Nanomaterials Volume 2017, Article ID 2160278, 9 pages https://doi.org/10.1155/2017/2160278