Tailoring of carboxyl-decorated magnetic latex particles using seeded emulsion polymerization Talha Jamshaid a , Mohamed M. Eissa a,b , Quentin Lelong a , Anne Bonhommé c , Geraldine Augsti a , Nadia Zine c , Abdelhamid Errachid c and Abdelhamid Elaissari a * In this research, submicron and carboxyl-functionalized magnetic latex particles were elaborated by using seeded emulsion polymerization technique in presence of oil-in-water (o/w) magnetic emulsion as seed. The polymerization conditions were optimized in order to get well-defined latex particles with magnetic core and polymer shell bearing carboxylic (–COOH) functionality. Starting from (o/w) magnetic emulsion as seed, synthesis process was performed by copolymerization of styrene (St) monomer with the cross-linker divinylbenzene (DVB) in presence of 4,4 0 - azobis(4-cyanopentanoic acid) (ACPA) as a carboxyl-bearing initiator. The prepared magnetic latex particles were first characterized in terms of particle size, chemical composition, morphology, magnetic properties, magnetic con- tent, and colloidal stability using various techniques, e.g. particle size analyzer using dynamic light scattering (DLS) technique, Fourier transform infrared, transmission electron microscopy, vibrating sample magnetometer, thermo- gravimetric analysis, and zeta potential measurements as a function of pH of the dispersion media, respectively. The prepared magnetic latex particles were then used as second seed for further functionalization with methacrylic acid (MAA) in order to enhance carboxylic groups on the magnetic particle’s surface. The results showed that final magnetic latex particles possessed spherical morphology with core-shell structure and enriched carboxylic acid func- tionality. More importantly, they exhibited superparamagnetism with high magnetic content (58.42 wt%) and high colloidal stability, which considered as the main requirements for their application in the biomedical diagnostic do- mains. Copyright © 2017 John Wiley & Sons, Ltd. Keywords: magnetic emulsion; seeded emulsion polymerization; core-shell morphology; functionalization; methacrylic acid INTRODUCTION In the last decade, various colloidal particles have been used as solid supports in the biomedical field. [1–6] However, the recent develop- ment in magnetic nanoparticles (Fe 3 O 4 : magnetite and γ-Fe 2 O 3 : maghemite) [7–11] has shown many advantages in various fields. The specific property of superparamagnetism [12–14] makes them dis- tinguished from other nanoparticles (e.g. gold, silver, and quantum dots) and that is why these particles found various applications in biotechnology, biomedical diagnostics, and environmental and food analyses. [2,15,16] Later on, the hybridization between magnetic nano- particles and polymers to form magnetic latex particles has attracted great attention in various fields, significantly in the biomedical do- main. [10,17–24] In addition to their superparamagnetism, magnetic la- tex particles possess some important features as compared with other particles, including large specific surface area, narrow size dis- tribution, and versatility in modification of surface functionality, which make them convenient to be widely used as good carriers for biomolecules. Moreover, the main advantage of using these par- ticles is their fast separation by applying an external magnetic field in one step to avoid the laborious and time-consuming separation processes (e.g. filtration, sedimentation, and centrifugation),which limit the automation of biomedical diagnosis. [25,26] Nowadays, magnetic latex particles are commonly used as solid supports for specific capture of the targeted biomolecules such as antigens in immunoassays and in molecular biology for specific nucleic acid detection. In this regard, many synthetic processes have been used to obtain magnetic latex particles with controllable structure, [27] including layer-by-layer assem- bly, [28] dispersion polymerization, [29] miniemulsion polymeriza- tion, [20] and adsorption or heterocoagulation process. [30] However, these processes showed some limitations, e.g. low iron oxide content, nonhomogeneous encapsulation of inorganic particles, and broad size distribution. In bionanotechnology, the characteristic elaboration of magnetic latexes is generally to protect the inorganic part from oxidation and to produce reactive chemical functions capable for immobilizing * Correspondence to: Abdelhamid Elaissari, University of Lyon, University Lyon-1, CNRS, UMR 5007, LAGEP-CPE, 43 Bd. 11 Novembre 1918, F-69622 Villeurbanne, France. E-mail: elaissari@lagep.univ-lyon1.fr a T. Jamshaid, M. M. Eissa, Q. Lelong, G. Augsti, A. Elaissari University of Lyon, University Lyon-1, CNRS, UMR 5007, LAGEP-CPE, 43 Bd. 11 Novembre 1918, F-69622, Villeurbanne, France b M. M. Eissa Polymers and Pigments Department, National Research Centre, 33 El Bohouth St. (Former El Tahrir St.), Dokki, Giza 12622, Egypt c A. Bonhommé, N. Zine, A. Errachid Institut des Sciences Analytiques, Université de Lyon, UMR 5280, CNRS, Université Lyon 1, ENS Lyon - 5, rue de la Doua, F-69100, Villeurbanne, France Research article Received: 25 September 2016, Revised: 28 November 2016, Accepted: 12 December 2016, Published online in Wiley Online Library: 5 January 2017 (wileyonlinelibrary.com) DOI: 10.1002/pat.4001 Polym. Adv. Technol. 2017, 28 1088–1096 Copyright © 2017 John Wiley & Sons, Ltd. 1088