Regular Article Processing and size range separation of pristine and magnetic poly(L-lactic acid) based microspheres for biomedical applications D.M. Correia a,b,⇑,1 , V. Sencadas a,c,1 , C. Ribeiro a,d,⇑ , P.M. Martins a , P. Martins a , F.M. Gama d , G. Botelho b , S. Lanceros-Méndez a,e,f a Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal b Centro/Departamento de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal c School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, Wollongong, NSW 2522, Australia d CEB – Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal e BCMaterials, Parque Científico y Tecnológico de Bizkaia, 48160 Derio, Spain f IKERBASQUE, Basque Foundation for Science, Bilbao, Spain graphical abstract article info Article history: Received 18 March 2016 Revised 5 May 2016 Accepted 11 May 2016 Available online 11 May 2016 Keywords: Biocompatibility Poly(L-lactic acid) microspheres Oil in water emulsion technique Cell viability Magnetic nanocomposites abstract Biodegradable poly(L-lactic acid) (PLLA) and PLLA/CoFe 2 O 4 magnetic microspheres with average sizes ranging between 0.16–3.9 lm and 0.8–2.2 lm, respectively, were obtained by an oil-in-water emulsion method using poly(vinyl alcohol) (PVA) solution as the emulsifier agent. The separation of the micro- spheres in different size ranges was then performed by centrifugation and the colloidal stability assessed at different pH values. Neat PLLA spheres are more stable in alkaline environments when compared to magnetic microspheres, both types being stable for pHs higher than 4, resulting in a colloidal suspension. On the other hand, in acidic environments the microspheres tend to form aggregates. The neat PLLA micro- spheres show a degree of crystallinity of 40% whereas the composite ones are nearly amorphous (17%). Finally, the biocompatibility was assessed by cell viability studies with MC3T3-E1 pre-osteoblast cells. Ó 2016 Elsevier Inc. All rights reserved. 1. Introduction Smart polymer microspheres have received increasing attention for biomedical applications such as drug delivery systems and support for cell expansion and differentiation [1,2]. http://dx.doi.org/10.1016/j.jcis.2016.05.012 0021-9797/Ó 2016 Elsevier Inc. All rights reserved. ⇑ Corresponding authors at: Centro/Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal. E-mail address: cribeiro@fisica.uminho.pt (C. Ribeiro). 1 Equal contribution. Journal of Colloid and Interface Science 476 (2016) 79–86 Contents lists available at ScienceDirect Journal of Colloid and Interface Science journal homepage: www.elsevier.com/locate/jcis