Aggregation features of partially unfolded bovine serum albumin modulated by hydrogenated and fluorinated surfactants: Molecular dynamics insights and experimental approaches G. Scanavachi a , Y.R. Espinosa b , J.S. Yoneda a , R. Rial c , J.M. Ruso c , R. Itri a,⇑ a Instituto de Física da Universidade de São Paulo, IF USP, 05508-090 São Paulo, Brazil b Grupo de Bioquímica Teórica, Universidad Industrial de Santander, Cra 27, Calle 9, Bucaramanga, Colombia c Soft Matter and Molecular Biophysics Group, Department of Applied Physics, University of Santiago de Compostela, Santiago de Compostela, Spain graphical abstract article info Article history: Received 30 December 2019 Revised 14 March 2020 Accepted 16 March 2020 Available online 17 March 2020 Keywords: Protein aggregation Serum albumin Surfactants Sodium perfluorooctanoate (SPFO) Sodium dodecyl sulfate (SDS) SAXS MD simulation ITC abstract Protein aggregation plays important roles in life science as, for instance, those associated to neurodegen- erative diseases. Although extensive efforts have been done to elucidate all the possible variables related to the aggregation process, much has yet to be done to unveil the main pathways governing protein assembling. In the current work, we induce bovine serum albumin (BSA) association, at pH 3.7, by adding sodium dodecyl sulfate (SDS) and sodium perfluorooctanoate (SPFO) surfactants to BSA solution as pro- moters of protein aggregation. Firstly, we combine molecular dynamic simulations (MD) to obtain a par- tially unfolded state of BSA’s monomer at the acid pH and small angle X-ray scattering (SAXS) to validate the model. Interestingly, we found by SAXS that at pH 3.7 BSA monomers coexist with dimers in surfactant-free solution. Upon SDS and SPFO addition, the partial unfolded BSA may evolve to large aggre- gates depending on surfactant concentration. The threshold occurs at 30:1 and 45:1 SDS:BSA and SPFO: BSA molar ratio, respectively, according to turbidity, Thioflavin (ThT) fluorescence, synchrotron radiation circular dichroism (SRCD), SAXS and scanning electron microscopy (SEM) experiments. BSA aggregates are larger in the presence of SDS and structurally more defined upon SPFO binding. Isothermal titration calorimetry (ITC) results give support to infer that both surfactants initially bind to the BSA macro- molecule forming a complex. Then, these complexes self-associate towards supramolecular aggregates. Taking into account the physicochemical characteristics of both surfactants and also MD simulations we may suggest that the higher rigidity of the fluorinated chains in respect to hydrogenated ones is cru- cial to induce more ordered and smaller BSA’s aggregates. Our results thus evidence that the ligand https://doi.org/10.1016/j.jcis.2020.03.059 0021-9797/Ó 2020 Elsevier Inc. All rights reserved. ⇑ Corresponding author. E-mail address: itri@if.usp.br (R. Itri). Journal of Colloid and Interface Science 572 (2020) 9–21 Contents lists available at ScienceDirect Journal of Colloid and Interface Science journal homepage: www.elsevier.com/locate/jcis