title: Surface fractals in liposome aggregation.
abstract: In this work, the aggregation of charged liposomes induced by magnesium is investigated. Static and dynamic light scattering, Fourier-transform infrared spectroscopy, and cryotransmission electron microscopy are used as experimental techniques. In particular, multiple intracluster scattering is reduced to a negligible amount using a cross-correlation light scattering scheme. The analysis of the cluster structure, probed by means of static light scattering, reveals an evolution from surface fractals to mass fractals with increasing magnesium concentration. Cryotransmission electron microscopy micrographs of the aggregates are consistent with this interpretation. In addition, a comparative analysis of these results with those previously reported in the presence of calcium suggests that the different hydration energy between lipid vesicles when these divalent cations are present plays a fundamental role in the cluster morphology. This suggestion is also supported by infrared spectroscopy data. The kinetics of the aggregation processes is also analyzed through the time evolution of the mean diffusion coefficient of the aggregates.
authors.affiliation: Grupo de Física de Fluidos y Biocoloides, Departamento de Física Aplicada, Universidad de Granada, E-18071 Granada, Spain.
authors.forename: Sándalo
authors.initials: S
authors.lastname: Roldán-Vargas
authors.forename: Ramon
authors.initials: R
authors.lastname: Barnadas-Rodríguez
authors.forename: Manuel
authors.initials: M
authors.lastname: Quesada-Pérez
authors.forename: Joan
authors.initials: J
authors.lastname: Estelrich
authors.forename: José
authors.initials: J
authors.lastname: Callejas-Fernández
mesh_terms: D002118:Calcium / Q000494:pharmacology; D020285:Cryoelectron Microscopy; D004058:Diffusion / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D017709:Fractals; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D010718:Phosphatidylserines / Q000737:chemistry / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014867:Water / Q000737:chemistry / Q000378:metabolism
chemical_list: D008081:Liposomes; D010718:Phosphatidylserines; D014867:Water; D008274:Magnesium; D002118:Calcium