title: 2D dynamical arrest transition in a mixed nanoparticle-phospholipid layer studied in real and momentum spaces.
abstract: We investigate the interfacial dynamics of a 2D self-organized mixed layer made of silica nanoparticles interacting with phospholipid (DPPC) monolayers at the air/water interface. This system has biological relevance, allowing investigation of toxicological effects of nanoparticles on model membranes and lung surfactants. It might also provide bio-inspired technological solutions, exploiting the self-organization of DPPC to produce a non-trivial 2D structuration of nanoparticles. The characterization of interfacial dynamics yields information on the effects of NPs on the mechanical properties, important to improve performances of systems such as colloidosomes, foams, creams. For this, we combine micro-tracking in real-space with measurement in momentum-space via x-ray photon-correlation spectroscopy and Digital Fourier Microscopy. Using these complementary techniques, we extend the spatial range of investigation beyond the limits of each one. We find a dynamical transition from Brownian diffusion to an arrested state driven by compression, characterized by intermittent rearrangements, compatible with a repulsive glass phase. The rearrangement and relaxation of the monolayer structure results dramatically hindered by the presence of NPs, which is relevant to explain some the mechanical features observed for the dynamic surface pressure response of these systems and which can be relevant for the respiratory physiology and for future drug-delivery composite systems.
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Parma, Parma, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Orsi
authors.affiliation: Consiglio Nazionale delle Ricerche - Istituto per l'Energetica e le Interfasi, U.O.S. Genova (CNR IENI), Genova (Italy).
authors.forename: Eduardo
authors.initials: E
authors.lastname: Guzmán
authors.affiliation: Consiglio Nazionale delle Ricerche - Istituto per l'Energetica e le Interfasi, U.O.S. Genova (CNR IENI), Genova (Italy).
authors.forename: Libero
authors.initials: L
authors.lastname: Liggieri
authors.affiliation: Consiglio Nazionale delle Ricerche - Istituto per l'Energetica e le Interfasi, U.O.S. Genova (CNR IENI), Genova (Italy).
authors.forename: Francesca
authors.initials: F
authors.lastname: Ravera
authors.affiliation: ESRF- The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Ruta
authors.affiliation: ESRF- The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France.
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Chushkin
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Parma, Parma, Italy.
authors.forename: Tiziano
authors.initials: T
authors.lastname: Rimoldi
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Parma, Parma, Italy.|Consiglio Nazionale delle Ricerche - Istituto per l'Energetica e le Interfasi, U.O.S. Genova (CNR IENI), Genova (Italy).
authors.forename: Luigi
authors.initials: L
authors.lastname: Cristofolini
mesh_terms: D000388:Air; D000465:Algorithms; D008962:Models, Theoretical; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D010743:Phospholipids / Q000737:chemistry*; D011663:Pulmonary Surfactants / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D010743:Phospholipids; D011663:Pulmonary Surfactants; D014867:Water; D012822:Silicon Dioxide