Structure of graphene oxide-phospholipid monolayers: A grazing incidence X-ray diffraction and neutron and X-ray reflectivity study

M Dolores Merchán; Nisha Pawar; Andreas Santamaria; Rosalía Sánchez-Fernández; Oleg Konovalov; Armando Maestro; M Mercedes Velázquez

doi:10.1016/j.jcis.2023.11.022

Structure of graphene oxide-phospholipid monolayers: A grazing incidence X-ray diffraction and neutron and X-ray reflectivity study

J Colloid Interface Sci. 2024 Feb:655:664-675. doi: 10.1016/j.jcis.2023.11.022. Epub 2023 Nov 10.

Authors

M Dolores Merchán¹, Nisha Pawar², Andreas Santamaria³, Rosalía Sánchez-Fernández⁴, Oleg Konovalov⁵, Armando Maestro⁶, M Mercedes Velázquez⁷

Affiliations

¹ Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, E37008 Salamanca, Spain; Grupo de Nanotecnología, Universidad de Salamanca, E37008 Salamanca, Spain; Laboratorio de Nanoelectrónica and Nanomateriales, USAL-NANOLAB, Universidad de Salamanca, E37008 Salamanca, Spain.
² Centro de Física de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, E-20018 San Sebastián, Spain.
³ Institut Max von Laue and Paul Langevin, 38042 Grenoble, France.
⁴ Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, E37008 Salamanca, Spain; Institut Max von Laue and Paul Langevin, 38042 Grenoble, France.
⁵ European Synchrotron Radiation Facility, 38000 Grenoble, France.
⁶ Centro de Física de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, E-20018 San Sebastián, Spain; IKERBASQUE-Basque Foundation for Science, 48009 Bilbao, Spain. Electronic address: armando.maestro@ehu.eus.
⁷ Departamento de Química Física, Facultad de Ciencias Químicas, Universidad de Salamanca, E37008 Salamanca, Spain; Grupo de Nanotecnología, Universidad de Salamanca, E37008 Salamanca, Spain; Laboratorio de Nanoelectrónica and Nanomateriales, USAL-NANOLAB, Universidad de Salamanca, E37008 Salamanca, Spain. Electronic address: mvsal@usal.es.

PMID: 37972452
DOI: 10.1016/j.jcis.2023.11.022

Abstract

Hypothesis: Graphene oxide-based nanotechnology has aroused a great interest due to its applications in the biomedical and optoelectronic fields. The wide use of these materials makes it necessary to study its potential toxicity associated with the inhalation of Graphene Oxide (GO) nanoparticles and its interaction with the lung surfactant. Langmuir monolayers have proven to be an excellent tool for studying the properties of the lung surfactant and the effect of intercalation of nanoparticles on its structure and properties. Therefore, to know the origin of the phospholipids/GO interaction and the structure of the lipid layer with GO, in this work we study the effect of the insertion of GO sheets on a Langmuir film of 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC).

Experiments: Surface pressure-area isotherms, Neutron (NR) and X-ray Reflectivity (XRR) and Grazing Incidence X-ray Diffraction (GIXD) measurements of hydrogenated and deuterated DPPC monolayers with and without GO have been carried out.

Findings: The results outline a strong interaction between the GO and the zwitterionic form of DPPC and prove that GO is in three regions of the DPPC monolayer, the aliphatic chains of DPPC, the head groups and water in the subphase. Comparison between results obtained with hydrogenated and deuterated DPPC allows concluding that both, electrostatic attractions, and dispersion forces are responsible of the interaction GO/DPPC. Results also demonstrated that the insertion of GO into the DPPC aliphatic chains does not induce significant changes on unit cell of DPPC.

Keywords: Air-water interface; Dipalmitoyl-sn-glycerol-3-phosphocholine; Graphene oxide; Grazing incident X-ray diffraction; Neutron reflectometry; X-Ray reflectometry.