INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
AFM-FS insights into methyl-B-cyclodextrin effects on a phase-segregated membrane model
Autor/es:
DAZA MILLONE, M. A.; VELA, M. E.; VAZQUEZ, ROMINA; MATE, SABINA
Lugar:
Linz
Reunión:
Workshop; XXI. Annual Linz Winter Workshop; 2019
Resumen:
Cyclodextrins (CDs) are cyclic-glucose oligomers able to form water-soluble inclusion complexes with lipophilic compounds. Despite their wide use in food, chemical and pharmaceutical industries, several aspects of their capture mechanisms remain unknown. In particular, CD-mediated cholesterol (Cho) extraction from biological membranes has been described as a raft-based process, i.e. the presence of highly ordered microdomains influences the overall behavior.[ ] While liquid-ordered (Lo) domains are the main Cho reservoir, liquid-desordered domains (Ld) have shown to be the most favorable phase for Cho-extraction. [1, ] However, how the Cho depletion from the Lo domains takes place is still unclear.Here, we present in situ Atomic Force Microscopy (AFM) and Force spectroscopy (FS) measurements of the effect of methyl-β-cyclodextrin (MβCD) on a phase-segregated model membrane (DOPC/16:0 SM/ Cho in 2:1:1 molar ratio). Supported lipid bilayers (SLBs) were obtained by vesicle fusion on fresh cleaved mica as described in Maté et al.[ ] AFM images were taken in contact mode on a liquid cell and subsequently force volume (FV) maps were acquired at 23 ºC. Breakthrough events present in the force curves[ ] enable to plot an histogram with a binomial distribution, reflecting the segregated domains Ld (Fb = 4.79 ± 0.01 nN) and Lo (Fb = 12.32 ± 0.03 nN). When 1 mM MβCD was injected, Lo domains suffered a morphological reorganization accompanied by a broadening in the distribution of Fb values. After the injection of 3 mM MβCD, Lo microdomains disappeared and the images showed an unfeatured topography. Fb forces present a LogNormal distribution with a maximum at 4.5 ± 0.2 nN and upper values reaching 25 nN. Also, the indentation region of the approach curves were analyzed to obtain the elastic modulus of the lipid layer.[ ] With these results we concluded that both Lo and Ld phases suffer morphological and nanomechanical changes with MβCD mediated Cho extraction, in good agreement with the model proposed by molecular dynamic simulations.[2][1] López CA, de Vries AH, Marrink SJ. Sci. Rep. 2013;3:2071.[2] Sanchez SA, Gunther G, Tricerri MA, Gratton E. J. Membr. Biol. 2011;241(1):1-10.[3] Maté SM, Vázquez RF, Herlax VS, Daza Millone MA, Fanani ML, Maggio B, Vela ME, Bakás LS, BBA - Biomembranes 2014;1838:1832-1841.[4] Daza Millone MA, Vázquez RF, Maté SM, Vela ME. Colloids Surf. B Biointerfaces. 2018;172:423-429.[5] Li JK, Sullan RMA, Zou S Langmuir 2011; 27(4); 1308-1313