scholarly journals Determination of pH Effects on Phosphatidyl-Hydroxytyrosol and Phosphatidyl-Tyrosol Bilayer Behavior

2018 ◽  
Vol 1 (4) ◽  
pp. 41 ◽  
Author(s):  
Kervin Evans ◽  
David Compton ◽  
Michael Appell

A robust method was developed to investigate the liposomal behavior of novel enzymatically-synthesized hydroxytyrosol and tyrosol phospholipids. Bilayer characteristic obtained by this method, including bilayer formation stability and adsorption properties, were explored using dynamic light scattering, zeta-potential measurements, and quartz crystal microbalance with dissipation monitoring (QCMD), respectively. Liposome diameters were found to typically increase from pH 5.5 to pH 10. Zeta potentials values, on the other hand, were found to be well below −25 mV at all pH conditions explored, with the lowest values (and thus, the best liposome stability) at pH 5.5 or pH 10. Quartz crystal microbalance with dissipation monitoring measurements demonstrated that 100% 1,2-dioloeoylphosphatidyl-hydroxytyrosol (DOPHT) liposomes adsorbed intact onto silica in buffer conditions at pH 5.5 and with no calcium, or at pH 7.5 with calcium (no adsorption was detected at pH 10). 1,2-Dioleoylphosphatidyl-tyrosol (DOPT) liposomes were shown to adsorb intact under buffer conditions only at pH 5.5 with and without calcium. 1,2-Dioleoylphosphatidyl-2-phenolethanol (DOPPE), in comparison, readily adsorbed intact at pH 7.5 without calcium and just slightly at pH 5.5 with calcium present, but formed a supported bilayer over hours at pH 5.5 in the absence of calcium ions.

2007 ◽  
Vol 91 (11) ◽  
pp. 113507 ◽  
Author(s):  
Ihor Kulchytskyy ◽  
Martin G. Kocanda ◽  
Tao Xu

2007 ◽  
Vol 599 (2) ◽  
pp. 275-287 ◽  
Author(s):  
Abdunasser M. Etorki ◽  
A. Robert Hillman ◽  
Karl S. Ryder ◽  
Andrew Glidle

2011 ◽  
Vol 8 (60) ◽  
pp. 988-997 ◽  
Author(s):  
Julien Fatisson ◽  
Sania Mansouri ◽  
Daniel Yacoub ◽  
Yahye Merhi ◽  
Maryam Tabrizian

Platelet adhesion and activation rates are frequently used to assess the thrombogenicity of biomaterials, which is a crucial step for the development of blood-contacting devices. Until now, electron and confocal microscopes have been used to investigate platelet activation but they failed to characterize this activation quantitatively and in real time. In order to overcome these limitations, quartz crystal microbalance with dissipation (QCM-D) was employed and an explicit time scale introduced in the dissipation versus frequency plots ( Df–t ) provided us with quantitative data at different stages of platelet activation. The QCM-D chips were coated with thrombogenic and non-thrombogenic model proteins to develop the methodology, further extended to investigate polymer thrombogenicity. Electron microscopy and immunofluorescence labelling were used to validate the QCM-D data and confirmed the relevance of Df–t plots to discriminate the activation rate among protein-modified surfaces. The responses showed the predominant role of surface hydrophobicity and roughness towards platelet activation and thereby towards polymer thrombogenicity. Modelling experimental data obtained with QCM-D with a Matlab code allowed us to define the rate at which mass change occurs ( A / B ), to obtain an A / B value for each polymer and correlate this value with polymer thrombogenicity.


1996 ◽  
Vol 319 (1-2) ◽  
pp. 97-101 ◽  
Author(s):  
Lili Bao ◽  
Le Deng ◽  
Lihua Nie ◽  
Shouzhuo Yao ◽  
Wanzhi Wei

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