Direct Measurement of Charge Reversal on Lipid Bilayers using Heterodyne-Detected Second Harmonic Generation Spectroscopy

Author(s):  
HanByul Chang ◽  
Paul Ohno ◽  
Yangdongling Liu ◽  
Franz Geiger

We report the detection of charge reversal induced by the adsorption of a cationic polyelectrolyte, poly(allylamine) hydrochloride (PAH), to buried supported lipid bilayers (SLBs), used as idealized model biological membranes. We observe changes in the surface potential in isolation from other contributors to the total SHG response by extracting the phase-shifted potential-dependent third-order susceptibility from the overall SHG signal. We demonstrate the utility of this technique in detecting both the sign of the surface potential and the point of charge reversal at buried interfaces without any prior information or complementary techniques<i>.</i>Furthermore, isolation of the second-order susceptibility contribution from the overall SHG response allows us to directly monitor changes in the Stern Layer. Finally, we characterize the Stern and Diffuse Layers over single-component SLBs formed from three different zwitterionic lipids of different gel-to-fluid phase transition temperatures (T<sub>m</sub>s). We determine whether the surface potential changes with the physical phase state (gel, transitioning, or fluid) of the SLB and incorporate 20 percent of negatively charged lipids to the zwitterionic SLB to investigate how the surface potential changes with surface charge.

2019 ◽  
Author(s):  
HanByul Chang ◽  
Paul Ohno ◽  
Yangdongling Liu ◽  
Emilie Lozier ◽  
Naomi Dalchand ◽  
...  

<div><div><div><p>We report the detection of charge reversal induced by the adsorption of a cationic polyelectrolyte, poly(allylamine) hydrochloride (PAH), to buried supported lipid bilayers (SLBs), used as idealized model biological membranes. Through the use of an α-quartz reference crystal, we quantify the total interfacial potential at the interface in absolute units, using HD-SHG as an optical voltmeter in which the traditional wire leads of a voltmeter have been replaced by photons. This quantification is made possible by isolating from other contributions to the total SHG response the phase-shifted potential-dependent third-order susceptibility. We detect the sign and magnitude of the surface potential and the point of charge reversal at buried interfaces without prior information or complementary data. Isolation of the second-order susceptibility contribution from the overall SHG response allows us to directly characterize the Stern and Diffuse Layers over single-component SLBs formed from three different zwitterionic lipids of different gel-to-fluid phase transition temperatures (Tms). We determine whether the surface potential changes with the physical phase state (gel, transitioning, or fluid) of the SLB and incorporate 20 percent of negatively charged lipids to the zwitterionic SLB to investigate how the surface potential and the</p><p>second-order nonlinear susceptibility chi(2) change with surface charge.</p></div></div></div>


2019 ◽  
Author(s):  
HanByul Chang ◽  
Paul Ohno ◽  
Yangdongling Liu ◽  
Emilie Lozier ◽  
Naomi Dalchand ◽  
...  

<div><div><div><p>We report the detection of charge reversal induced by the adsorption of a cationic polyelectrolyte, poly(allylamine) hydrochloride (PAH), to buried supported lipid bilayers (SLBs), used as idealized model biological membranes. Through the use of an α-quartz reference crystal, we quantify the total interfacial potential at the interface in absolute units, using HD-SHG as an optical voltmeter in which the traditional wire leads of a voltmeter have been replaced by photons. This quantification is made possible by isolating from other contributions to the total SHG response the phase-shifted potential-dependent third-order susceptibility. We detect the sign and magnitude of the surface potential and the point of charge reversal at buried interfaces without prior information or complementary data. Isolation of the second-order susceptibility contribution from the overall SHG response allows us to directly characterize the Stern and Diffuse Layers over single-component SLBs formed from three different zwitterionic lipids of different gel-to-fluid phase transition temperatures (Tms). We determine whether the surface potential changes with the physical phase state (gel, transitioning, or fluid) of the SLB and incorporate 20 percent of negatively charged lipids to the zwitterionic SLB to investigate how the surface potential and the</p><p>second-order nonlinear susceptibility chi(2) change with surface charge.</p></div></div></div>


2010 ◽  
Vol 105 (7/8) ◽  
Author(s):  
P.H. Neethling ◽  
T. T. Scheidt ◽  
E.G. Rohwer ◽  
H.M. Von Bergmann ◽  
H. Stafast

2011 ◽  
Vol 100 (3) ◽  
pp. 505a
Author(s):  
Matteo Broccio ◽  
Paul J. Sides ◽  
Mathias Lösche

2007 ◽  
Vol 40 (5) ◽  
pp. 919-923
Author(s):  
J. Etxebarria ◽  
J. Ortega ◽  
C. L. Folcia

Measurements of the optical rotation of LiB3O5have been carried out using a high-accuracy universal polarimeter in the temperature range 298–503 K. The results have been analyzed within the framework of a point-dipole model for the optical rotation. Though the magnitude of the rotation is very small, its sign has been clearly determined and linked to the crystallographic structure. A slight modification of the point-dipole model also permits an explanation of the values of the second-order susceptibility coefficients for second-harmonic generation.


1987 ◽  
Vol 109 ◽  
Author(s):  
John C. Luong ◽  
N. F. Borrelli ◽  
A. R. Olszeuski

ABSTRACTA convenient method of measuring the nonlinear optical properties of molecular compounds is described. The method involves measuring the quadratic electro-optical coefficient of a polymer composite containing a variable concentration of the candidate NLO material. The X(3) (ω) value obtained by this low-frequency Kerr measurement, after local-field corrections, can be compared to the nonresonant third-order susceptibility measured by degenerate-four-wave-mixing technique on selective samples. We find that the choice of the polymer matrix dictates the contribution of second-order susceptibility to the Kerr coefficient. Therefore, our method can also be extended to the measurement of second-order susceptibility, analogous to the technique of field-induced second-harmonic-generation.


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