Liposomes pp 369-383 | Cite as

Viscometric Analysis of DNA-Lipid Complexes

  • Sadao HirotaEmail author
  • Nejat Düzgüneş
Part of the Methods in Molecular Biology™ book series (MIMB, volume 606)


DNA-cationic lipid complexes, “lipoplexes”, are used as gene carriers for molecular biology and gene therapy applications. Colloidal properties of lipoplexes can be determined by viscometric analysis. (1) The shape parameter of lipoplexes can be one of the factors affecting transfection efficiency; (2) the volume fraction of free liposomes remaining after lipoplex formation can be used as an index of purity of the lipoplex product; (3) the shear dependence of the viscosity of a diluted lipoplex suspension can be used as a macroscopic shape factor: (4) the attraction force parameter between particles can be a colloidal stability factor. These properties should be characterized and specified for process control of lipoplex production and quality control of lipoplex products.

We describe an automated mini-capillary viscometer for a sample volume of 0.5 ml, and its application to the characterizations of lipoplexes. We show a procedure for viscosity measurements and provide a calculation using complexes of plant DNA-distearyldimethylammonium chloride (DDAC) at a charged ratio of 1:4 (−/+), in which the amount of DNA is less than 250 µg. The prolate/ellipsoidal axial ratio, a/b, was found to be 70. Determination of the shape parameter with a/b is found to be better than that with other shape parameters, e.g., α of the Sakurada equation, because fractionation of the particle size is not necessary. By the proposed method, colloidal parameters of lipoplexes and bioactive polymer complexes are characterized quantitatively.

Key words

Shape parameter Ellipsoid Liposomes Lipoplexes Viscosity Capillary viscometer Quality control in large scale production 



Longer semi-diameter of ellipsoid (cm)


Shorter semi-diameter of ellipsoid (cm)


Concentration in molality (mol/kg)


Length of capillary (cm)


Huggins coefficient


Attracting force parameter between particles


kat zero shear


Pressure difference between both ends of capillary (dyn/cm2)


Distance from axis of capillary (cm)


Radius of capillary (cm)


Reynolds number


Shear stress (dyn/cm2)


Shear stress at inner wall of capillary (dyn/cm2)


Yield stress (dyn/cm2)


Time (s)


Linear velocity (cm/s) at distance r from axis of capillary (cm/s)


Volume velocity, V/t, (ml/s)


Shape parameter of the Sakurada equation


Volume fraction, volume of particles / volume of suspension


Average volume fraction


Volume fraction of inner aqueous phase


Net volume fraction without inner aqueous phase


Volume fraction of cationic liposomes


Reduced viscosity, μred = η sp/c (L/g or L/mol)


Intrinsic viscosity, reduced viscosity at infinite dilution (L/g or L/mol)


Viscosity of sample liquid (poise)


Viscosity of solvent or suspending medium (poise)


Relative viscosity, η rel =η/η o


Specific viscosity, η sp =(η rel-1)


Non-dimensional reduced viscosity, η red = η sp/φ


Non-dimensional intrinsic viscosity, [η] = lim(φ→0)η red



We wish to thank Dr. Y. Sun at the Harbin Institute of Technology (China), for preparation of the lipoplexes and the flow time measurements of viscosity, and Mr. Y. Takaoka at Tokyo Denki University for automation of the mini-capillary viscometer.


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Copyright information

© Humana Press, a part of Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.Department of Material Science, School of EngineeringTokyo Denki UniversityTokyoJapan
  2. 2.Department of Microbiology, Arthur A. Dugoni School of DentistryUniversity of the PacificSan FranciscoUSA

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