6 BIOTECHNOLOGY


Fig. 1. New mobility instruments achieve these goals through massive parallelism of detection.


Measuring electrophoretic mobility of macromolecules


The measurement of mobilities of large particles, such as liposomes and virus-like particles, has historically been challenging. Vincent Hsieh reports on instrumentation developed specifically to address this problem.


La mesure des mobilités des particules larges, telles que les liposomes et les particules s’apparentant aux virus, a depuis longtemps posé des difficultés. Vincent Hsieh a fait un rapport sur les instruments spécifiquement développés pour aborder ce problème..


Die Messung der Beweglichkeit großer Partikel wie etwa Liposome und virusähnliche Partikel ist seit jeher eine anspruchsvolle Aufgabe. Vincent Hsieh berichtet über Messinstrumente, die zur Lösung dieses Problems speziell entwickelt wurden.


E


lectrical charge is a fundamental property of all macromolecules. In colloidal suspensions, the amount of charge and screening developed at the interfaces between particles and media is of utmost importance in determining the formulation stability.


For many biomolecules such as proteins, electrostatic interactions also exercise a profound influence on their conformations and functions.


Since a direct measurement of the interfacial potential is rarely feasible, the electrophoretic mobility has become the most popular and widely accepted proxy for molecular charge.


As well as being a non-invasive www.scientistlive.com


method, laser light scattering is prized for its ability to carry out physical, first-principle measurements of macromolecules’ electrophoretic mobilities.


However, when it comes to proteins, satisfactory results have been difficult to come by due to their small sizes (<5 nm) and their more conspicuous Brownian motions.


Lengthier measurements are therefore necessary to average out the mobility-masking diffusion and reveal the macromolecular electrophoresis.


In the process, these fragile molecules are subjected to electrical currents and often irreversibly damaged


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