Recombinant therapeutic proteins are an advanced way of treating various life-threatening conditions and thus becoming an important branch of modern pharmacy. Compared to conventional drugs, the building blocks of biopharmaceuticals are quite different. Biological drugs have a complex 3D structure with high molecular weight. When they are exposed to different stress conditions, protein molecules may adhere to larger clusters of similar size (aggregates). In order to ensure quality, increasing emphasis is placed on monitoring the properties and stability of proteins together with interactions between them. One of the fundamental properties of protein solutions is their viscosity. Measurement of viscosity in the early stages of drug development is also becoming increasingly interesting for progressively accurate prediction of the macroscopic impact of final product reversible self-association. Knowing the exact viscosity values of different formulations contributes to understanding and improving mathematical models of the aggregation process. The thesis describes a successful implementation of an analytical method for determining the viscosity on a VROC Initium device. It is an automatic viscometer based on the use of a microchannel and adapted to microtiter plates or vials. Measurements are fast, very accurate and consume small amounts of liquid material. Viscometer VROC enabled many experiments that were not possible before or simply not to such an extent. The saving of protein material is shown in the case of examining suitable viscosity reducing additives (VRA). Reduced sample volume needed for measurement enabled the use of smaller plastic containers. The suitability of their membranes for filtration and dialysis was scientifically confirmed. Furthermore, a new analytical method was used to confirm the correlations between the viscosity of high-concentration protein solutions and the interactions between proteins measured at low concentrations. The results of viscosity measurements of three different proteins correlate accordingly with the measurements of the dynamic interaction parameter (kD). Artificially generated larger aggregates haven't clogged the microchannel. The method successfully replaced the previously used rheometry.
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