18. 7. 2019  2:29 Kamila
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prof. Ing. Milan Polakovič, CSc.
Identifikačné číslo: 3882
Univerzitný e-mail: milan.polakovic [at] stuba.sk
 
Profesor DrSc. - Ústav chemického a environmentálneho inžinierstva (FCHPT)
Prodekan - Fakulta chemickej a potravinárskej technológie

Kontakty     Výučba     Projekty     Publikácie     Orgány     Vedené práce     

Základné informácie

Základné informácie o záverečnej práci

Typ práce: Dizertačná práca
Názov práce:Retenčné mechanizmy častíc v sterilných mikrofiltračných membránách
Autor: Ing. Alexander Helling, PhD.
Pracovisko: Ústav chemického a environmentálneho inžinierstva (FCHPT)
Vedúci práce: prof. Ing. Milan Polakovič, CSc.
Oponent 1:doc. Ing. Vladimír Štefuca, CSc.
Oponent 2:prof. Ing. Petr Mikulášek, CSc.
Stav záverečnej práce:Záverečná práca bola úspešne obhájená


Doplňujúce informácie

Nasledujú doplňujúce informácie záverečnej práce. Kliknutím na odkaz s názvom jazyka vyberiete, v akom jazyku majú byť informácie zobrazené.

Jazyk spracovania záverečnej práce:anglický jazyk

slovenský jazyk        anglický jazyk

Názov práce:Retention mechanisms of particles in sterile filtration membranes
Abstrakt:The contaminant-free manufacture of biopharmaceutical products such as antibodies, vaccines or active pharmaceutical ingredients is a prerequisite for patient safety. Besides this, a contamination during production can lead to a substantial financial loss or even drug shortage. Contamination sources can be the media ingredients needed for cultivation, buffers, cell lines and the operators themselves. These contaminants can be bacteriophages, viruses, mycoplasma and common bacteria. For liquid process streams, membrane filtration in dead-end operation is established as the most economic and gentle method for size-based clearance of biological particle contaminations. Sieving is seen as the pre-dominant mechanism for particle retention by filter membranes, which is true for viruses and bacteria equally. However, the retention of particles can be affected by numerous other parameters in a filtration process. This work elucidates the impact of relevant process parameters on particle retention by filter membranes. These parameters include transmembrane pressure, filtration temperature, alterations in flow rate, membrane pore size, surface properties of the membranes and the temperature and ingredients of the liquid medium that has to be filtered. This work includes the manufacture, modification and characterization of membranes that have different particle retention levels with pore sizes in a broad range of 0.02 to 1.5 µm. Furthermore, relevant biological particles resembling common contaminants of an industrial bioprocess were selected and characterized mainly by their particle size, morphology and mechanical properties. These particles covered relevant microbial species in a broad size range of 0.02 to 2 µm. For this, mollicutes (commonly termed mycoplasma), common Gram-negative and Gram-positive bacteria and bacteriophages were chosen. The species significantly differ in the constitution of their cell envelope and thus impose different requirements on the membranes and process parameters to ensure a robust retention by size-based filtration. For the chosen bacteria and mycoplasma in particular robust cultivation methods were established to obtain microbial cells of reproducible quality for membrane challenging experiments. Two different unified methods were established to measure and compare the mechanical properties, i.e. the deformability, of the biological particles. These were atomic force microscopy and the compressibility of a filter cake of the particles, both leading to very comparable results. The mechanical behavior and the behavior of the biological particles during filtration under different process parameters is correlated to the particular structure found in those species. This work generally reveals that especially mycoplasma, surrounded by only a flexible lipid bilayer, can be challenging to sterilizing-grade filtration membranes, because they are relatively small, flexible and susceptible to the surrounding medium. The mechanistical concepts considered in this work facilitate making general recommendations how to achieve robust biological contaminant removal by size-exclusion based membranes in biopharmaceutical processes. This is not necessarily achieved only by smaller pores but also a rational choice of process parameters.
Kľúčové slová:Microfiltration, sterilizing-grade filtration, virusfiltration, mycoplasma, bacteria, retention, deformation, flow interruption, pressure release

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