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Open access

Maciej Pilarek

Abstract

Fully synthetic, biochemically inert and water-immiscible liquid perfluorochemicals (PFCs) are recognised as flexible liquid carriers/scavengers of gaseous compounds (respiratory gases mainly, i.e. O2 and CO2) and increasingly applied in bioprocess engineering. A range of unmatched physicochemical properties of liquid PFCs, i.e. outstanding chemo- and thermostability, extremely low surface tension, simultaneous hydro- and lipophobicity, which result from carbon chain substitution with fluorine atoms (the most electronegative chemical element) and the presence of intramolecular C-F bonds (the strongest single bond known in organic chemistry) have been described in detail. Exceptional propensity to solubility of respiratory gases in liquid perfluorinated compounds has been widely discussed. Advantages and disadvantages of bioprocess applications of liquid PFCs in the form of a pure PFC as well as in an emulsified form have been pointed out. A liquid PFC-mediated mass transfer intensification in various types of microbial, plant cell and animal cell culture systems: from miniaturised microlitre-scale cultures, via biomaterial-based scaffolds containing culture systems, to litre-scale bioreactors, has been reviewed and elaborated on bearing in mind the benefits of bioprocesses.

Open access

Maciej Pilarek and Katarzyna Dąbkowska

Abstract

A mathematical model of a hybrid culture system supported with a stationary layer of liquid perfluorochemical (PFC) as a source of O2 for cells which grow in the aqueous phase of culture medium has been developed and discussed. The two-substrate Monod kinetics without inhibition effects, i.e. the Tsao-Hanson equation, has been assumed to characterise the biomass growth. The Damköhler number which relates the growth rate to the mass transfer effects has been used to appraise the regime (i.e. diffusion-limited or kinetics) of the whole process. The proposed model predicted accurately previously published data on the submerged batch cultures of Nicotiana tabacum BY-2 heterotrophic cells performed in a culture system supported with a stationary layer of hydrophobic perfluorodecalin as a liquid O2 carrier. Estimated values of the parameters of the model showed that the process proceeded in the kinetics regime and the growth kinetics, not the effects of the mass transfer between aqueous phase and liquid PFC, had essential influence on the growth of biomass.

Open access

Maciej Pilarek, Klaudia Godlewska, Aleksandra Kuźmińska, Michał Wojasiński and Katarzyna Dąbkowska

Abstract

One of the actual challenges in tissue engineering applications is to efficiently produce as high of number of cells as it is only possible, in the shortest time. In static cultures, the production of animal cell biomass in integrated forms (i.e. aggregates, inoculated scaffolds) is limited due to inefficient diffusion of culture medium components observed in such non-mixed culture systems, especially in the case of cell-inoculated fiber-based dense 3D scaffolds, inside which the intensification of mass transfer is particularly important. The applicability of a prototyped, small-scale, continuously wave-induced agitated system for intensification of anchorage-dependent CP5 chondrocytes proliferation outside and inside three-dimensional poly(lactic acid) (PLA) scaffolds has been discussed. Fibrous PLA-based constructs have been inoculated with CP5 cells and then maintained in two independent incubation systems: (i) non-agitated conditions and (ii) culture with wave-induced agitation. Significantly higher values of the volumetric glucose consumption rate have been noted for the system with the wave-induced agitation. The advantage of the presented wave-induced agitation culture system has been confirmed by lower activity of lactate dehydrogenase (LDH) released from the cells in the samples of culture medium harvested from the agitated cultures, in contrast to rather high values of LDH activity measured for static conditions. Results of the proceeded experiments and their analysis clearly exhibited the feasibility of the culture system supported with continuously wave-induced agitation for robust proliferation of the CP5 chondrocytes on PLA-based structures. Aside from the practicability of the prototyped system, we believe that it could also be applied as a standard method offering advantages for all types of the daily routine laboratory-scale animal cell cultures utilizing various fiber-based biomaterials, with the use of only regular laboratory devices.

Open access

Paweł Sobieszuk and Maciej Pilarek

The aim of this study was to determine the solubility of CO2 in perfluorodecalin (PFD) which is frequently used as efficient liquid carrier of respiratory gases in bioprocess engineering. The application of perfluorinated liquid in a microsystem has been presented. Gas-liquid mass transfer during Taylor (slug) flow in a microchannel of circular cross section 0.4 mm in diameter has been investigated. A physicochemical system of the absorption of CO2 from the CO2/N2 mixture in perfluorodecalin has been applied. The Henry’s law constants have been found according to two theoretical approaches: physical (H = 1.22·10-3 mol/m3Pa) or chemical (H = 1.26·10-3 mol/m3Pa) absorption. We are hypothesising that the gas-liquid microchannel system is applicable to determine the solubility of respiratory gases in perfluorinated liquids.

Open access

Katarzyna Dąbkowska, Maciej Pilarek and Krzysztof W. Szewczyk

Kinetic resolution of (R)- and (S)-mandelic acid by its transesterification with vinyl acetate catalysed by Burholderia cepacia lipase has been studied. The influence of the initial substrate concentration on the kinetics of process has been investigated. A modified ping-pong bi-bi model of enzymatic transesterification of (S)-mandelic acid including substrate inhibition has been developed. The values of kinetic parameters of the model have been estimated. We have shown that the inhibition effect revealed over a certain threshold limit value of the initial concentration of substrate.

Open access

Michal Wojasiński, Maciej Pilarek and Tomasz Ciach

Abstract

Comparative statistical analysis of the infiuence of processing parameters, for electrospinning (ES) and solution blow spinning (SBS) processes, on nanofibrous poly(L-lactic acid) (PLLA) material morphology and average fiber diameter was conducted in order to identify the key processing parameter for tailoring the product properties. Further, a comparative preliminary biocompatibility evaluation was performed. Based on Design of Experiment (DOE) principles, analysis of standard effects of voltage, air pressure, solution feed rate and concentration, on nanofibers average diameter was performed with the Pareto’s charts and the best fitted surface charts. Nanofibers were analyzed by scanning electron microscopy (SEM). The preliminary biocompatibility comparative tests were performed based on SEM microphotographs of CP5 cells cultured on materials derived from ES and SBS. Polymer solution concentration was identified as the key parameter infiuencing morphology and dimensions of nanofibrous mat produced from both techniques. In both cases, when polymer concentration increases the average fiber diameter increase. The preliminary biocompatibility test suggests that nanofibers produced by ES as well as SBS are suitable as the biomedical engineering scaffold material.

Open access

Katarzyna Dąbkowska, Monika Mech, Kamil Kopeć and Maciej Pilarek

Abstract

Enzymatic hydrolysis is the essential step in the production of 2nd generation biofuels made from lignocellulosic biomass, i.e. agricultural or forestry solid wastes. The enzyme-catalysed robust degradation of cellulose and hemicellulose to monosaccharides requires the synergistic action of the independent types of highly-specific enzymes, usually offered as ready-to-use preparations. The basic aim of the study was to experimentally determine the enzymatic activity of two widely industrially-applied, commercially available cellulolytic enzyme preparations: (i) Cellic® CTec2 and (ii) the mixture of Celluclast® 1.5L and Novozyme 188, in the hydrolysis of pre-treated lignocellulosic biomass, i.e. (a) energetic willow and (b) rye straw, or untreated (c) cellulose paper as well, used as feedstocks. Before the hydrolysis, every kind of utilized lignocellulosic biomass was subjected to alkaline-based (10% NaOH) pre-treatment at high-temperature (121°C) and overpressure (0.1 MPa) conditions. The influence of the type of applied enzymes, as well as their concentration, on the effectiveness of hydrolysis was quantitatively evaluated, and finally the enzyme activities were determined for each of tested cellulolytic enzyme preparations.