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Polymers are of great interest for medical and cosmeceutical applications. The current trend is to combine materials of natural and synthetic origin in order to obtain products with appropriate mechanical strength and good biocompatibility, additionally biodegradable and bioresorbable. Citric acid, being an important metabolite, is an interesting substance for the synthesis of materials for biomedical applications. Due to the high functionality of the molecule, it is commonly used in biomaterials chemistry as a crosslinking agent. Among citric acid‐based biopolyesters, poly(1,8‐octanediol citrate) is the best known. It shows application potential in soft tissue engineering. This work focuses on a much less studied polyester, poly(1,3‐propanediol citrate). Porous and non‐porous materials based on the synthesized polyesters are prepared and characterized, including mechanical, thermal, and surface properties, morphology, and degradation. The main focus is on assessing the biocompatibility and antimicrobial properties of the materials. [ABSTRACT FROM AUTHOR]

Mixing time is an important parameter for quantifying the mixing efficiency of a bioreactor system, essential for successful bioprocess development in various branches of the bioengineering sector (e.g., biopharma, biorefineries, food industry and bioreactor design). The colourimetric method is one of the ways of obtaining valuable quantitative data about the mixing process and the liquid flow inside a vessel. This review consists of a catalogue and a discussion of previously published data in which the colourimetric method has been utilised; a critical comparison between the colourimetric and other mixing time measurement methods; an explanation of practical considerations regarding the bioreactor setup and the choice of reagents; a practical guide for requirements for the acquisition of high-quality images of the mixing process; a thorough discussion of aspects connected to the computer image processing of the video material. This review is intended to thoroughly present the versatility of the colourimetric method for mixing time measurement in miscellaneous bioreactor systems, i.e., in classical tanks and modern single-use (disposable) plastic film-based bag-like containers, and to facilitate the implementation of the colourimetric method in new research setups by providing complete and valuable recommendations about each step of the methodology. [ABSTRACT FROM AUTHOR]

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.

Abstract Background Liquid perfluorochemicals (PFCs) are interesting oxygen carriers in medicine and biotechnology with a high solubility for oxygen. They have been repeatedly used for improving oxygen transfer into prokaryotic and eukaryotic cell cultures, however their application is still limited. Here we show the great benefit of air/oxygen saturated perfluorodecalin (PFD) for high cell density cultivation of Escherichia coli in microwell plates and their positive effect on the soluble production of a correctly folded heterologously expressed alcohol dehydrogenase. Results In EnBase® cultivations the best effect was seen with PFD saturated with oxygen enriched air (appr. 10 μM oxygen per ml) when PFD was added at the time of induction. In contrast the effect of PFD was negligible when it was added already at the time of inoculation. Optimisation of addition time and content of loaded oxygen into the PFD resulted in an increased the cell density by 40% compared to control cultures, and correspondingly also the product yield increased, demonstrated at the example of a recombinant alcohol dehydrogenase. Conclusions PFCs are a valuable additive in miniaturized cell culture formats. For production of recombinant proteins in low cell density shaken cultures the addition of oxygen-enriched PFD makes the process more robust, i.e. a high product yield is not any more limited to a very narrow cell density window during which the induction has to be done. The positive effect of PFD was even more obvious when it was added during high cell density cultures. The effect of the PFD phase depends on the amount of oxygen which is loaded into the PFD and which thus is a matter of optimisation.

The physicochemical parameters of the liquid phase have influence significantly on the rate of oxygen absorption in liquid. Feasibility of wave-type agitated single-use bioreactors for bioprocesses involving in vitro cultures makes the study of the influence of liquid properties on values of the volumetric mass transfer coefficient (kLa) interesting and actual research issue. ReadyToProcess WAVE™25 single-use bioreactor system (WAVE 25; GE Healthcare Bio-Sciences AB, Sweden), equipped with 2 dm3 polymer-based culture bag, has been used for studying the oxygen absorption rate in the wave-induced agitation system. The influence of viscosity of liquid on the rate of oxygen absorption under wave-type agitation has been discussed. The increase of liquid phase viscosity negatively influenced on the rate of oxygen absorption, and lead to decreasing in values of the kLa coefficient in studied system. Fetal bovine serum strongly limited significantly the rate of oxygen absorption into the liquid phase, what resulted in a significant decrease in the kLa coefficient. [ABSTRACT FROM AUTHOR]

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Pre-treatment is one of the most important stages in the production of valuable bioproducts from lignocellulosic feedstock. It aims to destroy the complex structure of raw materials, what contributes to increase their susceptibility to enzymatic saccharification. For each type of used raw materials, it is necessary to verify the applicability of the selected pre-treatment method and process parameters. In the present work the effectiveness of pre-treatments carried out in 2% H2SO4 and 2% NaOH at various process conditions, for three lignocellulosic raw materials: (i) corn stover, (ii) corn cob, and (iii) fast-growing poplar wood, were compared. As a measure of the process efficiency, the overall yields of monosaccharides release from biomass were determined based on the amounts of glucose and xylose dissolved in the solutions used for pre-treatment as well as on the their amounts produced during enzymatic hydrolysis of solid fraction of biomass obtained after pre-treatment. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine surface properties of perfluorodecalin-water system supplemented with surface active polymer Pluronic F-68 which has been dissolved in the aqueous phase at 37°C. Surface tensions were measured by the du Noüy ring method for polymer concentration ranged from 0.00012 up to 0.12 mM. Analogous measurements were performed for air-water system. Surface properties, i.e. the critical micelle concentration (CMC) and the standard free energy of micellization (▵G°mic) for both studied two - phase systems were determined. Due to the fact that Pluronic F-68 is insoluble in perfluorodecalin, as well as perfluorodecalin does not dissolve in the aqueous phase, both obtained CMC values were similar. Calculated values of (▵G°mic) indicated that formation of micelles was spontaneous for polymer concentrations higher than CMC. [ABSTRACT FROM AUTHOR]

Efficient and reproducible cell lysis is a crucial step during downstream processing of intracellular products. The composition of an optimal lysis buffer should be chosen depending on the organism, its growth status, the applied detection methods, and even the target molecule. Especially for high-throughput applications, where sample volumes are limited, the adaptation of a lysis buffer to the specific campaign is an urgent need. Here, we present a general design of experiments-based strategy suitable for eight constituents and demonstrate the strength of this approach by the development of an efficient lysis buffer for Gram-negative bacteria, which is applicable in a high-throughput format in a short time. The concentrations of four lysis-inducing chemical agents EDTA, lysozyme, Triton X-100, and polymyxin B were optimized for maximal soluble protein concentration and ß-galactosidase activity in a 96-well format on a Microlab Star liquid handling platform under design of experiments methodology. The resulting lysis buffer showed the same performance as a commercially available lysis buffer. The developed protocol resulted in an optimized buffer within only three runs. The established procedure can be easily applied to adapt the lysis buffer to other strains and target molecules. [ABSTRACT FROM AUTHOR]

For a commercially viable recombinant intracellular protein production process, efficient cell lysis and protein release is a major bottleneck. The recovery of recombinant protein, oxidasecholesterol oxidase (COD) was studied in a continuous bead milling process. A full factorial response surface methodology (RSM) design was employed and compared to artificial neural networks coupled with genetic algorithm (ANN-GA). Significant process variables, cell slurry feed rate (A), bead load (B), cell load (C), and run time (D), were investigated and optimized for maximizing COD recovery. RSM predicted an optimum of feed rate of 310.73 mL/h, bead loading of 79.9% (v/v), cell loading OD600 nm of 74, and run time of 29.9 min with a recovery of ~3.2 g/L. ANN-GA predicted a maximum COD recovery of ~3.5 g/L at an optimum feed rate (mL/h): 258.08, bead loading (%, v/v): 80%, cell loading (OD600 nm): 73.99, and run time of 32 min. An overall 3.7-fold increase in productivity is obtained when compared to a batch process. Optimization and comparison of statistical vs. artificial intelligence techniques in continuous bead milling process has been attempted for the very first time in our study. We were able to successfully represent the complex non-linear multivariable dependence of enzyme recovery on bead milling parameters. The quadratic second order response functions are not flexible enough to represent such complex non-linear dependence. ANN being a summation function of multiple layers are capable to represent complex non-linear dependence of variables in this case; enzyme recovery as a function of bead milling parameters. Since GA can even optimize discontinuous functions present study cites a perfect example of using machine learning (ANN) in combination with evolutionary optimization (GA) for representing undefined biological functions which is the case for common industrial processes involving biological moieties. [ABSTRACT FROM AUTHOR]