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Author
Title Increasing the Processability of Pullulan for Biological Applications by Changes in Molecular Weight
URL
Publication Date
Date Available
Degree MASc
Degree Level masters
University/Publisher McMaster University
Abstract

Previous studies have shown that pullulan films are able to stabilize enzymes and other labile molecules from thermal and oxidative degradation. Solutions made with commercially available pullulan are extremely viscous and difficult to process limiting the ability to use low-cost printing systems, such as inkjet printers, to format pullulan-containing. In this work, we show that pullulan can be made printable by decreasing its chain length by acid hydrolysis. The acid hydrolysis reaction was modelled using statistical software; the molecular weight of pullulan decreased with increasing reaction time, temperature and acid concentration. Interactions between time and temperature, and temperature and acid concentration were determined to be significant to the reaction as well. The mechanical properties and oxygen permeability of films made from pullulan with different molecular weights were also measured. The films were found to have similar tensile properties and oxygen permeabilities to each other and to those obtained using native pullulan. Using a thermally unstable enzyme (acetylcholinesterase) and an easily oxidizable small molecule (indoxyl acetate) as test materials, it was found that these films have the same ability to stabilize the enzyme and to serve as an oxygen barrier, as the films made with native pullulan. It was also found that pullulan is inkjet printable as long as the molecular weight is 56 kDa. Poor jetting and clogging of the printhead was observed when pullulan with a molecular weight higher than this threshold was used. Microarray printing was also demonstrated by a printing acetylcholinesterase/pullulan in nano-sized volumes using a Dimatix inkjet printer and showing activity of the enzyme after printing and storage at ambient conditions. Proof of concept of microarray printing opens up the potential for future applications of pullulan in other high throughput applications.

Thesis

Master of Applied Science (MASc)

Subjects/Keywords pullulan; acid hydrolysis; enzyme stabilization; pullulan degradation; inkjet printing
Contributors Filipe, Carlos; Chemical Engineering
Language en
Country of Publication ca
Record ID handle:11375/20538
Repository mcmaster
Date Indexed 2019-01-09

Sample Search Hits | Sample Images

…3.2 Pullulan Fragment Characterization ......................................................................... 34 3.2.1 Mechanical testing ........................................................................................... 35 3.2.2 Oxygen…

…60 vii List of Figures and Tables Figure 2.2.1. Tensile testing specimen template ............................................................. 22 Figure 2.3.1. Template of the arrangement of the AchE/pullulan mixture printed onto Whatman No. 1…

…paper from a Dimatix printer ........................................... 25 Figure 3.1.1 Molecular weight of pullulan fragments with respect to time, temperature and acid concentration from the DOE of pullulan acid hydrolysis ............ 29 Figure…

…3.1.2 Estimated coefficients of factors and interactions of a pullulan acid hydrolysis model, determined by R, using a DOE .................................... 32 Figure 3.2.1 Modulus, maximum tensile strength and percentage elongation of various…

…molecular weight pullulan films. .............................................................. 37 Figure 3.2.2 A comparison of the changing oxygen concentration over one hour for pullulan films of various molecular weights…

…40 Figure 3.2.3 Permeability of pullulan films of various molecular weights to gaseous oxygen ........................................................................................................ 41 Figure 3.2.4. The number of nozzles that eject…

…10 wt% pullulan with respect to the pullulan molecular weight compared to the viscosity of the solution; Inset: pictures from DropWatcher showing images of droplet formation or no formation for (a) a “jetting” set of nozzles, a “pulsing” set…

…3.3.2. (a) Residual activity of AchE dried in pullulan pills, stored at room temperature over 4 months; (b) Residual enzymatic activity of AchE encapsulated in pullulan of various molecular weights after 1 week and after 4 months…

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