|
|
Preparation and characterization of food and cosmetic products containing selected vitamins
Kubošová, Jana ; Pavelková, Renata (referee) ; Skoumalová, Petra (advisor)
This bachelor thesis deals with the preparation and characterization of encapsulated forms of lipophilic vitamins in model conditions, focusing on cosmetic and food applications. The theoretical part describes the individual vitamins, their physiological effects, physical and chemical properties, sources and sequels of hypo/hypervitaminoses. Furthermore, their contribution in medicine, food industry and cosmetics, methods of determination and in the last part of the encapsulation method are discussed. Special attention is dedicated to the technique of particles encapsulation using liposomes, which was used in the practical part. The experimental part is focused on the study of liposomes of selected substances of vitamin nature. Namely, the issue of cholecalciferol, tocopherol and -carotene was addressed, for which a suitable method of determination was introduced. Subsequently, encapsulation of these substances and characterization of the prepared liposomes took place. Their size, stability and encapsulation efficiency, which reached high percentages, were determined. Liposomes were further put to the stability tests in digestive juices and model medium simulating cosmetic products. During the measured time, the release of encapsulated substances into the surroundings and their gradual degradation was monitored. At the end of the work, analytes were extracted from real foods and cosmetic products and the measured concentrations were compared with the declared values.
|
|
|
Development and characterization of hydrogel carriers for modern agricultural applications
Mai, Thuy Ha ; Kalina, Michal (referee) ; Sedláček, Petr (advisor)
The bachelor thesis is focused on characterization of hydrogel carriers and their application in agriculture. Entrapment of active phase within the hydrogel matrix would allow release of its content in controlled rate. The theoretical part describes encapsulation techniques and suitable biocompatible materials involved in encapsulation. For the experimental part, the release of soil bacteria Cupriavidus necator H16 from alginate matrix was examined. The focus was on the release rate of bacteria via diffusion and later, on the release rate of bacteria encouraged by chemical or enzymatic reagents. Further modification of carrier was suggested by adding hydrophobic barrier composed of polyhydroxybutyrate (PHB). The modified alginate beads seemed to be more resistant toward enzymatic or chemical agents, thus the process of the release was to some extent suppressed. This fact might suggest PHB as a possible vessel for optimization of controlled release system of hydrogel carriers.
|
|
|
Hydrogel carriers of microorganisms for modern environmental aplications.
Súkeník, Martin ; Slaninová, Eva (referee) ; Sedláček, Petr (advisor)
This bachelor thesis deals with the optimization of cultivation and gelation procedures by bacterium Azotobacter vinelandii, which belongs to a PGPR group, capable of synthesis of intracellular polyhydroxyalkanoates and extracellular alginate. The alginate produced by the bacteria is crosslinked with a calcium chloride solution to form a hydrogel carrier containing the described bacterium. This unconventional concept simplifies bacterial encapsulation and production of hydrogel carriers, furthermore expands its usability in modern environmental applications. In the first part of this thesis, three strains (DSM 85, 87, 720) were selected to measure a concentration of produced alginate, its molecular weight was determined by a SEC-MALS technique and M/G ratio was analysed by infrared spectroscopy. The Azotobacter vinelandii strain DSM 87 reached the highest concentration of the alginate (4.9 ± 0.6) g/l by gravimetric determination on the 5th day of cultivation. The concentration of produced PHB ranges from 48 to 6 % of CDW, which was determined by gas chromatography. Nevertheless, the strain DSM 720 showed the best gelation properties and was used in the second part of this thesis for further optimization of the cultivation process, and for the analysis the formation of gelation procedure under different temperatures, gelation time and concentrations of crosslinking solution. The formed gels were compared by rheological measurements of amplitude and frequency tests.
|
|
|
Preparation and characterization of hydrogel delivery systems from poly-gamma-glutamic acid
Mai, Thuy Ha ; Smilek, Jiří (referee) ; Sedláček, Petr (advisor)
The presented diploma thesis focuses on the development and preparation of model poly--glutamic acid based hydrogel carrier systems. For the hydrogel carrier preparation, methods based on physical interactions between polyelectrolyte and oppositely charged multivalent ion or oppositely charged macromolecule were proposed. Based on the pilot experiments, trivalent iron cation and chitosan were selected as suitable crosslinking agents. By crosslinking -PGA via ferric cations a successful bead formation has been accomplished and attempts have been made for a preparation of beads smaller than 1 000 m by employing microencapsulation techniques. Rapid disintegration of -PGA beads occurred upon immersion of the beads in water making these systems unsuitable for drug carrier applications. Interactions between -PGA and chitosan lead to polyelectrolyte complexes formation and by optimizing concentrations and pH of polyelectrolyte solutions, a formation of homogenous looking hydrogel with high water content (>0,9) has been achieved.
|
|
|
Encapsulation of natural antioxidants
Štindlová, Jitka ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
In theoretical part of this diploma thesis the basic properties of antioxidants, especially anthocyanins and phenolic compounds are described, as well as the basic features and principles of free radicals formation. The theoretical part also describes some possible ways of encapsulation of antioxidants into polysaccharide and lipid particles. In the experimental part basic characteristics of extracts from selected lyophilized fruits and vegetables (carrots, apples and mixed berries) are described. As group parameters of plant extracts the total antioxidant activity, content of flavonoids and phenolics, carotenoids, anthocyanins and ascorbic acid were determined. In experimental part also various encapsulation techniques were tested, encapsulation effectiveness of each technique was evaluated and the stability and size of the created particles were determined. As the best encapsulation method in terms of encapsulation efficiency in most of samples/parameters ethanol injection was found. On the other hand the particles prepared by ethanol injection are relatively unstable in terms of zeta potential, which is followed by their tendency to aggregate. As the most stable particles prepared by thin layer evaporation (TLE) and reverse phase thin layer evaporation (RP-TLE) were evaluated. Particles prepared by TLE, RP-TLE and chitosan-alginate particles exhibited a negative charge, while particles prepared by ethanol injection stayed uncharged and chitosan particles have a positive charge.
|
|
|
Self-encapsulation of Plant Growth Promoting Rhizobacteria as a way towards new generation of bioinoculants
Gašparová, Dominika ; Obruča, Stanislav (referee) ; Sedláček, Petr (advisor)
This bachelor thesis focuses on Plant Growth-Promoting Rhizobacteria that can be used as a suitable ecological alternative to conventional fertilizers. However, most of today's approaches to incorporating PGPR into the process of soil fertilization are convoluted and costly. Crosslinking of alginate self-produced by PGPR offers a new possibility of plantgrowth- promoting bacteria encapsulation. The aim of this thesis consists of preparing gel matrices with incorporated bacteria, followed by testing the bacteria's viability and quantity. Firstly, experiments were carried out to determine various properties of gels produced by the chosen representative bacteria Azotobacter vinelandii. These properties include the molecular weight of alginate (with the highest molecular weight of strain CCM 289 (329,78± 6,8) kDa), the alginate's amount in the gel, the content of PHB (34%-44% CDW), and the gel's overall rheological properties. The complex modulus (as a representation of rheological properties) of the firmest gel reached the value of 13,34 kPa. The bacteria content was examined by flow cytometry, the CFU method, and spectrophotometry. The viability of bacteria was determined by analyzing the fluorescence intensity via fluorescent dyes (propidium iodide, fluorescein diacetate, rhodamine 123, calcein AM), then by using the CFU method, and also via the plate method. Furthermore, the effects of various factors such as different pH levels (pH 3, 7, and 10) or adding the specific alginatedegrading enzyme alginase were also examined. Releasing of the bacteria was observed over the course of seven days using flow cytometry and the CFU method. The plate method proved the bacteria's survival after gelation and without any source of carbon. The largest disintegration of gels occurred in acidic pH. Moreover, the effect of alginase on crosslinked bacterial gels and synthetic alginate were very similar. The survival of bacterial cultures in gel and their continuous release are significant findings in the development of novel bioinoculants based on this new concept.
|
|
|
Uses of active compounds from honey in cosmetic products
Balášová, Patricie ; Langová, Denisa (referee) ; Skoumalová, Petra (advisor)
The bachelor thesis was focused on the preparation and characterization of extracts and liposomes with active substances from chosen types of honey with the aim to apply these extracts to the cosmetic products. The extraction of active substances from chosen material was optimized during the work. As the most suitable organic solvent for extraction was chosen diethyl ether. All the extracts were tested on the content of total polyphenols, sugars and antioxidation activity. The final samples were also tested on the content of flavonoids. Extracts were encapsulated to the liposomes, which were tested especially for their antioxidation activity, size and stability. Then, extracts and liposome particles were applied to the cosmetic products. Cosmetic creams and gels were prepared and tested for antioxidation activity and antimicrobial activity against the strains Serattia marcescens and Micrococcus luteus. Antimicrobial activity of gels was proved especially against the strain of grampositive bacterias – Micrococcus luteus. From this point of view another one testing strain was chosen – Propionibacterium acnes. Finally, the chosen liposomes were tested for their contact with human cells, immortalized keratinocytes HaCat. No cytotoxic effect was observed and tested materials can be applied to cosmetics against acne.
|
|
|
Preparation of antimicrobial gels with plant extract and oils
Benešová, Markéta ; Hoová, Julie (referee) ; Skoumalová, Petra (advisor)
This bachelor thesis was focused on studying antimicrobial effects of natural plant extracts and their subsequent application. The research was mainly focused on the antioxidant and antimicrobial activity of plant extracts and liposomal particles with their contents. Theoretical part of thesis was focused on the topic of natural antimicrobial and antioxidant substances, problems with bacterial resistance as well as describing features and attributes of used herbs, and characterization of gels and liposomes. Within the experimental part of thesis, three types of extracts (aquatic, ethanol and oil), prepared from 10 different types of plants, were described. The content of phenolic, flavonoid substances, also antioxidant and antimicrobial activity were then determined. After that, the contents of all extracts were encapsulated into liposomes, and size, stability, encapsulation activity, also antioxidant and antimicrobial activity of those liposomes were determined. The size distribution was wide, but in terms of the measured zeta potential, most of the particles were stable. All prepared extracts and liposomes containing them were tested for their antimicrobial activity. The tests were performed on a gram-positive genus of Micrococcus luteus and a gram-negative type of Serratia marcescens. The most effective oil extracts against both species were eucalyptus and fir, as well as oil extract of cloves, along with aqueous extracts of mustard seeds, cloves and juniper, or ethanol extract of anise which also has high antimicrobial effects. Finally, these extracts and liposomes were applied into the gels, which could be found useful in the pharmaceutical industry, as an alternative to externally used antibiotics, or in the cosmetic industry.
|
|
|
Encapsulation of some enzymes into organic particles
Hazuchová, Eva ; Obruča, Stanislav (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on encapsulation of some enzymes into organic particles. The theoretical part is aimed to enzymes, their general characteristics, structure, activity and use, and to encapsulation techniques. Some methods used for analysis of particles, namely the determination of the distribution of particle size using dynamic light scattering, and determining the stability of the particles by the zeta potential, are described too. The experimental part describes methods of preparing particles, methods of determining the encapsulation efficiency and methods for determining particle size and stability. During the experiment part four types of enzymes were encapsulated, partly by manual preparation and partly by encapsulator. Encapsulation efficiency, size and stability of prepared particles were determined too. The particles were exposed to artificial intestinal, gastric and bile juices, as well as the effect of model foods. Subsequently, their long-term stability was observed.
|
|
|
Encapsulation of soil bacteria in hydrogel carriers
Orišková, Sofia ; Smilek, Jiří (referee) ; Sedláček, Petr (advisor)
The goal of this bachelor thesis was both to review existing literature regarding the topic of inoculation of soil bacteria and test a relevant encapsulation method and optimize it. The evaluation process involved the study of various encapsulation techniques that involve hydrogel carriers suitable for agronomic purposes. Encapsulation allows controlled release of soil bacteria, and protects and stabilizes it, while ensuring longer shelf life. For the practical testing, Cupriavidus necator H16 was chosen as a nitrogen fixing bacteria for the inoculation. Through an ionic gelation method, it was encapsulated into alginate carriers, forming matrix microcapsules. Sodium alginate reacts with the cross-linking agent calcium chloride to form the capsules. The impact on the quality of the product was tested through several variables. What was revealed was that molecular weight of alginate was proven to have a significant impact. Alginate with higher molecular weight was shown to be suitable for the given system. The most desirable environment was distilled water or a TRIS-HCl buffer. However, the TRIS-HCl was unsuitable in cases of retrieving a dry product by lyophilization. Eventually, the viability of encapsulated cells was examined, and it was proven that encapsulated bacteria endure the process of encapsulation in the above-mentioned environment and they were gradually released from the carrier.
|
guest ::
