Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms for Magnetic Cell Separation

Microfluidic platforms for magnetic cell separation were developed and investigated for isolation of magnetic particles and magnetically tagged cells from a fluidic sample. Two types of magnetic separation platforms were considered: an Isodynamic Open Gradient Magnetic Sorter (OGMS) and a multistage bio-ferrograph. Miniaturized magnets were designed using magnetostatic simulation software, microfluidic channels were fabricated using microfabrication technology and magnetic separation was investigated using video microscopy and digital image processing. The isodynamic OGMS consisted of an external magnetic circuit and a microfabricated channel (biochip) with embedded magnetic elements. The biochip is placed inside the magnetic field of the external circuit to obtain nearly constant energy density gradient in the portion of the channel used for separation. The microfabrication process involved improving adhesion of thick SU-8 to Pyrex, forming enclosed channels using a low temperature SU-8 adhesive bonding, and fabricating patterned plating molds on both sides of the bonded wafers. Adhesion of SU-8 to Pyrex was improved by using a highly crosslinked thin SU-8 adhesion layer, and enclosed microchannels were fabricated using selectively exposed SU-8 bond formation layers. Electroplating molds were fabricated using KMPR photoresists and were integrated on both sides of the bonded wafers. The multistage bio-ferrograph consisted of a microfabricated enclosed channel placed on the surface of a multi-unit magnet (4 trapezoidal magnets placed in series) assembly such that magnetic cells from a flowing stream would be deposited on designated locations. The OGMS was able to deflect magnetic particles by 500-1000 microns and the capture efficiencies of magnetic particles and cells with the multistage bio-ferrograph were 80-85 percent and 99.5 percent, respectivel

Mems (Micro-Electro-Mechanical-Systems) Based Microfluidic Platforms for Magnetic Cell Separation

Microfluidic platforms for magnetic cell separation were developed and investigated for isolation of magnetic particles and magnetically tagged cells from a fluidic sample. Two types of magnetic separation platforms were considered: an Isodynamic Open Gradient Magnetic Sorter (OGMS) and a multistage bio-ferrograph. Miniaturized magnets were designed using magnetostatic simulation software, microfluidic channels were fabricated using microfabrication technology and magnetic separation was investigated using video microscopy and digital image processing. The isodynamic OGMS consisted of an external magnetic circuit and a microfabricated channel (biochip) with embedded magnetic elements. The biochip is placed inside the magnetic field of the external circuit to obtain nearly constant energy density gradient in the portion of the channel used for separation. The microfabrication process involved improving adhesion of thick SU-8 to Pyrex, forming enclosed channels using a low temperature SU-8 adhesive bonding, and fabricating patterned plating molds on both sides of the bonded wafers. Adhesion of SU-8 to Pyrex was improved by using a highly crosslinked thin SU-8 adhesion layer, and enclosed microchannels were fabricated using selectively exposed SU-8 bond formation layers. Electroplating molds were fabricated using KMPR photoresists and were integrated on both sides of the bonded wafers. The multistage bio-ferrograph consisted of a microfabricated enclosed channel placed on the surface of a multi-unit magnet (4 trapezoidal magnets placed in series) assembly such that magnetic cells from a flowing stream would be deposited on designated locations. The OGMS was able to deflect magnetic particles by 500-1000 microns and the capture efficiencies of magnetic particles and cells with the multistage bio-ferrograph were 80-85 percent and 99.5 percent, respectivel

Wissensstandsanalyse zu Qualität, Verbraucherschutz und Verarbeitung ökologischer Lebensmittel

Zielsetzung des Projektes war es, den aktuellen Stand des Wissens zur Qualität und Verarbeitung ökologischer Lebensmittel sowie zum Verbraucherschutz aufzuzeigen und zu bewerten. Das Projektteam setzte sich aus Wissenschaftlern des Forschungsinstituts für biologischen Landbau (Deutschland und Schweiz), des Büros für Lebensmittelkunde, des Forschungsrings für Biologisch-Dynamische Wirtschaftsweise e.V. sowie des Fachgebiets Ökologische Lebensmittelqualität und Ernährungskultur der Universität Kassel zusammen. In dem zeitlich sehr begrenzten Projekt fokussierte die Arbeitsgruppe die Betrachtung auf folgende Themenkomplexe und Produktgruppen: Bereich Qualität - Ernährung - Sensorik - Ökospezifische Qualitäten - Authentizität und Rückverfolgbarkeit Bereich Verarbeitung - Rohwaren/Lagerung und Technologien für die Produktgruppen: -- Getreide -- Milch -- Fleisch -- Obst und Gemüse und Erzeugnisse aus diesen - Nachhaltigkeit im Unternehmen und entlang der Prozesskette - Verpackung Vorhandenes Wissen, aktuelle Fragestellungen und Entwicklungsrichtungen wurden nach thematisch angepassten Vorgehensweisen identifiziert und anhand internationaler Literatur und Experteninterviews diskutiert. Zu allen Themenkomplexen wurden kurze und allgemeinverständliche Reports erstellt, die einen schnellen und fundierten Überblick zum aktuellen Stand des Wissens und zu eventuellen Wissenslücken geben. Der Abschlussreport wurde in deutscher und englischer Sprache veröffentlicht. Insgesamt wurde festgestellt, dass in den betrachteten Themenkomplexen erheblicher Bedarf an Forschung und Entwicklung sowie an Wissenstransfer besteht. Neben einer Reihe von Detailfragen sind grundlegende Themen, wie beispielsweise das Anforderungsprofil an eine „ökologische Verarbeitung“, nicht hinreichend erforscht und geklärt. Diese Arbeiten sind jedoch Voraussetzung für die Bearbeitung von Detailthemen, da hier Aufgabenstellungen, Schwerpunktsetzungen und Methoden definiert werden

The quest for celiac-safe wheat

Gluten proteins from wheat have the unique property to interact with each other and form a network in dough preparation. In this gluten network gas bubbles can be retained that are produced by yeast, which is added during dough preparation. The result is a voluminous, viscoelastic dough for bread making. Besides these network forming properties, gluten proteins contain remarkably high amounts of the amino acids proline and glutamine. Therefore, these proteins can not be degraded completely in the human gastrointestinal tract and so called epitopes are generated in the small intestine after ingestion of gluten containing foods such as bread and cookies. Intolerance to gluten proteins can cause inflammation of the small intestine, which leads to villous atrophy (flatten mucosa) and malabsorption. This intolerance to gluten proteins is also called celiac disease. The with celiac disease occurring inflammation can lead to many symptoms such as malnutrition, weight loss, stomach pain, diarrhea, dermatitis and in the worst case lymphoma. In children, celiac disease can cause growth retardation. Gluten proteins from rye and barley, because of their similarity to gluten proteins from wheat and high proline and glutamine content, can also cause celiac disease. Celiac disease patients therefore have to avoid life-long all food products containing wheat, rye, and barley (gluten-free diet). Not only gluten protein intake but also genetic susceptibility is necessary to develop celiac disease. Therefore, relatives of celiac disease patients have a highly increased risk to develop celiac disease. About 0.52% of the Western population suffers from celiac disease of which 7097% is undiagnosed, and the prevalence of celiac disease is still increasing. The reason for this may be the consumption of many bread, cookie and pasta products, but also because wheat constituents, such as gluten and starch, are increasingly used as food additive in soups, sauces, sausage, candy, ice-cream, and even in medicines. Because bread wheat originated thousands of years ago by fusion of three different grass species, many different gluten proteins exist. Pasta wheat originated from two of the three grass species and lacks the species that contains most of the celiac disease epitopes. Not all gluten proteins can be removed because baking properties might be lost. For analysis of the presence of celiac disease epitopes, it is important that all gluten proteins are extracted from the wheat kernels. Therefore, an extraction protocol was developed to extract as many gluten proteins as possible, which allows analysis of many samples at the same time. Because thousands of different wheats exist that have never been tested for celiac disease epitopes, this extraction and detection method was applied to analyze whether modern wheats, which are used by breeders, exist with lower amounts of celiac disease epitopes. These modern wheats were subsequently compared to old wheats collected from all over the world. From these analyses it seemed that there was an increase in celiac disease epitopes in modern wheats. This might be the reason for the increase of prevalence of celiac disease. For future breeding of bread wheat it is important to select and breed not only for high yield, disease/pest resistance, and baking quality, but also for the (reduced) presence of relevant celiac disease epitopes. In older bread and pasta wheats, we observed that fewer celiac disease epitopes are present. Knowing this, a more celiac-safe bread wheat could be developed by performing crossings with a selection of wheats. In the analysis of wheat lines that miss specifically genetic parts of one of the three grass species from which bread wheat evolved, it appeared that if the part is removed that encodes celiac disease epitopes to which most patients respond, the dough properties improved compared to the control dough. By addition of similar proteins from oat (avenins), the dough properties improved even more. These gluten proteins from oat are tolerated by most celiac disease patients. The results show that it is feasible to develop wheat that contains less celiac disease epitopes without decreasing dough properties. Celiac disease patients, however, respond differently to different celiac disease epitopes which complicates the development of wheat that is suitable for all celiac disease patients. The research performed in this thesis shows that selection of wheat for the presence of celiac disease epitopes is extremely relevant because it can reduce the number of celiac disease patients in the future. At the same time, we demonstrate that celiac-safe wheat can still maintain good baking properties. Diagnosed celiac disease patients will benefit as well from celiac-safe wheat because exposure to ‘hidden’ gluten proteins will decrease. <br/

Chemical cleaning of starch based deposits from hard surfaces

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN032846 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

ALTERNATIVE PROTEINS FEEDING THE WORLD: INCLUSION OF CRICKET POWDER IN CEREAL- BASED PRODUCTS

With the growing population worldwide and subsequently, the increasing demand for protein from livestock (poultry, fish, pigs and cattle) causes concern and future challenges. Entomophagy (the practice of consuming insects) can be promoted as an alternative and sustainable food source. Although there are around 1900 edible insect species globally, these are mainly consumed in developing countries due to their nutritional composition and ease of access. For instance, crickets are high in protein, fibre and low in carbohydrate, making them suitable to feed the world as an alternative food. The objective of this research was to understand the implications when using cricket powder fortificants within baked products. Three different sample replacement levels, wheat flour and cricket powder – 30% (WW+CP), wheat flour, cricket powder, quinoa- and Khorasan flour – 30:20:20% (WW+CP+Q+KH) and wheat flour, cricket powder, quinoa- Khorasan flour and mixed seeds – 30:20:20:25% (WW+CP+Q+KH+MS), were tested against a control sample (wheat flour – WW). Dough and bread samples were subjected to rheological, technological, chemical and sensory analysis to determine the individual analysis parameters. A negative linear correlation was observed between the number of inclusions within samples. Thus, impacting the rheological dough parameters, particularly a statistical significance (p < .05) for secondary parameters (protein weakening, starch gelatinisation and enzyme degradation). Crumb brightness and slice volume parameters decreased through the C-Cell illumination system as the replacement levels increased for all treatments. WW+CP+Q+KH+MS samples showed a decrease in the area occupied by air cells, the average air cell diameter, and cell wall thickness. However, the number of gas air cells increased for WW+CP+Q+KH and WW+CP+Q+KH+MS, indicating a good fermentation process within the bread samples. Texture profile analysis (TPA) was monitored at 1, 3, 5 and 7 days, showing a positive correlation between the higher number of flour inclusions and a reduced hardness within samples. Likewise, resilience decreased as the replacement levels increased for all treatments. Bread samples were analysed for nutritional composition and revealed an increase in crude- protein, fat and fibre as the replacement levels increased. This correlated with a positive linear increase between the increase in replacement levels and the macronutrients. Furthermore, this directly impacted the texture for sample WW+CP+Q+KH+MS, as it maintained the softest crumb reducing the staling rate. Finally, bread samples made with the combination of WW+CP+Q+KH+MS, showed a liking by 145 untrained panellists (appearance – 57%, taste – 74%, texture – 64%). Data collected highlighted a practical use of cricket powder, ancient grains and mixed seeds to produce enriched bread products. Meanwhile, a JISC survey found that consumers worldwide prefer insects as agricultural feed rather than a direct food source (r = .6). However, this changed when participants heard about crickets’ potential health benefits, and a shift to accepting crickets as a direct food source was noticed (r = .89). Furthermore, the food neophobia levels showed a decrease compared to previous studies, suggesting more acceptance of this alternative protein

Microfluidics: a new look at cell migration analysis

This thesis explores the development and employment of microfluidic devices as a tool for studying the effect of the surrounding environment on embryonic stem cells during the migration phenomena. Different single-cell microchips were designed and manufactured to study mouse embryonic fibroblasts (MEFs) migration towards an environmental variation (increase of serum concentration in the culture medium) that was expected to function as a motility stimuli. Considering the experimental, cells were injected into the microchips chambers and individually isolated by dedicated cell traps with view to a single-cell analysis. Once fribroblasts were attached to the surface, culture medium with an increased serum level was subsequently injected in an adjacent chamber to promote the formation of a serum concentration gradient. The gradient established between the chambers could be sensed by the fibroblasts and thus triggered the cells mobilization towards and in the direction of the richer serum medium. Additionally, the experiment allowed the observation of MEFs’ structural reorganization when migrating through micro-tunnels containing widths below the cell size, suggesting a cytoskeleton rearrangement on account of the nutritional stimulus introduced. Furthermore, results indicate that fibronectin promotes MEFs adhesion to the substrate and that MEFs migration is characterized as haptotactic

Design and development of a microfluidic platform for use with colorimetric gold nanoprobe assays

Due to the importance and wide applications of the DNA analysis, there is a need to make genetic analysis more available and more affordable. As such, the aim of this PhD thesis is to optimize a colorimetric DNA biosensor based on gold nanoprobes developed in CEMOP by reducing its price and the needed volume of solution without compromising the device sensitivity and reliability, towards the point of care use. Firstly, the price of the biosensor was decreased by replacing the silicon photodetector by a low cost, solution processed TiO2 photodetector. To further reduce the photodetector price, a novel fabrication method was developed: a cost-effective inkjet printing technology that enabled to increase TiO2 surface area. Secondly, the DNA biosensor was optimized by means of microfluidics that offer advantages of miniaturization, much lower sample/reagents consumption, enhanced system performance and functionality by integrating different components. In the developed microfluidic platform, the optical path length was extended by detecting along the channel and the light was transmitted by optical fibres enabling to guide the light very close to the analysed solution. Microfluidic chip of high aspect ratio (~13), smooth and nearly vertical sidewalls was fabricated in PDMS using a SU-8 mould for patterning. The platform coupled to the gold nanoprobe assay enabled detection of Mycobacterium tuberculosis using 3 8l on DNA solution, i.e. 20 times less than in the previous state-of-the-art. Subsequently, the bio-microfluidic platform was optimized in terms of cost, electrical signal processing and sensitivity to colour variation, yielding 160% improvement of colorimetric AuNPs analysis. Planar microlenses were incorporated to converge light into the sample and then to the output fibre core increasing 6 times the signal-to-losses ratio. The optimized platform enabled detection of single nucleotide polymorphism related with obesity risk (FTO) using target DNA concentration below the limit of detection of the conventionally used microplate reader (i.e. 15 ng/μl) with 10 times lower solution volume (3 μl). The combination of the unique optical properties of gold nanoprobes with microfluidic platform resulted in sensitive and accurate sensor for single nucleotide polymorphism detection operating using small volumes of solutions and without the need for substrate functionalization or sophisticated instrumentation. Simultaneously, to enable on chip reagents mixing, a PDMS micromixer was developed and optimized for the highest efficiency, low pressure drop and short mixing length. The optimized device shows 80% of mixing efficiency at Re = 0.1 in 2.5 mm long mixer with the pressure drop of 6 Pa, satisfying requirements for the application in the microfluidic platform for DNA analysis.Portuguese Science Foundation - (SFRH/BD/44258/2008), “SMART-EC” projec