Projects

The anti-listerial properties of biodegradable polylactide coatings modified with titanium dioxide have been studied. Free standing films were prepared by casting solutions prepared from titanium dioxide and previously extruded polylactide. It was demonstrated that polylactide alone could support 2.84 ± 0.10 log CFU reduction of Listeria monocytogenes when incubated at 23 °C for 2 h. However, the log reduction for Listeriacould be increased to >4 log CFU with titanium dioxide:polylactide composites illuminated with UV-A. The inactivation kinetics of L. monocytogenes followed a diphasic die-off with an initial 30 min lag period then a progressive decline in bacterial levels over a further 90 min period. The anti-listeria effect of polylactide:titanium dioxide films was dependent on illumination with UV-A but independent on the concentration of TiO2incorporated in the film within the range of 1–5% w/w. The mode of L. monocytogenesinactivation was via direct contact of the pathogen with the polylactide, in addition to the generation of oxygen radicals produced by excitation of the titanium dioxide. The composite film illuminated with UV-A was equally effective against SalmonellaTyphimurium and Shiga toxin producing Escherichia coli. The coating was stable to 5 repeated sanitation cycles consisting of detergent and sodium hypochlorite rinses. The polylactide-titanium dioxide coating shows potential as an antimicrobial coating although further work is required to assess if the protective film can function under commercial conditions. 

 

Background

Antimicrobial resistance is a great concern in the medical community, as well as food industry. Soy peptides were tested against bacterial biofilms for their antimicrobial activity. A high throughput drug screening assay was developed using microfluidic technology, RAMAN spectroscopy, and optical microscopy for rapid screening of antimicrobials and rapid identification of pathogens.

Methods

Synthesized PGTAVFK and IKAFKEATKVDKVVVLWTA soy peptides were tested against Pseudomonas aeruginosa and Listeria monocytogenes using a microdilution assay. Microfluidic technology in combination with Surface Enhanced RAMAN Spectroscopy (SERS) and optical microscopy was used for rapid screening of soy peptides, pathogen identification, and to visualize the impact of selected peptides.

Results

The PGTAVFK peptide did not significantly affect P. aeruginosa, although it had an inhibitory effect on L. monocytogenes above a concentration of 625 µM. IKAFKEATKVDKVVVLWTA was effective against both P. aeruginosa and L. monocytogenes above a concentration of 37.2 µM. High throughput drug screening assays were able to reduce the screening and bacterial detection time to 4 h. SERS spectra was used to distinguish the two bacterial species.

Conclusions

PGTAVFK and IKAFKEATKVDKVVVLWTA soy peptides showed antimicrobial activity against P. aeruginosa and L. monocytogenes. Development of high throughput assays could streamline the drug screening and bacterial detection process.

General significance

The results of this study show that the antimicrobial properties, biocompatibility, and biodegradability of soy peptides could possibly make them an alternative to the ineffective antimicrobials and antibiotics currently used in the food and medical fields. High throughput drug screening assays could help hasten pre-clinical trials in the medical field.

Wound Healing: Electrotaxis of Pathogenic Bacterial Cells Using Microfluidics

Electrotaxis or Galvanotaxis is the display of migration pattern of cells towards varying electrical potential. Although electrotaxis has been extensively studied for mammalian cells, there have been no in-depth investigations of electrotaxis of bacterial cells, i.e., more specifically pathogenic bacterium. From the BioNano Lab of University of Guelph, we have designed and fabricated nanoporous microfluidic platforms using photolithography and soft lithography techniques for investigating the motility dynamics of single cells of pathogenic Pseudomonas aeruginosa and Acinetobacter baumannii to varying electrical potential and wound healing chemical agents. The orientation and migratory behaviour of single cells such as velocity, migration index, trajectories to varying strengths of multi-cue such as electric field and chemical concentrations  were systematically characterized using a series of experiments. The results of this project provides novel insights and strategies towards development of electroceutical solutions with applications for wound healing, prevention of biofouling in dairy-food processing, and oil transport in petroleum industries. Coexisting electrical stimulation and chemical treatment could serve as a potential technique for rapid wound healing.

Biosensors, as an application for animal health management, are an emerging market that is quickly gaining recognition in the global market. Globally, a number of sensors being produced for animal health management are at various stages of commercialization. Some technologies for producing an accurate health status and disease diagnosis are applicable only for humans, with few modifications or testing in animal models. Now, these innovative technologies are being considered for their future use in livestock development and welfare. Precision livestock farming techniques, which include a wide span of technologies, are being applied, along with advanced technologies like microfluidics, sound analyzers, image-detection techniques, sweat and salivary sensing, serodiagnosis, and others. However, there is a need to integrate all the available sensors and create an efficient online monitoring system so that animal health status can be monitored in real time, without delay. This review paper discusses the scope of different wearable technologies for animals, nano biosensors and advanced molecular biology diagnostic techniques for the detection of various infectious diseases of cattle, along with the efforts to enlist and compare these technologies with respect to their drawbacks and advantages in the domain of animal health management. The paper considers all recent developments in the field of biosensors and their applications for animal health to provide insight regarding the appropriate approach to be used in the future of enhanced animal welfare. 

Screening Ontario Grown Onion Varieties for Antioxidant Properties

Agricultural products are in great demand in nutra-pharmaceutical and biomedical industries due to their potential health benefits to humans. Among all vegetables, onions are the most widely and largely consumed vegetable. Onions are rich in phenolic such as flavonoids, and anthocyanins. Flavonoid has the potential to be antioxidant, antibacterial, anti-inflammatory and anticancerous. Studies indicate that the decline in cardiovascular diseases, breast cancer, diabetes, inflammation and osteoporosis could be linked to the consumption of flavonoid based foods. In this study, we screen Ontario grown onion varieties namely Stanley, Safrane, Fortress, Lasalle and Ruby Ring for their antioxidant properties, and isolate the flavonoids present in them and the best Ontario grown onion variety was chosen for developing functional food traits. Extraction with solvents, low polarity water and supercritical carbon dioxide produced flavonoids such as kampferol, quercetin, myricetin, isorhamnetin from all the 5 onion varieties. High Performance Liquid Chromatography analysis of the extracted flavonoids showed the presence of sulfur containing compounds. The antioxidant efficacy of these extracts evaluated by oxygen radical scavenging assays, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays provided a better understanding of the nutrient profile of the Ontario grown onion varieties. Identification, enhancement and development of market quality traits such as antioxidants properties of Ontario-grown onions enhances their marketability as nutraceutical products, as natural antibiofilm coating agent for improved shelf life of packaged food and as a preservative in processed food.

http://www.hollandmarshgold.com/research-projects.html

 

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Contact Us

Bionanotechnology Laboratory
Suresh Neethirajan

School of Engineering
University of Guelph
Guelph, Ontario
Canada N1G 2W1

Office:
Room 3513 - Richards Building
50 Stone Road East

Lab: THRN 2133 BioNano Lab

Phone: (519) 824-4120 Ext 53922
Fax: (519) 836-0227

E-mail: sneethir@uoguelph.ca

 
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