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Application of Atomic Force Microscopy to measure the interaction forces between infectious microorganisms and biomaterials surfaces.

Projectomschrijving

Biomaterialen worden toegepast ter vervanging van lichaamseigen weefsels. De oppervlakken van zulke lichaamsvreemde kunststoffen en metalen hebben een sterke aantrekkingskracht op bacteriën. Het behandelen van patiënten met een ontstoken prothese is een lange, kostbare weg. Het mechanisme waarmee bacteriën aan een biomateriaal oppervlak hechten kan worden onderzocht met een atomic force microscope (AFM), die bij voorbeeld de hechtingskracht van een bacterie kan meten. Het veranderen van het oppervlak van het biomateriaal kan de hechting verminderen. Met behulp van AFM is ontdekt dat een polymere borstel als oppervlak gunstig is en dat sommige eiwitten waarvoor de bacterie specifieke receptoren heeft, de hechting juist versterkt. Het kiezen van de juiste coating van een biomateriaal, is dus wezenlijk.

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Samenvatting van de aanvraag

Biomaterials implants have become indispensable in modern medicine for the restoration of human function, after oncological surgery, trauma or wear. Despite the success of many biomaterials implants, infection remains the most important reason for failure, at the expense of enormous costs to the health care system and patients discomfort. Microorganisms on a biomaterials implant grow in a slime-embedded form or so-called biofilm mode of growth, that protects them against the host immune system and antimicrobials. Consequently, once a biomaterials implant becomes infected, removal is often the only solution. Biofilm formation is in essence an interaction between the biomaterials surface and the microbial cell surface. Over the past it has been attempted to understand the adhesion of microorganisms to surfaces on the basis of macroscopic observations, including the measurement of hydrophobicity and electrical charge of the interacting surfaces. Although this has led to considerable insights in the process of microbial adhesion, subsequent development of adhesion-resistant or so-called non-fouling coatings for application on biomaterials implants has not been successful. This indicates that we still do not understand the mechanism of microbial adhesion to an extent that enables us to control it. Atomic force microscopy (AFM) has made it possible to study microbial interactions with surfaces at a nanoscopic level, therewith making it possible to gain a further understanding of the mechanisms of microbial adhesion. AFM offers, however, many more interesting possibilities, than just microscopic ones. The interaction forces between the tip of the AFM apparatus, or any other material of synthetic or biological origin attached to the tip, and a surface can be adequately measured with AFM. In the past we have published a comparison of different experimental procedures to measure these interaction forces and have applied AFM to study the initial interaction forces between microorganisms, and between microorganisms and model hydrophobic and hydrophilic surfaces. The initial interaction forces between microorganisms and a biomaterials surface is reversible, but due to exopolymer production by the adhering organisms bonding strengthens over time, finally to become irreversible. This transition from reversible to irreversible microbial adhesion is clinically most relevant, as it is associated with the resistance of the biofilm mode of growth toward current treatment modalities. The requested microscope will, in contrast to existing AFM?s, allow to arrest the movement of the tip during measurement and it leave at a fixed distance. This enables to measure the dynamics in the interaction forces between adhering microorganisms and a biomaterials surface. In addition, the microscope has a much better control of the vertical cantilever displacement, making it possible to measure force-distance curves between two relatively soft surfaces, such as a microbial cell surface and a protein-covered biomaterials implant surface after explantation from the human body. The new AFM will be placed within the Department of Biomedical Engineering, as a part of the institute BMSA. BMSA provides a platform for combining clinical and more fundamentally oriented research projects, through the involvement of many departments from the University Hospital Groningen in the institute. The AFM will be used in the following research areas in line with one of the general goals of BMSA to better understand microbial interaction forces with biomaterials surfaces: a. development of non-fouling polymer brush coatings; b. coaggregation between E. faecalis strains isolated from clogged biliary stents; c. coaggretation between oral bacterial pairs and enamel surfaces after exposure to dentifrices; d. interaction between bacteria and orthopedic implant surfaces after retrieval from the human body; e. interaction between bacteria and yeast with the surfaces of silicone rubber voice prostheses; f. infection resistance of contact lenses.

Onderwerpen

Kenmerken

Projectnummer:
91105005
Looptijd: 100%
Looptijd: 100 %
2005
2009
Onderdeel van programma:
Projectleider en penvoerder:
Prof. dr. H.C. Mei
Verantwoordelijke organisatie:
Universitair Medisch Centrum Groningen