bioactivity of nisin-loaded pluronic microspheres challenged by blood proteins julie auxier dr....
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Bioactivity of Nisin-Loaded Pluronic Microspheres Challenged by Blood Proteins
Julie AuxierDr. Joseph McGuire - BioengineeringOregon State UniversityHHMI Summer 2008
Infected Hospitals
• Infections are the 4th largest killer in US
• In the US in 2005 there were:▫ 94,360 invasive MRSA infections
▫ 18,650 associated deaths
• Costs millions annuallyHealthcare-Associated
Community-Associated
Source: ABCs Population-based surveillance System, Klevens et al. JAMA 2007
MRSA Infections in 2005
Infected Hospitals
• Problems from implanted devices:▫ Clotting▫ Bacterial adhesion▫ Proliferation
• Treat with heparin and other anticoagulants▫ Risk of platelet depletion, excessive bleeding
Blood Proteins •Albumin, globulin, fibrinogen•Fibrinogen key in coagulation
Intrinsic Pathway
Extrinsic Pathway
Tissue Damage
Tissue Factor III
Factor VII Tissue Factor Complex
Clotting Factor VII
Activated Proenzymes, usually Factor XIII
Platelet Factor PF-3
Clotting Factors VIII, IX
Factor X Activator Complex
Ca2+
Ca2+
FibrinogenFibrin
Prothrombin Thrombin
Factor X
Prothrombinase
Common Pathway
Prevention with Pluronic® F108
HYDROPHOBIC
HYDROPHILIC
HYDROPHOBICSURFACE
PEO
PEO
PPO
Irradiating F108 Surfaces• Hydrophobic association not permanent
• Irradiation creates a covalent bond between the F108 and the silanized silica
• Fluid flow will not wash away F108
HYDROPHOBIC
PROTEI
N
How Brush Layer Functions
Nisin - Lantibiotic• Bacteriocin: peptide produced by bacteria to
inactivate other like bacteria
• Naturally made from bacteria Lactococcus lactis
• Used in food products: preservative, making cheese
Hydrophobic Surface
How Nisin Kills Bacteria
Purpose
Challenge Nisin-loaded F108 silica
microspheres with blood proteins to
quantify protein adsorption to the
brush layer.
Predictions
Microspheres treated with irradiated
F-108 will deflect protein
adsorption throughout the entire
trial; however, the efficacy of
nisin treated samples will decline
with time.
Efficacy Test:Silanize bare silica microspheres (~1μm in diameter)
Covalently bond F108 by γ irradiation
Plate samples with diluted Pediococcus pentosaceus
Add nisin
Challenge with blood proteins
Quantify with colony counting
Silanized Silica Microspheres
Horse Plasma Nisinγ F108
NisinHorse Plasma
No Nisin
Horse Plasma
Horse Plasma
M MN MF MFN
MS MNS MFS MFNS
Effect of Nisin on Pediococcus
PED MNMFN
MFNS MNS
Results
Results
Results
Future Research • Further work on behavior of protein adsorption
• Test platelet adhesion by challenging the same surfaces with platelet rich plasma
• Apply the coating to devices in vivo
AcknowledgementsDr. Joseph McGuire
Matthew Ryder
McGuire Lab Group
Dr. Skip Rochefort
Dr. Kevin Ahern
Howard Hughes Medical Institute
Johnson Internship Program