April 5, 2007Initial Prototype Presentation

PE

M

PemPlant Co.

Maricela DelgadilloKay FurmanYushan Kim

Overview

• Update▪ Methylene blue staining: more results▪ Contact angle results▪ Mechanical force probe update

• Initial prototype• Future characterization steps

Methylene Blue Staining

• glass: UV vis. possible

• Ti: opaque, only qualitative analysis possible.

Contact Angle Measurements

• Samples Tested▪ Bare Ti, glass, 2.0/2.0

crosslinked, 3.0/3.0 crosslinked and uncrosslinked

• DI water used as Solvent• Average of three

measurements

Reference Data

• For 3.0/3.0 system▪ Contact: 61▪ Receding: <10

• For 2.0/2.0 system▪ Contact: <10

Yang, S. Y.; Mendelsohn, J. D.; Rubner, M. F. Biomacromolecules. 2003, 4 (4), 987-94

Results for Glass System

• Glass▪ Contact: 83.7º▪ Receding: 73º

• 2.0/2.0 Crosslinked▪ 10.6º

• 3.0/3.0 Crosslinked▪ 29.45º

• 3.0/3.0 Uncrosslinked▪ 12.4º

2.0/2.0 x-linked

Glass

Results for Ti System

• Bare Ti▪ 38.3º

• 2.0/2.0 Crosslinked▪ 31.35º

• 3.0/3.0 Crosslinked▪ 80.2º

• 3.0/3.0 Uncrosslinked▪ 67.4º

2.0/2.0 x-linked

3.0/3.0 un x-linked

Results

• Bare Ti Lit review measures about 100º▪ Lower value may be due to surface

roughness• Significant increase in contact angle

measurements on Ti surfaces as compared to Glass▪ Polymer film on Ti results in a more

hydrophobic surface▪ Glass system results in a more hydrophillic

surface

Initial Prototype

• Cleaning: acetone wipe, ethanol sonication

• Layers:▪ Polyanion (PAA) 15min,

rinse 3x (2, 1, 1 min)▪ Polycation 15 min,

rinse 3x (2, 1, 1 min)

Polycation pH Bilayers Crosslinking?

PAH 2.0/2.0 9.5 80°C, 1h

PAAm 3.0/3.0 5.5 130°C, 2h, vac

Next Characterization Steps

• Mechanical Force Probe▪ Initial training completed▪ Practice data analyzed

• Stability tests▪ Wear test▪ Antibacterial testing over prolonged time periods ▪ Aqueous environment film durability▪ Shelf life test: Characterize our oldest films

Final Prototype

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Mechanical Wear Test Motivation

• Simulate handling during implantation procedure

• Operating room conditions:▪ Devices handled sterilely▪ Potential handling by surgical

nurse and physician▪ Nitrile glove protected hands

• Risk of coating removal:▪ Loss of antibacterial coating▪ Potential for bacterial infection from:

◦ Skin exposure (wound)◦ Air

Mechanical Wear Test

• Goal: Assess coating delamination risk from handling

• Parameters:▪ Glove probe surface▪ Typical handling load▪ Number of cycles

• Design and build testing apparatus• Standard Test Method

▪ ASTM G99-04▪ “Wear testing with a Pin-on-Disk Apparatus”

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Wear Test Apparatus

• Equipment:▪ Variable speed motor▪ Disk and pin setup▪ Sample stand▪ Gloved probe

• Design under developmentPemPlant Co.

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Wear Test Data Analysis

• Need tool to assess coating wear• Ideal analysis method:

▪ Quantitative ▪ Comparative ▪ Sensitive ▪ Timely

• Current characterization methods:▪ MFP (long T)▪ Methylene blue (less sensitive)

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Gantt Update

• Website: http://web.mit.edu/3.042/team1_07/Website/Website/Contains this and all previous presentations