Hydrophilic Coating - Living tissue interaction
Tailoring polymer friction, wear and hydrophilic lubricity of intermittent catheters
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Hydrophilic Coating - Living tissue interaction
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Content
• Introduction to hydrophilic coating technology
• Development and applications of hydrophilic coatings on urinary catheters
• Evaluation of lubricious coatings in contact with living tissue
• Conclusive remarks
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Hydrophilic Coating - Living tissue interaction
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Hydrophilic coating on medical device - benefits
Low friction facilitates insertion & removal
Improve the biocompatibility
Minimize bacterial adhesion
Low friction minimizes injury
Reduce biofilm formation
Drug delivery
Reduce formation of encrustations
Antimicrobial delivery system
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Hydrophilic Coating - Living tissue interaction
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Device, Substrate- and Coating Materials
Medical devices
Coating Polymers
•
•
•
•
•
•
•
Synthetic:
• Poly(vinylpyrrolidone) - PVP
• Poly(ethylenoxide) - PEO
• Poly(acrylic acid) - PAA
• Poly(vinylalkohol) - PVA
• Hydrophilic polyurethanes
• Etc.
Urinary catheters
Guide wires
Heart valves
Contact lenses
Endotracheal tubes
Gastroenteric feed tube
Etc.
Substrate materials
•
•
•
•
•
•
•
•
PVC
Polyurethane
Natural Rubber
Silicone
Polyolefin and Vinyl rubber
Metals
Ceramics
Etc.
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Hydrophilic Coating - Living tissue interaction
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Biopolymers:
• Hyaluronic acid
• Chondroitin sulphate
• Heparin
• CMC
• Etc.
Coloplast “Ready to Use” SpeediCath platform
N
n
O
PVP
+
Photoinitiator
N
n
O
N
O
N
n
O
n
+ Photoinitiator-H
PVP
Hydrophilic coating
cross-linked PVP
Water with 0,9% NaCl and PVP
Catheter wall
Catheter tip
Tube lumen
Catheter eyelets
Swelled
crosslinked
PVP coating
Catheter
SpeediCath “Ready to use” intermittent catheter product range so far:
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Hydrophilic Coating - Living tissue interaction
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Self catheterization with intermittent catheters
Male intermittent catheterization
User groups:
Spinal cord injury (SCI)
Spina Bifida
Multiple Sclerosis (MS)
Stress and/or Urge Incontinence
Lubricious coating facilitates ease of insertion
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Hydrophilic Coating - Living tissue interaction
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Female intermittent catheterization
Characterization of frictional properties of urinary catheters
Friction force tested on fully hydrated coating
using dry silicone gripper pads
Friction force and wear tested in aqueous solution
at constant temperature - mucous membrane or
tissue an option
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Hydrophilic Coating - Living tissue interaction
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In vivo friction test - coating versus living tissue
Configuration of the rabbit urethra and bladder
Size CH8 coated catheter inserted in the rabbit urethra and bladder
Finding the rabbit penis
Histology – cross section of the rabbit urethra
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Hydrophilic Coating - Living tissue interaction
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Friction force against rabbit urethra mucosa
Withdrawal force measured as Static- and Dynamic friction force of coating swelled in sterile water or -saline solution
T-peak
T-peak, Static friction
Dynamic
2
3
2,5
1,5
2
1,5
Dynamic friction
5 minutes
1
15 minutes
0,5
0
-0,5
Sterile water
Water w. 0,9% NaCl
-1
Withdrawal force [mN] of the coating
from the rabbit urethra
Static friction force [N] or adhesion of the coating to rabbit urethra
measured after 5 and 15 minutes of insertion time
1
5 minutes
15 minutes
0,5
0
Sterile water
Water w. 0,9% NaCl
-0,5
Dynamic friction force [N] between coating and rabbit urethra
measured after 5 and 15 minutes of insertion time
Osmolality (osmotic pressure) plays an important role on the withdrawal force
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Hydrophilic Coating - Living tissue interaction
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Osmolarity-driven mass transport of water
Impact on the lubricity and adhesiveness of hydrophilic polymers
Coating swelled in sterile water
Coating swelled in sterile isotonic water, 0.9% NaCl
Hydrophilic coating
Water movement
Mucous membrane of the rabbit urethra
Hydrophilic coating
Water movement
Mucous membrane of the rabbit urethra
The coating system must not dry out during use
The effect of osmolarity on the friction force of a catheter against the urethra mucosa wall is examined in the paper by Lundgren et al. 2001. The importance of osmolality for intermittent catheterization of the urethra; Spinal Cord, 38, pp 45-50
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Hydrophilic Coating - Living tissue interaction
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Lubricity and adhesiveness of hydrophilic polymers depends
on hydration!
The Diffusion-Interpenetration Theory of Mucoadhesion
Commonly used mucoadhesive polymers
Rank order of mucoadhesive force
a. Top layer (Polymer) - Bottom layer mucous membrane before contact
b. Top and bottom layer mucous membrane immediately after contact
c. Top and bottom layer mucous membrane after contact for a period of time
HUANG, Y.; LEOBANDUNG, W.; FOSS, A.; PEPPAS, N.A. Molecular aspects of muco- and bioadhesion: Tetheres
structures and site-specific surfaces. J. Control. Release,v.65, n.1, p.63-71, 2000.
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Hydrophilic Coating - Living tissue interaction
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Chen J, Cyr GN. Compositions producing adhesion through hydration. In: Manly RS, editor.
Adhesion in biological systems. NewYork: Academic;1970. pp. 163–81.
From test in rabbit to validation on humans
Man and machine:
Stensballe J, Looms D, Nielsen PN, Tvede M.: Hydrophilic-coated catheters for intermittent catheterisation reduce urethral micro trauma: a prospective,
randomised, participant-blinded, crossover study of three different types of catheters. Eur Urol. 2005 Dec;48(6):978-83.
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Hydrophilic Coating - Living tissue interaction
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Conclusive remarks
Demonstrated:
• It is possible to design a superior hydrophilic lubricious coating system for intermittent catherization
• The hydrophilic coating is highly affected by osmotic driven water transport in contact with living tissue
 Fully hydrated hydrophilic polymers are extremely lubricious
 Partially hydrated hydrophilic polymers may form a strong mucoadhesive gel
• Preclinical trials are crucial for tailoring polymer systems for high lubricity of intermittent catheters
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Hydrophilic Coating - Living tissue interaction
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