Silicone Biomaterial Recap ƒ Enabled by the intrinsic properties of silicone materials… ƒ … manifest in the aggregated properties of biocompatibility and biodurability,silicone in its 66 th year as a biomaterial ƒSilicone biomaterials can help enable further improvements in medical technology and care

1. Silicone Biomaterial Applications:
Past, Present and Future
jim.curtis@dowcorning.com
Select Examples

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Silicone
Kipping gave us the name “Silicone” based on the similarity of the
organosilcon compounds he developed with ketones.
Generally, we think of silicones as polymers with a backbone of
silicon to oxygen bonds, but other structures such as silicate
resins might also be called silicone.
Si
R
R
O Si
CH3
CH3
O
n
siloxane polydimethylsiloxane
and if R is CH3,
Kipping, FS (1904). Organic derivative of silicon. Preparation of alkylsilicon chlorides. Proc. Chem. Soc. 20, 15.
silicate resin

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Silicone Properties of Interest in Medicine
Thermal stability
Chemical stability
Electrical insulation
High gas permeability
Intriguing surface properties
Low surface tension (20.4 mN/m)*
Critical surface tension of wetting (24 mN/m)
Water repellency
*At the highest molecular weight pdms measured in Roe RJJ (1968)
Phys. Chem., 70, 2013. Owen MJ (1981) Why silicones behave
funny. Chemtech, 11, 288. Colas, André; Curtis, Jim (2004).
Biomaterials Science, Second Edition: An Introduction to Materials in
Medicine. Elsevier, Academic Press.

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Host / Material Interactions
Biodurability:
Host has minimal adverse effect on material
No material is suitable for every application…
…but silicones have a strong history of stability in the body
• PMDS is even added to increase the biodurability of other polymers such
as polyurethane
Biocompatibility:
“The ability of a material to perform with an appropriate host
response in a specific situation”
No material is suitable for every application…
…but silicones are often thought of as intrinsically biocompatible…
… based on a long history of successful use in numerous applications
Black, J. (1992). Biological Performance of Materials: Fundamentals of Biocompatibility. Marcel Dekker, New York.
Remes, A., and Williams, D. F. (1992). Immune response in biocompatibility. Biomaterials, 13(11): 731. Colas, André; Curtis, Jim
(2004). Biomaterials Science, Second Edition: An Introduction to Materials in Medicine. Elsevier, Academic Press
Host
Material

5. Silicone Biomaterial Applications:
Past, Present and Future
Select Examples

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Blood Coagulation Prevention
Silicone’s water repellency caused it to be considered for
prevention of blood coagulation in the 1940s.
Toronto and Manitoba researchers coated syringes, needles, and
vials with methylchlorosilane. When rinsed with distilled water,
the silane hydrolyzed, forming a silicone coating on the glass
and metal substrates which delayed blood clotting.
Mayo Clinic researchers found storage in silicone-coated syringes
did not affect blood coagulation time after being dispensed;
declared silicone was “the most practical of any known
[substance] for coating needle, syringe and tube.”
Silicone precoating of needles, syringes, and blood collection vials
became commonplace and continues today.
Jaques, LB; Fidlar, E; Feldsted, ET; MacDonald, AG (1946). Silicones and blood coagulation. Can. Med. Assoc. J., 55, 26.
Margulies, H; Barker, NW (1949). The coagulation time of blood in silicone tubes. Am. J. Med. Sci., 218, 42.

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Needle Lubrication
Silicone-coated needles penetrate easier.
Today most hypodermic needles, syringes, and other blood-
collecting apparatus are coated or lubricated with silicone.
Silicone coated and non-coated hypodermic needle penetration force s measured by Melab equipment using DIN 13097.
Photo courtesy of Melab GmbH..

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Extracorporeal Equipment
Silicone found application in
extracorporeal machines,
due to their permeability and
hemocompatibility properties.
Cardiac bypass, circa 1964
Silicone’s use in extracorporeal applications continues today.
Hemocompatibility testing has suggested that phthalate-free
silicone tubing may be superior to PVC.
Harmand, MF; Briquet, F (1999). In vitro comparative
evaluation under static conditions of the hemocompatibility of
four types of tubing for cardiopulmonary bypass. Biomaterials
20(17), 1561. AV06443

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Catheters, Drains and Shunts
Silicone elastomers are used in catheters, shunts, and drains.
silicone extrusions
silicone-coating of other materials
Silicone catheters, Drains and Shunts remain in use today.

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catheter
body seal
PSA
trocar
Suprapubic Drainage
Silicone suprapubic catheter sets remain in use today.

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Early Long-Term Implants
The first published report of silicone elastomers being implanted
in humans was in April 1946, when Dr. Frank H. Lahey told of
his use of these materials for bile duct repair.
Dr. DeNicola implanted a silicone artificial urethra in 1948.
Fourteen months after implantation, the artificial urethra “had
been retained with normal genitourinary function.”
Lahey, F. H. (1946). Comments made following the speech “Results
from using Vitallium tubes in biliary surgery,” read by Pearse HE
before the American Surgical Association, Hot Springs, VA. Ann.
Surg., 124, 1027.
DeNicola, R. R. (1950). Permanent artificial (silicone) urethra. J.
Urol., 63(1), 168–172.

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Hydrocephalus Shunt
1956 John Holter & son “Casey”
Dr. Eugene Spitz identified need:
Competent one-way valve that
…could be sterilized &
… remained stable in vivo
Holter developed it in his garage
using silicone rubber and tubing
provided free from Dow Corning
Baru, J. S., Bloom, D. A., Muraszko, K., and Koop, C. E.
(2001). John Holter’s shunt. J. Am. Coll. Surgeons, 192, 79.

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Hydrocephalus Shunt
Holter & Spitz patented the design; it was
commercialized by the Holter Company
1957 Reader’s Digest article regarding the
Holter shunt spurred interest in silicone for
medical applications
Holter-designed valves remain available
through Codman and Sophysa
Baru JS, Bloom DA, Muraszko K, Koop CE (2001).
John Holter’s shunt. J Am Coll Surgeons, 192, 79.
LaFay, H. (1957). A father’s last-chance invention
saves his son. Reader’s Digest, January, p 29–32.
Modern hydrocephalus shunts and valves continue to use silicone.
Modern Codman Hakim programmable valve shunt. Courtesy of Codman, a Johnson & Johnson company

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Center for Aid to Medical Research
1959 Dow Corning Center for Aid to Medical Research
Free clearing house for information & material samples
Corresponded with > 35,000 medical professionals
Braley, S. A. (1973). Spare Parts for Your Body. Dow Corning Center for Aid to Medical Research, Midland, MI.

15. Artificial Organs
15
Dr. Michael E. DeBakey

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Dedicated Production Site
1963 Dow Corning built a production plant dedicated to medical
products featuring: rural location, positive pressure, ultraclean
practices, biological surveillance, and lot traceability

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Cardiac Valves
Blood compatibility was a factor in the application of silicone in
several mechanical heart valves
Silicone heart values remain in use today
Bhat SV. (2002) Biomaterials. Springer pp. 69.

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Implantable Pacemakers
Silicone was used in early pacemaker implants
encapsulated the electronic components and “can”
insulated the leads
enabled waterproof connection
Colas, André; Curtis, Jim (2004). Biomaterials Science,
Second Edition: An Introduction to Materials in Medicine.
Elsevier, Academic Press,
Silicone remains in use in today’s modern pacemakers and leads.

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Orthopedic Implants
Silicone small joint implants
Swanson, A. B. (1968). Silicone rubber implants for replacement of arthritic or destroyed joints in the hand. Surg. Clin. North Am., 48, 1113.
Silicone small joint implants remain available today.

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Orthopedic Implants
Cement restrictors
Silicone bone plugs remain available today.

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Aesthetic Implants
Silicone use in aesthetic and reconstructive implants
Over 40 years
Breast, Scrotum, Chin, Nose, Cheek, Calf, Buttocks
Cronin design mammary prosthesis, 1964 Silicone testicular implants
Silicone breast implants are available today; silicone gel testicular implants are not generally available in the USA
Cronin TD, Gerow FJ. (1963). Augmentation mammaplasty: a new
“natural feel” prosthesis. Transactions of the Third International
Congress of Plastic Surgery—Excerpta Medica, Int. Congr. Ser., 66, 41.

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Other Silicone Implants/Devices
Silicone has been used in several other implants or devices
Head
Burr-hole covers
Surgical products for treatment of retinal detachment
Intraocular lenses (foldable)
TMJ implants
Cochlear implants
Dental impression materials
Breathing masks
Nasogastric feeding tubes
Braley, S. A. (1973). Spare Parts for Your Body. Dow Corning
Center for Aid to Medical Research, Midland, MI. Colas, André;
Curtis, Jim (2004). Biomaterials Science, Second Edition: An
Introduction to Materials in Medicine. Elsevier, Academic Press
These silicone devices remain available today with the exception of silicone TMJ implants, which are not.

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Other Silicone Implants/Devices
Silicone has been used in several other implants or devices
Neck
Tracheostomy tubes
Artificial Larynx
Urogenital
Slings (urinary incontinence)
Pessaries (incontinence, reconstruction)
Penile Implants (impotence)
Vaginal rings (drug delivery)
These remain available today.
Braley, S. A. (1973). Spare Parts for Your Body. Dow Corning
Center for Aid to Medical Research, Midland, MI. Colas, André;
Curtis, Jim (2004). Biomaterials Science, Second Edition: An
Introduction to Materials in Medicine. Elsevier, Academic Press

24. Silicone Biomaterial Applications:
Past, Present and Future
Select Examples

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Wound Care
Courtesy of Beiersdorf AG

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Contact Lenses
Silicone-Hydrogel
Lens Dk increases with silicone content
Approved for 30 days of continuous wear
Fewer complications, more comfort
Dillehay, S. M. (2007). Does the level of available oxygen
impact comfort in contact lens wear?: A review of the
literature. Eye Contact Lens, 33(3), 148-55.

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Gastric Bands
Silicone elastomer is used in the bariatric implants:
Lap-Band® (Allergan)
Realize® (Ethicon Endo-Surgery, J&J)
BMI > 40 or Weight >45 kg above ideal
In 2011, FDA allowed expanded indication
BMI > 30…
…plus diabetes or hypertension
US FDA P000008 Lap-Band, P070009 Realize. Gastroenterology and Urology Devices Panel, December 3, 2010

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Drug Delivery Applications
Silicone PSA in TDDS patches
Controlled release
Compliance
Rivastigmine for Alzheimer’s (Exelon®)
Methylphenidate for ADHD (Daytrana®)
Nicotine

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Single-use Fluid Transport Systems in
Pharmaceutical Manufacture
FDA emphasis on process validation
Ease of use, connect/disconnection
Well-characterized low extractables profile

30. Silicone Biomaterial Applications:
Past, Present and Future
Select Examples

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Megatrends in Medicine
Geo-expansion to emerging economies
Personalized medicine
Aging populations
Rising healthcare costs
Global pandemics
Environmental concerns
Evidence-based medicine
Shortage of medical doctors
Payer’s influence on care
Prevention
Harvard Business Review Special Report 2010.

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Diagnostic Devices
Lab-on-a-chip & biosensors using
Microfluidics
3-D photolithography
Printable electronics
“Wearable” electronics
Megatrends affected:
Personalized Medicine
Rising costs
Aging Populations
Global Pandemics
Environmental concerns
Second annual Lab-On-A-Chip World Congress,
2010, San Diego.

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Tissue Engineering
Elastomeric scaffolds
Biocompatible constructs
Progenitor cell “training”
Prevention
Healthcare-associated Infection
Anti-infective materials in catheters and other devices
Physical protection for the frail & elderly
Combination products with active-loading to provide benefit
Bettinger, CJ. Synthesis and microfabrication of elastomeric biomaterials for advanced tissue engineering scaffolds .
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.

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Silicone Biomaterial Recap
Enabled by the intrinsic properties of silicone materials…
… manifest in the aggregated properties of biocompatibility and
biodurability,
silicone in its 66th year as a biomaterial
Silicone biomaterials can help enable further improvements in
medical technology and care

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Our Continuing Commitment to Healthcare
Dow Corning has been supplying silicone materials for short- and
long-term implants for many decades
We continue to supply these and develop new innovative products
We operate under indemnification contracts for applications of over
29 days implantation to supply large OEMs and their fabricators
We do not supply applications where our silicone is the active
ingredient for contraception. We will supply for contraception where
the silicone is an excipient, but under indemnification agreements.
We do not sell silicone fluid for cosmetic injection or any other
regulatory-excluded application

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Dow Corning is …..
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A global leader in silicones and high purity
silicon
More than 7,000 products/services
Approx 25,000 customers
Approx 12,000 employees
Strong and healthy financially: $6.43 billion
sales in 2011
Investing in our future and our customers’ futures:
geographic, manufacturing, innovation
Transforming our business to deliver:
Efficiency, Innovation and Sustainability
Focused on sustainability and Responsible Care®
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Dow Corning is a registered trademark of Dow Corning Corporation
We help you invent the future is a trademark of Dow Corning Corporation
Daytrana is a registered trademark of Noven Therapeutics, LLC
Exelon is a registered trademark of Novartis AG
Lap-Band is a registered trademark of Allergan, Inc.
Realize is a registered trademark of Johnson & Johnson Corporation
Thank you for your attention