Faculty: Dr. H. Sheardown

 

 

Dr. Sheardown Professor
Department of Chemical Engineering

McMaster University
1280 Main Street West, Hamilton
Ontario, Canada  L8S 4L7

office: JHE-124A
email: sheardow@mcmaster.ca
voice:  (905) 525-9140 ext.24794

 

B.Eng. McMaster University (1989), Ph.D. University of Toronto (1995).

20/20 NSERC OPHTHALMIC MATERIALS NETWORK

Research Projects

The focus of the work in our lab is the development of novel polymeric biomaterials and novel surfaces for biomedical applications including the delivery of drugs as well as on understanding and manipulating the interactions of these materials and surfaces with the surrounding cells and proteins. Chemical and biological modification techniques are used to improve the interactions between the materials and the surrounding biological environment. The research is focused on two different areas – materials for ophthalmic applications and materials for cardiovascular applications. The research is highly multidisciplinary and we collaborate with other scientists as well as a number of companies. Specific representative projects are described below.

1. Artificial Corneas and Corneal Onlays for Restoration of Sight

Corneal blindness, a condition that affects millions of patients worldwide, is often treatable by replacing the diseased cornea with a human donor. However, the number of patients of waiting lists has grown dramatically in recent years; many other patients are unsuitable for this treatment or simply do not have donor tissue available. Additionally, the safety of donor tissue is always a consideration. We are currently working on two different models with the ultimate goal of developing an implantable corneal model which can be used either as an artificial cornea or which can be used as a corneal onlay. In one project, synthetic polymers are being used as scaffold materials with the application of appropriate modifications to promote interactions with corneal cells. The second project is focused on a tissue engineered cornea which is based on collagen, the natural polymer that provides the structural component of the normal human cornea.

2. Drug Delivery to the Eye

While delivery of drugs to the front of the eye is usually quite easily accomplished through the use of drops, delivery of drugs to the back of the eye for the treatment of a variety of debilitating diseases including Age Related Macular Degeneration (AMD) and diabetic retinopathy is complicated by ocular anatomy and physiology. We are looking a various strategies for the targeted delivery of relevant drugs to the appropriate ocular tissues. In one project we are using alginate microspheres for the release of protein drugs. Another project is focused on the use of a MEMs based system for targeted and controlled ophthalmic drug release.

3. Modification of Intraocular Lenses for Reduction of Posterior Capsule Opacification

Loss of transparency of the lens or cataract is the leading cause of blindness in the world despite the availability of effective surgery. Secondary cataract or posterior capsule opacification (PCO) is the major complication of modern cataract surgery, occurring in between 20 and 40% of patients. This collaborative project is focused on using the ocular signaling molecules involved in PCO formation in conjunction with lens materials to develop novel intraocular lenses which show lower amounts of PCO.

4. Surface Modified Polymers to Minimize Fouling

Protein fouling is a major cause of complications in numerous biomaterials applications. In the eye, contact lens fouling results in discomfort and end of dryness; in the blood contacting applications, protein fouling and resultant effects lead to thrombus formation which can ultimately occlude the vessel or lead to subsequent deleterious cardiovascular effects. These projects involve the modification of various polymer surfaces with low fouling materials such as poly (ethylene oxide) and phospholipids as well as subsequent functionalization with biologically relevant molecules including heparin and cell adhesion

.Books authored

 Proteins cells and materials: the contributions of John Brash. H. Sheardown and S. Cooper (eds). Brill Academic Publishers (2003).

Publications (last 5 years)

Wells L, Sheardown H. Extended release of high pI proteins from alginate microspheres via a novel encapsulation technique. Eur J Pharm In press 2006

Duan X, Sheardown H. Incorporation of cell adhesion peptides into collagen scaffolds promotes corneal epithelial stratification. J Biomater Sci Polym Edn (In press 2006.

Klenkler B.J., Sheardown H. Characterization of EGF coupling to aminated silicone rubber surfaces. Biotech Bioeng 95: 1158-1166 (2006)
.
Duan X, McLaughlin C, Griffith M, Sheardown H. Biofunctionalization of collagen for improved tissue response: scaffolds for artificial cornea. Biomaterials 28: 78-88 (2007)

Friedlaender MH, Breshears D, Amoozgar B, Sheardown H, Senchyna M. The dilution of benzalkonium chloride (BAK) in the tear film. Advances in Therapy. 23: 835-841 (2006)
.
Tun Z, Unsworth LD, Brash JL, Sheardown H. Determination of graft density of substrate supported polymer films. Physica B. 385-386: 697-699 (2006)
.
Chen H., Brook M.A., Sheardown H. Cell interactions with PDMS surfaces modified with cell adhesion peptides using a generic method. Materials Science Forum. 539-543: 705-709 (2006)

Subbaraman L., Glasier M.A., Senchyna M., Sheardown H., Jones L.W. Kinetics of in vitro lysozyme deposition on silicone hydrogel, FDA group II and FDA group IV contact lens materials. Curr Eye Res 31: 787-796 (2006)

Duan X, McLaughlin C, Griffith M, Sheardown H. Biofunctionalization of collagen for improved tissue response: scaffolds for artificial cornea. Biomaterials 28: 78-88 (2007)

Subbaraman L, Glasier M, Sheardown H, Senchyna M, Jones L. Rewetting drops containing surface active agents improve the clinical performance of silicone hydrogel contact lenses. Optom Vis Sci 83: 143-151 (2006)

Duan X., Sheardown H. Dendrimer crosslinked collagen as a corneal tissue engineering scaffold: mechanical properties and corneal epithelial cell interactions. Biomaterials 27: 4608-4617 (2006)

Unsworth L.D., Tun Z., Sheardown H., Brash J.L. In situ neutron reflectometry investigation of gold-chemisorbed PEO layers of varying chain density: relationship of layer structure to protein resistance. J Coll Inter Sci. 296: 520-526 (2005)

Chen H, Brook MA, Sheardown H, Chen Y, Klenkler B. Generic bioaffinity surfaces. Bioconj Chem 17: 21-28 (2006)

Duan X., Klenkler BJ, Sheardown H. Progress in the development of a corneal replacement: keratoprostheses and tissue engineered corneas. Expert Rev Med Dev 3: 59-72 (2006)

Duan X., Sheardown H. Crosslinking of collagen with dendrimers. J Biomed Mater Res 75A: (3): 510-518 (2005)

Mequanint K., Sheardown H. 2-Methacryloyloxyethyl N-butylcarbamate: A new comonomer for hydrogel syntheses with improved hydrophilicity and mechanical properties for ophthalmic applications. J. Biomater Sci Polym Edn. 16: 1303-1318 (2005)

Unsworth L.D., Sheardown H., Brash J.L. Effect of chain density, chain length and end group chemistry of poly(ethylene oxide)-thiol thin films adsorption evaluated using immunoblots and Vroman type experiments. Biomaterials 26: 5927-5933 (2005)

Chen H., Chen Y., Sheardown H., Brook M.A. Immobilization of heparin on a silicone surface through a PEG spacer. Biomaterials. 26: 7418-7424 (2005)

Suuronen E.J., Sheardown H., Newman K., McLaughlin C.R., Griffith M. Building in vitro models of organs. Intl Rev Cytol. 244: 139-175 (2005)

Unsworth L.D., Sheardown H., Brash J.L. Protein resistance of surfaces prepared by sorption of end thiolated poly (ethylene glycol) to gold: Effect of surface chain density. Langmuir 21: 1036-1041 (2005)

Klenkler B.J., Griffith M., Beceril C., West-Mays J., Sheardown H. EGF grafted surfaces in artificial corneal applications. Biomaterials. 26:7286-7296 (2005)

Chen H., Zhang Z., Chen Y., Brook M.A., Sheardown H. Protein repellant silicone surfaces by covalent immobilization of poly (ethylene oxide). Biomaterials. 26: 2391-2399 (2005)

Chen H., Brook M.A., Chen Y., Sheardown H. Surface properties of PEO silicone composites: controlling protein adsorption. J Biomater Sci Polym Edn 16:531-538 (2005)

Unsworth L.D., Tun Z., Sheardown H., Brash J.L. Chemisorption of thiolated poly (ethylene oxide) to gold: surface chain densities measured by ellipsometry and neutron reflectometry. J Colloid Inter Sci 281: 112-121 (2005)

.Chen H., Zhang Z., Chen Y., Brook M.A., Sheardown H. Protein repellant silicone surfaces by covalent immobilization of poly (ethylene oxide). Biomaterials. 26: 2391-2399 (2004)

Liu L., Sheardown H. Polydimethylsiloxane poly (N-isopropyl acrylamide) network polymers as ophthalmic biomaterials. Biomaterials 26: 233-244 (2005)

Ragheb A. Chen H. Marshall M.L. Hrynyk M., Sheardown H. and Brook M.A. Controlling protein deposition at silicone elastomer interfaces. American Chemical Society Division of Polymer Chemistry. U423 (2004)

King M. Duan X, Sheardown H. Modified dendrimers for hydrophobic toxin removal Biotech Bioeng. 86: 512-519 (2004)

Li F., Griffith M., Lohmann C., Li C., Tanodekaew S., Sheardown H., Hakim M., Carlsson D.J. Preparation and characterization of bio-synthetic polymer matrices to promote recruitment of multiple cell lines: functional corneal regeneration. Biomaterials. 26: 3093-3401 (2005)

Klenkler B.J., Sheardown H. Growth factors in the anterior segment: role in tissue maintenance, wound healing and ocular pathology. Exp Eye Res 79: 677-688 (2004)

Unsworth L.D., Tun Z., Sheardown H., Brash J.L. Chemisorption of thiolated poly (ethylene oxide) to gold: surface chain densities measured by ellipsometry and neutron reflectometry. J Colloid Inter Sci 281: 112-121 (2005)

Chen H., Brook M.A. Sheardown H. Silicone elastomers for reduced protein adsorption. Biomaterials. 25: 2273-2282 (2004)

Li F., Carlsson D.J., Lohmann C.P. Suuronen E.J., Vascotto S.G., Kobuch K., Sheardown H.D. Munger R., Nakamura M. and Griffith M., Cellular and nerve regeneration within a bio-synthetic extracellular matrix for corneal transplantation. Proc Natl Acad Sci U.S.A. 100: 15346-15351 (2003)

1Merrett K., Griffith C.M., Deslandes Y., Pleizier G., Dubé M.A. and Sheardown H. Interactions of corneal cells with TGF-?2 modified silicone rubber surfaces J Biomed Mater Res. 67A: 981-993 (2003)

Griffith M., Hakim M., Shimmura S., Watsky M.A., Li F., Carlsson D., Nakamura M., Suuronen E., Shinozaki N., Nakata K., and Sheardown H. Artificial corneas: scaffolds for transplantation and host regeneration. Cornea 21: S54-S61 (2002)

Duan X., Griffith C.M., Dubé M.A. and Sheardown H. Novel dendrimer based polyurethanes for PEO incorporation. J. Biomater. Sci. Polym. Edn. 13:667-690 (2002)|

Merrett K., Cornelius R.M., McClung W.G., Unsworth L.D. and Sheardown H. Surface analysis methods for characterizing polymeric biomaterials. J. Biomater. Sci. Polym. Edn, 13: 593-622 (2002)

Aucoin L., Griffith C.M., Deslandes Y., Pleizier G., and Sheardown H. Interactions of corneal epithelial cells with cell adhesion peptide combinations on PDMS surfaces J. Biomater. Sci. Polym. Edn. 13: 447-462 (2002)

McCormick H., McMillan R., Merrett K., Bensebaa F., Deslandes Y., Sheardown H. XPS and water contact angle evaluation of the effect of conditions of peptide chemisorption to gold and silver coated polymer surfaces Colloids and Surfaces B: Biointerfaces. 26: 351-363 (2002)

Merrett K., Griffith C.M., Deslandes Y., Pleizier G. and Sheardown H. Adhesion of corneal epithelial cells to cell adhesion peptide modified pHEMA surfaces. J. Biomater. Sci. Polym. Edn. 12(6) 647-671 (2001)

Woods D.R.. Kourti T., Wood P.E., Sheardown H., Crowe C.M., Dickson J.M. Assessing problem solving skills II Chem. Eng. Education 36(1) 60-67 (2002
.
Woods D.R., Wood P.E., Sheardown H. and Kourti T. Assessing problem solving skills Chem Eng Education 35(4) 300-307 (2001)

McMillan R., Meeks B., Bensebaa F., Deslandes Y., and Sheardown H. Cell adhesion peptide modification of gold coated polyurethanes for vascular endothelial cell adhesion. J Biomed Mater Res 54: 272-283 (2001)