Công nghệ vật liệu trong y sinh học biom aterials chapter 2 5

Chap.2. –

2.10. Surface modification of Biomaterials

SOME IMPORTANT MODIFIED SURFACES
1. Anti-fouling (nonfouling) surfaces (NFSs)
- NFSs refer to surfaces that resist the adsorption of protein and/or adhesion of cells (protein-resistant
surfaces and “stealth” surfaces)
- Generally: hydrophilic surfaces are more likely to resist protein adsorption and hydrophobic surfaces
usually will adsorb a monolayer of tightly adsorbed protein
- NFSs are also important to reduce bacterial bio-films forming which can stimulate significant
inflammatory reaction to the infected devices (in urinary catheters and endotracheal tubes, in vascular
grafts, hip joint prostheses, heart valves and other long-term implants)

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- Used as blood-compatible materials (where they may resist fibrinogen adsorption and platelet
attachment), implanted devices, urinary catheters, diagnostic assays biosensors, affinity separations,
microchanel flow devices, intravenous syringes and tubing
(It is important to noted that many of these uses involve in vivo implants or extracorporeal devices,
and many others involve in vitro diagnostic assays, sensors…)
- Examples: Blood compatible “PEO-like” films

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*Usually coated on PET surfaces by plasma deposition

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•Surface containing PEG- poly(ethylene glycol) (-CH2CH2-O-)n

n from 2 to 15: oligome ethylene glycol (oEG)
n from 15-3500 (M = 400- 100,000): PEG
n greater than 100,000: PEO - poly(ethylene oxide)

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Chap.2. – 2.10. Surface modification of Biomaterials

2. “Teflon-like” films

• Used as Blood-compatible materials, usually coated on Dacron

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• Composition: CFx (0function of the composition (F/C ratio), wettability and structure of the film

Schematic diagrams of “Teflon-like) coating: (A) network structure with variable F/C ratio
(2≥F/C>0), and high cross-linking; (B) ordered chain structure with –CF3 surface groups,
high F/C ratio, very low cross-linking and surface energy
*Preparation by RF plasma deposition of C2F4 in H2 , composition is controlled by changing C2H4/H2 feed
* Very hydrophobic, high protein retention
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Chap.2. –

2.10. Surface modification of Biomaterials

3. “Silicone-like” films
• Excellent properties for application in many different fields: optical coating (hardness, resistant to
scratch, adhesion to polymer lenses, proper refraction index), corrosion protection (chemical inertness),
food and pharmaceutical packaging (flexibility, high barrier to O2, H2O vapor and aromas) and others
• Prepared by RF plasma deposition of silicone- containing organic monomers in mixture or not with
other gases (e.g O2), composition SixCyHkOz is variable and is controlled by changing plasma
parameters

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• Used as coating of blood-contacting materials, coating for carbon particles in blood filters and PP
hollow fibers membranes in blood oxygenators (reduce production of thrombi and emboli, reduce

leakage of blood plasma through the membranes as well as decrease release of particles in the blood
stream for coated active carbon)

4. Surface-immobilized biomolecules

*Heparin, heparin-like molecules, collagen, albumin and other biological origin confer anti-thrombotic
properties on polymer surfaces where they are immobilized
polymer need first to be activated,
and the to react with the molecule to be coupled with, directly or through a previously attached “spacing
arm” molecule

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•They and other biomolecules such as enzymes, antibodies, affinity protein, cell receptor ligands, and
drug of all kinds have been chemically or physically immobilized on and within biomaterial supports
• Used for a wide rang of therapeutic, diagnostic, separation and bioprocess applications

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• These “Hybrid combinations” of natural and synthetic materials confer “biological functionality” of
synthetic materials

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Immobilized biomolecules
and their uses

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Immobilized biomolecules
and their uses (cont)

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Immobilized biomolecules

and their uses (cont)

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Methods for Immobilization of biomolecules

- For covalent binding to an inert solid polymer surface, the
surfaces must first be chemically modified to provide
reactive groups (e.g:-OH,-NH2, -SH, -COOH or -CH=CH2

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Methods for Immobilization
of biomolecules

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Methods for Immobilization of biomolecules (cont.)
2.10.
Surface modification of Biomaterials

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