A Journey into Surface Science and the Groundbreaking 1987 Symposium That Revolutionized Medical Implants
June 21-24, 1987 Ann Arbor, Michigan
Surface analysis techniques for biomaterials and their biological interactions
Imagine a world where a heart valve can seamlessly integrate with your tissue, a dental implant fuses perfectly with your jawbone, or a contact lens moves comfortably across your eye without irritation. What makes these medical marvels possible? The answer lies not in the bulk materials themselves, but in their exquisite surface properties—a fascinating realm where materials science meets biology at the molecular level.
In June 1987, a group of brilliant scientists gathered in Ann Arbor, Michigan, for a groundbreaking symposium that would shape the future of medical implants and devices. Their focus: understanding and controlling the surface characteristics of biomaterials. This conference, officially titled the "Symposium on Surface Analysis of Biomaterials," addressed a crucial challenge—how to create materials that the human body would accept rather than reject 1 . Nearly four decades later, the insights from this meeting continue to resonate through every modern medical device that interacts with our biological systems.
When engineers first developed biomaterials, they focused primarily on bulk properties—strength, flexibility, and durability. But they soon discovered that biological systems don't care what a material is like deep inside—they only interact with its outermost atomic layers. This surface, barely a few nanometers thick, serves as the material's "handshake" with the biological world 2 .
At the surface level, materials can behave completely differently than their bulk counterparts. Composition, microstructure, chemical bonding, and even electronic states can vary significantly from what we find inside the material.
Before the 1980s, studying these surface properties was like trying to map a coastline from an airplane—scientists could only get crude, indirect measurements. The Ann Arbor symposium showcased revolutionary techniques that allowed researchers to "zoom in" to the molecular level 2 :
Electron Spectroscopy for Chemical Analysis
Uses X-rays to eject electrons from atoms, revealing both elemental composition and chemical state of surface atoms 3 .
Auger Electron Spectroscopy
Uses electron beams to excite atoms, causing them to emit characteristic electrons that identify surface elements.
Secondary Ion Mass Spectrometry
Bombards the surface with ions and analyzes the ejected secondary ions to determine surface composition.
One of the most exciting discussions at the symposium revolved around angular-dependent ESCA—a sophisticated variation of electron spectroscopy that provides depth-resolution information without physically sectioning the sample 3 .
The sample is irradiated with X-rays, causing electrons to be ejected from atoms in the surface region.
A spectrometer measures the kinetic energy of these ejected electrons, which reveals their elemental identity and chemical environment.
By varying the angle between the sample surface and the detector, scientists can control the effective sampling depth. Shallow angles primarily detect electrons from the outermost surface, while steeper angles probe deeper layers.
Angular-dependent ESCA allows non-destructive depth profiling of the top 5-10 nm of a material's surface.
One of the landmark studies presented at the symposium focused on polymer-coated glass surfaces designed as substrates for tissue culture. The critical question: How do surface chemical properties affect cell attachment and growth?
Glass slides were coated with various polymers using different application techniques to create surfaces with varying chemical functionalities.
The characterized surfaces were then used in cell culture experiments to correlate surface chemistry with biological response.
The ESCA analysis revealed dramatic differences between surfaces that appeared identical under conventional microscopy:
| Sample ID | % Carbon | % Oxygen | % Nitrogen | Dominant Carbon Species |
|---|---|---|---|---|
| A | 72.3 | 24.1 | 3.6 | C-C (hydrocarbon) |
| B | 64.8 | 32.4 | 2.8 | C-O (ether/alcohol) |
| C | 59.1 | 35.2 | 5.7 | C=O (carbonyl) |
| D | 68.5 | 27.9 | 3.6 | Mixed environment |
The subsequent biological testing showed that Sample C, with its higher concentration of polar carbonyl groups, supported significantly better cell attachment and growth than the other surfaces. This finding demonstrated conclusively that specific chemical functionalities could enhance biological integration—a fundamental insight that would guide biomaterial development for decades to come 3 .
The angular-dependent studies provided even deeper insights:
| Detection Angle | % C=O | % C-O | % C-C | Conclusion |
|---|---|---|---|---|
| 15° (surface-sensitive) | 42.3 | 38.1 | 19.6 | Carbon-rich surface layer |
| 45° (intermediate) | 38.7 | 36.9 | 24.4 | Gradual transition |
| 90° (bulk-sensitive) | 31.2 | 41.8 | 27.0 | More oxygenated subsurface |
The symposium highlighted several essential materials and reagents that enabled these surface characterization advances:
| Reagent/Material | Primary Function | Significance in Research |
|---|---|---|
| Ultra-pure solvents | Sample cleaning and preparation | Prevent surface contamination that could skew analysis results |
| Standard reference materials | Instrument calibration | Ensure accurate quantification of surface elements |
| Monochromatic X-ray sources | High-resolution ESCA | Provide precise energy resolution for chemical state identification |
| Electron flood guns | Charge compensation | Prevent buildup of electrical charge on insulating samples |
| Ultra-high vacuum systems | Maintain surface purity | Preserve sample integrity during analysis |
| Certified purity gases | Surface modification | Create controlled chemical changes for functionalization studies |
| 1-Methylpyrrolidine | 120-94-5 | C5H11N |
| Flurbiprofen axetil | 91503-79-6 | C19H19FO4 |
| Fluticasone furoate | 397864-44-7 | C27H29F3O6S |
| Ketoprofen lysinate | 57469-78-0 | C22H28N2O5 |
| 2-Bromobenzaldehyde | 6630-33-7 | C7H5BrO |
The 1987 Symposium on Surface Analysis of Biomaterials produced insights that reverberate through modern medicine. Today's medical implants—from coronary stents to artificial hips—benefit directly from the foundational work presented in Ann Arbor.
Surface composition differs from bulk composition—often dramatically, requiring specialized analysis techniques.
Tiny variations in surface chemistry can determine biological success or failure of implants.
Sophisticated surface analysis is essential for biomaterial development and quality control.
Collaboration between materials scientists, chemists, and biologists is crucial for progress.
The proceedings from this symposium, edited by Buddy D. Ratner, became a seminal reference that guided a generation of biomaterials researchers 1 . The meeting also fostered ongoing collaborations that would advance surface analysis techniques, making them more sensitive, more quantitative, and more applicable to complex biological interfaces.
As we look toward the future of biomaterials—with smart implants that can monitor their environment, tissue-engineered constructs that can regenerate damaged organs, and nanoscale devices that can deliver drugs with precision—we build upon the foundation established at gatherings like the 1987 symposium. The invisible world where materials meet biology continues to be one of the most fertile frontiers for medical advancement, proving that sometimes, the most important things really do happen on the surface.
This article is based on the proceedings of the Symposium on Surface Analysis of Biomaterials held in Ann Arbor, Michigan, June 21-24, 1987, as documented in "Surface Characterization of Biomaterials" edited by B.D. Ratner 1 .