Biomedical Engineering Reference
In-Depth Information
140 Å
70 Å
0 Å
12.5
μ
m
Fig. 3.1.4-17 An AFM tip, using relatively high force, was used to scratch a rectangular feature into a thin (70 A
˚
) plasma deposited
film. The AFM could also characterize the feature created.
proven with studies on hydrated hydrogels, polyurethanes,
surface active polymer additives, and proteins (
Shen,
1989
;
Chen
et al.
,2002
).
In Raman spectroscopy a bright light is shined on
a specimen. Most of the light scatters back at the same
frequency as the incident beam. However, a tiny fraction
of this light excites vibrations in the specimen and
thereby loses or gains energy. The frequency shift of the
light corresponds to vibrational bands indicative of the
molecular
structure of
the specimen. The Raman
Table 3.1.4-7 Methods that may have applicability for the surface characterization of biomaterials
Method
Information obtained
Second-harmonic generation (SHG)
Detect submolayer amounts of adsorbate at any light accessible interface
(air-liquid, solid-liquid, solid-gas)
Surface-enhanced Raman spectroscopy (SERS)
High-sensitivity Raman at rough metal interfaces
Ion scattering spectroscopy (ISS)
Elastically reflected ions probe only the outermost atomic layer
Laser desorption mass spectrometry (LDMS)
Mass spectra of adsorbates at surfaces
Matrix assisted laser desorption ionization (MALDI)
Though generally a bulk mass spectrometry method, MALDI has been used
to analyze large adsorbed proteins
IR photoacoustic spectroscopy (IR-PAS)
IR spectra of surfaces with no sample preparation based on wavelength-
dependent thermal response
High-resolution electron energy loss spectroscopy (HREELS)
Vibrational spectroscopy of a highly surface-localized region, under ultrahigh
vacuum
X-ray reflection
Structural information about order at surfaces and interfaces
Neutron reflection
Thickness and refractive index information about interfaces from scattered
neutrons
d
where H and D are used, unique information on interface
organization can be obtained
Extended X-ray absorption fine structure (EXAFS)
Atomic-level chemical and nearest-neighbor (morphological) information
Scanning Auger microprobe (SAM)
Spatially defined Auger analysis at the nanometer scale
Surface plasmon resonance (SPR)
Study aqueous adsorption events in real time by monitoring changes in
surface refractive index
Rutherford backscattering spectroscopy (RBS)
Depth profiling of complex, multiplayer interfacial systems
