Biomedical Engineering Reference
In-Depth Information
Fig. 5
ATR-FTIR measurement of bovine serum albumin [BSA] adsorption on modified
PEU surfaces.
A
AT R- F T I R sp e c t r a a n d
B
quantitative profiles of BSA adsorption on PEU
surfaces modified by MPEO-derived SMAs [81]. Reproduced from [177]
The result recalls the desired functioning of MPEO-derived surface modi-
fying machinery. Compared to non-spacer-tethering immobilization, longer
spacer arms are capable of offering greater freeness for the conjugated lig-
ands to retain better bio-functional efficacies, until an optimal proportioning
between (PEG) spacer length and endgroup species is made. Beyond this
proportional threshold, further longer spacers can hardly provide any more
positive contributions; on the contrary, the negative effect grows due to the
dilution of the endgroup functionalities. The optimal threshold is largely
determined by the intrinsic properties of the endgroup ligands, including
the physicochemical shape, size, hydrophobicity, as well as relevant bio-
chemical traits. Another important recollection is that the unloaded spacer
arms—without functional endgroups, like those on blank MPEO-templates
[MPEO-OH], barely function for repulsing any potential adhesion in a non-
specific manner so that the BSA binding performance is even weaker than
the un-modified PEU surface. Combining these two recollections, the coordi-
nation between spacer arms and functional endgroups, as the major feature
of MPEO-derived SMAs, is again emphasized and highlighted when pursuing
desired bio-functionalities [80, 81].
Radioiodine-Labeling Assessment
The radioiodine (usually radioactive isotope
125
I, marked as I
∗
)-labeling tech-
nique facilitates protein adsorption assessment with sensitivity and speci-
ficity [170], and thereby is employed for evaluations of BSA-vs-Fg binary
binding competition as well as reversibility of BSA adsorption. The labeling
assessment is capable of identifying and monitoring trace amounts of marked
samples from a multi-species system. The labeling methodology is based on
radioiodization of target proteins (BSA and/or Fg), which is conducted via
a reaction between radioiodine and proteinic tyrosine residues. The radioio-
dinated proteins (BSA
∗
and/or Fg
∗
) are used for adsorption trials and the
binding quantities are measured with a
γ
-radiation counter.
