Biomedical Engineering Reference
In-Depth Information
energy occurs between the incident light and the surface plasmon waves.
h e position of the resonance angle is sensitive to the changes in the refrac-
tive index and/or thickness of the layer in the vicinity of metal surface.
When the resonance angle varies in time, we obtain kinetic curve.
h e usage of gold layer as a transducer in the SPR biosensors is very
perspective since it allows obtaining stable and reproducible signal.
Acceptable performance of the sensors requires, even for gold i lms, a pro-
tective coverage to improve the stability of transducer during immersion
in aqueous solutions and smoother surface. Some proteins are dii cult
to attach directly to a metal surface, some of them may denaturate at the
direct adsorbing on such surface [28]. In our investigations we realized a
lot of dif erent methods for biological component immobilization on the
transducer surface [29-31].
13.2.6.1
Estimation of Anti-insulin Ab in Serum Blood [32-34]
Today we know that the presence of Ab against any structures of own
organism shows about the development of autoimmune disorders. h at
is why, the problem of the identii cation of this class of compounds and
their quantitative analysis has important scientii c and practical signii -
cance, because it allows, on the one hand, studying the mechanism of
various pathological forms of pancreatic cancer, knowledge of which will
promote individualization and improve insulin therapy from other one.
h is result should be provided as soon as possible even with very high
sensitivity. h e presence of Ab to insulin may interfere with the determina-
tion of its level in the blood and af ect the outcome of glycemic control in
patients with diabetes. In addition, high levels of Ab against insulin may
contribute to the immune resistance in these patients, requiring the need
for dynamic control of the concentration of this type of Ab in patients with
diabetes who receive various insulin preparations. Especially it should be
noted that in most cases there is a need to use express (sometimes even
result should be obtained immediately), highly sensitive and specii c meth-
ods strictly. Just the last two requirements are met by classical methods
of modern immune-chemical analysis, such as radio-immune (RIA) and
immune-enzyme (the ELISA) methods. h e latter is used for the detection
of Ab to glutamic acid decarboxylase [35]. Its sensitivity reached 20 ng/ml.
However, in both cases the expressivity of the immune-chemical methods
is insui cient. In full it could be really provided only with the immune
biosensors. Early [36] for the detection of auto-Ab to insulin the immune
biosensor based on ellipsometry was developed which has sensitivity in the
range of 10 ng/ml to 100 μg/ml.
