Biomedical Engineering Reference
In-Depth Information
Practically, analytical measurement of the oxygen level can be per-
formed via different standard analytical methods, either directly or
indirectly, using conventional laboratory techniques, optical spec-
troscopy, or the use of a commercially available portable oxygen
meter.
In the conventional method, microspheres will be placed in dry
or incubated in a solution inside an airtight reaction vessel having
an outlet that is connected with tubing. The other end of the tubing
will be inserted into a burette inlet that is first filled with water and
placed backward in a water reservoir. The oxygen produced from
the microspheres will replace the water inside the burette, and the
amount can be recorded directly from the granulated marks on the
burette. This method is simple and cheap but is, however, subjected
with higher errors and lower accuracy. It will be also problematic
if the amount of oxygen produced is too low and insignificant in
causing any water replacement. More fine and small-scaled appara-
tuses will be required when dealing with a low oxygen production
rate.
Another option for a simple, sensitive, and accurate measure-
ment will be via the use of standard optical spectroscopy. ORMs
can be incubated in an airtight standard cuvette containing a solu-
tion with a fluorescent dye that is sensitive to oxygen quenching,
suchasrutheniumcomplexes
74
,
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orerythrosinB.
76
Undercontinu-
ous monitoring using a spectrofluorometer, the decrease of fluores-
cent intensity upon being quenched by the oxygen produced will be
recorded. The quantitative value on the oxygen concentration can
be derived from a calibration curve obtained using various suitable
quenchingmodels.
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Measurementsrecordedusingthismethodare
veryreliablebutrequirehandlingbytrainedpersonalandtheuseof
expensiveoptical instrumentation.
Asimplifiedversionofthespectroscopymethodwillbetheuseof
commerciallyavailableoxygensensors.Thesesensorsareverycom-
mon nowadays and can be purchased easily at a comparatively low
price. Oxygen concentration is recorded directly without the need
of conversion, no calibration curve, and no extra chemical. The han-
dling of such sensors is also often simple, and effort is only needed
on setting up a controlled study with a good plan that can evaluate
the oxygen-releasing profile for the ORMs.
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