A Compactly Integrated Flow Cell with a Chemiluminescent FIA System for Determining Lactate Concentration in Serum

Abstract

We have fabricated an integrated flow cell as a total microanalysis system (microTAS). This flow cell (size, 15 x 20 mm; total inner volume, 12.2 microL) was designed for a rational analyzing system of lactate determination for serum. This cell was made by micromachining techniques and consisted of two hollows of a lactate oxidase (LOD) reactor and a mixing cell, a spiral groove, and three penetrated holes. To form the reactor and capillary, these patterns, etched on a silicon wafer, were attached to a glass plate by the anodic bonding method. A photodiode was put under part of the spiral capillary. The compactly accumulated devices were integrated into a flow injection analysis (FIA) system. In the flow cell, lactate was catalyzed to pyruvate and hydrogen peroxide at the LOD reactor; subsequently, hydrogen peroxide reacted with the luminol-ferricyanic reagent at the mixing cell. The resulting chemiluminescent light was detected by the photodiode. Using the miniaturized flow cell, the sample volume for one measurement was greatly reduced to 0.2 microL. The response to lactate was obtained within 30 s and was linear between 0.5 and 5.0 mM (4.5 and 45 mg/dL) lactate with excellent correlative variances of 3.2% (average of three measurements at 5.0 mM). For practical application, the lactate concentration in control human serum was determined using this system. The results showed a good correlation coefficient (r = 0.979) with the results obtained by the spectrophotometric reference method. No difference in sera (normal or pathological) was found. Consequently, this integrated flow cell shows potential as a clinical device for lactate determination in serum. In this article, the effect of the design on the chemiluminescent FIA system is also described.

Complexation of L‐Lactate with Boronic Acids: A Solution and Holographic Analysis

“…l-Lactate is a key metabolite, the detection of which is important across a number of disciplines, including clinical diagnostics [10,11] and sports medicine. [12,13] The integration of boronic acids into polymers has been reported previously [14] and more recently a hydrogel was generated that enabled the holographic determination of l-lactate.…”

Peer Reviewed: Analytical Bioluminescence and Chemiluminescence

“…A recently described integrated CL flow cell can measure physiological lactate levels in a 0.2-µL serum sample in <1 min without sample pretreatment (17). All the components-the enzyme reactor with the immobilized lactate oxidase, the cell for mixing the sample and reagents, and the spiral groove for measurementare contained on a 15 ϫ 20 mm silicon chip ( Figure 2).…”

Establishment of Ferricyanide Chronoamperometric Total Antioxidant Capacity Assay Employing a Carbon Screen-Printed Disposable Microchip &mdash;Fundamental Study Using Vegetable Extraction&mdash;

“…(1) For example, lactic acid in serum was determined with a 0.2 μL sample volume and a compactly integrated flow microchip, which was fabricated by micromachining. (2) Further enhancement of the disposability was realized by carbon screen printing onto the surface of a polymer sheet. Using this technique, several types of disposable microchips for electrochemical chronoamperometric sensing employing ferricyanide mediation have been developed for measurements of blood constituents, (3)(4)(5)(6) ethanol in alcoholic beverages, (7) environmental water quality, (8) and for composting.…”