Lab-on-a-chip for analysis of triglycerides based on a replaceable enzyme carrier using magnetic beads

In this paper an enzyme-carrier-based microfluidic chip coupled with a gold nanoband microelectrode as electrochemical detector for Triglyceride (TG) determination was developed by co-immobilized lipase, Glycerokinase (GK) and glycerol-3-phosphate oxidase (GPOx) on chitosan/Fe(3)O(4) composite nanoparticles with a shell-core structure, which combined the advantageous features of microfluidic chips technology with magnetic beads. This procedure enabled the easy renewal of the microchip enzyme carrier after each determination in a highly reproducible manner. Several operational parameters such as working potential, buffer pH, adenosine triphosphate concentrations (ATP, mM), separation voltage and temperature were evaluated and optimized. The performance of enzyme-carrier-based microfluidic chip for TG determination was modulated by changing the length of enzyme carrier from 1.0 to 3.0 cm, and the linear ranges were changed from 0-4.0 mM to 0-10.0 mM with the detection limits from 15 mu M to 6.0 mu M. The enzyme carrier remained its 70% activity after 40 days storage. This system was successfully employed for on-line detection of TG in serums. The experimental results demonstrated that this enzyme carrier using magnetic beads based microfluidic chip provided a relatively simple, sensitive, miniature, and replaceable means for the accurate determination of TG in serum.