Biomedical Engineering – From Theory to Applications

118
Biomedical Engineering – From Theory to Applications
Fig. 19. Electropherograms of (a) human plasma and (b) red blood cell lysate injected across
a 10 nm pore diameter membrane without any off-chip deproteinization procedure. The
separation buffer was 100 mM TBE (pH 8.4). The injection time was 2 s, Vinj = 800 V, Vsep =
1500 V. Reprinted from ref. (Long et al., 2006), with permission.
5.2.2 Analysis of proteins
ITP-ZE. Ölvecká et al. (Ölvecká et al., 2004) demonstrated the potential of their CC chip for
highly sensitive analysis of proteins using the online ITP–ZE combination method. The aim
of the ITP step in this work was restricted mainly to the concentration of proteins before
their ZE separation and conductivity detection. ITP and ZE cooperatively contributed to
low- or sub-μg/mL concentration detectabilities of proteins and their quantitations at 1-5
μg/mL concentrations.
IEF-ZE. A two-dimensional electrophoresis platform, combining isoelectric focusing
(IEF) and zone electrophoresis (ZE), was established on a microchip for the high-throughput
and high-resolution analysis of complex samples (separation of the digests of bovine
serum albimine and proteins extracted from E. coli) (Cong et al., 2008). During the
separation, peptides were first focused by IEF in the first dimensional channel, and then
directly driven into the perpendicular channel by controlling the applied voltages, and
separated by ZE.
ITP-GE. A microchip for online combination of ITP with gel electrophoretic separation was
developed to decrease the detectable concentration of SDS-proteins (Huang et al., 2005).
Without deteriorating the peak resolution, this system provided a 40-fold increase of the
sensitivity, saved analysis time and simplified the instruments for SDS-proteins analysis
when compared to the gel electrophoresis mode (see Fig.20).