3.1. Quartz crystal microbalance (QCM) aptasensor for detection
of Brucella melitensis
QCM sensors are composed of a thin
piezoelectric plate with two metal electrodes on
either
side (Singh et al., 2013). These sensors
are coated with immobilized bioreceptors such as aptamer (short
synthetic oligonucleotide sequences of single stranded DNA or RNA with
unique 3D structures; aptamer-based biosensors are called aptasensors)
or antibody molecules for the target bacterium on their surface. Hence,
QCM is a sensitive method which is performed
based on the measurement of mass
changes on quartz crystal surface
(Bayramoglu, Ozalp, Oztekin, & Arica,
2019; Urmann, Modrejewski, Scheper, &
Walter, 2016).
As shown in figure 4, Bayramoglu et al. designed a novel quartz crystal
microbalance (QCM) aptasensor for the detection of Brucella
melitensis (Bayramoglu et al.,
2019). In this method, the surface of the magnetic nanoparticles
was modified by 3-aminopropyltriethoxysilane (APTES) and then grafted
with a hydrophilic macromonomer poly(ethyleneglycol)-methacrylate
(PEG-MA) and glycidylmethacrylate (GMA). The specific aptamer sequence
was also immobilized on the QCM chip and utilized for the identification
of B. melitensis (Bayramoglu et al.,
2019).