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QCM µLibra microbalance to study the interaction between complementary and not complementary DNA strands
µLibra
employs AT-cut piezoelectric
quartzes as transductor units with 10 MHz fundamental oscillation frequency
that allow the real-time, label-free monitoring of the nucleic acid
hybridization events by means of the oscillation frequency shift. This
frequency shift is due to a mass increase onto quartz surface, generated by
the hybridization between strands. The quartz surfaces is coated by a golden
layer, which represents the electrode.
A thiolated oligonucleotide sequence can be directly adsorbed onto the
electrode surface or by using aminosilane compounds (APTES), with or without
crosslinkers. Moreover, by coating the surface with streptavidin, and
biotinilated-oligonucleotide is possible to obtain very stable complex thanks
to the specific binding streptavidin-biotin (left).
As the quartzes is coated by the probe interacts with the
complementary sequence, eventually, contained in the sample, and their
hybridization (matching) will result in a decrease in the oscillation
frequency (left).
Very interesting is the possibility to individuate mutations inside
the examined sequence, since the lack of hybridization between full
complementary strands (mismatching)
is not able to generate a similar shift.
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DNA Electrochemical sensor
Technobiochip ’s Electrochemical DNA Sensor enables the
monitoring of adsorbed DNA species at carbon electrodes using the
Potentiometric Stripping Analysis (PSA). The DNA binding onto the solid
substrate is mediated by the stable interaction between streptavidin (onto
the electrode) and biotin (oligonucleotide conjugated). The hybridization
event (matching) detection
involves the use of an electroactive indicator, daunomycin hydrocloride,
which intercalates the double stranded DNA. The mismatching between strands,
due to mutations, results in a lack of daunomycin intercalation, and thus to
a lower current signal compared to that generated by the hybrid.
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