Topics in Current Chemistry (2020) 378:13
1 3
PCR quantification [153], multiple PCR assays [154], and clinical diagnosis [153,
155].
Another probe is the TaqMan assay, which is used to quantify mRNA levels of
selected genes. Two fluorescent moieties with different wavelength emissions appear
in the system. Some recent reports have included the use of MNPs as platforms for
TaqMan probes. For example, Liu et al. described a portable quantitative and selective DNA detection biosensor. In only one step, target recognition occurs as a consequence of the releasing of the invertase–DNA conjugate which can be collected with
the help of a magnet. The released invertase–DNA was used to catalyze the hydrolysis of sucrose into glucose with highly efficient sequence selectivity [156].
DNA-assembled core–satellite superstructures are other platforms used in drug
delivery, imaging, and biosensing. Tian et al. reported an on-particle rolling circle
amplification process [157] that allows rapid microRNA detection. Once the targeted microRNA is detected, the long ssDNA produced acts as the scaffold of the
core–satellite superstructure and it can be hydrolyzed by duplex-specific nuclease.
Due to hydrolyzation, MNPs are released and subsequently quantified in an optomagnetic sensor. The high capacity to discriminate single-nucleotide mismatches
opens new possibilities to use these structures in clinical applications.
The development of nanotechnology and its applications in the field of biotechnology lead to an improvement in bioanalysis. The bar-code analysis, which involves
the use of IONPs and gold nanoparticles, is a diagnostic tool used for the detection of nucleic acids and proteins. Both nanoparticles are modified with recognition
units that interact with the analyte to form a sandwich-type structure. The magnetic
properties of the designed system can then be used to separate the sandwich structures [158, 159]. Gold nanoparticles can also be functionalized with a shell of barcode consisting of hybridized oligonucleotides. After the separation of the sandwich
structure, the strands of bar codes can be identified in the microarrays by PCR or
another analytical tool. In addition, there has been a recent report of a method for
the detection of gastric cancer in which DNA probes, magnetic nanoprobes, and silicon–gold nanoparticles are hybridized to form a sandwich structure; the conjugate
is then magnetically separated and the Au–nanoparticle released [160]. The authors
suggest that complementary and mismatched DNA can be clearly distinguished by
using inductively coupled plasma mass spectrometry in the detection of DNA with
high sensitivity and specificity.
5 Conclusions
The systematic use of DNA-based magnetic nanoplatforms shows great potential in
biotechnological fields due to the important advantages of these platforms in terms
of time and resources. In this regard, relatively cheap and high-throughput DNA
extraction procedures have overcome the main drawbacks associated with traditional
methodologies. Compared with the well-known chemical recognition mechanisms,
such as host–guest chemistry, the interaction of nucleic acids is universal and easily
modified. As a consequence, several biosensors and diagnostic methods have been
38
Reprinted from the journal
1 3
PCR quantification [153], multiple PCR assays [154], and clinical diagnosis [153,
155].
Another probe is the TaqMan assay, which is used to quantify mRNA levels of
selected genes. Two fluorescent moieties with different wavelength emissions appear
in the system. Some recent reports have included the use of MNPs as platforms for
TaqMan probes. For example, Liu et al. described a portable quantitative and selective DNA detection biosensor. In only one step, target recognition occurs as a consequence of the releasing of the invertase–DNA conjugate which can be collected with
the help of a magnet. The released invertase–DNA was used to catalyze the hydrolysis of sucrose into glucose with highly efficient sequence selectivity [156].
DNA-assembled core–satellite superstructures are other platforms used in drug
delivery, imaging, and biosensing. Tian et al. reported an on-particle rolling circle
amplification process [157] that allows rapid microRNA detection. Once the targeted microRNA is detected, the long ssDNA produced acts as the scaffold of the
core–satellite superstructure and it can be hydrolyzed by duplex-specific nuclease.
Due to hydrolyzation, MNPs are released and subsequently quantified in an optomagnetic sensor. The high capacity to discriminate single-nucleotide mismatches
opens new possibilities to use these structures in clinical applications.
The development of nanotechnology and its applications in the field of biotechnology lead to an improvement in bioanalysis. The bar-code analysis, which involves
the use of IONPs and gold nanoparticles, is a diagnostic tool used for the detection of nucleic acids and proteins. Both nanoparticles are modified with recognition
units that interact with the analyte to form a sandwich-type structure. The magnetic
properties of the designed system can then be used to separate the sandwich structures [158, 159]. Gold nanoparticles can also be functionalized with a shell of barcode consisting of hybridized oligonucleotides. After the separation of the sandwich
structure, the strands of bar codes can be identified in the microarrays by PCR or
another analytical tool. In addition, there has been a recent report of a method for
the detection of gastric cancer in which DNA probes, magnetic nanoprobes, and silicon–gold nanoparticles are hybridized to form a sandwich structure; the conjugate
is then magnetically separated and the Au–nanoparticle released [160]. The authors
suggest that complementary and mismatched DNA can be clearly distinguished by
using inductively coupled plasma mass spectrometry in the detection of DNA with
high sensitivity and specificity.
5 Conclusions
The systematic use of DNA-based magnetic nanoplatforms shows great potential in
biotechnological fields due to the important advantages of these platforms in terms
of time and resources. In this regard, relatively cheap and high-throughput DNA
extraction procedures have overcome the main drawbacks associated with traditional
methodologies. Compared with the well-known chemical recognition mechanisms,
such as host–guest chemistry, the interaction of nucleic acids is universal and easily
modified. As a consequence, several biosensors and diagnostic methods have been
38
Reprinted from the journal