Abstract
Quick detection of DNA sequence is vital for many fields, especially, early-stage diagnosis. Here, we develop a graphene oxide-based fluorescence quenching sensor to quickly and accurately detect small amounts of a single strand of DNA. In this paper, fluorescent magnetic nanoparticles (FMNPs) modified with target DNA sequence (DNA-t) were bound onto the modified graphene oxide acting as the fluorescence quenching element. FMNPs are made of iron oxide (Fe3O4) core and fluorescent silica (SiO2) shell. The average particle size of FMNPs was 74 ± 6 nm and the average thickness of the silica shell, estimated from TEM results, was 30 ± 4 nm. The photoluminescence and magnetic properties of FMNPs have been investigated. Target oligonucleotide (DNA-t) was conjugated onto FMNPs through glutaraldehyde crosslinking. Meanwhile, graphene oxide (GO) nanosheets were produced by a modified Hummers method. A complementary oligonucleotide (DNA-c) was designed to interact with GO. In the presence of GO-modified with DNA-c, the fluorescence intensity of FMNPs modified with DNA-t was quenched through a FRET quenching mechanism. Our study indicates that FMNPs can not only act as a FRET donor, but also enhance the sensor accuracy by magnetically separating the sensing system from free DNA and non-hybridized GO. Results indicate that this sensing system is ideal to detect small amounts of DNA-t with limitation detection at 0.12 µM.
Highlights
Since the well-known Human Genome Project unveiled the human sequence in 2000, we have been aware that almost all diseases are related to genetic disorder [1,2,3,4]
The main methods for detecting DNA sequences include polymerase chain reaction (PCR), radioisotopes, intercalating dyes exposed with UV light, and silver staining process
Synthesis of Fluorescent Magnetic Core-Shell Nanoparticles Modified with Target Oligonucleotide
Summary
Since the well-known Human Genome Project unveiled the human sequence in 2000, we have been aware that almost all diseases are related to genetic disorder [1,2,3,4]. Fluorescence resonance energy transfer (FRET) is a distance dependent, nonradioactive process. This process normally composes the excited state fluorophore (donor) and a nearby ground state fluorophore (acceptor). For the FRET quenching mechanism, the acceptor wavelength with between the emission the donor. The quenching mechanism in a hexagonal pattern with various oxygen functional groups on the surface, e.g., carboxyl, hydroxyl has been applied to study protein–protein interaction and bioimaging [16,17]. FMNPs can be applied separately from free DNA sequences, and, can accurately determine of biomolecules can be realized through binding to FMNPs [22,23]. (DNA-c), is modified with the amine group where itofcan the functional group, When hybridization occurs, the fluorescence intensity theinteract donor, with e.g., FMNPs, will be supressed. The sensor designfor fordetecting detecting target thethe fluorescence resonance energy
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