Department of Biomedical Engineering, University of Western Ontario, London, ON N6A 5B9, Canada.
Department of Chemical and Biochemical Engineering, University of Western Ontario, London, ON N6A 5B9, Canada.
Biosensors (Basel). 2019 May 30;9(2):74. doi: 10.3390/bios9020074.
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 (FeO) core and fluorescent silica (SiO) 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.
快速检测 DNA 序列对于许多领域至关重要，特别是在早期诊断方面。在这里，我们开发了一种基于氧化石墨烯的荧光猝灭传感器，用于快速准确地检测少量单链 DNA。在本文中，荧光磁性纳米粒子（FMNP）被修饰有目标 DNA 序列（DNA-t），并结合到作为荧光猝灭元件的改性氧化石墨烯上。FMNP 由氧化铁（FeO）内核和荧光硅（SiO）壳组成。FMNP 的平均粒径为 74±6nm，从 TEM 结果估计，SiO 壳的平均厚度为 30±4nm。研究了 FMNP 的光致发光和磁性能。通过戊二醛交联将目标寡核苷酸（DNA-t）连接到 FMNP 上。同时，通过改进的 Hummers 法制备氧化石墨烯（GO）纳米片。设计了互补寡核苷酸（DNA-c）与 GO 相互作用。在 GO 修饰有 DNA-c 的存在下，FMNP 修饰的 DNA-t 的荧光强度通过 FRET 猝灭机制被猝灭。我们的研究表明，FMNP 不仅可以作为 FRET 供体，还可以通过磁性将传感系统与游离 DNA 和非杂交的 GO 分离来提高传感器的准确性。结果表明，该传感系统非常适合检测少量的 DNA-t，检测限为 0.12µM。
