Detection Of Fe³⁺ And DNA Based On Graphene Quantum Dot

Biosensors can be used to detect bioactive molecules and thus widely used in industrial,environmental,medical and other fields.With the improvement of people's living standards,health problems have got more and more attention.It is very important to construct highly efficient and sensitive sensors to detect the bioactive molecules such as Fe3+ and DNA.As a kind of new carbon materials,graphene quantum dots(GQDs)has received much attention in recent years.It not only inherited the advantages of good conductivity,high intensity and large specific surface area of graphene,but also combined with the properties of quantum dots as the confined effect,edge effect and size effect.Thus,making it applications in sensing,bioimaging,electrical devices,optical devices and other fields.This article mainly used the properties of photoluminescence,nice conductivity and good biocompatibility of graphene quantum dots to make biosensors of Fe3+ and DNA.The main contents can be summarized as follows:(1)With citric acid as the precursor,graphene quantum dots were prepared by the bottom-up pyrolysis method.The prepared graphene quantum dots have good crystallinity and dispersion with an average particle size of 2.6 nm.The structure and optical properties of graphene quantum dots were studied by TEM,XPS,FT-IR and PL spectra.Additionally,GQDs can be used to detect Fe3+.Fe3+ can cause fluorescence quenching of GQDs.In the range of 10-70 uM,the fluorescence intensity of GQDs has a good linear relationship with the concentration of Fe3+,and the detection limit is as low as 0.5 ?M.This detection limit is more meaningful than some of the values previously reported.Meanwhile,the sensor also has good selectivity.(2)Based on the fluorescence resonance energy transfer(FRET)between GO and GQDs,a method for HBV-DNA detection was established.pDNA modified GQDs were fluorescent donors and GO was fluorescent acceptor.The effects of GO with different concentration,quenching time and incubation time for HBV-DNA detection were studied.Under optimal conditions,the detection limit is 3.4 nM(S/N=3),and the linear detection range can reach 10-130nm.It also has good selectivity.In addition,the pDNA-GQDs/GO system based on FRET technology can also be used for quantitative detection of other target NDA.(3)Based on the interaction between GQDs and single-stranded DNA we have constructed a simple but sensitive electrochemical sensing platform to detect HBV-DNA by using GQDs modified glassy carbon electrode coupled with probe DNA.The probe DNA is complementary to the HBV-DNA.In especial,the proposed sensor exhibits high sensitivity with the detection limit of 1 nM,and the linear detection range is from the 10 nM to 500 nM.It's better than or at least comparable to the previous results of the detection of HBV-DNA or similar gene sequences.Additionally,this detection method is safe,convenient and highly selective,which may have potential applications in the future.