Novel Near-infrared Fluorescent Nanoprobe For Detection Of Tumor Marker Circulating Tumor DNA

Early and effective diagnosis of cancer can greatly improve the cure rate of patients.If you want to find the trace of cancer before the most advanced medical imaging technology screening,and realize the ultra-early screening of cancer,the help of cancer biomarkers was needed.Circulating tumor DNA(ctDNA),as the main detection object of emerging liquid biopsy technology,carries the genetic information consistent with the primary tumor,which can effectively predict the development of cancer.The rapid molecular diagnostic technology of ctDNA has become one of the most clinically meaningful liquid biopsies for noninvasive and timely diagnosis.However,the existing ctDNA detection technology still has some challenges.The PCR-based technology would be affected by factors such as nucleic acid contamination,tandem mismatch,etc.,resulting in the target nucleic acid not expanding or nonselective expansion,which seriously affect the detection results.The next-generation sequencing technology is difficult to be widely used because of its high price and the need for professional assistance in sequencing analysis.Nucleic acid fluorescent probes also have some inherent defects.For example,traditional fluorescent groups have background fluorescence interference and self-absorption problems,which all affect the detection sensitivity more or less.In this paper,through the study of the characteristics of ctDNA and the use of traditional fluorescent molecular probes,we have developed and constructed novel sensitive and stable anti-interference NIR fluorescence nanoprobe used for the rapid detection of ctDNA based on Toehold-mediated DNA strand replacement reaction technology.We use upconvertion nanoparticles with large anti-stokes displacement,non-photobleaching,NIR excitation emission as the fluorescent energy donor to avoid the disadvantages of traditional fluorescent molecular probes.Gold nanocages are used as a fluorescence energy quenching group,and their high extinction ability and chemical stability are used to ensure the sensitivity and stability of the probe.Toeholdmediated DNA strand replacement reaction that is stable,efficient,and not easily affected by exogenous nucleic acids is the key to NIR fluorescent nanoprobe signal transduction.The experimental results show that the constructed NIR fluorescent nanoprobe has a good linear response to the target ctDNA with a linear range of 5 pM to 1000 pM and a detection limit of 6.30 pM(S/N=3).This NIR probe also has excellent specificity and stability,a good recognition ability for single base mutation,and can be stable under continuous laser excitation and long-term storage conditions.More importantly,the designed NIR fluorescent nanoprobes are still highly responsive in complex serum biological samples.Therefore,the sensitive,stable,and antiinterference NIR fluorescent probe designed in this paper is expected to provide a new idea for early diagnosis and rapid clinical monitoring of cancer.