Optical Nanoprobes Based Detection Of Adenosine Triphosphate, Alpha-fetoprotein, MicroRNA And Telomerase

In this paper,the functional nucleic acids were used for construction of self-assembled nanobiosensors by using precious metals and upconversion nanomaterials,in which the biosensors displayed unique circular dichroism(CD),surface enhanced Raman scattering(SERS)or luminescence.We successfully established new principles and methods for the high-sensitive and high-specific detection of biomarkers in cells and serum based on the specific recognition properties and good biocompatibility of the nanobiosensors as optically active probe.The main contents in this paper were described as follows:1.A chiral Au heterodimer sensor for high-sensitive intracellular adenosine triphosphate(ATP)detection was fabricated by using aptamer as DNA backbone and different sizes of gold nanoparticles.The CD signal had obviously response to the concentration of ATP that induced dimeric structure dissociated due to the aptamer specific recognition ATP in buffer.After entering cells,the sensor had high biocompatibility and stability,which quantified ATP in cancer cells in situ by using CD intensity.The results clearly illustrated that this method had a remarkable linear range of 1.5-4.2 mmol/L,and the intracellular detection sensitivity for ATP was 0.2 mmol/L.Chirality based intracellular detection for small mo lecule biomarker was established.2.A novel SERS biosensor for ultrasensitive detection of alpha-fetoprotein(AFP)was established based on silver nanoparticle trimers assembled based on the principle of complementary base pairing of aptamer.The electromagnetic field was significantly enhanced by coating Raman tag on the surface of silver nanoparticles as a substrate.The results identified that silver nanoparticle trimers had intensive Raman enhancement effects.The SERS-encoded sensing system for AFP was obtained with a limit of detection(LOD)of 0.097 amol/L and a linear range of 0.2 to 20 amol/L.The developed biosensor is expected to be a universal platform for quantifying other biomarkers.3.A dual-signal DNA-driven hierarchical core-satellite nanostructure for simultaneous detection micro RNA content and telomerase activity in tumor cells was assembled by gold nanorod dimers and upconversion nanoparticles.Based on the principle of complementary base pairing and primer extension,the miR-21 concentration and telomerase activity were respectively quantified by using SERS and luminescent intensity in situ after internalizing the sensor into cells.There is a good linear relationship between the Raman intensities and the concentrations of miR-21 in the range 0.021 to 22.36 amol/ng RNA,and the LOD is as low as 0.011 amol/ngRNA.The results also show that the linear telomerase detection range was from 0.6×10-12 to 31×10-12 IU with a LOD of 3.2×10-13 IU.This strategy paves a way for dual-signal based simultaneous detection of intracellular cancer markers.