Preparation,Dual-signal Integration And Application Of Ultrasensitive Infrared Absorption Nanobioprobes

In recent years,a series of public health problems threaten the health of people seriously.The detection of biomarkers can provide an important reference for timely discovery and response to these problems.As a powerful analytical tool,the optical nanobioprobe has been widely favored by people.With the increasing demands for clinical detection in,such as,accuracy,sensitivity and linear range,it is of great practical significance to develop accurate,sensitive and wide-linear nanobioprobes.The infrared absorption?IRA?in the fingerprint area of inorganic materials shows good stability and strong resistance to environmental interference.It has unique advantages in the design of the IRA nanobioprobe to detect biomarkers.However,the related researches are still very limited.The reasonable design and performance improvement of probe material is the key to promoting its clinical application.Therefore,based on the infrared fingerprint absorption of silica,a Fe₃O₄ superparticle@SiO₂ IRA nanoprobe was first constructed in this thesis.The limitation of interface resistance on the detection sensitivity and speed was broken with the assistance of an external magnetic field.A fluorescence-IRA dual-readout probe was then designed by compounding with perylene.The detection accuracy and sensitivity were improved by mutual verification and complementation between the two signals.In addition,the carbon dots and SiO₂ were combined to further improve the detection sensitivity and broaden the detection range.Finally,upconversion nanoparticles were used to replace the carbon dots to further reduce the interference of background fluorescence on the accuracy of the assay results.This thesis provided a novel idea for the signal integration and design of optical nanobioprobes.The main research contents are as follows:?1?Aiming at the key problem that low sensitivity restricted the clinical application of the IRA probes,a Fe₃O₄ superparticle@SiO₂ nanoprobe was prepared.The infrared fingerprint absorption of the transverse-longitudinal optical phonon modes of the antisymmetric stretching vibration of Si-O-Si bonds in the SiO₂ structure was used as the output signal to detect the analyte.The adoption of Fe₃O₄ superparticle instead of Fe₃O₄ nanoparticles as the magnetic core warrants a controllable structure and a strong magnetic response.With the assistance of an external magnetic field,the probe overcame the restriction of interface resistance to improve the detection sensitivity by two orders of magnitude to 95 fM?152 pg / mL?and shorten the assay time from 2 h to 1 min.The assay performance of the IRA nanoprobe was far superior to that of the commercial ELISA kit and the ultrasensitive analysis of real serum samples was realized.?2?In order to further improve the detection sensitivity and accuracy of the optical nanoprobe,the silane derivatives of perylene imide?PDI?/SiO₂ nanoprobe was prepared.The integration of fluorescence and IRA dual signals was realized for the first time.PDI was covalently coupled to the network structure of SiO₂,which improved the fluorescence stability by 22.1% by avoiding the fluorescence quenching caused by the agglomeration and leakage of the dyes.The mutual verification and complementarity of fluorescence and IRA improved the detection sensitivity and accuracy.The sensitivity was 274.6 fg/mL and the detection range was widened to 100 ng/mL – 500 fg/mL.?3?In order to further improve the detection sensitivity and broaden the detection range of the dual-readout probe,the carbon dots@SiO₂ nanoprobe was prepared.The SiO₂ shell provided IRA as the readout signal and enhanced the fluorescence emission performance of carbon dots by the surface passivation.Therefore,the detection sensitivity was improved to 794.6 ag/mL(about 10^-12g/mL).The complementation of fluorescence and IRA signals broadened the detection range to 200 ng/mL – 1 fg/mL,which covered 9 orders of magnitude.?4?In order to further eliminate the adverse effect of background fluorescence on the dual-readout probe,NaYF₄: Yb³⁺,Er³⁺excited by near-infrared light were combined with SiO₂ to construct the upconversion luminescence?UCL?-IRA nanoprobe.The coating of SiO₂ shielded the influence of high frequency vibration groups in the detection solution on the UCL.The UCL performance of the nanoprobe was thus improved.The upconversion nanoparticles were used as solid surfactant in the microemulsion reaction system.The adjusting of the amounts of the nanoparticles controlled the aspect ratio and optical properties of the probes.The fluorescence emission performance of the probe was enhanced by nearly 5 times by this way.The sensitivity of the UCL-IRA IRAnanoprobe was 52.5 fg/mL and the detection range was 200 ng/ml – 200 fg/mL.The interference of background fluorescence was eliminated by using near-infrared light instead of UV-Vis light as the excitation light.It further improved the accuracy of the detection.