Photoelectrochemical Biosensor Of Hepatocellular Carcinoma Markers Based On Aromatic Ionic Liquids Functionalized Metal Organic Frameworks

Photoelectrochemical（PEC）biosensor is considered to be analytical technology with broad application prospects.Different from the traditional electrochemical methods,PEC sensor uses light as an excitation source to obtain the corresponding electrical signal.Due to the different energy forms between detection signal and excitation source,PEC sensor has higher sensitivity than chemiluminescence and electrochemical methods.At the same time,it also has the characteristics of miniaturization,low cost and easy operation.As a key component of PEC biosensor,photoelectric active material has an important influence on its detection sensitivity.In the construction of new PEC biosensors,regular metal-organic frameworks（MOFs）fully meet the requirements of photoelectric material modification and PEC performance improvement due to the possibility of multiple combinations of metal ions and organic ligands.In this paper,the research status,synthesis methods and characteristics of MOFs are described,especially the design and application of optoelectronic MOFs,and the research status of aromatic ionic liquids,photoelectric biosensors and tumor markers are summarized.MOFs can provide a series of strategies to enhance PEC biosensor performance.Based on this,two kinds of aromatic ionic liquids functionalized MOFs were used as photoelectric active materials.The photoelectric signal was enhanced by in-situ growth of gold nanoparticles on the surface of MOFs,which was used to construct PEC biosensor for hepatocellular carcinoma and realize efficient detection of tumor markers.The main research contents are as follows:（1）A novel metal-organic framework material（Zn-MOF）was synthesized by using[BDBMBCIm]Cl ionic liquid and Zn²⁺as organic ligands and central metal ions,respectively.To further enhance the photocurrent response of Zn-MOF,gold nanoparticles modified Zn-MOF composites（Au NPs@Zn-MOF）were prepared by in-situ reduction with sodium borohydride.The successful preparation of Au NPs@Zn-MOF was confirmed by Fourier transform infrared spectroscopy,X-ray diffraction,solid ultraviolet spectroscopy and scanning electron microscopy.Au NPs@Zn-MOF was modified on the surface of glassy carbon electrode as a photoelectric active material.After loading anti-AFP,glutaraldehyde crosslinking and bovine serum albumin（BSA）blocking,a photoelectric biosensor with specific response to AFP was obtained.With white light irradiation,the complex formed by the combination of AFP and anti-AFP led to the blocking of photogenerated carriers,resulting in the decrease of photocurrent.Under the optimal experimental conditions,the difference between the photocurrent changes before and after the recognition of AFP by the immunosensor and the logarithm of AFP concentration[lg c _AFP(ng m L^-1)]showed a linear relationship in the range of 0.005 ng m L^-1 to 15.0 ng m L^-1,and the detection limit was 1.88pg m L^-1（S/N=3）.The immunosensor was applied to the determination of AFP in clinical serum samples,and the results were basically consistent with those of enzyme-linked immunosorbent assay.The relative error was between-4.77%and 1.67%,and the recovery rates were 103.9%,104.6%and 96.2%,respectively.The AFP photoelectric immunosensor constructed by this method showed good selectivity,sensitivity,stability and repeatability,and had the potential for clinical diagnosis.（2）With the functionalized ionic liquid（[ADBMBCBIm]Cl）with anthracycline as the organic ligand and Er³⁺as the central metal ion,the hollow metal-organic framework（Er-MOF）nanospheres were synthesized by one-pot method.Subsequently,Au NPs@Er-MOF nanocomposites were successfully prepared by in-situ reduction of chloroauric acid on its surface.The morphology and structure of Au NPs@Er-MOF were confirmed by Fourier transform infrared spectroscopy,solid ultraviolet spectroscopy and scanning electron microscopy.The aptamer sensing interface of MCH/Apt-GP73/Au NPs@Er-MOF was obtained by modifying GP73 aptamer（Apt-GP73）with Au NPs@Er-MOF as photoactive element and blocking with MCH.With white light excitation,the specific capture of GP73antigen by the aptamer sensor would hinder the transmission rate of photogenerated electrons,and the photocurrent decreased significantly.Therefore,the quantitative analysis of GP73could be realized based on the change of photocurrent before and after capture.The experimental conditions such as ascorbic acid（AA）concentration and incubation time of GP73 were further optimized.The detection limit of GP73 reached 1.17 pg m L^-1（S/N=3）.The photocurrent response showed a good linear relationship with the logarithm of GP73concentration in the range from 0.01 ng m L^-1 to 25 ng m L^-1.To investigate the accuracy of clinical analysis of the aptamer sensor,the human serum containing different concentrations of GP73 was determined,and the results were basically consistent with those of enzyme-linked immunosorbent assay.The relative errors were in the range from-4.91 to4.67%,and the recoveries were 107%,95%and 104%,respectively,indicating that the aptamer sensor had the potential for clinical diagnosis of tumor marker GP73.