Application Of Porous Organic Frameworks Materials And Precious Metal Nanomaterials In Biosensors

Porous organic framework?POFs?materials have attracted more and more attention for their unique,excellent properties and extensive applications.Because of its adjustable pore size,large surface area and stable chemical structure,POFs are widely used in biosensing and medical diagnosis and treatment.In biosensing applications,the holes and channels of POFs can accommodate target molecules and induce specific recognition.Noble metal nanomaterials are favored by researchers for their ultra-small size,good light resistance,good biocompatibility.Two porphyrin-type porous aromatic framework materials?PAF?Fe-PAF-40?with large surface area,good electrical conductivity and low cost were synthesized in this paper.Furthermore,copper nanoclusters?Cu NCs?and gold nanorods?Au NRs?with good stability and biocompatibility were synthesized also.These materials were used to construct photoelectrochemical sensors,electrochemical sensors,and enzyme-linked immunoassays for the detection of c-reactive protein?CRP?,ochratoxin a?OTA?,and aflatoxin b1?AFB1?.?1?A label-free C-reactive protein?CRP?photoelectric immunosensor using Au nanoparticles@porous aromatic frameworks?Au NPs@PAF?as an immobilized substrate was constructed.Under the optimal conditions,the chronoamperometry method is used to detect CRP quantitatively.The photocurrent of this sensor has a good linear relationship with the concentration of CRP in the range of 0.05-60 ng/mL.The detecting limit was 0.017 ng/mL with the linear correlation coefficient of 0.9946.The average recovery was 102%.This sensor has good selectivity,which provides a sensitive method for the detection of C-reactive protein.?2?An enzyme-linked immunosorbent assay?ELISA?using gold nanoparticles@metal porous aromatic frameworks?Au NPs@PAF-40-Fe?as a marker was developed.Quantitative detection of C-reactive protein?CRP?was achieved by UV-visible spectrophotometry under optimal conditions.Absorbance has a good linear relationship with the concentration of CRP in the range of 0.05 ng/mL-2000ng/mL.The limit of detection was 0.017 ng/mL?S/N=3?,the linear correlation coefficient was 0.9921,and the average recovery was 99.5%.The ELISA has good selectivity and provides a sensitive way for detection of CRP.?3?An electrochemical aptamer sensor was constructed using iron porphyrin porous aromatic framework materials doped with Au NPs?Au NPs@PAF-40-Fe?as immobilization matrix,the alkaline phosphatase coupled with streptavidin as the label.Under the catalysis of ALP,the hydrolysis of p-nitrophenyldisodium phosphate?pNPP?produces p-nitrophenol?pNP?,and the current response of pNP can be detected by differential pulse voltammetry,thus realizing the quantitative detection of ochratoxin A?OTA?.Under optimal conditions,the linear range of this method is0.1-100 ng/mL,the detection limit is 0.033ng/mL,the linear correlation coefficient is0.9886,and the average recovery is 98.2%.This OTA aptamer sensor has good selectivity and provides a highly sensitive method for OTA detection.?4?Food safety problems caused by mycotoxins are becoming more and more prominent worldwide.Among them,aflatoxin b1?AFB1?is the most common,toxic and carcinogenic mycotoxin.Therefore,it is crucial to develop a simple,convenient and rapid electrochemical sensor for the detection of AFB1.An aflatoxin aptamer sensor with molybdenum disulfide?AuNRs@MoS₂?doped with gold nanorods as the substrate and Au nanoparticles doped Cr metal organic frameworks?Au NPs@MIL-101?Cr?-NH₂?as the mark was proposed.The quantitative determination of AFB1 was achieved through measuring the oxidation peak current of MIL-101?Cr?-NH₂ in the label by differential pulse voltammetry under the optimal conditions.The linear range of the method is 0.05⁸5 ng/mL with the detection limit of 0.017.The linear correlation coefficient is 9830,and the recovery range is between 96.59%and107.52.This aflatoxin aptamer sensor has good selectivity.?5?Copper nanoclusters?Cu NCs?were synthesized using DNA double strands as templates and copper ions and ascorbic acid as raw materials.Since the synthesized copper nanoclusters exhibited UV absorption peaks around 315 nm,a colorimetric method for detecting OTA was developed by specific binding of aptamer chains to ochratoxin a?OTA?,destroying the stable structure of the copper nanoclusters themselves,agglomerating through salt induction.Under the optimal conditions,there was a good linear relationship between the absorbance value and the concentration of OTA within the range of 0.1 ng/mL-80ng/mL,and the detection limit was 0.033 ng/mL.This method provides a new quantitative detection method for OTA.