| Biochemical sensors are a device that combines biological materials and chemical material with a detection platform.It can be used to detect pathogens,carcinogens,biochemical poisons,etc.Biochemical sensor have many advantages such as strong specificity,high automation level,and fast analysis speed and so on.Therefore,they have been rapidly developed and applied to various industries,such as food safety,environmental monitoring,and medical diagnosis.In this paper,highly specific and sensitive biomolecules(aptamers and antibodies)and nanomaterials are used as recognition elements in biochemical sensors.Based on electrochemical and optical methods,the biochemical sensors are constructed for rapid detection of trace heavy metals in water and disease markers in body fluid First,for the trace heavy metals detection,the detection mechanism was discussed in depth and an aptamer-based Hg2+electrochemical biosensor and Cd2+colorimetric biosensor were constructed.In addition,in terms of disease marker detection,the novel nanomaterials,MnO2 nanosheet and carbon-gold nanocomposites were prepared,and based on the portable colorimetric system,biochemical sensors were constructed for sensitive colorimetric sensing of markers in blood and urine.This research was supported by the National 973 Program and the Zhejiang Science and Technology Program.The main contents and innovations of this work are as follows:1.A design of label-free gold nanoband aptamer sensor is proposed,which can detect trace Hg2+ in water environment with high sensitivityBased on micro-nano processing technology,a gold nanoband sensor is designed and manufactured.The traditional three electrodes are integrated on a chip,and the working electrode is a gold nanoband working electrode with a 100 nm bandwidth.Compared with traditional disk electrodes,nano-scale working electrodes improve the mass transfer rate and the sensitivity of Hg2+ detection,and can regenerate the sensor by cutting edges.In order to achieve high-sensitivity detection of Hg2+,the aptamers were modified to the surface of the working electrode.In the presence of Hg2+,the aptamers captured Hg2+ and induced a conformational change from single-chail to double-chain-like,thereby promoting electron transfer.Using electrochemical impedance spectroscopy(EIS),this conformational change can be detected and analyzed.By optimizing the experimental conditions,the linear range of the proposed biomolecule-based sensor is 20 ng/L to 200 ?g/L,and the detection limit is 8 ng/L.In addition,this nanoband aptasensor is highly selective and has great potential to detect trace amounts of Hg2+ in real samples.2.A colorimetric sensing method based on aptamer-gold nanoparticles combining with the sensor system based on the smartphone was proposed,highly sensitive detection of trace Cd2+in the water environment was achievedBased on the constructed portable colorimetric system,a colorimetric method based on aptamer functionalized AuNPs was proposed and the visual detection of Cd2+was realized.AuNPs with a particle size of 15nm were successfully prepared and Cd2+affinity aptamers were adsorbed on their surfaces.The mechanism of colorimetric Cd2+detection using functionalized AuNPs was explored.The portable colorimetric system can quickly capture and analyzed colorimetric changes.The results show that the sensor to detect Cd2+ have a linear range of 2-20 ?g/L and a detection limit of 1.12 ?g/L Compared with other methods,this method uses the high specificity of aptamers for Cd2+ to enhance the selectivity,and presents the characteristics of high sensitivity,simplicity,high throughput,etc.It provides an effective method for the on-site detection of Cd2+ in practical applications3.A colorimetric sensing method based on the nanozymes-3,3,5,5-tetramethylbenzidine system was proposed,and the high-throughput biomarker in urine was realized combining with the sensor system based on the smartphone.A rapid and sensitive colorimetric method based on TMB-MnO2 nanosheets was developed for oxalate detection.MnO2 nanosheets with high repeatability and good stability were successfully prepared and used as an effective biomimetic oxidase to catalyze the reaction with TMB and thus quantitative detection of oxalate was achieved.This method shows a linear range of oxalate detection from 7.8 ?M to 250 ?M and a detection limit of 0.91 ?M,which is reduced by 10 times compared with that of the electrochemical method.And the use of multi-well plates achieved a high-throughput rapid detection,oxalate sample detection can be completed within 10 minutes.In addition,the performance of this method has been validated by testing artificial urine samples,demonstrating its great potential for urolithiasis early screening on point-of-care testing.4.A method of colorimetric immunosensor with carbon-gold nanocomposites signal amplification was explored,and the high sensitive detection of biomarker of heart failure,was preliminarily realizedThe immunosandwich method was used to detect the BNP,a biomarker of the heart failure,and the CGNs were successfully prepared.Enzyme-labeled secondary antibodies were coated on the surface of CGNs,and detection probes were prepared.The effect of sensitization and amplification was successfully achieved.The results show that the molecular biosensor has a good linear relationship in the range of 3.9?g/L-250?g/L,and the calculated detection limit is 0.92?g/L.Compared with the traditional ELISA test results,the detection limit is decreased by nearly 8 times.This method has good specificity and repeatability,and high-throughput detection.According to the detection method shown in this chapter,CGNs can be applied to any kind of immunosensor to achieve the effect of high sensitivity. |
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