Preparation method of organic photoelectrochemical transistor sensing platform for detecting cortisol based on dispersed polydopamine microspheres

Abstract

The invention discloses a preparation method of an organic photoelectrochemical transistor sensing platform for detecting cortisol, and belongs to the technical field of photoelectrochemical sensors. The prepared photoelectrochemical sensor has high sensitivity, excellent selectivity and good stability, and can be widely applied to the fields of biological detection, environmental monitoring and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectrochemical sensors, specifically to a photoelectrochemical sensor based on nanomaterial modification and a preparation method thereof; the technical field mainly relates to nanomaterial modification, organic semiconductor materials, biomolecular recognition, and their application in biological detection and environmental monitoring. BACKGROUND

[0002] An electrochemical sensor is a detection device combining photoelectron technology and electrochemical technology, which can detect the presence and concentration of target substances through changes in optical signals; such sensors have wide application prospects in environmental monitoring, biomedical detection, food safety, and other fields; however, existing photoelectrochemical sensors mainly rely on traditional semiconductor materials such as indium tin oxide (ITO) and cadmium sulfide (CdS), which have good photoconductivity but still have certain limitations in sensitivity, selectivity, and stability; in addition, traditional preparation methods are usually complex and have high preparation costs, limiting their popularization and application in practical applications.

[0003] In recent years, with the rapid development of nanomaterials and functional polymers, researchers have begun to explore the application of new nanomaterials in photoelectrochemical sensors; for example, polydopamine nanospheres have become an ideal material for improving sensor sensitivity and selectivity due to their excellent photoelectric properties and biocompatibility; in addition, the introduction of functional polymers such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) not only enhances the conductivity of the material but also improves the stability and reliability of the sensor; by optimizing the preparation process, simplifying the preparation process, and reducing costs, the performance of new photoelectrochemical sensors has been significantly improved, laying a solid foundation for their widespread application in practical applications.

[0004] Based on the above research background, the present application proposes a photoelectrochemical sensor based on new nanomaterial modification and a preparation method thereof; by introducing polydopamine nanospheres and functional polymers, the sensitivity and selectivity of the sensor are significantly improved; at the same time, the optimized preparation process simplifies the preparation process and reduces costs, providing new possibilities for the widespread application of photoelectrochemical sensors in environmental monitoring and biomedical detection. SUMMARY

[0005] One of the objectives of the present application is to provide an organic photoelectrochemical transistor sensing platform based on CdS material; this platform utilizes the excellent photocurrent response and large number of active sites of CdS to significantly promote the loading of capture antibodies, laying a foundation for subsequent detection.

[0006] The second object of the present application is to improve the separation efficiency of photo-generated electron-hole pairs by optimizing the preparation process of CdS material, thereby solving the problem of short carrier lifetime caused by carrier recombination in traditional materials, and significantly improving the performance of photoelectrochemical sensors.

[0007] The third object of the present application is to introduce zinc ion doped polydopamine nanospheres, which have signal amplification effect and specific binding ability, and cooperate with CdS material to further enhance the detection sensitivity of the sensor, providing strong support for high sensitivity detection.

[0008] The fourth object of the present application is to construct an organic photoelectrochemical transistor sensing platform with good selectivity and stability for cortisol; the platform can realize high sensitivity detection of target substances and meet the actual application requirements.

[0009] The technical scheme of the present application is as follows:

[0010] 1. A preparation method of an organic photoelectrochemical transistor sensing platform for detecting cortisol based on dispersed polydopamine microspheres, characterized by comprising the following steps: (1) Preparation of second antibody connected zinc ion doped polydopamine nanosphere composite material Accurately weigh dopamine hydrochloride 20-30 mg and zinc chloride 0.02-0.05 g, dissolve them in 10-20 mL ultrapure water, and then perform ultrasonic dispersion treatment for 3-4 minutes. Transfer the obtained suspension to a constant temperature magnetic stirrer, continuously stir at 20-25℃ for 30 minutes, and after the reaction is completed, sequentially use anhydrous ethanol and deionized water for centrifugal cleaning to neutral, and finally obtain the target product by freeze-drying technology; Disperse the prepared nanomaterial in 2 mL pH 7.4 phosphate buffer solution, add 2-3 μg / mL cortisol second antibody, and oscillate at room temperature for 20 minutes; then slowly add 1-1.5% bovine serum albumin solution to block the non-specific binding sites on the surface of the material; continue to oscillate vigorously for 15 minutes, then centrifugally clean, and finally disperse the product in 1 mL pH 7.0 phosphate buffer solution, and store at 4℃ for standby; (2) Preparation of an organic photoelectrochemical transistor sensing platform 1) Cut the indium tin oxide conductive glass into the required size and perform pre-treatment to prepare an ITO electrode; 2) Drop 10-15 μL of photoelectric material CdS solution with a concentration of 2-3 mg / mL onto the surface of the ITO electrode, and then place it in a muffle furnace for calcination at 20-30℃ for 1-2 hours to enhance the binding strength of the photoelectric material and the electrode; 3) 2-3 μL of mercaptoacetic acid solution with a concentration of 0.5-0.6 mol / L was dropped on the CdS electrode and incubated for 0.5-0.6 hours; then 1-2 μL of the first antibody solution of cortisol with a concentration of 2-3 μg / mL, 1% bovine serum albumin solution and different concentrations of cortisol solution were sequentially added, and the mixture was statically placed at 4°C for 40 minutes to realize fixation and modification; 4) 2-3 μL of the prepared second antibody modified polydopamine nanosphere solution was statically placed at 37°C for 1 hour to realize specific binding of the second antibody to cortisol and fixation of the second antibody on the surface of the photoelectric material modified electrode; 5) The photoelectric modified electrode and the organic transistor were placed under a workstation for signal testing.

[0011] 2. The preparation method of the organic photoelectrochemical transistor sensing platform for detecting cortisol according to claim 1, wherein the zinc ion doped polydopamine nanospheres are prepared by the following steps: 20-30 mg of dopamine hydrochloride and 0.02-0.05 g of zinc chloride were accurately weighed and dissolved in 10-20 mL of ultrapure water, followed by ultrasonic dispersion treatment for 3-4 minutes; the obtained suspension was transferred to a constant-temperature magnetic stirrer and continuously stirred at 20-25°C for 30 minutes; after the reaction was completed, the product was washed with anhydrous ethanol and deionized water to neutralization, and finally obtained by freeze-drying technology. The prepared nanomaterials were dispersed in 2 mL of phosphate buffer solution with pH 7.4, 2-3 μg / mL of the second antibody of cortisol was added, and the mixture was oscillated at room temperature for 20 minutes; then 1-1.5% of bovine serum albumin solution was slowly dropped to block the non-specific binding sites on the surface of the material; after continuous vigorous oscillation for 15 minutes, the product was centrifugally washed, and finally dispersed in 1 mL of phosphate buffer solution with pH 7.0 and stored at 4°C for standby use.

[0012] 3. The preparation method of the organic photoelectrochemical transistor sensing platform for detecting cortisol according to claim 1, wherein the photoelectric material CdS material is prepared by the following steps: The CdS material was prepared as follows: 0.1-0.2 g of cadmium nitrate and 0.1-0.2 g of thiourea were dissolved in 10-15 mL of ethylene glycol and stirred under the condition of magnetic stirring for 20-25 minutes; the mixed solution was transferred to a reaction kettle and subjected to hydrothermal reaction at 120-140°C for 8-10 hours; after the reaction was completed, the mixture was cooled to room temperature, the precipitate was collected by centrifugation and washed with deionized water for multiple times; the washed precipitate was dried at 50-60°C for 8 hours, and the solid powder was ground to obtain the CdS nanomaterial.

[0013] 4. The method for preparing the organic photoelectrochemical transistor sensing platform for detecting cortisol according to claim 1, wherein the organic photoelectrochemical transistor is prepared by the following steps: By integrating the source electrode, the drain electrode and the organic semiconductor layer to construct a conductive channel, and taking the light-sensitive gate electrode as the control end, the specific preparation process is as follows: first, the glass substrate with a size of 10 mm x 15 mm is sequentially cleaned by ultrasonic cleaning with acetone, ethanol and ultrapure water, and then dried; after fixing the mask plate on the substrate, a 8-nanometer-thick chromium layer and a 50-nanometer-thick gold layer are prepared in sequence by using a magnetron sputtering device to form the source electrode and the drain electrode; the length and width of the conductive channel between the electrodes are respectively set to 0.2-0.3 millimeters and 6-7 millimeters; after the preparation is completed, the template is treated by plasma cleaning equipment for 1-2 minutes, and then a CdS-loaded PEDOT:PSS solution is coated on the surface of the conductive channel by spin coating to form a polymer coating; in order to enhance the bonding strength of the coating and the glass substrate, the device is placed in a nitrogen environment and annealed at 120°C for 2 hours.

[0014] Advantages of the present application (1) The organic photoelectrochemical transistor sensing platform of the present application uses CdS as a photoactive material, which provides excellent photocurrent response and a large number of active sites, promoting the loading of capture antibodies; (2) By optimizing the preparation process of the CdS material, the separation efficiency of the photo-generated electron-hole pairs is improved, and the problem of short carrier lifetime caused by carrier recombination is solved; (3) The zinc ion-doped polydopamine nanospheres introduced in the construction of the sensing platform realize signal amplification effect, and utilize their own specific binding ability to synergize with the CdS material, further enhancing the detection sensitivity; (4) The sensing platform based on the organic photoelectrochemical transistor has good selectivity and stability for cortisol, and has high sensitivity detection performance for the target substance, meeting the actual application requirements. Specific embodiments Example 1

[0015] (1) Preparation of zinc ion-doped polydopamine nanosphere composite material connected with the second antibody Accurately weigh 20 mg of dopamine hydrochloride and 0.05 g of zinc chloride, dissolve them in 20 mL of ultrapure water, and then perform 3 minutes of ultrasonic dispersion treatment, transfer the obtained suspension to a constant-temperature magnetic stirrer, continuously stir at 20°C for 30 minutes, and after the reaction is completed, sequentially perform centrifugal washing with anhydrous ethanol and deionized water to neutral, and finally obtain the target product by freeze-drying technology; The prepared nanomaterials were dispersed in 2 mL of phosphate buffer solution at pH 7.4, 2 μg / mL of cortisol secondary antibody was added, and oscillation was performed at room temperature for 20 minutes; then 1% bovine serum albumin solution was slowly added dropwise to block the non-specific binding sites on the surface of the materials; after 15 minutes of continuous vigorous oscillation, centrifugal cleaning was performed, and finally the product was dispersed in 1 mL of phosphate buffer solution at pH 7.0, and was stored at 4°C for standby use; (2) Preparation of an organic photoelectrochemical transistor sensing platform 1) Indium tin oxide conductive glass was cut into the required size and was pretreated to prepare an ITO electrode; 2) 15 μL of photoelectric material CdS solution with a concentration of 3 mg / mL was added dropwise to the surface of the ITO electrode, and then was placed in a muffle furnace for calcination at 30°C for 2 hours to enhance the binding strength of the photoelectric material and the electrode; 3) 2-3 μL of mercaptoacetic acid solution with a concentration of 0.6 mol / L was added dropwise to the CdS electrode, and was incubated for 0.6 hours; then 2 μL of cortisol primary antibody solution with a concentration of 3 μg / mL, 1% bovine serum albumin solution and different concentrations of cortisol solution were sequentially added, and were placed at 4°C for 40 minutes to realize fixation and modification; 4) 2 μL of the prepared secondary antibody modified polydopamine nanosphere solution was placed at 37°C for 1 hour to enable specific binding of the cortisol and fixation of the cortisol on the surface of the photoelectric material modified electrode; 5) The photoelectric modified electrode and the organic transistor were placed under a workstation for signal testing; 2、The zinc ion doped polydopamine nanospheres were prepared according to the following steps: 30 mg of dopamine hydrochloride and 0.05 g of zinc chloride were accurately weighed, were dissolved in 20 mL of ultrapure water, and then were subjected to ultrasonic dispersion treatment for 3 minutes; the obtained suspension was transferred to a constant-temperature magnetic stirrer, and was continuously stirred at 20°C for 30 minutes; after the reaction was completed, anhydrous ethanol and deionized water were sequentially used for centrifugal cleaning until neutralization, and finally the target product was obtained through freeze-drying technology; The prepared nanomaterials were dispersed in 2 mL of phosphate buffer solution at pH 7.4, 2 μg / mL of cortisol secondary antibody was added, and oscillation was performed at room temperature for 20 minutes; then 1.5% bovine serum albumin solution was slowly added dropwise to block the non-specific binding sites on the surface of the materials; after 15 minutes of continuous vigorous oscillation, centrifugal cleaning was performed, and finally the product was dispersed in 1 mL of phosphate buffer solution at pH 7.0, and was stored at 4°C for standby use; 3、The photoelectric material CdS material was prepared according to the following steps: Preparation of CdS material: first, 0.2 g of cadmium nitrate and 0.2 g of thiourea were dissolved in 15 mL of ethylene glycol, and stirred under magnetic stirring for 25 minutes, the mixed solution was transferred to a reaction kettle, and hydrothermal reaction was carried out at 120℃ for 8 hours, after the reaction was completed, it was cooled to room temperature, the precipitate was collected by centrifugation, and washed with deionized water for several times, the washed precipitate was dried at 50℃ for 8 hours, the solid powder was ground to obtain CdS nanomaterial; 4. The organic photoelectrochemical transistor is prepared by the following steps: By integrating the source electrode, the drain electrode and the organic semiconductor layer, a conductive channel is constructed, and the light-sensitive gate electrode is used as the control end. The specific preparation process is as follows: first, the glass substrate with a size of 10 mm × 15 mm is sequentially cleaned by ultrasonic cleaning with acetone, ethanol and ultrapure water, and then dried; after fixing the mask plate on the substrate, a 8-nanometer-thick chromium layer and a 50-nanometer-thick gold layer are prepared in sequence by using a magnetron sputtering device to form the source electrode and the drain electrode; the length and width of the conductive channel between the electrodes are respectively 0.3 millimeters and 7 millimeters; after the preparation is completed, the template is treated by plasma cleaning equipment for 2 minutes, and then a CdS-loaded PEDOT:PSS solution is coated on the surface of the conductive channel by spin coating to form a polymer coating; in order to enhance the bonding strength of the coating and the glass substrate, the device is placed in a nitrogen environment and annealed at 120℃ for 2 hours.

Claims

1. A method for preparing an organic photoelectrochemical transistor sensing platform for detecting cortisol based on dispersed polydopamine microspheres, characterized in that, Includes the following steps: (1) Preparation of zinc ion-doped polydopamine nanosphere composite material linked to a second antibody Accurately weigh 20-30 mg of dopamine hydrochloride and 0.02-0.05 g of zinc chloride, dissolve them in 10-20 mL of ultrapure water, and then perform ultrasonic dispersion for 3-4 minutes. Transfer the resulting suspension to a constant temperature magnetic stirrer and stir continuously at 20-25℃ for 30 minutes. After the reaction is complete, wash the suspension with anhydrous ethanol and deionized water in sequence until neutral. Finally, obtain the target product by freeze drying. The prepared nanomaterials were dispersed in 2 mL of pH 7.4 phosphate buffer, and 2-3 μg / mL cortisol secondary antibody was added. The mixture was shaken at room temperature for 20 minutes. Then, 1-1.5% bovine serum albumin solution was slowly added dropwise to block the non-specific binding sites on the surface of the material. After vigorous shaking for 15 minutes, centrifuge and wash the product. Finally, disperse the product in 1 mL of pH 7.0 phosphate buffer and store at 4°C for later use. (2) Fabrication of organic photoelectrochemical transistor sensing platform 1) Cut indium tin oxide conductive glass to the required size and pre-treat it to prepare ITO electrodes; 2) Add 10-15 μL of a CdS solution with a concentration of 2-3 mg / mL to the surface of the ITO electrode, and then place it in a muffle furnace and calcine it at 20-30℃ for 1-2 hours to enhance the bonding strength between the photoelectric material and the electrode. 3) Add 2-3 μL of 0.5-0.6 mol / L mercaptoacetic acid solution to the CdS electrode and incubate for 0.5-0.6 hours; then add 1-2 μL of 2-3 μg / mL cortisol primary antibody solution, 1% bovine serum albumin solution and cortisol solutions of different concentrations in sequence, and incubate at 4℃ for 40 minutes to achieve fixation and modification; 4) 2-3 μL of the prepared second antibody-modified polydopamine nanosphere solution was left to stand at 37°C for 1 hour to allow it to specifically bind with cortisol and be fixed on the electrode surface modified with optoelectronic materials. 5) Place the photoelectric modified electrode and organic transistor under the workstation for signal testing.

2. The method for preparing an organic photochemical transistor sensing platform for detecting cortisol as described in claim 1, characterized in that, The zinc ion-doped polydopamine nanospheres are prepared by the following steps: Accurately weigh 20-30 mg of dopamine hydrochloride and 0.02-0.05 g of zinc chloride, dissolve them in 10-20 mL of ultrapure water, and then perform ultrasonic dispersion for 3-4 minutes. Transfer the resulting suspension to a constant temperature magnetic stirrer and stir continuously at 20-25℃ for 30 minutes. After the reaction is complete, wash the suspension with anhydrous ethanol and deionized water in sequence until neutral. Finally, obtain the target product by freeze drying. The prepared nanomaterials were dispersed in 2 mL of pH 7.4 phosphate buffer, and 2-3 μg / mL cortisol secondary antibody was added. The mixture was shaken at room temperature for 20 minutes. Then, 1-1.5% bovine serum albumin solution was slowly added to block the non-specific binding sites on the surface of the material. After vigorous shaking for 15 minutes, the mixture was centrifuged and washed. Finally, the product was dispersed in 1 mL of pH 7.0 phosphate buffer and stored at 4°C for later use.

3. The method for preparing an organic photoelectrochemical transistor sensing platform for detecting cortisol as described in claim 1, characterized in that, The CdS optoelectronic material is prepared using the following steps: Preparation of CdS materials: First, 0.1-0.2 g of cadmium nitrate and 0.1-0.2 g of thiourea were dissolved in 10-15 mL of ethylene glycol and stirred under magnetic stirring for 20-25 minutes. The mixed solution was then transferred to a reaction vessel and subjected to a hydrothermal reaction at 120-140℃ for 8-10 hours. After the reaction was completed, the mixture was cooled to room temperature, the precipitate was collected by centrifugation, and washed several times with deionized water. The washed precipitate was dried at 50-60℃ for 8 hours and then ground into solid powder to obtain CdS nanomaterials.

4. The method for preparing an organic photoelectrochemical transistor sensing platform for detecting cortisol as described in claim 1, characterized in that, The organic photochemical transistor is fabricated using the following steps: A conductive channel is constructed by integrating the source, drain, and organic semiconductor layers, with a photosensitive gate electrode as the control terminal. The specific fabrication process is as follows: First, a 10 mm × 15 mm glass substrate is ultrasonically cleaned sequentially with acetone, ethanol, and ultrapure water, followed by drying. After fixing a mask on the substrate, an 8 nm thick chromium layer and a 50 nm thick gold layer are sequentially fabricated using magnetron sputtering to form the source and drain. The length and width of the conductive channel between the electrodes are set to 0.2-0.3 mm and 6-7 mm, respectively. After preparation, the template is treated with a plasma cleaning device for 1-2 minutes, and then a CdS-loaded PEDOT:PSS solution is spin-coated onto the surface of the conductive channel to form a polymer coating. To enhance the bonding strength between the coating and the glass substrate, the device is placed in a nitrogen environment and annealed at 120°C for 2 hours.