CN111693585B - Semiconductor nano biosensor and preparation method thereof - Google Patents
Semiconductor nano biosensor and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a preparation method of a semiconductor nano biosensor, which is Er/Tm/Yb-Bi prepared 2 MoO 6 Placing the nano particles in water for ultrasonic treatment until the nano particles are uniformly mixed to obtain a suspension, modifying the suspension on ITO conductive glass, calcining the suspension in a muffle furnace, cooling the suspension to room temperature, and carrying out continuous ionic layer adsorption reaction on Ag 2 S is deposited on a BMO-1/ITO electrode, and then nano gold ions are modified. Immediately thereafter, a solution of the food-borne pathogenic aptamer was applied dropwise and incubated overnight at 4 ℃. And continuously dripping BSA (bovine serum albumin) to block non-specificity, and finally dripping food-borne pathogenic bacteria to successfully construct a working electrode. And then, a platinum wire electrode is used as a counter electrode, a saturated calomel electrode is used as an auxiliary electrode, the platinum wire electrode and the saturated calomel electrode are respectively placed in a PBS solution to construct a three-electrode system, AA is used as an electron donor, a xenon lamp is used as a light source, and the semiconductor nano biosensor for detecting the food-borne pathogenic bacteria is successfully constructed. The sensor has the advantages of short detection time, high specificity, low cost, potential portability and the like.
Description
Technical Field
The invention belongs to the field of food safety detection, and relates to a semiconductor nano biosensor for detecting food-borne pathogenic bacteria and a preparation method thereof.
Background
Worldwide, with the increasing dependence of people on processed foods, the number of global food-borne diseases is increased year by year. According to statistics, hundreds of millions of people worldwide cause diseases due to food pollution every year. Among them, the number of patients who are caused by microbial contamination is the first, and is the most prominent health and hygiene problem in the world at present. In recent years, the proportion of food-borne diseases in China is on the rise, and about one sixth of the population suffers from the food-borne diseases. Therefore, food poisoning and food-borne diseases caused by food-borne pathogenic bacteria become the first problems facing the food safety in China.
There are dozens of food-borne pathogenic bacteria, among which staphylococcus aureus is the most common food-borne pathogenic bacteria, and food poisoning caused by staphylococcus aureus is a food-borne disease caused by exotoxin or endotoxin produced in food. In view of the problems caused by Staphylococcus aureus, the development of a rapid detection method is urgently required. As a novel detection means, the biosensor has the advantages of convenience, time saving, high precision, simple equipment, low price, easy miniaturization and the like, the collection and the processing of data are simple and convenient, no pollution is caused, and the detection of a large-flux sample on site can be realized. There are patent and literature reports that staphylococcus aureus is detected by electrochemical immunosensors, optical fiber biosensors, fluorescence sensors, DNA sensors, and the like, but there is no report that staphylococcus aureus is detected by a photoelectrochemical aptamer sensor based on a semiconductor nanomaterial.
The photoelectrochemistry biosensor is a detection technology which is established by converting an optical signal into an electric signal by utilizing the action of a photoelectric conversion material and detecting the current change caused by a substance to be detected, integrates the advantages of electrochemistry and photoelectrochemistry, adopts excitation and detection signals in different forms, has lower background signal and higher sensitivity, and is expected to be well applied to the field of rapid detection of staphylococcus aureus.
Disclosure of Invention
To solve the above technical problems, the present invention providesThe rapidity of the sensor and the specificity of the aptamer establish a semiconductor nano biosensor method for rapidly detecting food-borne pathogenic bacteria. Proposes doping of Bi based on rare earth elements 2 MoO 6 In combination with Ag 2 The S modified biosensor is used for quickly detecting pathogenic bacteria with high sensitivity and high specificity.
The complete technical scheme of the invention comprises the following steps:
a preparation method of a semiconductor nano biosensor comprises the following steps:
Adding a certain amount of Er 2 O 3 、Tm 2 O 3 、Yb 2 O 3 The nitrate solution is dissolved in 50mL of dilute nitric acid solution (1mol/L) under the heating condition of a water bath at 90 ℃ to obtain a nitrate solution, and the solution A is recorded after the nitrate solution is completely dissolved and cooled to room temperature. 2.5mmol of Bi (NO) 3 ) 3 ·5H 2 O and 1.25mmol of Na 2 MoO 4 ·2H 2 Dissolving O in the solution A and 50mL of deionized water respectively, magnetically stirring until the O is completely dissolved to obtain a solution B and a solution C, dropwise adding the solution C into the solution B to obtain a solution D, magnetically stirring for 20min, adjusting the pH value of the solution D to 5.5 by using a 2mol/L NaOH solution to obtain a milky precipitate, transferring the milky precipitate into a 80 ℃ constant-temperature water bath kettle, magnetically stirring for 2h, washing a sample, drying overnight in a forced air drying oven for 12h at 80 ℃, grinding, calcining in a 600 ℃ muffle furnace for 4h, naturally cooling to room temperature along with the furnace, and grinding the sample again to obtain Er/Tm/Yb co-doped Bi 2 MoO 6 Powder, denoted BMO-1. Pure phase Bi is prepared by the same preparation process under the condition of not adding rare earth oxide 2 MoO 6 Powder, marked as BMO-0, for facilitating Er/Tm/Yb co-doping Bi 2 MoO 6 . With pure phase Bi 2 MoO 6 The photoelectric response performance of (c) was compared.
Step 2, preparing the nano gold particles
98mL of deionized water was added to a two-necked flask, and 2mL of 50mmol/L HAuCl was added 4 Solution of Final HAuCl 4 The concentration of the solution was 1 mmol/L. A condenser and a glass stopper were attached to each neck of the two-necked flask, and the mixture was refluxed in an oil bath at 120 ℃ with stirring. When the solution starts to reflux, the glass stopper is removed and 10mL of 38.8mmol/L sodium citrate solution is rapidly added, the color of the solution changes from light yellow to wine red within 1min, the reflux is continued for 20min, finally the heating source is closed to cool the solution to room temperature during stirring, and the solution is stored in a refrigerator at 4 ℃ for standby.
Weighing a certain amount of BMO-1 sample, adding 5mL of deionized water to prepare a BMO-1 solution with a certain concentration, ultrasonically dissolving for 60min at 40 ℃, and then grinding for 30min in a mortar to enable BMO-1 powder to form uniform suspension without fine granular sensation. And (3) dripping 10 mu L of uniform suspension on an ITO electrode, naturally drying at normal temperature without wind, calcining for 2h at 550 ℃, and naturally cooling a sample along with a furnace after the calcination to obtain the BMO-1/ITO electrode. Ag by successive ionic layer adsorption reactions 2 S is deposited on a BMO-1/ITO electrode, and the specific steps are as follows: firstly, 4 mu L of 0.1mol/L TGA is dripped on the surface of a calcined BMO-1/ITO electrode and naturally dried, the surface of the electrode is washed by deionized water, and 4 mu L of AgNO with certain concentration 3 The solution was applied dropwise to the electrode surface and dried in the dark, and finally 4. mu.L of 0.2mol/L Na was added 2 Dropping S solution on the surface of the electrode to make Ag 2 S grows fully at room temperature, and the electrode is cleaned by deionized water to remove excessive Ag 2 S to this point Ag 2 And completing the preparation of the S/BMO-1/ITO electrode. 10 μ L of the prepared Au NPs solution was applied dropwise to Ag 2 Drying the S/BMO-1/ITO electrode surface to obtain Au/Ag 2 S/BMO-1/ITO electrode. Then 10 mu L of food-borne pathogenic bacteria aptamer solution with certain concentration is dripped on Au/Ag 2 S/BMO-1/ITO electrode surface, incubated at 4 ℃ overnight. The Aptamer and Au NPs are firmly fixed on the surface of the Au NPs through the strong interaction force of Au-S bonds, TE buffer solution is used for washing the surface of the electrode to remove the non-fixed Aptamer molecules, and the Aptamer/Au/Ag is obtained 2 S/BMO-1/ITO electrode. To block non-specific binding sites, 4. mu.L of 1% (w/v) BSA was applied drop-wise to Aptamer/Au/Ag 2 S/BMO-1The surface of the ITO electrode is sealed for 1h at 4 ℃, and BSA/Aptamer/Au/Ag is obtained after washing with PBS buffer solution 2 An S/BMO-1/ITO electrode, the photocurrent of the electrode is marked as a, finally, 10 mu L of food-borne pathogenic bacteria with different concentrations are respectively dripped on the Aptamer electrode and marked as FPB, the mixture is incubated for a certain time at the temperature of 4 ℃, and the FPB/BSA/Aptamer/Au/Ag are obtained after the mixture is washed by PBS buffer solution 2 And (3) placing the S/BMO-1/ITO electrode in a refrigerator at 4 ℃ for further photocurrent detection, recording the photocurrent as b, comparing the current change quantity delta I of the S/BMO-1/ITO electrode and the photocurrent as a-b, and observing the relation between the delta I and the VP concentration.
And (3) taking the electrode prepared in the step (3) as a working electrode, a platinum wire electrode as a counter electrode, a saturated calomel electrode as an auxiliary electrode, respectively placing the electrodes in a PBS solution to construct a three-electrode system, taking AA as an electron donor to construct a biosensor, and carrying out photoelectrochemical analysis by xenon light source irradiation for detection of food-borne pathogenic bacteria.
In the step 1, the doping amount of Er ions is 2mol%, the doping amount of Tm ions is 2mol%, and the doping amount of Yb ions is 4-10mol%, respectively.
In the step 3, the concentration of BMO-1 is 6-20 mg/mL; AgNO 3 The concentration is 0.1-0.2 mol/L; the aptamer concentration is 1-5 mu mol/L; the incubation time is 30-80 min.
In step 4, the AA concentration is 0.05-0.2mol/L, and the pH value of the PBS solution is 5-11.
In step 4, the detected food-borne pathogenic bacteria include, but are not limited to, salmonella, staphylococcus aureus, campylobacter jejuni, escherichia coli, vibrio parahaemolyticus, listeria, and the like.
Has the advantages that: the invention prepares Ag 2 S and Er/Tm/Yb codoped Bi 2 MoO 6 The ITO is modified by the nano material, and the semiconductor nano biosensor is constructed for detecting food-borne pathogenic bacteria, and has the advantages and characteristics as follows:
(1) rare earth element Er/Tm/Yb codoped Bi 2 MoO 6 The compound effect of multiple rare earth elements widens the spectral response and greatly improves the photocurrent response capability.
(2) By using Ag 2 S nanoparticle modification using Ag 2 S has excellent photoelectric response property, and the response capability to photocurrent is amplified.
(3) Through the specific combination of the food-borne pathogenic bacteria and the aptamer thereof, the accuracy and specificity of the experiment are greatly improved.
(4) The photoelectrochemical aptamer sensor based on the semiconductor nano material integrates the advantages of electrochemistry and photoelectrochemistry, adopts excitation and detection signals in different forms, and has lower background signal and higher sensitivity.
(5) The semiconductor nano biosensor has the advantages of high detection speed, low cost, potential portability and the like, and the detection technology is expected to be well applied to the field of rapid detection of food-borne pathogenic bacteria.
Drawings
FIG. 1 is a schematic diagram of a construction process of a working electrode of a sensor according to the present invention.
FIG. 2(a) is a diagram of BMO-0/ITO and BMO-1/ITO photoelectricity, wherein a: BMO-0/ITO, b: BMO-1/ITO.
FIG. 2(b) shows Ag 2 S composite Bi 2 MoO 6 Photocurrent graph before and after ITO calcination, wherein a: ag 2 S/BMO-0/ITO (before calcination), b: ag 2 S/BMO-0/ITO (after calcination), c: ag 2 S/BMO-1/ITO (before calcination), d: ag 2 S/BMO-1/ITO (after calcination).
FIG. 3 is a diagram of the photocurrent of a working electrode for modifying different substances, wherein a: ITO, b: BMO-1/ITO, c: ag 2 S/BMO-1/ITO，d：Au/Ag 2 S/BMO-1/ITO，e：aptamer/Au/Ag 2 S/BMO-1/ITO，f：BSA/aptamer/Au/Ag 2 S/BMO-1/ITO，g：FPB/BSA/aptamer/Au/Ag 2 S/BMO-1/ITO。
FIG. 4(a) is a graph of photocurrent response for different concentrations of FPB;
FIG. 4(b) is a linear calibration curve for detecting FPB; in the figure, a → g: 3.2X 10 2 →3.2×10 8 CFU/mL。
FIG. 5 is a graph showing the specificity of a semiconductor nanomaterial-based photoelectrochemical aptamer sensor for detection of Staphylococcus aureus.
Detailed Description
The invention is further described with reference to the following figures and detailed description. As shown in FIG. 1, the construction process of the working electrode of the semiconductor nano biosensor comprises sequentially modifying the surface of an ITO electrode with rare earth doped Bi 2 MoO 6 Nanoparticles, Ag 2 S, Au, Aptamer, BSA and FPB (Staphylococcus aureus is taken as an example in the specific embodiment) to obtain the working electrode of the semiconductor nano biosensor, which comprises the following steps:
The weighed Er is added 2 O 3 、Tm 2 O 3 、Yb 2 O 3 Dissolving in 50mL of dilute nitric acid solution (1mol/L) under the heating condition of 90 ℃ water bath to obtain a nitrate solution, and recording as an A solution, Er when the nitrate solution is completely dissolved and cooled to room temperature 3+ 、Tm 3+ 、Yb 3+ The doping concentrations of (A) are 2mol%, 2mol% and 6 mol%, respectively. 2.5mmol of Bi (NO) 3 ) 3 ·5H 2 O and 1.25mmol of Na 2 MoO 4 ·2H 2 Dissolving O in the solution A and 50mL of deionized water respectively, magnetically stirring until the O is completely dissolved to obtain a solution B and a solution C, dropwise adding the solution C to the solution B to obtain a solution D, magnetically stirring for 20min, adjusting the pH value of the solution D to 5.5 with 2mol/L NaOH solution to obtain a milky precipitate, transferring the milky precipitate into a constant-temperature water bath kettle at 80 ℃, magnetically stirring for 2 hours, washing a sample, drying the sample in a forced air drying oven overnight at 80 ℃ for 12 hours, grinding the sample, calcining the sample in a muffle furnace at 600 ℃ for 4 hours, naturally cooling the sample to room temperature along with the furnace, and grinding the sample again to obtain Er/Tm/Yb-codoped Bi 2 MoO 6 Powder, denoted BMO-1. The pure phase Bi is prepared by the same preparation process under the condition of not adding rare earth oxide 2 MoO 6 Powder, denoted BMO-0.
Step 2, preparing the nano gold particles
98mL of deionized water was added to a two-necked flask, and 2mL of 50mmol/L HAuCl was added 4 Solution of Final HAuCl 4 The concentration of the solution was 1 mmol/L. Will be provided withA condenser and a glass stopper were attached to each neck of the two-necked flask, and the mixture was refluxed in an oil bath at 120 ℃ with stirring. When the solution starts to reflux, the glass stopper is removed and 10mL of 38.8mmol/L sodium citrate solution is rapidly added, the color of the solution changes from light yellow to wine red within 1min, the reflux is continued for 20min, finally the heating source is closed to cool the solution to room temperature during stirring, and the solution is stored in a refrigerator at 4 ℃ for standby.
(1) Weighing 0.06g of BMO-1 sample, adding 5mL of deionized water to prepare a sample solution with the concentration of 12mg/mL, ultrasonically dissolving for 60min at 40 ℃, and then grinding in a mortar for 30min to form a uniform suspension of BMO-1 powder without fine granular sensation.
(2) And (3) dripping 10 mu L of uniform suspension on an ITO electrode, naturally drying at normal temperature without wind, calcining for 2h at 550 ℃, and naturally cooling a sample along with a furnace after the calcination to obtain the BMO-1/ITO electrode.
(3) Ag by successive ionic layer adsorption reactions 2 S is deposited on a BMO-1/ITO electrode, and the specific steps are as follows: firstly, 4 mu L of 0.1mol/L TGA is dripped on the surface of a calcined BMO-1/ITO electrode and naturally dried, the surface of the electrode is washed by deionized water, and 4 mu L of 0.14mol/L AgNO is added 3 The solution was applied dropwise to the electrode surface and dried in the dark, and finally 4. mu.L of 0.2mol/L Na was added 2 Dropping S solution on the surface of the electrode to make Ag 2 S grows fully at room temperature, and the electrode is cleaned by deionized water to remove excessive Ag 2 S to this point Ag 2 And completing the preparation of the S/BMO-1/ITO electrode.
(4) 10 μ L of the prepared Au NPs solution was applied dropwise to Ag 2 Drying the S/BMO-1/ITO electrode surface to obtain Au/Ag 2 S/BMO-1/ITO electrode.
(5) Followed by the application of 10. mu.L of a 2. mu. mol/L Staphylococcus aureus aptamer solution drop-wise to Au/Ag 2 S/BMO-1/ITO electrode surface, incubated at 4 ℃ overnight. The Aptamer and the Au NPs are firmly fixed on the surface of the Au NPs through the strong interaction force of Au-S bonds, TE buffer solution is used for washing the surface of the electrode to remove the unfixed Aptamer molecules, and the Aptamer/Au/Ag is obtained 2 S/BMO-1/ITO electrode.
(6) To block non-specific binding sites, 4. mu.L of 1% (w/v) BSA was applied drop-wise to Aptamer/Au/Ag 2 The surface of the S/BMO-1/ITO electrode is sealed for 1h at 4 ℃, and BSA/Aptamer/Au/Ag is obtained after washing by PBS buffer solution 2 S/BMO-1/ITO electrode.
(7) Finally, respectively dripping 10 mu L of FPB staphylococcus aureus with different concentrations on the Aptamer electrode, fully incubating for 50min at 4 ℃, and washing by PBS buffer solution to obtain FPB/BSA/Aptamer/Au/Ag 2 And the S/BMO-1/ITO electrode is placed in a refrigerator at the temperature of 4 ℃ and is reserved for the next photocurrent detection. The partial photocurrent detection data is shown in fig. 2 and 3.
Semiconductor nano biosensor sensitivity detection
The prepared biosensor is used for sensitivity detection of staphylococcus aureus and comprises the following steps:
(1) formulation 10 2 -10 8 A cfu/mL concentration gradient staphylococcus aureus bacterial liquid;
(2) dropwise adding the staphylococcus aureus liquid prepared in the step (1) to the surface of a working electrode;
(3) the prepared electrode is used as a working electrode, a platinum wire electrode is used as a counter electrode, a saturated calomel electrode is used as an auxiliary electrode, the electrodes are respectively placed in a PBS solution to construct a three-electrode system, the pH value is 7.4, 0.13M AA is added, the photoelectric chemical analysis is carried out by the irradiation of a xenon lamp light source, and an I-t image is used as an experimental basis, as shown in figure 4. When the concentration of staphylococcus aureus is 3.2X 10 2 -3.2×10 8 When the concentration of the staphylococcus aureus is within the CFU/mL range, the change response of the photocurrent has a good linear dependence relationship with the logarithm of the concentration of the staphylococcus aureus, and a linear equation is obtained according to the corresponding relationship: 8.35log C ═ I VP 9.91, correlation coefficient R 2 It was 0.996, and the limit of detection (LOD) was 20 CFU/mL.
Experiment of specificity
The prepared photoelectrochemical immunosensor is used for specificity experiments: the dropwise addition of the staphylococcus aureus in the step (7) in the step (3) is changed into the dropwise addition of the listeria (b), the salmonella typhimurium (c) and the bacillus (d), and the normal saline (a) is used as the raw materialIs blank control. As shown in FIG. 5, 3.2X 10 as compared with the blank solution 5 The photocurrent intensity of the CFU/mL staphylococcus aureus (e) solution was significantly reduced, while the photocurrent intensities of listeria, salmonella typhimurium, and bacillus were substantially not much different from the blank solution. Therefore, the constructed aptamer sensor has excellent selectivity and specificity for detecting FPB.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (6)
1. A preparation method of a semiconductor nano biosensor is characterized by comprising the following steps:
step 1, preparing Er/Tm/Yb codoped Bi 2 MoO 6 Nanoparticles;
1.1 adding a certain amount of Er 2 O 3 、Tm 2 O 3 、Yb 2 O 3 Dissolving the nitrate into 50mL of 1mol/L dilute nitric acid solution under the water bath heating condition at the temperature of 90 ℃ to obtain a nitrate solution, and cooling the nitrate solution to room temperature after the nitrate solution is completely dissolved, and marking the solution as A solution;
1.2 adding 2.5mmol of Bi (NO) 3 ) 3 . 5H 2 Dissolving O in the solution A, and magnetically stirring until the O is completely dissolved to obtain a solution B; adding 1.25mmol of Na 2 MoO 4 . 2H 2 Dissolving O in 50mL of deionized water, magnetically stirring until the O is completely dissolved to obtain a solution C, dropwise adding the solution C into the solution B to obtain a solution D, magnetically stirring for 20min, adjusting the pH value of the solution D to 5.5 by using a 2mol/L NaOH solution to obtain a milky precipitate, transferring the milky precipitate into a constant-temperature water bath kettle at 80 ℃, magnetically stirring for 2h, washing the precipitate after water bath stirring, drying overnight in a blast drying box at 80 ℃ for 12h, grinding, calcining in a muffle furnace at 600 ℃ for 4h, naturally cooling to room temperature along with the furnace, and grinding again to obtain a product Er/Tm/Yb Bi 2 MoO 6 Powder, denoted as BMO-1:
step 2, preparing the nano gold particles
98mL of deionized water was placed in a two-necked flask, and 2mL of 50mmol/L HAuCl was added 4 Solution of Final HAuCl 4 The concentration of the solution is 1 mmol/L; respectively connecting a condenser and a glass plug to two necks of a double-neck flask, and stirring and refluxing in an oil bath kettle at the temperature of 120 ℃; when the solution starts to flow back, the glass stopper is taken down, 10mL of sodium citrate solution with the concentration of 38.8mmol/L is quickly added, the color of the solution is changed from light yellow to wine red within 1min, then the solution is continuously flowed back for 20min, finally, the heating source is closed, the solution is cooled to room temperature during stirring, and the solution is stored in a refrigerator with the temperature of 4 ℃ for standby;
step 3, constructing a working electrode of the biosensor
3.1 weighing a certain amount of BMO-1 sample, adding 5mL of deionized water to prepare a BMO-1 solution with a certain concentration, ultrasonically dissolving for 60min at 40 ℃, and then grinding for 30min in a mortar to enable BMO-1 powder to form uniform suspension without fine granular sensation; dripping 10 mu L of the uniform suspension on an ITO electrode, naturally drying at normal temperature and in a windless place, calcining for 2h at 550 ℃, and naturally cooling a sample along with a furnace after calcining to obtain a BMO-1/ITO electrode;
3.2 adsorption of Ag by successive ionic layers 2 S is deposited on a BMO-1/ITO electrode by the following specific method: firstly, 4 mu L of TGA with the concentration of 0.1mol/L is dripped on the surface of a calcined BMO-1/ITO electrode and is naturally dried, the surface of the electrode is washed by deionized water, and 4 mu L of AgNO with certain concentration 3 The solution was applied dropwise to the electrode surface and dried in the dark, and finally 4. mu.L of Na was added at a concentration of 0.2mol/L 2 Dropping S solution on the surface of the electrode to make Ag 2 S grows fully at room temperature, and the electrode is cleaned by deionized water to remove excessive Ag 2 S, preparing to obtain Ag 2 S/BMO-1/ITO electrode;
3.3 drop-coating 10. mu.L of the prepared Au NPs solution onto Ag 2 Drying the S/BMO-1/ITO electrode surface to obtain Au/Ag 2 S/BMO-1/ITO electrode; then 10 mu L of food-borne pathogenic bacterium aptamer solution with certain concentration is dripped and coated on the obtained Au/Ag 2 S/BMO-1/ITO electrode surface,incubating overnight at 4 ℃; the Aptamer and AuNPs are fixed on the surface of the Au NPs through Au-S bonds, and the surface of the electrode is washed by TE buffer solution to remove the non-fixed Aptamer molecules, so that Aptamer/Au/Ag is obtained 2 S/BMO-1/ITO electrode;
3.4 to block non-specific binding sites, 4. mu.L of BSA (bovine serum albumin) at a concentration of 1% w/v was applied dropwise to the resulting Aptamer/Au/Ag 2 Blocking the surface of the S/BMO-1/ITO electrode at 4 ℃ for 1h, washing the surface by using PBS buffer solution to obtain BSA/Aptamer/Au/Ag 2 S/BMO-1/ITO electrode, and BSA/Aptamer/Au/Ag 2 Respectively dripping 10 mu L of food-borne pathogenic bacteria with different concentrations on the S/BMO-1/ITO electrode to obtain FPB/BSA/Aptamer/Au/Ag 2 S/BMO-1/ITO electrode, incubating for a certain time at 4 ℃, washing with PBS buffer solution to obtain FPB/BSA/Aptamer/Au/Ag 2 S/BMO-1/ITO electrode, put in 4 duC refrigerator and remain to carry on the photocurrent detection of the next step;
step 4, constructing the biosensor
The FPB/BSA/Aptamer/Au/Ag prepared in the step 3 2 An S/BMO-1/ITO electrode is used as a working electrode, a platinum wire electrode is used as a counter electrode, a saturated calomel electrode is used as an auxiliary electrode, the electrodes are respectively placed in a PBS solution to construct a three-electrode system, AA (ascorbic acid) is used as an electron donor, a xenon lamp is used as a light source, and a photoelectrochemical aptamer sensor based on a semiconductor nano material is constructed and used for detecting food-borne pathogenic bacteria.
2. The method for preparing a semiconductor nano biosensor as claimed in claim 1, wherein in step 1, Er/Tm/Yb is co-doped with Bi 2 MoO 6 In the nano particles, the doping amount of Er ions is 2mol%, the doping amount of Tm ions is 2mol%, and the doping amount of Yb ions is 4-10 mol%.
3. The method for preparing a semiconductor nano biosensor according to claim 1, wherein in step 3.1, the concentration of BMO-1 is 6-20 mg/mL; AgNO 3 The concentration is 0.1-0.2 mol/L; the concentration of the food-borne pathogenic bacterium aptamer solution is 1-5 mu mol/L; the incubation time is 30-80 min.
4. The method for preparing a semiconductor nano biosensor according to claim 1, wherein in step 4, the concentration of AA is 0.05-0.2mol/L, and the pH value of PBS solution is 5-11.
5. The method for preparing a semiconductor nano biosensor as claimed in claim 1, wherein the food-borne pathogenic bacteria detected in step 4 is staphylococcus aureus.
6. The semiconductor nano biosensor for detecting food-borne pathogenic bacteria prepared according to the method of any one of claims 1 to 5.
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