CN108776077B - Biosensor and detection method - Google Patents

Biosensor and detection method Download PDF

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CN108776077B
CN108776077B CN201810793952.1A CN201810793952A CN108776077B CN 108776077 B CN108776077 B CN 108776077B CN 201810793952 A CN201810793952 A CN 201810793952A CN 108776077 B CN108776077 B CN 108776077B
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iii
qcm
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arsenic
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CN108776077A (en
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徐斐
袁敏
叶泰
于劲松
曹慧
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University of Shanghai for Science and Technology
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    • G01N5/00—Analysing materials by weighing, e.g. weighing small particles separated from a gas or liquid
    • G—PHYSICS
    • G01—MEASURING; TESTING
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Abstract

The invention provides a biosensor for detecting arsenic (III). A mercaptoethylamine molecular membrane is formed on the surface of a Quartz Crystal Microbalance (QCM) gold electrode through self-assembly to capture arsenite ions, and a piezoelectric sensing system capable of detecting arsenite (III) with high sensitivity is constructed by utilizing the specific binding capacity between an oligonucleotide aptamer and the arsenite ions. And based on the fact that the change of the frequency signal of the QCM electrode is in direct proportion to the concentration of arsenite, the quantitative detection of arsenite (III) is realized by determining the frequency signal of the electrode. The biosensor and the detection method provided by the invention have the advantages of simple operation, low cost, high detection sensitivity and strong specificity, and can realize high-efficiency detection of arsenite.

Description

Biosensor and detection method
Technical Field
The invention relates to the field of sensors, in particular to a biosensor and a detection method.
Background
Arsenic (III) has strong toxic action on animals and plants, and has become a common environmental poison due to the increasing pollution of arsenic (III) in soil, water and crops, thereby attracting global attention. The current detection means mainly comprise an arsenic spot method, a silver salt method, an atomic absorption spectrometry and an atomic fluorescence spectrometry. The first two means are chemical methods, are relatively complicated to operate, have low sensitivity and are not suitable for the requirements of modern development; the latter two detection means are instrumental analysis methods, which have high accuracy, but the required instruments are expensive, require the operation of professionals, are labor-consuming and time-consuming, and are difficult to meet the requirements of large-scale application and real-time in-situ detection. Therefore, it is of great significance to develop a rapid, simple, low-cost and high-sensitivity arsenic (III) detection means.
The piezoelectric sensor is a biosensor which is developed rapidly in recent years, has high sensitivity and high specificity of quality response, is simple and rapid to detect, and is easy to standardize. Quartz Crystal Microbalance (QCM) is a piezoelectric sensor, has been widely used in biology, medicine, chemistry and other fields, and has the advantages of high sensitivity, small volume, simple equipment, simple operation, low detection cost, real-time on-line detection and the like. The self-assembly monolayer film technology is a simple surface modification method, is an orderly-arranged monolayer film formed by molecules spontaneously adsorbed on a solid/liquid or gas/solid interface through chemical bond interaction, and is widely used for being fixed on the surfaces of various metals and oxides.
The piezoelectric sensor based on the mercaptoethylamine self-assembly film is mainly characterized in that a self-assembly film is modified on an electrode of a QCM, and detection is realized by utilizing the specific binding of arsenite ions and oligonucleotide aptamers. Because the self-assembled molecular layer of the sulfur-gold system is easy to form a film, simple to prepare and high in stability and orderliness, an Au-S chemical bond formed by sulfydryl of mercaptoethylamine and a gold electrode is adsorbed on the surface of the gold electrode, arsenite ions are fixed, and the detection of arsenic (III) is carried out by using a frequency change response value caused by the combination of the arsenite ions and an aptamer.
Disclosure of Invention
The present invention has been made to solve the above problems, and an object of the present invention is to provide a biosensor for rapidly detecting arsenic (iii) which is easy to manufacture, low in cost, strong in interference rejection, and high in sensitivity.
The invention provides a biosensor for detecting the concentration of arsenic (III) in a solution to be detected, which is characterized by comprising the following components: the measuring electrode is used for detecting the concentration of arsenic (III) in the solution to be measured; and the determination solution is used for assisting the determination electrode to detect the concentration of arsenic (III) in the solution to be determined, wherein the preparation method of the determination electrode comprises the following steps: taking a Quartz Crystal Microbalance (QCM) wafer, and treating the surface of the QCM wafer for 2-5 min by using a first solution; step two, cleaning the QCM wafer processed in the step one, and drying the QCM wafer; soaking the dried QCM wafer in a second solution, and placing the QCM wafer in a closed container to react for the first time at normal temperature in a dark place; step four, putting the QCM wafer processed in the step three into a third solution, and placing the QCM wafer into a closed container to react for a second time at normal temperature in a dark place; step five, cleaning the QCM wafer processed in the step four, and drying the QCM wafer to obtain the QCM wafer which is a measuring electrode, wherein the preparation method of the measuring solution comprises the following steps: the first step, the tetrachloroauric acid is heated to boiling, a disodium citrate solution is rapidly added, and the solution is cooled to room temperature after being heated for the third time, so as to prepare a nano-gold solution; secondly, mixing the nanogold solution and the oligonucleotide aptamer modified by sulfydryl according to the molar ratio of 1: 50-1: 150 for reaction for the fourth time, adding a Tris-HCl (pH7.4) buffer solution, and standing for 24 hours; and a third step of centrifuging the solution obtained in the second step on a centrifuge at the speed of 14000r/min for 30min to obtain a precipitate, washing the precipitate for a plurality of times by using a HEPES (pH7.4) buffer solution, and finally dispersing the obtained precipitate in the HEPES (pH7.4) solution to obtain a solution, namely the determination solution.
In a biosensor provided by the present invention, the biosensor may further have the following features: wherein the first solution is piranha solution (concentrated H)2S04:30％H 202＝3：1，v/v)。
In a biosensor provided by the present invention, the biosensor may further have the following features: wherein, the second solution is mercaptoethylamine solution, and the third solution is 6-mercaptohexanol.
In a biosensor provided by the present invention, the biosensor may further have the following features: wherein the first time range is 8-14 h, and the second time range is 0.5-4 h.
In a biosensor provided by the present invention, the biosensor may further have the following features: wherein the third time range is 10-30 min, and the fourth time range is 12-48 h.
In a biosensor provided by the present invention, the biosensor may further have the following features: wherein the first molar ratio is in the range of 1:50 to 1: 150.
In a biosensor provided by the present invention, the biosensor may further have the following features: wherein the average grain diameter of gold particles in the nano gold solution is 12 +/-3 nm.
The invention also provides a detection method for detecting the concentration of arsenic (III) in a solution to be detected according to the biosensor, which is characterized by comprising the following steps: s1, the frequency of the measurement electrode is detected on QCM and is denoted as F0(ii) a S2, dropping the prepared arsenous (III) acid salt standard solution with known concentration on the measuring electrode, washing after reaction, and dropping the measuring solution. After reaction, the oligonucleotide aptamer labeled by nano gold is connected and fixed on the surface of the determination electrode, so that the determination is carried outThe mass of the fixed electrode is obviously increased, and after the fixed electrode is cleaned and dried, the frequency of the fixed electrode is detected by using QCM (quaternary ammonium chloride) and is marked as F1(ii) a S3 repeating S1 and S2 to obtain frequency change Δ F of measuring electrodes corresponding to a series of arsenous (iii) acid salt standard solutions with different concentrations, and calculating Δ F ═ F0-F1Plotting the arsenous (III) acid salt with different concentrations and the corresponding frequency change to draw a standard curve; and S4, testing the delta F of the solution to be tested according to S1 and S2, and obtaining the arsenite (III) acid salt concentration in the solution to be tested according to the standard curve.
The detection method provided by the present invention may further have the following features: wherein the concentration range of arsenic (III) in the solution to be measured is measured to be 0-200 nM.
Action and Effect of the invention
According to the biosensor, the biosensor has the advantages of high detection sensitivity, strong specificity, simple operation and low cost, and can realize efficient and rapid detection of arsenic (III) because of reasonable design.
Drawings
FIG. 1 is a schematic diagram of a biosensor according to the present invention;
FIG. 2 is a graph showing the relationship between the frequency change Δ F of the measurement electrode and the concentration of arsenic (III) in a biosensor according to the present invention;
FIG. 3 is a regression equation of the frequency change Δ F of the measurement electrode and the arsenic (III) concentration; and
fig. 4 is a difference between a frequency change caused by interfering ions and a blank frequency change.
Detailed Description
In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the following embodiments are specifically described with reference to the attached drawings.
FIG. 1 is a schematic diagram of a biosensor according to the present invention.
As shown in figure 1, the detection system of arsenic (III) is constructed by combining a Quartz Crystal Microbalance (QCM) gold electrode, a mercaptoethylamine self-assembled molecular membrane and a nano-gold labeled arsenic (III) oligonucleotide aptamer: when the sample to be detected does not contain arsenic (III), the oligonucleotide aptamer marked by the nanogold cannot be connected with the mercaptoethylamine molecular membrane, the quality change of the surface of the electrode is not obvious, and the frequency change is not obvious; when the sample to be detected contains arsenic (III), the mercaptoethylamine self-assembly molecular layer on the surface of the gold electrode fully captures arsenic (III) acid radical ions, and then the oligonucleotide aptamer marked with the nano-gold is connected and fixed on the surface of the QCM gold electrode through the high-specificity affinity between the oligonucleotide aptamer and the arsenic (III) acid radical ions, so that the surface quality of the electrode is remarkably increased, and the response frequency of the QCM gold electrode crystal oscillator plate is remarkably changed. Quantitative detection of arsenous (iii) acid salt can therefore be achieved by determining the change in the frequency signal of the electrode, which is proportional to the arsenous (iii) acid salt concentration.
The invention provides a biosensor for efficiently and rapidly detecting arsenic (III) in a solution to be detected, which comprises: the measuring electrode is used for detecting arsenic (III) in the solution to be measured; and the measuring solution is used for assisting the measuring electrode to detect the arsenic (III) in the solution to be measured.
Wherein, the preparation process of the measuring electrode is as follows:
taking a Quartz Crystal Microbalance (QCM) wafer with gold plated on both sides, and using piranha solution (concentrated H)2 S0 430％H 202II, a second step of: 1, v/v) treating the surface of the QCM wafer for 5 min;
step two, washing the QCM wafer processed in the step one by ultrapure water until the residual liquid of the piranha remaining on the surface of the QCM wafer is completely removed, and then using N2Drying the QCM wafer;
soaking the QCM wafer in mercaptoethylamine solution, placing the QCM wafer in a closed container, and reacting for 12 hours at normal temperature in a dark place, wherein the QCM wafer is self-assembled;
step four, putting the QCM wafer treated in the step three into a 6-mercaptohexanol solution, and putting the QCM wafer into a closed container to react for 2 hours at normal temperature in a dark place so as to seal the nonspecific binding sites on the surface of the QCM wafer;
step (ii) ofFifthly, the QCM wafer processed in the fourth step is cleaned by ultrapure water, and then N is used2And drying the QCM wafer to obtain the QCM wafer, namely the measuring electrode, and storing the QCM wafer at 4 ℃ for later use.
The assay solution was prepared as follows:
the first step, 50mL of tetrachloroauric acid (1mM) is heated to boiling, 5mL of disodium citrate solution (38.8mM) is rapidly added, heated for 15min and then cooled to room temperature to prepare nano-gold solution, the maximum absorption wavelength of the nano-gold solution is 520nm, and the extinction coefficient xi is 2.43 x 108The concentration was 11nM, and the particle size was 12 + -3 nM.
And secondly, mixing the nanogold solution and the oligonucleotide aptamer (with the sequence of 5 '-SH-GGT AAT ACG ACT CAC TAT AGG GAG ATA CCA GCT TAT TCA ATT TTA CAG AAC AAC CAA CGT CGC TCC GGG TAC TTC TTC ATC GAG ATA GTA AGT GCA ATC T-3') modified by sulfydryl according to the molar ratio of 1:130 for reaction for 24 hours, and then adding pH7.4 Tris-HCl (0.1M NaCl,10mM Tris-HCl) for standing for 24 hours to ensure that the oligonucleotide aptamer is linearly arranged on the surface of the nanogold.
And a third step of centrifuging the solution obtained in the second step in a centrifuge at 14000r/min for 30min to obtain a precipitate, washing the precipitate 5 times with a HEPES buffer solution (25mM HEPES, 0.1M NaCl) having a pH of 7.4, and dispersing the precipitate in a HEPES buffer solution (25mM, 0.1M NaCl) having a pH of 7.4 and storing the precipitate at 4 ℃ for later use.
The detection method for detecting arsenic (III) in the solution to be detected by using the biosensor provided by the invention comprises the following steps:
s1, detecting the frequency of the sample at QCM using the self-assembled measuring electrode, denoted as F0；
S2, detecting the frequency F on the QCM0Then 20 mu L of arsenous acid (III) salt solution with certain concentration is dripped on the measuring electrode for reaction for 30min, so that arsenous acid radical ions (III) are fully captured and fixed on the surface of the electrode, the electrode is washed by double distilled water and dried by nitrogen, then 20 mu L of measuring solution is dripped, after reaction for 30min, the oligonucleotide aptamer marked by nano gold in the measuring solution is combined with the arsenous acid radical ions (III) fixed on the measuring electrode, and nano gold and oligonucleotide are adaptedThe body firmly adsorbs on the surface of the measuring electrode, the double distilled water is flushed and dried by nitrogen, the frequency of the measuring electrode is detected by using QCM (quaternary ammonium chloride), and the frequency is recorded as F1；
S3 repeating the above steps S1 and S2 to obtain a series of frequency changes Δ F of the measuring electrodes corresponding to arsenous (iii) acid salt solutions with different concentrations, and calculating Δ F ═ F0-F1And plotting the arsenite (III) ions with different concentrations and the corresponding frequency changes to draw a standard curve, as shown in FIG. 2.
FIG. 3 is a regression equation of the concentration of arsenite (III) ion and the frequency change Δ F of the measurement electrode, taken at three points in FIG. 2: Δ F0.2398CAs+9.2754, wherein: Δ F is the frequency variation in Hz, CAsIs the arsenous (III) acid radical ion concentration in nM.
S4, testing the delta F of the solution to be tested according to S1 and S2; and comparing with a standard regression equation to obtain the concentration of arsenic (III) ions in the solution to be detected.
The concentration range of arsenic (III) measured by the detection method is 0-200nM, and the lowest detection limit is 4.5 nM.
Fig. 4 is a difference between a frequency change caused by interfering ions and a blank frequency change.
As shown in FIG. 4, in order to determine the specificity of the biosensor provided by the present invention for arsenic (III) ion detection, ion solutions of mercury (II), lead (II), cadmium (II), copper (II) and arsenic (V) were prepared at concentrations of 10. mu.M, respectively, and the frequency change thereof was determined by the determination method of the present invention and compared with an arsenic (III) ion solution at a concentration of 1. mu.M. The results show that the frequency change of the mercury (II), lead (II), cadmium (II), copper (II) and arsenic (V) ion solution with the concentration of 10 mu M to the measuring system is obviously smaller than that of the arsenic (III) ion solution with the concentration of 1 mu M to the measuring system, and the frequency change of the mixed solution containing 1 mu M of arsenic (III) ions and 10 mu M of the above five ions to the measuring system is basically consistent with that of the arsenic (III) ion solution with the concentration of 1 mu M to the measuring system, thereby showing that the biosensor has specificity to the arsenic (III) ions.
Effects and effects of the embodiments
According to the biosensor, the biosensor has the advantages of high detection sensitivity, strong specificity, simple operation and low cost, and can realize efficient and rapid detection of arsenic (III) because of reasonable design.
The above embodiments are preferred examples of the present invention, and are not intended to limit the scope of the present invention.

Claims (7)

1. A biosensor for detecting the concentration of arsenic (iii) in a solution to be detected, comprising:
the measuring electrode is used for detecting the concentration of arsenic (III) in the solution to be measured; and
a determination solution for assisting the determination electrode in detecting the concentration of arsenic (III) in the solution to be determined,
the preparation method of the measuring electrode comprises the following steps:
taking a Quartz Crystal Microbalance (QCM) wafer, and treating the surface of the QCM wafer for 2-5 min by using a first solution;
step two, cleaning the QCM wafer processed in the step one, and drying the QCM wafer;
soaking the dried QCM wafer in a second solution, and placing the QCM wafer in a closed container to react for the first time at normal temperature in a dark place;
step four, putting the QCM wafer processed in the step three into a third solution, and placing the QCM wafer into a closed container to react for a second time at normal temperature in a dark place;
step five, cleaning the QCM wafer processed in the step four, drying the QCM wafer to obtain the QCM wafer which is the measuring electrode,
the preparation method of the assay solution is as follows:
the first step, the tetrachloroauric acid is heated to boiling, a disodium citrate solution is rapidly added, and the solution is cooled to room temperature after being heated for the third time, so as to prepare a nano-gold solution;
secondly, mixing the nanogold solution and the oligonucleotide aptamer modified by sulfydryl according to a molar ratio of 1: 50-1: 150 for reaction for the fourth time, adding Tris-HCl and pH7.4 buffer solution, and standing for 24 hours;
a third step of centrifuging the solution obtained in the second step in a centrifuge at 14000r/min for 30min to obtain a precipitate, washing the precipitate for several times by using a buffer solution of HEPES and pH7.4, finally dispersing the obtained precipitate in a solution of HEPES and pH7.4 to obtain a solution, namely the determination solution,
wherein the second solution is mercaptoethylamine solution, the third solution is 6-mercaptohexanol,
the oligonucleotide aptamer sequence is as follows: 5 '-SH-GGTAATACGACT CAC TAT AGG GAG ATA CCA GCT TAT TCA ATT TTA CAG AAC AAC CAA CGT CGC TCC GGG TAC TTC TTC ATC GAG ATA GTA AGT GCAATC T-3'.
2. The method for producing a biosensor in accordance with claim 1, wherein:
wherein the first solution is piranha solution, concentrated H2S04:30％H202＝3：1，v/v。
3. The method for producing a biosensor in accordance with claim 1, wherein:
the first time range is 8-14 hours, and the second time range is 0.5-4 hours.
4. The method for producing a biosensor in accordance with claim 1, wherein:
the third time range is 10-30 min, and the fourth time range is 12-48 h.
5. The method for producing a biosensor in accordance with claim 1, wherein:
wherein the average grain diameter of gold particles in the nano gold solution is 12 +/-3 nm.
6. A method for detecting a solution to be detected by the biosensor according to any one of claims 1 to 5, comprising:
s1, detecting the frequency of the measuring electrode on QCM, and marking as F0；
S2, dripping a pre-prepared arsenite (III) acid salt standard solution with known concentration on the measuring electrode, washing after reaction, dripping the measuring solution again, connecting and fixing the oligonucleotide aptamer labeled by the nanogold on the surface of the measuring electrode after reaction, obviously increasing the mass of the measuring electrode, washing and drying, detecting the frequency by using QCM (quaternary ammonium chloride), and recording the frequency as F1；
S3 repeating the above steps S1 and S2, obtaining a frequency change Δ F of the measuring electrode corresponding to a series of arsenous (iii) acid salt standard solutions with different concentrations, and calculating Δ F ═ F0-F1Plotting the arsenous (III) acid salt with different concentrations and the corresponding frequency change to draw a standard curve;
and S4, testing the delta F of the solution to be tested according to the S1 and the S2, and obtaining the concentration of arsenite (III) in the solution to be tested according to the standard curve.
7. The method for detecting a solution to be detected by the biosensor according to claim 6, wherein:
wherein the concentration range of arsenic (III) in the solution to be detected is determined to be 0-200 nM.
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