CN204649747U - A kind of biology sensor detecting salmonella typhimurium - Google Patents

Abstract

The utility model provides a kind of biology sensor detecting salmonella typhimurium, comprises capture probe layer and RCA product layer that gold electrode and gold electrode modify successively outward; The utility model sensitivity and specificity high, salmonella typhimurium can be detected fast.

Description

A kind of biology sensor detecting salmonella typhimurium

Technical field

The utility model relates to biosensor technology field, particularly detects the biology sensor of salmonella typhimurium based on aptamer.

Background technology

Salmonella is one of important food-borne pathogens of enterobacteriaceae, in China's food poisoning case, occupy higher rate.Salmonella typhimurium is because its drug resistance is strong, route of transmission wide, infect the features such as host is many, by extensive concern.Research shows that salmonella typhimurium has extremely strong multi-drug resistant, all shows resistivity to most microbiotic.In investigation, Salmonella Typhimurium Infection quantity accounts for 17% of salmonella infection total amount then.Meanwhile, what found within the border in China more than 290 plants in Salmonella serogroup, and salmonella typhimurium is also one of modal serotype.

At present, the method being mainly used to detect salmonella typhimurium comprises biochemical identification and serotype.But the method exists self inevitable shortcoming and restriction, need, through flow processs such as Zengjing Granule, selection screening, biochemical identification, serotypes, about one week consuming time, be unfavorable for detecting the salmonella typhimurium in food quickly and accurately.Therefore, be necessary to set up a kind of efficient new method detecting salmonella typhimurium fast.

Summary of the invention

In order to solve detect salmonella typhimurium method in specificity and sensitivity is all lower, cost is high problem, the utility model provides a species specificity and highly sensitive, that cost is low, detection speed the is fast biology sensor detecting salmonella typhimurium based on aptamer.Use biology sensor of the present invention, Salmeterol fluticasone propionate limit can reach 1 × 10 ^-16mol/ml.

The utility model additionally provides the preparation method of the biology sensor detecting salmonella typhimurium based on aptamer.

4 DNA chains have been used altogether, respectively: HAP, padlock probe, ligation probe, capture probe in the utility model.

Its sequence is respectively:

HAP：5’- TCT TGC CTA CGT CA T TTT TTT T AG TAA TGC CCG GTA GTT ATT CAA AGA TGA GTA GGA AAA GAT AGG CAA GA-3’（SEQ ID NO：1）；

padlock probe：5’-p- TGA CGT AGG CAA GAT AGA G GA GAC CCA GTA GCC AGA TGT AGC TTC GTA GGA CTT AAAGGT AGT TGG AGC TGT-3’（ SEQ ID NO：2）；

ligation probe：5’-TCT TGC CTA CGT CAA CAG CTC CAA CTA CC-3’（ SEQ ID NO：3）

capture probe：5’-GAG ACC CAG TAG CCA GAT GTA GCT-SH-3’（ SEQ ID NO：4）；

In HAP, middle underscore partial sequence is aptamers sequence.

Padlock probe: middle dashed part is identical with capture probe sequence.

In the sequence HAP of wherein hairpin structure, middle underscore partial sequence is the aptamers of object salmonella typhimurium, can combine closely with the specific identification of object.5 ' the end underscore part exposed due to distortion is the primer sequence of rolling-circle replication, can in ring in padlock probe 5 ' end underscore part be combined, initial rolling-circle replication process.

5 ' the end phosphorylation of padlock probe, and the sequence of the sequence of underscore part and 3 ' end portion is held with 5 ' of ligation probe respectively and 3 ' hold complementation, can connect into ring under the effect of T4 DNA ligase.

3 ' of capture probe terminal modifiedly has sulfydryl (-SH), stable Au-S key can be formed with gold electrode, thus capture probe is fixed on electrode surface, 5 ' end is containing the sequence identical with padlock probe ring texture internal sequence (underlining part), (Rolling Circle Amplification can be amplified with rolling ring, RCA) product combines, thus plays the effect of catching.

Two kinds of enzyme: Phi 29 archaeal dna polymerases and T4 DNA ligase has been used in the utility model.Phi 29 archaeal dna polymerase has chain extension and permutation function simultaneously, the reaction that the 5'-P end of the adjacent DNA chain of T4 DNA ligase catalysis and 3'-OH end combine with phosphodiester bond, needs ATP to make coenzyme.

In the utility model, the detection of salmonella typhimurium realizes in homogeneous phase solution, and the mode of amplifying by rolling ring realizes the amplification of signal, thus realizes the highly sensitive detection of salmonella typhimurium, and obtains lower Monitoring lower-cut.

Padlock probe completes annulation under the effect of primer and T4 DNA ligase.Primer needed for the aptamers of object and RCA is had in the DNA of hairpin structure, having object to deposit in case, this aptamers sequence can also combine with it by specific identification object, and transformation of configuration occurs, thus the DNA chain of hairpin structure is opened, expose primer sequence simultaneously.Ring texture now in homogeneous phase just can with the primer end generation complementary pairing of the hairpin structure opened, thus ring texture and HAP to be secured together.Now under the acting in conjunction of Phi 29 archaeal dna polymerase and dNTP, take ring texture as template, RCA reaction occurs under primer effect, what obtain macromolecule copies product, be RCA product, and MB can be attached on product, along with constantly carrying out of RCA reaction, the MB quantity be attached on product constantly increases, thus signal is amplified.

In homogeneous reaction, the reaction conditions of annulation and RCA is 37 DEG C, and the reaction time is 2 h.

Detect a biology sensor for salmonella typhimurium, comprise gold electrode, gold electrode is modified with capture probe layer and RCA product layer outward successively from interior;

Described biology sensor, the thickness of capture probe layer is the thickness of 10 ± 2 nm, RCA product layer is 30 ± 2 nm.

The preparation method of described biology sensor, comprises the following steps:

(1) pre-service is carried out to electrode;

(2) capture probe layer is modified electrode surface;

(3) mixed solution of hatching is added drop-wise on the electrode having modified capture probe layer, 37 DEG C, hatches 2 h.

Described preparation method, the operation steps of preferably capture probe layer being modified electrode surface is as follows: be added drop-wise to through pretreated electrode surface by capture probe 10 μ L, hatch 2 h at 25 DEG C.

Described preparation method, operation steps is as follows:

(1) by aqua sterilisa, 10 × buffer damping fluid, HAP and object to be measured add in No. 1 centrifuge tube, shake 30 s, the constant temperature oven putting into 37 DEG C hatches 2h;

(2) in No. 2 centrifuge tubes, add padlock probe, ligase, ligation probe, shake 30 s, the constant temperature oven putting into 37 DEG C hatches 2 h;

(3) in No. 1 centrifuge tube, add the 2nd step products therefrom, polymerase and dNTP, shake 30 s, the constant temperature oven putting into 37 DEG C hatches 2 h;

(4) mixed solution of hatching is added drop-wise on the electrode having modified capture probe layer, electrode is continued be placed in the constant temperature oven of 37 DEG C and hatch 2 h, cleaning;

(5) electrode is inserted in MB solution, hatches 10 min for 37 DEG C, cleaning;

Described biology sensor, HAP(mole), padlock probe(mole), ligation probe(mole), polymerase (vigor), ligase (vigor) and dNTP(vigor) mole be 1:1:1:2:40:2 with the ratio of activity.

Described preparation method, preferably carrying out pretreatment operation to electrode is that electrode carries out polishing in the oxidation aluminium paste of 0.3 and 0.05 μm, until in minute surface, rinses with PBS and intermediate water.

the detection mode of this utility model is Electrochemical Detection, utilizes traditional three-electrode system.Ag/AgCl is contrast electrode, and platinum filament is to electrode, and the gold electrode of modification is working electrode.Before testing, first by Au-S key, capture probe is fixed to electrode surface.Then reacted homogeneous phase solution is modified electrode surface, then hatch 2h at 37 DEG C and make the capture probe of the RCA product in homogeneous phase and electrode surface complete hybridization reaction, thus RCA product is fixed to electrode surface.Then the redox peak of MB is detected by three electrode work systems.Take Ag/AgCl as contrast electrode, be to electrode with Pt electrode, current potential is set to 0 to-0.5 V, pulse width 0.05 V, and sweep speed is 0.06 S, adopts differential pulse voltammetry technology to read the change of MB electric signal, detects object to be measured.

The utility model is based on the specific recognition of aptamer and object, and have chain extension and the metathesis of the archaeal dna polymerase of strand displacement function, the redox characteristic rolling ring amplification and methylene blue constructs aptamer biosensors.It is fast that this sensor has detection speed, and detectability is low, specificity advantages of higher, can make up the shortcomings and deficiencies of the existing detection method of salmonella typhimurium, realizes it quick, quantitatively detect accurately.

The beneficial effects of the utility model:

1, make use of the Idiotype identification of aptamer, utilize fit the achieving as recognition material of salmonella typhimurium to detect the high specific of object salmonella typhimurium;

2, make use of the connection function of ligase, achieve the Cheng Huan of padlock-probe;

3, utilize the polymerization of polymerase, achieve rolling-circle replication process, serve the effect that signal amplifies;

4, the reaction conditions of this sensor is gentle, and reaction velocity is fast;

5, due to use gold electrode, its electrode is easy, miniaturization, portable, can repeatedly use;

6, the main process of Cleaning Principle all realizes in homogeneous phase, the reaction velocity of raising, reduces the complexity of operation, achieves the quick of object, simply, and sensitive detection;

7, preparation method is simple, stable performance, electrode reproducible, is applicable to the detection of salmonella typhimurium in food security and the practical application of biology sensor industrialization;

8, the process costs making electrode is low, is applicable to requirement inexpensive in industrialization.

Accompanying drawing explanation

Fig. 1 is the structural representation of the xsect of biology sensor.

Wherein, 1 is gold electrode, and 2 is capture probe layer, and 3 is RCA product layer.

Embodiment

Below in conjunction with specific embodiment, the present invention is further described.

embodiment 1

As shown in Figure 1, a kind of biology sensor detecting salmonella typhimurium, comprises gold electrode 1, and gold electrode 1 is modified with capture probe layer 2 and RCA product layer 3 outward successively from interior.

The preparation method of biology sensor provided by the invention is as follows:

First a, gold electrode 1 carry out polishing in the oxidation aluminium paste of 0.3 and 0.05 μm, until in minute surface, repeatedly rinse with PBS and intermediate water;

B, by the capture probe(10 μM of 10 μ L) be added drop-wise to electrode surface, at room temperature hatch 2 h, by Au-S key, sulfydryl chain be fixed to electrode surface; So far capture probe layer 2 modification of electrode first comes to an end, after in homogeneous phase solution, modify RCA product layer 3 again, the modification step in homogeneous reaction is as follows:

A, by aqua sterilisa, 10 × damping fluid (buffer) appropriate, the target of the DNA chain (10 μMs) of 1 μ L HAP and 1 μ L variable concentrations (100 pM, 500 pM, 1 nM, 5 nM, 10 nM, 50 nM, 100 nM, 500 nM,

1 μM) join successively in the 1-9 centrifuge tube of preprepared sterilizing, shake 30 s, the constant temperature oven then mixed liquor of mixing being put into 37 DEG C hatches 2 h;

B, in ready 9 centrifuge tubes in addition, add padlock probe(1 μ L respectively, concentration is 10 μMs), ligase (1 μ L), ligation probe(1 μ L, concentration is 10 μMs), shake 30 s, the constant temperature oven putting into 37 DEG C hatches 2 h;

C, continue to add in 1-9 centrifuge tube b in a step and walk gained and hatch mixed liquor (10 μMs), polymerase (1 μ L) and dNTP(1 μ L), shake 30 s, the constant temperature oven then continuing the mixed liquor of mixing to put into 37 DEG C hatches 2 h;

D, c walked reacted solution (10 μ L) be added drop-wise to modified capture probe in advance electrode on, then electrode is continued to be placed in the constant temperature oven of 37 DEG C and hatches 2 h;

E, electrode is inserted MB solution (80 μMs), hatch 10 min for 37 DEG C;

F, use magnetic stirring apparatus cleaning electrode in PBS solution, each 10 min, clean 3 times altogether.

Described biology sensor, HAP(mole), padlock probe(mole), ligation probe(mole), polymerase (vigor), ligase (vigor) and dNTP(vigor) mole be 1:1:1:2:40:2 with the ratio of activity.

The preparation method of the solution used in said process:

1, PBS damping fluid is prepared by method: Na ₂hPO ₄(10 mM), NaH ₂pO ₄(10 mM), NaCl (140 mM), KCl (1 mM), MgCl ₂(1 mM), CaCl ₂(1 mM), the pH value of final solution is 7.4.

2, the PBS damping fluid configured and ultrapure water all need to carry out high-temperature sterilization process.Concrete grammar is, is placed in different conical flasks respectively by PBS and ultrapure water, then seals with masking foil and newspaper.In high-pressure sterilizing pot at the temperature of 120 DEG C sterilizing 20 min.

Take Ag/AgCl as contrast electrode, be to electrode with Pt electrode, current potential is set to 0 to-0.5 V, pulse width 0.05 V, and sweep speed is 0.06 s, adopts differential pulse voltammetry technology to read the change of MB electric signal, detects object.

Detect and find, in the concentration of object when 100pM is to 1 μM, logarithm and the size of current of target concentration are proportional, simultaneously, we continue to lower Concentration Testing on the concentration basis of 100pM, after testing when concentration is lower than 100pM, the relation of electric current and concentration no longer meets matched curve rule just, and namely therefore electric current minimum point can obtain the Monitoring lower-cut of the method is 1 × 10 ^-16mol/ml.

Above-described embodiment is the present invention's preferably embodiment; but embodiments of the present invention are not by the restriction of embodiment; other is any do not deviate from Spirit Essence of the present invention and principle under make change, modification, combination, substitute, simplify and all should be equivalent substitute mode, be included within protection scope of the present invention.

Claims (2)

1. detect a biology sensor for salmonella typhimurium, it is characterized in that, be modified with capture probe layer from the inside to surface successively at gold electrode, roll ring amplification product layer.

2. biology sensor according to claim 1, is characterized in that, the thickness of described capture probe layer is 10 ± 2 nm, and the thickness rolling ring amplification product layer is 30 ± 2 nm.