Disclosure of Invention
In view of the above technical problems, the present invention provides a hematocrit correction method and a biosensor testing device using the same, which can eliminate the influence of hematocrit on analyte concentration measurement and improve the accuracy of detection.
In order to achieve the purpose, the invention adopts the technical scheme that:
a hematocrit correction method includes the following steps:
s1, detecting blood sample parameters of a blood sample;
s2, measuring hematocrit: detecting hematocrit (HCT%) in the blood sample based on a correlation curve of a blood sample parameter to hematocrit;
s3, measuring initial analyte concentration value C First stage ;
S4, analyte concentration correction: using the measured hematocrit of blood (HCT%) and the measured initial analyte concentration value C Beginning of the design Calculating the final corrected analyte concentration value C of the analyte Final (a Chinese character of 'gan') 。
In a preferred embodiment, the measured response current (I) of the blood sample is used to correct the measured analyte content by converting the current hematocrit (HCT%) in the blood using a correlation curve between the hematocrit (HCT%) and the response current (I) of the blood sample.
Further, the method for determining the correlation curve of the blood sample response current (I) and the hematocrit comprises the following steps:
s2.1, obtaining standard hematocrit of different hematocrit blood samples;
s2.2, converting the blood sample with the standard hematocrit value into blood samples with different heme concentrations;
s2.3, obtaining response currents (I) of blood samples with different heme concentrations;
s2.4, establishing a correlation curve of the heme concentration and the response current (I) of the blood sample;
s2.5, converting the correlation curve of the hemoglobin concentration and the response current (I) of the blood sample into the correlation curve of the hematocrit and the response current (I) of the blood sample.
Preferably, the correlation equation of the hematocrit (HCT%) with the blood current (I) is HCT% = a X (I) + b; wherein a ranges from 0 to +0.2 and b ranges from 0 to +0.2.
More preferably, the correlation equation of the hematocrit (HCT%) with the blood current (I) is HCT% = c In (I) + d; wherein c ranges from 0 to +1,d ranges from 0 to +1.
In a preferred embodiment, the measured analyte content is corrected by using the measured red blood cell impedance phase angle (tan φ) in the blood sample and using a correlation curve between hematocrit (HCT%) and red blood cell impedance phase angle to convert to obtain the current hematocrit (HCT%) in the blood.
Further, the method for determining the correlation curve of the impedance phase angle (tan phi) of the red blood cells and the hematocrit (HCT%) comprises the following steps:
s200, testing impedance phase angles (tan phi) of red blood cells in standard different hematocrit blood samples;
s210, establishing correlation curves of different hematocrit values and impedance phase angles (tan phi) of the red blood cells.
Preferably, the correlation equation of the volume of packed red blood cells (HCT%) and the impedance phase angle of red blood cells (tan phi) is HCT% = e + tan phi 2+ f + tan phi + g; wherein e ranges from-0.01 to 0,f ranges from-0.01 to +0.01 and g ranges from 0 to 0.1.
Preferably, the analyte final corrected analyte concentration value C is calculated Final (a Chinese character of 'gan') The equation of (c) is:
C final (a Chinese character of 'gan') =C First stage (k 3+ k1 HCT%)/(1 + k2 HCT%); wherein k1 ranges from-1 to +1, k2 ranges from-1 to +1, and k3 ranges from-2 to +2.
More preferably, an analyte final corrected analyte concentration value C is calculated Final (a Chinese character of 'gan') The equation of (a) is:
C final (a Chinese character of 'gan') =k5*C First stage /(1 + k4 + HCT%) where k4 ranges from-1 to +1,k5 ranges from 0 to +2.
The invention also discloses a biosensor testing device with hematocrit correction, and the correlation curve of the hematocrit (HCT%) and the blood sample parameters in the hematocrit correction method is programmed and input into the biosensor testing device.
The invention has the following beneficial effects:
the invention relates to a hematocrit correction method and an electrochemical biosensor test device with hematocrit correction. The electrochemical biosensor determines the hematocrit of blood by the corresponding current value of the hemoglobin concentration of blood or by the phase angle tan phi of the impedance of the red blood cells of blood. And then correcting through the determined analyte concentration correction equation to calculate the final corrected concentration value of the analyte. The method is simple and easy to implement, has few interference factors and accurate test, can effectively eliminate the influence of the hematocrit on the determination of the concentration of the analyte, and improves the accuracy and the sensitivity of the result.
Detailed Description
In order to make it possible for those skilled in the relevant art to understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention are completely and clearly described in conjunction with the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The equation of the curve of hematocrit (HCT%) versus blood sample parameters is programmed into the test instrument used with the electrochemical biosensor. FIG. 1 is a schematic diagram of a two-channel electrochemical biosensor with hematocrit correction according to this embodiment, which includes a substrate layer 13, a conductive layer disposed on the substrate layer 13, and an insulating layer 11 disposed on the conductive layer. The upper end of the conducting layer comprises electrode output ends 1-5, the lower end of the conducting layer comprises a first working electrode 6, a second working electrode 7 and a counter electrode 8 shared by the first working electrode 6 and the second working electrode 7. Conductive circuits 16 are connected between the first working electrode 6, the second working electrode 7, the counter electrode 8 and the electrode output terminals 1 to 5. The first working electrode 6 and the counter electrode 8 constitute a first electrode group, and the second working electrode 7 and the counter electrode 8 constitute a second electrode group. The insulating layer 11 covers the portion above the pins of the detection electrode group, and two inverted-Y-shaped reaction channels, namely a first channel 9 (first reagent layer) and a second channel 10 (second reagent layer), are arranged according to the arrangement of the electrodes of the conductive layer. A hydrophilic layer 12 is provided in the reaction channel. The front end of the hydrophilic layer 12 is provided with a liquid inlet 14 to be detected; the hydrophilic layers 12 at the rear ends of the reaction channels are respectively provided with air holes 15. The method for measuring the hemoglobin concentration by using the electrochemical biosensor of the embodiment comprises the following test conditions: respectively applying the reaction solution to a first reaction channel and a second reaction channel under the constant potential condition of 0.2-1V for reaction; the buffer solution in the first reagent layer 9 is used to maintain the pH value in the range of 6 to 8, and the buffer solution in the second reagent layer 10 is used to maintain the pH value in the range of 5 to 8. The first reagent layer 9 includes a hemolytic agent, a first electron mediator, a first stabilizer; the second reagent layer 10 includes a surfactant, a second electron mediator, an enzyme, and a second stabilizer.
The first electron mediator comprises one of potassium ferricyanide, ferrocene, dimethylferrocene and ferrocene diformate. The second electron mediator comprises one of potassium ferricyanide, hexaammonium ruthenium trichloride, tetrathiafulvalene, ferrocene, dimethylferrocene and ferrocene diformate. The hemolytic agent in the first reagent layer comprises one or more of saponin, dodecyl sulfuric acid, hexadecyl trimethyl ammonium bromide and triton. The surfactant in the second reagent layer comprises one or more of saponin, dodecyl sulfuric acid, cetyl trimethyl ammonium bromide and triton.
FIG. 2 is a schematic flow chart of the hematocrit measurement method in the electrochemical biosensor of this embodiment.
The method comprises the following steps:
s2.1, obtaining standard hematocrit values of different hematocrit blood samples by using a capillary method or a blood cell technology instrument method;
s2.2, converting the blood sample with the standard hematocrit value into blood samples with different heme concentrations;
s2.3, obtaining response currents (I) of blood samples with different heme concentrations;
s2.4, establishing a correlation curve of the heme concentration and the response current (I) of the blood sample;
and S2.5, converting the correlation curve of the heme concentration and the response current (I) of the blood sample into the correlation curve of the hematocrit and the response current (I) of the blood sample.
The correlation equation of hematocrit (HCT%) to blood sample response current (I) may be HCT% = a × In (I) + b; wherein a ranges from about 0 to about +1,b ranges from about 0 to about +1. The equation for the plot of hematocrit (HCT%) versus heme test current value (I) is programmed into a test instrument used with an electrochemical biosensor.
S2.6, determining the hematocrit value (HCT%) of the detected blood sample according to the correlation curve of the determined current and the hematocrit.
Using the measured hematocrit value (HCT%) and the measured analyte concentration value C Beginning of the design Calculating final concentration value C of analyte Final (a Chinese character of 'gan') 。
Calculating the final concentration value C of the analyte Final (a Chinese character of 'gan') The equation of (c) may be: c Final (a Chinese character of 'gan') =k2*C Beginning of the design /(1 + k1 + HCT%), where k1 ranges from about-1 to about +1 and k2 ranges from about 0 to about +2.
The following is a specific description of the implementation of the present invention using the example of testing blood glucose in a blood sample.
Example 1: and (4) determining the hematocrit measurement equation.
The test items are mainly glucose concentration in whole blood or venous blood, and the calibration test items are mainly analytes in whole blood, such as glucose, total cholesterol, creatinine, blood ketone, urea nitrogen and the like. The first electrode group and the second electrode group adopt: gold electrodes, carbon electrodes, silver electrodes or any combination thereof.
The test conditions are that the reaction is carried out under the constant potential condition of 0.2 to 1 volt respectively applied to the first electrode group and the second electrode group. The buffer solution in the first reagent layer is used to maintain the pH in the range of 6 to 8, and the buffer solution in the second reagent layer is used to maintain the pH in the range of 5 to 8. The measuring method comprises a capillary method and a blood cell counter method.
The first reagent layer comprises hemolytic agent, electron mediator, stabilizer and the like; the second reagent layer includes a surfactant, an electron mediator, an enzyme, a stabilizer, and the like. The electron mediator in the first reagent layer comprises one of potassium ferricyanide, ferrocene, dimethylferrocene, ferrocene diformate and the like, and the electron mediator in the second reagent layer comprises one of potassium ferricyanide, ruthenium, tetrathiafulvalene, ferrocene, dimethylferrocene, ferrocene diformate and the like. The hemolytic agent in the first reagent layer comprises one or any combination of saponin, dodecyl sulfuric acid, hexadecyl trimethyl ammonium bromide, triton and the like; the surfactant in the second reagent layer comprises one or any combination of saponin, dodecyl sulfuric acid, hexadecyl trimethyl ammonium bromide, triton and the like.
A1. Preparing a plurality of blood samples with the same blood glucose concentration, wherein the blood glucose concentration is 300mg/dL, and adjusting the hematocrit to 10%, 20%, 30%, 40%, 50%, 60% and 70% respectively.
A2. The standard hematocrit blood samples were converted to blood samples of different hemoglobin concentrations as shown in fig. 3. And blood glucose sensors were used to measure the values of the blood sample response currents at different hemoglobin concentrations. As shown in table 1:
HCT%
|
hemoglobin concentration (g/L)
|
Current (uA)
|
10%
|
33.3
|
1.04
|
20%
|
66.7
|
1.48
|
30%
|
100
|
2.00
|
40%
|
133.2
|
2.92
|
50%
|
167
|
3.66
|
60%
|
199
|
5.30
|
70%
|
233
|
7.01 |
TABLE 1
A3. Using the data in table 1, linear fitting is performed with the current value as the X-axis and the hematocrit as the Y-axis to obtain the equation of the relationship between the blood (HCT%) and the current value (I), i.e.
HCT%=0.315ln(x)+0.0828 (F-1)
The measured current value (I) was substituted into the above-mentioned F-1 equation to obtain a calculated hematocrit of blood, and the correlation with the hematocrit of the actually measured standard is shown in FIG. 4.
As shown in FIG. 4, the slope of the correlation curve is 0.9564, the intercept is 0.0235, and the linear correlation coefficient R2 is 0.9978, which shows that the correlation is better.
The correlation equation (F-1) of hematocrit (HCT%) and current (I) in A3 was programmed into the instrument internal calibration chip used with the electrochemical biosensor.
Example 2: final blood sample blood glucose concentration calibration function equation determination
B1-1: preparing multiple blood samples, adjusting hematocrit to 10%, 20%, 30%, 40%, 50%, 60%, 70%, and blood glucose concentration to 110mg/dL, and calibrating with YSI 2300STAT PLUS glucose lactate analyzer, namely C YSI =110mg/dL. Testing of blood glucose concentration C with a blood glucose electrochemical sensor without hematocrit correction equation First stage . As shown in table 2.
TABLE 2
B1-2: preparing multiple blood samples, adjusting hematocrit to 10%, 20%, 30%, 40%, 50%, 60%, 70%, and blood glucose concentration to 300mg/dL, and calibrating with YSI 2300STAT PLUS glucose lactate analyzer, namely C YSI =300mg/dL. Testing of blood glucose concentration C with a blood glucose electrochemical sensor without hematocrit correction equation First stage . As shown in table 3.
HCT%
|
C First stage (mg/dL)
|
10%
|
440
|
20%
|
402
|
30%
|
347
|
40%
|
294
|
50%
|
252
|
60%
|
196
|
70%
|
172 |
TABLE 3
B1-3: preparing multiple blood samples, adjusting hematocrit to 10%, 20%, 30%, 40%, 50%, 60%, 70%, and blood glucose concentration to 500mg/dL, and calibrating with YSI 2300STAT PLUS glucose lactate analyzer, namely C YSI =500mg/dL. Testing of blood glucose concentration C with a blood glucose electrochemical sensor without hematocrit correction equation First stage . As shown in table 4.
HCT%
|
C First stage (mg/dL)
|
10%
|
699
|
20%
|
670
|
30%
|
570
|
40%
|
498
|
50%
|
423
|
60%
|
337
|
70%
|
261 |
TABLE 4
Statistical analysis was performed using the initial data in tables 2, 3, and 4 to obtain a calibration function for the final analyte concentration as:
C final (a Chinese character of 'gan') =0.61*C First stage /(1-0.97*HCT%) (F-2)
The blood glucose concentration correction equation (F-2) obtained in example 2 was programmed and input into the internal chip of the instrument used with the electrochemical biosensor.
Fig. 5, fig. 6, and fig. 7 are comparison graphs of three different blood glucose concentrations before and after hematocrit correction, as shown in fig. 5, fig. 6, and fig. 7, the measured blood glucose concentration before hematocrit correction has a larger deviation from the YSI measurement value, and the blood glucose concentration after hematocrit correction has better consistency with the YSI test result.
The electrochemical biosensor using the hematocrit measurement and correction method of the invention is not affected by hematocrit when testing the concentration of blood analytes, and the test result is more accurate and reliable.
The following examples correct the determined analyte content by using the measured red blood cell impedance phase angle (tan. Phi.) in a blood sample, and using a correlation curve of hematocrit (HCT%) and red blood cell impedance phase angle to convert to the current hematocrit (HCT%) in the blood.
Fig. 8 is a schematic structural diagram of the electrochemical biosensor for measuring blood impedance phase angle according to the present embodiment, which includes a substrate layer 312, a conductive layer on the substrate layer 312, and an insulating layer 311 disposed on the conductive layer. One end of the conducting layer comprises 5 electrode output ends 31-35, the other end of the conducting layer is sequentially provided with a first auxiliary electrode 39, a working electrode 38, a reaction electrode 37 and a second auxiliary electrode 310, a conducting circuit 36 is connected between the reaction electrode 37, the first auxiliary electrode 39, the working electrode 38, the second auxiliary electrode 310 and the electrode output ends 31-35, a hydrophilic film layer 314 is arranged on a reaction channel at the lower end of the basal layer, and the lower end of the hydrophilic film layer 314 is provided with a liquid inlet 315 to be detected; the upper end of the hydrophilic thin film layer 314 is provided with an air hole 316, and the reaction electrode 37 and the second auxiliary electrode 310 are provided with a reagent layer 313.
The buffer solution in the reagent layer 313 maintains the pH in the range of 6 to 8.
The reagent layer 313 includes a surfactant, an electron mediator, an enzyme, and a stabilizer. The electron mediator comprises one of potassium ferricyanide, ruthenium, tetrathiafulvalene and ferrocene. The surfactant comprises one or more of saponin, dodecyl sulfuric acid, cetyl trimethyl ammonium bromide and triton. The reaction electrode and the auxiliary electrode are silver electrodes.
The method for measuring the blood impedance phase angle by the electrochemical biosensor of the embodiment comprises the following measurement conditions: the reaction is carried out under the condition of constant potential between 0.2V and 1.0V between the reaction electrode 7 and the second auxiliary electrode 10; the amplitude of the AC impedance of the AC voltage signal applied to the reaction electrode 7 and the second auxiliary electrode 10 is 0.1-0.4V, and the frequency is 100-20000Hz.
The method for determining the correlation curve of the impedance phase angle (tan phi) of the red blood cells and the hematocrit (HCT%) of the red blood cells comprises the following steps:
S200,by capillary or cytometryTesting the red blood cell impedance phase angle (tan phi) in standard different hematocrit blood samples;
s210, establishing correlation curves of different hematocrit values and impedance phase angles (tan phi) of the red blood cells;
s220, determining the hematocrit value (HCT%) of the blood sample according to the correlation curve of the predetermined impedance phase angle and the hematocrit.
The correlation equation of the volume of packed red blood cells (HCT%) and the impedance phase angle of red blood cells (tan phi) is HCT% = e tan phi 2+ f tan phi + g; wherein e ranges from-0.01 to 0,f ranges from-0.01 to +0.01 and g ranges from 0 to 0.1.
Example 3: and (4) determining the hematocrit measurement equation.
The test items are mainly glucose concentration in whole blood or venous blood, and the calibration test items are mainly analytes in whole blood, such as glucose, total cholesterol, creatinine, blood ketone, uric acid and the like. The first electrode group and the second electrode group adopt: gold electrodes, carbon electrodes, silver electrodes, or any combination thereof.
The test conditions were that the reaction was carried out under a constant potential applied to the second electrode group of 0.2-1.0V. The amplitude of the AC impedance of the AC voltage signal applied to the first electrode set is 0.1-0.4V, and the frequency is 100-20000Hz. The buffer solution in the second reagent layer is used to maintain the pH in the range of 6 to 8. The measurement methods include capillary method, cytometry method and the like. The second reagent layer comprises a surfactant, an electron mediator, an enzyme, a stabilizer and the like; wherein the electron mediator comprises one of potassium ferricyanide, hexaammonium ruthenium trichloride, tetrathiafulvalene, ferrocene and the like; the surfactant comprises one or any combination of saponin, dodecyl sulfuric acid, cetyl trimethyl ammonium bromide, triton, etc.
A1. Preparing a plurality of blood samples with the same blood glucose concentration, wherein the blood glucose concentration is 110mg/dL, and adjusting the hematocrit to 10%, 20%, 30%, 40%, 50%, 60% and 70% respectively.
A2. Different hematocrit values (HCT%) of the blood samples were tested for impedance phase angle values phi with the blood glucose sensor. As shown in table 5:
HCT%
|
impedance phase angle value phi (DEG)
|
tanφ
|
10%
|
74.5
|
3.16
|
20%
|
72.6
|
3.19
|
30%
|
71.4
|
2.98
|
42%
|
68.7
|
2.56
|
50%
|
63.4
|
2.00
|
60%
|
56.7
|
1.52
|
70%
|
45.9
|
1.03 |
TABLE 5
A3. Using the data in table 5, with the erythrocyte impedance phase angle tangent tan phi as the X axis and the hematocrit of blood as the Y axis, a linear fit is performed, as shown in fig. 9, to obtain the equation of the relationship between blood (HCT%) and impedance phase angle tan phi, that is:
HCT%=-0.0334*tanφ^2-0.0724*tanφ+0.8019 (F-3)
the measured impedance phase angle tan phi was substituted into the above-described F-3 equation to obtain a calculated hematocrit, and the correlation with the measured standard hematocrit is shown in FIG. 10.
As shown in FIG. 10, the slope of the correlation curve is 0.9924, the intercept is 0.0028, and the linear correlation coefficient R2 is 0.9916, which shows that the correlation is better.
The correlation equation (F-1) of hematocrit (HCT%) and impedance phase angle tan φ in A3 was programmed into the instrument internal calibration chip used with the electrochemical biosensor.
Example 4: and finally determining the blood glucose concentration in the blood sample by using a calibration function equation.
B1-1: preparing multiple blood samples, adjusting hematocrit to 10%, 20%, 30%, 40%, 50%, 60%, 70%, and blood glucose concentration to 110mg/dL, and calibrating with YSI 2300STAT PLUS glucose lactate analyzer, namely C YSI =110mg/dL. Testing of blood glucose concentration C with a blood glucose electrochemical sensor without hematocrit correction equation First stage . As shown in table 6:
HCT%
|
C first stage (mg/dL)
|
10%
|
159
|
20%
|
143
|
30%
|
133
|
40%
|
111
|
50%
|
95
|
60%
|
75
|
70%
|
60 |
TABLE 6
Statistical analysis was performed using the initial data in table 6 to obtain a calibration function for the final analyte concentration as:
C terminal =0.59*C First stage /(1-0.99*HCT%) (F-4)
The blood glucose concentration correction equation (F-4) obtained in example 4 was programmed and input into the internal chip of the instrument used with the electrochemical biosensor.
Fig. 11 is a comparison graph of blood glucose concentration before and after hematocrit correction, and as shown in fig. 11, the measured blood glucose concentration before hematocrit correction has a large deviation from the YSI measurement value, and the blood glucose concentration after hematocrit correction has a good consistency with the YSI measurement result.
The electrochemical blood glucose test strip using the hematocrit measurement and correction method of the invention is not affected by hematocrit when testing blood glucose concentration, and the test result is more accurate and reliable.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all changes in equivalent structures or equivalent processes, which are made by using the contents of the specification and the drawings, or directly or indirectly applied to other related technical fields, are also included in the scope of the present invention.