Summary of the invention
The purpose of this invention is to provide a kind of easy and simple to handle and antioxidant for clearing H that detection sensitivity is high based on gold nanoshell
2O
2The assay method of ability.
The present invention adopts following technical scheme:
Mensuration antioxidant for clearing H of the present invention
2O
2The method of ability is promptly utilized at H
2O
2Add behind the antioxidant variation of spectral quality in the mediation gold nanoshell formation system and measure antioxidant for clearing H
2O
2Ability.
Mensuration antioxidant for clearing H of the present invention
2O
2The method of ability, that is:
1. amination SiO
2Colloid micro ball, ADSORPTION OF GOLD nano particle (GNPs) forms SiO again
2/ GNPs composite particles.
2. choice reaction system final concentration is the H of 200 μ M
2O
2Antioxidant hybrid reaction with variable concentrations adds SiO again
2/ GNPs composite particles and gold chloride, SiO
2/ GNPs composite particles concentration is 6.7 * 10
-11M, gold chloride concentration is 3.3 * 10
-4M mixes and stirs.
3. utilize and add SiO in the mixed liquor of antioxidant front and back
2Antioxidant for clearing H is calculated in the variation of/GNPs composite particles spectral quality
2O
2Ability.
The present invention is concrete to adopt following technical scheme to solve the technical matters that is proposed:
A kind of antioxidant for clearing H based on gold nanoshell
2O
2The assay method of ability, step is:
1. with gold nano grain and amidized SiO
2Colloidal solution mixes, stirs, and the amount of added gold nano grain should make gold nano grain at amidized SiO
2The coverage rate calculated value on bead surface is no less than 30%, and gold nano grain is adsorbed in amidized SiO by electrostatic adsorption
2Colloidal grain surface gets SiO
2/ GNPs composite particles aqueous solution is to SiO
2After/GNPs composite particles aqueous solution is carried out centrifugal treating, remove the gold nano grain that the upper strata is not adsorbed, again the SiO after removing the gold nano grain that is not adsorbed
2Add the pure water dilution in the/GNPs composite particles aqueous solution, and make precipitation be scattered in the SiO that obtains purifying in the pure water
2/ GNPs composite particles, SiO
2The SiO of/GNPs composite particles after dilution
2Concentration in the/GNPs composite particles aqueous solution is 2 * 10
10Individual/mL~2 * 10
12Individual/mL;
2. in the phosphate buffered solution of 0.01M, add sal tartari and be 1% chlorauric acid solution as the stabilizing agent of reaction system and mass volume ratio concentration, volume mL, the quality mg of phosphate buffered solution, sal tartari and chlorauric acid solution, volume mL ratio are 20~500: 5~125: 0.3~7.5, stir, in 4 ℃ of ageings 24h at least, obtain the chlorauric acid solution that sal tartari is made stabilizing agent;
3. in the phosphate buffered solution of 0.01M, add antioxidant and H to be detected
2O
2, (antioxidant to be detected volumetric molar concentration in reaction system is 3 μ M~1200 μ M, H
2O
2Volumetric molar concentration in reaction system is 50 μ M~500 μ M), phosphate buffered solution, antioxidant and H to be detected
2O
2Volume ratio be 0.6~15: 0.02~0.5: 0.04~1, after mixing and reacting 1~5min, again to wherein adding SiO
2The sal tartari of/GNPs composite particles aqueous solution and step 2 gained is done the chlorauric acid solution of stabilizing agent, at this moment SiO
2The whole volumetric molar concentration of/GNPs composite particles in reaction system is 1.34 * 10
-11M~13.4 * 10
-11M, the whole volumetric molar concentration of gold chloride is 0.66 * 10
-4M~6.6 * 10
-4M, reaction 2~20min, remaining H
2O
2Gold chloride is reduced into gold nano grain and is deposited on SiO
2/ GNPs composite particles surface forms and coats incomplete gold nanoshell; The incomplete gold nanoshell of coating that above-mentioned reaction is formed characterizes under ultraviolet spectrophotometer, and record coats the maximum absorption wavelength of incomplete gold nanoshell aqueous solution, is designated as W
1In the time of will not adding antioxidant by same concentrations H
2O
2The maximum absorption wavelength of the gold nanoshell aqueous solution for preparing is designated as W; To not add antioxidant and H
2O
2The time same concentrations SiO
2The maximum absorption wavelength of/GNPs composite particles aqueous solution is designated as W
0, pass through formula
The antioxidant that calculates this concentration is to H
2O
2Clearance rate percentage;
4. calculate the antioxidant of gained to H according to step 3
2O
2The clearance rate numerical values recited, by increasing and/or reduce the concentration of antioxidant, obtain being no less than the antioxidant of 4 variable concentrations, respectively repeat steps 3, calculate under the variable concentrations antioxidant to H
2O
2Clearance rate, with resulting antioxidant to H
2O
2Clearance rate in minimum value be that lower limit, maximal value are the upper limit, constitute antioxidant to H
2O
2The clearance rate scope, if antioxidant is to H
2O
2The clearance rate scope can not cover the IC of antioxidant
50Value, i.e. antioxidant for clearing 50%H
2O
2Needed concentration, then repeating step 4, up to IC
50Value falls into antioxidant to H
2O
2The clearance rate scope;
5. the antioxidant that obtains according to step 3-step 4 is to H
2O
2The clearance rate data, adopt the ORIGIN mapping software, draw out H
2O
2The relation curve of clearance rate and corresponding antioxidant concentration, and to read clearance rate from figure be that the concentration of 50% o'clock antioxidant is c, unit is M, c is the IC of selected antioxidant
50Value is got inverse with c, and promptly 1/c is antioxidant for clearing H
2O
2The size of ability, unit is M
-1
Compared with prior art, the present invention has following advantage:
1. the present invention can finish under the operation of ultraviolet-visible spectrophotometer, and is easy and simple to handle, do not need complicated instrument and equipment.
2. do not relate to enzyme reaction in the experimental implementation process, experimental principle is clear and definite, does not also relate to poisonous and harmful carcinogen etc., can not produce any damaging effect for environment and human body.
3. experimental cost is low, and required reagent is the common reagent in laboratory, nano material easy to prepare, and single reaction only needs a few minutes to finish, and the running time is short.
4. among the present invention the plasmon resonance absorption peak wavelength of gold nanoshell is used for detection signal, with absorbance was compared as the method for optically measuring of detection signal in the past, spike length migrates near infrared region from visible region, the migration amount is big, detect sensitively more, detect the example as can be seen from Fig. 4 tannic acid of Figure of description, from the spectrum change of a~g, the spike length of absorption peak has been moved about 220nm, and the migration value of absorbance has only 0.523.
Since the peak wavelength change corresponding to the significant change of solution colour, and before with in the method for absorbance as detection signal, it is not obvious that solution colour changes, so this method also can be used in the visual qualitatively detection.
6. the present invention all is suitable for for water-soluble and fat-soluble antioxidant, and sensing range is extensive.
Embodiment
Embodiment 1
A kind of antioxidant for clearing H based on gold nanoshell
2O
2The assay method of ability, step is:
1. with gold nano grain and amidized SiO
2Colloidal solution mixes, stirs, and the amount of added gold nano grain should make gold nano grain at amidized SiO
2The coverage rate calculated value on bead surface is no less than 30%, and for example: present embodiment selects 30%, 50%, 70%, 90% respectively, and gold nano grain is adsorbed in amidized SiO by electrostatic adsorption
2Colloidal grain surface gets SiO
2/ GNPs composite particles aqueous solution is to SiO
2After/GNPs composite particles aqueous solution is carried out centrifugal treating, remove the gold nano grain that the upper strata is not adsorbed, again the SiO after removing the gold nano grain that is not adsorbed
2Add the pure water dilution in the/GNPs composite particles aqueous solution, and make precipitation be scattered in the SiO that obtains purifying in the pure water
2/ GNPs composite particles, SiO
2The SiO of/GNPs composite particles after dilution
2Concentration in the/GNPs composite particles aqueous solution is 2 * 10
10Individual/mL~2 * 10
12Individual/mL, for example, present embodiment is diluted to 2 * 10 respectively
10Individual/mL, 1 * 10
11Individual/mL, 5 * 10
11Individual/mL, 2 * 10
12Individual/mL;
2. in the phosphate buffered solution of 0.01M, add sal tartari and be 1% chlorauric acid solution as the stabilizing agent of reaction system and mass volume ratio concentration, phosphate buffered solution, the volume mL of sal tartari and chlorauric acid solution, quality mg, volume mL ratio is 20~500: 5~125: 0.3~7.5, for example, present embodiment is selected 20: 5: 0.3 respectively, 100: 25: 1.5,200: 75: 5,500: 125: 7.5, stir, in 4 ℃ of ageings 24h at least, for example, present embodiment is selected 24h respectively, 36h, 48h, 60h obtains the chlorauric acid solution that sal tartari is made stabilizing agent;
3. in the phosphate buffered solution of 0.01M, add antioxidant and H to be detected
2O
2, (antioxidant to be detected volumetric molar concentration in reaction system is 3 μ M~1200 μ M, and for example, present embodiment is selected 3 μ M, 200 μ M, 500 μ M, 1200 μ M, H respectively
2O
2Volumetric molar concentration in reaction system is 50 μ M~500 μ M, and for example, present embodiment is selected 50 μ M, 100 μ M, 200 μ M, 500 μ M respectively), phosphate buffered solution, antioxidant and H to be detected
2O
2Volume ratio be 0.6~15: 0.02~0.5: 0.04~1, for example, present embodiment is selected 0.6: 0.02: 0.04 respectively, 1: 0.1: 0.06,3: 0.2: 0.1,15: 0.5: 1, after mixing and reacting 1~5min, for example, present embodiment is selected 1min, 2min, 3min respectively, 5min is again to wherein adding SiO
2The sal tartari of/GNPs composite particles aqueous solution and step 2 gained is done the chlorauric acid solution of stabilizing agent, at this moment SiO
2The whole volumetric molar concentration of/GNPs composite particles in reaction system is 1.34 * 10
-11M~13.4 * 10
-11M, for example, present embodiment selects 1.34 * 10 respectively
-11M, 5 * 10
-11M, 10 * 10
-11M, 13.4 * 10
-11M, the whole volumetric molar concentration of gold chloride is 0.66 * 10
-4M~6.6 * 10
-4M, for example, present embodiment selects 0.66 * 10 respectively
-4M, 2 * 10
-4M, 4 * 10
-4M, 6.6 * 10
-4M, reaction 2~20min, for example, present embodiment is selected 2min respectively, 5min, 10min, 20min, remaining H
2O
2Gold chloride is reduced into gold nano grain and is deposited on SiO
2/ GNPs composite particles surface forms and coats incomplete gold nanoshell; The incomplete gold nanoshell of coating that above-mentioned reaction is formed characterizes under ultraviolet spectrophotometer, and record coats the maximum absorption wavelength of incomplete gold nanoshell aqueous solution, is designated as W
1In the time of will not adding antioxidant by same concentrations H
2O
2The maximum absorption wavelength of the gold nanoshell aqueous solution for preparing is designated as W; To not add antioxidant and H
2O
2The time same concentrations SiO
2The maximum absorption wavelength of/GNPs composite particles aqueous solution is designated as W
0, pass through formula
The antioxidant that calculates this concentration is to H
2O
2Clearance rate percentage;
4. calculate the antioxidant of gained to H according to step 3
2O
2The clearance rate numerical values recited, by increasing and/or reduce the concentration of antioxidant, obtain being no less than the antioxidant of 4 variable concentrations, respectively repeat steps 3, calculate under the variable concentrations antioxidant to H
2O
2Clearance rate, with resulting antioxidant to H
2O
2Clearance rate in minimum value be that lower limit, maximal value are the upper limit, constitute antioxidant to H
2O
2The clearance rate scope, between 0-100%, if antioxidant is to H
2O
2The clearance rate scope can not cover the IC of antioxidant
50Value, then repeating step 4, up to IC
50Value falls into antioxidant to H
2O
2The clearance rate scope;
5. the antioxidant that obtains according to step 3-step 4 is to H
2O
2The clearance rate data, adopt the ORIGIN mapping software, draw out H
2O
2The relation curve of clearance rate and corresponding antioxidant concentration, and to read clearance rate from figure be that the concentration of 50% o'clock antioxidant is c, unit is M, c is the IC of selected antioxidant
50Value is got inverse with c, and promptly 1/c is antioxidant for clearing H
2O
2The size of ability, unit is M
-1
Embodiment 2
1. the preparation of gold nano grain (GNPs)
Utilize the method for reduction gold chloride to prepare gold nano grain.The 1g gold chloride is dissolved in the 100mL pure water, gets 1% aqueous solution of chloraurate, 4 ℃ of refrigerations.Get the pure water of 200mL precooling, adding 3mL concentration and be 1% aqueous solution of chloraurate and 1mL concentration is the wet chemical of 0.2M, stirring and evenly mixing, again to wherein adding the sodium borohydride aqueous solution that 9mL concentration is 0.5mg/mL rapidly, mixed solution becomes claret by dark brown, promptly gets the gold nano grain of particle diameter about 5nm.Stir 10min again, the gold nano grain aqueous solution for preparing is placed 4 ℃ of stored refrigerated.
2.SiO
2The amination of colloid
Get the SiO that 40mL concentration is 0.013g/mL
2Alcosol, to the γ-An Jibingjisanyiyangjiguiwan that wherein adds 60 μ L (APTES), in 70 ℃ of following stirring reaction 3h, reaction places centrifuge tube with above-mentioned solution after finishing, and with the centrifugal 20min of 10000rpm, gets bottom SiO
2Solute adds the ultrasonic dispersion of absolute ethyl alcohol, and above step repeats 3 times, to remove unnecessary APTES.
3.SiO
2The preparation of/GNPs composite particles
Get the amidized SiO of 500 μ L
2Alcosol adds the dilution of 20mL absolute ethyl alcohol, with the SiO after the dilution
2Alcosol dropwise adds in the 200mL gold nano grain, and about 30min drips off, and constantly stirs, and electronegative gold nano grain is adsorbed in positively charged SiO by electrostatic interaction
2The bead surface forms SiO
2/ GNPs composite particles after continuing to stir 1h, places centrifuge tube with above-mentioned mixed liquor, with the centrifugal 20min of 3000rpm, gets bottom SiO
2/ GNPs composite particles adds the ultrasonic dispersion of pure water, and above step repeats 3 times, gets the SiO of purifying
2/ GNPs composite particles aqueous solution.
4.K
2CO
3/ HAuCl
4The preparation of mixed solution
Get the phosphate buffered solution that 100mL concentration is 0.01M, to wherein adding 25mg K
2CO
3, stir 10min, be 1% chlorauric acid solution to wherein adding 1.5mL concentration again, stir 20min and be placed on 4 ℃ of ageings and use behind the 24h at least.
5. forulic acid is removed H
2O
2The mensuration of ability
Get the phosphate buffered solution that 3mL concentration is 0.01M, to wherein adding 0.1mLH
2O
2With 0.2mL forulic acid, H
2O
2Final concentration in reaction system is 200 μ M, and the final concentration of forulic acid in reaction system is 3 μ M, stirs 2min, more respectively to wherein adding 0.5mL SiO
2/ GNPs composite particles aqueous solution and 3mL K
2CO
3/ HAuCl
4Mixed solution, reaction 5min, remaining H
2O
2Gold chloride is reduced into gold nano grain and is deposited on SiO
2/ GNPs composite particles surface forms and coats incomplete gold nanoshell.Reaction back solution characterizes with ultraviolet-visible spectrophotometer, and maximum absorption wavelength is designated as W
1The reference experiment replaces with the phosphate buffered solution that 0.2mL concentration is 0.01M with the forulic acid of 0.2mL, and all the other are constant, by same concentrations H
2O
2The maximum absorption wavelength of the gold nanoshell aqueous solution for preparing is designated as W.Control experiment is with the H of 0.1mL
2O
2Replace with the phosphate buffered solution that 0.3mL concentration is 0.01M with the forulic acid of 0.2mL, all the other are constant, record same concentrations SiO
2The maximum absorption wavelength of/GNPs composite particles aqueous solution is W
0Utilize formula
The forulic acid that calculates 3 μ M is to H
2O
2Clearance rate percentage be 14.3%.
Increase the concentration of forulic acid, make its final concentration in reaction system be respectively 5 μ M, 10 μ M, 50 μ M, 100 μ M.All the other operation stepss are the same, calculate 5 μ M, 10 μ M, and 50 μ M, the forulic acid of 100 μ M is to H
2O
2Clearance rate percentage be respectively 27.4%, 65.9%, 83.4%, 90.1%.
6. the variable concentrations forulic acid that obtains according to above-mentioned experiment is to H
2O
2The clearance rate data, adopt the ORIGIN mapping software, draw out H
2O
2The relation curve of clearance rate and corresponding forulic acid concentration, and to read clearance rate from figure be that the concentration of 50% o'clock forulic acid is 8 μ M, the i.e. IC of forulic acid
50Value is 8 μ M, with IC
50Value is got inverse, gets 12.5 * 10
-2μ M
-1, be forulic acid and remove H
2O
2The size of ability.
Embodiment 3
1. with embodiment 2 steps 1.
2. with embodiment 2 steps 2.
3. with embodiment 2 steps 3.
4. with embodiment 2 steps 4.
5. tartrate is removed H
2O
2The mensuration of ability
Selecting the final concentration of tartrate in reaction system is 1200 μ M, and all the other experimental implementation steps are with embodiment 2 steps 5, and the tartrate that calculates 1200 μ M is to H
2O
2Clearance rate percentage be 92.5%.Reduce tartaric concentration, make its final concentration in reaction system be respectively 800 μ M, 400 μ M, 200 μ M, 50 μ M.Repeat above operation steps, calculate 800 μ M, 400 μ M, 200 μ M, the tartrate of 50 μ M is to H
2O
2Clearance rate percentage be respectively 90.1%, 62.9%, 36.7%, 9.1%.
6. the variable concentrations tartrate that obtains according to above-mentioned experiment is to H
2O
2The clearance rate data, adopt the ORIGIN mapping software, draw out H
2O
2The relation curve of clearance rate and corresponding tartaric acid concentration, and to read clearance rate from figure be that 50% o'clock tartaric concentration is 273 μ M, promptly tartaric IC
50Be 273 μ M, with IC
50Value is got inverse, gets 0.36 * 10
-2μ M
-1, be tartrate and remove H
2O
2The size of ability.
Embodiment 4
1. with embodiment 2 steps 1.
2. with embodiment 2 steps 2.
3. with embodiment 2 steps 3.
4. with embodiment 2 steps 4.
5. citric acid is removed H
2O
2The mensuration of ability
Selecting the final concentration of citric acid in reaction system is 100 μ M, and all the other experimental implementation steps are with embodiment 2 steps 5, and the citric acid that calculates 100 μ M is to H
2O
2Clearance rate percentage be 48.7%.Increase, reduce the concentration of citric acid, make its final concentration in reaction system be respectively 400 μ M, 150 μ M, 20 μ M, 5 μ M.Repeat above operation steps, calculate 400 μ M, 150 μ M, 20 μ M, the citric acid of 5 μ M is to H
2O
2Clearance rate percentage be respectively 92.7%, 76.1%, 22.2%, 3.4%.
6. the variable concentrations citric acid that obtains according to above-mentioned experiment is to H
2O
2The clearance rate data, adopt the ORIGIN mapping software, draw out H
2O
2The relation curve of clearance rate and corresponding citric acid concentration, and to read clearance rate from figure be that the concentration of 50% o'clock citric acid is 106 μ M, the i.e. IC of citric acid
50Be 106 μ M, with IC
50Value is got inverse, gets 0.94 * 10
-2μ M
-1, be citric acid and remove H
2O
2The size of ability.
Embodiment 5
1. with embodiment 2 steps 1.
2. with embodiment 2 steps 2.
3. with embodiment 2 steps 3.
4. with embodiment 2 steps 4.
5. salicylic acid is removed H
2O
2The mensuration of ability
Selecting the final concentration of salicylic acid in reaction system is 10 μ M, and all the other experimental implementation steps are with embodiment 2 steps 5, and the salicylic acid that calculates 10 μ M is to H
2O
2Clearance rate percentage be 1.2%.Increase salicylic concentration, make its final concentration in reaction system be respectively 20 μ M, 50 μ M, 100 μ M, 200 μ M.Repeat above operation steps, calculate 20 μ M, 50 μ M, 100 μ M, the salicylic acid of 200 μ M is to H
2O
2Clearance rate percentage be respectively 3.2%, 7.6%, 12.3%, 21.8%.
Salicylic acid is to H
2O
2The clearance rate scope do not cover IC
50Value, continuing increases salicylic concentration, makes its final concentration in reaction system be respectively 400 μ M, 600 μ M, 800 μ M repeat above experimental implementation step, calculate 400 μ M, 600 μ M, the salicylic acid of 800 μ M is to H
2O
2Clearance rate percentage be respectively 45.3%, 68.7%, 90.5%.
6. the variable concentrations salicylic acid that obtains according to above-mentioned experiment is to H
2O
2The clearance rate data, adopt the ORIGIN mapping software, draw out H
2O
2The relation curve of clearance rate and corresponding salicylic acid concentration, and to read clearance rate from figure be that 50% o'clock salicylic concentration is 470 μ M, promptly salicylic IC
50Be 470 μ M, with IC
50Value is got inverse, gets 0.21 * 10
-2μ M
-1, be salicylic acid and remove H
2O
2The size of ability.
Embodiment 6
1. with embodiment 2 steps 1.
2. with embodiment 2 steps 2.
3. with embodiment 2 steps 3.
4. with embodiment 2 steps 4.
5. tannic acid is removed H
2O
2The mensuration of ability
Selecting the final concentration of tannic acid in reaction system is 200 μ M, and all the other experimental implementation steps are with embodiment 2 steps 5, and the tannic acid that calculates 200 μ M is to H
2O
2Clearance rate percentage be 88.1%.Reduce the concentration of tannic acid, make its final concentration in reaction system be respectively 100 μ M, 50 μ M, 25 μ M, 10 μ M.Repeat above operation steps, calculate 100 μ M, 70 μ M, 50 μ M, the tannic acid of 25 μ M is to H
2O
2Clearance rate percentage be respectively 87.5%, 86.2%, 85.2%, 79.1%.Tannic acid is to H
2O
2The clearance rate scope do not cover IC
50Be worth, continue to reduce the concentration of tannic acid, make its final concentration in reaction system be respectively 10 μ M, 5 μ M, 3 μ M repeat above experimental implementation step, calculate 10 μ M, 5 μ M, the tannic acid of 3 μ M is to H
2O
2Clearance rate percentage be respectively 64.7%, 53.3%, 38.6%.
6. the variable concentrations tannic acid that obtains according to above-mentioned experiment is to H
2O
2The clearance rate data, adopt the ORIGIN mapping software, draw out H
2O
2The relation curve of clearance rate and corresponding tannic acid concentration, and to read clearance rate from figure be that the concentration of 50% o'clock tannic acid is 7 μ M, the i.e. IC of tannic acid
50Be 7 μ M, with IC
50Value is got inverse, gets 14.28 * 10
-2μ M
-1, be tannic acid and remove H
2O
2The size of ability.
The checking example
1. the preparation of gold nano grain (GNPs)
Utilize the method for reduction gold chloride to prepare gold nano grain.The 1g gold chloride is dissolved in the 100mL pure water, gets 1% aqueous solution of chloraurate, 4 ℃ of refrigerations.Get the pure water of 200mL precooling, adding 3mL concentration and be 1% aqueous solution of chloraurate and 1mL concentration is the wet chemical of 0.2M, stirring and evenly mixing, again to wherein adding the sodium borohydride aqueous solution that 9mL concentration is 0.5mg/mL rapidly, mixed solution becomes claret by dark brown, promptly gets the gold nano grain of particle diameter about 5nm.Stir 10min again, the gold nano grain aqueous solution for preparing is placed 4 ℃ of stored refrigerated.
2.SiO
2The amination of colloid
Get the SiO that 40mL concentration is 0.013g/L
2Alcosol, to the γ-An Jibingjisanyiyangjiguiwan that wherein adds 60 μ L (APTES), in 70 ℃ of following stirring reaction 3h, reaction places centrifuge tube with above-mentioned solution after finishing, and with the centrifugal 20min of 10000rpm, gets bottom SiO
2Solute adds the ultrasonic dispersion of absolute ethyl alcohol, and above step repeats 3 times, to remove unnecessary APTES.
3.SiO
2The preparation of/GNPs composite particles
Get the amidized SiO of 500 μ L
2Alcosol adds the dilution of 20mL absolute ethyl alcohol, with the SiO after the dilution
2Alcosol dropwise adds in the 200mL gold nano grain, and about 30min drips off, and constantly stirs, and electronegative gold nano grain is adsorbed in positively charged SiO by electrostatic interaction
2The bead surface forms SiO
2/ GNPs composite particles after continuing to stir 1h, places centrifuge tube with above-mentioned mixed liquor, with the centrifugal 20min of 3000rpm, gets bottom SiO
2/ GNPs composite particles adds the ultrasonic dispersion of pure water, and above step repeats 3 times, gets the SiO of purifying
2/ GNPs composite particles aqueous solution.
4.K
2CO
3/ HAuCl
4The preparation of mixed solution
Get the phosphate buffered solution that 100mL concentration is 0.01M, to wherein adding 25mg K
2CO
3, stir 10min, be 1% chlorauric acid solution to wherein adding 1.5mL concentration again, stir 20min and be placed on 4 ℃ of ageings and use behind the 24h at least.
5. forulic acid is removed H
2O
2The mensuration of ability
Get the phosphate buffered solution that 3mL concentration is 0.01M, to wherein adding 0.1mLH
2O
2With 0.2mL forulic acid, H
2O
2Final concentration in reaction system is 200 μ M, and the final concentration of forulic acid in reaction system is followed successively by 3 μ M, 5 μ M, and 10 μ M, 50 μ M, 100 μ M stir 2min, more respectively to wherein adding 0.5mL SiO
2/ GNPs composite particles aqueous solution and 3mL K
2CO
3/ HAuCl
4Mixed solution, reaction 5min, remaining H
2O
2Gold chloride is reduced into gold nano grain and is deposited on SiO
2/ GNPs composite particles surface forms and coats incomplete gold nanoshell.Reaction back solution characterizes with ultraviolet-visible spectrophotometer, and maximum absorption wavelength is designated as W
1The reference experiment replaces with the phosphate buffered solution that 0.2mL concentration is 0.01M with the forulic acid of 0.2mL, and all the other are constant, by same concentrations H
2O
2The maximum absorption wavelength of the gold nanoshell aqueous solution for preparing is designated as W.Control experiment is with the H of 0.1mL
2O
2Replace with the phosphate buffered solution that 0.3mL concentration is 0.01M with the forulic acid of 0.2mL, all the other are constant, record same concentrations SiO
2The maximum absorption wavelength of/GNPs composite particles aqueous solution is W
0Utilize formula
Calculate 3 μ M, 5 μ M, 10 μ M, 50 μ M, the forulic acid of 100 μ M concentration is to H
2O
2Clearance rate percentage.
The pairing clearance rate percentage of each forulic acid concentration is utilized ORIGIN mapping software curve plotting, shown in forulic acid data and curves figure among Fig. 3 of Figure of description.But its corresponding detectable concentration scope, IC
50Value and H
2O
2Remove ability value shown in forulic acid data in the table 1.The IC of forulic acid
50Value and H
2O
2Remove ability value and be respectively 8 μ M and 12.5 * 10
-2μ M
-1
Existing a kind of employing peroxide oxalic acid lipid chemoluminescence method detects antioxidant for clearing H
2O
2The method of ability, this method detects principle and is: H
2O
2Can be under the effect of fluorophore the oxidation of a kind of fragrant oxalic acid lipoid substance be formed fragrant oxalic acid fat/fluorophore compound, in this process, give a kind of HEI with an electron transfer, then, this electronics is transferred to fluorophore again makes it be in a kind of high energy excited state, thereby produce the chemiluminescence phenomenon, luminous intensity can detect by fluorescence intensity, when containing antioxidant in the reaction system, and a part of H
2O
2Be eliminated, luminous intensity is suppressed.The forulic acid that utilizes this method to detect is removed 50%H
2O
2Needed concentration, i.e. IC
50Value is 10.37 μ M, H
2O
2Removing ability value is 9.7 * 10
-2μ M
-1Compare with our detection method, at first the detection principle of two kinds of detection methods is different, and it is luminous that existing method is based on chemi-excitation, and our method is based on the optical absorption characteristic of nano material; Secondly, concrete operations step and reaction conditions also are different fully, and the data that two kinds of methods draw can not be in full accord.Therefore, though final data result is variant, still within the variation range that experiment allows.The method that we are described is correct, effectively.
But table 16 kind of antioxidant detectable concentration scope, IC
50Value and H
2O
2Remove ability value
The contrast experiment:
1. this experimental technique: because we place SiO with the growth of gold nano grain
2The surface of bead has formed a kind of nano level nucleocapsid structure, and in the growth course of gold nano grain, except the variation of absorbance, wavelength also moves in the hundreds of nanometer range, and we adopt wavelength change as optical detector signal first, work as H
2O
2When the final concentration in reaction system changed between 0-200 μ M, wavelength had moved about 220nm, the H of promptly every variation 1 μ M
2O
2Concentration, the about 1.1nm of wavelength variations, during the parameter of general ultraviolet-visible spectrophotometer was provided with, the I of the resolution of wavelength reached 0.1nm, that is to say to be the H that can tell per 1 μ M fully if adopt wavelength as detection signal
2O
2The caused wavelength variations value of concentration.
2. existing method: with the gold nano grain for preparing as seed in solution for continuous growth, also adopt H
2O
2As the reductive agent of reaction system, existing method as optical detector signal, is worked as H with the variation of absorbance in the gold nano grain growth course in the experimental implementation
2O
2When the final concentration in reaction system changed between 0-600 μ M, it is about 0.55 that absorbance has changed, the H of promptly every variation 1 μ M
2O
2Concentration, the absorbance changing value is about 0.00092, and during the parameter of general ultraviolet-visible spectrophotometer was provided with, the I of the resolution of absorbance reached 0.001, that is to say to be the H that can't tell per 1 μ M if adopt absorbance as detection signal
2O
2The caused absorbance changing value of concentration.