CN103523772A

CN103523772A - Method for calcining and synthesizing graphene/carbon quantum dot

Info

Publication number: CN103523772A
Application number: CN201310357910.0A
Authority: CN
Inventors: 黄承志; 刘春芳; 高铭萱
Original assignee: Southwest University
Current assignee: Southwest University
Priority date: 2013-08-16
Filing date: 2013-08-16
Publication date: 2014-01-22
Anticipated expiration: 2033-08-16
Also published as: CN103523772B

Abstract

The invention discloses a method for calcining and synthesizing a graphene/carbon quantum dot. The method comprises the steps of 1, placing fullerene (C60) and sodium hydroxide (NaOH) into an agate mortar according to the mass ratio, porphyrizing and uniformly mixing; 2, transferring the reactants into a clean crucible, and calcining the reactants in a muffle furnace for 4+/-0.1h; 3, after the reaction is ended, taking out the reactants, cooling the reactants to the room temperature, adding ultrapure water to dissolve the obtained solid, and then, centrifuging for removing large-grained unreacted substances; 4, adding water to dialyse a supernatant liquor by using a dialysis bag until the pH is neutral, wherein the supernatant liquor is obtained through centrifuging; 5, carrying out freeze drying treatment on the dialysed solution to obtain yellow brown powder to obtain the graphene/carbon quantum dot. The method for calcining and synthesizing is simple in process and free of subsequent modification steps.

Description

The method of calcining synthetic graphite olefinic carbon quantum dot

Technical field

The present invention relates to nano material technology.

Background technology

Soccerballene (C ₆₀), since being found by scientist from 1985, be successfully applied to photoelectric device, organic photoelectric pond, biotechnology etc.But the fluorescence of soccerballene is very weak, bibliographical information its fluorescence quantum yield in the scope of 620-900 nm is only 10 ^-4.And the poorly soluble problem of soccerballene has also further limited its application aspect biological medicine.Although existing relevant report be take soccerballene as carbon source synthetic graphite olefinic carbon quantum dot, its building-up process is special, needs expensive instrument, or quantum yield lower (being less than 1%), therefore can not be widely used.

For above problem, by simple method, prepare that to can be used for the novel graphite olefinic carbon quantum dot that iron ion in cell detects be to have very important significance.

Summary of the invention

For passing through now the lower shortcoming of fullerenes synthesis graphite olefinic carbon point quantum yield, the object of the invention is by the synthetic novel graphite olefinic carbon quantum dot that can be used for iron ion detection in cell of simple calcination method single stage method, the method is simple to operate, synthesis step only has a step, and does not need complicated aftertreatment.

Technical scheme of the present invention is as follows:

The method of calcining synthetic graphite olefinic carbon quantum dot, step is as follows:

Step 1: by soccerballene (C ₆₀) put into agate mortar porphyrize and mix with sodium hydroxide (NaOH); Described soccerballene (C ₆₀) with sodium hydroxide (NaOH) 1:24 to 1:26 in mass ratio.

Step 2: above reactant is all transferred in clean crucible, adopts the crucible of 25 mL, calcine in retort furnace; Described calcining temperature is 350 ± 15 ℃, and calcination time is 4 ± 0.1 hours.

Step 3: after question response completes, take out gained solid cooled to room temperature, then add ultrapure water to dissolve gained solid, then centrifugal, get supernatant liquor stand-by;

Step 4: it is neutral with dialysis tubing, centrifugal gained supernatant liquor being carried out water to dialyse to pH; Centrifugal speed is 12000 rpms.The molecular weight cut-off of described dialysis tubing is 1000.

Step 5: the solution after dialysis is processed and obtained brown color powder by lyophilize, obtain graphite olefinic carbon quantum dot.

Described graphite olefinic carbon quantum dot is monodispersed uniform spherome, and size is 2-3 nm, and brilliant pitch is from being 0.24 nm; Described graphite olefinic carbon quantum dot height is 2.5 ± 1.5 nm, and carboxyl and hydroxyl are contained in surface, and maximum excitation wavelength is 290 nm, and maximum emission wavelength is 400 nm, and emission wavelength red shift with the red shift of excitation wavelength, and its quantum yield is about 4.8%; Described graphite olefinic carbon quantum dot has good biocompatibility, and its fluorescence can, by iron ion quencher, have the effect that detects iron ion in cell.

The present invention utilizes the synthetic method of calcining, has synthesized graphite olefinic carbon quantum dot simple and easy to getly, and has not needed follow-up modification step.The particle diameter of this carbon point is approximately 2-3 nm, and quantum yield can reach 4.8 %.

Can predict, this unique character may be more widely used aspect energy transfer and cell imaging.

Accompanying drawing explanation

Fig. 1 is that transmission electron microscope and high-resolution-ration transmission electric-lens characterize the pattern of carbon point, and histogram is the size distribution figure that in statistical graph, particle obtains.(A) the TEM imaging of graphene quantum dot, embedded figure: the HRTEM imaging of graphene quantum dot; (B) the particle diameter statistical Butut of graphene quantum dot.

Fig. 2 is the sign of atomic force microscope to carbon point height.Left figure is visual image (AFM imaging), and right figure is the height-change chart of red and green two the line area-covereds of above figure.

Fig. 3 is the fluorescence quantum yield mensuration figure (take Quinine Sulphate Di HC as standard, linear fit carbon is selected the quantum yield with Quinine Sulphate Di HC) of graphene quantum dot.

The spectral signature of Fig. 4 graphene quantum dot.(a) ultra-violet absorption spectrum of the graphene quantum dot aqueous solution (ABS); excitation spectrum (PLE) (emission wavelength is 400 nm) and emmission spectrum (PL) (excitation wavelength is 290 nm), embedded figure: the graphene quantum dot aqueous solution is the photo on (right side) under (left side) and 365 nm ultraviolet lamps under natural light respectively; (b) emmission spectrum of graphene quantum dot under different excitation wavelengths, embedded figure: the emmission spectrum of the graphene quantum dot of normalized under different excitation wavelengths.

Fig. 5 is that acquired results is the mean value of three average experiments with the graphene quantum dot of CCK-8 method research different concns and the cytotoxicity experiment of A549 cytosis.

Fig. 6 is that external use graphene quantum dot detects Fe ³⁺.(a) GQDs and different concns Fe ³⁺fluorescence spectrum figure after effect, from top to bottom, Fe ³⁺concentration is followed successively by: 0,0.02,0.1,0.2,0.4,0.6,0.8,1,2,4,6,

, embedded figure: Fe ³⁺concentration exists during scope 1- i/ i ₀with Fe ³⁺the graph of a relation of concentration; (b) impact of common metal ion on GQDs fluorescence, the concentration of metal ion is

.

Fig. 7 is A549 cell fluorescence co-focusing imaging figure; (A), (B) be respectively fluorescence imaging figure and light field and the fluorescence imaging stacking diagram of A549 cell; (C), (D) be respectively A549 cell with

gQDs is hatched fluorescence imaging figure and light field and the fluorescence imaging stacking diagram after 24h; (E), (F), (G), (H) for A549 cell is carried out to additional Fe3+ imaging analysis figure, A549 cell first with

gQDs is hatched 24h, and PBS washs after three times, then hatches fluorescence imaging figure and light field and the fluorescence imaging stacking diagram after 1h with the Fe3+ of different concns: (E, F) 0.02 mmol/L Fe ³⁺, (G, H) 0.1 mmol/L Fe ³⁺.

Embodiment

Embodiment 1:

Step 1: by 10.4 mg soccerballene (C ₆₀) put into agate mortar porphyrize and mix with 251.3mg sodium hydroxide (NaOH);

Step 2: by above reactant being all transferred in 25 clean mL crucibles, calcine 4.1 hours in 350 ± 15 ℃ of retort furnaces;

Step 3: after question response completes, take out and be cooled to room temperature, then add ultrapure water to dissolve gained solid, then centrifugal with 12000 rpms, remove lower sediment thing, get supernatant liquor stand-by;

Step 4: it is neutral that the dialysis tubing that is 1000 with molecular weight cut-off carries out water to dialyse to pH to centrifugal gained supernatant liquor;

Step 5: the solution after dialysis is processed and obtained brown color powder by lyophilize, obtain this graphite olefinic carbon quantum dot.

Embodiment 2:

Step 1: by 9.7mg soccerballene (C ₆₀) put into agate mortar porphyrize and mix with 248.9mg sodium hydroxide (NaOH);

Step 2: by above reactant being all transferred in 25 clean mL crucibles, calcine 4.0 hours in 348 ± 10 ℃ of retort furnaces;

Step 3-5 is identical with embodiment 1.

Below the signs such as pattern optical property (the product pattern that embodiment 1 obtains with 2 is all the same, both patterns, optics, chemical property is as broad as long) of product:

(1) morphology characterization: can find out by transmission electron microscope and high resolution projection Electronic Speculum, disperseing of this carbon point, does not have the situation of discovery aggregation.Its size is that size is about 2-3 nm, as shown in Figure 1 uniformly.By atomic force microscope, can find out that the height of carbon point is approximately 2.5 ± 1.5 nm, as shown in Figure 2, be roughly the thickness of 3-4 layer graphite.This shows, this carbon point is from meeting in person the feature of graphite olefinic carbon quantum dot.

(2) quantum yield: with Quinine Sulphate Di HC ( Φ _r=0.54) for standard substance, calculated the fluorescence quantum yield of this carbon point.Method of calculation are, quinine dissolution of solid, in the sulfuric acid of 0.1M, is measured to the absorption value of this solution on absorption spectrometer, for a ₁.Then in this absorption value of mensuration, be a ₁the fluorescence peak integral area of Quinine Sulphate Di HC solution, for i ₁.Repeat above step, obtain respectively the absorption value of four groups of different Quinine Sulphate Di HC solution a ₂, a ₃, a ₄with a ₅( a ₁, a ₂, a ₃, a ₄with a ₅value different between two, and maximum value is wherein not more than 0.7, minimum value is not less than 0.2), with and corresponding fluorescence intensity level i ₂, i ₃, i ₄with i ₅.Take absorption value as X-coordinate, and fluorescence peak integral area is that ordinate zou is mapped, the quantum yield typical curve that to obtain take Quinine Sulphate Di HC be standard.By above method, Quinine Sulphate Di HC solution is replaced with to carbon point solution, obtain carbon point quantum yield curve, as shown in Figure 4.Then according to formula

calculate, wherein Φfor the quantum yield of required carbon point, Φ _rfor the quantum yield of Quinine Sulphate Di HC standard substance, mfor stand quantum yield slope of a curve, m _rfor the slope of the Quinine Sulphate Di HC quantum yield typical curve that is standard, ηfor carbon, put the refractive index of solution environmental of living in, be the refractive index 1.33 of water, η _rfor the refractive index of Quinine Sulphate Di HC solution environment of living in, be also the refractive index 1.33 of water.The quantum yield that calculates this carbon point be 4.82%(as shown in Figure 3).Can find out, compare the quantum yield of existing other existing graphite olefinic carbon quantum dots that make by soccerballene, the quantum yield of this carbon point is higher.

(3) optical property: the absorption value that characterizes this carbon point by absorption can find that it goes out to have a wide acromion at 260 nm, has higher absorption value in 205 nm left and right.By observing the excitation-emission spectrum of this carbon point, its maximum excitation peak is at 290 nm places as seen, maximum emission peak 400 nm(Fig. 4 a), and emission peak wavelength changes with the change of excitation wavelength, as shown in the b of Fig. 4.

(4) material has character and purposes: this graphite olefinic carbon quantum dot has good biocompatibility.Take A549 cell as example, with CCK-8 laboratory method, carried out Cytotoxic experiment, can find out that in graphite olefinic carbon quantum dot concentration be in the scope of 5-40 μ g/mL time, the survival rate of cell, more than 80%, shows that it has lower bio-toxicity (Fig. 5).

By experiment in vitro, can prove, the fluorescence of this graphite olefinic carbon quantum dot can be preferably by iron ion quencher, and the concentration of quencher degree and iron ion exists linear relationship, and selectivity better (Fig. 6).

And first graphite olefinic carbon quantum dot and A549 cell are hatched 24 hours, then hatch again after 1 hour by the iron ion of additional different concns, can obviously observe blue-fluorescence by quencher (Fig. 7).

Result shows that graphite olefinic carbon quantum dot can successfully be applied to intracellular iron ion imaging analysis.

Claims

1. calcine a method for synthetic graphite olefinic carbon quantum dot, described method steps is as follows:

Step 1: by soccerballene (C ₆₀) put into agate mortar porphyrize and mix with sodium hydroxide (NaOH);

Step 2: above reactant is all transferred in clean crucible, calcines in retort furnace;

Step 4: it is neutral with dialysis tubing, centrifugal gained supernatant liquor being carried out water to dialyse to pH;

2. method according to claim 1, is characterized in that: described soccerballene (C ₆₀) with sodium hydroxide (NaOH) 1:24 to 1:26 in mass ratio.

3. method according to claim 1, is characterized in that: described calcining temperature is 350 ± 15 ℃, and calcination time is 4 ± 0.1 hours.

4. method according to claim 1, is characterized in that: the crucible that adopts 25 mL.

5. method according to claim 1, is characterized in that: described centrifugal speed is 12000 rpms.

6. method according to claim 1, is characterized in that: the molecular weight cut-off of described dialysis tubing is 1000.

7. the graphite olefinic carbon quantum dot detecting for iron ion in cell preparing according to the method described in any one of claim 1-6, it is characterized in that: described graphite olefinic carbon quantum dot is monodispersed uniform spherome, size is 2-3 nm, and brilliant pitch is from being 0.24 nm; Described graphite olefinic carbon quantum dot height is 2.5 ± 1.5 nm, and carboxyl and hydroxyl are contained in surface, and maximum excitation wavelength is 290 nm, and maximum emission wavelength is 400 nm, and emission wavelength red shift with excitation wavelength red shift, and its quantum yield is about 4.8%; Described graphite olefinic carbon quantum dot has good biocompatibility, and its fluorescence can be by iron ion quencher.

8. the application aspect the concentration of graphite olefinic carbon quantum dot claimed in claim 7 iron ion in detecting cell.