CN104709894A - Preparation method and applications of fluorescent carbon quantum dots - Google Patents

Abstract

The present invention discloses a preparation method and applications of fluorescent carbon quantum dots (Carbon dots, short for CDs). According to the preparation method, formic acid and bovine serum albumin (BSA) are adopted as raw materials, a molar ratio of the amino of the BSA to the aldehyde of the formic acid is 1:1, hydrothermal synthesis is performed, the aldehyde of the formic acid and the amino of the BSA are subjected to condensation to generate carbon nitrogen double bond, the generated polymer having the carbon nitrogen double bond self-reacts to generate carbon quantum dots, and a water-based membrane and a dextran G-25 gel column are used to separate and purify. According to the present invention, the carbon quantum dots prepared through the method have characteristics of small particle size, good light stability, wide excitation and emission spectrum range, high fluorescence quantum yield, low toxicity, and environmental protection, and can be successfully used in biological cell imaging, wherein the yield of the carbon quantum dots is generally low in the prior art is solved with the preparation method of the present invention.

Description

A kind of preparation method and application of fluorescent carbon quantum dot

Technical field

The present invention relates to fluorescent nano material, specifically a kind of Synthesis and applications of fluorescent carbon quantum dot.

Background technology

In recent years, along with the develop rapidly of nanotechnology, nano material (as: nano magnetic material, nano ceramic material, nano-sensor, nanometer FUNCTIONALLY GRADIENT MATERIAL, nano semiconductor material and nano catalytic material) is extensively familiar with by people and applies.At biological, field of medicaments, the preparations and applicatio of nano material also becomes meticulous gradually, and the quantum dot for biomarker is one wherein.Quantum dot, can be described as again nanocrystalline, is a kind of by II-VI group or the elementary composition nano particle of iii-v.Particle diameter is generally between 1 ~ 10nm, and because electronics and hole are by quantum confinement, continuous print energy band structure becomes the discrete energy levels structure with molecular characterization, can emitting fluorescence after being subject to excitation.The research of quantum dot be the nineties in 20th century the earliest from CdSe quantum dot, as fluorescent probe, it has much excellent character: one, emmission spectrum can be controlled by the size changing quantum dot; Two, good light stability; Three, excitation spectrum, emmission spectrum are narrow; Four, Stokes displacement is large; Five, good biocompatibility; Six, fluorescence lifetime is long.The quantum dot with above 6 character is almost a kind of desirable fluorescent probe, but quantum dot is made up of poisonous heavy metal element, toxicity limits its application in biological medicine, the carbon point (Carbon Dots) of low toxicity has arisen at the historic moment as a kind of new fluorescent probe, and carbon point is except possessing the exciting light spectrum width of quantum dot ¹, particle diameter is little ², good light stability ³, outside Stokes displacement is large, good biocompatibility, fluorescence lifetime are long advantageous property, also there is hypotoxic feature, so be seen as substitute (the document 1:Hu Shengliang of quantum dot in biomarker, Bai Peikang, Sun Jing, Cao Shirui, PROGRESS IN CHEM ISTRY, 2010,22:345-351.).

The Late Cambrian of carbon point be 2004 by the carbon nano-particles with photoluminescent property serendipitous when carbon nanotube prepared by purification arc process such as Xiaoyou Xu, fluorescence quantum yield is at that time very low.2006, scientist Sun and his colleagues of Clemson University prepare (document 2:Sheila N.Baker with laser ablation, Gary A.Baker, Angew.Chem.Int.Ed.2010,, and adopt organic reagent passivation 49,67266744), the method has synthesized the good product of fluorescence property, is called as carbon point first.2008, Wuhan University Pang etc. were carbon source with graphite, synthesize carbon quantum dot, occurred hydrothermal method and microwave method subsequently with electrochemical oxidation process.Along with the appearance of new preparation method, the fluorescence property of carbon point also being enhanced gradually, also becomes extensively in the application of medical science and biological field.But the quantum yield of carbon point is still very low, does not also reach the level of quantum dot, under such situation background, the preparation of the carbon point of high-fluorescence quantum yield seems particularly necessary.

Summary of the invention

For above problem, the object of this invention is to provide the preparation method and application of a kind of fluorescent carbon quantum dot (Carbon Dots).

To achieve these goals, the technical solution used in the present invention is:

Adopt hydrothermal method one-step synthesis fluorescent carbon quantum dot, preparation method is as follows: with bovine serum albumin (BSA) and formic acid for raw material, the mol ratio of the amino of BSA and the aldehyde radical of formic acid is 1:1, first the aldehyde radical of formic acid and the amino condensation of BSA generate carbon-to-nitrogen double bon, and the polymkeric substance id reaction with carbon-to-nitrogen double bon of generation generates fluorescent carbon quantum dot.

In the carbon dot structure of fluorescent carbon quantum dot, introduce carbon-to-nitrogen double bon, increase the conjugative effect between double bond, the polymkeric substance id reaction with carbon-to-nitrogen double bon generates the carbon nanoparticle with photoluminescent property, i.e. fluorescent carbon quantum dot.

BSA is dissolved in deionized water, dropwise formic acid is instilled in mixture subsequently in the deionized water being dissolved with BSA, rapid stirring, the solution mixing formic acid is put into hydrothermal reaction kettle, adopt heating device, temperature programming 1h, temperature of reaction 200 DEG C, reaction times 10h, product is yellow clear soln.

Described product dextran G-25 gel separator column separating-purifying, remove unreacted formic acid, after purifying, the gained carbon point aqueous solution is golden yellow liquid.

Described fluorescent carbon quantum dot is applied in biomarker.

With BSA and formic acid for raw material, under 200 DEG C of temperature programming conditions, the amino of BSA and the aldehyde radical generation condensation reaction of formic acid, (this reaction object introduces carbon-to-nitrogen double bon in carbon dot structure to generate carbon-to-nitrogen double bon, strengthen the conjugative effect between double bond in polymer architecture, to improve the fluorescence quantum yield of carbon point), the polymkeric substance with carbon-to-nitrogen double bon of generation, the polymkeric substance id reaction of this structure generates the carbon nanoparticle with photoluminescent property.Product dextran G-25 gel column separator column separating-purifying, the carbon point fluorescence quantum yield of gained is 17%.

The following advantage had of carbon point prepared by the present invention:

(1) preparation method is simple, and do not need loaded down with trivial details separation application, the carbon nano-particles particle diameter of synthesis is little, toxicity is low, good biocompatibility.

(2) fluorescence quantum yield is high, has up-conversion fluorescence.

(3), there is not photobleaching phenomenon in good light stability.

(4) fluorescence quantum yield of this carbon point is higher, can be used for living animal fluorescence imaging, carries out real-time, detection of dynamic.

Accompanying drawing explanation

Fig. 1 is the photo of carbon point under UV-irradiation;

Fig. 2 is the electron micrograph of carbon point;

Fig. 3 is the XPS figure of carbon point;

Fig. 4 is carbon swarming spectrogram in carbon point;

Fig. 5 is the infrared spectrogram of carbon point;

Fig. 6 is the ultraviolet spectrogram of carbon point;

Fig. 7 is the fluorescence spectrum figure of carbon point;

Fig. 8 is the cell imaging picture of carbon point.

Embodiment

Below by embodiment, the invention will be further described.

Embodiment 1

The preparation and characterization of carbon point:

(1) preparation of carbon point and separating-purifying:

First get BSA 0.9g, be dissolved in 20ml deionized water, then dropwise instill the formic acid 0.318g of 88%, with stirring, mixture is mixed, transfers in hydrothermal reaction kettle by the solution mixed, retort furnace heats, adopt temperature programming 1h, be warming up to 200 DEG C, the reaction times is 10h, and unreacted formic acid is removed in the separation and purification of products obtained therefrom dextran G-25 gel column, the gained carbon point aqueous solution is golden yellow liquid, afterwards by product lyophilize.

(2) measurement of the quantum yield of carbon point:

Choose Quinine Sulphate Di HC solution as reference sample, select formula to be:

In formula for quantum yield QY%, A are ultraviolet absorption value, I is fluorescence integrated emission intensity, for the refractive index of solvent, S is reference, and X is testing sample,

(3) property representation of carbon point character

The surface tissue of (a) carbon point and size dimension

Fig. 2 is the electron micrograph of carbon point, and even by the Carbon Dots size that this method is obtained as seen from photo, carbon point grain size is about 2nm.

Fig. 3 is the XPS figure of carbon point.As can be seen from the figure, a large amount of C is contained, O, N element in the surface of carbon point.

Fig. 4 is the XPS carbon swarming spectrogram of carbon point.As can be seen from the figure, in carbon dot structure, C=C structure is contained at 284.06eV place, at 286.8eV place containing C-N structure, at 288.05eV place containing C=O structure.

Fig. 5 is the infrared spectrogram of carbon point.As can be seen from the figure, at 3411cm ^-1and 2971cm ^-1the stretching vibration absorption peak of place containing N-H and C-H, at 1750cm ^-1to 1650cm ^-1containing the stretching vibration absorption peak of C=O and the flexural vibration absorption peak of C=N and N-H in scope, at 1346cm ^-1there is the stretching vibration absorption peak of C-N at place, at 1200cm ^-1stretching vibration charateristic avsorption band containing C-O.

The spectral response curve of (b) carbon point

Fig. 6 is the ultraviolet spectrogram of carbon point.N → π has been there is at 270nm place as seen in figure ^*the charateristic avsorption band of transition.

Fig. 7 is the fluorescence spectrum figure of carbon point, and the increase as seen along with excitation wavelength in figure, emmission spectrum generation red shift, emission maximum, at 330nm place, excites wide ranges.

(5) biologic applications of carbon point character

Fig. 8 is the cell dyeing photo of carbon point.Select the carbon point solution mark Tca-8113 Tca8113 cells of 1mg/ml concentration, can find out in figure, carbon point has successfully dyeed Tca-8113 Tca8113 cells, and fluorescence intensity is obviously better than blank group.

Claims (5)

1. a preparation method for fluorescent carbon quantum dot, is characterized in that:

Adopt hydrothermal method one-step synthesis fluorescent carbon quantum dot, preparation method is as follows: with bovine serum albumin (BSA) and formic acid for raw material, the mol ratio of the amino of BSA and the aldehyde radical of formic acid is 1:1, first the aldehyde radical of formic acid and the amino condensation of BSA generate carbon-to-nitrogen double bon, and the polymkeric substance id reaction with carbon-to-nitrogen double bon of generation generates fluorescent carbon quantum dot.

2. the preparation method of fluorescent carbon quantum dot according to claim 1, is characterized in that:

In the carbon dot structure of fluorescent carbon quantum dot, introduce carbon-to-nitrogen double bon, increase the conjugative effect between double bond, the polymkeric substance id reaction with carbon-to-nitrogen double bon generates the carbon nanoparticle with photoluminescent property, i.e. fluorescent carbon quantum dot.

3. the preparation method of fluorescent carbon quantum dot according to claim 2, is characterized in that:

BSA is dissolved in deionized water, dropwise formic acid is instilled in mixture subsequently in the deionized water being dissolved with BSA, rapid stirring, the solution mixing formic acid is put into hydrothermal reaction kettle, adopt heating device, temperature programming 1h, temperature of reaction 200 DEG C, reaction times 10h, product is yellow clear soln.

4. the preparation method of fluorescent carbon quantum dot according to claim 3, is characterized in that:

Described product dextran G-25 gel separator column separating-purifying, remove unreacted formic acid, after purifying, the gained carbon point aqueous solution is golden yellow liquid.

5. an application for the fluorescent carbon quantum dot described in any one claim described above, is characterized in that: described fluorescent carbon quantum dot is applied in biomarker.