Amphiphilic carbon quantum dots with Janus structure and preparation method and application thereof

Abstract

The application relates to the technical field of carbon nanomaterial preparation, in particular to amphiphilic carbon quantum dots with a Janus structure and a preparation method and application thereof. Carboxyl-modified water-soluble carbon quantum dots are mixed with EDC and NHS in water to obtain an aqueous solution; octadecylamine is dissolved in an organic solvent to obtain an octadecylamine solution; then the octadecylamine solution is added to the aqueous solution, and an ultrasonic cell crusher is used for treatment, so that stable emulsion is formed while catalytic cross-linking is carried out; and the amphiphilic carbon quantum dots with the Janus structure are separated from the emulsion. The carbon quantum dots prepared by the application contain hydrophilic groups and oleophilic groups on the surface, and the surface distribution is in a Janus structure, so that the traditional carbon quantum dots are endowed with unique physical and chemical properties and functional attributes, and can be widely used in the fields of photocatalysis, biosensing, drug delivery, environmental detection and fine chemical industry.

Description

Technical Field

[0001] This invention relates to the field of carbon nanomaterial preparation technology, and in particular to an amphiphilic carbon quantum dot with a Janus structure, its preparation method, and its applications. Background Technology

[0002] Carbon quantum dots are carbon nanoparticles with a particle size in the nanometer range. They are a new type of fluorescent nanomaterial. In addition to having optical properties similar to those of traditional semiconductor quantum dots, they also have good environmental friendliness and biocompatibility. Therefore, they have broad research and application prospects in fields such as photocatalysis, biosensing, drug delivery, environmental monitoring and fine chemicals.

[0003] Currently, scholars have studied amphiphilic carbon quantum dots with different surface properties. Some researchers prepared amphiphilic carbon quantum dots with both carboxyl and alkyl groups on the surface by a one-step hydrothermal reaction of alkylamines with different chain lengths and citric acid [Yin Y, et al. Carbon, 2023.202:398-413]; others prepared lipophilic carbon quantum dots by microwave treatment of IPDI and further prepared them with hydrothermal treatment to produce carbon quantum dots with both hydrophilic and lipophilic properties [Jing T, et al. Journal of Materials Chemistry C, 2016.4:10146-10153]; still others prepared carbon quantum dots with both amine and siloxane groups on the surface by a one-step hydrothermal reaction of citric acid and siloxane [Naiqun Y, et al. Applied Surface Science. 2020.530:14724]. However, the number of reported amphiphilic carbon quantum dots is still relatively small, limiting the development of related fields and the potential applications of amphiphilic carbon quantum dots. Therefore, it is necessary to modify it and further explore its structure in order to expand its applications.

[0004] Janus particles are a novel class of materials that simultaneously possess two different surface properties, attracting widespread attention from researchers due to their unique surface microstructure and performance. There are many methods for preparing Janus particles, mainly including self-assembly, phase separation, solid matrix modification, and microfluidic methods. Compared to homogeneous nanoparticles of similar size, Janus nanoparticles exhibit higher interfacial activity, fully leveraging the surface efficiency of the material. Compared to traditional Janus particles, carbon quantum dots are even smaller, enabling them to exhibit superior interfacial activity and surface efficiency.

[0005] In view of this, it is necessary to provide an improved amphiphilic carbon quantum dot with a Janus structure, its preparation method, and its applications to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an amphiphilic carbon quantum dot with a Janus structure, its preparation method, and its application. Through the improvement of the preparation method, carbon quantum dots containing hydrophilic and lipophilic groups and with a Janus structure on the surface are obtained. These quantum dots have amphiphilic properties and also have higher interfacial activity, which can fully utilize the surface efficiency of the material.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing amphiphilic carbon quantum dots with a Janus structure, comprising the following steps:

[0008] S1. Water-soluble carbon quantum dots modified with carboxyl groups are mixed with EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide) and NHS (N-hydroxysuccinimide) in water to obtain an aqueous solution;

[0009] S2. Dissolve octadecylamine in an organic solvent to obtain an octadecylamine solution; then add it to the aqueous solution and process it using an ultrasonic cell disruptor to form a stable emulsion while catalyzing cross-linking.

[0010] S3. Amphiphilic carbon quantum dots with Janus structure are isolated from the emulsion.

[0011] This invention utilizes octadecylamine and carboxyl-modified water-soluble carbon quantum dots for amidation modification to achieve amphiphilicity. Simultaneously, a phase interface method is employed to impart a Janus structure to the surface of the modified carbon quantum dots. Ultrasonic cell disrupting is used to provide the necessary conditions for emulsion formation. Furthermore, the use of an EDC and NHS system ensures that amidation is carried out at relatively low temperatures, resulting in a stable emulsion. This prevents high-temperature reactions from affecting emulsion stability and the structure of the carbon quantum dots, thus guaranteeing the formation of the Janus structure.

[0012] Furthermore, the carboxyl source material of the carboxyl-modified water-soluble carbon quantum dots includes one or more of citric acid, malic acid, and oxalic acid, preferably citric acid-modified water-soluble carbon quantum dots;

[0013] And / or, the organic solvent includes one or more of benzene, toluene, xylene, and chloroform, preferably xylene. The mixture of the aqueous phase of carbon quantum dots and the oil phase of octadecylamine, formed by EDC and NHS systems and ultrasonic cell disruption, facilitates the amidation reaction between carbon quantum dots and octadecylamine at the interface.

[0014] Furthermore, in step S1, the concentration of the carboxyl-modified water-soluble carbon quantum dots in the aqueous solution is 1–100 g / L, preferably 1–10 g / L.

[0015] Furthermore, the mass ratio of EDC to NHS is (1.8 to 2.2):1, preferably 2:1.

[0016] Furthermore, the mass ratio of the carboxyl-modified water-soluble carbon quantum dots to EDC is 1:(0.1-10).

[0017] In step S1, it is preferable to use a stirring speed of 300±20 rpm for mixing.

[0018] Furthermore, in step S2, the volume ratio of the octadecylamine solution to the aqueous solution is (0.8-1.2):1, preferably 1:1.

[0019] Furthermore, in step S2, the concentration of the octadecylamine solution is 0.01–100 g / L, preferably 0.1–10 g / L.

[0020] Furthermore, in step S2, the processing time of the ultrasonic cell disruptor is 1–10 hours, preferably 3–8 hours; the temperature is 15–30°C, preferably 25°C. Under the catalytic action of EDC and NHS, this invention can reduce the amidation reaction temperature, preventing the high-temperature reaction from affecting the carbon quantum dot structure, and thus affecting the formation of the Janus structure.

[0021] Furthermore, the power of the ultrasonic cell disruptor is 240-600W, preferably 300W.

[0022] Further, step S3 includes: centrifuging the emulsion, drying the supernatant, dissolving it in deionized water, filtering, and dialyzing to obtain a pure aqueous solution of carbon quantum dots; then freeze-drying to obtain amphiphilic carbon quantum dots with a Janus structure.

[0023] Furthermore, the centrifugation speed is 3000-8000 r / min, and the time is 5±1 min; the clear liquid is the middle layer clear liquid after centrifugation; for example, the clear liquid at the bottom and the top 1-2 mm are removed respectively.

[0024] And / or, the filtration uses an aqueous phase filter membrane with a pore size of 0.22 μm;

[0025] And / or, the dialysis is performed using a dialysis bag of 500–1000D;

[0026] And / or, the freeze-drying temperature is -50 to -30°C.

[0027] As one specific embodiment of the present invention, the high-yield preparation method of the amphiphilic carbon quantum dots includes: mixing a citric acid-modified water-soluble carbon quantum dot aqueous solution with EDC / NHS to obtain a mixed solution; adding an octadecylamine xylene solution to the above mixed solution and sonicating it using a cell disruptor for 4-7 hours to obtain an emulsion; centrifuging, drying the middle layer, dissolving it in deionized water, filtering, and dialyzing to obtain a pure carbon quantum dot aqueous solution; then freeze-drying the obtained carbon quantum dot aqueous solution to obtain carbon quantum dots with a Janus structure.

[0028] Secondly, the present invention provides an amphiphilic carbon quantum dot with a Janus structure, which is prepared by any of the preparation methods described above.

[0029] Thirdly, this invention provides an application of amphiphilic carbon quantum dots with a Janus structure for photocatalysis, biosensing, drug delivery, environmental monitoring, and fine chemical industries.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. The present invention provides a method for preparing amphiphilic carbon quantum dots with a Janus structure. For the first time, this method utilizes a simple interfacial modification technique to prepare amphiphilic carbon quantum dots with a Janus morphology on the surface. Simultaneously, it exhibits higher interfacial activity, fully utilizing the surface efficiency of the material and endowing it with unique physicochemical properties and functional attributes. The prepared carbon quantum dots possess excellent dispersibility, amphiphilicity, and strong fluorescence, enabling applications in photocatalysis, biosensing, drug delivery, environmental monitoring, and fine chemicals.

[0032] 2. The preparation process of this invention is simple, the required instruments and equipment are simple and easy to operate, the process conditions are easy to achieve, the production cost is low, the application range is wide, and it is conducive to large-scale production. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 Transmission electron microscopy (TEM) image of the carbon quantum dots prepared in Example 1.

[0035] Figure 2 This is a particle size distribution diagram of the carbon quantum dots prepared in Example 1.

[0036] Figure 3The UV-Vis absorption spectrum and excitation and emission spectra of the carbon quantum dots prepared in Example 1 are shown.

[0037] Figure 4 The contact angles of the carbon quantum dots prepared in Example 1 were measured after being dissolved and dried in different solvents. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] Example 1

[0040] This embodiment provides a method for preparing amphiphilic carbon quantum dots with a Janus structure, including:

[0041] (1) Add 10 mg of citric acid-modified water-soluble carbon quantum dots to 10 g of deionized water, stir evenly, then add 20 mg of EDC and 10 mg of NHS and sonicate to obtain a mixed solution;

[0042] (2) Add 10g of 0.1% octadecylamine xylene solution to the mixed solution obtained in (1) above, and use an ultrasonic cell disruptor to sonicate for 6h to obtain an emulsion;

[0043] (3) Centrifuge the emulsion obtained in (2) at a speed of 8000 r / min for 5 min, take the middle emulsion layer, dry it, dissolve it with deionized water, filter it with a 0.22 μm filter membrane and collect the filtrate.

[0044] (4) Dialyze the filtrate obtained in step (3) using a dialysis bag with a capacity of 500-1000 μm.

[0045] D, the dialysate was obtained after 24 hours;

[0046] (5) The dialysate obtained in step (4) was freeze-dried at -40°C for 24 hours to obtain carbon quantum dots with Janus structure.

[0047] Figure 1 Transmission electron microscopy (TEM) images of the carbon quantum dots prepared in Example 1. Figure 1 It can be seen that the interplanar spacing is 0.21 nm, corresponding to the graphite (101) crystal plane.

[0048] Figure 2This is a particle size distribution diagram of the carbon quantum dots prepared in Example 1. As can be seen from the figure, the average particle size of the obtained carbon quantum dots is 3.5 nm.

[0049] Figure 3 The UV-Vis absorption and excitation / emission spectra of the carbon quantum dots prepared in Example 1 are shown. The results indicate that the optimal absorption wavelength is 375 nm and the emission wavelength is 465 nm.

[0050] Figure 4 The contact angles of the carbon quantum dots prepared in Example 1 were measured after being dissolved and dried in different solvents (deionized water in the left image and xylene in the right image). Specifically, a drop of 0.1 g / L carbon quantum dots was placed on a clean glass slide and then dried at 40°C for 24 h.

[0051] The results showed that the contact angle measured after dissolving in deionized water and then drying was 24°, indicating hydrophilicity, while the contact angle measured after dissolving in xylene and then drying was 105°, indicating lipophilicity. It can be seen that the membrane structure prepared by dissolving in different solvents exhibits different hydrophilicity and hydrophobicity, indicating that it has a Janus structure.

[0052] Example 2

[0053] This embodiment provides a method for preparing amphiphilic carbon quantum dots with a Janus structure, including:

[0054] (1) Add 10 mg of citric acid-modified water-soluble carbon quantum dots to 10 g of deionized water, stir evenly, add 20 mg of EDC and 10 mg of NHS and sonicate to obtain a mixed solution;

[0055] (2) Add 10g of 0.05% octadecylamine xylene solution to the mixed solution obtained in (1) above, and use a cell disruptor to sonicate for 6h to obtain an emulsion;

[0056] (3) Centrifuge the emulsion obtained in (2) at a speed of 8000 r / min for 5 min, take the middle layer, dry it, dissolve it in deionized water, filter it through a 0.22 μm filter membrane and collect the filtrate.

[0057] (4) Dialyze the filtrate obtained in step (3) using a dialysis bag with a capacity of 500-1000 μm.

[0058] D, the dialysate was obtained after 24 hours;

[0059] (5) The dialysate obtained in step (4) was freeze-dried at -40°C for 24 hours to obtain carbon quantum dots with Janus structure.

[0060] Example 3

[0061] This embodiment provides a method for preparing amphiphilic carbon quantum dots with a Janus structure, including:

[0062] (1) Add 10 mg of citric acid-modified water-soluble carbon quantum dots to 10 g of deionized water, stir evenly, add 20 mg of EDC and 10 mg of NHS and sonicate to obtain a mixed solution;

[0063] (2) Add 10g of 0.5% octadecylamine xylene solution to the mixed solution obtained in (1) above, and use a cell disruptor to sonicate for 6h to obtain an emulsion;

[0064] (3) Centrifuge the emulsion obtained in (2) at a speed of 8000 r / min for 5 min, take the middle layer, dry it, dissolve it in deionized water, filter it through a 0.22 μm filter membrane and collect the filtrate.

[0065] (4) Dialyze the filtrate obtained in step (3) using a dialysis bag with a capacity of 500-1000 μm.

[0066] D, the dialysate was obtained after 24 hours;

[0067] (5) The dialysate obtained in step (4) was freeze-dried at -40°C for 24 hours to obtain carbon quantum dots with Janus structure.

[0068] Example 4

[0069] This embodiment provides a method for preparing amphiphilic carbon quantum dots with a Janus structure, including:

[0070] (1) Add 10 mg of citric acid-modified water-soluble carbon quantum dots to 10 g of deionized water, stir evenly, add 40 mg of EDC and 20 mg of NHS and sonicate to obtain a mixed solution;

[0071] (2) Add 10g of 0.1% octadecylamine xylene solution to the mixed solution obtained in (1) above, and use a cell disruptor to sonicate for 6h to obtain an emulsion;

[0072] (3) Centrifuge the emulsion obtained in (2) at a speed of 8000 r / min for 5 min, take the middle layer, dry it, dissolve it in deionized water, filter it through a 0.22 μm filter membrane and collect the filtrate.

[0073] (4) Dialyze the filtrate obtained in step (3) using a dialysis bag with a specification of 500-1000D. After 24 hours, the dialysis solution is obtained.

[0074] (5) The dialysate obtained in step (4) was freeze-dried at -40°C for 24 hours to obtain carbon quantum dots with Janus structure.

[0075] Example 5

[0076] This embodiment provides a method for preparing amphiphilic carbon quantum dots with a Janus structure, including:

[0077] (1) Add 10 mg of citric acid-modified water-soluble carbon quantum dots to 10 g of deionized water, stir evenly, add 40 mg of EDC and 20 mg of NHS and sonicate to obtain a mixed solution;

[0078] (2) Add 10g of 0.2% octadecylamine xylene solution to the mixed solution obtained in (1) above, and use a cell disruptor to sonicate for 6h to obtain an emulsion;

[0079] (3) Centrifuge the emulsion obtained in (2) at a speed of 8000 r / min for 5 min, take the middle layer, dry it, dissolve it in deionized water, filter it through a 0.22 μm filter membrane and collect the filtrate.

[0080] (4) Dialyze the filtrate obtained in step (3) using a dialysis bag with a capacity of 500-1000 μm.

[0081] D, the dialysate was obtained after 24 hours;

[0082] (5) The dialysate obtained in step (4) was freeze-dried at -40°C for 24 hours to obtain carbon quantum dots with Janus structure.

[0083] Comparative Example 1

[0084] A method for preparing amphiphilic carbon quantum dots with a Janus structure includes:

[0085] (1) Add 10 mg of citric acid-modified water-soluble carbon quantum dots to 10 g of deionized water, stir evenly, and sonicate to obtain a mixed solution;

[0086] (2) Add 10g of 0.1% octadecylamine xylene solution to the mixed solution obtained in (1) above, and use an ultrasonic cell disruptor to sonicate for 6h to obtain an emulsion;

[0087] (3) Centrifuge the emulsion obtained in (2) at a speed of 8000 r / min for 5 min, take the middle layer, dry it, dissolve it in deionized water, filter it through a 0.22 μm filter membrane and collect the filtrate.

[0088] (4) Dialyze the filtrate obtained in step (3) using a dialysis bag with a capacity of 500-1000 μm.

[0089] D, the dialysate was obtained after 24 hours;

[0090] (5) The dialysate obtained in step (4) was freeze-dried at -40°C for 24 hours to obtain carbon quantum dots with Janus structure.

[0091] Comparative Example 2

[0092] A method for preparing amphiphilic carbon quantum dots with a Janus structure includes:

[0093] (1) Add 10 mg of citric acid-modified water-soluble carbon quantum dots to 10 g of deionized water, stir evenly, then add 20 mg of EDC and 10 mg of NHS and sonicate to obtain a mixed solution;

[0094] (2) Add 10g of 0.1% octadecylamine xylene solution to the mixed solution obtained in (1) above, and react for 6h to obtain an emulsion;

[0095] (3) Centrifuge the emulsion obtained in (2) at a speed of 8000 r / min for 5 min, take the middle layer, dry it, dissolve it in deionized water, filter it through a 0.22 μm filter membrane and collect the filtrate.

[0096] (4) Dialyze the filtrate obtained in step (3) using a dialysis bag with a capacity of 500-1000 μm.

[0097] D, the dialysate was obtained after 24 hours;

[0098] (5) The dialysate obtained in step (4) was freeze-dried at -40°C for 24 hours to obtain carbon quantum dots with Janus structure.

[0099] Table 1. Contact angle test results of Examples 1-5 and Comparative Examples 1-2

[0100]

[0101]

[0102] Experimental results show that in Comparative Example 1, without the addition of EDC and NHS, no intermediate emulsion layer appeared after centrifugation; in Comparative Example 2, without the use of a cell pulverizer, the intermediate emulsion layer was minimal after centrifugation, making it impossible to effectively separate the prepared Janus-shaped carbon quantum dots. The two comparative examples ultimately yielded mainly unreacted protocarboxyl-modified carbon quantum dots. Therefore, this invention, by adding EDC and NHS and using a cell pulverizer, facilitates the preparation of carbon quantum dots with a Janus structure.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing amphiphilic carbon quantum dots having a Janus structure, characterized by, The method comprises the following steps: S1, mixing carboxyl-modified water-soluble carbon quantum dots with EDC and NHS in water to obtain an aqueous solution, wherein the concentration of the carboxyl-modified water-soluble carbon quantum dots in the aqueous solution is 1-100 g / L, and / or the mass ratio of the EDC and the NHS is (1.8-2.2):1, and / or the mass ratio of the carboxyl-modified water-soluble carbon quantum dots and the EDC is 1:(0.1-10); S2, dissolving octadecylamine in an organic solvent to obtain an octadecylamine solution; then adding the octadecylamine solution into the aqueous solution, wherein the volume ratio of the octadecylamine solution and the aqueous solution is (0.8-1.2):1, and using an ultrasonic cell crusher to treat the mixture, so that the amino group of the octadecylamine and the carboxyl group of the carbon quantum dots are crosslinked by EDC and NHS, and a stable water-in-oil emulsion is formed by ultrasonic treatment, thereby introducing a hydrophobic long chain to a side region of the carbon quantum dots; S3, separating the Janus-structured amphiphilic carbon quantum dots from the emulsion; The carboxyl source of the carboxyl-modified water-soluble carbon quantum dots comprises one or more of citric acid, malic acid, and oxalic acid; The organic solvent comprises one or more of benzene, toluene, xylene, and chloroform.

2. The method for preparing amphiphilic carbon quantum dots with a Janus structure according to claim 1, characterized in that, The carboxyl source of the carboxyl-modified water-soluble carbon quantum dots is a citric acid-modified water-soluble carbon quantum dot.

3. The method for preparing amphiphilic carbon quantum dots with a Janus structure according to claim 1 or 2, characterized in that, In step S1, the concentration of the carboxyl-modified water-soluble carbon quantum dots in the aqueous solution is 1-10 g / L. And / or, the mass ratio of the EDC and the NHS is 2:

1. 4.The method of claim 1, wherein the method is characterized by, In step S2, the volume ratio of the octadecylamine solution and the aqueous solution is 1:

1.

5. The method for preparing amphiphilic carbon quantum dots with a Janus structure according to claim 1, characterized in that, In step S2, the concentration of the octadecylamine solution is 0.01-100 g / L.

6. The method for preparing amphiphilic carbon quantum dots with a Janus structure according to claim 5, characterized in that, In step S2, the concentration of the octadecylamine solution is 0.1-10 g / L.

7. The method for preparing amphiphilic carbon quantum dots with a Janus structure according to claim 1, characterized in that, In step S2, the treatment time of the ultrasonic cell crusher is 1-10 h, and the temperature is 15-30℃. And / or, the power of the ultrasonic cell crusher is 240-600 W. 8.The method of claim 7, wherein the method is characterized by, In step S2, the treatment time of the ultrasonic cell crusher is preferably 3-8 h. And / or, the power of the ultrasonic cell crusher is 300 W. 9.The method of claim 1, wherein the method is characterized by, Step S3 comprises: centrifuging the emulsion, drying the supernatant, dissolving the dried supernatant in deionized water, filtering, dialyzing, and obtaining a pure carbon quantum dot aqueous solution; and then freeze-drying to obtain the Janus-structured amphiphilic carbon quantum dots. 10.The method of claim 9, wherein the method is characterized by, The centrifugation is performed at a speed of 3000-8000 r / min for 5±1 min, and the supernatant is a middle layer supernatant after centrifugation. And / or, the filtering is performed using a water-phase filter membrane with a pore size of 0.22 um. And / or, the dialysis is performed using a dialysis bag with a molecular weight cutoff of 500-1000 D. And / or, the freeze-drying is performed at a temperature of -50 to -30℃.

11. An amphiphilic carbon quantum dot having a Janus structure, characterized by, The Janus-structured amphiphilic carbon quantum dots are prepared by the preparation method of any one of claims 1-10.

12. Use of the amphiphilic carbon quantum dots having a Janus structure according to claim 11, characterized in that, The Janus-structured amphiphilic carbon quantum dots are used in the fields of photocatalysis, biosensing, drug delivery, environmental detection, and fine chemical industry.

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