A bacterial membrane-targeting fluorescent carbon dot-drug complex and a preparation method thereof

Abstract

The present application relates to the field of molecular imaging and oral and maxillofacial surgery, and specifically provides a kind of biofilm targeted fluorescent carbon dot-drug complex and a preparation method thereof, the complex is formed by the covalent connection of fluorescent carbon dot with carboxyl functionalization on the surface and amino-containing antibacterial drug through amide bond.The complex can specifically bind to bacterial biofilm (biofilm), and after binding, the fluorescence intensity significantly attenuates, thereby reflecting the clearance degree or distribution state of biofilm in real time.Meanwhile, the complex targets and enriches the drug in jaw lesion.The present application solves the problems of lack of targeting in the existing bone marrow infection flushing drug treatment, inability to assess bacterial clearance effect in real time, and easy to cause antibiotic abuse and drug resistance.

Description

Technical Field

[0001] This invention relates to the fields of molecular imaging and oral and maxillofacial surgery, specifically to a bacterial film-targeted fluorescent carbon dot-drug complex and its preparation method. Background Technology

[0002] Osteomyelitis of the jaw is an inflammatory and destructive disease of bone tissue caused by bacterial infection. Common pathogens include Staphylococcus aureus and Actinomycetes. However, due to the complex structure of the jawbone, relatively poor blood supply, and the formation of bacterial biofilms, conventional drugs often fail to achieve effective concentrations at the lesion site. In recent years, fluorescent carbon dots, as a novel nanomaterial, have been widely used in bioimaging and drug delivery due to their excellent photostability, biocompatibility, and surface modifiability. However, the covalent binding of the fluorescence monitoring function of carbon dots with antibacterial drugs (such as levofloxacin and vancomycin) to form chemical complexes has not yet been reported. Summary of the Invention

[0003] The purpose of this invention is to provide a bacterial film-targeting fluorescent carbon dot-drug complex that can selectively enrich therapeutic drugs in the bacterial film region and reflect the bacterial distribution in real time and non-invasively through changes in fluorescence intensity.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A biofilm-targeting fluorescent carbon dot-drug complex, wherein the complex is composed of fluorescent carbon dots and an antibacterial drug linked by covalent bonds; the surface of the fluorescent carbon dots is rich in carboxyl groups, the antibacterial drug molecule contains at least one primary or secondary amino group, and the fluorescent carbon dots and the antibacterial drug are coupled by amide bonds.

[0005] A further preferred embodiment is that the fluorescent carbon dots are prepared by a hydrothermal method using citric acid and ethylenediamine as precursors; the particle size of the fluorescent carbon dots is 2 nm to 10 nm, and they emit blue fluorescence at a wavelength of 450 nm when excited at a wavelength of 360 nm, with a surface carboxyl group density of 0.5 mmol / g to 2.0 mmol / g.

[0006] A further preferred embodiment is that the antibacterial drug is selected from at least one of levofloxacin, vancomycin, polymyxin B, pentoxifylline, and teriparatide.

[0007] A further preferred embodiment is that the antibacterial drug is levofloxacin, and the piperazine ring secondary amino group in the levofloxacin structure is coupled to the carboxyl group of the fluorescent carbon dot via an amide bond.

[0008] A further preferred embodiment is that the composite has the structural features shown in formula (1): CDs-CO-NH-LVX (1) CDs represents the fluorescent carbon dots, and LVX represents levofloxacin residues.

[0009] A further preferred embodiment is that the molar ratio of the fluorescent carbon dots to the antibacterial drug is 1:5 to 1:20.

[0010] A method for preparing a drug complex includes the following steps: (a) Preparation of surface carboxylated fluorescent carbon dots: Citric acid and ethylenediamine were dissolved in deionized water and subjected to a hydrothermal reaction at 200 °C for 6 hours. The mixture was then purified by dialysis to obtain surface carboxylated fluorescent carbon dots. (b) Activation of carboxyl groups: The carboxyl groups of the fluorescent carbon dots obtained in step (a) were activated using 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide; (c) Coupling reaction: Add the antibacterial drug to the system obtained in step (b), stir at room temperature for 12 hours, then remove the unreacted drug by dialysis, and freeze-dry to obtain the drug complex.

[0011] The antibacterial drug mentioned in step (c) is levofloxacin.

[0012] A further preferred embodiment is that the molecular structure of the drug complex is... Represented by the molecular formula: C 18 H 20 FN3O4 In this context, F represents a fluorine atom, OH represents a hydroxyl group, and -COOH represents a carboxyl group.

[0013] The advantages of this invention are: 1. In this invention, the carboxyl groups on the carbon dot surface form stable amide bonds with the amino groups of the drug, and the complex is not easily dissociated under physiological conditions, thus ensuring targeted delivery.

[0014] 2. The positively charged (or amphoteric) surface of the carbon dots of this invention can electrostatically adsorb negatively charged extracellular polymeric substances from the bacterial membrane.

[0015] 3. The complex of the present invention has good biocompatibility. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the synthetic route and structure of the fluorescent carbon dot-levofloxacin complex in this invention.

[0017] Figure 2 This is a comparison of the fluorescence spectra of the complex before and after binding with the Staphylococcus aureus biofilm in this invention.

[0018] Figure 3 This is a fluorescence imaging image showing the targeted enrichment of the complex of the present invention in an animal model infected with bacterial film.

[0019] Figure 4 This is a molecular structure diagram of the drug complex of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments. Simple equivalent substitutions, changes in size and material made by those skilled in the art based on this solution all fall within the scope of protection of this application.

[0021] like Figure 1-4 As shown, a bacterial film-targeting fluorescent carbon dot-drug complex is disclosed, wherein the complex is composed of fluorescent carbon dots and an antibacterial drug connected by covalent bonds; the surface of the fluorescent carbon dots is rich in carboxyl groups (-COOH), the antibacterial drug molecule contains at least one primary amino group (-NH2) or secondary amino group, and the fluorescent carbon dots and the antibacterial drug are coupled by amide bonds (-CO-NH-).

[0022] The fluorescent carbon dots are prepared by a hydrothermal method using citric acid and ethylenediamine as precursors. The particle size of the fluorescent carbon dots is 2 nm to 10 nm, and they emit blue fluorescence at a wavelength of 450 nm when excited at a wavelength of 360 nm. The surface carboxyl group density is 0.5 mmol / g to 2.0 mmol / g.

[0023] The antibacterial drug is selected from at least one of levofloxacin, vancomycin, polymyxin B, pentoxifylline, and teriparatide.

[0024] The antibacterial drug is levofloxacin, and the piperazine ring secondary amino group in the structure of levofloxacin is coupled to the carboxyl group of the fluorescent carbon dot via an amide bond.

[0025] The complex has the structural features shown in formula (I): CDs-CO-NH-LVX (I) CDs represents the fluorescent carbon dots, and LVX represents levofloxacin residues.

[0026] The molar ratio of the fluorescent carbon dots to the antibacterial drug is 1:5 to 1:20.

[0027] A method for preparing the drug complex includes the following steps: (a) Preparation of surface carboxylated fluorescent carbon dots: Citric acid and ethylenediamine were dissolved in deionized water and subjected to a hydrothermal reaction at 200 °C for 6 hours. The mixture was then purified by dialysis to obtain surface carboxylated fluorescent carbon dots. (b) Activation of carboxyl groups: The carboxyl groups of the fluorescent carbon dots obtained in step (a) were activated using 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS); (c) Coupling reaction: Add the antibacterial drug to the system obtained in step (b), stir at room temperature for 12 hours, then remove the unreacted drug by dialysis, and freeze-dry to obtain the drug complex.

[0028] The key chemical reaction is: CDs-COOH+LVX-NH2→CDs-CO-NH-LVX+ H2O.

[0029] The antibacterial drug mentioned in step (c) is levofloxacin.

[0030] The molecular structure of the drug complex Represented by the molecular formula: C 18 H 20 FN3O4 In this context, F represents a fluorine atom, OH represents a hydroxyl group, and -COOH represents a carboxyl group.

Claims

1. A bacterial film-targeted fluorescent carbon dot-drug complex, characterized in that, The complex is composed of fluorescent carbon dots and an antibacterial drug linked by covalent bonds; the surface of the fluorescent carbon dots is rich in carboxyl groups, the antibacterial drug molecule contains at least one primary or secondary amino group, and the fluorescent carbon dots and the antibacterial drug are coupled by amide bonds.

2. The bacterial film-targeted fluorescent carbon dot-drug complex according to claim 1, characterized in that, The fluorescent carbon dots are prepared by hydrothermal method using citric acid and ethylenediamine as precursors; the particle size of the fluorescent carbon dots is 2 nm to 10 nm, and they emit blue fluorescence at a wavelength of 450 nm when excited at a wavelength of 360 nm, with a surface carboxyl group density of 0.5 mmol / g to 2.0 mmol / g.

3. The bacterial film-targeted fluorescent carbon dot-drug complex according to claim 1, characterized in that, The antibacterial drug is selected from at least one of levofloxacin, vancomycin, polymyxin B, pentoxifylline, and teriparatide.

4. The bacterial film-targeted fluorescent carbon dot-drug complex according to claim 3, characterized in that, The antibacterial drug is levofloxacin, and the piperazine ring secondary amino group in the structure of levofloxacin is coupled to the carboxyl group of the fluorescent carbon dot via an amide bond.

5. The bacterial film-targeted fluorescent carbon dot-drug complex according to claim 4, characterized in that, The complex has the structural features shown in formula (1): CDs-CO-NH-LVX (1) CDs represents the fluorescent carbon dots, and LVX represents levofloxacin residues.

6. A bacterial film-targeted fluorescent carbon dot-drug complex according to any one of claims 1 to 5, characterized in that, The molar ratio of the fluorescent carbon dots to the antibacterial drug is 1:5 to 1:

20.

7. A method for preparing a pharmaceutical complex, used to prepare the complex according to any one of claims 1 to 6, characterized in that, Includes the following steps: (a) Preparation of surface carboxylated fluorescent carbon dots: Citric acid and ethylenediamine were dissolved in deionized water and subjected to a hydrothermal reaction at 200 °C for 6 hours. The mixture was then purified by dialysis to obtain surface carboxylated fluorescent carbon dots. (b) Activation of carboxyl groups: The carboxyl groups of the fluorescent carbon dots obtained in step (a) were activated using 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide; (c) Coupling reaction: Add the antibacterial drug to the system obtained in step (b), stir at room temperature for 12 hours, then remove the unreacted drug by dialysis, and freeze-dry to obtain the drug complex.

8. The preparation method according to claim 7, characterized in that, The antibacterial drug mentioned in step (c) is levofloxacin.

9. The bacterial film-targeted fluorescent carbon dot-drug complex according to claim 1, characterized in that, Drug complex molecular structure Represented by the molecular formula: C 18 H 20 FN3O4 In this context, F represents a fluorine atom, OH represents a hydroxyl group, and -COOH represents a carboxyl group.

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