Photo-response antibacterial gold-silver alloy cluster

Abstract

The invention discloses a light-response antibacterial gold-silver alloy cluster, and belongs to the crossing field of nanomaterial chemistry and biochemistry. According to the invention, levonorgestrel with good biocompatibility is taken as a protective ligand, and the alloy nano-cluster with excellent fluorescence performance and accurate atomic size is synthesized by a room-temperature volatilization one-pot method. The chemical formula of the nano alloy cluster is C255H330Au7Ag5O25 (abbreviated as Au7Ag5L12), the nano alloy cluster belongs to a hexagonal system, and the space group is a chiral space group P212121. The nano-alloy cluster has a smaller size (-2 nm) and good dispersity; the fluorescent probe has strong green fluorescence at room temperature, the fluorescence quantum yield is 47.9%, and the fluorescent probe has the potential for cell imaging. The nano-alloy cluster material can controllably generate active oxygen through photocatalysis, can efficiently destroy a bacterial membrane to cause bacterial death, and can avoid generation of bacterial drug resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the cross field of nanomaterial chemistry and biochemistry, and particularly relates to an atomically precise nanometer alloy cluster material for common bacteria removal, especially controllable antibiosis through photocatalytic response. BACKGROUND

[0002] Bacterial infection is a major global public health challenge, with an estimated 700,000 deaths worldwide each year. The main reason for the persistence of these infections is the formation of bacterial biofilms. Biofilms form a strong physical barrier against antibiotics, significantly enhancing the drug resistance of bacteria. The biggest problem currently faced by antibiotic drugs is drug resistance, and there is no good solution. The present application attempts to use photodynamic therapy to improve the drug resistance of antibiotic drugs, and to controllably release reactive oxygen species (ROS) from gold-silver alloy clusters under light to cause irreversible damage to bacterial biofilms, ultimately leading to bacterial death and avoiding the generation of bacterial drug resistance. The design idea is novel and there is no related report at present. SUMMARY

[0003] Therefore, the present application aims to provide a light-responsive atomically precise nanometer alloy cluster antibacterial agent.

[0004] To achieve the purpose of the present application, the chemical formula of the nanometer alloy cluster material is C 255 H 330 Au7Ag5O 25 , and is abbreviated as: Au7Ag5L 12 , which belongs to the hexagonal system; the space group is chiral space group P212121, a = 22.54480(10) , b = 34.1256(2) , c = 36.4447(2) , alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, V = 28038.9(3) The ligand L refers to levonorgestrel, and the molecular structural formula is as follows:

[0005] The nanometer alloy cluster material according to the present application is prepared by the following steps:

[0006] The ligand levonorgestrel and gold tetrahydrothiophene chloride are dissolved in dichloromethane (DCM), and the clear solution is stirred at room temperature; then triethylamine is added, and stirring is continued at room temperature; finally, silver nitrate acetonitrile solution is added, and stirring is carried out at room temperature. After the reaction is completed, the clear solution is placed at room temperature and volatilized in the dark to obtain crystals, which are filtered, washed, and dried at room temperature.

[0007] The nano-alloy cluster material is composed of 7 gold atoms, 5 silver atoms and 12 organic ligands Figure 1 As shown in the figure, the inner core is formed by six metal atoms through the interaction of metal bonds to form an octahedron, and the metals at both ends are connected to three metal atoms respectively, forming a 12-metal inner core cluster. The ligand is coordinated with the metal through the carbon atom on the terminal alkyne. Figure 2 As shown in the figure.

[0008] The nano-alloy cluster material has a super-small size (~ 2nm) and good dispersibility Figure 3 And 4 As shown in the figure, it has strong green fluorescence at room temperature, and the optimal emission wavelength position is 522nm (excitation wavelength 390nm); the fluorescence quantum yield is 47.9% at room temperature Figure 5 As shown in the figure). The photocatalytic alloy cluster is verified to produce active oxygen by 3,3',5,5'-tetramethylbenzidine as an indicator, and the active oxygen can destroy the bacterial membrane to cause bacterial death, avoiding the generation of bacterial drug resistance Figure 6 Under the condition of controllable light response, it shows excellent antibacterial performance, which can be clearly indicated by in vitro plate coating experiment Figure 7 Through SEM morphology shooting of bacteria, it can be further verified that the alloy cluster of the application destroys the integrity of the bacterial membrane by photocatalytic production of active oxygen, and finally causes bacterial death Figure 8

[0009] The nano-alloy cluster material has strong green fluorescence at room temperature, and has good dispersibility and good biocompatibility, has potential for cell imaging, and can controllably and efficiently kill bacteria under light as an antibacterial agent. The strategy for developing new type of high-efficiency photocatalytic alloy cluster material provides a new idea, which has important value in efficient antibacterial and anti-infection treatment. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is a single crystal structure diagram of the nano-alloy cluster material of the application. Figure 2 It is a core structure and ligand coordination mode diagram of the nano-alloy cluster material of the application. Figure 3 It is a transmission electron microscope image of the nano-alloy cluster material of the application. Figure 4 It is a dynamic light scattering diagram of the nano-alloy cluster material of the application. Figure 5 It is an excitation curve and emission curve diagram of the nano-alloy cluster material of the application, and a fluorescence photo diagram of the material under 365nm excitation. Figure 6 ​The ultraviolet-visible spectrum of the nanometer alloy cluster material catalyzing the oxidation of TMB. Figure 7 The in vitro coating antibacterial effect diagram of the nanometer alloy cluster material of the application on escherichia coli and staphylococcus aureus. Figure 8 The scanning electron microscope image of escherichia coli and staphylococcus aureus treated by the nanometer alloy cluster material of the application. DETAILED DESCRIPTION

[0011] The application will be further described below by examples:

[0012] Example 1: Synthesis of the nanometer alloy cluster material of the application

[0013] The ligand levonorgestrel and gold tetrahydrothiophene chloride were dissolved in dichloromethane (DCM), and the clear solution was stirred at room temperature. Then triethylamine was added, and the stirring was continued at room temperature. Finally, silver nitrate acetonitrile solution was added, and the stirring was continued at room temperature for 1 h. After the reaction was completed, the reaction liquid was placed at room temperature and volatilized in the dark. After 2-3 days, green block crystals were obtained. The crystals were filtered, washed with acetonitrile, and dried at room temperature.

[0014] The nanometer alloy cluster material of the application prepared in Example 1 was further characterized, and the process was as follows: (1) Crystal structure determination X-ray diffraction measurement of the single crystal Au7Ag5L was carried out at 200 K using a Rigaku XtaLAB Pro diffractometer (Cu-Ka radiation, λ = 1.54184 ). 12 Data collection and recovery were carried out by the program CrysAlisPro. The structure was solved by the internal phase method (SHELXT-2015), and the full matrix least squares refinement of F2 was carried out by OLEX2. The SHELXL-2018 / 3 module was used. The solvent molecules were processed by the mask program in OLEX2. All non-hydrogen atoms were refined by the anisotropic thermal parameter method. All hydrogen atoms were included in the ideal position. The detailed crystal determination data are shown in Table 1; the important bond length data are shown in Table 2.

[0015] Table 1 Main crystallographic data of the nanometer alloy cluster material of the application R1 = ∑||F o |-|F c | / ∑||F o |.wR2 = [∑w(F o 2 -F c 2 ) 2 / ∑w(F o2 2 1 / 2 Table 2 Au7Ag5 Important bond lengths

[0016] The above embodiments are only used to illustrate the technical solutions of the present application, and the present application has other embodiments in addition to the above. However, any technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope of the present application.​​

Claims

1. A nano-alloy cluster material, characterized in that: Its chemical formula is: C 255 H 330 Au7Ag5O 25 Abbreviated as: Au7Ag5L 12 , belongs to hexagonal system; space group is chiral space group P212121, α = 90°, β = 90°, γ = 90°, The ligand L refers to levonorgestrel, whose molecular structure is as follows:

2. The nanocluster alloy material of claim 1, wherein: It consists of 7 gold atoms, 5 silver atoms and 12 organic ligands. The core is formed by the interaction of six metal atoms through metallic bonds to form an octahedron. The metals at both ends are connected to three metal atoms respectively, forming a cluster of 12 metal cores. The ligands coordinate with the metals through the carbon atoms on the terminal alkynes.

3. The application of the nano-alloy cluster material as described in claim 1 or 2, characterized in that: It was used to prepare a photocatalytic antibacterial agent.

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