SILVER NANOCLUSTER FLUORESCENT NANOTUBE, A PREPARATION METHOD AND ITS APPLICATION IN THE DETECTION OF ARGININE

Abstract

A preparation process of atomically precise nine-nuclear silver nanoclusters (Ag.sub.9-NCs) fluorescent nanotube and its application in the detection of arginine (Arg), the fluorescent nanotube is formed by supramolecular self-assembly of Ag.sub.9-NCs and peptide (DD-5); the fluorescent nanotube prepared by the present invention has good luminescence performance due to its highly ordered structure, the quantum yield is 8.11%, and the fluorescence lifetime is 6.10 μs; after adding Arg, the highly ordered structure is destroyed, resulting in fluorescent quenching; the preparation method of the Ag.sub.9-NCs fluorescent nanotube of this invention is simple, the cost is low; at the same time, the detection method is fast and easy to observe.

Claims

1. A Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube, characterized in that, Ag NCs fluorescent nanotube is obtained by supramolecular self-assembly of Ag.sub.9-NCs under the induction of DD-5; DD-5 is formed by the polymerization of five aspartic acids; the Ag.sub.9-NCs is nine-nuclear Ag NCs with Ag as core and 2-mercaptobenzoic acid (H.sub.2mba) as ligand; the supramolecular self-assembly process is to mix Ag.sub.9-NCs aqueous solution with DD-5, vortex, and let it stand for 8 hours in 20 ° C. incubator to obtain Ag.sub.9-NCs fluorescent nanotube hydrogel.

2. The said silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 1, characterized in that, the Ag.sub.9-NCs fluorescent nanotube has a diameter of 30-50 nm and a length of 5-20 μm.

3. The said silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 1, characterized in that, the fluorescence spectrum of fluorescent nanotube of Ag.sub.9-NCs shows that the excitation wavelength is 400-550 nm, and the emission wavelength is 550-800 nm.

4. The said silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 1, characterized in that, the fluorescence lifetime of Ag.sub.9-NCs fluorescent nanotube is 6.10 μs, and the quantum yield is 8.11%.

5. A preparation method of Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube of claim 1, comprising: AgNO.sub.3 and H.sub.2mba are dispersed in water and carry out ultrasonic treatment, in the ultrasonic treatment process, add NH.sub.3.H.sub.2O to above-mentioned mixture, obtain Ag.sub.9-NCs aqueous solution; the Ag.sub.9-NCs aqueous solution is mixed with DD-5, vortexed, and allowed to stand for 8 hours in 20° C. incubator to obtain Ag.sub.9-NCs fluorescent nanotube hydrogel.

6. The said preparation method of Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 5, characterized in that, the concentration of AgNO.sub.3 dispersed in water is 1 mmol.Math.L.sup.−1, and the concentration of H.sub.2mba dispersed in water is 1 mmol.Math.L.sup.−1; the molar ratio of AgNO.sub.3 and H.sub.2mba is 1:1.

7. The said preparation method of Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 5, characterized in that, the ultrasonic frequency of the ultrasonic treatment is 30-50 kHz, the ultrasonic power is 80 W, and the ultrasonic time is 20-30 minutes.

8. The said preparation method of Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 5, characterized in that, the mass concentration of NH.sub.3H.sub.2O is 25%.

9. The said preparation method of Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 5, characterized in that, the amount of NH.sub.3.H.sub.2O added is until the precipitate completely dissolved.

10. The said preparation method of Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 5, characterized in that, the final molar concentration of DD-5 is 50-80 mmol.Math.L.sup.−1 and the final molar concentration of Ag.sub.9-NCs is 5 mmol.Math.L.sup.−1 when they are well mixed.

11. The said preparation method of Silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube according to claim 5, characterized in that, vortex time is 20-30 s, and stand time is 8 hours.

12. The silver nanocluster (Ag.sub.9-NCs) fluorescent nanotube of claim 1 can be used for the detection of L-Arg.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is molecular structure diagram of substance Ag.sub.9-NCs synthesized in Embodiment 1 of the present invention.

[0038] FIG. 2 are TEM and SEM images of Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 1 of the present invention.

[0039] FIG. 3 is FT-IR of the fluorescent nanotube of Ag.sub.9-NCs prepared in Embodiment 1 of the present invention, wherein: (a) Fluorescent nanotube, (b) DD-5, and (c) Ag.sub.9-NCs.

[0040] FIG. 4 is XRD pattern of the fluorescent nanotube prepared in Embodiment 1 of the present invention, wherein: (a) Fluorescent nanotube, and (b) DD-5.

[0041] FIG. 5 is fluorescence spectrum diagram of Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 1 of the present invention, wherein: (a) Excitation spectrum, (b) Emission spectrum.

[0042] FIG. 6 are TEM and SEM images of Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 2 of the present invention.

[0043] FIG. 7 are TEM and SEM images of Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 3 of the present invention.

[0044] FIG. 8 are TEM and SEM images of Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 4 of the present invention.

[0045] FIG. 9 are optical photographs of the sample under the irradiation of 365 nm ultraviolet lamp after adding different amino acids with the same concentration of 200 mmol.Math.L.sup.−1 to the fluorescent nanotube prepared in Embodiment 1 in Comparative Example 1 of the present invention.

[0046] FIG. 10 are graphs showing the fluorescence properties of the fluorescent nanotube prepared in Embodiment 1 after adding different amino acids with the same concentration of 200 mmol.Math.L.sup.−1 in Comparative Example 1 of the present invention. Among them: the left picture is the fluorescence spectrum obtained by the sample under the excitation of 490 nm, the order from top to bottom is: Blank, Glycine (Gly), L-Asparagine (L-Asn), L-α-Alanine (L-Ala), L-Cysteine (L-Cys), L-Glutamine (L-Gln), L-phenylalanine (L-Phe), L-tyrosine (L-Thr), L-serine (L-Ser), L-valine (L-Val), L-Histidine (L-His) and L-Arginine (L-Arg); The column on the left in the right figure represents the histogram of the ratio of the fluorescence intensity at the wavelength of 630 nm after adding amino acids (I) and before adding amino acids (I.sub.0) to the Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 1, and the column on the right in the right figure represents the histogram of the (I/I.sub.0) ratio at 630 nm after adding other amino acids to the Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 1 of the present invention and continuing to add L-Arg.

[0047] FIG. 11 is graph of the fluorescence properties after adding different concentrations of L-Arg to Embodiment 1 in Comparative Example 2 of the present invention; among them, the left picture is the obtained fluorescence spectrum, the middle picture shows the change of fluorescence intensity at 630 nm, the right figure shows the Stern-Volmer quenching curve of Ag.sub.9-NCs fluorescent nanotube at 630 nm for L-Arg concentration, the fluorescence intensity at 630 nm before adding L-Arg is I, and the fluorescence intensity at 630 nm after adding L-Arg is I.sub.0.

[0048] FIG. 12 is TEM image of fluorescence quenching after adding 200 mmol.Math.L.sup.−1 L-Arg to Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 1 in Comparative Example 2 of the present invention.

[0049] FIG. 13 is FT-IR diagram of fluorescence quenching after adding 200 mmol.Math.L.sup.−1 L-Arg to Ag.sub.9-NCs fluorescent nanotube prepared in Embodiment 1 in Comparative Example 2 of the present invention, wherein: (a) Ag.sub.9-NCs, (b) DD-5, (c) Fluorescent nanotube, (d) Fluorescent nanotube with 200 mmol.Math.L.sup.−1 L-Arg added.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] The invention is further described in combination with Embodiments as follows, but is not limited to that.

[0051] The raw materials used in the embodiment are conventional raw materials available on the market, including: AgNO.sub.3 is purchased from Tianjin Kemeiou Chemical Reagent Co., Ltd., H.sub.2mba is purchased from Sigma-Aldrich, DD-5 is purchased from GL Biochem Ltd. (Shanghai, China), various Amino acids are purchased from Sinopharm Chemical Reagent Co., Ltd, (Shanghai, China), and are used directly without further purification before use.

EXAMPLE 1

[0052] A preparation method of the Ag.sub.9-NCs fluorescent nanotube, including the following steps:

[0053] (1) The Synthesis of Ag.sub.9-NCs

[0054] Accurately weigh AgNO.sub.3 (1 mmol, 170 mg) and H.sub.2mba (1 mmol, 155 mg) are dispersed in 6 mL of water and sonicated in KQ5200DE instrument for 20 min (80 W, 40 kHz). NH.sub.3H.sub.2O (25%, 0.5 mL) is added to the above mixture to obtain a yellow transparent Ag.sub.9-NCs solution.

[0055] (2) Preparation of Ag.sub.9-NCs Fluorescent Nanotube

[0056] Accurately weigh 20.0 mg of DD-5, dissolve it in 355 μL of tertiary water, and vortex for 30 s to fully dissolve, after complete dissolution, pipette 145 μL of Ag.sub.9-NCs aqueous solution, continue to vortex for 30 s to make it evenly mixed, after mixing, the concentration of DD-5 is 70 mmol.Math.L.sup.−1, and then stand in 20° C. incubator for 8 hours.

[0057] The molecular structure diagram of Ag.sub.9-NCs obtained in this Embodiment is shown in FIG. 1. It can be seen from FIG. 1 that Ag.sub.9-NCs is nine-core Ag NCs with Ag as core and H.sub.2mba as ligand.

[0058] The TEM and SEM images of Ag.sub.9-NCs fluorescent nanotube obtained in this Embodiment are shown in FIG. 2. It can be seen from FIG. 2 that Ag.sub.9-NCs fluorescent nanotube is in the state of nanotube, with a width of 30-50 nm and a length of 5-20 μm.

[0059] The FT-IR of fluorescent nanotube of the Ag.sub.9-NCs prepared in this Embodiment is shown in FIG. 3, and it can be seen that the formation of nanotube is mainly driven by hydrogen-bonding.

[0060] The XRD pattern of Ag.sub.9-NCs fluorescent nanotube prepared in this Embodiment is shown in FIG. 4, It can be seen that there is highly ordered structure in the fluorescent nanotube, and there are Ag—Ag, Ag—S and π-π interactions.

[0061] The fluorescence spectrum of Ag.sub.9-NCs fluorescent nanotube prepared in this Embodiment is shown in FIG. 5. It can be seen that the fluorescent nanotube has a wide excitation range with optimal excitation at 490 nm and optimal emission at 630 nm with a large Stokes shift (˜140 nm).

EXAMPLE 2

[0062] As described in Embodiment 1, a preparation method for Ag.sub.9-NCs fluorescent nanotube includes the following steps:

[0063] Accurately weigh 14.8 mg of DD-5, dissolve it in 355 μL of tertiary water, and vortex for 30 s to fully dissolve, after complete dissolution, pipette 145 μL of Ag.sub.9-NCs aqueous solution, continue to vortex for 30 s to make it evenly mixed, after mixing, the concentration of DD-5 is 50 mmol.Math.L.sup.−1,and then stand in 20° C. incubator for 8 hours.

[0064] The molecular structure diagram of Ag.sub.9-NCs obtained in this Embodiment is shown in FIG. 1. It can be seen from FIG. 1 that Ag.sub.9-NCs is nine-core Ag NCs.

[0065] The TEM and SEM of Ag.sub.9-NCs fluorescent nanotube obtained in this Embodiment are shown in FIG. 6, the Ag.sub.9-NCs fluorescent nanotube is in the state of nanotube, with a width of 30-50 nm and a length of 5-20 μm.

EXAMPLE 3

[0066] As described in Embodiment 1, a preparation method for Ag.sub.9-NCs fluorescent nanotube includes the following steps:

[0067] Accurately weigh 17.8 mg of DD-5, dissolve it in 355 μL of tertiary water, and vortex for 30 s to fully dissolve, after complete dissolution, pipette 145 μL of Ag.sub.9-NCs aqueous solution, continue to vortex for 30 s to make it evenly mixed, after mixing, the concentration of DD-5 is 60 mmol.Math.L.sup.−1, and then stand in 20° C. incubator for 8 hours.

[0068] The molecular structure diagram of Ag.sub.9-NCs obtained in this Embodiment is shown in FIG. 1. It can be seen from FIG. 1 that Ag.sub.9-NCs is nine-core Ag NCs.

[0069] The TEM and SEM of Ag.sub.9-NCs fluorescent nanotube obtained in this Embodiment are shown in FIG. 7, the Ag.sub.9-NCs fluorescent nanotube is in the state of nanotube, with a width of 30-50 nm and a length of 5-20 μm.

EXAMPLE 4

[0070] As described in Embodiment 1, a preparation method for Ag.sub.9-NCs fluorescent nanotube includes the following steps:

[0071] Accurately weigh 23.7 mg of DD-5, dissolve it in 355 μL of tertiary water, and vortex for 30 s to fully dissolve, after complete dissolution, pipette 145 μL of Ag.sub.9-NCs aqueous solution, continue to vortex for 30 s to make it evenly mixed, after mixing, the concentration of DD-5 is 80 mmol.Math.L.sup.−1, and then stand in 20° C. incubator for 8 hours.

[0072] The molecular structure diagram of Ag.sub.9-NCs obtained in this Embodiment is shown in FIG. 1. It can be seen from FIG. 1 that Ag.sub.9-NCs is nine-core Ag NCs.

[0073] The TEM and SEM of Ag.sub.9-NCs fluorescent nanotube obtained in this Embodiment are shown in FIG. 8, fluorescent nanotube is in the state of nanotube, with a width of 30-50 nm and a length of 5-20 μm.

TEST EXAMPLE 1

[0074] Pipette 100 μL of amino acid (L-Arg, L-Ala, L-His, L-Cys, L-Phe, L-Gln, L-Ser, L-Thr, -Asn, L-Val and Gly) aqueous solution with a concentration of 200 mmol.Math.L.sup.−1 into 100 μL of Ag.sub.9-NCs fluorescent hydrogel prepared in Embodiment 1, vortex for 20 s to make it evenly mixed, and let stand for 8 hours, then observe the sample under UV lamp with a wavelength of 365 nm, as shown in FIG. 9.

[0075] The Ag.sub.9-NCs fluorescent nanotube and the samples after adding different kinds of amino acids are transferred to triangular quartz cuvettes, respectively, and the emission spectra of the samples are measured using fluorescence spectrophotometer, as shown in FIG. 10 (left). The interference detection of L-Arg in Ag.sub.9-NCs fluorescent nanotube is shown in FIG. 10 (right).

[0076] After the introduction of Ag.sub.9-NCs in DD-5, due to intermolecular hydrogen-bonding, π-π interaction and argentophilic interactions, highly ordered aggregates are formed, which induces the AIE effect of Ag.sub.9-NCs and makes it emit fluorescence. As shown in FIG. 9, 10 (left) and (right), after adding different kinds of amino acids, it can be found that L-Arg can completely quench the fluorescence, and the addition of other amino acids has little effect on the fluorescence intensity. It shows that the fluorescent nanotube prepared by the present invention has high selectivity in the detection of L-Arg. This phenomenon can be observed using both portable UV lamp and fluorescence spectrum, and the inspection results are easy to observe and measure.

TEST EXAMPLE 2

[0077] Pipette 100 μL of L-Arg aqueous solutions of different concentrations into 100 μL of the fluorescent hydrogel of Ag.sub.9-NCs prepared in Embodiment 1, vortex for 20 s to make them evenly mixed, and let stand for 8 hours. The samples containing different concentrations of L-Arg are transferred into triangular quartz cuvettes, and emission spectra of the samples are measured using fluorescence spectrophotometer, and the results are shown in FIG. 11 (left). After adding different concentrations of L-Arg to Ag.sub.9-NCs fluorescent nanotube, the change of fluorescence intensity at 630 nm is shown in FIG. 11 (middle). The Stern-Volmer quenching curve of Ag.sub.9-NCs fluorescent nanotube at 630 nm for L-Arg concentration is shown in FIG. 11 (right).

[0078] The calculated detection limit is 330 μmol.Math.L.sup.−1, which indicates that Ag.sub.9-NCs fluorescent nanotube prepared by the present invention has sensitivity in the detection of L-Arg.

[0079] After fluorescent nanotube prepared in Embodiment 1 are added with L-Arg and final L-Arg concentration is 100 mmol.Math.L.sup.−1, the obtained non-fluorescent solution is characterized by TEM, as shown in FIG. 12. Non-fluorescent solution is lyophilized into powder for FT-IR test, the results are shown in FIG. 13.

[0080] As shown in FIG. 12, after the addition of L-Arg, the highly ordered nanotube disappeared, and more particles with ultrafine nanowires appeared, indicating that the addition of L-Arg destroyed the nanotube structure. As shown in FIG. 13, after the addition of L-Arg, the stretching vibration peak belonging to the carbonyl group in Ag.sub.9-NCs reappeared, and the peak of the DD-5 amide I band also reappeared, indicating that the addition of L-Arg destroyed the intermolecular hydrogen-bonding, reducing the radiative relaxation of ligand, then fluorescence disappeared.