Preparation method of chiral amino acid particles for rapid recognition by colorimetric method

Abstract

The invention discloses a preparation method of chiral amino acid particles for rapid recognition by a colorimetric method, which comprises the following steps: by taking L-tryptophan and hexadecyl trimethyl ammonium bromide as raw materials, preparing flower-shaped chiral amino acid particles (L-TNP) at room temperature through chiral induction and a template stabilization mechanism. The method is simple and mild in reaction condition, the prepared L-TNP can be used as a colorimetric probe, excellent enantioselective colorimetric distinguishing of histidine, glutamic acid, phenylalanine, tryptophan and enantiomers thereof is realized under the assistance of Cu < 2 + >, and the method has the advantages of low cost, easiness in material synthesis, simplicity in operation and the like, and is suitable for industrial production. The method has a certain application prospect in the aspects of chiral distinguishing, purity identification and the like of chiral amino acids.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation, and in particular relates to a method for preparing chiral amino acid particles for rapid colorimetric identification. Background Art

[0002] Chirality is an important concept in molecular chemistry, which refers to the non-overlapping nature between a molecule and its mirror image. Chirality is ubiquitous in nature and plays a vital role in the structure and function of organisms. Chiral molecules, especially enantiomers of amino acids, often exhibit distinct biological activities. Currently, the active ingredients of many drugs are chiral amino acids, and the differences in the biological activities of their enantiomers make chiral analysis particularly important in drug development and biomedicine.

[0003] Traditional chiral separation and identification methods mainly include chromatography and spectroscopy, such as high performance liquid chromatography, gas chromatography and capillary electrophoresis. Although these methods have high sensitivity and resolution in chiral analysis, they usually require expensive instruments and complex operating procedures. In addition, the analysis cycle is long, which limits its practicality in rapid detection and field applications. Therefore, it is particularly important to develop a low-cost, fast and simple method for chiral amino acid identification.

[0004] As an intuitive, simple and economical chiral recognition technology, colorimetry has attracted widespread attention because it can recognize chiral molecules through visual color changes. Nanoparticles (such as silver nanoparticles and gold nanoparticles) are used as colorimetric probes to effectively respond to different chiral molecules. However, the existing nanoparticle-based colorimetric chiral recognition technology still has problems such as complex synthesis process and high material cost. Summary of the invention

[0005] The present invention provides a method for preparing flower-shaped chiral amino acid particles based on L-tryptophan and hexadecyltrimethylammonium bromide as raw materials, which utilizes the synergistic effect of L-tryptophan and hexadecyltrimethylammonium bromide surfactants at room temperature to prepare flower-shaped chiral amino acid particles (L-TNP) under simple and mild reaction conditions. The particles are used as colorimetric probes in Cu 2+ With the assistance of , the enantiomers of histidine, glutamic acid, phenylalanine and tryptophan can be effectively distinguished, showing excellent enantioselective colorimetric differentiation ability. This method has the advantages of low cost, simple synthesis and convenient operation, and has broad application prospects in the fields of chiral differentiation and purity identification of chiral amino acids.

[0006] To achieve the above object, the present invention adopts the following technical solution: A chiral amino acid particle for rapid colorimetric identification, the preparation method of which is to add L-tryptophan and hexadecyltrimethylammonium bromide into water, and obtain flower-shaped chiral amino acid particles (L-TNP) by stirring.

[0007] Furthermore, the molar ratio of L-tryptophan to hexadecyltrimethylammonium bromide is 100:1.

[0008] Furthermore, the stirring temperature is room temperature, the time is 3 min, and the rotation speed is 600 rpm.

[0009] The isoelectric point of tryptophan is 5.89, and it is negatively charged in aqueous solution with a pH close to 7. It can generate electrostatic interaction with the quaternary ammonium cation of hexadecyltrimethylammonium bromide. The indole ring of tryptophan adsorbs with the long alkyl chain of hexadecyltrimethylammonium bromide through hydrophobic interaction. Therefore, by utilizing the synergistic effect of L-tryptophan and hexadecyltrimethylammonium bromide surfactant, combined with mechanisms such as chiral induction, surface adsorption and template stabilization, the growth of nanoparticles along a specific chiral direction can be regulated and induced, effectively promoting the formation of chiral flower-like nanoparticles.

[0010] The obtained chiral amino acid particles can be used for rapid colorimetric identification of chiral amino acids, specifically in Cu 2+ With the assistance of , the chiral amino acid particles are used to realize rapid colorimetric recognition of chiral amino acids.

[0011] Furthermore, the chiral amino acids include histidine, glutamic acid, phenylalanine, tryptophan and their enantiomers.

[0012] Furthermore, the Cu 2+ Can be derived from CuCl2.

[0013] The mechanism of chiral amino acid particles achieving chiral recognition may involve multiple effects such as electrostatic interaction, hydrophobic interaction, coordination effect, and steric effect.

[0014] The significant advantages of the present invention are: The present invention provides a method for preparing chiral amino acid particles that can be used for rapid colorimetric identification, wherein L-tryptophan and hexadecyltrimethylammonium bromide are used as raw materials, and flower-shaped chiral amino acid particles (L-TNP) are prepared at room temperature through chiral induction and template stabilization mechanisms. The method has simple and mild reaction conditions, and the obtained L-TNP can be used as a colorimetric probe in Cu 2+ With the assistance of , it exhibits excellent enantioselective colorimetric distinction of histidine, glutamic acid, phenylalanine, tryptophan and their enantiomers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1This is a diagram showing the effect of products prepared with different ratios of L-tryptophan and hexadecyltrimethylammonium bromide.

[0016] Figure 2 The scanning electron micrographs of amino acid particles prepared by L-tryptophan and hexadecyltrimethylammonium bromide in different ratios, wherein A is 100:1 and B is 100:2.

[0017] Figure 3 This is the particle size distribution diagram of L-TNP prepared with a molar ratio of L-tryptophan and hexadecyltrimethylammonium bromide of 100:1.

[0018] Figure 4 This is the circular dichroism spectrum of L-TNP prepared with a molar ratio of L-tryptophan and hexadecyltrimethylammonium bromide of 100:1.

[0019] Figure 5 The figure (a) and its infrared spectrum (b) of the effect of L-TNP recognizing L-histidine and D-histidine in Example 2.

[0020] Figure 6 The effect diagram (a) and infrared spectrum diagram (b) of L-TNP recognizing L-glutamic acid and D-glutamic acid in Example 2 are shown.

[0021] Figure 7 The effect diagram (a) and infrared spectrum diagram (b) of L-TNP recognizing L-phenylalanine and D-phenylalanine in Example 2.

[0022] Figure 8 The effect diagram (a) and infrared spectrum diagram (b) of L-TNP recognizing L-tryptophan and D-tryptophan in Example 2 are shown.

[0023] Fig. 9 The UV-visible spectra of different materials obtained in Example 3 are shown in FIG.

[0024] Fig.10 is the L-TNP+Cu obtained in Example 3 2+ High-resolution mass spectrum and local magnification (a) and possible structural formula of the product (b). DETAILED DESCRIPTION

[0025] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0026] Example 1 Preparation of Flower-shaped Chiral Amino Acid Particles 10 mL of water was measured and placed in a beaker, and then 204.23 mg of L-tryptophan and 3.64 mg of hexadecyltrimethylammonium bromide (molar ratio 100:1) were added, and stirred at room temperature at 600 rpm for 3 min to obtain a suspension containing chiral amino acid particles.

[0027] In addition, the molar ratios of L-tryptophan and hexadecyltrimethylammonium bromide were adjusted to 200:1 and 100:2 to prepare suspensions containing corresponding amino acid particles.

[0028] like Figure 1 As shown, when the molar ratio of L-tryptophan to hexadecyltrimethylammonium bromide is 100:1 and 100:2, brown-yellow and light-yellow suspensions are obtained, respectively, and the liquids are relatively clear and transparent; when the molar ratio of L-tryptophan to hexadecyltrimethylammonium bromide reaches 200:1, more white precipitates appear at the bottom of the light-yellow liquid, which may be due to excessive saturation of L-tryptophan, resulting in insufficient dissolution.

[0029] Further investigation of the surface morphology of the amino acid particles obtained when the molar ratio was 100:1 and 100:2 showed that Figure 2 .Depend on Figure 2 The results showed that when the molar ratio of L-tryptophan and hexadecyltrimethylammonium bromide was 100:1, the obtained nanoparticles had a typical, complete flower-like structure with a diameter of about 350 nm; while when the molar ratio of the raw materials was 100:2, the material appeared as partial flower-like fragments with poor uniformity and a diameter of about 180 nm.

[0030] The particle size analysis of amino acid particles (L-TNP) prepared with a molar ratio of 100:1 was performed, and the results are as follows Figure 3 As shown. Figure 3 It can be seen that the particle size range of the chiral particles is 343±30 nm (n=3), which is basically consistent with the scanning electron microscopy results.

[0031] In addition, the circular dichroism spectrum of the L-TNP was also investigated. Figure 4 shown. Figure 4 This once again verified that the material has asymmetric molecular and chiral selective properties.

[0032] Example 2 Application of flower-shaped chiral amino acid particles (L-TNP) (1) Weigh 0.50 mL of the suspension containing L-TNP (molar ratio 100:1) prepared in Example 1 and add it to centrifuge tubes containing 0.50 mL of 1 mg / mL L-histidine and D-histidine, vortex for 30 s, and then add 0.50 mL of 13.44 mg / mL CuCl2. The results are shown in Table 1. Figure 5 .

[0033] Depend on Figure 5 It can be seen that adding Cu 2+ After that, the L-histidine solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to blue, while the D-histidine solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to light green; combined with the infrared spectrum, it can be seen that L-TNP formed different complexes with L-histidine and D-histidine through the carboxyl and amino groups on the amino acids, respectively, which indicates that L-TNP has good colorimetric discrimination performance for L-histidine and D-histidine, respectively.

[0034] (2) Weigh 0.50 mL of the suspension containing L-TNP (molar ratio 100:1) prepared in Example 1 and add it to centrifuge tubes containing 0.50 mL of L-glutamic acid and D-glutamic acid at a concentration of 1 mg / mL, vortex for 30 s, and then add 0.50 mL of 13.44 mg / mL CuCl2. The results are shown in Table 1. Figure 6 .

[0035] Depend on Figure 6 It can be seen that adding Cu 2+ After that, the L-glutamic acid solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to light blue, while the D-glutamic acid solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to light green; combined with the infrared spectrum, it can be seen that L-TNP formed different complexes with L-glutamic acid and D-glutamic acid through the carboxyl and amino groups on the amino acids, respectively, which indicates that L-TNP has good colorimetric discrimination performance for L-glutamic acid and D-glutamic acid, respectively.

[0036] (3) Weigh 0.50 mL of the suspension containing L-TNP (molar ratio 100:1) prepared in Example 1 and add it to centrifuge tubes containing 0.50 mL of L-phenylalanine and D-phenylalanine at a concentration of 1 mg / mL, vortex for 30 s, and then add 0.50 mL of 13.44 mg / mL CuCl2. The results are shown in Table 1. Figure 7 .

[0037] Depend on Figure 7 It can be seen that adding Cu 2+ After that, the L-phenylalanine solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to light green, while the D-phenylalanine solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to dark green precipitate; combined with the infrared spectrum, it can be seen that L-TNP and L-phenylalanine and D-phenylalanine formed different complexes through the carboxyl and amino groups on the amino acids, which indicates that L-TNP has good colorimetric discrimination performance for L-phenylalanine and D-phenylalanine, respectively.

[0038] (4) Weigh 0.50 mL of the suspension containing L-TNP (molar ratio 100:1) prepared in Example 1 and add it to centrifuge tubes containing 0.50 mL of L-tryptophan and D-tryptophan at a concentration of 1 mg / mL, vortex for 30 s, and then add 0.50 mL of 13.44 mg / mL CuCl2. The results are shown in Table 1. Figure 8 .

[0039] Depend on Figure 8 It can be seen that adding Cu 2+ After that, the L-tryptophan solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to a dark green precipitate, while the D-tryptophan solution containing L-TNP obviously changed from the brown-yellow color of L-TNP to a blue precipitate; combined with the infrared spectrum, it can be seen that L-TNP respectively bonded with L-tryptophan and D-tryptophan through the carboxyl and amino groups on the amino acids to form different complexes, which indicates that L-TNP has a good colorimetric distinction performance for L-tryptophan and D-tryptophan.

[0040] Example 3 The experiment takes the tryptophan enantiomer in Example 2 as an example to explore the possible mechanism of the chiral amino acid particle (L-TNP) to quickly identify several types of chiral amino acids. Specifically, the UV-visible spectra of various materials in Example 2 were scanned in the range of 200-800 nm. The results are shown in Fig. 9 .

[0041] Depend on Fig. 9 The results showed that the UV spectra of pure L-tryptophan and D-tryptophan (30 μg / mL) were basically overlapping, and both had two absorption peaks at 220 nm and 279 nm, of which 279 nm was attributed to the conjugated system of the indole ring. 2+ +L-tryptophan and L-TNP+Cu 2+ There is no significant difference in the absorption wavelength of the supernatant of +D-tryptophan and the spectrum of pure L-tryptophan, and no obvious peak is seen in the visible light range, indicating that the main contribution to the ultraviolet absorption of the reaction system is still from L-tryptophan, but the product formed after the reaction is conducive to the increase of the absorbance intensity.

[0042] The suspension containing L-TNP (molar ratio 100:1) obtained in Example 1 was further added with CuCl2 and centrifuged at 10000 rpm for 5 min. The supernatant was taken and identified by high-resolution mass spectrometry. The results are shown in FIG. Fig.10 .

[0043] Depend on Fig.10 The results show that in the electrospray ionization positive ion scanning mode, L-TNP+Cu 2+The characteristic ion peaks of the two raw materials can be obtained in the mass spectrum (a), among which L-tryptophan (C 11 H 12 N2O2, accurate molecular weight is 204.0899) and a strong [M+H] + Peak (m / z measured value 205.0981, mass deviation 4.51ppm), hexadecyltrimethylammonium bromide (C 19 H 42 NBr, accurate molecular weight is 363.2501) Since bromide ions are easily lost in solution, C 19 H 42 N + (Theoretical value 284.3312, measured value 284.3326, mass deviation 4.52ppm). At the same time, several weak characteristic peaks were measured. After accurate mass number fitting and isotope peak characteristic inference, they were identified as a series of compounds (b) formed by copper-tryptophan complexation, namely C 22 H 24 N4O4Cu (characteristic m / z is 472.1169), C 22 H 27 N4O2Cu2 (characteristic m / z is 506.0802), C 22 H 27 N4O2Cu3 (characteristic m / z is 602.9752). The formation of the above complex is because the tryptophan molecule contains active sites such as benzene ring, indole ring, amino group, and carboxyl group, which can provide multiple coordination sites for copper ions.

[0044] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing chiral amino acid particles for rapid colorimetric identification, characterized in that: L-tryptophan and hexadecyltrimethylammonium bromide are added into water and stirred to obtain flower-shaped chiral amino acid particles.

2. The method for preparing chiral amino acid particles according to claim 1, characterized in that: The molar ratio of L-tryptophan to hexadecyltrimethylammonium bromide used was 100:

1.

3. The method for preparing chiral amino acid particles according to claim 1, characterized in that: The stirring temperature is room temperature, the time is 3 min, and the rotation speed is 600 rpm.

4. A chiral amino acid particle prepared by the method of claim 1.

5. Use of the chiral amino acid particle as claimed in claim 4 in rapid identification of chiral amino acids by colorimetry.

6. Use according to claim 5, characterized in that Specifically, in Cu 2+ With the assistance of , the chiral amino acid particles are used to perform rapid colorimetric identification of chiral amino acids.

7. The use according to claim 5, characterized in that The chiral amino acids are histidine, glutamic acid, phenylalanine, tryptophan and their enantiomers.

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