A preparation method of chiral amino acid particles for rapid identification by colorimetry

Abstract

The application discloses a preparation method of chiral amino acid particles for colorimetric rapid identification, which takes L-tryptophan and cetyltrimethylammonium bromide as raw materials, and prepares a flower-shaped chiral amino acid particle (L-TNP) at room temperature through chiral induction and template stabilization mechanism. 2+ The prepared L-TNP can be used as a colorimetric probe, and can realize excellent enantioselective colorimetric distinction of histidine, glutamic acid, phenylalanine, tryptophan and enantiomers thereof under the assistance of Cu, and has the advantages of low cost, easy material synthesis and simple operation, and has certain application prospect in chiral distinction and purity identification of chiral amino acids.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material preparation, and particularly relates to a preparation method of chiral amino acid particles for rapid identification by colorimetry. BACKGROUND

[0002] Chirality is an important concept in molecular chemistry, referring to the non-coincidence between a molecule and its mirror image. Chirality is ubiquitous in nature and plays a crucial role in the structure and function of living organisms. Chiral molecules, especially enantiomers of amino acids, often exhibit distinct biological activities. Currently, many pharmaceutical active ingredients are chiral amino acids, and the biological activity difference between their enantiomers makes chiral analysis particularly important in drug development and biomedical fields.

[0003] Traditional chiral separation and identification methods mainly include chromatography and spectroscopy, such as high-performance liquid chromatography, gas chromatography, and capillary electrophoresis, etc. Although these methods have high sensitivity and resolution in chiral analysis, they usually require expensive equipment and complex operation procedures. In addition, the analysis period is relatively long, which limits their practicality in rapid detection and on-site application. Therefore, it is particularly important to develop a low-cost, rapid, and simple chiral amino acid identification method.

[0004] Colorimetry, as an intuitive, simple, and economical chiral identification technology, has attracted widespread attention due to its ability to identify chiral molecules through visual color changes. Using nanoparticles (such as silver nanoparticles, gold nanoparticles) as colorimetric probes can effectively respond to different chiral molecules. However, existing colorimetric chiral recognition techniques based on nanoparticles still have problems such as complex synthesis process and high material cost. SUMMARY

[0005] The application provides a preparation method of flower-shaped chiral amino acid particles based on L-tryptophan and cetyltrimethylammonium bromide as raw materials. The method utilizes the synergistic effect of L-tryptophan and cetyltrimethylammonium bromide surfactant at room temperature to prepare flower-shaped chiral amino acid particles (L-TNP) under simple and mild reaction conditions. Using the particles as colorimetric probes, they can effectively distinguish the enantiomers of glycine, glutamic acid, phenylalanine, and tryptophan under the assistance of Cu 2+ , showing excellent enantioselective colorimetric discrimination ability. This method has the advantages of low cost, simple synthesis, and easy operation, and has wide application prospects in the fields of chiral discrimination and purity identification of chiral amino acids.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0007] A kind of chiral amino acid particle for colorimetric rapid identification, its preparation method is to add L-tryptophan and hexadecyl trimethyl ammonium bromide in water, and flower-shaped chiral amino acid particle (L-TNP) is prepared by stirring.

[0008] Further, the molar ratio of L-tryptophan and hexadecyl trimethyl ammonium bromide used is 100:1.

[0009] Further, the temperature of the stirring is room temperature, the time is 3 min, and the rotation speed is 600 rpm.

[0010] The isoelectric point pI of tryptophan is 5.89, and it presents a negative charge in an aqueous solution with a pH close to 7, which can generate electrostatic interaction with the quaternary ammonium positive ion of hexadecyl trimethyl ammonium bromide. The indole ring of tryptophan is adsorbed by the long alkyl chain of hexadecyl trimethyl ammonium bromide through hydrophobic interaction. Therefore, by using the synergistic effect of L-tryptophan and hexadecyl trimethyl ammonium bromide surfactant, combined with mechanisms such as chiral induction, surface adsorption and template stabilization, the growth of nanoparticles in a specific chiral direction can be regulated and induced, effectively promoting the formation of chiral flower-shaped nanoparticles.

[0011] The obtained chiral amino acid particles can be used for colorimetric rapid identification of chiral amino acids. Specifically, under the assistance of Cu 2+ , the chiral amino acid particles are used to realize rapid colorimetric identification of chiral amino acids.

[0012] Further, the chiral amino acid includes histidine, glutamic acid, phenylalanine, tryptophan and its enantiomers.

[0013] Further, the Cu 2+ may be derived from CuCl2.

[0014] The mechanism of chiral recognition of the chiral amino acid particles may involve multiple actions such as electrostatic interaction, hydrophobic interaction, coordination, and steric effect.

[0015] The significant advantages of the present application are:

[0016] The present application provides a preparation method of chiral amino acid particles applicable to colorimetric rapid identification. The method uses L-tryptophan and hexadecyl trimethyl ammonium bromide 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 reaction conditions of the method are simple and mild. The obtained L-TNP as a colorimetric probe can exhibit excellent enantioselective colorimetric discrimination for histidine, glutamic acid, phenylalanine, tryptophan and their enantiomers under the assistance of Cu 2+ . BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1The effect picture of the product prepared by L-tryptophan and cetyltrimethylammonium bromide in different proportions.

[0018] Figure 2 The scanning electron microscope picture of the amino acid particles prepared by L-tryptophan and cetyltrimethylammonium bromide in different proportions, wherein A is 100:1 and B is 100:2.

[0019] Figure 3 The particle size distribution picture of L-TNP prepared by L-tryptophan and cetyltrimethylammonium bromide in a molar ratio of 100:1.

[0020] Figure 4 The circular dichroism spectrum picture of L-TNP prepared by L-tryptophan and cetyltrimethylammonium bromide in a molar ratio of 100:1.

[0021] Figure 5 The effect picture (a) and infrared spectrum picture (b) of L-TNP recognizing L-histidine and D-histidine in Example 2.

[0022] Figure 6 The effect picture (a) and infrared spectrum picture (b) of L-TNP recognizing L-glutamic acid and D-glutamic acid in Example 2.

[0023] Figure 7 The effect picture (a) and infrared spectrum picture (b) of L-TNP recognizing L-phenylalanine and D-phenylalanine in Example 2.

[0024] Figure 8 The effect picture (a) and infrared spectrum picture (b) of L-TNP recognizing L-tryptophan and D-tryptophan in Example 2.

[0025] Figure 9 The ultraviolet-visible spectrum picture of different materials obtained in Example 3.

[0026] Figure 10 The high resolution mass spectrum picture and local magnification picture (a) and possible structure formula (b) of L-TNP+Cu 2+ obtained in Example 3. DETAILED DESCRIPTION

[0027] In order to make the content of the present application more convenient to understand, the technical solutions of the present application are further described below in combination with specific embodiments, but the present application is not limited to this.

[0028] Preparation of chiral amino acid particles in the form of flowers in Example 1

[0029] Take 10 mL water in a beaker, then add 204.23 mg L-tryptophan and 3.64 mg cetyltrimethylammonium bromide (molar ratio 100:1), stir at 600 rpm for 3 min at room temperature, to prepare a suspension containing chiral amino acid particles.

[0030] Adjust the molar ratio of L-tryptophan and cetyltrimethylammonium bromide to 200:1 and 100:2 respectively to prepare suspensions containing corresponding amino acid particles.

[0031] As shown in Figure 1 , when the molar ratio of L-tryptophan and cetyltrimethylammonium bromide is 100:1 and 100:2, respectively, brownish yellow and light yellow suspensions are prepared, and the liquid phase is relatively clear and transparent; when the molar ratio of L-tryptophan and cetyltrimethylammonium bromide reaches 200:1, more white precipitate appears at the bottom of the light yellow liquid, which may be due to the excessive amount of L-tryptophan, which is not fully dissolved due to saturation.

[0032] Further investigate the surface morphology of the amino acid particles prepared at a molar ratio of 100:1 and 100:2, and the results are shown in Figure 2 . The Figure 2 results show that when the molar ratio of L-tryptophan and cetyltrimethylammonium bromide is 100:1, the obtained nanoparticles have a typical, complete flower-like structure with a diameter of about 350 nm; when the molar ratio of raw materials is 100:2, the material presents as partial flower-like fragments with poor uniformity, and the diameter is about 180 nm.

[0033] The particle size analysis of the amino acid particles prepared at a molar ratio of 100:1 (L-TNP) is shown in Figure 3 . As can be seen from Figure 3 , the particle size of the chiral particles is 343±30 nm (n=3), which is basically consistent with the scanning electron microscope results.

[0034] The circular dichroism spectrum of the L-TNP is also investigated, and the results are shown in Figure 4 . Figure 4 Again, it is verified that the material has asymmetric molecules and chiral selection properties.

[0035] Example 2 Application of flower-like chiral amino acid particles (L-TNP)

[0036] (1) Take 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-histidine and D-histidine with a concentration of 1 mg / mL, respectively, vortex for 30 s, then add 0.50 mL of 13.44 mg / mL CuCl2, and the results are shown in Figure 5.

[0037] By Figure 5 It can be seen that after adding Cu 2+ , the L-histidine solution containing L-TNP changed obviously from brownish yellow to blue, and the D-histidine solution containing L-TNP changed obviously from brownish yellow to light green; combined with the infrared spectrum, it can be seen that L-TNP bonded with L-histidine and D-histidine through the carboxyl and amino groups on the amino acids to form different complexes, which shows that L-TNP has good colorimetric distinguishing performance for L-histidine and D-histidine, respectively.

[0038] (2) 0.50 mL of the suspension liquid containing L-TNP (molar ratio 100:1) prepared in Example 1 was weighed and added into centrifuge tubes containing 0.50 mL of L-glutamic acid and D-glutamic acid with a concentration of 1 mg / mL, respectively, and vortexed for 30 s, and then 0.50 mL of 13.44 mg / mL CuCl2 was added, respectively, and the results are shown in Table 2. Figure 6 .

[0039] By Figure 6 It can be seen that after adding Cu 2+ , the L-histidine solution containing L-TNP changed obviously from brownish yellow to blue, and the D-histidine solution containing L-TNP changed obviously from brownish yellow to light green; combined with the infrared spectrum, it can be seen that L-TNP bonded with L-histidine and D-histidine through the carboxyl and amino groups on the amino acids to form different complexes, which shows that L-TNP has good colorimetric distinguishing performance for L-histidine and D-histidine, respectively.

[0040] (3) 0.50 mL of the suspension liquid containing L-TNP (molar ratio 100:1) prepared in Example 1 was weighed and added into centrifuge tubes containing 0.50 mL of L-phenylalanine and D-phenylalanine with a concentration of 1 mg / mL, respectively, and vortexed for 30 s, and then 0.50 mL of 13.44 mg / mL CuCl2 was added, respectively, and the results are shown in Table 3. Figure 7 .

[0041] By Figure 7 It can be seen that after adding Cu 2+ , the L-histidine solution containing L-TNP changed obviously from brownish yellow to blue, and the D-histidine solution containing L-TNP changed obviously from brownish yellow to light green; combined with the infrared spectrum, it can be seen that L-TNP bonded with L-histidine and D-histidine through the carboxyl and amino groups on the amino acids to form different complexes, which shows that L-TNP has good colorimetric distinguishing performance for L-histidine and D-histidine, respectively.

[0042] (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, each with a concentration of 1 mg / mL. Vortex for 30 s, and then add 0.50 mL of CuCl2 at a concentration of 13.44 mg / mL. The results are shown in the figure. Figure 8 .

[0043] Depend on Figure 8 It can be seen that adding Cu 2+ Subsequently, the L-tryptophan solution containing L-TNP changed significantly from the brownish-yellow color of L-TNP to a dark green precipitate, while the D-tryptophan solution containing L-TNP changed significantly from the brownish-yellow color of L-TNP to a blue precipitate. Combined with the infrared spectrum, it can be seen that L-TNP forms different complexes with L-tryptophan and D-tryptophan through carboxyl and amino bonds on the amino acids, respectively. This indicates that L-TNP has a good colorimetric distinguishing performance for L-tryptophan and D-tryptophan.

[0044] Example 3

[0045] Using the tryptophan enantiomer in Example 2 as an example, this experiment explores the possible mechanism by which the chiral amino acid particle (L-TNP) rapidly recognizes several classes of chiral amino acids. Specifically, the UV-Vis spectra of various materials in Example 2 were scanned in the 200-800 nm range, and the results are shown in [Figure 1]. Figure 9 .

[0046] Depend on Figure 9 The results showed that the UV spectra of L-tryptophan and D-tryptophan (30 μg / mL) largely overlapped, with both exhibiting two absorption peaks at 220 nm and 279 nm, the latter attributed to the conjugated system of the indole ring. However, the same concentrations of L-TNP suspension and L-TNP+Cu... 2+ +L-tryptophan and L-TNP+Cu 2+ The absorption wavelength of the supernatant of +D-tryptophan was not significantly different from that of L-tryptophan alone, and no obvious peaks were observed in the visible light range. This indicates that L-tryptophan still contributes the main contribution to the ultraviolet absorption of the reaction system, but the product formed after the reaction is beneficial to the increase of absorbance intensity.

[0047] Further, the suspension containing L-TNP (molar ratio 100:1) obtained in Example 1 was added to CuCl2, centrifuged at 10000 rpm for 5 min, and the supernatant was collected and identified by high-resolution mass spectrometry. The results are shown in [Figure 1]. Figure 10 .

[0048] Depend on Figure 10The results show that in the positive ion scan mode of electrospray ionization, the mass spectrum of L-TNP+Cu 2+ (a) can obtain characteristic ion peaks of two raw materials, in which L-tryptophan (C 11 H 12 N2O2, the accurate molecular weight is 204.0899) measures a strong [M+H] + peak (m / z measured value 205.0981, mass deviation 4.51ppm), and cetyltrimethylammonium bromide (C 19 H 42 NBr, the accurate molecular weight is 363.2501) is easy to lose bromide ion in solution, so C 19 H 42 N + (theoretical value 284.3312, measured value 284.3326, mass deviation 4.52ppm) is measured. At the same time, several weak characteristic peaks are also measured, which are inferred to be a series of compounds formed by copper-tryptophan complex (b) by accurate mass fitting and isotope peak characteristics, respectively C 22 H 24 N4O4Cu (the characteristic m / z is 472.1169), C 22 H 27 N4O2Cu2 (the characteristic m / z is 506.0802), C 22 H 27 N4O2Cu3 (the characteristic m / z is 602.9752). The formation of the above complexes is because the tryptophan molecule contains benzene ring, indole ring, amino, carboxyl and other active sites, which can provide multiple coordination sites for copper ions.

[0049] The above only describes the preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be covered by the present application.

Claims

1. The use of chiral amino acid particles in the rapid identification of chiral amino acids by colorimetry, characterized in that, The preparation of the chiral amino acid particles is stirring L-tryptophan and cetyltrimethylammonium bromide in water to obtain flower-shaped chiral amino acid particles; The molar ratio of L-tryptophan and cetyltrimethylammonium bromide is 100:1; The stirring temperature is room temperature, the stirring time is 3 min, and the stirring speed is 600 rpm; Its application is particularly in Cu 2+ The application relates to a method for rapid colorimetric recognition of chiral amino acids by using chiral amino acid particles under the assistance of Cu 2. Use according to claim 1, characterized in that, The chiral amino acid is histidine, glutamic acid, phenylalanine, tryptophan and its enantiomers.

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