Fluorescent probe for detecting viscosity of mask essence as well as preparation method and application of fluorescent probe

Abstract

The invention relates to the field of viscosity detection, and provides a fluorescent probe for detecting the viscosity of mask essence as well as a preparation method and application of the fluorescent probe. 4, 4 '-(iminomethylene) bis (N, N-dimethylaniline) which is slightly soluble in water reacts with acid to form auramine hydrochloride, the water solubility of the auramine hydrochloride fluorescent probe is greatly enhanced, the probe in a water phase is converted into heat (non-radiation decay) due to twisted intramolecular charge transfer and excited state energy caused by benzene ring rotation, and fluorescence quenching is shown; when the viscosity of the solvent is increased, rotation of the benzene ring is blocked, excited state energy cannot be converted into heat and is dissipated in a radiation attenuation mode, fluorescence is enhanced, and viscosity detection of the mask essence with the main component being water is achieved based on the principle. According to the present invention, the method has characteristics of simple synthesis, stable property, no interference of solvent polarity during detection, long-term storage and long-term use, rapid and high-specificity viscosity response ability, and quantitative analysis of viscosity.

Description

Technical Field

[0001] The invention relates to the field of viscosity detection, and in particular to an auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence and a preparation method thereof. Background Art

[0002] With socioeconomic development, people's pursuit of beauty has intensified, driving the rapid growth of the cosmetics market and the booming beauty industry. Facial masks, a common skincare product, have seen a sustained growth in market size, particularly with the rise of live-streaming e-commerce, which has broadened sales channels and reached a wider consumer base. Common facial masks on the market typically contain highly concentrated serums composed of water, moisturizers, thickeners, preservatives, and functional ingredients, touted as whitening, spot-lightening, and acne-removing. However, to reduce costs, some unscrupulous vendors use water and thickeners as primary ingredients in their facial masks. These products are not only ineffective but may also cause allergic reactions such as redness, itching, and stinging. Long-term use of these products with excessive amounts of thickeners can cause skin to become rough and lack elasticity, and even accelerate the aging process. Some thickeners can form a film-like barrier on the skin's surface, hindering normal respiration and excretion, leading to clogged pores and increased acne breakouts. Thickeners commonly added to facial mask essences include xanthan gum, carbomer, and hydroxyethyl cellulose, typically at levels of 0.1% to 1.0%. Currently, methods for determining the thickener content in facial mask essences rely primarily on ingredient analysis or viscosity testing, but these methods require specialized expertise and instrumentation. Therefore, there is an urgent need for a convenient and rapid analytical method for measuring the viscosity of facial mask essences.

[0003] As a non-destructive analytical detection method, fluorescent probe analysis technology has many advantages, such as easy probe preparation, simple and rapid operation, high selectivity and sensitivity. There are many design ideas for fluorescent probes, among which twisted intramolecular charge transfer (TICT) refers to a special fluorescent molecule in a low-viscosity solvent where the molecular single bond is twisted, resulting in the initial excited state energy being converted into heat without emitting fluorescence, forming a very effective non-radiative channel and fluorescence quenching. However, when this twisting motion is hindered by the surrounding microenvironment (for example, increased viscosity), it will lead to an increase in the fluorescence emission efficiency of the molecule and enhanced fluorescence. Therefore, the fluorescence intensity of molecules with TICT is closely related to viscosity.

[0004] At present, the research related to the use of fluorescent probes to detect viscosity involves the fields of food, industrial products and biochemistry. Chinese patent CN114213388A "The use of fluorescent probes based on thiophene compounds in detecting polarity and viscosity values" studies a fluorescent probe based on thiophene compounds that can detect polarity and viscosity values, but the probe is insoluble in water and not easy to disperse in water. In addition, this dual-response probe is easily interfered by other factors under complex detection conditions, which limits its accurate detection of viscosity in highly polar aqueous environments. Chinese patent CN112898963A "A fluorescent probe for detecting viscosity and its preparation method and application" prepares a fluorescent probe with long-wave emission performance, large Stokes shift and low biological toxicity that can be used for viscosity measurement in solution systems or biological systems. However, the synthesis of the probe molecule is complex, and the polarity of the solvent has a great influence on its fluorescence emission, which will interfere with the viscosity detection in highly polar aqueous environments. Chinese patent CN113913182A, "A fluorescent probe for detecting the viscosity of cosmetic deterioration, its preparation method, and its application," synthesized a 2-((4'-(bis(4-methoxyphenyl)amino)-3-hydroxy-[1,1'-biphenyl]-4-yl)methylene)malononitrile probe, which exhibits aggregation-induced emission (TIEL) properties, highly sensitive responses to viscosity, and is unaffected by interference from solvents of varying polarity. However, the probe molecule is insoluble in water and aggregates and emits light in the aqueous phase, limiting its ability to detect viscosity in highly polar aqueous environments. Therefore, it is of great significance to develop a fluorescent probe that is simple to prepare, exhibits TICT properties, exhibits good solubility or dispersibility in highly polar aqueous environments, and exhibits high sensitivity for use in detecting the viscosity of facial mask essences. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a goldamine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence. The probe is simple to prepare, can achieve efficient, sensitive and rapid detection of viscosity, and can estimate the amount of thickener added in the facial mask essence based on the fluorescence intensity.

[0006] The present invention aims to provide a fluorescent probe that is simple to prepare, has TICT characteristics, and has good water solubility in a highly polar aqueous environment, and to provide an application of the fluorescent probe in the field of viscosity detection.

[0007] The purpose of the present invention is achieved by at least one of the following technical solutions.

[0008] The present invention provides a fluorescent probe for detecting the viscosity of facial mask essence, wherein the fluorescent probe is auramine hydrochloride fluorescent probe (abbreviated as AMO), and the molecular structure is as follows:

[0009]

[0010] The present invention provides a method for preparing an auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essences. The synthetic route is as follows:

[0011]

[0012] The present invention provides a method for preparing an auramine hydrochloride fluorescent probe for detecting the viscosity of a facial mask essence, which specifically comprises the following steps:

[0013] 4,4'-(Iminomethylene)bis(N,N-dimethylaniline) was added to dichloromethane and stirred until completely dissolved. Concentrated hydrochloric acid was slowly added to the solution and stirred at room temperature to react until crystals precipitated. After the reaction, an orange-red solid was obtained by filtration, which was washed with dichloromethane and vacuum dried to obtain an orange-red powdery solid, which is the auramine hydrochloride fluorescent probe.

[0014] Preferably, the molar ratio of the 4,4'-(iminomethylene)bis(N,N-dimethylaniline) to hydrogen chloride is 1:(3-5).

[0015] Preferably, the concentration of the 4,4'-(iminomethylene)bis(N,N-dimethylaniline) dissolved in dichloromethane is 1 mmol / L to 3 mmol / L.

[0016] Preferably, the stirring reaction time is 30-60 min.

[0017] Preferably, the vacuum drying temperature is 25-40° C. and the time is 4-8 hours.

[0018] The principle behind the present invention is that in low-viscosity solvents, the phenyl rings in auramine hydrochloride can rotate unimpeded, dissipating their excited-state energy through nonradiative transitions. This results in weak fluorescence under TICT. However, as viscosity increases, this rotational motion is hindered, weakening the nonradiative energy dissipation and gradually increasing fluorescence, enabling applications in viscosity measurement.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The fluorescent probe prepared by the present invention has TICT characteristics and has a large number of freely rotatable phenyl rings, which can sensitively detect viscosity and characterize the change in viscosity through changes in fluorescence intensity.

[0021] (2) The fluorescent probe prepared by the present invention is prepared by a one-step method and can react at room temperature. The preparation method is simple, efficient and low-cost, and can be applied to large-scale industrial production.

[0022] (3) The fluorescent probe prepared by the present invention has strong anti-interference ability, does not respond to some ions that may exist in the aqueous phase, is not interfered by solvents of different polarities, responds quickly and has strong photostability.

[0023] (4) The fluorescent probe prepared by the present invention has excellent water solubility and is sensitive to the viscosity after adding the thickener xanthan gum, and can be well applied to the viscosity detection of facial mask essence. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the Fourier transform infrared spectrum of auramine hydrochloride.

[0025] Figure 2 These are the fluorescence spectra of the fluorescent probe AMO in systems with different viscosities (the viscosity of the system is adjusted by changing the volume fractions of glycerol and water).

[0026] Figure 3 This is the linear fitting diagram of the fluorescence intensity of the fluorescent probe AMO at 505nm and the logarithmic function of viscosity in different viscosity systems.

[0027] Figure 4 Fluorescence spectra of the fluorescent probe AMO in different solvents.

[0028] Figure 5 This is the selectivity test diagram of the fluorescent probe AMO.

[0029] Figure 6 This is the linear fitting graph of the logarithmic function of the fluorescence intensity of the fluorescent probe AMO at 505 nm in the mask essence and the viscosity.

[0030] Figure 7 This is the photostability diagram of the fluorescent probe AMO in the mask essence.

[0031] Figure 8 This is the linear fitting graph of the fluorescence intensity and mass concentration of the fluorescent probe AMO at 505 nm in the xanthan gum solution, a thickener of the facial mask essence. DETAILED DESCRIPTION

[0032] To further understand the present invention, the method for detecting the viscosity of facial mask essences provided by the present invention is described in detail below with reference to the examples. However, the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are readily achievable or understood by those skilled in the art with reference to the prior art. Reagents or instruments used without manufacturer identification are considered to be commercially available conventional products.

[0033] Example 1

[0034] Dissolve 5.1 mg of 4,4'-(iminomethylene)bis(N,N-dimethylaniline) in 20 mL of dichloromethane (1 mmol / L). Slowly add 5 μL of concentrated hydrochloric acid at 3 mmol / L (hydrochloric acid concentration after addition). Stir at room temperature for 30 minutes. Crystals will form on the walls and bottom of the cup, yielding auramine hydrochloride. The solution pH is 3. After the reaction, filter and wash the precipitate several times with dichloromethane. Dry under vacuum at 25°C for 4 hours to obtain 5.2 mg of an orange-red powdery solid, the auramine hydrochloride fluorescent probe (85.0% yield).

[0035] Figure 1 The main infrared spectrum data of auramine hydrochloride are shown in Figure 2. -1 There is a stretching vibration peak of NH at 818 cm -1 =NH2 + The in-plane swing peak of 1159cm indicates that the imino group forms an amine salt. -1 There is a stretching vibration peak of CN at 2991cm -1 There is N + -CH3 antisymmetric stretching vibration peak indicates the formation of tertiary amine salt. The above infrared spectrum analysis can confirm that the synthesized product is the target fluorescent probe.

[0036] Example 2

[0037] Dissolve 10.2 mg of 4,4'-(iminomethylene)bis(N,N-dimethylaniline) in 20 mL of dichloromethane (2 mmol / L). Slowly add 13.5 μL of concentrated hydrochloric acid at 8 mmol / L. Stir the mixture at room temperature for 45 minutes. Crystals will form on the walls and bottom of the cup, yielding auramine hydrochloride. The pH of the solution is 2.5. After the reaction, filter and wash the precipitate several times with dichloromethane. Dry under vacuum at 30°C for 6 hours to obtain 10.6 mg of an orange-red powdery solid (87.6% yield), the auramine hydrochloride fluorescent probe.

[0038] The characterization results of the fluorescent probe obtained in this example are the same as those in Example 1.

[0039] Example 3

[0040] Dissolve 15.3 mg of 4,4'-(iminomethylene)bis(N,N-dimethylaniline) in 20 mL of dichloromethane (3 mmol / L). Slowly add 25.5 μL of concentrated hydrochloric acid at 15 mmol / L. Stir the mixture at room temperature for 60 minutes. Crystals will form on the wall of the cup, yielding auramine hydrochloride. The pH of the solution is 2. After the reaction, filter and wash the precipitate several times with dichloromethane. Dry under vacuum at 40°C for 8 hours to obtain 15.7 mg of an orange-red powdery solid, the auramine hydrochloride fluorescent probe (86.4% yield).

[0041] The characterization results of the fluorescent probe obtained in this example are the same as those in Example 1.

[0042] Example 4

[0043] Fluorescent probe AMO response test to viscosity:

[0044] The fluorescent probe AMO prepared in Example 1 was dissolved in a mixed solution of glycerol / water with different volume ratios to conduct a viscosity response test. The concentration of the fluorescent probe was maintained at 20 μM, the total volume of the test solution was maintained at 3.0 mL, and the excitation wavelength was 430 nm. The viscosity of the system was changed by changing the volume fraction of glycerol. The viscosity response fluorescence spectra in mixed solutions with glycerol volume percentages of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 99% were tested respectively. The obtained fluorescence spectra are shown in the figure below. Figure 2 At room temperature, the viscosities of the ten test systems were 1.0 cP, 1.5 cP, 2.0 cP, 3.2 cP, 4.7 cP, 9.0 cP, 15.2 cP, 35.5 cP, 90.0 cP, 310.0 cP, and 1410.0 cP, respectively. The logarithm of the fluorescence intensity at 505 nm was plotted against the logarithm of the viscosity, as shown in the figure. Figure 3 As shown. Figure 2 It can be seen that as the volume fraction of glycerol in the solution increases, the fluorescence intensity of the solution gradually increases. This is because the increase in viscosity hinders the rotation of the phenyl ring in the fluorescent probe AMO molecule, and the excited state energy originally dissipated through non-radiative transitions is dissipated through radiative transitions, and the fluorescence signal gradually increases. Figure 3 As can be seen from the figure, the logarithm of the fluorescence intensity of the fluorescent probe at 505 nm and the logarithm of the solution viscosity show a good linear relationship. That is, as the viscosity increases, the fluorescence intensity also gradually increases, indicating that the fluorescent probe AMO has good sensitivity to viscosity. These test results indicate that the fluorescent probe AMO is suitable for measuring the viscosity of facial mask essences.

[0045] Example 5

[0046] Fluorescence test of fluorescent probe AMO in different solvents:

[0047] The fluorescent probe AMO prepared in Example 1 was tested for fluorescence in different solvents. The solvents included: water, ethanol, ethyl acetate, dioxane, dimethyl sulfoxide, methanol, acetonitrile, and 99% glycerol + 1% water. The concentration of the fluorescent probe AMO was kept at 20 μM, the total volume was kept at 3.0 mL, and the excitation wavelength was 430 nm. The fluorescence spectrum obtained by the test is shown in the figure below. Figure 4 As shown, from Figure 4 It can be seen that the fluorescent probe is almost unaffected in the atmosphere of solvents of different polarities, and only has a good fluorescence response to 99% propylene glycol + 1% water with higher viscosity, indicating that the fluorescent probe is suitable for detecting the viscosity of facial mask essences with complex solvent systems.

[0048] Example 6

[0049] Selectivity test of fluorescent probe AMO:

[0050] The fluorescent probe AMO prepared in Example 1 was dissolved in water to prepare a probe mother solution with a probe concentration of 2mM. Some detected objects including NaCl, Na4P2O7, Na2SO3, NaNO3, CH3COONa, K2CO3, CaCl2, and ZnSO4 were dissolved in deionized water to obtain corresponding solutions (viscosity values ​​were all less than 2cP), and 30μL of the probe mother solution was added to the solutions of the above-mentioned detected objects. Similarly, 30μL of the probe mother solution was added to 2.97mL of glycerol to prepare a glycerol (containing 1% water) test sample. During the test, the concentration of the fluorescent probe AMO was kept at 20μM in different samples to be tested, the concentration of each detected object was 100μM, the total volume of each group of test samples was kept at 3.0mL, and the wavelength of 430nm was used as the excitation wavelength. The fluorescence spectrum obtained by the test is shown as follows Figure 5 As shown, from Figure 5 It can be seen that the fluorescence intensity of the fluorescent probe AMO does not change significantly in the presence of various analytes. A significant increase in fluorescence intensity can only be observed in a viscous propylene glycol solution (containing 1% water), indicating that only changes in viscosity can cause changes in fluorescence intensity. This fluorescent probe has strong anti-interference ability and is suitable for use in highly polar aqueous solution environments containing multiple components.

[0051] Example 7

[0052] Estimating the viscosity of facial mask essence using the falling ball method:

[0053] Six different facial mask essences were selected for viscosity testing. 10 mL of facial mask essence was placed in a glass cylinder. A small ball with a diameter of 3 mm was dropped along the central axis of the glass cylinder with an inner diameter of 20 mm. The time t and distance L of the drop were recorded. The mass of the test liquid and the ball was weighed, and the density of the test liquid and the density of the ball were calculated. The viscosity can be calculated by the formula Calculated, where g is the local acceleration due to gravity. Three parallel experiments were conducted for each facial mask essence, and the average value was used as the viscosity of the mask essence. The falling ball method for measuring liquid viscosity is based on the principle that when a small ball falls freely in a liquid, it is affected by gravity and viscous forces, and its falling speed is affected by the viscosity. According to Stokes' law, the falling speed of the ball is directly proportional to the viscosity and inversely proportional to the radius, density, and density of the liquid. Therefore, the experimentally measured viscosity of the mask essence has a certain degree of reliability.

[0054] Example 8

[0055] Response test of fluorescent probe AMO to the viscosity of facial mask essence:

[0056] The fluorescent probe AMO prepared in Example 1 was dissolved in water to prepare a probe mother solution with a probe concentration of 2 mM. 30 μL of the probe mother solution was added to 2.97 mL of the mask essence to prepare a mask essence test sample. During the test, the concentration of the fluorescent probe AMO was kept at 20 μM in different test samples. The total volume of each group of test samples was kept at 3.0 mL. The excitation wavelength was 430 nm, and the logarithm of the fluorescence intensity at 505 nm was plotted against the logarithm of the mask essence viscosity measured in Example 7, as shown in FIG. Figure 6 As shown. Figure 6 It can be seen that the greater the viscosity of the mask essence, the greater the fluorescence intensity, indicating that the fluorescent probe AMO can evaluate the viscosity level of the mask essence by fluorescence intensity.

[0057] Example 9

[0058] Photostability test of fluorescent probe AMO in facial mask essence:

[0059] The fluorescent probe AMO prepared in Example 1 was dissolved in water to prepare a probe mother solution with a probe concentration of 2 mM. 30 μL of the fluorescent probe mother solution was added to 2.97 mL of the facial mask essence to prepare a facial mask essence test sample. The concentration of the fluorescent probe AMO in the test sample was 20 μM. The total volume of the test sample was 3.0 mL. The excitation wavelength was 430 nm. The test was performed every 15 minutes. The fluorescence intensity at 505 nm was plotted against time. Figure 7As shown in the figure, the fluorescence of the probe remained stable in the facial mask essence from 0 to 90 minutes, indicating that the fluorescent probe has good photostability. During the test, the fluorescent probe TT showed good water solubility in the test solution (no flocculation or precipitation was observed), indicating that the probe molecule has good water solubility in a highly polar environment.

[0060] Example 10

[0061] Viscosity response test of fluorescent probe AMO on xanthan gum solution, a thickener in facial mask essence:

[0062] The fluorescent probe AMO prepared in Example 1 was dissolved in water to prepare a probe mother solution with a probe concentration of 2mM. Xanthan gum with a mass concentration of 0g / kg, 1g / kg, 2g / kg, 3g / kg, and 4g / kg was added to a mixed solution of water (85%), butanediol (10%), and glycerol (5%) to simulate the thickening system of the facial mask essence. During the test, 30μL of the probe mother solution was added to the xanthan gum solutions containing different mass concentrations, and the concentration of the fluorescent probe was controlled to be 20μM. The total volume of each test sample was 3mL. The test was carried out at room temperature, and the excitation wavelength was set to 430nm. The fluorescence intensity of the fluorescent probe at 505nm in the xanthan gum solution was plotted against the mass concentration, as shown in FIG. Figure 8 As shown in the figure, as the concentration of xanthan gum increases, the solution changes from a fluid state to a semi-jelly state, reflecting the viscosity increase process of the mask essence with different thickener addition amounts. Figure 8 It can be seen that the fluorescence intensity of the fluorescent probe AMO increases with the increase of the mass concentration of xanthan gum, indicating that the fluorescent probe has a high response sensitivity to changes in liquid viscosity and can feedback the change process of solution viscosity through changes in fluorescence signals, which is of great significance for the detection of the physical indicator of mask essence viscosity.

Claims

1. A goldamine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence, characterized in that: The structural formula of the fluorescent probe is as follows:

2. A method for preparing auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence according to claim 1, characterized in that: The synthetic route is as follows:

3. A method for preparing auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence according to claim 2, characterized in that, The following steps are involved: 4,4'-(Iminomethylene)bis(N,N-dimethylaniline) was added to dichloromethane and stirred until completely dissolved. Concentrated hydrochloric acid was then added to the solution and stirred at room temperature until crystals precipitated. After the reaction, an orange-red solid was obtained by filtration, which was washed with dichloromethane and vacuum dried to obtain an orange-red powdery solid, which is the auramine hydrochloride fluorescent probe.

4. A method for preparing auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence according to claim 3, characterized in that, The pH of the solution is 2-3 when crystals are precipitated.

5. A method for preparing auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence according to claim 3, characterized in that, The molar ratio of the 4,4'-(iminomethylene)bis(N,N-dimethylaniline) to HCl is 1:(3-5).

6. A method for preparing auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence according to claim 3, characterized in that, The concentration of the 4,4'-(iminomethylene)bis(N,N-dimethylaniline) dissolved in dichloromethane is 1 mmol / L to 3 mmol / L.

7. The method for preparing auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence according to claim 3, wherein The time for the reaction after the dropwise addition of concentrated hydrochloric acid and stirring at room temperature is 30-60 minutes.

8. The method for preparing auramine hydrochloride fluorescent probe for detecting the viscosity of facial mask essence according to claim 3, wherein The vacuum drying temperature is 25-40° C. and the time is 4-8 hours.

9. Use of the auramine hydrochloride fluorescent probe according to claim 1 in detecting the viscosity of facial mask essence.

10. The use according to claim 9, characterized in that This fluorescent probe can release a strong fluorescence signal at 505nm under an excitation wavelength of 430nm.

Images