Fluorescent probe for detecting pyroglutamyl aminopeptidase I and preparation method and application thereof
阅读说明：本技术 一种用于检测焦谷氨酰氨基肽酶i的荧光探针及其制备方法与应用 (Fluorescent probe for detecting pyroglutamyl aminopeptidase I and preparation method and application thereof ) 是由 柏桦 方斌 李林 彭勃 胡文博 姚传好 于海东 傅莉 黄维 于 2021-10-25 设计创作，主要内容包括：本发明公开了一种用于检测焦谷氨酰氨基肽酶I的荧光探针及其制备方法与应用,方法包括：LXY、HATU和DIPEA混合,完全溶解在干燥的二氯甲烷溶液中,在0℃下搅拌反应；再加入TPAN溶液,进一步室温搅拌反应,结束后进行纯化,得到为深红色固体BH1-BOC；将BH1-BOC溶解在无水二氯甲烷中,在冰盐浴条件下,加入配好的三氟乙酸溶液,滴加完毕进行室温搅拌反应；旋干溶剂,再向其中加入二氯甲烷,反复多次,直到将三氟乙酸全部旋干；将粗产物通纯化,得到红色固体BH1。(The invention discloses a fluorescent probe for detecting pyroglutamyl aminopeptidase I and a preparation method and application thereof, wherein the method comprises the following steps: mixing LXY, HATU and DIPEA, completely dissolving in dry dichloromethane solution, and stirring at 0 deg.C for reaction; adding TPAN solution, further stirring and reacting at room temperature, and purifying to obtain deep red solid BH 1-BOC; dissolving BH1-BOC in anhydrous dichloromethane, adding a prepared trifluoroacetic acid solution under the condition of ice salt bath, and stirring at room temperature to react after dropwise addition; spin-drying the solvent, adding dichloromethane, and repeating for multiple times until all trifluoroacetic acid is spin-dried; the crude product was purified to afford BH1 as a red solid.)
1. A fluorescent probe for detecting pyroglutamyl aminopeptidase I, which is characterized in that the structural formula of the fluorescent probe is as follows:
2. the fluorescent probe for detecting pyroglutamyl aminopeptidase I as claimed in claim 1, wherein the optimal absorption/emission wavelengths of the fluorescent probe and dye TPAN in PBS buffer solution are 300/408nm and 321/513nm respectively, when excited at 300nm, the fluorescent probe shows grass blue emission, the peak value is reached at 0-408 nm, and the two-photon absorption cross section is 12.4 GM; the dye has green fluorescence emission at 513nm and a two-photon absorption cross section of 188.0 GM.
3. The method for synthesizing a fluorescent probe for detecting pyroglutamylaminopeptidase I as claimed in claim 1, comprising the steps of:
mixing LXY, HATU and DIPEA, completely dissolving in dry dichloromethane solution, and stirring at 0 deg.C for reaction; adding TPAN solution, further stirring and reacting at room temperature, and purifying to obtain deep red solid BH 1-BOC;
dissolving BH1-BOC in anhydrous dichloromethane, adding a prepared trifluoroacetic acid solution under the condition of ice salt bath, and stirring at room temperature to react after dropwise addition; spin-drying the solvent, adding dichloromethane, and repeating for multiple times until all trifluoroacetic acid is spin-dried; the crude product was purified to afford BH1 as a red solid.
4. The method for synthesizing a fluorescent probe for detecting pyroglutamyl peptidase I according to claim 3, wherein the molar ratio of LXY, HATU and DIPEA is 1:1: 2.5;
the TPAN solution is obtained by dissolving TPAN in dichloromethane, and the dosage ratio of TPAN to dichloromethane is 1 mmol: 10 mL.
5. The method for synthesizing a fluorescent probe for detecting pyroglutamyl aminopeptidase I as claimed in claim 3, wherein the purification is performed after the end, specifically comprising:
carrying out reduced pressure distillation, drying the solvent by spinning, purifying the crude product by silica gel chromatography, and using petroleum ether/ethyl acetate as an eluent to obtain BH 1-BOC; the volume ratio of the petroleum ether to the ethyl acetate is (30-1): 1.
6. the method for synthesizing a fluorescent probe for detecting pyroglutamyl aminopeptidase I as claimed in claim 3, wherein the trifluoroacetic acid solution is prepared by dissolving trifluoroacetic acid in dichloromethane, and the volume ratio of trifluoroacetic acid to dichloromethane is 2: 3.
7. The method for synthesizing a fluorescent probe for detecting pyroglutamyl peptidase I according to claim 3, wherein said reaction is terminated after confirming the complete removal of the protecting group by dot plate tracing in the reaction of stirring at room temperature after completion of the addition.
8. The method for synthesizing a fluorescent probe for detecting pyroglutamyl aminopeptidase I as claimed in claim 3, wherein the crude product is purified, and the method comprises the following steps:
the crude product was purified by flash chromatography on silica gel with dichloromethane/methanol as eluent to afford BH1 as a red solid.
9. The method for synthesizing a fluorescent probe for detecting pyroglutamyl aminopeptidase I as claimed in claim 3, wherein the volume ratio of dichloromethane/methanol is 10/1.
10. Use of the fluorescent probe for detecting pyroglutamyl aminopeptidase I as defined in claim 1 for the detection and imaging of PGP-1 in a biological sample.
Technical Field
The invention belongs to the field of small molecule fluorescent probe analysis and detection, and particularly relates to a fluorescent probe for detecting pyroglutamyl aminopeptidase I (PGP-1), and a preparation method and application thereof.
Background
Pyroglutamylaminopeptidase I (PGP-1, EC 3.4.19.3) is a typical cytoplasmic cysteine peptidase. PGP-1 is widely distributed in bacterial, plant and animal tissues and can specifically hydrolyze L-pyroglutamic acid (L-pGlu) residues from the amino terminus of endogenous proteins and bioactive peptides (via hypotensive, luteinizing hormone-releasing hormone, gastrin, thyroid hormone-releasing hormone, and immunoglobulins, etc.). Thus, PGP-1 had a significant effect in determining the amino terminal sequences of N-blocking peptides and proteins containing L-pGlu residues. The enzyme catalysis product L-pGlu also has a plurality of pharmacological properties, and mainly comprises excitatory amino acid antagonist, brain stimulant, anxiety agent and the like. Related studies have shown that PGP-1 is involved in the immune response in cells and is involved in intracellular inflammatory responses as a novel inflammatory factor. However, past studies were limited to cell and live mouse levels, and the pathological and physiological properties of model mice remained largely different from those of humans, and thus, there was a lack of evaluation of the differences in PGP-1 activity in human samples and demonstration of involvement in inflammatory responses in human samples. This would greatly limit the understanding of the exact role of PGP-1 in the metabolism of anti-inflammatory drugs. Therefore, the development of effective small-molecule fluorescent probes for exploring PGP-1 and the pathogenesis of clinical body inflammation and some diseases is urgently needed. At present, the existing PGP-1 fluorescent probe is only suitable for a short-wave excited single-photon fluorescence microscopy, and due to the fact that the existing PGP-1 fluorescent probe is greatly interfered by the background and weak in tissue infiltration capacity, the application of the probe in organisms is limited. Bioimaging of two-photon excited (TPE) fluorescent probes allows for improved three-dimensional localization and increased imaging depth compared to conventional single photon fluorescent probes, and reduces phototoxicity or photodamage to biological samples, thus making detection of PGP-1 activity in living tissue more advantageous. However, a two-photon fluorescent probe with specificity for detecting PGP-1 in a clinical human sample has not been reported yet, and there is a need for research.
Disclosure of Invention
In order to solve the problems, the invention provides a fluorescent probe for detecting pyroglutamyl peptidase I and a preparation method and application thereof, wherein a novel two-photon fluorescent probe (BH1) is designed by introducing L-pGlu into the skeleton of a naphthalene ring fluorophore. The probe has excellent effective two-photon absorption cross section (lambda ex is 760 nm; delta phi is 118GM) after reacting with PGP-1, shows excellent selectivity and responsiveness to PGP-1 under physiological conditions, and is also suitable for the research of the imaging field of PGP-1 in different biological samples.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a fluorescent probe for detecting pyroglutamylaminopeptidase I, which has a structural formula as follows:
as a further improvement of the invention, the optimal absorption/emission wavelengths of the fluorescent probe and the dye TPAN in the PBS buffer solution are 300/408nm and 321/513nm respectively, when the dye TPAN is excited by 300nm, the fluorescent probe shows grass cyan emission, the peak value is reached at 0-408 nm, and the two-photon absorption cross section is 12.4 GM; the dye has green fluorescence emission at 513nm and a two-photon absorption cross section of 188.0 GM.
A method for synthesizing a fluorescent probe for detecting pyroglutamylaminopeptidase I, comprising the following steps:
mixing LXY, HATU and DIPEA, completely dissolving in dry dichloromethane solution, and stirring at 0 deg.C for reaction; adding TPAN solution, further stirring and reacting at room temperature, and purifying to obtain deep red solid BH 1-BOC;
dissolving BH1-BOC in anhydrous dichloromethane, adding a prepared trifluoroacetic acid solution under the condition of ice salt bath, and stirring at room temperature to react after dropwise addition; spin-drying the solvent, adding dichloromethane, and repeating for multiple times until all trifluoroacetic acid is spin-dried; the crude product was purified to afford BH1 as a red solid.
As a further improvement of the invention, the molar ratio of LXY, HATU and DIPEA is 1:1: 2.5;
the TPAN solution is obtained by dissolving TPAN in dichloromethane, and the dosage ratio of TPAN to dichloromethane is 1 mmol: 10 mL.
As a further improvement of the present invention, the purification after the completion specifically includes:
carrying out reduced pressure distillation, drying the solvent by spinning, purifying the crude product by silica gel chromatography, and using petroleum ether/ethyl acetate as an eluent to obtain BH 1-BOC; the volume ratio of the petroleum ether to the ethyl acetate is (30-1): 1.
as a further improvement of the invention, the trifluoroacetic acid solution is prepared by dissolving trifluoroacetic acid in dichloromethane, and the volume ratio of the trifluoroacetic acid to the dichloromethane is 2: 3.
As a further improvement of the invention, during the stirring reaction at room temperature after the completion of the dropwise addition, the reaction is terminated after the complete removal of the protecting group is determined by adopting point plate tracking.
As a further improvement of the present invention, the purifying the crude product specifically comprises:
the crude product was purified by flash chromatography on silica gel with dichloromethane/methanol as eluent to afford BH1 as a red solid.
As a further improvement of the invention, the volume ratio of dichloromethane/methanol is 10/1.
The fluorescent probe for detecting pyroglutamyl aminopeptidase I is applied to the detection and imaging of PGP-1 in a biological sample.
Compared with the prior art, the method has the following technical effects and advantages:
the synthesized small molecular fluorescent probe BH1 is a biosensing material with excellent photophysical properties and good biocompatibility;
the target product synthesized by the method has the advantages of easily available raw materials, low cost, simple synthesis steps and good solubility, and the commercialization of the target product becomes possible.
The synthesized target product has diester functional groups and has good cell membrane permeability, and in addition, BH1 can also be used as a two-photon fluorescent probe, the excitation wavelength of the probe is in a near infrared region of 760nm, and the probe has the advantages of lower excitation energy, stronger permeability, less light damage to cells and the like; the response of the probe to PGP-1 is in a linear relation, and the probe can be used for quantitative detection of the enzyme; the probe has high sensitivity response to PGP-1, and can be used for trace detection of the enzyme; the response of the probe to PGP-1 is not influenced by the interference of common inorganic salt, protein, amino acid and the like in organisms; the probe has good solubility, and can be directly used for detecting and imaging PGP-1 in a biological sample;
drawings
FIG. 1 is a diagram of the chemical reaction equation and synthetic scheme for compound BH1 of the present invention;
FIG. 2 is a graph comparing single photon emission spectra (FIG. 2A) and two-photon fluorescence spectra (FIG. 2B) of probes and dyes of the present invention;
FIG. 3 is a graph showing the fluorescence emission spectrum of probe BH1 of the present invention as a function of the concentration of PGP-1 in an in vitro assay; the embedded graph is as follows: when the concentration of the PGP-1 is within a certain range, the linear relation of the probe to the PGP-1 is shown schematically;
FIG. 4 is a kinetic study of the probe of the present invention on PGP-1; the embedded graph is as follows: a schematic view of a fitted linewerver-Burk curve;
FIG. 5 is a schematic diagram of the probe of the present invention detecting PGP-1 in phagocytic RAW264.7 cells, inducing intracellular up-regulation of PGP-1 by LPS, and inducing expression down-regulation of PGP-1 by siPGP-1;
FIG. 6 is a schematic diagram of the probe of the present invention detecting PGP-1 expression in skin tissue of a patient with clinical inflammation by two-photon confocal fluorescence microscopy;
FIG. 7 is a graph showing the evaluation of PGP-1 expression in clinical serum samples using the probe of the present invention, and the expression of other inflammatory factors (L-6, TNF-. alpha.and PCT) in test serum samples.
Detailed Description
The invention aims to provide a fluorescent probe for detecting pyroglutamyl aminopeptidase I and a preparation method and application thereof.
The invention provides a compound BH1, which has a structural formula as follows:
first, the photophysical properties of the probe were evaluated. The optimal absorption/emission wavelengths of needle BH1 and dye TPAN in PBS buffered solution were measured to be 300/408nm,321/513nm, respectively (fig. 2A). When the excitation is carried out at 300nm, BH1 shows grass cyan emission, the peak value is reached at 408nm, and the two-photon absorption cross section is 12.4 GM; the dye has stronger green fluorescence emission at 513nm and larger two-photon absorption cross section of 188.0GM (figure 2B).
A method for synthesizing a fluorescent probe for detecting pyroglutamylaminopeptidase I, comprising the following steps:
mixing LXY, HATU and DIPEA, completely dissolving in dry dichloromethane solution, and stirring at 0 deg.C for reaction; adding TPAN solution, further stirring and reacting at room temperature, and purifying to obtain deep red solid BH 1-BOC;
dissolving BH1-BOC in anhydrous dichloromethane, adding a prepared trifluoroacetic acid solution under the condition of ice salt bath, and stirring at room temperature to react after dropwise addition; spin-drying the solvent, adding dichloromethane, and repeating for multiple times until all trifluoroacetic acid is spin-dried; the crude product was purified to afford BH1 as a red solid.
The PGP-1 detection capability of the probe is evaluated in vitro; after the probe is added with PGP-1 by taking 350nm as excitation, the fluorescence spectrum of the probe can be obviously changed. Probe BH1 showed good linearity over the PGP-1 range of 0.01-2.0 μ g/mL, with the equation Δ F1641.9 x C (μ g/mL) +11.24 (R0.996), and the detection limit of BH1 for PGP-1 was calculated to be 2.64ng/mL (fig. 3).
The kinetic behavior of the probe on PGP-1 was studied according to Michaelis-Menten equation and the corresponding Michaelis constant (Km: 8.996 μ M, kcat: 0.38min-1, Vmax: 0.11nmol mg-1 min-1) was obtained (fig. 4), thus demonstrating the high affinity of the probe for PGP-1. BH1 has high selectivity and high sensitivity to PGP-1 action, and can be used as a good PGP-1 response two-photon probe for various biological field researches.
Detecting the change of intracellular PGP-1 through a probe BH1, and exploring the relation between PGP-1 and the immune process; flow cytometry results clearly reflected up-and down-regulation of intracellular PGP-1 concentration by treatment of RAW264.7 cells with immunopotentiator Lipopolysaccharide (LPS) and siRNA perturbation (siPGP-1), and were further confirmed by subsequent Western Blot (Western Blot, WB) and Polymerase Chain Reaction (PCR) analysis. To some extent, it was demonstrated that PGP-1 could be a novel inflammatory cytokine indicative of inflammation. Then, after the fluorescence intensity is obviously observed to be obviously higher than that of the RAW264.7 cells treated by the LPS in the control group through laser confocal; RAW264.7 transfected with siRNA had a weaker intracellular fluorescence intensity than the control group, and the cells treated with siRNA were transfected (fig. 5). This increase and decrease in fluorescence reflects the level of endogenous PGP-1 expression, consistent with the WB and PCR results. Unlike conventional PGP-1 assays, which require physical isolation of the PGP-1 protein, BH1 provides an efficient method for reporting endogenous PGP-1 activity expression by confocal microscope visualization.
After demonstrating that PGP-1 can be used as a novel inflammatory factor and that the probe can detect the activity of intracellular PGP-1 with high specificity, the present invention is highly expected to evaluate whether the probe can be used for detecting the high level of PGP-1 activity in clinically relevant inflammation by a highly efficient method. Therefore, the invention continues to explore the application of the probe BH1 in the detection of the endogenous PGP-1 of the clinical living tissue. The invention uses a probe to treat skin tissue from a burn patient (inflammation occurrence) and normal skin tissue of the same patient, and explores PGP-1 activity in deep tissues by TPFM imaging technology. As shown in FIG. 6, the fluorescence intensity of the experimental group (ID1-3) was significantly higher than that of the control group, which means that the occurrence of burn inflammation did result in the up-regulation of PGP-1 expression in human skin tissue.
Blood flows through the organs and tissues of the body, and is a mirror of the organs and tissues. A certain amount of venous blood is collected, and the change of the concentration of the inflammatory factors in the blood can be effectively monitored to be used as one of the basis for diagnosing the inflammation. To this end, seven clinical sepsis patients were collected and the feasibility of PGP-1 activity in serum samples was assessed by probe BH1 and in vitro assays were performed according to standard assay methods. As shown in FIG. 7, the expression of PGP-1 activity detected by the probe was significantly higher in sepsis patients than in the normal group, and importantly, upregulation of IL-6, TNF-. alpha.and PCT (which was associated with enhancement of the inflammatory process of sepsis) was also confirmed by the assay.
The synthesized small molecular fluorescent probe BH1 is a biosensing material with excellent photophysical properties and good biocompatibility;
the target product synthesized by the method has the advantages of easily available raw materials, low cost, simple synthesis steps and good solubility, and the commercialization of the target product is possible;
the synthesized target product has diester functional groups and has good cell membrane permeability, and in addition, BH1 can also be used as a two-photon fluorescent probe, the excitation wavelength of the probe is in a near infrared region of 760nm, and the probe has the advantages of lower excitation energy, stronger permeability, less light damage to cells and the like;
the response of the probe to PGP-1 is in a linear relation, and the probe can be used for quantitative detection of the enzyme;
the probe has high sensitivity response to PGP-1, and can be used for trace detection of the enzyme;
the response of the probe to PGP-1 is not influenced by the interference of common inorganic salt, protein, amino acid and the like in organisms;
the probe has good solubility, and can be directly used for detecting and imaging PGP-1 in a biological sample;
the invention firstly evaluates the activity difference of PGP-1 in a human sample by utilizing the probe and proves that the PGP-1 is involved in inflammatory reaction in a clinical sample.
The invention will be illustrated below with reference to specific examples. In particular, these examples are only intended to illustrate the invention and are not intended to limit the scope of the invention. In practice, the technical personnel according to the invention make improvements and modifications, which still belong to the protection scope of the invention.
Example 1
Synthesis of dimethyl (R) -6- (1- (tert-butoxycarbnyl) -5-oxypyrolidine-2-carboxamido) naphthalene-2,3-dicarboxylate (BH1-BOC)
Dimethyl 6-aminonaphthalene-2, 3-dicarboylate (LXY; 115mg, 0.5mmol), 2- (7-Azabenzotriazol-1-yl) -N, N, N ', N' -tetramethyluronium hexafluorophosphate (HATU; 190mg, 0.5mmol) and N, N-Dipropylamine (DIPEA; 200. mu.L, 1.25mmol) were added to a single-neck flask and completely dissolved in a dry dichloromethane solution (25mL), and the above reactants were stirred at 0 ℃ for 30 minutes. Then, TPAN (130mg, 0.5mmol) dissolved in methylene chloride (5mL) was added thereto, and the mixture was further stirred at room temperature for 4 hours. After the reaction was complete, the solvent was evaporated under reduced pressure, the crude product was purified by silica gel chromatography using petroleum ether/ethyl acetate (15/1, v/v) as eluent to afford BH1-BOC (70mg) as a dark red solid, yield: 14 percent. BH 1-BOC:1H NMR(500MHz,DMSO-d6)δppm:10.80(s,1H),8.44(s,1H),8.36(s,1H),8.24(s,1H),8.13(d,J＝8.7Hz,1H),7.85(d,J＝8.4Hz,1H),4.75(d,J＝6.3Hz,1H),3.86(s,6H),2.38-2.17(m,2H),2.40-2.26(m,2H),1.98(s,2H),1.36(s,9H).13C NMR(125MHz,DMSO-d6)δppm:177.49,172.04,167.79,167.13,139.19,133.80,129.89,129.72,129.37,129.23,128.78,126.05,122.51,115.77,56.49,52.60,29.22,25.33.HRMS:m/z[M+H]+calcd:471.5263,found:470.1689.
synthesis of BH1
Intermediate BH1-BOC (70mg, 0.15mmol) was dissolved in dry dichloromethane (5mL) and the prepared trifluoroacetic acid solution (4mL of trifluoroacetic acid in 6mL of dry dichloromethane) was added slowly dropwise to the system under ice salt bath conditions. Dropwise additionAfter completion, the reaction was stirred at room temperature. And (5) carrying out dot plate tracking, and terminating the reaction after the protective group is completely removed. The solvent is dried by spinning, and dichloromethane is added into the solvent repeatedly until the trifluoroacetic acid is completely dried by spinning. And the crude product was purified by flash chromatography on silica gel with dichloromethane/methanol (10/1, v/v) as eluent to give BH1 as a red solid (50mg) yield: 72 percent. BH1:1H NMR(500MHz,DMSO-d6)δppm:8.96(s,1H),8.17(s,1H),8.05(s,1H),7.99(s,1H),7.69(d,J＝8.7Hz,1H),7.62(d,J＝8.6Hz,1H),7.09(s,1H),4.39(dd,J＝8.3,5.5Hz,1H),3.94(s,3H),3.91(s,3H),2.66(s,1H),2.52(s,1H),2.43(s,1H),2.34(s,1H).13C NMR(125MHz,DMSO-d6)δppm:177.49,172.04,167.79,167.13,139.19,133.80,129.89,129.72,129.37,129.23,128.78,126.05,122.51,115.77,56.49,52.60,29.22,25.33.MS:m/z[M+H]+calcd:370.3610,found:371.2272.
3. absorption/emission spectrum test method and conditions
A defined amount of TPAN and BH1 solid was weighed out and prepared in DMSO as a probe stock solution with a concentration of 5 mM. The stock was diluted to 1 μ M using an enzyme assay buffer solution (composition 10mM PBS, 5% DMSO, pH 7.42) for subsequent testing. In the spectrum test, after the 1 μ M probe was reacted with 5 μ g/mL of PGP-1 for 30 minutes, the absorption spectrum at 280-600nm and the fluorescence emission spectrum at 400-700nm under 325nm excitation were tested.
3.2.1 sensitivity test
After reacting 1 μ M of BH1 with different concentrations of PGP-1(0, 0.2, 0.5, 1, 2,3, 4, 5, 10, 15, 20, 30, 40, 50 μ g/mL) in an enzyme buffer solution at 37 ℃ for 30 minutes, the fluorescence emission spectrum at 400-700nm (λ ex ═ 325nm) was recorded using an instrument.
3.2.2 detection Limit calculation
The linear relationship between PGP-1 concentration (0.2-5 μ g/mL) and the fluorescence intensity of BH1(1 μ M) was calculated, and the linear equation (n ═ 3) was obtained. Using formulas
LOD＝3σ/k (3-1)
And obtaining a detection limit, wherein sigma is the standard deviation of 11 detection results of the blank sample, and k is the slope of the linear relation between the concentration of PGP-1 and the fluorescence intensity.
3.2.6 specificity test
Experimental group 1: probe BH1 (1. mu.M) was reacted with PGP-1 (5. mu.g/mL) for 30 min;
experimental group 2: the inhibitor iodoacetamide (150nM) was used to pre-react with PGP-1(300ng/mL) for 1 h, followed by addition of probe BH1 (1. mu.M) for 30 min
And simultaneously setting blank groups, wherein each group is provided with three parallel samples, and after the reaction is finished, recording a fluorescence emission spectrogram at 4500nm under the excitation of lambda ex-325 nm by using an enzyme-linked immunosorbent assay.
3.2.3 anti-interference test
Accurately weighing a certain amount of anions, cations and amino acids by using a one-tenth-ten-thousandth balance, and preparing stock solution with the concentration of 10mM by using ultrapure water. For the test, the stock solution was diluted to a final concentration of 100. mu.M using an enzyme buffer solution, reacted with probe BH1 (1. mu.M) at 37 ℃ for 30 minutes, and then the fluorescence intensity of the probe at 525nm (. lamda. ex. 325nm) was recorded and compared with the fluorescence intensity of probe BH1 (1. mu.M) and PGP-1 (5. mu.g/mL) for 30 minutes.
The interferent includes: NaCl; KNO3；Mg(NO3)2·6H2O；Al(NO3)3·9H2O；Cu(NO3)2·9H2O；Fe(NO3)3·9H2O；Mn(NO3)2·4H2O；Cd(NO3)2·4H2O；Zn(NO3)2·6H2O；Ni(NO3)2·6H2O；Cr(NO3)3·9H2O；FeCl2·4H2O；Ca(NO3)2·4H2O；CH3COONa；NaHCO3；NaF；NaBr；NaI；NaNO3；Na2CO3；Na2SO4；Na2HPO4·12H2O；NaH2PO4·2H2O；NaClO；Glycine；Alanine；Valine；Isoleucine；Phenylalanine；Tryptophan；Methionine；Proline；Serine；Threonine；Cysteine；Tyrosine；Histidine；Lysine；Arginine；Asparticacid；Glutamicacid.
3.2.4 stability test
(1) pH stability: PBS solutions (10mM, 5% DMSO) were prepared at different pH (4.0-10.0), and probe BH1 (15. mu.M) and PGP-1 (0.5. mu.g/mL) were added to each solution, followed by reaction at 37 ℃ for 30 minutes (. lamda. ex/em. 408/513 nm).
(2) Temperature stability: probe BH1 (15. mu.M) was reacted with PGP-1 (0.5. mu.g/mL) in an enzyme buffer solution at various temperatures (25 ℃, 30 ℃, 35 ℃, 37.5 ℃, 40 ℃, 45 ℃) for 30 minutes (. lamda.ex/em. 408/513 nm).
3.2.5 enzyme kinetic parameter testing
The enzyme assay buffer was used to prepare BH1 at concentrations of 0, 1, 2, 5, 10, 20, 50 μ M, and 50 μ L was pipetted into 384 well plates. To the solution, 50. mu.L of GGT solution (final concentration: 25U/L) was immediately added, and the resulting mixture was placed in a microplate reader, and the fluorescence value was measured every 10 minutes at 37 ℃ (λ ex/em ═ 360nm/500nm) for 2 hours. Using the Michaelis-Menten formula:
V0＝Vmax([S])/(km+[S])
wherein k ismThe value is known as the Michaelis constant, VmaxIs the reaction rate when the enzyme is saturated with the substrate, [ S ]]Is the substrate concentration.
3.2.6 determination of Quantum yield
Using the reference method, coumarin307 (coumarins 307) was selected as the standard substance with a quantum yield of 0.56 in ethanol solution using the formula: phis＝Φr(Arηs 2Ds/Asηr 2Dr) And calculating to obtain the quantum yield. Wherein phirAs quantum yield of the standard substance, ArIs the absorbance of the standard substance and the analyte, DrAnd DsIs the fluorescence integral area, eta, of the standard substance and the analyterAnd ηsThe refractive indexes of the standard substance and the solution of the substance to be detected are shown. r and s represent the standard substance and the analyte, respectively.
3.2.7 measurement of two-photon absorption Cross section
First, the two-photon fluorescence emission intensity of BH1 and TPAN (10mM PBS, 5% DMSO, pH 7.42) under 690-820nm excitation in the 400-600nm range was measured. The TPE fluorescence emission intensity of a reference substance Flu1 with the same excitation wavelength is measured at the same time, and the two-photon property is reported. The two-photon absorption cross section (δ) is calculated using the following formula:
δ＝δref(ΦrefcrefηrefF)/(ΦcηFref)
wherein ref represents a reference molecule, σ is a two-photon absorption cross-section, c is the concentration of the sample, η is the refractive index of the solution, F is the integrated area of the sample, Φ is the fluorescence quantum yield, σ is the fluorescence quantum yieldrefIs the two-photon absorption cross section of the reference.
3.2.8 cell culture
Human derived tumor cells Thp1, human derived hepatoma cells HepG-2, human brain neuroma cells SH-SY5Y and mouse monocyte macrophage leukemia cells RAW264.7 were cultured in Dulbecco's Modified Eagle Medium (DMEM) containing 10% Fetal Bovine Serum (FBS), 1% streptomycin and penicillin, and placed at 37 ℃ in the presence of 5% CO2In an incubator.
3.3.9 cell imaging experiment
The cells were seeded in30 mm glass-bottom dishes and when the cell confluence reached 60-70%, the cell culture medium was replaced with fresh medium containing 10. mu.M TPAN-Glu and 1% DMSO and incubated in an incubator for various times (0-60 min) while the cells without TPAN-Glu were used as a control. The inhibitor group was preincubated for 30 minutes with the appropriate concentration of inhibitor, the medium was removed, and the cells were washed 3 times with pre-warmed DMEM, followed by incubation with the medium containing BH 1. Prior to imaging, the medium containing probe BH1 was aspirated, washed 3 times with pre-warmed DMEM, and 1mL of fresh medium was added again for cell imaging.
Cell imaging conditions: single photon excitation light λ ex 405nm, emission light λ em reception band: 450-550 nm; two-photon excitation light λ ex is 760nm, emission light λ em reception band: 450-550 nm. Unless otherwise indicated, data are presented as mean ± Standard Deviation (SD) of three independent measurements.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be construed as the protection scope of the present invention.