37 results about "Dextran sulphate" patented technology

The invention discloses a method for detecting the residual quantity of dextran sulfate sodium in an antibody. Specifically, the invention provides a method for detecting the residual quantity of dextran sulfate sodium in an antibody, which comprises the following steps: removing protein in the antibody, and reacting with a 2-aminopyridine solution; a high performance liquid chromatography method is adopted to detect a test sample and sodium dextran sulfate standard substances with different concentrations. The detection method disclosed by the invention is low in detection limit, high in accuracy and suitable for analyzing the residual quantity of dextran sulfate in the antibody.

The invention discloses an inflammatory bowel disease model, a construction method and application thereof and a drug evaluation method based on the inflammatory bowel disease model, and belongs to the technical field of inflammatory bowel disease model construction. A highly bionic intestinal crypt-villus three-dimensional structure is formed based on self-organization of an intestinal cell line C2BBe1, the intestinal crypt-villus three-dimensional structure and a DMEM complete medium containing dextran sulfate sodium are added into an upper chamber of a double-layer culture chamber Transwell, the DMEM complete medium is added into a lower chamber of the double-layer culture chamber Transwell, culture is performed for 2 days, and the inflammatory bowel disease model is obtained. The method takes effect quickly and is highly simulated, the obtained model can simulate the space-time dynamic development process of intestinal inflammation molecular characteristics, and the natural recovery model and the drug treatment model constructed based on the model can provide a brand new platform for researching an inflammation regression mechanism and a drug intervention effect.

The invention relates to the technical field of pharmaceutical preparations, in particular to a florfenicol preparation with high water solubility and antibacterial effect and a preparation method of the florfenicol preparation. The florfenicol preparation with high water solubility and antibacterial effect is prepared from the following raw materials in parts by mass: 20 to 30 parts of florfenicol, 30 to 50 parts of beta-cyclodextrin, 30 to 50 parts of solid polyethylene glycol, 2 to 5 parts of lauryl sodium sulfate, 100 to 200 parts of dopamine aqueous solution and 1 to 5 parts of dextran sulfate aqueous solution. Wherein the concentration of the dopamine aqueous solution is 1-3 g / L, and the concentration of the dextran sulfate aqueous solution is 0.1-0.5 mol / L. The preparation method is relatively wide in application, is commonly used for granulating heat-sensitive materials and medicines which are easy to decompose when encountering water, and is convenient for subsequent re-tabletting or encapsulation; and compared with wet granulation, the method has the advantages of simple process, low energy consumption, low filler consumption and the like.

This invention relates to an absorbable, slow-release regulator for off-season antler growth in sika deer and red deer, and its preparation method, belonging to the field of off-season antler growth regulators. The regulator comprises 330 mg–360 mg medroxyprogesterone acetate (MPA), 50 mg–55 mg dextran sulfate (DS), and 200 mg–220 mg sodium hyaluronate (HA), diluted with water for injection to a final volume of 1.0 mL. The molecular weight of medroxyprogesterone acetate (MPA) is 386.52 kDa; the molecular weight of dextran sulfate (DS) is 36–50 kDa; and the molecular weight of sodium hyaluronate (HA) is 20–400 kDa. This invention utilizes exogenous progesterone to induce off-season antler growth in male deer through hormonal regulation. The use of absorbable materials is environmentally friendly and harmless to the body, allowing for natural absorption and normal excretion through the body's metabolic processes. A single injection is sufficient to provide efficacy for over 35 days. Using progesterone to regulate off-season antler growth is low-cost and has a high success rate.

This invention belongs to the field of vertebrate technology, specifically relating to a method for constructing a complex inflammatory animal model in middle-aged and elderly individuals and its related applications. The method includes: selecting adult animals for adaptive feeding, daily subcutaneous injection of D-galactose to establish a susceptibility to aging and oxidative stress, and administering sodium dextran sulfate (DSS) solution within a specific time window to induce intestinal inflammation, forming a complex inflammatory state through gut-hepatic axis interactions. The constructed animal model simultaneously exhibits intestinal inflammatory damage, abnormal hepatic oxidative stress, and aging-related characteristics, realistically simulating the pathological process of gut-hepatic axis dysfunction in middle-aged and elderly individuals. This model is suitable for screening and evaluating drugs, medical nutrition products, and functional foods that improve gut-hepatic axis dysfunction, providing a reliable technical platform for research on related disease mechanisms and the development of interventional substances.

The invention discloses a drug delivery system containing loaded adriamycin as well as a preparation method and application of the drug delivery system. The drug delivery system comprises poly (beta-amino ester) coupled with adriamycin, wherein the surface of the poly (beta-amino ester) is coated with dextran sulfate, and the poly (beta-amino ester) takes a fourth-generation lysine dendritic molecule Lys-G4 as a core. The drug delivery system has a pH-dependent drug release characteristic, has remarkable toxicity to C6 and U87MG glioma cells, has the capabilities of inducing apoptosis, inhibiting migration and targeting subcellular localization, and can effectively penetrate through a blood-brain barrier model and 3D tumor spheres. The delivery system is compounded with PLA-PEG-PLA thermosensitive hydrogel, and the thermosensitive hydrogel with a drug storage function is successfully constructed. Good tumor inhibition effect and biocompatibility are shown in nude mouse subcutaneous and in-situ glioma models. The invention not only provides a new strategy for overcoming the blood brain barrier, but also can effectively reduce the systemic toxicity, and opens up a new research thought and method for glioma treatment.

The invention belongs to the technical field of biology, and particularly relates to a bacteriostatic agent and a preparation method and application thereof. Comprising the following steps that antibacterial peptide modified silver nanoparticles are prepared, specifically, antibacterial peptide and silver nitrate grow in situ under the action of a reducing agent, and the antibacterial peptide modified silver nanoparticles are obtained; preparing a bacteriostatic agent: dissolving the antibacterial peptide modified silver nanoparticles by using a cross-linked substance of chitosan and dextran sulfate to obtain the bacteriostatic agent; the charge of the cross-linked substance of the chitosan and the dextran sulfate is 0. Through mutual attraction of positive charges of the antibacterial peptide and negative charges of the silver nanoparticles, the silver nanoparticles wrapped by the antibacterial peptide are formed, the self-assembly or irregular agglomeration behavior of the antibacterial peptide is effectively controlled, a nanometer network formed by crosslinking chitosan with dextran sulfate can stabilize the nanometer form of the silver nanoparticles, and the antibacterial activity of the antibacterial peptide is improved. The core-shell structure formed by the silver nanoparticles wrapped by the antibacterial peptide can be stabilized, the silver nanoparticles wrapped by the antibacterial peptide can also be dispersed, and mutual agglomeration of the core-shell structure is prevented.

The invention discloses kombucha capable of improving ulcerative colitis as well as a preparation method and application of the kombucha, and belongs to the technical field of fermented foods. The preparation method comprises the following steps: S1, inoculating 5% of kombucha pellicle into black tea sugar tea water for fermentation culture, and activating to prepare Kangpu tea fermentation liquor; and S2, inoculating the Kangpu tea fermentation liquor in the S1 into black tea sugar tea water according to the inoculum size of 1%, and performing fermentation culture for 4 days to obtain the kombucha. According to the kombucha capable of improving ulcerative colitis as well as the preparation method and the application of the kombucha, the kombucha can effectively relieve colon injury caused by dextran sulfate sodium (DSS), regulate the intestinal barrier and inflammation level and effectively relieve colon oxidative injury at the same time.

The application relates to the technical field of pharmaceutical preparations, in particular to a florfenicol preparation with high water solubility and bacteriostatic effect and a preparation method thereof.The raw materials of the florfenicol preparation with high water solubility and bacteriostatic effect include, by mass fraction, florfenicol 20-30 parts, beta-cyclodextrin 30-50 parts, solid polyethylene glycol 30-50 parts, sodium dodecyl sulfate 2-5 parts, dopamine aqueous solution 100-200 parts and dextran sulfate aqueous solution 1-5 parts; wherein the concentration of the dopamine aqueous solution is 1-3 g / L, and the concentration of the dextran sulfate aqueous solution is 0.1-0.5 mol / L.The application has a wide application range, is commonly used for granulation of heat-sensitive materials and drugs which are easily decomposed in water, and is convenient for subsequent re-compression tabletting or encapsulation; and compared with a wet granulation method, the application has the advantages of simple process, low energy consumption, small filler consumption and the like.

Ferrous fumarate, gellan gum and dextran sulfate are prepared into an ion-sensitive tablet, and the surface of the ion-sensitive tablet is subjected to enteric coating, so that the ion-sensitive tablet basically does not release iron elements in the stomach, and the ion-sensitive tablet is quickly converted into iron-containing gel when entering the intestinal tract, so that the iron-containing gel can be quickly dissolved in the intestinal tract. Further, slow and uniform release in intestinal tracts is realized, and stimulation of high-dose iron to gastrointestinal tracts is reduced; in addition, ferrous fumarate and Chinese herbal medicines are combined to form beneficial complementation, so that the dual purposes of supplementing iron and tonifying qi and blood are achieved, and the iron-deficiency anemia is effectively improved.

The invention discloses a high-density lipoprotein cholesterol determination kit and a detection method thereof. The kit comprises a reagent 1 and a reagent 2, the reagent 1 is prepared from a buffer solution, inorganic salt, dextran sulfate, a macromolecular cationic polymer, TOOS, peroxidase, ascorbic acid oxidase and a preservative; the reagent 2 is prepared from a buffer solution, a surfactant 1, 4-aminoantipyrine, cholesterol oxidase, cholesterol esterase and a preservative. The kit has the advantages of being high in accuracy, good in anti-interference performance and the like, automatic detection can be achieved on a full-automatic biochemical analyzer, and compared with a traditional dextran sulfate precipitation method, the content of high-density lipoprotein cholesterol (HDL-C) in a lipid turbid sample can be more accurately detected.

The invention relates to a nanofluid memristor and discloses a nanofluid memristor based on a polyelectrolyte conformation hysteresis effect and a preparation method thereof, the memristor comprises a glass substrate, a multilayer medium nano film layer is deposited in the center of the glass substrate, and the multilayer medium nano film layer is sequentially covered with a flow channel layer and a sealing layer; the flow channel layer comprises two flow channels, and the two flow channels are connected through a multi-layer medium nano-film; the sealing layer is provided with liquid adding ports corresponding to the ports of the flow channels, a polybrene solution and a dextran sulfate solution are added into the two flow channels through the liquid adding ports respectively, and the two solutions make contact with the multilayer medium nano-film layer; the liquid storage pool is connected with the AgCl electrode, voltage is applied to the two ends of the multi-layer medium nano-film layer through the AgCl electrode, and a solution enters or is far away from a nano-channel of the multi-layer medium nano-film layer to generate a memristive effect. The nanofluid memristor disclosed by the invention has the advantages of simple preparation, wide adjustment range, large on / off ratio and strong compatibility.

The invention discloses a tissue sealing reagent, a multi-index RNA-protein co-dyeing method and application, and belongs to the technical field of molecular biology. The tissue sealing reagent comprises the following components: ethylene carbonate, dextran sulfate, sodium chloride, citric acid, trisodium citrate dihydrate and herring sperm DNA (deoxyribonucleic acid). The invention further discloses a multi-index RNA-protein co-dyeing method, multi-index co-dyeing of RNA-protein on the same tissue slice can be achieved, multiple RNA in-situ hybridization strategies are compatible, and an effective solution is provided for the non-specific dyeing problem occurring in the existing hybridization strategies. By optimizing sample treatment, a co-staining method and a signal enhancement strategy, high-resolution spatial localization of gene expression on the tissue slice is achieved, the method is particularly suitable for research of cell distribution and gene expression modes of complex tissues, and important technical support can be provided for research of disease mechanisms, development of targeted therapy and precision medicine.

The present application relates to the technical field of veterinary medicine, and discloses a kind of absorbable sustained-release agent for inhibiting the fighting behavior of male deer during estrus, comprising the following steps: stirring micronized medroxyprogesterone acetate with dextran sulfate and water for injection to obtain a homogeneous suspension paste; adding sodium hyaluronate dry powder without adding solvent to knead, and through competitive water absorption, dextran sulfate is dehydrated to form a physical coating layer on the surface of drug particles, obtaining a non-saturated hard rubber mass; after cooling, the remaining water for injection is pre-cooled and forced to pass through a microporous screen to achieve reciprocating convection extrusion, and then the product is obtained by swelling after standing.The present application utilizes the double retardation effect of interface physical coating layer and three-dimensional network of gel to inhibit the initial drug burst of long-acting preparation, prevent the gravity settlement of drug particles, achieve the long-term stable release of medroxyprogesterone acetate in animal body, and further reduce the fighting behavior of male deer during estrus.

Provided herein are methods of detecting one or more nucleic acids in a biofluid sample. The methods include adding to the biofluid sample a composition comprising a sufficient amount of dextran sulphate to provide between 50 nM and 5 μM dextran sulphate when the composition is added to the biofluid sample.

The invention relates to the technical field of biological medicine, and provides a preparation method and application of a macrophage targeting exosome. The method comprises the following steps: firstly, stimulating stem cells by utilizing N-azide acetyl mannosamine-tetra-acylation (Ac4ManNAz); then, dibenzocyclooctyne-dextran sulfate (DBCO-DS) is adopted to stimulate the pretreated stem cells, and the stem cells are modified; after the stem cells are cultured, the stem cell exosome of the targeted macrophage is obtained through a gradient centrifugation method and an ultra-high-speed centrifugation method. Through verification, the exosome can effectively regulate and control the polarization phenotype of the macrophage to be converted from M1 to M2.

This invention relates to suspended cells, specifically to an anti-suspension cell clumping complex and its preparation method, and its application. The anti-suspension cell clumping complex is characterized by comprising sodium dextran sulfate, sodium heparin, and non-essential amino acids. The complex of this invention can reduce the cell clumping rate after 4 days of large-scale suspended cell culture (7.18%-10.27%). The optimal formulation shows a clumping rate as low as 7.18% (≤10%), significantly superior to sodium dextran sulfate (DSS), sodium heparin, non-essential amino acid groups, and commercially available anti-clumping agents. It effectively solves the problem of cell aggregation and clumping in large-scale, high-density culture of cells adapted to suspension.

The invention provides application of earthworm protein hydrolysate in preparation of an intestinal mucosa barrier protective agent, and belongs to the technical field of earthworm deep processing. The invention provides an application of earthworm protein hydrolysate (EWPH) in preparation of an intestinal mucosa barrier protective agent. EWPH treatment is given to a dextran sulfate sodium salt (DSS)-induced mouse intestinal mucosa injury model, and the effect and the treatment mechanism of the EWPH treatment are evaluated. Results show that the EWPH has a protective effect on intestinal mucosal injury, and the mechanism of the EWPH relates to inhibition of activation of a TLR4-MAPK / NF-kappa B pathway, inhibition of inflammatory cell infiltration, adjustment of inflammatory cytokines and the like. Therefore, the invention proves that the EWPH can be used as an intestinal mucosa barrier protective agent, which also points out a specific promising direction for the production and high-valued processing of EWPH-related bioactive peptides.

The invention discloses nanoparticles loaded with pueraria flower isoflavone as well as a preparation method and application of the nanoparticles, and belongs to the technical field of composite nanoparticles. The nanometer particle loaded with the pueraria flower isoflavone comprises a nanometer particle center and a polysaccharide shell, the centers of the nanoparticles are vinasse prolamin coating pueraria flower isoflavone, and the polysaccharide shells are a dextran sulfate shell and a chitosan shell in sequence from inside to outside. The preparation method comprises the following steps: preparing single-layer nanoparticles loaded with pueraria flower isoflavone by taking sodium carbonate as a sacrificial template; by adjusting the pH value of the solution, the nanoparticles are positively charged, and an electronegative dextran sulfate shell is coated with the electronegative dextran sulfate shell through the electrostatic deposition effect; then mixing with a chitosan solution, and further coating an electropositive chitosan shell to form a layer-by-layer self-assembly structure. The nanometer particles loaded with the pueraria flower isoflavone are higher in release rate in an in-vitro simulated digestion environment and higher in free radical scavenging activity, and a more efficient technology is provided for delivery of the pueraria flower isoflavone.

The invention discloses a double mRNA (messenger Ribonucleic Acid) combined targeted delivery system for treating a lower limb peripheral artery disease (PAD) and application of the double mRNA combined targeted delivery system. The system comprises a microcrystal nanocarbon targeted drug-loading delivery matrix on which messenger ribonucleic acid (mRNA) of an IL-4 gene and / or a VEGF gene is loaded. The matrix comprises matrix microcrystalline nanocarbon, and folic acid (FA), dextran sulfate (DS), polyethyleneimine (PEI) and polyethylene glycol (PEG) which are modified on the surface of the matrix microcrystalline nanocarbon. According to the system, folic acid and dextran sulfate are used for dual targeting of macrophages, so that efficient endocytosis is realized; the mRNA is used for rapidly expressing protein in cytoplasm, so that the risk of genome integration is avoided; through co-delivery of IL-4 and VEGF, functional angiogenesis and tissue repair are synergistically promoted. Preferably, the system can be entrapped in injectable hydrogel to form a gel composite system, so that slow and continuous release of the medicine is realized. The invention further provides a preparation method of the system and application of the system in preparation of drugs for treating ischemic diseases. The system has the advantages of high targeting efficiency, high expression speed, high vascular maturity, lasting effect and the like, and provides a new strategy for PAD treatment.

This invention relates to the field of animal reproductive regulation technology, and discloses a twinning regulator for sika deer males that synchronize estrus and its application method. The regulator is a homogeneous and transparent sol system prepared from trehalose, pituitary follicle-stimulating hormone (FSH), medium- and low molecular weight sodium hyaluronate, low molecular weight dextran sulfate, zinc gluconate, and physiological saline. This invention utilizes sodium hyaluronate of a specific molecular weight and dextran sulfate to construct a polysaccharide sol network, combined with the cross-linking effect of zinc gluconate and the physicochemical stabilizing effect of trehalose, to encapsulate and slowly release FSH. The application method includes implanting and removing a vaginal silicone plug, combined with the injection of pregnant mare serum gonadotropin (PMSG) and the regulator, followed by natural mating. This invention prolongs the half-life of exogenous hormones in the animal, avoids drastic fluctuations in blood drug concentration, and improves the stability of twinning rates in sika deer.

The invention provides a cassiterite collecting agent and a flotation method of sulfur-containing micro-fine particle cassiterite fine silt. The cassiterite collecting agent is formed by mixing benzohydroxamic acid and sodium dextran sulfate. Or the cassiterite collecting agent is a carboxymethyl chitosan-catechol polymer. The combination of a cassiterite collecting agent carboxymethyl chitosan-catechol polymer or benzohydroxamic acid and dextran sulfate sodium has a unique dual-action mechanism of'strong anchoring-bridging flocculation '. Benzohydroxamic acid and dextran sulfate sodium or catechol groups form super-strong coordination with Sn < 4 + > on the cassiterite surface, so that strong anchoring is realized; and a plurality of micro-fine particle cassiterite can be simultaneously adsorbed by a macromolecular long chain to form an easily floated aggregate, so that bridging flocculation is realized. By means of the cassiterite collecting agent, the capturing capacity of 20-micron ultra-fine cassiterite can be remarkably improved. Compared with conventional benzohydroxamic acid, the recovery rate of the micro-fine particle cassiterite is increased by 8-15%, and maximization of resource utilization is achieved.

The present invention aims to provide a composition useful for inhibiting angiogenesis or vascular loss. ru. [Solution] In one embodiment of the present invention, (A) dextran sulfate or a salt thereof, (B) Prepare a composition containing royal jelly extract and (C) bilberry leaf extract. In one embodiment, in the manufacture of an external composition, dextran sulfate or its salt, rh The invention also relates to the use of compositions containing jelly extract and bilberry leaf extract.

The present invention provides Kazachstania unispora KU2, selenium-enriched Kazachstania unispora and their applications, relating to the technical field of functional microbial fermentation. The present invention provides a strain of Kazachstania unispora KU2 with a preservation number of CCTCC NO: M2023410. The Kazachstania unispora provided by the present invention has good selenium enrichment ability, especially high organic selenium enrichment ability. The selenium-enriched Kazachstania unispora provided by the present invention comprises the Kazachstania unispora KU2 and selenium. The selenium-enriched Kazachstania unispora provided by the present invention has a high selenium content and a high organic selenium content, and has a significant alleviating effect on colitis, especially colitis induced by dextran sulfate sodium and / or patulin, providing a reference for the development and mechanism research of anti-colitis drugs; moreover, it can also meet the requirements of organic environmental-friendly foods and feeds.

The invention provides a non-oxygen dependent type photodynamic nano material with a function of targeting M1 macrophages and application of the non-oxygen dependent type photodynamic nano material. The non-oxygen dependent type photodynamic nano material comprises chitosan nano particles coated with porphyrin supramolecules and dextran sulfate sodium salt. The material regulates LSG excessive activation through a neural immune strategy of M1 macrophages in selective apoptosis left stellate ganglion (LSG), so as to prevent and treat malignant arrhythmia after myocardial infarction.

A resin is formed through a ring-opening reaction of dextran sulfate sodium salt and a modified polyether sulfone. The modified polyether sulfone is formed by a reaction of polyether sulfone and an epoxy compound containing a carbon-carbon double bond. The resin may serve as an adsorption material, which can be a porous film or a porous hollow fiber. The adsorption material can be in contact with blood to lower LDL-C concentration in the blood.

The invention discloses application of dextran sulfate sodium in preparation of a medicine for treating and preventing human papilloma virus infection. According to the application, the action effect of the dextran sulfate on inhibiting human papilloma virus type 6, type 16, type 18 and type 58 pseudoviruses from entering 293FT cells is evaluated at the cellular level, and the result shows that the dextran sulfate can effectively inhibit the human papilloma virus type 6, type 16, type 18 and type 58 from infecting the 293FT cells. Results of inhibition of human papilloma virus 16 pseudovirus infection by sodium dextran sulfate according to animal level evaluation show that sodium dextran sulfate can effectively inhibit infection of human papilloma virus 16 pseudovirus on mouse genitals. Sodium dextran sulfate has the advantages of blocking HPV virus from invading cells, preventing virus from expanding infection, being safe, stable, low in cost and the like, and the medicine has the prospect of being developed into a preparation for treating or preventing human papilloma virus infection related diseases.

The invention belongs to the technical field of molecular biological detection, and discloses a reaction system, a kit and a detection method applied to RNA amplification of a complex whole blood sample. The reaction system comprises a buffer component and an enzyme protection component; the buffer component consists of Tris and Bicine and is used for cooperatively maintaining the stability of the pH value of a reaction system in the RNA amplification process of a complex whole blood sample; and the enzyme protection component is composed of AEBSF and dextran sulfate. Through collaborative innovation of a double-buffer system and an active enzyme protective agent, the integrated challenges that the pH is easy to drift, the template compatibility is poor and the enzyme activity is easy to damage when a complex whole blood sample is faced in the prior art are effectively overcome, and a key technical support is provided for rapid, stable and reliable bedside molecular diagnosis.

The invention relates to the technical field of biochemical detection, and discloses a dry chemical test paper for quantitative determination of human whole blood high density lipoprotein cholesterol content, which comprises a diffusion layer, a blood filter layer, a pre-precipitation layer, a precipitation layer, a supplementary precipitation layer and a reaction layer which are sequentially stacked from top to bottom, the pre-precipitation layer is coated with a first reagent, the first reagent contains a precipitant I, the precipitation layer is coated with a second reagent, the second reagent contains a precipitant II, the supplementary precipitation layer is coated with a third reagent, and the third reagent contains a precipitant III; the precipitant I, the precipitant II and the precipitant III respectively adopt at least one of dextran sulfate, polyethylene glycol 2000, phosphotungstic acid and polyethyleneimine, and the precipitant I, the precipitant II and the precipitant III adopt different formulas. The dry chemical test paper can realize simple, rapid, high-precision and high-accuracy quantitative determination of high-density lipoprotein cholesterol in human whole blood, and solves the technical problems of low detection accuracy and precision of existing dry chemical test paper.

The invention discloses a preparation method of a chromatographic purification medium for efficiently separating subunit viruses. Comprising the following steps: (1) preparing a base frame material; (2) adding dextran sulfate sodium salt into the base frame material; (3) adding a phosphate buffer solution, a phase transfer catalyst and a cross-linking agent; (4) reacting under a staged alkaline pH condition, wherein the pH of the second stage is higher than that of the first stage; and (5) after the reaction is finished, washing with alkali liquor and purified water for multiple times to obtain the chromatography purification medium. The molecular weight of the dextran sulfate sodium salt is 25 to 35 kDa, preferably 30 kDa. The base frame material is agarose microspheres, the agarose microspheres are prepared from agarose with the concentration of 3.0%-3.5%, the particle size of the agarose microspheres is 45-165 microns, the mass ratio of the agarose microspheres to the purified water to the dextran sulfate sodium salt is 5: (1-1.5), the phosphate buffer solution is tripotassium phosphate or sodium phosphate, and the concentration of the phosphate buffer solution is 0.005-0.02 mol / L, preferably 0.01 mol / L.