172 results about "Phage display" patented technology

The invention relates to a nano antibody targeting cadherin 17 and application thereof, and relates to the technical field of immunology and molecular biology, the amino acid sequence of a complementary determining region of the nano antibody targeting cadherin 17 comprises CDR1 shown as any one of SEQ ID NO: 21-32, CDR2 shown as any one of SEQ ID NO: 34-45, and CDR3 shown as any one of SEQ ID NO: 47-58. According to the invention, an alpaca immune phage display library is constructed, a series of nano antibody molecules targeting cadherin 17 (CDH17) are screened from the alpaca immune phage display library, and functions and applications of the nano antibody are verified at various levels of CDH17 antigen protein, CDH17 target cells, CDH17 CAR-T cells and the like.

The invention belongs to the field of molecular biology and immunology, and particularly relates to an anti-CD3 nano antibody capable of activating the activity of T cells as well as a preparation method and application of the anti-CD3 nano antibody. The invention provides a preparation method of the anti-CD3 nano antibody. The preparation method comprises the following steps: constructing a CD3 plasmid and an overexpression cell line, and immunizing alpaca to obtain peripheral blood mononuclear cells (PBMC) of the alpaca; extracting RNA (Ribonucleic Acid) and carrying out reverse transcription to obtain cDNA; carrying out PCR amplification on the antibody gene segment and cloning the antibody gene segment to a phage display vector; and electrically transforming the vector into SS320 competent cells to obtain the nano antibody library. After two rounds of panning, detecting and screening an antibody clone capable of being combined with the CD3 protein through ELISA (Enzyme-Linked Immunosorbent Assay); an antibody sequence is selected through sequencing, and an antibody protein is expressed by using a mammalian cell high-throughput expression system; and then detecting and screening the antibody which is only specifically combined with the CD3. The method disclosed by the invention is simple, convenient and rapid to operate, and can be used for preparing active antibodies for treating potential tumors and proliferative diseases.

The invention belongs to the technical field of food and feed analysis and detection, and particularly provides a nano antibody for detecting bacitracin methylene salicylate, and the nano antibody comprises a nano antibody BMD-BA19 and a nano antibody BMD-CA45; the amino acid sequence of a VHH chain of the nano antibody BMD-BA19 is as shown in SEQ ID NO: 1, and the amino acid sequence of a VHH chain of the nano antibody BMD-CA45 is as shown in SEQ ID NO: 2. The bacitracin methylene salicylate serves as a research object, after the bacitracin methylene salicylate is coupled with protein, an alpaca is immunized, two nano antibodies resisting bacitracin methylene salicylate are obtained through screening with a phage display technology, and a material is provided for establishing a bacitracin methylene salicylate detection method.

The invention discloses a nano antibody targeting GPRC5D as well as a preparation method and application thereof, and belongs to the technical field of biological medicines. The nano antibody is generated by mixed immunization of a GPRC5D polypeptide antigen with a sequence shown as SEQ ID NO: 1 and a GPRC5D protein antigen with a sequence shown as SEQ ID NO: 2. The preparation method comprises the following steps: mixing the GPRC5D polypeptide antigen and the GPRC5D protein antigen to immunize alpaca, sampling blood, constructing an antibody library, screening a phage display antibody library, expressing protein, and selecting the nano antibody with the highest affinity. The invention further provides a radionuclide labeled molecular probe, the nano antibody is small in molecular weight and can recognize a large number of epitopes, and the molecular probe prepared from the nano antibody can obtain high-quality images, is used for preparing products for developing multiple myeloma or detecting GPRC5D expression level and has wide application prospects.

The present invention relates to the technical field of molecular biology, and in particular, to an anti-CD40 nanobody, and a preparation method therefor and use thereof. The anti-CD40 nanobody provided by the present invention has three unique complementarity determining regions, namely CDR1, CDR2, and CDR3. The present invention further provides a sequence encoding the nanobody or its VHH chain, a corresponding expression vector, and a host cell capable of expressing the nanobody. The present invention includes immunizing an alpaca by constructing a CD40 antigen to obtain a PBMC of the alpaca and constructing a vector; screening an anti-CD40 antibody through phage display; and finally obtaining a highly sensitive and specifically binding antibody through functional assays and sequencing result analysis. The nanobody provided by the present invention can specifically recognize and bind to CD40.

The present invention relates to the field of biotechnology. Specifically, the present invention provides a monoclonal antibody, preparation method, and application of tyrosine iodinated EGFR protein. The present invention prepares tyrosine iodinated EGFR protein antigen peptides, immunizes mice to prepare monoclonal antibodies, and utilizes phage display technology to select and express relevant antibodies using expression vectors. ELISA screening and immunohistochemistry and cell fluorescence detection yield two highly sensitive and specific monoclonal antibodies, M018 and M025. The monoclonal antibodies obtained by screening can be used for the detection and monitoring of tyrosine iodinated modification at position 845 of the EGFR protein, providing support for tumor diagnosis and the development of anti-tumor drugs.

The invention discloses a nano antibody for resisting a listeria monocytogenes MurA protein and application of the nano antibody, and relates to the technical field of biology. The amino acid sequence of the nano antibody is as shown in SEQ ID NO.3. MurA protein of prokaryotically expressed listeria monocytogenes is used as an immunogen to immunize alpaca, total RNA of peripheral blood lymphocytes is extracted, VHH fragments are amplified through reverse transcription and two rounds of nested PCR, the VHH fragments and a pComb3Xss vector are converted into TG1 competent cells after enzyme digestion and connection, and a phage display technology is used for three rounds of elutriation, so that the total RNA of the listeria monocytogenes is obtained. The nanometer antibody for resisting the listeria monocytogenes MurA protein is successfully screened out. The nano antibody can specifically recognize MurA protein and whole listeria monocytogenes, and the immunocolorimetric sensor based on thiolated bacteriophage induced colloidal gold aggregation, which is established by utilizing the nano antibody, is strong in specificity, high in sensitivity and low in detection limit, and can greatly shorten the detection time.

The invention discloses a preparation method and application of a cat main allergen FEL-1 nano antibody FEL-1-Nb, and relates to the technical field of antibody preparation, and the preparation method comprises the following steps: preparing an immunogen; animal immunization and library construction; constructing and panning a phage display library; screening and identifying positive clone; and expression and purification of the nano antibody: cloning the positively cloned VHH gene to an expression vector such as a pET series, transforming an expression strain such as escherichia coli BL21 (DE3), carrying out IPTG induced expression, and purifying through an inclusion body purification method to obtain a high-purity nano antibody protein. The nano antibody FEL-1-Nb provided by the invention can be specifically bound with a cat main allergen FEL-1 protein, the unique amino acid sequence of the nano antibody FEL-1-Nb is shown as SEQIDNO: 1, high-affinity binding with the FEL-1 protein is ensured, the positive clone binding rate is high through phage display panning and ELISA verification, the phage recovery rate after the third round of panning is increased by more than 1000 times compared with the first round of panning, and the positive clone binding rate is higher than that of the first round of panning. Therefore, the nano antibody has excellent targeted recognition capability.

The invention discloses a pig whole sperm membrane protein antigen specific nano antibody library construction method which comprises the following steps: S1, immunizing alpaca with pig whole sperms, and separating peripheral blood cells after immunization; s2, RNA in peripheral blood cells is extracted, cDNA is obtained through reverse transcription, and a VHH coding sequence of an antibody is amplified; s3, cloning the amplified VHH coding sequence to a bacteriophage plasmid vector to prepare a recombinant bacteriophage vector; s4, transforming the recombinant bacteriophage vector into escherichia coli and carrying out enlarged culture to obtain a bacteriophage display library; and S5, performing panning on the phage display library for a plurality of times by using the pig X / Y sperms, and constructing the pig single sex sperm specific nano antibody library. According to the method, the pig whole sperm is adopted as an immunogen for immunizing alpaca for the first time, the capacity of the constructed antibody library reaches 3.4 * 10 < 8 > pfu, the abundance of the antibody library is higher, the coverage degree of whole sperm antigens is higher, and the variety is more complete, so that the capture success rate of the pig sex control specific antibody is increased, and a foundation is laid for industrial application of the pig sperm specific antibody.

The invention discloses a stem cell composition and application thereof in regulating sub-health. The stem cell composition comprises mesenchymal stem cells (MSCs) modified by fusion polypeptide and an anti-IL-6R single domain antibody. The amino acid sequence of the fusion polypeptide is as shown in SEQ ID NO.1, and the fusion polypeptide is modified on the surface of stem cells through click chemistry, so that the chemotactic migration ability, collagen matrix affinity and inflammation tolerance of the stem cells are remarkably improved. The anti-IL-6R single-domain antibody is obtained through phage display screening, the VHH gene of the anti-IL-6R single-domain antibody is shown as SEQ ID NO.2, and the anti-IL-6R single-domain antibody has high affinity and activity of inhibiting an IL-6 / STAT3 signal channel. Animal experiments show that the composition can significantly reduce inflammatory factor (IL-6) and cortisol levels of chronic stress model mice, improve oxidation resistance (SOD) and recover immune homeostasis, and provides an innovative treatment strategy for adjustment of sub-health status.

This invention discloses a polypeptide that specifically binds to the coronavirus S protein, its encoding gene, and its applications, belonging to the field of molecular biology. The polypeptide specifically binding to the coronavirus S protein provided by this invention contains the following amino acid sequence: HFVKTPARWAWG, obtained through screening using phage display technology. The polypeptide provided by this invention can specifically bind to the coronavirus S protein and specifically block the binding of the coronavirus S protein to ACE2, thereby inhibiting coronavirus infection and can be used to prepare anti-coronavirus drugs.

The utility model provides a pipetting device and a phage display device with the pipetting device, and the pipetting device comprises a first pipetting needle, a second pipetting needle, a first delivery pump, a second delivery pump and a flow path switching valve, the flow path switching valve is provided with a small-flow pipetting flow path and a large-flow pipetting flow path, the small-flow pipetting flow path is communicated with the first delivery pump and the first pipetting needle, the large-flow pipetting flow path is communicated with the second delivery pump, the first pipetting needle and the second pipetting needle, and the flow path switching valve can be controlled to be switched between the small-flow pipetting flow path and the large-flow pipetting flow path; the pumping flow of the second conveying pump is larger than that of the first conveying pump. According to the utility model, a small-flow pipetting flow path can be selected according to corresponding process requirements to ensure accurate pipetting of liquids such as reagents and sample liquids, and a large-flow pipetting flow path can be selected to ensure high-efficiency transfer of the liquids such as the reagents and the sample liquids, so that the operation efficiency is improved.

This invention provides a peanut allergen peptide, its screening method, and its application. Phage display technology is used to screen for conformational epitopes of Ara h5 and Ara h8 proteins. Polyclonal IgE and IgG antibodies against the target proteins are prepared by immunizing BALB / c mice with Ara h5 and Ara h8 proteins as antigens. ELISA and dotted immunoblotting detection revealed that the titers of polyclonal IgG and IgE against Ara h5 and Ara h8 proteins were 1:64000 and 1:320, respectively, and the antibodies exhibited specificity. Using the antibodies as targets, phage display technology screened the conformational epitope sequences of Ara h5 protein as WETIYSR and FHWWYLK. The conformational epitopes of Ara h8 protein were FPYMKFV, FPYMKFR, SMFARID, and SFHWWLF.

The present invention belongs to the technical field of protein short peptides, and discloses a short peptide specifically binding to a cytokeratin 19 fragment and its use. The cytokeratin 19 fragment is a recognized tumor marker with high specificity and sensitivity, and plays an important role in the early diagnosis, efficacy monitoring and prognosis judgment of non-small cell lung cancer. The present invention relates to a method for obtaining a cytokeratin 19 fragment short peptide Y10 by phage display technology. The amino acid sequence of the short peptide Y10 is shown in SEQ ID NO.1. The specific short peptide screened by the present invention has the characteristics of small relative molecular mass and high affinity, so that a probe can be designed for detecting the cytokeratin 19 fragment, which provides a new direction for the early diagnosis of tumors and the research and development of targeted drugs in clinical practice.

The invention relates to the technical field of biology, and aims to provide an M13 recombinant bacteriophage with PRRSV broad-spectrum neutralizing activity for displaying NPC and application of the M13 recombinant bacteriophage. A nano antibody-CD163 peptide fragment conjugate NPC shown as SEQ ID NO: 1 is displayed on the surface of the N end of capsid protein III of the M13 recombinant phage, 1-3 NPC molecules are contained on the surface of each phage particle, and the phage is used for neutralizing PRRSV (Porcine Reproductive and Respiratory Syndrome Virus). The recombinant bacteriophage provided by the invention is easy to prepare, extremely high in virus titer and excellent in thermal and pH stability; in Marc-145 and PAMs cells, the compound shows strong neutralizing activity on PRRSV II type 1, 3, 5 and 8 pedigree, so that the compound has broad-spectrum neutralizing capacity; the compound can be used as a PRRSV prevention and control preparation, and a new thought is provided for development of safe and efficient novel antiviral drugs or biological preparations.

The invention belongs to the technical field of tumor immunotherapy, and relates to an anti-Claudin18.2 single-domain antibody, a multifunctional fusion protein, a recombinant natural killer cell (CT-CAR-NK), and preparation and application thereof. Through alpaca immunization and phage display library construction and panning, the single-domain antibody VHH-C18.2-1 specifically combined with Claudin18.2 is obtained, and the amino acid sequence of the single-domain antibody VHH-C18.2-1 is SEQ ID NO: 1. The amino acid sequence of the designed fusion protein is SEQ ID NO: 3, the fusion protein sequentially comprises a VHH-C18.2-1, a flexible Linker, a TGF-beta RII extracellular domain, a CD8alpha hinge region, a CD8alpha transmembrane region, a 4-1BB intracellular domain and a CD3zeta intracellular domain from the N end to the C end, and the fusion protein has the functions of targeting, resisting TGF-beta inhibition and activating signals. The fusion protein gene transfects human peripheral blood CD56 + CD3-NK cells through lentivirus to obtain CT-CAR-NK, in-vitro verification shows that the CT-CAR-NK still keeps efficient killing in an immunosuppression environment, tumor growth can be remarkably inhibited in vivo, the lifetime can be prolonged, and a safe and efficient scheme is provided for Claudin18.2 positive solid tumor treatment.

The invention relates to a fully humanized single-domain antibody for resisting Glypican-3 and an application of the fully humanized single-domain antibody. The antibody comprises three heavy chain complementary determining regions (CDRs), and the amino acid sequence of the CDRs is the 31st-35th amino acid sequence of SEQ ID NO: 1; the amino acid sequence of the CDR2 is the 50th-66th amino acid sequence of SEQ ID NO: 1; the amino acid sequence of the CDR3 is the 99-107th amino acid sequence of SEQ ID NO: 1. According to the invention, a bacteriophage display technology is utilized, antibody screening is carried out through targeting human GPC3 protein, and one anti-human GPC3 specific fully-humanized monoclonal single-domain antibody is obtained; the antibody can be specifically combined with human GPC3, can effectively inhibit activation of a Wnt signal, provides an effective alternative antibody drug for HCC treatment with GPC3 as a target, and has a potential clinical application prospect.

The invention belongs to the technical field of in-vitro diagnosis, and particularly relates to an anti-mycoplasma pneumoniae antibody, a mycoplasma pneumoniae detection quality control product and a preparation method and application of the mycoplasma pneumoniae antibody and the mycoplasma pneumoniae detection quality control product. The invention provides an anti-mycoplasma pneumoniae antibody which comprises a light chain variable region and a heavy chain variable region, and the light chain variable region and the heavy chain variable region are specifically combined with a C-terminal immunodominance region of mycoplasma pneumoniae P1 protein. Wherein the C-terminal repeat region of the mycoplasma pneumoniae P1 protein is a core immunogenicity region, has high conservative property and strong immunogenicity, can induce a host to generate a specific IgM antibody in the early stage of infection, and is an ideal antibody target. The anti-mycoplasma pneumoniae antibody is obtained by screening through a phage display technology, has high affinity and high specificity, can effectively recognize the C-terminal immunodominance region of the mycoplasma pneumoniae P1 protein, and provides a reliable detection tool for early diagnosis of mycoplasma pneumoniae.

The invention relates to the technical field of medical supplies, and discloses an orally disintegrating film for promoting remineralization of enamel and a preparation method thereof.The orally disintegrating film takes hydroxypropyl methyl cellulose, microcrystalline cellulose, starch and the like as film base materials and has the advantages of being thin, light, good in flexibility, free of toxicity and stimulation, good in biocompatibility and biodegradability and the like; and the composition can be quickly dissolved in the oral cavity to take effect. The device has the advantages of quick effect, convenience in carrying, easiness in use and the like. The orally disintegrating film serves as a direct carrier of an inducer for inducing remineralization of enamel, so that the orally disintegrating film becomes a more effective transmission system. A bacteriophage display technology is utilized, a peptide fragment with strong adsorption capacity with HAP is integrated into a carrier bacteriophage DNA, and purification is performed after large-scale amplification, so that the peptide fragment is used as an important effective component of the orally disintegrating film.

The invention belongs to the technical field of biological pharmacy, and particularly discloses a Siglec-15 affinity peptide and application thereof. According to the invention, a phage display heptapeptide library high-throughput screening technology is adopted, Siglec-15 affinity peptide 7-8 is obtained through multiple rounds of screening, and the Siglec-15 affinity peptide 7-8 is optimized and modified to obtain a reversed sequence flip peptide d-7-8. Experimental results show that the Siglec-15 affinity peptide can be used for affinity of Siglec-15 protein and blocking the interaction between Siglec-15 and a ligand Sialyl-Tn of Siglec-15, so that the anti-tumor effect is achieved; an in-vitro cell level experiment shows that the Siglec-15 affinity peptide has a relieving effect on inhibition of Siglec-15 on CD8 + T cell proliferation, has an obvious immune activation effect, does not have obvious toxic or side effects, can be used for preparing an anti-tumor drug or a detection reagent taking Siglec-15 as a target spot, and has a relatively good medical application prospect.

The present application relates to a kind of artificially synthesized recombinant monoclonal antibody with human antibody amino acid sequence as framework.The present application uses phage display technology, and obtains one monoclonal antibody H11 from Tomlinson I+J phage library, and these new amino acid sequences constitute CDR1, CDR2 and CDR3 region, can be combined with A29L protein specific binding.It shows good stability, high specificity and high affinity and other characteristics, provide tool support for subsequent monkeypox virus diagnosis and detection with A29L protein as target.

The invention discloses a cat parvovirus VP2 protein nano antibody as well as a preparation method and application thereof, and belongs to the technical field of biological medicines. The amino acid sequence of the cat parvovirus VP2 protein nano antibody is as shown in SEQ ID NO. 1 or SEQ ID NO. 2. According to the invention, an alpaca is immunized by using FPV VP2 protein, a phage display nano antibody library is constructed, and two nano antibodies 3D6 and 1B9 with strong specificity and high affinity are obtained through multiple rounds of panning and identification. Through identification, the nano antibodies 3D6 and 1B9 can be specifically combined with FPV and VP2 proteins, and have high affinity and remarkable virus neutralizing activity. The nano antibody can be used for preparing a detection reagent or kit for feline parvovirus infection, and rapid and accurate diagnosis is realized; the compound can also be used as an active component to prepare a therapeutic drug, and provides a special therapeutic scheme for FPV infection. The nano antibody provides an important material basis for developing a novel diagnostic tool and a specific therapeutic drug aiming at the feline parvovirus.

This invention discloses nanobodies against rabies virus G protein and their applications, belonging to the field of nanobody technology. The nanobodies are antibody 11G6, antibody 9F7, or antibody 9A3; the amino acid sequence of antibody 11G6 is shown in SEQ ID NO. 8; the amino acid sequence of antibody 9F7 is shown in SEQ ID NO. 13; and the amino acid sequence of antibody 9A3 is shown in SEQ ID NO. 18. This invention uses phage display technology to screen for nanobodies with high affinity and high neutralizing activity. Based on this, this invention utilizes the advantage of the small size of nanobodies and verifies their unique ability to cross the blood-brain barrier (BBB) ​​through Transwell experiments, overcoming the limitation that large molecules such as antibodies and drugs cannot cross the BBB to enter the brain. This invention provides a new drug option for the treatment of rabies virus and has significant clinical implications.

The application belongs to the technical field of biology and particularly relates to a nano antibody against African swine fever virus K205R protein and application. The application provides a nano antibody KR-6 against African swine fever virus K205R protein, wherein the nano antibody KR-6 is obtained through construction and screening of a phage display nano antibody library, is a heavy chain antibody variable region fragment, and has an amino acid sequence shown in SEQ ID NO. 1. The nano antibody has high affinity to African swine fever virus K205R protein and African swine fever virus, can specifically recognize African swine fever virus, and can be used for diagnosis, prevention or treatment of African swine fever.

There is an interest to develop anti-ROBO4 antibodies that can be suitable for the treatment of cancer. The inventors produced new human antibodies directed against ROBO4 were by a phage display strategy and the antibody selection was performed by using HEK and HEK stably expressing ROBO4 (HEK-ROBO4) cell lines. As a first step, a batch of 6 different antibodies named D3, H3, H9, E11, H11 and G12 was tested for their binding properties. The antibodies were then tested for their ability to inhibit the attachment of tumor cells to osteoblastic cells in monolayers. Finally the inventors showed that the anti-ROBO4 antibodies E11 and G12 inhibits significantly the formation of the tumor spheroid. The present invention thus relates to anti-ROBO4 human monoclonal antibodies and uses thereof for the treatment of cancer.

A plurality of anti-UPAR single-domain antibodies are obtained by means of phage display library screening technology. The anti-UPAR single-domain antibody can efficiently bind to UPAR, and has application prospects in the treatment of related diseases.

The invention discloses a screening method and application of a shark-derived anti-idiotypic nano antibody, and belongs to the technical field of biological pharmacy and vaccines. The screening method comprises the following steps: immunizing adult shark by using a target pathogen specific antigen, collecting peripheral blood, separating lymphocytes, extracting RNA (Ribonucleic Acid), carrying out reverse transcription to synthesize cDNA (Complementary Deoxyribonucleic Acid), amplifying a nano antibody variable region fragment of a shark IgNAR (Immunoglobulin Nucleic Acid Receptor) gene, and constructing a phage display gene bank of which the storage capacity is greater than or equal to 1 * 10 < 8 > CFU and the recombination rate is greater than or equal to 85%; a variable region of a target pathogen specific antibody is taken as a target, specific bacteriophage is enriched through 3-4 rounds of gradient washing and elutriation (Tween-20 concentration and washing time are gradually improved), and the shark source anti-idiotypic nano antibody with high affinity and high purity (greater than or equal to 95%) is obtained by combining ELISA screening positive clone, gene sequencing de-weighting and SPR detection (combining dissociation constant KDlt, 1 * 10 <-7 > mol / L).

The present invention discloses a monoclonal antibody H2 that specifically binds to the lung cancer marker CYFRA21-1 and its application, relating to the field of biomedicine technology. First, using phage display technology, a lung cancer marker CYFRA21-1 monoclonal antibody H2 is obtained by panning from the Tomlinson I+J phage library. The antibody has a heavy chain complementary determining region and a light chain complementary determining region composed of novel amino acid sequences, and can specifically bind to the CYFRA21-1 protein. The binding has the characteristics of high affinity, high specificity and stability. The monoclonal antibody H2 for the lung cancer marker CYFRA21-1 of the present invention can not only efficiently and accurately detect the concentration of CYFRA21-1 protein, but also can be used for immunostaining of lung cancer tumor cells and lung cancer tissues in pathological diagnosis, which is of great significance for detecting the concentration of CYFRA21-1.

The present invention relates to the technical field of molecular biology, and in particular, to an anti-CD40 nanobody, and a preparation method therefor and use thereof. The anti-CD40 nanobody provided by the present invention has three unique complementarity determining regions, namely CDR1, CDR2, and CDR3. The present invention further provides a sequence encoding the nanobody or its VHH chain, a corresponding expression vector, and a host cell capable of expressing the nanobody. The present invention includes immunizing an alpaca by constructing a CD40 antigen to obtain a PBMC of the alpaca and constructing a vector; screening an anti-CD40 antibody through phage display; and finally obtaining a highly sensitive and specifically binding antibody through functional assays and sequencing result analysis. The nanobody provided by the present invention can specifically recognize and bind to CD40.

The present invention relates to an anti-CD28 nano antibody, a method for screening CD28 nano antibodies based on a natural library and an application thereof, and belongs to the field of biotechnology. The anti-CD28 nano antibody of the present invention is composed of a heavy chain, and the heavy chain includes three complementary determining regions, namely CDR1, CDR2 and CDR3; the amino acid sequence of the CDR1 is shown in SEQ ID NO:3; the amino acid sequence of the CDR2 is shown in SEQ ID NO:4; the amino acid sequence of the CDR3 is shown in SEQ ID NO:5. The present invention obtains a nano antibody targeting CD28 through an alpaca nano antibody natural library and phage display technology, which can specifically recognize CD28 and has application prospects for the preparation of tumor therapeutic drugs and tumor detection.