Antimicrocystin-LR nanobodies and their applications

Abstract

This invention belongs to the field of microcystin-LR detection technology, providing anti-microcystin-LR nanobodies and their applications. The anti-microcystin-LR nanobodies have amino acid sequences as shown in SEQ ID NO.1, SEQ ID NO.2, or SEQ ID NO.3. This invention uses phage display technology to screen for nanobodies with high affinity and high specificity for recognizing microcystin-LR, exhibiting advantages such as strong stability and ease of large-scale expression. Various detection tools can be designed based on anti-microcystin-LR, including test strips, immunoassay kits, immunoaffinity columns, biosensor detection chips, or detection probes. This provides novel antibody resources for rapid monitoring of microcystin-LR and lays a material foundation for developing low-cost, high-performance immunoassay technologies, which is of great significance for promoting the monitoring and control of microcystin-LR pollution.

Description

Technical Field

[0001] This invention belongs to the field of microcystin-LR detection technology, and particularly relates to anti-microcystin-LR nanobodies and their applications. Background Technology

[0002] Microcystin-LR (MC-LR) is a cyclic heptacapeptide hepatotoxin produced by cyanobacteria (such as Microcystis). It causes severe damage to organs such as the liver and kidneys by inhibiting the activity of protein phosphatases (such as PP1 and PP2A) and has potential carcinogenicity. In practical applications, the detection of microcystin-LR still faces multiple challenges. Environmental sample matrices are complex, with various components easily interfering with the detection signal and affecting the accuracy of the results. Because the World Health Organization sets strict limits for microcystin-LR in drinking water (≤1.0 μg / L), detection technologies need extremely high sensitivity; however, the stability and reliability of currently used methods are still insufficient. Furthermore, immunoassay-based methods require the use of highly toxic microcystin-LR standards to construct standard curves, which not only increases detection costs but also introduces operational safety hazards and additional management requirements. Antibodies, as key recognition elements, also have limitations in stability and specificity, are easily affected by environmental factors, and may undergo cross-reactions, reducing detection accuracy. While instrumental analytical methods such as chromatography-mass spectrometry (GC-MS) offer high accuracy, they rely on large-scale equipment, specialized operation, and complex sample preparation, making rapid on-site detection and large-scale application difficult. Although some emerging technologies, such as DNA nanostructures and molecularly imprinted sensors, show promise, their anti-interference performance, stability, and cost control in real samples still require further verification. Currently, most of these technologies are still in the laboratory research and development stage and are far from practical application.

[0003] Nanobodies are a class of naturally occurring heavy-chain antibodies derived from camelids, with a molecular weight of approximately 15 kDa, only one-tenth that of traditional antibodies. They exhibit significant advantages in detecting small molecules such as microcystin-LR, pesticide residues, and other biotoxins. These antibodies possess excellent physicochemical stability, tolerating high temperatures, extreme pH environments, and interference from chemical reagents, making them suitable for detecting complex matrix samples, and they have no strict requirements for cold chain transportation and storage conditions. Due to their long CDR3 region structure, nanobodies can penetrate deep into the hidden antigenic epitopes of small molecules, achieving high sensitivity and specificity through high affinity. Furthermore, nanobodies have good water solubility and excellent programmability, and their detection performance can be significantly improved through fusion with reporter enzymes, construction of multivalent forms, or targeted immobilization. They can be produced efficiently and at low cost on a large scale in prokaryotic expression systems, strongly promoting the widespread application of related detection technologies. Most importantly, anti-idiotype substitutes developed based on nanobody technology can mimic toxin antigenic epitopes, thereby avoiding the use of highly toxic standards and providing an innovative solution for the safe and green detection of high-risk small molecules. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides antimicrocystin-LR nanobody and its applications, aiming to solve the problems mentioned in the background art.

[0005] In a first aspect, the present invention provides an antimicrocystin-LR nanobody having an amino acid sequence as shown in SEQ ID NO.1 or SEQ ID NO.2.

[0006] Furthermore, the nucleotide sequence encoding the antimicrocystin-LR nanobody is shown in SEQ ID NO.3 or SEQ ID NO.4.

[0007] Furthermore, the application of antimicrocystin-LR nanobodies in environmental water detection and / or monitoring.

[0008] Furthermore, the antimicrocystin-LR nanobody is used to detect and / or monitor the content of microcystin-LR in environmental water bodies.

[0009] Furthermore, the application of antimicrocystin-LR nanobody in the monitoring of aquatic food and / or water-based food safety.

[0010] Furthermore, the antimicrocystin-LR nanobody is used to detect the residual amount of microcystin-LR in aquatic foods and / or water-based foods.

[0011] Furthermore, the aquatic food includes fish, crustaceans, or shellfish; the water-based food includes drinking water, fruit juice, or carbonated beverages.

[0012] Secondly, the present invention provides a detection tool for antimicrocystin-LR, including antimicrocystin-LR nanobodies.

[0013] Furthermore, the detection tool is any one of the following: test strip, immunoassay kit, immunoaffinity column, biosensor detection chip, or detection probe.

[0014] Thirdly, the present invention provides a photocatalyst for targeted degradation of microcystin-LR, comprising a carrier layer, a photocatalytic active layer and a targeted recognition layer; wherein the targeted recognition layer is an anti-microcystin-LR nanobody.

[0015] The present invention has the following beneficial effects:

[0016] (1) Nanobodies with high affinity and high specificity for recognizing microcystin-LR were screened using phage display technology, exhibiting advantages such as strong stability and ease of large-scale expression. Various detection tools can be designed based on anti-microcystin-LR, including test strips, immunoassay kits, immunoaffinity columns, biosensor detection chips, or detection probes. This provides novel antibody resources for rapid monitoring of microcystin-LR and lays a material foundation for developing low-cost, high-performance immunoassay technologies, which is of great significance for promoting the monitoring and control of microcystin-LR pollution.

[0017] (2) The obtained antimicrocystin-LR is used to detect and / or monitor the content of microcystin-LR in environmental water bodies, to carry out pollution monitoring and early warning, and to provide timely pollution early warning and decision support for environmental management departments; it is also used to detect the residual amount of microcystin-LR in aquatic foods and / or water-based foods, to carry out food safety monitoring, and to protect the health of consumers. Attached Figure Description

[0018] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0019] Figure 1 Phage-ELISA was used to identify and screen antimicrocystin-LR nanobody phages 1-48 in Example 1 of this invention.

[0020] Figure 2 Phage-ELISA was used to identify and screen antimicrocystin-LR nanobody phage 49-96 in Example 1 of this invention;

[0021] Figure 3This refers to phage-ELISA screening of antimicrocystin-LR nanobody phage 97-144 in Example 1 of the present invention;

[0022] Figure 4 The purified antimicrocystin-LR nanobody 119-C4-SBP was identified by SDS-PAGE in Example 2 of this invention.

[0023] Figure 5 The purified antimicrocystin-LR nanobody 20-C4-SBP was identified by SDS-PAGE in Example 2 of this invention.

[0024] Figure 6 The IC50 results of the antimicrocystin-LR nanobodies 20-C4-SBP and 119-C4-SBP in Example 2 of this invention are shown. Detailed Implementation

[0025] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0027] This invention provides an antimicrocystin-LR nanobody having an amino acid sequence as shown in SEQ ID NO.1 or SEQ ID NO.2.

[0028] In some embodiments, the nucleotide sequence encoding the antimicrocystin-LR nanobody is shown in SEQ ID NO.3 or SEQ ID NO.4.

[0029] In some embodiments, the application of antimicrocystin-LR nanobodies in the detection and / or monitoring of environmental water bodies.

[0030] Specifically, environmental water bodies can include surface water such as rivers, lakes, reservoirs, canals, and streams; groundwater such as shallow and deep groundwater; nearshore water such as estuaries, bays, and nearshore seawater; and artificial water bodies such as aquaculture pond water, landscape water bodies, and sewage treatment plant effluent.

[0031] In some embodiments, the antimicrocystin-LR nanobody is used to detect and / or monitor the content of microcystin-LR in environmental water.

[0032] In some embodiments, the application of antimicrocystin-LR nanobodies in the monitoring of aquatic food and / or water-based food safety.

[0033] In some embodiments, antimicrocystin-LR nanobodies are used to detect microcystin-LR residues in aquatic foods and / or water-based foods.

[0034] In some embodiments, aquatic foods include fish, crustaceans, or shellfish; water-based foods include drinking water, fruit juice, or carbonated beverages.

[0035] Specifically, aquatic foods can include fish such as crucian carp, carp, grass carp, and silver carp; crustaceans such as river shrimp, crayfish, and river crabs; shellfish such as snails and clams; and drinking water such as purified water or bottled mineral water.

[0036] In some embodiments, the present invention provides a detection tool for antimicrocystin-LR, including antimicrocystin-LR nanobodies.

[0037] In some embodiments, the detection tool is any one of a test strip, an immunoassay kit, an immunoaffinity column, a biosensor detection chip, or a detection probe.

[0038] In some embodiments, the present invention provides a photocatalyst for targeted degradation of microcystin-LR, comprising a carrier layer, a photocatalytic active layer, and a targeted recognition layer; the targeted recognition layer is an anti-microcystin-LR nanobody.

[0039] Example 1: Screening of anti-microcystin-LR nanobodies

[0040] 1. Coupling BSA-MC-LR: BSA (bovine serum albumin) and NHS-SH (N-hydroxysuccinimide-thiol) were dissolved separately in NaHCO3 (pH=8.6), mixed at a ratio of 1:6, and reacted at room temperature in the dark for 30 min. Desalting was performed using a desalting column, followed by reduction with tris(2-carboxyethyl)phosphine hydrochloride (TCEP). The pH was adjusted to 12, and microcystin-LR (MC-LR) was added and reacted at room temperature in the dark for 2 h. Desalting was then performed using a desalting column to prepare BSA-MC-LR (bovine serum albumin-microcystin-LR).

[0041] 2. Nanobody Panning: Dissolve BSA-MC-LR at 50 μg / mL in 100 μL of PBS buffer (phosphate buffer), and simultaneously coat 300 μL of 1.5% BSA in the wells of a polystyrene plate. Incubate overnight at 4°C. Wash the BSA wells three times with 0.25% PBST, and add 10... 11100 μL of phage was added to the BSA-coated wells and incubated at 37°C for 1 h, repeated twice. The BSA-MC-LR wells were washed three times with 0.25% PBST (phosphate buffer containing Tween 20), and the pre-adsorbed phage was added. The wells were incubated at 37°C for 1 h. After incubation, the supernatant was discarded, and the wells were washed 10 times with 0.25% PBST. The wells were then eluted with 92.5 μL of 0.1 M Glycine-HCl (pH=2.2) for 8 min, followed by neutralization with 7.5 μL of Tris-HCl (pH=9.0). 10 μL of the elution buffer was used to determine the titer. The remaining 90 μL of elution buffer was added to re-activated ER2738 *E. coli* for amplification. The amplified phage was then used for the next round of screening.

[0042] To obtain nanobodies with high affinity for the antigen, four rounds of screening were conducted. The screening conditions and experimental parameters for each round are shown in Table 1. The anti-microcystin-LR nanobodies were obtained after the fourth round of screening.

[0043] Table 1. Selection conditions and experimental results of anti-MC-LR nanobodies

[0044]

[0045] 3. Indirect Phage-ELISA (phage enzyme-linked immunosorbent assay) to identify phage-positive clones: 144 single-clone phages were randomly selected from plates with titers of the eluents from the third and fourth rounds of panning for amplification;

[0046] Experimental group: BSA-MC-LR was diluted with PBS buffer to a concentration of 2 μg / mL, 100 μL was added to each well, and the mixture was incubated overnight at 4°C; Control group: BSA was diluted with PBS buffer to a concentration of 2 μg / mL, 100 μL was added to each well, and the mixture was incubated overnight at 4°C.

[0047] After coating, wash three times with 0.25% PBST solution, block with 1% gelatin (300 µL / well), and incubate at 37°C for 2 h. After blocking, wash three times with 0.25% PBST solution, add 100 µL of phage amplification buffer to each well, and incubate at 37°C for 1 h. After incubation, wash four times with 0.25% PBST solution, add 100 µL of diluted anti-M13-HRP secondary antibody (final concentration 0.275 µg / mL) to each well, and incubate at 37°C for 1 h. After incubation, wash five times with 0.25% PBST solution, add 100 µL of TMB (3,3',5,5'-tetramethylbenzidine) chromogenic solution to each well, and incubate at 37°C in the dark for 10 min. After chromogenic reaction, add 50 µL of 2M H2SO4 stop solution to each well to stop the reaction. OD was measured using a microplate reader. 450 nm Absorption value at;

[0048] Positive clones are phage clones with a ratio greater than 5 between the experimental and control groups, such as... Figures 1-3 As shown, Figure 1 For the third and fourth rounds of screening, 1-48 monoclonal phage-ELISA results, Figure 2 For the third and fourth rounds of screening, 49-96 monoclonal phage-ELISA results were used. Figure 3 Results of the third and fourth rounds of screening for 97-144 monoclonal phage-ELISA.

[0049] (4) Competitive ELISA identification of positive clones and sequencing results: Dilute BSA-MC-LR concentration to 2 μg / mL with PBS buffer, add 100 μL to each well, and coat overnight at 4℃; after coating, wash 3 times with 0.25% PBST solution, block with 1% gelatin, 300 µL / well, 37℃, 1.5 h; after blocking, wash 3 times with 0.25% PBST solution, add 50 μL of phage amplification buffer, and then add 50 μL of MC-LR (0, 10, 50, 100, ...) to each well. 500 ng), incubate at 37℃ for 1 h; after incubation, wash 4 times with 0.25% PBST solution, add 100 µL / well of HRP / anti-M13 (0.275 μg / mL), and incubate at 37℃ for 1 h; after incubation, wash 5 times with 0.25% PBST solution, add 100 µL / well of TMB chromogenic solution (A and B solutions mixed 1:1), and incubate at 37℃ for 10 min; add 50 μL / well of 2M H2SO4 stop solution to stop the reaction; measure OD using a microplate reader. 450nm Absorbance value.

[0050] Positive phage clones (pComb3XSS-20 and pComb3XSS-119) were sequenced using the Sanger method. The antimicrocystin-LR nanobody had the amino acid sequence shown in SEQ ID NO.1 or SEQ ID NO.2; the nucleotide sequence encoding the antimicrocystin-LR nanobody was shown in SEQ ID NO.3 or SEQ ID NO.4.

[0051] amino acid sequence:

[0052] MC-LR-20: EVQVVESGGGLVQPGGSLRLSCAASEVIAGYYTVAWYRQAPGKQRELVAGLAFGGARIYSQNHEGRFTISRDSAAMYLQMNNLRPEDTAIYYCNARRQSIGTLRDSDFGSWGQGIQVTVSSEPKTPKPQP (SEQID NO.1);

[0053] MC-LR-119: EVQVVESGGGLVRAGGSLRLSCAASGRAFGELSLAWFRQAPGKDREFVAAIHRRAALTVYEDSVKGRFAISRDNAKNTLYLQMNSLKPEDTATYYCYARRGLSYEYWGQGTHVTVSSEPKTPKPQP (SEQ ID NO.2).

[0054] Nucleotide sequence:

[0055] MC-LR-20: GAGGTGCAGGTGGTGGAGTCGGGGGGAGGCTTGGTGCAGCCTGGGGGGTCTCTGAGACTCTCCTGTGCAGCCTCTGAAGTCATAGCGGGTTATTATACCGTAGCCTGGTACCGCCAGGCTCCAGGAAAGCAGCGCGAGTTGGTCGCGGGTCTTGCTTTTGGTGGTGCTCGAATTTATTCCCAGAATCACGAGGGCCGATTCACCATCTCCAGAGACAGCGCCGCAATGTATCTGCAAATGAACAATCTGAGACCTGAGGACACGGCCATCTATTACTGTAATGCCCGAAGGCAGAGCATAGGGACATTGAGAGATTCGGATTTTGGTTCCTGGGGCCAGGGGATTCAGGTCACCGTCTCATCGGAACCCAAGACACCAAAACCACAACCA (SEQ ID NO.3);

[0056] MC-LR-119: GAGGTGCAGGTGGTGGAGTCTGGGGGAGGATTGGTGCGCGCTGGGGGCTCTTTGAGACTCTCCTGTGCAGCCTCTGGACGCGCCTTCGGGGAACTAAGTCTGGCTTGGTTCCGCCAGGCCCCAGGGAAGGATCGTGAGTTTGTAGCAGCTATTCATAGGCGTGCTGCTTTGACAGTCTATGAGGAC TCCGTGAAGGGCCGATTCGCCATCTCCAGGGACAACGCCAAGAACACACTGTATCTTCAAATGAACAGCCTGAAACCAGAGGACACAGCCACTTATTACTGTTATGCCCGACGAGGTTTGTCATATGAGTACTGGGGCCAGGGGGACCCACGTCACCGTCTCCTCAGAACCCAAGACACCAAAACCACAACCA (SEQ ID NO.4).

[0057] Example 2: Expression and purification of anti-microcystin-LR nanobody

[0058] 1. The positive monoclonal phage vectors pComb3XSS-119 and pComb3XSS-20 obtained from Example 1 were constructed as pET22b-119-C4-SBP and pET22b-20-C4-SBP, respectively. They were transformed into Rosetta competent cells by heat shock at 42°C for 90 seconds, plated on 2YT / Amp resistant plates, and single colonies were picked the next day.

[0059] 2. Add the above single colony and 5 μL of 100 mg / mL ampicillin (Amp) to 5 mL of 2YT liquid medium, and incubate at 37°C and 180 rpm for 12 h to obtain the bacterial culture.

[0060] 3. Inoculate the above bacterial culture at a rate of 1% (v / v) into 192 mL of self-induction medium, and add 8 mL of saccharide stock solution and 100 μL of 100 mg / mL ampicillin; culture at 37°C and 180 rpm for 3 h until the logarithmic phase (OD600 reaches 0.5-0.7), then change the culture conditions to 23°C and 130 rpm and induce for 16 h to induce protein expression;

[0061] 4. Centrifuge the expressed bacterial culture at 8000 rpm for 10 min to obtain bacterial cells. Add 10 mL of purification solution A, mix well, centrifuge at 8000 rpm for 10 min, discard the supernatant, and resuspend in purification solution A to a volume of 30 mL. Add 15 mg of lysozyme to a final concentration of 0.5 mg / mL, and incubate at room temperature on a shaker for 1 h. Use a cell sonicator to disrupt the bacteria. Centrifuge the disrupted product at 13000 g, 4 °C for 30 min to obtain the protein supernatant.

[0062] 5. Rinse the purification column with 40 mL of 20% ethanol to remove impurities, then rinse with 40 mL of pure water. Add 2 mL of Ni-NTA packing material to the column, allow it to settle naturally, and then equilibrate the column with 40 mL of purification solution A. Load the sample supernatant onto the column three times, shaking well to allow the target protein to bind to the Ni-NTA packing material for 10 min, and collect all flow-through. Then wash with 40 mL of imidazole-containing equilibration buffer, and perform stepwise elution using a gradient of imidazole concentrations (10%, 20%, 50%, 100%), with the lower concentration used to remove contaminating proteins. Collect each gradient elution fraction and prepare samples. After sample preparation, perform SDS-PAGE electrophoresis, stain with Coomassie Brilliant Blue, and detect the position of the target band.

[0063] SDS-PAGE identified purified antimicrocystin-LR nanobodies 119-C4-SBP and 20-C4-SBP as follows: Figure 4 and Figure 5 As shown, the results indicate that the molecular weights of the bands corresponding to the antimicrocystin-LR nanobodies 119-C4-SBP and 20-C4-SBP are approximately between 25-33 kDa, which is consistent with the theoretical molecular weight range of the fusion protein of nanobodies (15 kDa) and SBP tags (10 kDa). This indicates that the purified antimicrocystin-LR nanobodies 119-C4-SBP and 20-C4-SBP were successfully obtained.

[0064] 6. Transfer the solution containing the target protein to a 3500 Da dialysis bag and dialyze to PBS at 4°C for desalting. Change the dialysis solution every 8 hours for a total dialysis time of 48 hours.

[0065] 7. After dialysis, place the dialysis bag in PEG8000 and concentrate it to a volume of 2 mL at 4℃, and determine the protein concentration. After the determination, add glycerol to a final concentration of 50%, aliquot into 600 μL centrifuge tubes, and store in a freezer at -80℃.

[0066] 8. IC50 determination: Dilute BSA-MC-LR to 2 μg / mL with PBS buffer, add 100 μL to each well, and coat overnight at 4℃. After coating, wash three times with 0.25% PBST solution, block with 1% gelatin (300 µL / well), and incubate at 37℃ for 1.5 h. After blocking, wash three times with 0.25% PBST solution, add 50 μL of phage amplification buffer, and then add 50 μL of MC-LR (0, 10, 20, 40, 80, 160, 320, 6) respectively. 40 ng), incubate at 37℃ for 1 h; after incubation, wash 4 times with 0.25% PBST solution, add 100 µL / well of HRP / anti-M13 (0.275 μg / mL), and incubate at 37℃ for 1 h; after incubation, wash 5 times with 0.25% PBST solution, add 100 µL / well of TMB chromogenic solution (A and B solutions mixed 1:1), and incubate at 37℃ for 10 min; add 50 μL / well of 2M H2SO4 stop solution to stop the reaction; measure OD using a microplate reader. 450nm Absorbance value.

[0067] The IC50 assay results for anti-microcystin-LR nanobodies 20-C4-SBP and 119-C4-SBP are as follows: Figure 6 As shown in the results, both the antimicrocystin-LR nanobodies 20-C4-SBP and 119-C4-SBP can specifically bind to microcystin-LR.

[0068] In summary, this invention utilizes phage display technology to screen and obtain nanobodies with high affinity and high specificity for recognizing microcystin-LR, exhibiting advantages such as strong stability and ease of large-scale expression. Based on anti-microcystin-LR, various detection tools can be designed, including test strips, immunoassay kits, immunoaffinity columns, biosensor chips, or detection probes. This provides novel antibody resources for the rapid monitoring of microcystin-LR and lays a material foundation for developing low-cost, high-performance immunoassay technologies, which is of great significance for promoting the monitoring and control of microcystin-LR pollution.

[0069] The antimicrocystin-LR obtained by this invention can be used to detect and / or monitor the content of microcystin-LR in environmental water bodies, conduct pollution monitoring and early warning, and provide timely pollution warning and decision support for environmental management departments; it can also be used to detect the residual amount of microcystin-LR in aquatic foods and / or water-based foods, conduct food safety monitoring, and protect the health of consumers.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An anti-microcystin-LR nanobody, characterized in that: The amino acid sequence of the antimicrocystin-LR nanobody is shown in SEQ ID NO.1 or SEQ ID NO.

2.

2. The antimicrocystin-LR nanobody as described in claim 1, characterized in that: The nucleotide sequence encoding the antimicrocystin-LR nanobody is shown in SEQ ID NO.3 or SEQ ID NO.

4.

3. The application of the antimicrocystin-LR nanobody as described in claim 1 or 2 in the detection and / or monitoring of environmental water bodies.

4. The application as described in claim 3, characterized in that: The antimicrocystin-LR nanobody is used to detect and / or monitor the content of microcystin-LR in environmental water bodies.

5. The application of the antimicrocystin-LR nanobody as described in claim 1 or 2 in the monitoring of aquatic food and / or water-based food safety.

6. The application as described in claim 5, characterized in that: The antimicrocystin-LR nanobody is used to detect microcystin-LR residues in aquatic foods and / or water-based foods.

7. The application as described in claim 6, characterized in that: The aquatic foods include fish, crustaceans, or shellfish; the water-based foods include drinking water, fruit juice, or carbonated beverages.

8. A detection tool for antimicrocystin-LR, characterized in that: Including the antimicrocystin-LR nanobody as described in claim 1 or 2.

9. The detection tool for antimicrocystin-LR as described in claim 8, characterized in that: The detection tool can be any one of the following: test strip, immunoassay kit, immunoaffinity column, biosensor detection chip, or detection probe.

10. A photocatalyst for targeted degradation of microcystin-LR, characterized in that: It includes a carrier layer, a photocatalytic active layer, and a target recognition layer; the target recognition layer is the antimicrocystin-LR nanobody as described in claim 1 or 2.

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