Creative Biolabs is pleased to offer customized library construction services under a variety of phage display systems. Our scientists have extensive experience in library construction and are professional in generating different types of phage display libraries, including scaffold libraries, peptide libraries, antibody libraries, cDNA libraries and others.

Phage Display Library Types

• Antibody library construction service
• Scaffold library construction service
• Peptide library construction service
• cDNA library construction service

Antibody Library (Immune, Naïve, Semi-synthetic, Synthetic)

Creative Biolabs can display the interest antibody in either scFv or Fab format to construct a high-quality antibody library. Due to the smaller size, scFv libraries are genetically more stable than Fab libraries, while Fab libraries lack the tendency to form higher molecular weight species, such as dimers and trimers, which can simplify the selection and characterization. Moreover, both human plasma cells and splenocytes from naïve or immune animals can be accepted as repertoire source for our antibody library construction service. In addition, Creative Biolabs is able to generate fully or semi-synthetic antibody libraries as well.

Scaffold Library

Creative Biolabs is able to generate high-quality phage display libraries for a comprehensive list of scaffolds. Our scientists devote to offer customized service to design specific scaffold based on clients’ demands. In addition, to achieve 100% precise mutant and over 10¹⁰ diversity, both trimer codon technology and NNK method are used in the library construction resulting in an increased randomicity, which enables the library to be more suitable for sorting and isolating the high-affinity protein or peptide targets.

Peptide Library (Naïve, Semi-synthetic)

To form a peptide library, Creative Biolabs can generate constrained structures with target-adapted cross-links for both naïve and semi-synthetic peptides. This structure contributes to maintaining or increasing a series of properties of peptides, such as stability, permeability, binding affinity and resistance to protease activity. Furthermore, for peptide libraries with inserts longer than 8-mer (and up to 30-mer), three nucleotide doping strategies (NNK, Split-mix-split synthesis, and Trimer codon) can be adopted to maximize the amino acid sequences encoded by the inserted DNA sequences.

cDNA Library

According to our advanced phage display platform, Creative Biolabs is capable of displaying entire cDNA products on the surface of appropriate phage system. Compared with conventional cDNA libraries, our high-quality libraries can achieve higher capacity, density, and correct orientation, which further contribute to the investigation of a lot of protein candidates. Moreover, there are various types of cDNA libraries, including standard library, full-length library, normalized library and subtractive library, can be tailored to match our clients’ demands.

Diversity of Semi-synthetic/Synthetic Libraries

In general, Creative Biolabs employs three main approaches to design semi-synthetic or fully synthetic libraries with appropriate diversity. Our scientists normally generate libraries with a diversity of 10⁸, while we are also able to generate libraries over 10¹⁰ or follow our clients’ specific requirements.

• Hard randomization: complete diversity is introduced by using degenerate codons encoding all twenty natural amino acids.
• Tailored randomization: incomplete or biased diversity is introduced by using degenerate codons encoding a subset of natural amino acids.
• Diversification: degenerate codons are synthesized using trimer phosphoramidites corresponding to 20 natural amino acids, which exclude stop codons.

Table 1. Different phage display vehicles and their characteristics (Ebrahimizadeh and Rajabibazl 2014)

λ Phage

In addition to regular M13, T7 or T4 phage, λ phage is an ideal vehicle to carry the DNA fragments due to its simple structure and flexible DNA. By employing multiple lambda vectors, Creative Biolabs can offer specific genome library construction service to generate qualified genome library with over 95% coverage from either genomic DNA, chromosomes or microbes. In addition, our professional scientists are also available to generate lambda based cDNA library as an alternative service.

As one of the most famous industry leaders who is skilled in advanced phage display technology, Creative Biolabs not only concentrates on developing cutting-edge technology but also be willing to share our state-of-the-art platforms and sufficient expertise with our clients to promote their brilliant studies. It is our guarantee to provide customers with the best services and finest results at Creative Biolabs.

Reference

1. Ebrahimizadeh, W. and Rajabibazl, M. (2014) 'Bacteriophage vehicles for phage display: biology, mechanism, and application', Current microbiology, 69(2), 109-120.

Published Data

• Antibody Discovery

Fig. 1 C5H9v2 monoclonal antibody is a high-affinity blocker of PD-L1 and can potentiate T-cell responses. (Hikmat H. Assi, 2021)

In this article, a PD-L1-blocking antibody was used to develop a novel protease-activatable antibody prodrug, known as Probody therapeutics (Pb-Tx) with the aim of reducing the systemic toxicity of traditional anti-PD-1/PD-L1 therapy while maintaining immune responses to tumors. Probody therapy is able to target antibody activity by attenuating the ability to bind antigen until protease activation in the tumor microenvironment, and its local PD-1/PD-L1 inhibition can elicit robust anti-tumor immunity and minimize systemic immune-mediated toxicity. Through this research, one of the main problems in traditional immunotherapy is solved, which is how to reduce damage to the patient's normal cells, thereby improving the safety and effectiveness of the treatment. While the scientists were conducting their research, Creative Biolabs contributed to the discovery of PD-L1 blocking antibodies. We identified this potent antibody from a fully human single-chain variable fragment (scFv) phage display library using recombinant His-tagged human or mouse PD-L1 extracellular domains.

• Custom Phage Display Library Construction

Fig. 2 Viruses used in bionanotechnology. (Carissa M Soto, 2010)

This article describes the progress in the field of biological nanotechnology, in which viruses are used as tools for biological nanotechnology to create nanostructured materials. Scientists use genetic engineering to modify the viral capsid so that it can act as a protein cage, scaffold, and template for assembling nanomaterials. This method allows precise and controlled integration of organic and inorganic molecules for the development of a variety of nanomaterials and for biosensing, memory devices, nanocircuits, light-harvesting systems, and nanobatteries.

Various nanomaterials produced by rod and spherical viruses mainly include tobacco mosaic virus (TMV), M13 bacteriophage, cowpea chlorosis mottle virus (CCMV), and cowpea mosaic virus (CPMV). M13 bacteriophage is a filamentous phage of Escherichia coli and a well-known cloning vector that has been used to express or display engineering peptides on the surface of the virus without affecting its natural biological characteristics. M13 phage has also been used as a phage display to express small peptides and antibodies. This display technique can produce high affinity and specific human antibodies without immunity. In addition, M13 bacteriophage can also be used to produce engineering antibodies with specific specificity and stability, as well as cell signal peptides for the identification of tissue regeneration materials. For such engineering applications, Creative Biolabs has created a combinatorial library to produce a large number of bacteriophages displaying various amino acids. The availability of premade and customized phage libraries from Creative Biolabs makes it possible to make full use of phage display technology in material science.

FAQ

• What is the principle of phage display technology?[↑Top]

1. Phage display technology fuses and displays exogenous peptides and phage capsid proteins on the surface of phages, performs high-throughput screening and enrichment, and conducts qualitative analysis of clones with required functions. The display objects of this technology are antibodies, antibody fragments, peptides, cDNA, and so on.

• What are the advantages of phage display in the construction of antibody libraries?[↑Top]

1. In the study of antibody libraries, phage display technology can construct and screen the B cell antibody libraries of humans and other animals in vitro, avoiding the steps of immunity and cell fusion so as to shorten the experimental cycle and increase stability. The technology also has the advantages of large screening capacity, mass fermentation production, simple experimental method, and so on.

• What research directions can phage display technology be applied to?[↑Top]

1. According to the different display molecules, it can be roughly divided into the following two categories:
   1) Protein/antibody: diagnostics, drug navigation, protein structure analysis, humanized modification, and customization of scientific research antibodies.
   2) Random peptide library: protein-protein (ligand receptor, information transmission, antagonist/inhibitor, etc.), protein-DNA, diagnostics, neutralization activity, drug and drug navigation, enzyme, and substrate.

• What are the screening methods for phage display?[↑Top]

1. There are two main screening methods for phage display: magnetic bead labeling and immune tube screening. The difference between the two is that the former has more positive clones, while the latter has fewer positive clones but higher affinity. In general, the magnetic bead labeling method is preferred for screening, and then it is decided whether or not to increase the immune tube screening step according to the results. The basic principle of the two methods is the specific binding of antigens and antibodies.

• How can the screening process displayed by bacteriophages ensure that the antibodies that are screened for interference can retain the desired antibodies?[↑Top]

1. The principle of selection is actually an experimental process based on the specific reaction between antigens and antibodies. Specifically, the specific binding between the antibody sequence displayed on the surface of the phage and the antigen makes the specific antibody sequence continuously enriched. However, in the process of screening, there must be non-specific binding between bacteriophages of 10¹² or higher and antigens, so after the screening is over, another ELISA identification will be carried out to exclude the non-specific binding antibody clones. Secondly, if there are several highly homologous targets that need to be distinguished at the same time, a closed group can be set up to seal off the cross-binding positive clones in advance, and the remaining phage library can be used to screen specific targets.

• How much will be detected by monoclonal clone sequencing in the phage antibody library?[↑Top]

1. For the evaluation of the antibody library, 20–50 clones are randomly selected and sequenced to evaluate the diversity and titer of antibodies.
2. For the positive clones after screening and ELISA detection, the 10-15 clones with the best ELISA results are generally selected for sequencing.

• What is the capacity of the phage antibody library finally obtained? How to ensure that the coverage meets the requirements after repackaging?[↑Top]

1. Finally, the phage antibody library was 20–30 ml, and each tube of 1 ml was assembled separately. In general, as long as the number of clones in each tube is more than ten times the capacity of the library, all the sequences can be guaranteed. If the capacity of the immune antibody library is 10⁹, as long as the concentration of bacterial liquid in each tube is more than 10¹⁰, all antibody sequences can be covered.

Resources

Use the resources in our library to help you understand your options and make critical decisions for your study.

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