T7 Peptide Modification

Creative Peptides provides T7 peptide modification services to enhance targeted drug delivery by employing transferrin receptor-mediated transport and peptide conjugation techniques, improving peptide stability, bioavailability, and blood-brain barrier penetration for biomedical applications.

What is T7 Peptide?

T7 peptide is an artificially designed targeted peptide derived from the study of the interaction between transferrin and transferrin receptor (TfR). TfR is highly expressed on the surface of blood-brain barrier (BBB) endothelial cells, tumor cells, and rapidly proliferating cells, making it an ideal target for drug delivery. In 2009, the researchers screened T7 peptide through phage display technology, which has 100 times the affinity with TfR and avoids the fluctuation of delivery efficiency caused by the competitive binding of iron ions to transferrin. This discovery addresses the limitations of traditional targeting strategies and provides an efficient delivery tool for brain disease and cancer treatment.

The T7 peptide is composed of seven amino acids and has the sequence HAIYPRH (H-His-Ala-Ile-Tyr-Pro-Arg-His-OH). Its core structure contains two key functional areas:

TfR binding domain: N-terminal histidine and arginine-histidine motifs (R6-H7) are directly involved in TfR binding, mimicking the receptor recognition site of transferrin.

Stability optimization: Through D-type amino acid substitution (such as D-arginine) or polyethylene glycol (PEG) modification, the ability to resist enzymatic hydrolysis and the half-life in vivo are enhanced.

The short peptide is compact in structure, easy to synthesize, and can be adapted to a variety of drugs (such as chemotherapy drugs, nucleic acids, and antibodies) through chemical conjugation or carrier modification, making it a popular molecular tool for breakthroughs in BBB and tumor targeting.

What is T7 Peptide Modification?

T7 peptide modification is a technique in which a T7 peptide is chemically or biologically conjugated to a drug, nanocarrier, or contrast agent to target the TfR with high affinity. The T7 peptide mimics transferrin binding to TfR to trigger receptor-mediated endocytosis to break through the blood-brain barrier or deliver precisely to tumor cells. This technology can enhance the intracerebral concentration of drugs (such as chemotherapy drugs, nucleic acid drugs), reduce systemic toxicity, and adapt to a variety of carriers (liposomes, polymer particles) and diagnostic probes, which are widely used in brain diseases, cancer treatment and real-time imaging, with the advantages of efficient targeting, low immunogenicity and versatility.

Mechanism of T7 Peptide Modification

The core mechanism of T7 peptide modification is based on its ability to target the TfR. By mimicking the interaction between the natural ligand transferrin and TfR, T7 peptide triggers receptor-mediated endocytosis (RMT), enabling efficient transmembrane delivery of drugs or carriers. This process can be broken down into the following key steps:

Specific Binding of T7 Peptide to TfR

TfR is a transmembrane protein highly expressed on the surface of endothelial cells in the BBB, tumor cells, and rapidly proliferating cells, responsible for iron ion transport. T7 peptide binds with high affinity to the extracellular domain of TfR (particularly at the transferrin-binding site) through its core structural domains, such as histidine, arginine (R6), and histidine (H7). Compared to natural transferrin, T7 peptide has a smaller molecular weight (approximately 1 kDa), nearly a hundred times higher binding affinity, and avoids the delivery efficiency fluctuations caused by competition for iron ion binding.

Receptor-Mediated Endocytosis and Transmembrane Transport

Once T7 peptide binds to TfR, the cell membrane invaginates to form a clathrin-coated vesicle, internalizing the conjugate (such as drugs, nanoparticles, or nucleic acids) through a clathrin-dependent endocytosis pathway. The vesicle then sheds the clathrin coat and fuses with early endosomes. In the acidic environment of the endosome, T7 peptide dissociates from TfR, and the conjugates are delivered across the membrane via the following pathways:

Crossing the BBB: Vesicles carrying the conjugates are transported to the brain parenchyma side, where they are released into the brain tissue interstitial space via exocytosis.

Tumor Cell Targeting: After endocytosis in tumor cells, the drug escapes the lysosome (e.g., pH-sensitive carriers break in the acidic environment) or is released into the cytoplasm through carrier degradation.

Drug Release and Mechanism of Action

The T7-modified delivery system achieves controlled release based on the conjugation strategy:

Direct Drug Conjugation (e.g., T7-Paclitaxel): Active drugs are released inside target cells through cleavable linkers (such as protease-sensitive peptide chains).

Nanocarrier Encapsulated Drugs: T7-modified liposomes or polymer particles release drugs in the acidic lysosomal environment or through enzymatic degradation.

Gene Delivery: T7-cationic polymer complexes deliver siRNA/mRNA to the nucleus or cytoplasm through endosomal escape.

Stability and Efficiency Optimization

To improve delivery efficiency, T7 peptides are often modified to enhance stability:

PEGylation: Reduces immune clearance and prolongs circulation half-life.

D-amino acid Substitution: D-arginine replacing the natural L-form resists protease degradation.

Multifunctional Conjugation: Combining with cell-penetrating peptides (CPP) or pH-sensitive modules enhances transmembrane depth or smart release.

T7 peptide modification, through precise targeting, efficient endocytosis, and controlled release mechanisms, significantly increases drug concentration in brain tissue or tumors (up to 5-10 times that of traditional methods), while reducing systemic exposure and toxicity. It has become one of the key technologies for overcoming biological barriers.

Advanced Platform for T7 Modification

Peptide Synthesis and Modification Technology

Creative Peptides provides an advanced platform for the synthesis and modification of T7 peptides, employing solid-phase peptide synthesis (SPPS) technology for precise peptide creation. We offer tailored modifications, including PEGylation, phosphorylation, and glycosylation, to optimize T7 peptides for improved pharmacokinetics and blood-brain barrier (BBB) penetration. Our automated synthesis systems allow for high-throughput production while ensuring each peptide meets the required specifications for targeted delivery and therapeutic applications.

Advanced Analytical and Purification Tools

For rigorous quality control of modified T7 peptides, Creative Peptides uses cutting-edge analytical instruments such as High-Performance Liquid Chromatography (HPLC), Mass Spectrometry (MS), and Nuclear Magnetic Resonance (NMR). HPLC is employed to purify the T7 peptides, ensuring high purity levels. MS helps determine the molecular weight and verify the presence of modifications, while NMR is used for structural analysis, confirming the peptide's conformation and integrity after modification to ensure optimal function for BBB targeting.

Comprehensive Characterization and Quality Control

Creative Peptides integrates comprehensive characterization techniques to assess the quality and functionality of T7 peptide modifications. Our quality control platforms include MALDI-TOF for accurate molecular weight analysis and circular dichroism (CD) spectroscopy for evaluating the peptide's structural properties. These methods ensure that the modified T7 peptides retain their biological activity and are capable of effectively crossing the blood-brain barrier, making them ideal candidates for targeted drug delivery and therapeutic interventions.

Strategy of T7 Peptide Modification

The T7 peptide modification strategy utilizes flexible conjugation techniques and carrier designs to link the T7 peptide with drugs, nucleic acids, imaging agents, or nanoparticles for precise targeted delivery. Key aspects of this approach include the conjugation methods, carrier selection, functional optimization, and application adaptability.

Conjugation Methods

The T7 peptide can be conjugated via cleavable or non-cleavable linkers. Cleavable linkers, such as enzyme-sensitive sequences (e.g., GFLG) or acid-sensitive bonds (e.g., hydrazone), allow drug release within target cells, suitable for tumor environments. Non-cleavable linkers, such as thioether or amide bonds, rely on lysosomal degradation of the carrier to release the drug, ideal for sustained release applications.

Surface modification of carriers such as liposomes, polymer nanoparticles, or exosomes involves coupling the T7 peptide through various chemical reactions, enhancing targeting to the brain or tumors. Additionally, electrostatic adsorption or covalent coupling of T7 with cationic polymers forms stable complexes for gene delivery.

Carrier Selection and Optimization

Liposomes and polymeric particles (e.g., PLGA) are commonly used carriers, with T7 modification enhancing targeting and improving drug delivery. Inorganic carriers, such as gold or iron oxide nanoparticles, offer diagnostic and therapeutic capabilities, particularly for imaging and drug delivery. Multifunctional modules, such as cell-penetrating peptides or stimuli-responsive elements, are integrated to optimize carrier efficiency and drug release in response to specific environmental cues.

Functional Optimization

To improve stability, T7 peptides are often modified with D-amino acids or PEGylation to resist degradation and reduce immune clearance. For enhanced penetration, dual-targeting modifications and size optimization ensure improved delivery efficiency, especially for BBB penetration. Furthermore, linker selection and targeting optimization minimize off-target toxicity, ensuring safer therapeutic outcomes.

Advantages of Our T7 Peptide Modification Service

Application of T7 Peptide Modification

Customized Service Process

FAQs

1. Why is T7 peptide commonly used in drug delivery?

2. What modification strategies are used for T7 peptides?

3. How does T7 peptide modification enhance therapeutic applications?

4. What analytical techniques are used to characterize modified T7 peptides?

5. What factors influence the success of T7 peptide modification?

References

1. Yu, Min-Zhi, et al., Systemic delivery of siRNA by T7 peptide modified core-shell nanoparticles for targeted therapy of breast cancer. European Journal of Pharmaceutical Sciences 92 (2016): 39-48.
2. Zhang, Shuang-Shuang, et al., T7 peptide-mediated co-delivery platform overcoming multidrug-resistant breast cancer: In vitro and in vivo evaluation. European Journal of Pharmaceutics and Biopharmaceutics 200 (2024): 114327.