Peptide Liposome Conjugation

Peptide Liposome Conjugation

As a leading CRO, BOC Sciences is committed to providing custom bioconjugation services. We are capable of providing peptide-liposome conjugation service to propose innovative solutions in the field of drug delivery.


Peptides are an important class of bioactive substances in the organism. Compared with protein, peptide embodies many features of small molecular mass, easy preparation, low immunogenicity, easy diffusion and high targeting, which can meet the requirements of targeting tumors. However, peptide drugs still have application limitations such as unavailability for oral administration, short half-life, and poor cell membrane permeability, which require innovation in molecular design as well as drug delivery technology.

Liposomes as ideal carriers for drugs and bioactive substances are colloidal vesicle-like structures consisting of one or more lipid bilayers that can encapsulate lipophilic, hydrophilic and amphiphilic compounds. They have the advantages of non-toxicity, high biocompatibility and biodegradability. Therefore, coupling of peptide drugs with liposomes is an effective strategy to improve the effective transport of peptide drugs in vivo as well as their efficacy. For oral administration, liposomes not only protect peptide drugs from damage and effects of gastrointestinal enzymes and pH changes, but also easily fuse with intestinal mucosa to facilitate their entry into the body. For injectable drug delivery, through the slow and controlled release of bilayer of liposomes, the half-life of peptide drugs in vivo can be prolonged and the bioavailability can be improved.

Peptides can be conjugated to liposomal surfaces by various covalent linkages, including maleimide-thiol bonds, peptide bonds, thionyl bonds, disulfide bonds, and phosphatidylethanolamine binding, to provide the desired peptide-liposome bioconjugates.

Examples of Peptide-Liposome Bioconjugates

Peptide as a targeting group on liposomes

YIGSR (Tyr-Ile-Gly-Ser-Arg), derived from the sequence of the β1 chain of the laminin (LN) molecule, has an anti-tumor angiogenic effect and can inhibit the growth of tumor metastases and tumor primary site. Attaching YIGSR peptide to the surface of liposome and using liposome as a carrier of YIGSR peptide can reduce the enzymatic destruction of YIGSR peptide in vivo, enhance the anti-metastatic effect, and effectively inhibit experimental lung metastasis and spontaneous lung metastasis.

Peptide GE11 is a small molecule peptide obtained by phage peptide library screening technology, consisting of 11 amino acids (YHWYGYTPQNVI). Studies have shown that GE11 can bind to EGFR specifically and GE11 has no effect on cell growth, and GE11-liposome bioconjugate exhibit high targeting to EGFR.

NGR peptide is a targeting peptide that binds to CD13 receptor on tumor neovascular endothelial cells. NGR peptide was coupled to liposome to obtain NGR peptide-modified liposome. By intravenously injecting this liposome, the NGR polypeptide can bind to CD13 receptors on tumor neovascularization and localize the liposome to the tumor tissue, allowing the drug in the liposome to concentrate at the tumor site, thus improving the anti-tumor effect.

Liposomes as peptide drug carriers

Long-circulating liposomes are mostly modified by hydrophilic macromolecules such as PEG and its derivatives to form a hydrophilic layer on the surface of liposomes to avoid recognition and absorption by the reticuloendothelial system, thus prolonging the circulation time of drugs in the blood. For example, the use of PEG-modified long-circulating liposomes to encapsulate peptides can significantly prolong the retention time and half-life of peptides in vivo.

Due to the good water solubility of most proteins and peptides, traditional liposomes cannot achieve the ideal encapsulation rate, and the drug is prone to leakage and abrupt release, which makes the drug release unsatisfactory. Multicapsular liposomes are large liposomes with multiple non-concentric chambers, which have more encapsulation volume and larger particle size, strong topology and stable properties. More than 95% of them are aqueous chambers, which are very favorable for encapsulation of peptide drugs.

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