Novel hybrid cyclic-linear cell-penetrating peptides with alternating charged and hydrophobic residues showed enhanced cellular uptake and molecular transport capability compared to conventional linear CPPs.
Best of both architecturesHybrid cyclic-linear design combines cyclic stability with linear flexibility, achieving better cellular uptake than conventional CPP designs
What the researchers found
Hybrid cyclic-linear CPPs with alternative positively charged and hydrophobic amino acids showed enhanced cellular uptake and delivery of cell-impermeable, negatively charged molecules.
Why it matters
Better CPP architectures mean more efficient drug delivery into cells. The hybrid approach addresses limitations of both pure linear (unstable) and pure cyclic (rigid) CPPs.
The numbers in context
18-fold uptake increase (CCRF-CEM); 11-fold (SK-OV-3); no toxicity at 10 μM; partial endocytosis independence
How the study worked
Synthesis and biological evaluation of a novel series of hybrid cyclic-linear peptides. Cellular uptake measured with various cargo molecules.
Who was studied
Human leukemia (CCRF-CEM), ovarian cancer (SK-OV-3), kidney (HEK-293), and breast cancer (MDA-MB-231) cell lines
What this study cannot tell us
In vitro uptake study. Cargo diversity limited. In vivo delivery and therapeutic applications not tested. Manufacturing complexity of hybrid peptides.
How to read the evidence
Low evidence grade: in vitro cellular uptake study with novel peptide architecture.
When this study was published
Published 2021.
The bigger picture
CPP design is evolving from simple linear sequences to sophisticated architectures. Hybrid designs that optimize both membrane interaction and cargo binding could become standard platforms for intracellular drug delivery.
Questions still open
- Which hybrid design provides the best balance of uptake efficiency and cargo capacity?
- Can hybrid CPPs deliver therapeutic proteins or nucleic acids in vivo?
- Do hybrid architectures improve peptide stability in biological fluids?
Common questions
What is a hybrid cyclic-linear peptide?
Why alternate positive and hydrophobic amino acids?
Read the original research
Hybrid Cyclic-Linear Cell-Penetrating Peptides Containing Alternative Positively Charged and Hydrophobic Residues as Molecular Transporters.
Molecular pharmaceutics, 18(10), 3909-3919
Citation
Khayyatnejad Shoushtari, Sorour; Zoghebi, Khalid; Sajid, Muhammad Imran; Tiwari, Rakesh Kumar; Parang, Keykavous. (2021). Hybrid Cyclic-Linear Cell-Penetrating Peptides Containing Alternative Positively Charged and Hydrophobic Residues as Molecular Transporters.. Molecular pharmaceutics, 18(10), 3909-3919. https://doi.org/10.1021/acs.molpharmaceut.1c00594