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Cell-penetrating peptides (CPPs)[2]

Updated: 2026-09-15

Overview

Cell-penetrating peptides (CPPs) are typically 5-30 amino acid sequences that can traverse plasma membranes, enabling intracellular delivery of cargo molecules. First discovered in the 1980s with HIV-1 TAT peptide, CPPs have become essential tools in biomedical research and therapeutic development. These peptides utilize various mechanisms for cellular entry, including direct translocation and endocytosis. Their ability to transport diverse payloads—from small molecules to nanoparticles—makes them versatile delivery vehicles. CPPs are classified based on origin (natural, chimeric, synthetic) or physicochemical properties (cationic, amphipathic).

Physical and Chemical Properties

CPPs exhibit distinct biophysical characteristics that enable membrane penetration. Cationic CPPs (e.g., TAT, polyarginine) contain multiple positively charged residues, while amphipathic CPPs (e.g., penetratin) have alternating hydrophobic and hydrophilic regions. The secondary structure significantly impacts penetration efficiency, with many CPPs adopting α-helical or β-sheet conformations. Most are water-soluble but may require optimization of buffer conditions. Stability varies by sequence, with some susceptible to proteolytic degradation unless modified (e.g., D-amino acids, cyclization).

Main Applications

In drug delivery, CPPs conjugate with therapeutics to enhance bioavailability of anticancer agents, nucleic acids, and proteins. They're particularly valuable for delivering membrane-impermeable molecules like siRNA and CRISPR components. Diagnostically, CPPs transport imaging probes for intracellular tracking. Research applications include studying protein-protein interactions and cellular processes. Emerging uses include vaccine development and crossing the blood-brain barrier for neurological therapies.

Safety and Storage

CPPs generally show low cytotoxicity at working concentrations (μM range), but effects are sequence- and cell type-dependent. Always conduct dose-response testing. Some may induce membrane disruption at high concentrations. Store lyophilized peptides at -20°C in airtight containers with desiccant. Reconstituted solutions are typically stable for weeks at 4°C or months at -80°C. Avoid repeated freeze-thaw cycles. Handle with gloves to prevent degradation and contamination.

B2B Procurement Guide

When sourcing CPPs, specify exact sequences, modifications (acetylation, amidation, labels), and purity (typically >95% for research). Custom synthesis services often provide HPLC and MS validation. For large-scale therapeutic use, verify GMP-compliant manufacturing capabilities. Compare delivery efficiency data across vendors. Bulk pricing becomes significant above 100mg quantities. Consider stability data for logistics planning, especially for modified peptides.

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