# 1-Pyrene Carboxylic Acid: An Internalization Enhancer for Short Oligoarginines

## TL;DR

Researchers developed a new method to improve cell membrane penetration using modified peptides with 1-pyrene carboxylic acid.

## Contribution

A new modification using 1-pyrene carboxylic acid enhances the internalization efficiency of short oligoarginine peptides.

## Key findings

- Peptides modified with PCA showed remarkable internalization in tumor cell lines.
- PCA modification allows short oligoarginines to rival established CPPs like octaarginine.
- Multiple endocytic pathways are involved in the internalization mechanism of the modified peptides.

## Abstract

Getting through the cell membrane is challenging, and transporting a therapeutic agent while entering the cell is even more complicated. Cell-penetrating peptides (CPPs) are valuable tools for solving this problem, although they have drawbacks. In this work, the synthesis and investigation of efficient CPPs are described. We used an aromatic group, 1-pyrene carboxylic acid (PCA), to enhance internalization. We designed oligoarginines to investigate the effect of PCA in different positions at the N-terminus or in the side chain. Our novel peptide derivatives showed remarkable internalization on tumor cell lines, and more than one endocytic pathway plays a role in their internalization mechanism. With this modification, there is an opportunity to design short oligoarginines that can rival well-known CPPs like octaarginine in internalization.