Optimum design of amphiphilic polymers bearing hydrophobic groups for both cell surface ligand presentation and intercellular cross-linking

<div><p>Amphiphilic polymers bearing hydrophobic alkyl groups are expected to be applicable for both ligand presentation on the cell surface and intercellular crosslinking. To explore the optimum design for each application, we synthesized eight different acyl-modified dextrans with varying molecular weight, alkyl length, and alkyl modification degree. We found that the behenate-modified polymers retained on the cell surface longer than the palmitate-modified ones. Since the polymers were also modified with biotin, streptavidin can be presented on the cell surface through biotin-streptavidin recognition. The duration of streptavidin on the cell surface is longer in the behenate-modified polymer than the palmitate-modified one. As for the intercellular crosslinking, the palmitate-modified polymers were more efficient than the behenate-modified polymers. The findings in this research will be helpful to design the acyl-modified polymers for the cell surface engineering.</p></div

Short Peptide Motifs for Long-Lasting Anchoring to the Cell Surface

A rational design strategy has been developed for the construction of stable peptide-based anchors for the efficient modification of cell surfaces. Six types of peptide composed of five residues with divalent hydrophobic groups have been designed using this new strategy. Among them, a peptide with a sequence of NBD-Lys-Lys­(X)-Lys-Lys-Lys­(X)-NH₂ (NBD: fluorophore, Lys­(X): <i>N</i>-ε-palmitoyl-l-lysine) was found to show the highest modification efficacy and longevity in culture medium. The good performance of this peptide was attributed to (1) its high aqueous solubility, which allowed it to partition from the medium to the cell surface, and (2) the high binding affinity of the saturated palmitoyl groups to the cell membrane. We found that the distribution of the peptide was affected by recycling endosome, which enabled the representation of the peptide following its endocytotic disappearance from the cell membrane. Biotin was also presented on the cell surface using this peptide-based anchor to examine its recognition by streptavidin. The efficacy of the recognition process increased as the length of the oligoethylene glycol spacer increased, indicating that it was necessary for the biotin tag to move away from the membrane glycoproteins on the cell surface to facilitate its efficient recognition by streptavidin

Use of Membrane Potential to Achieve Transmembrane Modification with an Artificial Receptor

We developed a strategy to modify cell membranes with an artificial transmembrane receptor. Coulomb force on the receptor, caused by the membrane potential, was used to achieve membrane penetration. A hydrophobically modified cationic peptide was used as a membrane potential sensitive region that was connected to biotin through a transmembrane oligoethylene glycol (OEG) chain. This artificial receptor gradually disappeared from the cell membrane via penetration despite the presence of a hydrophilic OEG chain. However, when the receptor was bound to streptavidin (SA), it remained on the cell membrane because of the large and hydrophilic nature of SA