No abstract

The health, economy, and quality of life all over the world are greatly affected by bacterial infections and viral outbreaks. Bacterial cells and viruses, such as influenza, can spread through contaminated surfaces and fomites. Therefore, a possible way to fight these pathogens is to utilize antibacterial and antiviral coatings, which reduce their numbers on contaminated surfaces. Here, we present a novel short peptide that can self-assemble, adhere to various surfaces, and bind different metal ions such as copper, which provides the surface with antibacterial and antiviral properties. For these functions, the peptide incorporates the amino acid 3,4-dihydroxyphenylalanine (DOPA), which provides the peptide with adhesive capabilities; a diphenylalanine motif that induces the self-assembly of the peptide; the metal-binding hexahistidine sequence. Our results demonstrate that the coating, which releases monovalent cuprous ions and hydrogen peroxide, provides the surfaces with significant antibacterial and antiviral properties. Additionally, the coating remains transparent, which is favorable for many objects and especially for display screens.

Emulsions are commonly used for drug delivery, yet they are usually limited to exclusively delivering either lipophilic compounds or hydrophilic compounds. This separation negates possible synergetic therapeutic roles between such compounds. Here, we introduce a novel design for a short peptide that can stabilize emulsions. Upon binding certain metal ions, the peptide acts as a molecular switch, changes conformation, and becomes amphiphilic. Spectroscopic methods, NMR, and molecular dynamics provide information on the mechanism of this complexation-triggered amphiphilicity. The stability of these unique emulsions is based on histidine-metal bonds, which break at low pH values, selectively releasing their contents at the extracellular pH of tumors. Paclitaxel-encapsulated emulsion demonstrated strong activity against HeLa cells with an IC50 of 70 nM, possibly enhanced by the simultaneous release of Zn2+ ions. Importantly, the emulsion was easily functionalized with various hexahistidine-tagged motifs that can supply the emulsions with many functions beyond drug delivery.