Cross-linked Triblock Peptide Capsules as Potential Oxygen Carriers.

Perfluorodecalin (PFD)-filled capsules have been studied for over 15 years as artificial oxygen carriers. However, none of these capsules combines good biocompatibility, good mechanical stability and dispersion stability. Here we propose to use synthetic triblock peptides containing a central block of cysteine units as a cross-linking shell material for capsules with both good biocompatibility and stability. Together with outer aspartate units and inner phenylalanine units, the resulting amphiphilic triblock peptides can encapsulate PFD efficiently to prepare capsules with a suitable diameter, a certain mechanical strength, a large diffusion constant, fast gas exchange rates, and little cytotoxicity. Given the above advantages, these PFD-filled peptide capsules are very promising as potential artificial oxygen carriers.

Syntheses of Polypeptides and Their Biomedical Application for Anti-Tumor Drug Delivery.

Polypeptides have attracted considerable attention in recent decades due to their inherent biodegradability and biocompatibility. This mini-review focuses on various ways to synthesize polypeptides, as well as on their biomedical applications as anti-tumor drug carriers over the past five years. Various approaches to preparing polypeptides are summarized, including solid phase peptide synthesis, recombinant DNA techniques, and the polymerization of activated amino acid monomers. More details on the polymerization of specifically activated amino acid monomers, such as amino acid N-carboxyanhydrides (NCAs), amino acid N-thiocarboxyanhydrides (NTAs), and N-phenoxycarbonyl amino acids (NPCs), are introduced. Some stimuli-responsive polypeptide-based drug delivery systems that can undergo different transitions, including stability, surface, and size transition, to realize a better anti-tumor effect, are elaborated upon. Finally, the challenges and opportunities in this field are briefly discussed.