Plasma enhanced vapor deposition of dipeptide nanostructures: nanotubes to nanoflowers

The study of self-assembling peptides for synthesizing nanomaterials is a rapidly growing area in biomedical research. In this study, we report a hybrid deposition technique, plasma enhanced chemical vapor deposition (PECVD), as a reliable method for the synthesis of aromatic tyrosine peptide-based nanostructures with well-defined structural and physicochemical properties. In the custom-built PECVD system, deposition parameters, including the deposition height, substrate tilt, chamber pressure, frequency of plasma pulsation, and presence of physical confinement, were varied, leading to the formation of thin films with desired morphologies, uniformity, and stability. Morphological characterization revealed that the conditions during deposition could be varied to form nanotubular-like structures, whereas higher pressure and the presence of physical confinement led to the emergence of nanoflower-like structures. Nanoflowers are nanostructures with a high surface area-to-volume ratio and a large number of effective sites featuring multilayered porous "petal" structures that extend radially from centralized nucleation sites. Spectroscopic analysis confirmed the simultaneous preservation of peptide chemistry, alterations in the secondary structure, and increased crystallinity, suggesting molecular reorganization. These results provide insights into the plethora of opportunities offered by PECVD for applications in catalytic substrates, regenerative medicine, targeted drug delivery, and the development of antimicrobial coatings.