Investigating the impact of inbuilt cold atmospheric pressure plasma on molecular assemblies of tryptophan enantiomers: in vitro fabrication of self-assembled supramolecular structures.

The advancements in understanding the phenomenon of plasma interactions with matter, coupled with the development of CAPP devices, have resulted in an interdisciplinary research topic of significant importance. This has led to the integration of various fields of science, including plasma physics, chemistry, biomedical sciences, and engineering. The reactive oxygen species and reactive nitrogen species generated from cold atmospheric plasma on interaction with biomolecules like proteins and peptides form various supramolecular structures. CAPP treatment of amino acids, which are the fundamental building blocks of proteins, holds potential in creating self-assembled supramolecular architectures. In this work, we demonstrate the process of self-assembly of aromatic amino acid tryptophan (Trp) enantiomers (l-tryptophan and d-tryptophan) into ordered supramolecular assemblies induced by the reactive species generated by a cold atmospheric pressure helium plasma jet. These enantiomers of tryptophan form organized structures as evidenced by FE-SEM. To assess the impact of CAPP treatment on the observed assemblies, we employed various analytical techniques such as zeta potential, dynamic light scattering and FTIR spectroscopy. Also, photoluminescence and time-resolved lifetime measurements revealed the transfiguration of individual Trp enantiomers. The LC-ESI-QTOF-MS analysis demonstrated that CAPP irradiation led to the incorporation of oxygenated ions into the pure Trp molecule. These studies of the self-assembly of Trp due to ROS and RNS interactions will help us to understand the assembly environment. This knowledge may be utilized to artificially design and synthesize highly ordered functional supramolecular structures using CAPP.

Cold atmospheric plasma driven self-assembly in serum proteins: insights into the protein aggregation to biomaterials.

The self-assembly of proteins is crucial in many biomedical applications. This work deals with understanding the role of cold atmospheric plasma (CAP) on the self-assembly of two different proteins present in the serum - BSA and hemoglobin and to elucidate the process associated with the direct application of physical plasma on or in the human (or animal) body, which has implications in therapeutics. The work has been corroborated by several spectroscopic studies such as fluorescence spectroscopy, circular dichroism spectroscopy, and SEM analysis. Through steady-state fluorescence spectroscopy and by following the tryptophan fluorescence, we observed that the emission intensity was quenched for the protein when treated with plasma radiation. Circular dichroism spectroscopy revealed that the structure of the protein was altered both in the case of BSA and hemoglobin. N-Acetyl tryptophanamide (NATA), which resembles the tryptophan in the protein, was treated with CAP and we observed the similar quenching of fluorescence as in the proteins, indicating that the protein underwent self-assembly. Time-resolved fluorescence spectroscopy with a decrease in the lifetime revealed that the protein self-assembly was promoted with CAP treatment, which was also substantiated by SEM micrographs. The ROS/RNS produced in the CAP has been correlated with the protein self-assembly. This work will help to design protein self-assembled systems, and in the future, may bring possibilities of creating novel biomaterials with the help of plasma radiation.