XPS and ATR‐FTIR study on chemical modifications of cold atmospheric plasma (CAP) operated in air on the amino acids L‐proline and trans‐4‐Hydroxy‐l‐proline

Abstract

Amino acids L-proline and trans-4-Hydroxy-L-proline were exposed to cold atmospheric plasma (CAP) generated by dielectric barrier discharge and operated in ambient air at dry conditions. Surface analysis reveals an oxygenation of both amino acids the degree of which is dependent on treatment time. New NO À 3 or NO 2 groups are attached to the surfaces. Proline and hydroxyproline respond differently to the cold atmospheric plasma, proline being more prone to ring opening, fragmentation of the molecule, and attachment of C─OH and CO groups. Aging experiments show that plasma mediated attachment of new functional groups is, to a great degree, reversible over time.

In situ FTIR spectroscopy study on biomolecular etching by atmospheric pressure plasma jets

“…The chemical modifications of dried amino acids or proteins induced by plasmas reported by previous studies include methionine and cysteine overoxidation (to sulfonic acid) [20,42], carbonyl and hydroxyl band introduction [19,34], and nitric acid ester (N-O or NO 2 sym. stretch) generation [35].…”

“…Such differences may be explained by the varied electron density distributions or bind energies, which lead to the preferential attack of reactive oxygen and nitrogen species, e.g. carbon is more vulnerable to be attacked when it is in the configuration of CH 2 NH 2 + due to the negative inductive effect of the amino group [34,35]. In turn, the configuration of C-OH must have similar effects.…”

Surface decontamination by atmospheric pressure plasma jet: key biological processes

“…Note that moderate surface modification is enough to induce the death of living cells. Modification mainly happens on the surface (nm-µm) of the treated samples, which can be characterized by FTIR spectroscopy [24,45,46] or x-ray photoelectron spectroscopy (XPS) [47,48]. Both DBD and APPJ can bring about chemical modifications to the treated samples.…”

“…This is partially due to the fact that the transmission FTIR mainly reveals the information of the bulk but not (or less) the superficial profiles of samples. In this regard, attenuated total reflectance (ATR) FTIR spectroscopy could be another choice since it has a detection depth of 0.5-2 µm [47]. In-situ ATR FTIR measurement under direct exposure to the plasma jet is possible to achieve, in which case modification and etching profiles may be inspected simultaneously.…”

Decorated Magnetic Nanocatalyst with Trinitriloacetic Acid as a Heterogeneous Catalyst used in the Synthesis of Pyrimido[4,5]quinoline‐2,4‐diones

“…The analytical comparative vibrational peak data of these FTIR curves was summarized after more precise interpretation by comparison of these curves with various references. [14,40,[42][43][44][45][46][47][48][49] According to Figure 7, the formation of Fe 3 O 4 nanopatricles (15) during step 2 1 of the synthetic pathway of 26 (Scheme 1), is evidenced by clear absorption peaks of stretching vibrations at 519 cm À 1 for OÀ Fe(II)À O, 598, 665, and 775 cm À 1 for Fe-(III)À OÀ Fe(II), 683 cm À 1 for OÀ Fe(III)À O, and 808 cm À 1 for the 4 atom ring pulse (… Fe(III)À OÀ Fe(III)À O …). Also, in the experimental FTIR spectrum of Fe 3 O 4 , the small and broad peaks at 916 and 960 cm À 1 are related to FeÀ OÀ H bending vibrations.…”