Iuliana Motrescu

Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure

With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications.

Mechanism of peptide modification by low-temperature microwave plasma

The possibility of changing the biological function of peptides was investigated using low pressure microwave plasma, aiming to develop a new and efficient technique to inactivate biohazardous proteinaceous molecules such as abnormal prions and figure out the insights of the interactions between non-reactive plasmas and peptide molecules. In the present research, a peptide, Arginine Vasotocin, having an inherent bio-function of controlling the water penetrability through amphibian abdominal skin was used. The interaction with low temperature plasma is investigated. The mechanisms involved in the modifications produced by argon plasma exposure are discussed, according to the obtained results of X-ray photoelectron spectroscopy, mass spectrometry, nuclear magnetic resonance, and water penetrability tests. The loss of water enhancement property of the peptide molecules after argon plasma treatment is explained.

Effects of Nitrogen and Oxygen Radicals on Low-Temperature Bio-Molecule Processing

The mechanism by which microwave plasma is able to modify the structure and function of proteinaceous molecules is investigated. The biomolecule cystine, a dimer aminoacid, was exposed to microwave surface wave plasma produced in reactive gases, such as oxygen and nitrogen, in different conditions. Except for the physical interactions of the charged particles with the samples and the photophysical reactions induced mostly by ultraviolet radiation, these plasmas contain reactive species which promote chemical interactions. In this study we focus on the changes of biomolecules due to neutral particles inside reactive plasmas. The results proved that the effects of neutrals and charged species are not cumulative. Moreover, it seems that the charged species inside the nitrogen plasma promote nitrogen addition while the outcome of neutral exposure is cleavage. Strong oxidation occurs for oxygen treatments, most reactive species which cause oxygen addition being the oxygen molecular ions O2+.

Mass spectrometric study of Ar/NH3 surface wave plasma utilized for surface functionalization of ZnO nanoparticles

Owing to its low toxicity toward living organisms and specific optical properties, we promote the use of zinc oxide (ZnO) as an alternative to existing semiconductor-based materials for developing new bioimaging techniques. ZnO nanoparticles (NPs) were prepared using the laser ablation technique in oxygen reactive atmosphere at room temperature by ablating a commercial high-purity ZnO target. The surface functionalization of ZnO NPs was successfully achieved using a dry chemical reactor with ammonia/argon mixture plasma. The roles of various plasma ions in the surface interaction with ZnO NPs were investigated to understand the mechanism of functionalization by quadrupole mass spectrometry.

Novel approach for zinc oxide nanomaterials functionalization based on dry plasma processing

Zinc oxide is a wonderful material for bioimaging applications own to its wide range of properties1,2 among which the photoluminescence at room temperature is to be mentioned. We aim to develop a method for biohazard imaging using ZnO nanoparticles based on this property. Such a technique will firstly need the preparation of nanoparticles as to specific detect the biohazard by bio-functionalization, meaning that firstly functional groups are introduced on the surface of the nanoparticles, then ligand molecules for specific targeting are covalently bound on the functional groups. For the functionalization of the nanoparticles we propose a novel technique that overcomes the numerous issues of existing chemical “in liquid” processing methods (e.g. agglomeration, solubility) - low temperature dry plasma processing3.

Nitrogen plasma modification of cysteine for bioapplications

Summary form only given. Recently, the field of bioapplications has been extending to nano scale where new diagnosis methods are used as non-invasive ways for disease and injury detection and treatment. Due to the high expectations, efforts are done to combine various techniques to reach out to this aim. In this sense, plasma mediated surface processing provides a platform for using nanomaterials in biological and medical applications.

Experimental study of spore etching of microorganisms in oxygen plasma using optical and mass spectroscopy

Utilizing plasma to achieve sterilization is an alternative to conventional sterilization means as far as sterilization of heat-sensitive materials and innocuity of sterilizing agents are concerned. Plasma sterilization is a surface sterilization process due to the limited ability of electrons and charged particles and/or VUV/UV emission generated during the plasma generation. However, plasma sterilization has the remarkable advantage that toxic residues are not produced on the sterilized objects after treatments. In addition, it is not only capable of killing bacteria and viruses, but also capable of removing the dead bacteria and viruses from the surface of the objects being sterilized. There are several mechanisms which may be responsible for the sterilization. These factors are the heat, UV radiation, plasma particles, and reactive neutral species. The extent of the influence of each factor depends on the plasma operating parameters such as power and gas mixture and flow rate. In our previous work, a six-log reduction in spores could be achieved only several minutes irradiation with low-pressure oxygen/air simulated surface-wave plasmas and the chemical etching reaction from the reactive oxygen radicals make more efficient inactivation rate [1-2]. In this work, we follow up to the previous studies[3-4], in order to investigate the contribution of various effects, especially the etching phenomena by the reactive oxygen radicals in the inactivation of spore forming bacteria. The experimental setup used for the sterilization tests consists of a stainless steel cylindrical vacuum chamber having a diam eter of 400 mm and a height of 400 mm with a microwave launcher and 2.45 GHz microwave generator. The plasma is produced at a pressure of 13 Pa and a total gas flow of 200sccm by a microwave power source. The quadrupole mass spectroscopy and optical emission spectroscopy were used to diagnose the plasma parameters during plasma treatment of microorganisms.