Surface functionalization via in situ interaction of plasma-generated free radicals with stable precursor-molecules on cellulose

Abstract

The surface functionalization process was

Functionalization of Nonwoven Pet Fabrics by Water/O2 Plasma for Biomolecule Mediated Cell Cultivation

“…Reactive plasma carboxylic functionalization using precursor molecules of the desired functionalities (e.g., acrylic acid or maleic anhydride)26, 27 are even more subject to fragmentation processes in gas (vapors) phase as a result of their interactions with the electrons and with the precursor‐derived, nascent, charged, free radicals, and neutral species; in addition to the desired functionalities, other functional groups will be simultaneously implanted onto the surfaces, reducing the specificity of the functionalization process; free radical sites (reactive surface radicals and stable, “caged” free radicals)8, 9 will initiate after plasma treatment,9, 10 non‐specific interactions with target molecules (e.g., biomolecules), which obviously will diminish significantly the molecular recognition capabilities (specificity) of the modified substrates. Possible solutions for these problems have been reported by using pulsed plasma discharges27–32 or plasma assisted macromolecules grafting 33.…”

“…However, during the plasma ON period of the cycle the fragmentation of precursor molecules can also generate unwanted or difficult to control functionalities, increasing the complexity of interactions with biomolecules for example. A non‐reactive plasma treatment can produce free radicals on the surface of polymers10 that have better chances to generate monofunctional surfaces by chemical reaction with molecule bearing desired functionalities.…”

“…The chamber was then evacuated to the base pressure, and once the pre‐determined pressure was established by the introduction of the water and oxygen at required flow rates, the plasma was ignited and sustained at the desired RF power for the selected treatment time. At the end of the reaction, the system was maintained under lower water flow rate (5 sccm) at 126.65 Pa for 1 h for free radicals quenching 10. The system was evacuated to base pressure, then purged with argon (pressurizing/evacuation cycles), and finally pressurized at 66.66 Pa with oxalyl chloride for 30 min.…”

“…The plasma phase consists of a wide spectrum of very reactive species (electrons, ions, free radicals, metastable, and photons). Plasma exposure of the polymer surface is producing very reactive radicals8 that can be converted to the desired functional groups by chemical reactions9 in situ, in the absence of plasma, with the suitable chemicals 10. Glow discharge (plasma) techniques are particularly useful for the functionalization of surfaces, since they can produce or modify only very thin layers (in the order of 25–100 Å) at the outermost surface of the substrate 11…”

Direct Covalent Biomolecule Immobilization on Plasma-Nanotextured Chemically Stable Substrates

“…Surface groups created by the plasma are usually chemically unstable-in-time (a phenomenon often termed "aging", or hydrophobic recovery for plasma-hydrophilized surfaces), and thus surfaces have to be used immediately after treatment. 17 For this reason, plasma-etched surfaces are less frequently used for biomolecule immobilization, 19−25 compared to plasma polymerized surfaces. 17,26−37 An exception to this rule is the work by Bilek et al, 2,38 who proposed an energetic ion-assisted plasma process (plasma immersion ion implantation) in order to produce surfaces chemically stable for months containing free radicals, which can directly immobilize biomolecules covalently on the surface.…”