Event Abstract Back to Event Atmospheric-pressure and low-pressure plasma amination of stent alloy for bioactive protein immobilization Charlotte Rasser1, 2*, Pascale Chevallier3*, Frédéric Chaubet2*, Caroline Jobin1, 2, Diego Mantovani3*, Michael Tatoulian1, Giuseppina Caligiuri2* and Cédric Guyon1* 1 Institut de Recherche de Chimie Paris, Laboratory 2PM, France 2 Laboratory for Vascular Translational Science - Inserm U1148, France 3 Laval University, Laboratory for Biomaterials and Bioengineering, Canada Introduction: Percutaneous implantation of metallic arterial stents is a keystone in the treatment of coronary artery stenosis. Although relatively modest (8-10%), the 4-year mortality associated with the use of arterial stents is a significant medical concern, because the use of these technologies is widespread. The life-threatening complications associated with the use of coronary stents are thrombosis and restenosis [1],[2]. They are linked to the reaction of the blood/vessel interface to the exogenous material. To avoid this reaction, we aim at coating the stent alloy with a biomimetic protein, able to stimulate fast endothelialization while preventing leukocytes and platelets activation. Direct grafting of such agent on the alloy (L-605 CoCr) can be performed by plasma amination of the surface, followed by covalent bonding of the peptide using a carbodiimide. The objective of this work was to set up a suitable plasma amination protocol. Materials and Methods: Plasma amination was carried out either by ICP-RF low-pressure (LP) plasma (Plasmionique’s FLR-300) or by atmospheric-pressure (AP) cold plasma jet (Acxys’ ULS). N2 and H2 were used as plasma gas (total flow: 100 sccm in LP plasma, 35 L/min in AP plasma). A plasma pre-treatment was applied in some cases, with Ar and O2 as plasma gas (25 sccm Ar, 25 sccm O2). XPS analyses were performed on a PHI 5600-ci spectrophotometer (Physical Electronics), with a standard Al anode. Figure 1. Atomic percentages obtained from XPS survey of L-605 CoCr samples treated by atmospheric-pressure plasma. Plasma gas: 97% N2, 3% H2, total flow 40L/min. Plasma source frequency: 200 kHz. Power: 600 W. Figure 2. Atomic percentages obtained from XPS survey of L-605 CoCr samples treated by low-pressure plasma. Pre-treatment: Ar-O2 plasma, 25-25 sccm, 5 min, 100 W, 4 Pa. Treatment: N2-H2 plasma, total flow 100 sccm, 20 min, 100 W, 40 Pa. Results and Discussion: Figure 1 shows the atomic percentages of C, O and N obtained from the XPS survey of AP plasma-treated samples. The influence of the speed and number of sweeps of the plasma torch over the surface was studied. Maximum nitrogen content (2.7%) is achieved with 4 sweeps of the plasma torch, at 300 mm/s. Figure 2 shows the influence of pre-treatment and N2-H2 mix composition on the quantity of nitrogen deposited on plasma-treated samples. The amount of grafted nitrogen increases with hydrogen content of the gas mix. This effect can be explained by hydrogen promoting the formation of reactive NH species in the plasma. Higher nitrogen surface atomic percentage is achieved without Ar-O2 plasma pre-treatment. By eliminating part of the carbon species on the surface of the samples, pre-treatment might reduce the efficacy of nitrogen species grafting. The maximum nitrogen surface atomic percentage achieved (5.5%) can be highly sufficient for ensuring good covering of the surface by peptide grafting – if a significant part of the deposited nitrogen is in the form of primary or secondary amines. This will be later determined by chemical derivation. Conclusion: Optimization of LP and AP plasma amination of CoCr samples was performed. Both plasma methods achieved significant nitrogen grafting, thus making it possible to proceed to the next steps of the project: quantification of grafted amines by chemical derivation and covalent bonding of proteins to the amines. Thus, a new step towards direct grafting of bioactive peptide on stent surface has been realised.