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Polyetheretherketone (PEEK) is an alternative to metallic implants and a material of choice in many applications, including orthopedic, spinal, trauma, and dental. While titanium (Ti) and Ti-alloys are widely used in many intraosseous implants due to its biocompatibility and ability to osseointegrate, negatives include stiffness which contributes to shear stress, radio-opacity, and Ti-sensitivity. Many surgeons prefer to use PEEK due to its biocompatibility, similar elasticity to bone, and radiolucency, however, due to its inert properties, it fails to fully integrate with bone. Accelerated Neutral Atom Beam (ANAB) technology has been successfully employed to demonstrate enhanced bioactivity of PEEK both in vitro and in vivo . In this study, we further characterize surfaces of PEEK modified by ANAB as well as elucidate attachment and genetic effects of dental pulp stem cells (DPSC) exposed to these surfaces. ANAB modification resulted in decreased contact angle at 72.9 ± 4.5° as compared to 92.4 ± 8.5° for control (p < 0.01) and a decreased average surface roughness, however with a nano-textured surface profile. ANAB treatment also increased the ability of DPSC attachment and proliferation with considerable genetic differences showing earlier progression towards osteogenic differentiation. This surface modification is achieved without adding a coating or changing the chemical composition of the PEEK material. Taken together, we show that ANAB processing of PEEK surface enhances the bioactivity of implantable medical devices without an additive or a coating.

Gas cluster ion beams are proposed as a new tool for producing nanometer sized holes in ultrathin 2D films. Surfaces of films of graphene, graphene oxide, MoS2, and HOPG, and also silicon as a reference, were irradiated by Ar gas cluster ion beams (Exogenesis Corporation, Billerica, MA USA). The results were analyzed using atomic force microscopy (AFM) and Raman spectroscopy. Ar gas cluster ion acceleration energy was 30 keV and total ion fluences ranged from 1×108 to 1×1013 cm-2. Uniformly distributed holes, typically in the range of 10 to 25 nanometers in diameter, produced by the cluster ions, were observed on the surface of graphene oxide. To the best of our knowledge, this is first experimental observation of such holes.

Defect formation in the samples of graphene, graphene oxide and silicon irradiated with Ar cluster and highly-charged ion irradiations were studied. Ar cluster ions, with acceleration energy E = 30 kV (Exogenesis nAccel00, Boston, USA) and total Ar cluster ion fluences ranged from 1x109cm-2to 1x1013cm-2were directed toward various surfaces. Highly-charged ions (HCI) bombardment on surfaces with highly charged Xeq+(q= 22) was employed at Eurasian National University, Kazakhstan, using a DC-60 cyclotron accelerator. Multi-layer graphene oxide, single-layer graphene- (SLG), few-layer of graphene (FLG) and polished Si are used for irradiation experiments. The study of irradiated samples was conducted by Raman spectroscopy, atomic force microscopy (AFM). Uniformly distributed defects and craters were observed on the surfaces of graphene, graphene oxide and silicon irradiated with cluster and HCI beams in our experiments. Ab-initio density-functional theory (DFT) was used to study point defects and molecular-dynamics (MD) simulations were used for studying formation of craters due to gas cluster ion impacts in graphene. The results of simulations were compared with experimental craters and surface shape.

Much discussion has focused on the possible inflammatory and thrombogenic influences of the polymer coating on drug‐eluting stents (DES) and the potential for late stent thrombosis. Biodegradable polymers and/or microporous materials are being evaluated by others. In this study, we have used Argon based GCIB to adhere the drug to the surface of a metal. GCIB bombardment results in surface modification of the top 100Å, allowing a thin coating of drug to adhere to the surface without polymer. Titanium foils cut into 1.5cm2 pieces were initially processed with GCIB at 5x1014 Ar clusters/cm2. 50μg of rapamycin (RAP) was placed on the surface; one group received a GCIB drug surface processing while another group did not. Pieces of foil were placed in plasma at 37oC on a rotator to simulate in vivo drug elution for up to 14 days (n=3). Pre‐ and post‐ eluted foils were then placed in plates and 104 mouse endothelial cells were seeded per foil, allowed to attach for 24 hours, and counts were measured by MTS assay. RAP on foils not receiving the second modification by GCIB eluted off within 24 hours and increased cell attachment from 576±403 cells (pre‐eluted) to 8876±1170 (24h post‐eluted, p<0.01). Foils that received a second GCIB modification caused the RAP to be eluted off more slowly, requiring 72 hours before cell attachment matched no‐drug controls (p<0.05). Therefore, GCIB could replace polymers as a drug delivery method for DES.

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