Accelerated neutral atom beam(ANAB)and gas clustered ion beam(GCIB)treatment of implantable device polymers leads to decreased bacterial attachment in vitro and decreased inflammation in vivo

Infections at the placement site of biomaterial-based devices and subsequent scar formation results in morbidity,which may require revision surgery.Biomaterials intended for permanent implantation in the body need to be biologically inert to avoid excessive foreign body response and to reduce bacterial attachment.In this study,we show that polymeric materials commonly used in medical devices,including polyetheretherketone(PEEK)and polypropylene,treated by gas cluster ion beam(GCIB)or by accelerated neutral atom beam(ANAB)result in a nanoscale-modified surface topography that changes the ability of extracellular proteins to bind.This leads to decreased bacterial attachment and an attenuated inflammatory response using both in vitro and in vivo assays.Differential adsorption of extracellular proteins to the polymeric surface improved the competitive attachment of osteoblasts over bacteria,without resorting to growth factor of antibiotic use.

Surface bioactivation of PEEK by neutral atom beam technology

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.