Improved biocompatability of silicone rubber by removal of surface entrapped air nuclei

Abstract

Biomaterials activate the complement system which is important since C3a promotes platelet aggregation and release, and C5a activates neutrophils that may augment coagulation. Tiny air nuclei (microbubbles) are found in the surface roughness of biomaterials on exposure to a liquid, therefore two interfaces exist: (a) a blood/biomaterial, and (b) a blood/air interface. Experiments were carried out that documented that air bubbles activate complement and augment in vitro platelet aggregation in human plasma. The air nuclei were removed from the surface of silicone rubber by a technique termed denucleation to determine if complement activation and platelet aggregation could be reduced. We observed a significant reduction in C3a and C5a in the plasma samples incubated with denucleated silicone rubber as compared to the control samples (p less than 0.001, ANOVA). The plasma incubated with the denucleated silicone caused reduced platelet aggregation as compared to the plasma incubated with the control silicone when added to a platelet suspension (p less than 0.001, ANOVA). Surface chemical analysis by x-ray photo-electron spectroscopy (XPS) showed no change in the silicone rubber surface after the denucleation procedure.

Biostability and macrophage‐mediated foreign body reaction of silicone‐modified polyurethanes

“…Previously, we reported oxidative mechanisms of polycarbonate soft segment and hard segment chain scission. 19 These results correlated well with the findings of that study and supported the hypothesis that oxidation is the dominant mechanism of surface degradation of PCUs. The silicone modification did not inhibit oxidative chain scission and crosslinking of PEU-S and PCU-S.…”

“…PDMS film specimens were extracted overnight with two changes of hexane to remove silicone oil residues after vulcanization. Before cell culture, air bubbles were removed from the PDMS surfaces using the method previously described by Kalman et al 19 …”

Modification of polysiloxane polymers for biomedical applications: a review

“…From the clinical point of view, compatibility of a biomaterial ideally requires: (a) the absence of thrombogenic, toxic, allergic or inflammatory reactions; (b) no destruction of formed elements; (c) no change in plasma proteins or enzymes; (d) no immunological reactions; (e) no carcinogenic effects; and (f) no deterioration of adjacent tissues 9. Although silicone rubber has mostly been used as soft tissue because of its excellent softness, stability and bioinertness, some problems have occurred when the silicone devices were implanted for a long time 10–13…”

Red blood cell and platelet interactions with titanium implant surfaces

“…Second, we mimicked clinical blood/implant interactions by employing static and air-contacting, rather than flow and air-exclusion conditions. It should be noted that the majority of the blood/ material interactions literature focuses on the thrombogenic potential of candidate vascular replacement materials in models of physiological blood flow conditions (Haycox & Ratner 1993;Nan et al 1998;Park et al 1986;Zhang et al 1998;Jirouskova et al 1997;Rubens et al 1995) and thus, great emphasis has been given to the elimination of the air/biomaterial interface (Warren et al 1973;Thorsen et al 1993;Jian et al 1996;Kalman et al 1991). However, in the case of endosseous implants, and particularly that of dental implants, implants that have been exposed to air come into contact with blood that has been pooled at the surgical site.…”