**15. Aluminium (or aluminum) and ceramics**

tween the fibers of the interface and the middle strata intra- and extracellular silicone drop‐ lets and bulks were observed, representing the location where further pathological processes can take place [205]. It is said by Dr. Sidney Wolfe, director of Public Citizen's Health Research Group, in a statement that: "Public Citizen continues to oppose the FDA's 2006 decision to return silicone breast implants to the market for cosmetic use in women for augmentation. The agency's newer information about the risk of implant-associated lym‐ phoma and the previously known risks are serious enough to warrant advising women

On March 9, 2012 a new silicone breast implant, which joins the two other silicone breast implants on the market - one made by Allergan and the other by Mentor, was approved by the FDA of the United States of America. Recommended monitoring after initially silicone breast implantation is 3 years and then every two years thereafter. In a review Roach and coworkers concern the importance of length and time on physicochemical interactions be‐ tween living tissue and biomaterials that occur on implantation. The review provides de‐ tailed information on material host interactions, dynamic material/cell surface states, surface chemistry and topological roles during the first stage of implant integration, namely protein adsorption. Generally, after the first contact of material with host tissue a state of flux due to protein adsorption, cell adhesion and physical and chemical alteration of the implanted ma‐ terial is followed (Figure 10) [206]. This model can answer many questions concerning the conformational form and bound proteins and therefore has instruction meanings in new im‐

**Figure 10.** Schematic of protein–surface interactions: Chemistry—adsorption onto biotinylated stripes which appear white, whilst adsorption is hindered on square oligoethylene-glycol regions, the white box shows an intentionally bleached area Topography—albumin adsorption onto hydrophilic silica spheres of varying dimensions as a model of

against having these implanted."

134 Advances in Biomaterials Science and Biomedical Applications

plantable biomaterial design field.

surface curvature [206].

Aluminium (or aluminum) is the third most abundant chemical element (after oxygen and silicon in the boron group) with symbol Al and atomic number 13. It is one of the typical metals which has been widely used as hard tissue repair materials with unique properties, such as strong mechanical strength, not soluble and degradable in body fluid under normal circumstances, combined in over 270 different minerals, low density (weight) and corrosion resistances [211]. It is generally accepted that metallic implant materials with higher strength/modulus ratios are more favorable for hard tissue repair due to a combined effect of high strength and reduced stress-shielding risk [212].

Al alloys, such as Al-silicon (Si), Al-platinum, and Al-titanium (Ti) are widely used in im‐ plantable engineering structures and components where light weight or corrosion resistance is required except for blood-contacting surfaces [213,214]. For example, an implantable dou‐ ble-sided electrode microdevices, called flexible nerve plates, with a prototype of Al layer could reduce the number of insertion sites and thereby the insertion trauma during implan‐ tation of neural prostheses [215]. A Ti-6Al-4vanadium (V) alloy was selected as the ceramicto-metal seal because its excellent mechanical properties and favorable biocompatibility [216]. The first-generation of implantable left ventricular assist devices (LVADs) were Ti-Alvanadium alloy pulsatile, volume-displacement pumps. The modern LVAD era began with the introduction of the HeartMate X (vented electric) VE in 1998 [217]. These devices can provide excellent circulatory support and improve survival until heart transplantation. However, they have many application limitations, such as a large volume, an excessive sur‐ gical dissection, a large diameter driveline, a noisy pump operation, and particularly a limit‐ ed mechanical durability. Other complications include bleeding, infections and thromboembolic events. During the succeeding decade, vast improvements in pump design resulted in a new crop of LVADs, whose attributes are transforming LVAD therapy into a kind of standard of care for end-stage heart failure [218]. LVAD therapy has now evolved into a solution which is strikingly superior to optimal medical therapy [219, 220].

It was reported that changes in the porous hydroxyapatite and Al oxide orbital implant den‐ sities may correspond to healing and maturation of soft tissues surrounding and penetrating the implants [221]. The thermal oxidation behavior of Al ion implanted Ti nitride films has been studied in dry oxygen atmosphere and found that Al implantation caused the oxida‐ tion rate of TiN films to slow down at the initial stage of oxidation [222]. Until recently, there is limited evidence regarding comparative effectiveness of various hip implant bear‐ ings, especially metal on metal or ceramic on ceramic implants compared with traditional metal on polyethylene or ceramic on polyethylene bearings [223].

For clinical applications, it is an important character that the metal devices do not cause mental or body uncomfortable reactions, such as delaminate or infiltrate ions to the sur‐ round tissues. For example, a defibrillator is a medical device that generates and delivers a shock to the heart of someone in cardiac arrest. Although this device can save lives, there are risks involved, for both the patient and the first responders. One risk associated with defib‐ rillator use is that of burns. Certain transdermal medication patches contain aluminum back‐ ings, and when they come in contact with the defibrillator paddle, can cause minor burns to the patient. Accidental shocks to others can occur when first responders accidentally contact with the patient who is being defibrillated. The only objects that should touch the patient during treatment are the defibrillator paddles held by the administrator of the procedure. Sometimes internally implanted defibrillators discharge shocks when they are unnecessary. When this occurs, it can cause pain and promote a dangerous heart rhythm. In addition, the event can be emotionally disturbing and frightening. Doctor can recalibrate the device to minimize the risk of additional unnecessary shocks, and offer suggestions on how to man‐ age these rare events [224].

A ceramic is an inorganic, nonmetallic solid material possessing strong mechanical proper‐ ties prepared by the action of heat and subsequent cooling [30]. The uses of ceramics have been revolutionizing the biomedical field in deployment as implants for humans during the past three decades. In the search to improve the biocompatibility and mechanical strength of skeletal implant materials, attention has been directed towards the potential use of ceramic composites [225]. Since 1975 alumina ceramic has proven its bioinertness and have been ac‐ cepted in biomedical applications, some alumina ceramic, such as Al2O3 has been character‐ ized with high hardness and high abrasion resistance. Noiri and coworkers evaluated the biocompatibility of alumina-ceramic material histopathalogically for eight weeks by im‐ planting in the eye sockets of albino rabbits with no signs of implant rejection or prolapse of the implanted pieces. After a period of four weeks of implantation, fibroblast proliferation and vascular invasion were noted. By the eighth week, tissue growth was observed in the pores of the implants [226].

vanadium alloy pulsatile, volume-displacement pumps. The modern LVAD era began with the introduction of the HeartMate X (vented electric) VE in 1998 [217]. These devices can provide excellent circulatory support and improve survival until heart transplantation. However, they have many application limitations, such as a large volume, an excessive sur‐ gical dissection, a large diameter driveline, a noisy pump operation, and particularly a limit‐ ed mechanical durability. Other complications include bleeding, infections and thromboembolic events. During the succeeding decade, vast improvements in pump design resulted in a new crop of LVADs, whose attributes are transforming LVAD therapy into a kind of standard of care for end-stage heart failure [218]. LVAD therapy has now evolved

It was reported that changes in the porous hydroxyapatite and Al oxide orbital implant den‐ sities may correspond to healing and maturation of soft tissues surrounding and penetrating the implants [221]. The thermal oxidation behavior of Al ion implanted Ti nitride films has been studied in dry oxygen atmosphere and found that Al implantation caused the oxida‐ tion rate of TiN films to slow down at the initial stage of oxidation [222]. Until recently, there is limited evidence regarding comparative effectiveness of various hip implant bear‐ ings, especially metal on metal or ceramic on ceramic implants compared with traditional

For clinical applications, it is an important character that the metal devices do not cause mental or body uncomfortable reactions, such as delaminate or infiltrate ions to the sur‐ round tissues. For example, a defibrillator is a medical device that generates and delivers a shock to the heart of someone in cardiac arrest. Although this device can save lives, there are risks involved, for both the patient and the first responders. One risk associated with defib‐ rillator use is that of burns. Certain transdermal medication patches contain aluminum back‐ ings, and when they come in contact with the defibrillator paddle, can cause minor burns to the patient. Accidental shocks to others can occur when first responders accidentally contact with the patient who is being defibrillated. The only objects that should touch the patient during treatment are the defibrillator paddles held by the administrator of the procedure. Sometimes internally implanted defibrillators discharge shocks when they are unnecessary. When this occurs, it can cause pain and promote a dangerous heart rhythm. In addition, the event can be emotionally disturbing and frightening. Doctor can recalibrate the device to minimize the risk of additional unnecessary shocks, and offer suggestions on how to man‐

A ceramic is an inorganic, nonmetallic solid material possessing strong mechanical proper‐ ties prepared by the action of heat and subsequent cooling [30]. The uses of ceramics have been revolutionizing the biomedical field in deployment as implants for humans during the past three decades. In the search to improve the biocompatibility and mechanical strength of skeletal implant materials, attention has been directed towards the potential use of ceramic composites [225]. Since 1975 alumina ceramic has proven its bioinertness and have been ac‐ cepted in biomedical applications, some alumina ceramic, such as Al2O3 has been character‐ ized with high hardness and high abrasion resistance. Noiri and coworkers evaluated the biocompatibility of alumina-ceramic material histopathalogically for eight weeks by im‐

into a solution which is strikingly superior to optimal medical therapy [219, 220].

metal on polyethylene or ceramic on polyethylene bearings [223].

136 Advances in Biomaterials Science and Biomedical Applications

age these rare events [224].

**Figure 11.** Scanning electron microscopy (SEM) images of SaOS-2 cells cultured for 48 h on micropatterned Ti (A-D) and diamond-like carbon (DLC) (E, F) surfaces. Large-sized (125 µm) squared (A) and circular (B) features facilitated the adhesion of several cells on one Ti island with the cells aligning themselves along the edges of the cell-friendly materi‐ al. The cells adhering to mediumsized Ti islands no longer conformed strictly to the geometrical shape of the patterns (C) but particularly on circularly patterned surfaces, star-like cellular morphologies appeared (D). On small-sized in‐ verse DLC samples, the cell bodies non-selectively covered large micro-patterned areas (E), but their filopodia clearly showed a preference for DLC trying to avoid bare Si circles (F) [222].
