Abstract
Lead-free piezoelectric ceramics like K0.5Na0.5NbO3 (KNN) represent an emerging class of biomaterials for medical technology, as they can be used as components in implantable microelectromechanical systems (MEMS) and bioactive scaffolds for tissue stimulation. Such functional materials can act as working components in future in vivo devices, and their addition to current implant designs can greatly improve the biological interaction between host and implant. Despite this, only a few reports have studied the biocompatibility of these materials with living cells. In this work, we investigate the biological response of two different cell lines grown on KNN thin films, and we demonstrate excellent biocompatibility of the KNN films with the cells. Undoped and 0.5 mol % CaTiO3-doped KNN thin films with nanometer-sized roughness were deposited on platinized silicon (SiPt) substrates, and cell proliferation, viability, and morphology of human 161BR fibroblast cells and rat Schwann cells grown on the KNN films and SiPt substrates were investigated and compared to glass control samples. The results show that proliferation rates for the cells grown on the KNN thin films were equally high or higher than those on the glass control samples, and no cytotoxic effect from either the films or the substrate was observed. The work demonstrates that KNN thin films on SiPt substrates are very promising candidates for components in implantable medical devices.
Highlights
Piezoelectric ceramics are utilized in a wide range of electromechanical technologies due to their ability to passively transduce electrical and mechanical signals.[1]
In contrast to electromagnetic systems, piezoelectric components have excellent scaling potential down to the nanometer range, and piezoelectric thin films are of special interest as components in microelectromechanical systems (MEMS).[2−4] Much research has been devoted to develop processing techniques that allow the integration of piezoelectric films on silicon substrates, which makes them compatible with the wide field of complementary metal− oxide−semiconductor (CMOS) technology.[4,5]
Cross sectional SEM micrographs of the KNN and KNN-CaTiO3 thin films prepared from chemical solution deposition (CSD) on SiPt demonstrate that the KNN films were dense, homogeneous, and without cracks, pinholes, or other macroscopic defects (Figure 1)
Summary
Piezoelectric ceramics are utilized in a wide range of electromechanical technologies due to their ability to passively transduce electrical and mechanical signals.[1]. Piezo- and ferroelectric materials hold great potential for biomedical applications as they can be utilized as active scaffolds for tissue engineering and energy harvesters, sensors and actuators for implantable microelectronic systems as well as for biosensing and -patterning.[6−9] Due to the environmental concerns regarding lead-containing piezoceramics like lead zirconate titanate (Pb(Zr,Ti)O3, PZT),[10] lead-free piezoelectric thin films have been extensively researched in the last two decades.[11,12] Among these, ceramic thin films based on potassium sodium niobate (K0.5Na0.5NbO3, KNN) have received much attention due to their good piezoelectric properties and high Curie temperature.[5,13]. In vitro screening assays for cytotoxicity represent as an effective first approximation for biocompatibility.[14,15] Various forms of KNN ceramics have been subjected to in vitro biocompatibility testing, including bulk ceramics,[16−20] powders and powder extracts[21,22] as well as films on sapphire and polyethylene terephthalate substrates.[23,24] In general, KNN ceramics exhibit low acute (24 h)[19,21−23] and subacute (7 d) toxicity,[24] and KNN pellets and films support proliferation and growth of various cell lines on par with controls
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