Piezoelectric materials as stimulatory biomedical materials and scaffolds for bone repair

The process of bone repair and regeneration requires multiple physiological cues including biochemical, electrical and mechanical - that act together to ensure functional recovery. Myriad materials have been explored as bioactive scaffolds to deliver these cues locally to the damage site, amongst these piezoelectric materials have demonstrated significant potential for tissue engineering and regeneration, especially for bone repair. Piezoelectric materials have been widely explored for power generation and harvesting, structural health monitoring, and use in biomedical devices. They have the ability to deform with physiological movements and consequently deliver electrical stimulation to cells or damaged tissue without the need of an external power source. Bone itself is piezoelectric and the charges/potentials it generates in response to mechanical activity are capable of enhancing bone growth. Piezoelectric materials are capable of stimulating the physiological electrical microenvironment, and can play a vital role to stimulate regeneration and repair. This review gives an overview of the association of piezoelectric effect with bone repair, and focuses on state-of-the-art piezoelectric materials (polymers, ceramics and their composites), the fabrication routes to produce piezoelectric scaffolds, and their application in bone repair. Important characteristics of these materials from the perspective of bone tissue engineering are highlighted. Promising upcoming strategies and new piezoelectric materials for this application are presented. Electrical stimulation/electrical microenvironment are known effect the process of bone regeneration by altering the cellular response and are crucial in maintaining tissue functionality. Piezoelectric materials, owing to their capability of generating charges/potentials in response to mechanical deformations, have displayed great potential for fabricating smart stimulatory scaffolds for bone tissue engineering. The growing interest of the scientific community and compelling results of the published research articles has been the motivation of this review article. This article summarizes the significant progress in the field with a focus on the fabrication aspects of piezoelectric materials. The review of both material and cellular aspects on this topic ensures that this paper appeals to both material scientists and tissue engineers.