PhD Thesis Defense by Laura Lefaix, predoctoral researcher at IMB-CNM.
Supervisors:
- Gonzalo Murillo Rodríguez (IMB-CNM)
- Andreu Blanquer Jerez (UAB)
- Carme Nogués Sanmiquel (UAB)
PhD Committee:
- Borja Sepúlveda Martínez
- Tania Patiño Padial
- Massimo de Vittorio
University: Universitat Autònoma de Barcelona
About the thesis
Alternative methods to promote cell stimulation and their subsequent effects, such as cell proliferation and differentiation, are being sought to enhance tissue healing and promote specific tissue functions. The use of devices capable of electrically stimulating cells has gained increasing importance in bioengineering and biomedical applications. Among the explored technologies, piezoelectric materials offer unique physical properties that enable self-powered electrical stimulation from in situ mechanical energy sources such as body motion or inherent cell forces. Furthermore, these materials allow for wireless actuation via externally-applied ultrasound, broadening their potential for minimally-invasive and remote biomedical applications.
In this context, the present thesis explores the fabrication, characterization, and biological application of piezoelectric microdevices for cell stimulation, based on zinc oxide nanosheets (ZnO NSs) grown on custom-fabricated microparticles. First, we developed an innovative approach that combines microfabrication techniques with hydrothermal synthesis to fabricate the proposed microdevices. Second, we investigated the influence of microdevice size on cellular uptake, demonstrating that size can be tuned to prevent internalization, and that Saos-2 cancer cells preferentially internalize the microdevices. The NS dimensions were also optimized to enhance cell stimulation. Third, we examined the mechanisms by which ZnO NSs modulate cellular activity, focusing on calcium signaling and stem cell differentiation. Finally, we evaluated the effect of ultrasound actuation, revealing that the combined application of microdevices and ultrasound significantly increases the number of cells exhibiting calcium transients. These findings demonstrate the potential of ultra-miniaturized, self-powered piezoelectric microdevices for advanced bioelectronic applications and regenerative medicine. Collectively, the results contribute to the development of advanced materials for electrical cell stimulation and broaden the current knowledge in the field.