(B-49) Modeling of Ultrathin Metal Surface on BaTiO3 Piezoelectric Biomaterial for Antimicrobial Effect

Introduction:: Despite significant progress in biomaterial fabrication, biofilm-related infections remain a challenging problem in modern healthcare [1-3]. Such infections can lead to discomfort, costly surgical interventions, and potentially life-threatening complications. Therefore, the development of infection-resistant biomaterials is crucial for combating these pervasive microbial infections [4]. To this end, we recently reported a BaTiO₃ (BTO) as a potential biomaterial for implantable biomedical devices, such as dental crowns, packaging, etc. [5]. One exciting result was the antimicrobial effect, which exhibited concentration dependent. In this abstract, we reveal a mechanism of the antimicrobial effect using the theory of energy band gap and amplify the antimicrobial effect with the help of ultrathin titanium coating.


Materials and Methods:: First, we experimentally obtained ab-initio properties of BaTiO₃. Almost pure BaTiO₃ composite was created by mixing PVDF/DMF solution (1:9.2 wt%) and BaTiO₃ nanoparticles (500 nm; US Nanomaterial) in a ratio of 97:3 wt%. The mixture was then poured over a mold to cast out a disc-shaped composite. After soft baking at 120°C for 2 hours, the discs were sintered in a furnace. After sintering, the discs were sanded and polished, followed by polishing 2kV/mm at 80°C for 15 minutes. We measured the piezoelectric constant (d-33), Raman, and surface roughness. Based on those material properties obtained from our characterization and material database, we computed the effect of ultrathin layer metal on BaTiO₃. We simulated the band structure by measuring band gaps. For measuring the band gap, we used the Tauc plot equation: (αhν)² = B (hν - Eg), where: α is the absorption coefficient, h is the Planck's constant, ν is the frequency of light, Eg is the bandgap energy, and B is a constant related to the nature of the transition. Fermi level was calculated using E_Fermi= Eg/2, and the work function can be estimated using the following equation: Φ = E_vac - E_Fermi, where, Φ is the work function and E_vac is the energy of the vacuum level.




Results, Conclusions, and Discussions:: Results and Discussion: The piezoelectric coefficient was measured to be 255 pC/N (Quasi Static d-33 meter, PolyK). The crystal structure of our BTO composite was confirmed to be tetragonal (the peak at 299 cm^-1 in Fig. 1(b)) on Raman Spectroscopy (NRS-4500, Jasco). The average surface roughness was 10.5 nm, measured using atomic force microscopy (Fig. 1(c)). To effectively use piezoelectric material, a metal contact is required for poling and electrical connection. It often determines the performance under a certain stress direction. Thus, we hypothesize that an introduction of ultrathin metal (titanium in our case) can amplify the antimicrobial effect on the surface of BTO, which could be explained using the theory of band bending since metal deposition shifts overall work function and electron affinity. Note that band bending is common in metal–semiconductors and metal–ferroelectric interfaces [6]. Fig. 1(d) shows the computed band bending of BTO and titanium interface using MATLAB modeling. We modeled that 5 nm titanium is deposited on a 95 nm thick ferroelectric BTO. We calculated that electron mobility increases due to band bending and thin metal coating by at least 7.69 times [7,8]. The enhanced surface charge is expected to improve the antimicrobial effect significantly.



Conclusions: The study proposed the utilization of an ultrathin titanium layer on BaTiO₃ for antimicrobial effect. Based on experimentally measured ab-initio properties (i.e., d-33, Raman, and AFM), we presented a new approach to amplify the antimicrobial effect using an energy band gap, resulting in improved electron mobility. Overall, the findings suggest that the BaTiO₃ with a thin metal layer has a high potential to bring unique properties.


Acknowledgements (Optional): : This work is supported by National Science Foundation (NSF)(ECCS-2300985).


References (Optional): :

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