No abstract

Postsurgical infection of orthopedic fixation materials is considered to be the main cause of fixation failure. To address the problem, clinical treatment often relies on long-term antibiotics, secondary surgery, and so forth, which cause pain and suffering to patients. Constructing a light-responsive surface structure on the implant has attracted widespread attention for the management of postsurgical infections because of its noninvasiveness and controllability. Nevertheless, the application of light-responsive structures on implants is still limited by their unsafety and instability. In this work, a black titanium oxide layer with a multilevel structure and lattice defects was in situ constructed on a titanium alloy through pulsed laser ablation treatment. Under the synergistic effect of the multilevel structure and crystal defects, the surface of the titanium alloy exhibited good near-infrared light-responsive photothermal ability. The black titanium oxide multilevel structure reached high antibacterial efficiencies of about 99.37 and 99.29% against Staphylococcus aureus and Escherichia coli under 10 min near-infrared light irradiation. Furthermore, the black titanium oxide layer possessed similar biocompatibility compared with the titanium alloy. This near-infrared light-responsive photothermal therapy based on the construction of a multilevel structure and introduction of lattice defects provides an effective strategy for clinical postsurgical infections of orthopedic fixation.

Triple-negative breast cancer (TNBC) is an aggressive BC subtype with a higher metastatic rate and a worse 5-year survival ratio than the other BC. It is an urgent need to develop a noninvasive treatment with high efficiency to resist TNBC cell proliferation and invasion. Internal wireless electric stimulation (ES) based on piezoelectric materials is an emerging noninvasive strategy, with adjustable ES intensity and excellent biosafety. In this study, three different barium titanate nanoparticles (BTNPs) with different crystal phases and piezoelectric properties were studied. Varying intensities of internal ES were generated from the three BTNPs (i.e., BTO, U-BTO, P-BTO). In vitro tests revealed that the internal ES from BTNPs was efficient at reducing the proliferative potential of cancer cells, particularly BC cells. In vitro experiments on MDA-MB-231, a typical TNBC cell line, further revealed that the internal wireless ES from BTNPs significantly inhibited cell growth and migration up to about 82% and 60%, respectively. In vivo evaluation of MDA-MB-231 tumor-bearing mice indicated that internal ES not only resisted almost 70% tumor growth but also significantly inhibited lung metastasis. More importantly, in vitro and in vivo studies demonstrated a favorable correlation between the anticancer impact and the intensities of ES. The underlying mechanism of MDA-MB-231 cell proliferation and metastasis inhibition caused by internal ES was also investigated. In summary, our results revealed the effect and mechanism of internal ES from piezoelectric nanoparticles on TNBC cell proliferation and migration regulation and proposed a promising noninvasive therapeutic strategy for TNBC with minimal side effects while exhibiting good therapeutic efficiency.