Biological evaluation of acellular bovine bone matrix treated with NaOH.

We mainly proceed from the view of biological effect to study the acellular bovine bone matrix (ABBM) by the low concentration of hydrogen oxidation. After cleaning the bovine bone routinely, it was cleaned with different concentrations of NaOH and stained with hematoxylin-eosin (HE) to observe the effect of decellulization. The effect of bovine bone matrix treated with NaOH were observed by optical microscopy and scanning electron microscopy (SEM), and compared by DNA residue detection. Cell toxicity was also evaluated in MC3T3-E1 cells by CCK-8. For the in vitro osteogenesis detection, alkaline phosphatase (ALP) staining and alizarin red (AR) staining were performed in MC3T3-E1 cells. And the in vivo experiment, Micro CT, HE and Masson staining were used to observe whether the osteogenic effect of the materials treated with 1% NaOH solution was affected at 6 and 12 weeks. After the bovine bone was decellularized with different concentrations of NaOH solution, HE staining showed that ultrasonic cleaning with 1% NaOH solution for 30 min had the best effect of decellularization. The SEM showed that ABBM treated with 1% NaOH solution had few residual cells on the surface of the three-dimensional porous compared to ABBM treated with conventional chemical reagents. DNA residues and cytotoxicity of ABBM treated with 1% NaOH were both reduced. The results of ALP staining and AR staining showed that ABBM treated with 1% NaOH solution had no effect on the osteogenesis effect. The results of micro-CT, HE staining and Masson staining in animal experiments also showed that ABBM treated with 1% NaOH solution had no effect on the osteogenesis ability. The decellularization treatment of ABBM with the low concentration of NaOH can be more cost-effective, effectively remove the residual cellular components, without affecting the osteogenic ability. Our work may provide a novelty thought and a modified method to applicate the acellular bovine bone matrix clinically better. Graphical abstract.

A healing promoting wound dressing with tailor-made antibacterial potency employing piezocatalytic processes in multi-functional nanocomposites.

Developing a novel antibiotics-free antibacterial strategy is essential for minimizing bacterial resistance. Materials that not only kill bacteria but also promote tissue healing are especially challenging to achieve. Inspired by chemical conversion processes in living organisms, we develop a piezoelectrically active antibacterial device that converts ambient O2 and H2O to ROS by piezocatalytic processes. The device is achieved by mounting nanoscopic polypyrrole/carbon nanotube catalyst multilayers onto piezoelectric-dielectric films. Under stimuli by a hand-held massage device, the sterilizing rates for S. aureus and E. coli reach 84.11% and 94.85% after 10 minutes of operation, respectively. The antibacterial substrate at the same time preserves and releases drugs and presents negligible cytotoxicity. Animal experiments demonstrate that daily treatment for 10 minutes using the device effectively accelerates the healing of infected wounds on the backs of mice, promoting hair follicle generation and collagen deposition. We believe that this report provides a novel design approach for antibacterial strategies in medical treatment.

Biofriendly molecular and protein release substrate with integrated piezoelectric motivation and anti-oxidative stress capabilities.

Self-powered piezoelectrically active molecular or protein delivery devices have provoked great interest in recent years. However, electric fields used to promote delivery or healing may also induce the redox of water or oxygen to generate reactive oxygen species (ROS) and bring unintended oxidative pressure to the organism and harm biological functions. In addition, protein molecules are easily inactivated in the polymer reservoir matrix due to the pull of strong electrostatic effects. In this study, a multifunctional molecular delivery substrate was fabricated by integrating a piezoelectric-dielectric polymeric substrate, nanoscopic polyelectrolyte films and in-film deposited biomimetic porous CaP coating. The piezoelectric substrate promoted molecular release, and the mineralized coating effectively stored molecules or proteins and simultaneously eliminated ROS, reducing the oxidative stress response generated by oxidative pressure. The present work opens a new way for the development of multifunctional and biofriendly drug delivery devices.