3D-printed ß-TCP/S53P4 bioactive glass scaffolds coated with tea tree oil: Coating optimization, in vitro bioactivity and antibacterial properties.

Bone infection treatment is a significant challenge for the orthopedic field. 3D printing is a promising technology to produce scaffolds with customized architecture, able to stimulate and support bone growth. ß-TCP and S53P4 bioactive glass (BG) are well-known biomaterials for scaffold manufacturing. However, a multifunctional scaffold, able to inhibit microbial proliferation at the defect site, is of increasing interest to avoid infection recurrence. Tea tree oil (TTO) has aroused interest as an antimicrobial agent to minimize the use of antibiotics. Therefore, combining the regenerative potential of a bioceramic with TTO's antimicrobial properties could result in a scaffold capable of stimulating tissue growth and treating infections. In this context, this study aimed to produce and characterize 3D-printed ß-TCP/S53P4 BG scaffolds coated with TTO. Scaffolds morphological and chemical characterizations were carried out through XDR, SEM, and FTIR analysis. ß-TCP/S53P4 BG scaffolds showed a compressive strength of ~2 MPa and 53 ± 2% of porosity. The scaffolds were coated by two different procedures, using an ethanol/TTO (EtOH/TTO) and a gelatin/TTO (Gel/TTO) solution with 5, 10, and 15% (v/v) TTO. The addition of TTO decreased MG-63 cell viability for both coating groups, but the Gel/TTO group showed higher cell viability. The antibacterial activity of the coated scaffolds was evaluated against S. aureus and higher inhibition of colony formation was found for Gel/TTO group. Therefore, the coating with Gel/TTO was effective in terms of antibacterial activity and cell viability. Such Gel/TTO coated ß-TCP/S53P4 BG scaffolds are proposed for antibacterial bone tissue engineering.

Aluminum anodizing waste and its uses: An overview of potential applications and market opportunities.

The aluminum anodizing process generates a large volume of waste composed mainly of amorphous aluminum hydroxide with chemical compatibility to be used in other industrial processes as an alternative starting raw material. This waste has several application possibilities such as the production of refractories, ceramic pigments, bricks, and many others. However, despite its potential features, its recycling process is far from well consolidated. This work highlights the most important contributions regarding Al-anodizing waste (AAW) features and their potential applications from the last 30 years. We provide the most complete and detailed characterization of AAW including chemical, physical, thermal, and microstructural analysis. The characterization analyzes were performed in a Brazilian waste sample and were compared with AAW worldwide. Additionally, our characterization results also considered differentiate previous processing; this, it many other possibilities are suggested that have not been explored thus far. The recycling feasibility of AAW is discussed according to the following criteria: classification, including legislation and standards; potentiality, including physical and chemical characteristics and purity; quantity, including production data; viability, including availability, costs regarding disposal and recycling process, and available technology for recycling; and applicability, including market opportunities. Moreover, alumina recovery from AAW and the related environmental aspects are discussed.