Retinol-Loaded Poly(vinyl alcohol)-Based Hydrogels as Suitable Biomaterials with Antimicrobial Properties for the Proliferation of Mesenchymal Stem Cells.

Polyvinyl alcohol (PVA) hydrogels are well-known biomimetic 3D systems for mammalian cell cultures to mimic native tissues. Recently, several biomolecules were intended for use in PVA hydrogels to improve their biological properties. However, retinol, an important biomolecule, has not been combined with a PVA hydrogel for culturing bone marrow mesenchymal stem (BMMS) cells. Thus, for the first time, the effect of retinol on the physicochemical, antimicrobial, and cell proliferative properties of a PVA hydrogel was investigated. The ability of protein (3.15 nm) and mineral adsorption (4.8 mg/mL) of a PVA hydrogel was improved by 0.5 wt.% retinol. The antimicrobial effect of hydrogel was more significant in S. aureus (39.3 mm) than in E. coli (14.6 mm), and the effect was improved by increasing the retinol concentration. The BMMS cell proliferation was more upregulated in retinol-loaded PVA hydrogel than in the control at 7 days. We demonstrate that the respective in vitro degradation rate of retinol-loaded PVA hydrogels (RPH) (75-78% degradation) may promote both antibacterial and cellular proliferation. Interestingly, the incorporation of retinol did not affect the cell-loading capacity of PVA hydrogel. Accordingly, the fabricated PVA retinol hydrogel proved its compatibility in a stem cell culture and could be a potential biomaterial for tissue regeneration.

Persistent organic pollutants: The trade-off between potential risks and sustainable remediation methods.

Persistent Organic Pollutants (POPs) have become a very serious issue for the environment because of their toxicity, resistance to conventional degradation mechanisms, and capacity to bioconcentrate, bioaccumulate and biomagnify. In this review article, the safety, regulatory, and remediation aspects of POPs including aromatic, chlorinated, pesticides, brominated, and fluorinated compounds, are discussed. Industrial and agricultural activities are identified as the main sources of these harmful chemicals, which are released to air, soil and water, impacting on social and economic development of society at a global scale. The main types of POPs are presented, illustrating their effects on wildlife and human beings, as well as the ways in which they contaminate the food chain. Some of the most promising and innovative technologies developed for the removal of POPs from water are discussed, contrasting their advantages and disadvantages with those of more conventional treatment processes. The promising methods presented in this work include bioremediation, advanced oxidation, ionizing radiation, and nanotechnology. Finally, some alternatives to define more efficient approaches to overcome the impacts that POPs cause in the hydric sources are pointed out. These alternatives include the formulation of policies, regulations and custom-made legislation for controlling the use of these pollutants.

Opportunities and Challenges in the Application of Bioplastics: Perspectives from Formulation, Processing, and Performance.

Tremendously negative effects have been generated in recent decades by the continuously increasing production of conventional plastics and the inadequate management of their waste products. This demands the production of materials within a circular economy, easy to recycle and to biodegrade, minimizing the environmental impact and increasing cost competitiveness. Bioplastics represent a sustainable alternative in this scenario. However, the replacement of plastics must be addressed considering several aspects along their lifecycle, from bioplastic processing to the final application of the product. In this review, the effects of using different additives, biomass sources, and processing techniques on the mechanical and thermal behavior, as well as on the biodegradability, of bioplastics is discussed. The importance of using bioplasticizers is highlighted, besides studying the role of surfactants, compatibilizers, cross-linkers, coupling agents, and chain extenders. Cellulose, lignin, starch, chitosan, and composites are analyzed as part of the non-synthetic bioplastics considered. Throughout the study, the emphasis is on the use of well-established manufacturing processes, such as extrusion, injection, compression, or blow molding, since these are the ones that satisfy the quality, productivity, and cost requirements for large-scale industrial production. Particular attention is also given to fused deposition modeling, since this additive manufacturing technique is nowadays not only used for making prototypes, but it is being integrated into the development of parts for a wide variety of biomedical and industrial applications. Finally, recyclability and the commercial requirements for bioplastics are discussed, and some future perspectives and challenges for the development of bio-based plastics are discussed, with the conclusion that technological innovations, economic incentives, and policy changes could be coupled with individually driven solutions to mitigate the negative environmental impacts associated with conventional plastics.