Thermal/Redox-triggered release of pyrazinic functional molecules by coordination polymers with luminescence monitoring ability.

Storage of volatile active molecules, along with the prolongation of their specific functions, requires the use of regulatable carriers. Pyrazine derivatives are highly volatile compounds with a broad application owing to their flavoring, pharmaceutical, antimicrobial, antiseptic, and insecticidal properties. In this study, pyrazines were stored by coordinating them with cuprous iodide to easily generate a series of luminescent coordination polymer (CP)-based carriers. The CPs could respond to thermal-redox stimuli and manipulate pyrazine release by breaking the labile Cu-N bonds when triggered by the two stimuli. Moreover, the release process could be visualized by decreased luminescence caused by the gradual decomposition of CP structures. The loading efficiencies ranged from 31% to 38%, and the controlled release behaviors accord with the zero-order kinetics. This work is the first to prove that CPs could function as dual stimuli-mediated delivery systems, which hold the potential to control the release and strengthen the usability of functional molecules.

Influence of the second phase on protein adsorption on biodegradable Mg alloys' surfaces: Comparative experimental and molecular dynamics simulation studies.

The effect of the second phase on the mechanical properties and corrosion resistance of Mg alloys has been systematically studied. However, there is limited information on the effect of the second phase on protein adsorption behavior. In the present study, the effect of the second phase on protein adsorption on the surfaces of biodegradable Mg alloys was investigated using experimental methods and molecular dynamics (MD) simulations. The experimental results showed that the effect of the second phase on fibrinogen adsorption was type-dependent. Fibrinogen preferentially adsorbed on Y-, Ce-, or Nd-involved second phases, while the second phase containing Zn inhibited its adsorption. MD simulations revealed the mechanism of the second phase that influenced protein adsorption in terms of charge distribution, surface-protein interaction energy, and water molecule distribution. Our studies proposed a deep understanding of the design of Mg-based biomaterials with superior biocompatibility. STATEMENT OF SIGNIFICANCE: Mechanical properties, uniform degradation, and biocompatibility must be considered while designing biomedical Mg alloys. To improve the mechanical properties and corrosion resistance of Mg alloys, the second phase is usually required. However, the effects of the second phase on biocompatibility of Mg alloys have been rarely reported. Here, the influence of the second phase on protein adsorption was experimentally studied by designing Mg alloys with different types of second phase. The first principle calculation and MD simulation were used to reveal the mechanism by which the second phase influences protein adsorption. This work could be used to better elucidate the protein adsorption mechanisms and design principles to improve the biocompatibility of Mg alloys.