Natural astaxanthin mainly derives from a microalgae producer, Haematococcus pluvialis. The induction of nitrogen starvation and high light intensity is particularly significant for boosting astaxanthin production. However, the different responses to light intensity and nitrogen starvation needed to be analyzed for biomass growth and astaxanthin accumulation. The results showed that the highest level of astaxanthin production was achieved in nitrogen starvation, and was 1.64 times higher than the control group at 11 days. With regard to the optimization of light intensity utilization, it was at 200 µmo/m 2 /s under nitrogen starvation that the highest astaxanthin productivity per light intensity was achieved. In addition, both high light intensity and a nitrogen source had significant effects on multiple indicators. For example, high light intensity had a greater significant effect than a nitrogen source on biomass dry weight, astaxanthin yield and astaxanthin productivity; in contrast, nitrogen starvation was more beneficial for enhancing astaxanthin content per dry weight biomass. The data indicate that high light intensity synergizes with nitrogen starvation to stimulate the biosynthesis of astaxanthin.
Supramolecular coordination has been developed as an efficient tool to construct a variety of discrete metallacycles and metallacages with well-defined shapes and sizes. However, its application in framework construction has been barely exploited. In this paper, we report the direct synthesis of two diamondoid frameworks from a simple tetrahedral precursor, tetra(4-(4-pyridinyl)phenyl)methane, and two linear difunctional platinum(II) ligands via one-step supramolecular coordination. Controlled by the specific angularity and geometry of the tetrahedral and linear subunits, these frameworks possess a well-defined diamondoid topology with highly regulated periodicity and three-dimensional porosity. Moreover, these rigid frameworks can be directly changed into a metallogel when prepared in DMSO at high concentrations. Interestingly, these diamondoid frameworks exhibit a cationic nature and stimuli-responsive behavior, which potentially endow them with the selective adsorption and controlled release for anionic dyes and drugs in aqueous environments. Thus, this study demonstrates that supramolecular coordination is a facile and efficient approach for the preparation of functional framework materials containing predesigned and well-defined supramolecular coordination assemblies as molecular skeletons.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.