Based on coordination driven co-assembly strategy, metal–organic supramolecular polymers of pyridine Schiff-base cholesterol and silver ion with tunable supramolecular chirality inversion was successfully achieved by the stoichiometry and solvent polarity.

Background Clarifying the molecular mechanism and identifying markers of myocardial ischemia / reperfusion injury is crucial for the treatment of acute myocardial infarction. aims This study aimed to investigate the roles and underlying regulatory mechanisms of microRNA 1283 (miR-1283) and GADD45A in cardiomyocytes injured by hypoxia / reoxygenation (H / R). methods Bioinformatic analyses were used to determine the expression of GADD45A and miR-1283 based on various datasets from the Gene Expression Omnibus database. Human embryonic cardiomyocytes were subjected to H / R to construct in vitro models. Real -time quantitative polymerase chain reaction and Western blot were used to detect mRNA and protein expression levels, respectively. The binding sites between miR-1283 and GADD45A were predicted by the TargetScan software and verified using dual luciferase reporter assays. Cell viability and apoptosis were detected with the use of Cell Counting Kit 8 and flow cytometry assays. results GADD45A and miR-1283 were upregulated or downregulated in myocardial infarction, respectively. MicroRNA 1283 expression was decreased in cardiomyocytes after H / R treatment. H /R treatment reduced cardiomyocyte viability and enhanced apoptosis, and these effects were abated by transfection of a miR-1283 mimic and strengthened by transfection of a miR-1283 inhibitor. MicroRNA 1283 bound to the 3' untranslated region of GADD45A and decreased the levels of GADD45A, which inhibited proliferation and promoted apoptosis in H / R -induced cardiomyocyte injury. Reintroduction of GADD45A attenuated the effect of miR-1283 on the viability and apoptosis of cardiomyocytes in H / R models. The JNK and p38 MAPK signaling pathways were regulated by the miR-283-GADD45A axis. conclusions The miR-1283-GADD45A axis may protect against H / R -induced cardiomyocyte injury by suppressing the JNK and p38 MAPK pathways.

According to extensive studies, the supramolecular chirality of SP and their aggregates is mainly determined by the synergistic effects of the hierarchical transfer of the inherent molecular chirality and the helical stacking of building blocks as well as the pathway during the aggregation process. [2] And the pathway of the aggregation process is mainly dependent on the equivalent and synergy of various non-covalent forces in the whole supramolecular structure. [3] Meanwhile, external stimuli like light, temperature, and solvent can also finely regulate the aggregation pathway in dynamic means. Therefore, both the chemical structures of building blocks and external stimuli play critical roles in the chirality modulation of SP and their hierarchical aggregates, especially for the supramolecular chirality inversion (SMCI). [4] However, despite some satisfactory results reported, it remains a great challenge to finely tailor the circular dichroism (CD) inversion of metal-organic complex-based assemblies with multiple modulations in a dynamic way. [5] To construct a helical self-assembly system with multiple SMCI, two prerequisites of the building block design need to be met: 1) The building block has functional units to sensitively response external stimuli and thereby can be effectively regulated its dynamic assembly; 2) There are multiple supramolecular interaction sites embedded in the molecular building blocks for the fine modulation of helical aggregation with competitive aggregation pathways. The cholesterol unit, as one of natural chiral species, has been extensively studied in the chiral self-assembly systems such as supramolecular gels and liquid crystals. [6] In addition, it can be easily functionalized by covalent synthesis and endows the yielded cholesteryl-conjugated molecules with multiple stimuli responsibility and tunable self-assembly capability in organic solvents/cosolvents from the low-polar solvent of p-xylene (PX) to high-polar solvent of dimethyl sulfoxide (DMSO). [7] On the other hand, the pyridyl unit as another useful functional group is extensively utilized in the supramolecular self-assembly systems because of its good performance such as metal-ion coordination ability, easy form hydrogen bonding, and pH responsiveness. [8] Herein, we synthesize a chiral molecular building block of para-pyridine Schiff-base cholesterol conjugate (pPMPCC). Supramolecular chirality is the inherent property and the corresponding performance of aggregated materials in the supramolecular polymer (SP) system. It is an interesting but challenging issue to regulate the handedness direction of supramolecular chirality and achieve the circular dichroism (CD) inversion of chiral SP-based aggregates, especially for the ones assembled from metalorganic supramolecular polymer (MOSP) with great potential in asymmetric catalysis, chiral recognition, and chiroptical devices. Herein, a set of nanoaggregates coassembled from para-pyridine imine-linked cholesterol conjugate (pPMPCC) and various metal salts, using t...