Although the rational designed mechanochromic polymer (MCP) materials have evoked major interest and experienced significant progress recently, it is still a great challenge to develop a facile and effective strategy for preparation of reversible broad-spectrum MCPs with a combination of wide-range color switch ability and high sensitivity, which thus make it possible to mimic gorgeous color change as in nature. Herein, we designed and synthesized a novel rhodamine-based mechanochromic elastomer. Our results demonstrated that the elastomer exhibited very promising and unique properties. Three primary fluorescence colors were presented during continuous uniaxial extension and relaxing process, and reversible broad-spectrum fluorescence color change could be achieved consequently. The fluorescence quantum yield of the opened zwitterion of this new mechanophore was as high as 0.67. In addition, the elastomer showed very high sensitivity to stress with a detectable activation strain of ∼0.24, which was much smaller than those reported in the previous literature reports. Meantime, the easy-to-obtain material, facile preparation, and good mechanical property also made it suitable for potential practical applications.

Polymerization of methyl acrylate under ultraviolet (UV) irradiation in the presence of S-1-dodecyl-S′-(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (DDMAT) was investigated by in situ 1H nuclear magnetic resonance spectroscopy. Effects of light intensity, wavelength, and concentration of DDMAT on the polymerization behaviors were studied in detail. The experimental results demonstrate that the “living” features of the photopolymerization are related to the concentration of DDMAT. “Living”/controlled radical polymerization was successfully achieved with a high concentration of DDMAT. However, with a low concentration of DDMAT, the polymerization proceeded in an uncontrolled manner and produced polymers with high molecular weights and broad polydispersities. Photochemical behavior of DDMAT was studied in detail, and the results showed that the photolysis of DDMAT was reversible at high concentration, whereas contrarily, DDMAT decomposed irreversibly at low concentration. A possible mechanism was proposed for the reversible photolysis of DDMAT at high concentration, which may involve both reversible termination and reversible addition–fragmentation chain transfer approaches.

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The development and/or progression of perihematomal edema (PHE) in patients with acute spontaneous intracerebral hemorrhage (ICH) vary substantially with different individuals. Although hematoma volume is a useful indicator for predicting PHE, its predictive power was not good at the early stage of ICH. Better predictors are urgently needed. In this study, we found that miR-130a was elevated in the serum of ICH patients and was an independent indicator positively associated with PHE volume within the first 3 days after onset. The R (2) was further evaluated when it is used in combination with hematoma mass. Serum miR-130a levels were associated with clinical outcome (National Institute of Health Stroke Scale (NIHSS) scores at day 14 and modified Rankin Scale (mRS) scores at day 90) only in patients with deep hematoma. Moreover, miR-130a was significantly increased in rat serum and perihematomal tissues and was in line with the change in brain edema. MiR-130a inhibitors reduced brain edema, blood-brain barrier (BBB) permeability, and increased neurological deficit scores, and miR-130a mimics increased monolayer permeability. Thrombin-stimulated brain microvascular endothelial cells (BMECs) were a main source of miR-130a under ICH. In the experimental model, the elevated miR-130a level was accompanied by the decreased caveolin-1 and increased matrix metalloproleinase (MMP)-2/9. Meanwhile, caveolin-1 (cav-1) was reduced by miR-130a mimics, accompanied by an increase in MMP-2/9 expression. The upregulated MMP-2/9 was then downregulated by cavtratin, a cav-1 scaffolding domain peptide. This regulation mechanism was authenticated in a thrombin-induced cellular ICH model. Our results suggest that serum miR-130a may serve as a useful early biomarker for monitoring post-ICH PHE and predicting prognosis and may be helpful in the decision-making of individualized therapy.