It is well known that symmetry plays a key role in chemical reactivity. Here we explore its role in vibrational strong coupling (VSC) for a charge‐transfer (CT) complexation reaction. By studying the trimethylated‐benzene–I2 CT complex, we find that VSC induces large changes in the equilibrium constant KDA of the CT complex, reflecting modifications in the ΔG° value of the reaction. Furthermore, by tuning the microfluidic cavity modes to the different IR vibrations of the trimethylated benzene, ΔG° either increases or decreases depending only on the symmetry of the normal mode that is coupled. This result reveals the critical role of symmetry in VSC and, in turn, provides an explanation for why the magnitude of chemical changes induced by VSC are much greater than the Rabi splitting, that is, the energy perturbation caused by VSC. These findings further confirm that VSC is powerful and versatile tool for the molecular sciences.

Elucidation of the molecular events underlying hepatic stellate cell (HSC) activation is an essential step toward understanding the biological properties of HSC and clarifying the potential roles of HSCs in liver fibrosis and other liver diseases, including hepatocellular carcinoma. Highthroughput comparative proteomic analysis based on isobaric tags for relative and absolute quantitation (iTRAQ) labeling combined with online two-dimensional nanoscale liquid chromatography and tandem mass spectrometry (2D nano-LC-MS/MS) were performed on an in vitro HSC activation model to obtain a comprehensive view of the protein ensembles associated with HSC activation. In total, 2,417 proteins were confidently identified (false discovery rate <1%), of which 2,322 proteins were quantified. Compared with quiescent HSCs, 519 proteins showed significant differences in activated HSCs (!3.0-fold). Bioinformatics analyses using Ingenuity Pathway Analysis revealed that the 319 up-regulated proteins represented multiple cellular functions closely associated with HSC activation, such as extracellular matrix synthesis and proliferation. In addition to the well-known markers for HSC activation, such as a-smooth muscle actin and collagen types 1 and 3, some novel proteins potentially associated with HSC activation were identified, while the 200 down-regulated proteins were primarily related to immune response and lipid metabolism. Most intriguingly, the top biological function, top network, and top canonical pathway of down-regulated proteins were all involved in immune responses. The expression and/or biological function of a set of proteins were properly validated, especially Bcl2-associated athanogene 2, BAG3, and B7H3. Conclusion: The present study provided the most comprehensive proteome profile of rat HSCs and some novel insights into HSC activation, especially the suppressed immune response. (HEPATOLOGY 2012;332-349)

Nonlinear optical responses provide a powerful way to understand the microscopic interactions between laser fields and matter. They are critical for plenty of applications, such as in lasers, integrated photonic circuits, biosensing and medical tools. However, most materials exhibit weak optical nonlinearities or long response times when they interact with intense optical fields. Here, we strongly couple the exciton of cyanine dye J-aggregates to an optical mode of a Fabry-Perot (FP) cavity, and achieve an enhancement of the complex nonlinear refractive index by two orders of magnitude compared with that of the uncoupled condition. Moreover, the coupled system shows an ultrafast response of ~120 fs that we extract from optical cross-correlation measurements. The ultrafast and large enhancement of the optical nonlinar coefficients in this work paves the way for exploring strong coupling effects on various third-order nonlinear optical phenomena and for technological applications.