Dynamic equilibrium unfolding pathway of human tumor necrosis factor-alpha induced by guanidine hydrochloride

AFM-IR probing the influence of polarization on the expression of proteins within single macrophages

Macrophages are essential in innate immunity and are involved in a variety of biological functions. Due to high plasticity, macrophages are polarized in different phenotypes depending on different microenvironments to perform specific functions. Although many studies have focused on macrophage polarization, few have explored the polarization characteristics of macrophages at the subcellular level, even at nanoscale resolution. Here, we utilize AFM-based infrared spectroscopy (AFM-IR) to investigate the influence of an inducer on the expressed proteins of M1/M2 macrophages (induced by LPS and IL-13, respectively). The results from AFM-IR combined with principal component analysis revealed that the characteristic proteins within M1 contain about 35% antiparallel β-sheets (due to the high expression of TNF-α), while the proteins within M2 are made up of approximately 38.8% α-helices. The corresponding nanoscale chemical mapping demonstrates a remarkably heterogeneous distribution of expressed proteins inside single macrophages. Beside the biochemical properties, the biomechanical properties of macrophages were found to be softened in response to the polarization process.

Directly meso-meso linked porphyrin rings: synthesis, characterization, and efficient excitation energy hopping

Directly meso-meso linked porphyrin rings CZ4, CZ6, and CZ8 that respectively comprise four, six, and eight porphyrins have been synthesized in a stepwise manner from a 5,10-diaryl zinc(II) porphyrin building block. Symmetric cyclic structures have been indicated by their very simple (1)H NMR spectra that exhibit only a single set of porphyrin and their absorption spectra that display a characteristic broad nonsplit Soret band around 460 nm. Energy minimized structures calculated at the B3LYP/6-31G* level indicate that a dihedral angle between neighboring porphyrins decreases in order of CZ6 > CZ8 > CZ4, which is consistent with the (1)H NMR data. Photophysical properties of these molecules have been examined by the steady-state absorption, fluorescence, fluorescence lifetime, fluorescence anisotropy decay, and transient absorption measurements. Both the pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related with the excitation energy migration processes within the porphyrin rings, where the exciton-exciton annihilation time and the polarization anisotropy rise time are well described in terms of the Forster-type incoherent energy hopping model. Consequently, the excitation energy hopping rates have been estimated for CZ4 (119 +/- 2 fs)(-)(1), CZ6 (342 +/- 59 fs)(-)(1), and CZ8 (236 +/- 31 fs)(-)(1), which reflect the magnitude of the electronic coupling between the neighboring porphyrins. Overall, these porphyrin rings serve as a well-defined wheel-shaped light harvesting antenna model in light of very efficient excitation energy hopping along the ring.