Polarization Raman study of protein ordering by controllable RBC deformation

Polarized Raman spectroscopy is used to provide evidence of hemoglobin protein ordering as the red blood cell (RBC) is stretched with optical tweezers. The stretching of the cell is intended to mimic the deformation that it experiences as it travels through vessels and capillaries. The depolarization ratios for a number of heme Raman bands change as the cell is stretched, confirming the semi‐ordered nature of the hemoglobin ensemble in the cytoplasm. Furthermore, trends observed in the ratio shifts point to increased packing and ordering of the Hb after cell stretching. This evidence should shed more light on to the role of deformation in the RBC function. Copyright © 2009 John Wiley & Sons, Ltd.     

QCD instantons and the soft pomeron

We study the rôle of semiclassical QCD vacuum solutions in high-energy scattering by considering the instanton contribution to hadronic cross sections. We propose a new type of instanton-induced interactions (“instanton ladder”) that leads to the rising with energy cross section σs^Δ of Regge type (the pomeron). We argue that this interaction may be responsible for the structure of the soft pomeron. The intercept Δ>0 is calculated. It has a nonanalytic dependence on the strong coupling constant, allowing a nonsingular continuation into the nonperturbative region. We derive the pomeron trajectory, which appears to be approximately linear in some range of (negative) momentum transfer t, but exhibits a curvature at small t. Possible rôle of instantons in multiparticle production is also discussed.     

Conditional Singlet Oxygen Generation through a Bioorthogonal DNA‐targeted Tetrazine Reaction

We report the use of bioorthogonal reactions as an original strategy in photodynamic therapy to achieve conditional phototoxicity and specific subcellular localization simultaneously. Our novel halogenated BODIPY‐tetrazine probes only become efficient photosensitizers (Φ_Δ≈0.50) through an intracellular inverse‐electron‐demand Diels–Alder reaction with a suitable dienophile. Ab initio computations reveal an activation‐dependent change in decay channels that controls ¹O₂ generation. Our bioorthogonal approach also enables spatial control. As a proof‐of‐concept, we demonstrate the feasibility of the selective activation of our dormant photosensitizer in cellular nuclei, causing cancer cell death upon irradiation. Thus, our dual biorthogonal, activatable photosensitizers open new venues to combat current limitations of photodynamic therapy.     

1‐(2,4,6‐Tri­methyl­phenyl)‐1H‐1,2,3,4‐tetrazole

In the title compound, C₁₀H₁₂N₄, the tetrazole and phenyl rings are planar to within 0.001 (2) and 0.006 (2) Å, respectively. The two rings are not coplanar and have a dihedral angle of 69.07 (9)° between them. Each mol­ecule is connected with two adjacent ones by C—H?N bridges between atoms of tetrazole rings forming chains parallel with the y axis of the unit cell.     

Hierarchical luminescence patterning based on multiscaled self-assembly

This communication describes a procedure for fabrication of hierarchical luminescence patterns based on the template-assisted assembly of CdSe nanocrystals on a self-assembled structure with green-emitting microstripes, as well as the photoinduced fluorescence enhancement of CdSe nanocrystals and photobleaching of dyes. The technique is low-cost and high-throughput and can be extended to many material combinations.