Carbohydrate arrays fabricated on gold films were used to study carbohydrate-protein interactions with surface plasmon resonance (SPR) imaging. An immobilization scheme consisting of the formation of a surface disulfide bond was used to attach thiol-modified carbohydrates onto gold films and to fabricate carbohydrate arrays. The carbohydrate attachment steps were characterized using polarization modulation Fourier transform infrared reflection absorption spectroscopy; and poly(dimethylsiloxane) microchannels were used to immobilize probe compounds at discrete locations on a gold film. The binding of the carbohydrate-binding proteins concanavalin A (ConA) and jacalin to arrays composed of the monosaccharides mannose and galactose was monitored with SPR imaging. SPR imaging measurements were employed to accomplish the following: (i) construct adsorption isotherms for the interactions of ConA and jacalin to the carbohydrate surfaces, (ii) monitor protein binding to surfaces presenting different compositions of the immobilized carbohydrates, and (iii) measure the solution equilibrium dissociation constants for ConA and jacalin toward mannose and galactose, respectively. Adsorption coefficients (K(ADS)) of 2.2 +/- 0.8 x 10(7) M(-)(1) and 5.6 +/- 1.7 x 10(6) M(-)(1) were obtained for jacalin adsorbing to a galactose surface and ConA adsorbing to a mannose surface, respectively. The solution equilibrium dissociation (K(D)) constant for the interaction of jacalin and galactose was found to be 16 +/- 5 microM, and for ConA and mannose was found to be 200 +/- 50 microM.

Organometallic halide perovskites CH 3 NH 3 PbX 3 (X = I, Br, Cl) have quickly become one of the most promising semiconductors for solar cells, with photovoltaics made of these materials reaching power conversion efficiencies of near 20%. Improving our ability to harness the full potential of organometal halide perovskites will require more controllable syntheses that permit a detailed understanding of their fundamental chemistry and photophysics. In this manuscript, we systematically synthesize CH 3 NH 3 PbX 3 (X = I, Br) nanocrystals with different morphologies (dots, rods, plates or sheets) by using different solvents and capping ligands. CH3NH3PbX3 nanowires and nanorods capped with octylammonium halides show relatively higher photoluminescence (PL) quantum yields and long PL lifetimes. CH3NH3PbI3 nanowires monitored at the single particle level show shape-correlated PL emission across whole particles, with little photobleaching observed and very few off periods. This work highlights the potential of low-dimensional organometal halide perovskite semiconductors in constructing new porous and nanostructured solar cell architectures, as well as in applying these materials to other fields such as light-emitting devices and single particle imaging and tracking.Keywords organometal halide perovskites, nanocrystals, preferred orientation, morphology control, size control, single particle photoluminescence Disciplines Chemistry CommentsReprinted (adapted) with permission from ACS Nano 9 (2015) 15,16 respectively, as well as high absorption coefficients. Critically, organolead perovskites have very long electronÀ hole carrier diffusion lengths, exceeding 1 μm in CH 3 NH 3 PbI 3-x Cl x , and 100 nm in CH 3 NH 3 PbI 3 , which in principle allows for the development of several solar cell architectures including perovskite-sensitized solar cells, planar heterojunction solar cells, and meso-and nanostructured solar cells. 17 Building on the dramatic improvement of solar cell performance using the solid hole conductor spiro-OMeTAD instead of a liquid electrolyte (spiro-OMeTAD stands for 2,2 0 -7,7 0 -tetrakis(N,N-di-p-methoxy-phenylamine)-9,9 0 -spirobifluorene), 18 the energy conversion efficiency of photovoltaics made from these intensely absorbing, visible-active semiconductors has risen from 3.8% to near 20% in only four years. 19,20 Photovoltaic performance depends critically on perovskite composition, crystallinity and morphology. 21À23 Higher perovskite film uniformity leads to lower recombination rates in planar heterojuction solar cells. 24,25 Film uniformity is affected by factors such as precursor composition, annealing temperature and, if applicable, solvent used during the vapor-assisted or spin coating deposition process. 6,24,26À32 Highly efficient mesostructured solar cells are produced by a twostep deposition process. 33À35 Vapor-assisted methods and additives provide the means * Address correspondence to jwp@iastate.edu, esmith1@iastate.edu, vela@iastate.edu.Received for review December 9, 2014 a...

Photocages are light-sensitive chemical protecting groups that provide external control over when, where, and how much of a biological substrate is activated in cells using targeted light irradiation. Regrettably, most popular photocages (e.g., o-nitrobenzyl groups) absorb cell-damaging ultraviolet wavelengths. A challenge with achieving longer wavelength bond-breaking photochemistry is that long-wavelength-absorbing chromophores have shorter excited-state lifetimes and diminished excited-state energies. However, here we report the synthesis of a family of BODIPY-derived photocages with tunable absorptions across the visible/near-infrared that release chemical cargo under irradiation. Derivatives with appended styryl groups feature absorptions above 700 nm, yielding photocages cleaved with the highest known wavelengths of light via a direct single-photon-release mechanism. Photorelease with red light is demonstrated in living HeLa cells, Drosophila S2 cells, and bovine GM07373 cells upon ∼5 min irradiation. No cytotoxicity is observed at 20 μM photocage concentration using the trypan blue exclusion assay. Improved B-alkylated derivatives feature improved quantum efficiencies of photorelease ∼20-fold larger, on par with the popular o-nitrobenzyl photocages (εΦ = 50-100 M cm), but absorbing red/near-IR light in the biological window instead of UV light.

Photoremovable protecting groups derived from meso-substituted BODIPY dyes release acetic acid with green wavelengths >500 nm. Photorelease is demonstrated in cultured S2 cells. The photocaging structures were identified by our previously proposed strategy of computationally searching for carbocations with low-energy diradical states as a possible indicator of a nearby productive conical intersection. The superior optical properties of these photocages make them promising alternatives to the popular o-nitrobenzyl photocage systems.