109 research outputs found
Strong-field terahertz-optical mixing in excitons
Driving a double-quantum-well excitonic intersubband resonance with a
terahertz (THz) electric field of frequency \omega_{THz} generated terahertz
optical sidebands \omega=\omega_{THz}+\omega_{NIR} on a weak NIR probe. At high
THz intensities, the intersubband dipole energy which coupled two excitons was
comparable to the THz photon energy. In this strong-field regime the sideband
intensity displayed a non-monotonic dependence on the THz field strength. The
oscillating refractive index which gives rise to the sidebands may be
understood by the formation of Floquet states, which oscillate with the same
periodicity as the driving THz field.Comment: 4 pages, 6 figure
Polypeptide-grafted macroporous polyHIPE by surface-initiated N-Carboxyanhydride (NCA) polymerization as a platform for bioconjugation
A new class of functional macroporous monoliths from polymerized high internal phase emulsion (polyHIPE) with tunable surface functional groups was developed by direct polypeptide surface grafting. In the first step, amino-functional polyHIPEs were obtained by the addition of 4-vinylbenzyl or 4-vinylbenzylphthalimide to the styrenic emulsion and thermal radical polymerization. The obtained monoliths present the expected open-cell morphology and a high surface area. The incorporated amino group was successfully utilized to initiate the ring-opening polymer-
ization of benzyl-L-glutamate N-carboxyanhydride (BLG NCA) and benzyloxycarbonyl-L-lysine (Lys(Z)) NCA, which resulted in a dense homogeneous coating of polypeptides throughout the internal polyHIPE surfaces as confirmed by SEM and FTIR analysis. The amount of polypeptide grafted to the polyHIPE surfaces could be modulated by varying the initial ratio of amino acid NCA to amino-functional polyHIPE. Subsequent removal of the polypeptide protecting groups yielded highly functional polyHIPE-g-poly(glutamic acid) and polyHIPE-g- poly(lysine). Both types of polypeptide-grafted monoliths responded to pH by changes in their hydrohilicity. The possibility to use the high density of function (âCOOH or âNH2) for secondary reaction was demonstrated by the successful bioconjugation of enhanced green fluorescent protein (eGFP) and fluorescein isocyanate (FITC) on the polymer 3D-scaffold surface. The amount of eGFP and FITC conjugated to the polypeptide-grafted polyHIPE was significantly higher than to the amino- functional polyHIPE, signifying the advantage of polypeptide grafting to achieve highly functional polyHIPEs
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PEGâpeptide conjugates
The remarkable diversity of the self-assembly behavior
of PEGâpeptides is reviewed, including self-assemblies formed by PEGâpeptides with ÎČ-sheet and α-helical (coiled-coil) peptide sequences. The modes of self-assembly in solution and in the solid state are discussed. Additionally, applications in bionanotechnology and synthetic materials science are summarized
Cationic Ring-Opening Polymerization of 2-Propyl-2-oxazolines: Understanding Structural Effects on Polymerization Behavior Based on Molecular Modeling
Secondary Structure-Induced Micro- and Macrophase Separation in Rod-Coil Polypeptide Diblock, Triblock, and Star-Block Copolymers
Efficient Cationic Ring-Opening Polymerization of Diverse Cyclic Imino Ethers: Unexpected Copolymerization Behavior
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