Single‐walled carbon nanotubes (SWCNTs) are a 1D nanomaterial that shows fluorescence in the near‐infrared (NIR, >800 nm). In the past, covalent chemistry was less explored to functionalize SWCNTs as it impairs NIR emission. However, certain sp3 defects (quantum defects) in the carbon lattice have emerged that preserve NIR fluorescence and even introduce a new, red‐shifted emission peak. Here, we report on quantum defects, introduced using light‐driven diazonium chemistry, that serve as anchor points for peptides and proteins. We show that maleimide anchors allow conjugation of cysteine‐containing proteins such as a GFP‐binding nanobody. In addition, an Fmoc‐protected phenylalanine defect serves as a starting point for conjugation of visible fluorophores to create multicolor SWCNTs and in situ peptide synthesis directly on the nanotube. Therefore, these quantum defects are a versatile platform to tailor both the nanotube's photophysical properties as well as their surface chemistry. 相似文献
The diffusive behavior of nanoparticles inside porous materials is attracting a lot of interest in the context of understanding, modeling, and optimization of many technical processes. A very powerful technique for characterizing the diffusive behavior of particles in free media is dynamic light scattering (DLS). The applicability of the method in porous media is considered, however, to be rather difficult due to the presence of multiple sources of scattering. In contrast to most of the previous approaches, the DLS method was applied without ensuring matching refractive indices of solvent and porous matrix in the present study. To test the capabilities of the method, the diffusion of spherical gold nanoparticles within the interconnected, periodic nanopores of inverse opals was analyzed. Despite the complexity of this system, which involves many interfaces and different refractive indices, a clear signal related to the motion of particles inside the porous media was obtained. As expected, the diffusive process inside the porous sample slowed down compared to the particle diffusion in free media. The obtained effective diffusion coefficients were found to be wave vector-dependent. They increased linearly with increasing spatial extension of the probed particle concentration fluctuations. On average, the slowing-down factor measured in this work agrees within combined uncertainties with literature data.
Polynuclear species of zirconium in acidic aqueous solution are investigated by combining X-ray absorption spectroscopy (XAFS)
and nanoelectrospray mass spectrometry (ESI-MS). Species distributions are measured between pHC 0 and pHC 3 for [Zr] = 1.5–10 mM. While the monomer remains a minor species, with increasing pH the degree of polymerization increases
and the formation of tetramers, pentamers, octamers, and larger polymers is observed. The high resolution of the mass spectrometer
permits the unambiguous determination of polynuclear zirconium hydroxide complexes by means of their isotopic patterns. The
relative abundances of mononuclear and polynuclear species present simultaneously in solution are measured, even if one of
the species contributes only 0.1% of the Zr concentration. For the first time it has been directly observed that the hydrolysis
of polynuclear Zr species is a continuous process which leads to charge compensation through the sequential substitution of
water molecules by hydroxide ligands until doubly charged polymers dominate at conditions (H+ and Zr concentrations) close to the solubility of Zr(OH)4(am). The invasiveness of the electrospray process was minimized by using very mild declustering conditions, leaving the polynuclear
species within a solvent shell of approximately 20 water molecules.
Figure Schematic Diagram of Multiplexed Measurement of 9 Anti-Nuclear Antibodies Using the AtheNa Multilyte Assay 相似文献
Abstract Attempts to utilize C-ethylenic phosphaalkenes in metathesis reactions are discussed. Unprecedented reactivity is observed where the vinylphosphaalkene undergoes the first step of the catalytic cycle and cross-metathesis with the phenylmethylene moiety of Grubbs 2nd generation catalyst. However, homo-metathesis reaction to form 1,6-diphosphahexa-1,3,5-triene is not observed, presumably due to steric constraints. 相似文献
A synthetic route to the pulvomycin class of natural products is presented, which culminated in the first synthesis of a pulvomycin, pulvomycin D. Key elements of the strategy include a pivotal aldol reaction which led to bond formation between the C24-C40 and the C8-C23 fragment. The remaining C1-C7 fragment was attached by a Yamaguchi esterification completing the assembly of the 40 carbon atoms within the main skeleton. Ring closure to the 22-membered lactone ring was achieved in the final stages of the synthesis by a Heck reaction. The completion of the synthesis required the removal of six silyl protecting groups in combination with olefin formation at C26-C27 by a Peterson elimination. 相似文献
The 2H or ABAB… structure may be transformed to the 4H or ABCB… structure if deformation faults occur in a non-random manner. The theory of X-ray diffraction from one-dimensionally disordered crystals undergoing the 2H → 4H structural transformation by the deformation mechanism is developed. For this it is necessary to consider that the faults are not distributed entirely at random but tend to occur in such a manner as to statistically create a 4H structure. The X-ray diffraction effects are predicted. 相似文献
Although models of branching in arterial and bronchial trees often predict a dependence of bifurcation parameters on the scale of the bifurcating vessels, direct verification of this dependence by comparison with data is uncommon. We compare measurements of bifurcation parameters of airways and arterial trees of different mammals as a function of scale to general features predicted by theoretical models based on minimization of pumping power and network volume. We find that the size dependence is more complex than existing theories based solely on energy and volume minimization explain, and suggest additional factors that may govern the branching at different scales. 相似文献