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2.
Yao Jin Friederike Adams Judith Möller Lorenz Isert Christoph M. Zimmermann David Keul Olivia M. Merkel 《Macromolecular bioscience》2023,23(2):2200409
Polyethylenimine (PEI) is a commonly used cationic polymer for small-interfering RNA (siRNA) delivery due to its high transfection efficiency at low commercial cost. However, high molecular weight PEI is cytotoxic and thus, its practical application is limited. In this study, different formulations of low molecular weight PEI (LMW-PEI) based copolymers polyethylenimine-g-polycaprolactone (PEI–PCL) (800 Da–40 kDa) and PEI–PCL–PEI (5–5–5 kDa) blended with or without polyethylene glycol-b-polycaprolactone (PEG–PCL) (5 kDa-4 kDa) are investigated to prepare nanoparticles via nanoprecipitation using a solvent displacement method with sizes ≈100 nm. PEG–PCL can stabilize the nanoparticles, improve their biocompatibility, and extend their circulation time in vivo. The nanoparticles composed of PEI–PCL–PEI and PEG–PCL show higher siRNA encapsulation efficiency than PEI–PCL/PEG–PCL based nanoparticles at low N/P ratios, higher cellular uptake, and a gene silencing efficiency of ≈40% as a result of the higher molecular weight PEI blocks. These results suggest that the PEI–PCL–PEI/PEG–PCL nanoparticle system could be a promising vehicle for siRNA delivery at minimal synthetic effort. 相似文献
3.
Porous and Shape‐Anisotropic Single Crystals of the Semiconductor Perovskite CH3NH3PbI3 from a Single‐Source Precursor 下载免费PDF全文
Tom Kollek Dominik Gruber Julia Gehring Eugen Zimmermann Prof. Dr. Lukas Schmidt‐Mende Prof. Dr. Sebastian Polarz 《Angewandte Chemie (International ed. in English)》2015,54(4):1341-1346
Significant progress in solar‐cell research is currently made by the development of metal–organic perovskites (MOPs) owing to their superior properties, such as high absorption coefficients and effective transport of photogenerated charges. As for other semiconductors, it is expected that the properties of MOPs may be significantly improved by a defined nanostructure. However, their chemical sensitivity (e.g., towards hydrolysis) prohibits the application of methods already known for the synthesis of other nanomaterials. A new and general method for the synthesis of various (CH3NH3)PbI3 nanostructures from a novel single‐source precursor is presented. Nanoporous MOP single crystals are obtained by a crystal‐to‐crystal transformation that is accompanied by spinodal demixing of the triethylene glycol containing precursor structure. Selective binding of a capping agent can be used to tune the particle shape of the MOP nanocrystals. 相似文献
4.
Identification of Structure–Activity Relationships from Screening a Structurally Compact DNA‐Encoded Chemical Library 下载免费PDF全文
Dr. Raphael M. Franzini Dr. Torun Ekblad Dr. Nan Zhong Moreno Wichert Willy Decurtins Angela Nauer Mauro Zimmermann Dr. Florent Samain Dr. Jörg Scheuermann Dr. Peter J. Brown Prof. Dr. Jonathan Hall Dr. Susanne Gräslund Prof. Dr. Herwig Schüler Prof. Dr. Dario Neri 《Angewandte Chemie (International ed. in English)》2015,54(13):3927-3931
Methods for the rapid and inexpensive discovery of hit compounds are essential for pharmaceutical research and DNA‐encoded chemical libraries represent promising tools for this purpose. We here report on the design and synthesis of DAL‐100K, a DNA‐encoded chemical library containing 103 200 structurally compact compounds. Affinity screening experiments and DNA‐sequencing analysis provided ligands with nanomolar affinities to several proteins, including prostate‐specific membrane antigen and tankyrase 1. Correlations of sequence counts with binding affinities and potencies of enzyme inhibition were observed and enabled the identification of structural features critical for activity. These results indicate that libraries of this type represent a useful source of small‐molecule binders for target proteins of pharmaceutical interest and information on structural features important for binding. 相似文献
5.
Two Hexagonal Series of Lanthanoid(III) Oxide Fluoride Selenides: M6O2F8Se3 (M = La – Nd) and M2OF2Se (M = Nd,Sm, Gd – Ho) 下载免费PDF全文
Dirk D. Zimmermann Hagen Grossholz Sarah Wolf Oliver Janka Alexander C. Müller Thomas Schleid 《无机化学与普通化学杂志》2015,641(11):1926-1933
Two hexagonal series of lanthanoid(III) oxide fluoride selenides with similar structure types can be obtained by the reaction of the components MF3, M2O3, M, and Se in sealed niobium tubes at 850 °C using CsI as fluxing agent. The compounds with the lighter and larger representatives (M = La – Nd) occur with the formula M6O2F8Se3, whereas with the heavier and smaller ones (M = Nd, Sm, Gd – Ho) their composition is M2OF2Se. For both systems single‐crystal determinations were used in all cases. The compounds crystallize in the hexagonal crystal system (space group: P63/m) with lattice parameters of a = 1394–1331 pm and c = 403–372 pm (Z = 2 for M6O2F8Se3 and Z = 6 for M2OF2Se). The (M1)3+ cations show different square antiprismatic coordination spheres with or without an extra capping fluoride anion. All (M2)3+ cations exhibit a ninefold coordination environment shaped as tricapped trigonal prism. In both structure types the Se2– anions are sixfold coordinated as trigonal prisms of M3+ cations, being first condensed by edges to generate trimeric units and then via faces to form strands running along [001]. The light anions reside either in threefold triangular or in fourfold tetrahedral cationic coordination. For charge compensation, both structures have to contain a certain amount of oxide besides fluoride anions. Since F– and O2– can not be distinguished by X‐ray diffraction, bond‐valence calculations were used to address the problem of their adjunction to the available crystallographic sites. 相似文献
6.
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8.
Paola Zimmermann Crocomo Takahito Kaihara Soki Kawaguchi. Dr. Patrycja Stachelek Prof. Dr. Satoshi Minakata Prof. Dr. Piotr de Silva Prof. Dr. Przemyslaw Data Prof. Dr. Youhei Takeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(53):13390-13398
Novel electron donor–acceptor–donor (D-A-D) compounds comprising dibenzo[a,j]phenazine as the central acceptor core and two 7-membered diarylamines (iminodibenzyl and iminostilbene) as the donors have been designed and synthesized. Investigation of their physicochemical properties revealed the impact of C2 insertion into well-known carbazole electron donors on the properties of previously reported twisted dibenzo[a,j]phenazine-core D-A-D triads. Slight structural modification caused a drastic change in conformational preference, allowing unique photophysical behavior of dual emission derived from room-temperature phosphorescence and triplet–triplet annihilation. Furthermore, electrochemical analysis suggested sigma-dimer formation and electrochemical polymerization on the electrode. Quantum chemical calculations also rationalized the experimental results. 相似文献
9.
K. Zimmermann I. Zeidis M. Pivovarov K. Abaza 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(5):353-362
In this paper we discuss an approximately steady motion of an oscillator as a single whole with a constant “on the average”
velocity. For that purpose we analyze the position and stability of some special points of the phase portrait. In the presence
of internal excitation and nonsymmetric Coulomb dry friction, a motion of the oscillator with a constant “on the average”
velocity is possible. The algebraic equation for this constant velocity is found. For different parameters of the model there
exist at most three regimes of motion with a constant velocity, but only one or two of them are stable. The theoretical results
obtained can be used for the design of worm-like moving robots. 相似文献
10.
The deformation of an infinite bar subjected to a self-equilibrated load distribution is investigated using the peridynamic formulation of elasticity theory. The peridynamic theory differs from the classical theory and other nonlocal theories in that it does not involve spatial derivatives of the displacement field. The bar problem is formulated as a linear Fredholm integral equation and solved using Fourier transform methods. The solution is shown to exhibit, in general, features that are not found in the classical result. Among these are decaying oscillations in the displacement field and progressively weakening discontinuities that propagate outside of the loading region. These features, when present, are guaranteed to decay provided that the wave speeds are real. This leads to a one-dimensional version of St. Venant's principle for peridynamic materials that ensures the increasing smoothness of the displacement field remotely from the loading region. The peridynamic result converges to the classical result in the limit of short-range forces. An example gives the solution to the concentrated load problem, and hence provides the Green's function for general loading problems. 相似文献