Facile production of ultra-fine silicon nanoparticles

A facile procedure for the synthesis of ultra-fine silicon nanoparticles without the need for a Schlenk vacuum line is presented. The process consists of the production of a (HSiO1.5)n sol–gel precursor based on the polycondensation of low-cost trichlorosilane (HSiCl3), followed by its annealing and etching. The obtained materials were thoroughly characterized after each preparation step by electron microscopy, Fourier transform and Raman spectroscopy, X-ray dispersion spectroscopy, diffraction methods and photoluminescence spectroscopy. The data confirm the formation of ultra-fine silicon nanoparticles with controllable average diameters between 1 and 5 nm depending on the etching time

Wpływ dodecylosiarczanu sodu na zachowanie termoczułych polimerów i ich mieszanin w roztworze

The process of thermal aggregation in water of thermoresponsive (co)polymers poly(N-isopropylacrylamide) PNIPAM, poly{[di(ethylene glycol) monomethyl ether methacrylate]-co-[oligo(ethylene glycol) monomethyl ether methacrylate]} P(D-co-O300), the bioconjugate of P(D-co-O300) with the peptide metenkephalin (MetDns) and their mixtures was investigated. The effect of the SDS (sodium dodecyl sulfate) addition on the behavior of thermoresponsive chains was evaluated by UV-Vis (ultraviolet-visible spectroscopy) and DLS (dynamic light scattering) methods. It was found that the presence of SDS influences the polymer transition temperature. It also reduces the size of the aggregates, which explains the higher transmittance value of the solution above phase transition.Zbadano proces termicznej agregacji w wodzie termoczułych (ko)polimerów PNIPAM [poli(N-izopropyloakryloamidu)], P(D-co-O300) [poli(metakrylanu eteru monometylowego glikolu dietylenowego-co-metakrylanu eterumonometylowego glikolu oligoetylenowego)], koniugatu P(D-co-O300) z peptydem metenkefaliną (MetDns) oraz ich mieszanin. Metodami UV-Vis (spektroskopia w ultrafiolecie i świetle widzialnym) i DLS (dynamiczne rozpraszanie światła) oceniono wpływ dodatku dodecylosiarczanu sodu (SDS) na zachowanie termoczułych łańcuchów. Stwierdzono, że obecność SDS wpływa na temperaturę przejścia polimerów. Powoduje także zmniejszenie rozmiaru agregatów, co wyjaśnia większą wartość transmitancji roztworu powyżej przejścia

Micellization of Polystyrene-b-Polyglycidol in Dioxane and Water/Dioxane Solutions

In this work, the self-assembly of a series of amphiphilic polystyrene-b-polyglycidol (PS-b-PGL) diblock copolymers in dioxane and dioxane/water mixtures is presented. The PS-b-PGL have an average degree of polymerization (DP) of PS block equal to 29 units and varied degrees of polymerization for the glycidol segments with DPs of 13, 42, 69 and 117. In dioxane, amphiphilic diblock copolymers form micelles with the hydrophilic PGL placed in the core. Critical micelle concentration (CMC) was determined based on the intensity of scattered light vs. concentration. The micelle size was measured by dynamic light scattering and transmission electron microscopy. Also, the behaviour of the copolymer was studied in water/dioxane solutions by following the changes of scattered light intensity with the addition of water to the system. Critical water content (CWC) of the studied systems decreased as the initial PS-b-PGL concentration in dioxane increased. This process was accompanied by a decrease in the size of aggregate formed. For a given initial copolymer concentration, the size of copolymer aggregates decreased linearly with increasing the length of the PGL bloc

Exciplex Enhancement as a Tool to Increase OLED Device Efficiency

Organic electronics, mainly due to advancements in OLED (organic light-emitting diode) technology, is a fast developing research area having already revolutionized the displays market. This direction presents the use of exciplex emitters and thermally activated delayed fluorescence (TADF) in OLEDs, to give efficient, stable emitters that do not use scarce and expensive materials such as iridium. Here, it is shown for the first time several diketopyrrolopyrrole (DPP) derivatives that could be used as emitters in OLED devices. We were able to improve the efficiency of DPP materials by forming exciplex-enhanced OLED devices. These organic materials were also characterized by electrochemical and spectroscopic methods in order to elucidate each molecule's interaction and decrease the photoluminescence efficiency

Smart Polymeric Nanocarriers of Met-enkephalin

This study describes a novel approach to polymeric nanocarriers of the therapeutic peptide met-enkephalin based on the aggregation of thermoresponsive polymers. Thermoresponsive bioconjugate poly­((di­(ethylene glycol) monomethyl ether methacrylate)-<i>ran</i>-(oligo­(ethylene glycol) monomethyl ether methacrylate) is synthesized by AGET ATRP using modified met-enkephalin as a macroinitiator. The abrupt heating of bioconjugate water solution leads to the self-assembly of bioconjugate chains and the formation of mesoglobules of controlled sizes. Mesoglobules formed by bioconjugates are stabilized by coating with cross-linked two-layer shell via nucleated radical polymerization of <i>N</i>-isopropylacrylamide using a degradable cross-linker. The targeting peptide RGD, containing the fluorescence marker carboxyfluorescein, is linked to a nanocarrier during the formation of the outer shell layer. In the presence of glutathione, the whole shell is completely degradable and the met-enkephalin conjugate is released. It is anticipated that precisely engineered nanoparticles protecting their cargo will emerge as the next-generation platform for cancer therapy and many other biomedical applications