Triazole-Functionalized Mesoporous Materials Based on Poly(styrene- block -lactic acid): A Morphology Study of Thin Films

We report the synthesis of poly(styrene- block -lactic acid) (PS- b -PLA) copolymers with triazole rings as a junction between blocks. These materials were prepared via a ‘click’ strategy which involved the reaction between azide-terminated poly(styrene) (PS-N 3 ) and acetylene-terminated poly(D,L-lactic acid) (PLA-Ac), accomplished by copper-catalyzed azide-alkyne cycloaddition reaction. This synthetic approach has demonstrated to be effective to obtain specific copolymer structures with targeted self-assembly properties. We observed the self-assembly behavior of the PS- b -PLA thin films as induced by solvent vapor annealing (SVA), thermal annealing (TA), and hydrolysis of the as-spun substrates and monitored their morphological changes by means of different microscopic techniques. Self-assembly via SVA and TA proved to be strongly dependent on the pretreatment of the substrates. Microphase segregation of the untreated films yielded a pore size of 125 nm after a 45-min SVA. After selectively removing the PLA microdomains, the as-spun substrates exhibited the formation of pores on the surface, which can be a good alternative to form an ordered pattern of triazole functionalized porous PS at the mesoscale. Finally, as revealed by scanning electron microscopy–energy dispersive X-ray spectroscopy, the obtained triazole-functionalized PS-porous film exhibited some affinity to copper (Cu) in solution. These materials are suitable candidates to further study its metal-caption properties

Localized atmospheric plasma sintering of inkjet printed silver nanoparticles

Atmospheric pressure argon plasma sintering of silver nanoparticle inks was investigated to improve the plasma sintering process in terms of sintering speed, substrate friendliness and technical complexity. Sintering times were reduced to several seconds while achieving similar conductivity values of above 10% compared to bulk silver. Sintering can be carried out under ambient conditions at specific locations without exposing the entire substrate. Plasma sintering at atmospheric pressure exhibits the capability to be used in roll-to-roll production processes

Optimized Encapsulation of the FLAP/PGES-1 Inhibitor BRP-187 in PVA-Stabilized PLGA Nanoparticles Using Microfluidics

The dual inhibitor of the 5-lipoxygenase-activating protein (FLAP) and the microsomal prostaglandin E2 synthase-1 (mPGES-1), named BRP-187, represents a promising drug candidate due to its improved anti-inflammatory efficacy along with potentially reduced side effects in comparison to non-steroidal anti-inflammatory drugs (NSAIDs). However, BRP-187 is an acidic lipophilic drug and reveals only poor water solubility along with a strong tendency for plasma protein binding. Therefore, encapsulation in polymeric nanoparticles is a promising approach to enable its therapeutic use. With the aim to optimize the encapsulation of BRP-187 into poly(lactic-co-glycolic acid) (PLGA) nanoparticles, a single-phase herringbone microfluidic mixer was used for the particle preparation. Various formulation parameters, such as total flow rates, flow rate ratio, the concentration of the poly(vinyl alcohol) (PVA) as a surfactant, initial polymer concentration, as well as presence of a co-solvent on the final particle size distribution and drug loading, were screened for best particle characteristics and highest drug loading capacities. While the size of the particles remained in the targeted region between 121 and 259 nm with low polydispersities (0.05 to 0.2), large differences were found in the BRP-187 loading capacities (LC = 0.5 to 7.29%) and drug crystal formation during the various formulations

Dual pH and ultrasound responsive nanoparticles with pH triggered surface charge-conversional properties

A series of dual pH-and ultrasound responsive statistical copolymers were synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization of 3,4- dihydro-2H-pyran (DHP) protected HEMA 2-(( tetrahydro-2H-pyran-2-yl) oxy) ethyl methacrylate (THP-HEMA) and 2-(dimethylamino) ethyl methacrylate (DMAEMA). The RAFT-controlled nature of the (co) polymerizations was verified by detailed kinetic studies. The chemical structure and the co-monomer composition of the copolymers were confirmed by H-1 NMR spectroscopy. The number- average molar mass values (Mn) and dispersities (DM =M-w/M-n) of the copolymers were estimated by size exclusion chromatography (SEC). The thermal properties of the (co) polymers were analyzed by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Additionally, the DMAEMA moieties of the copolymers were quaternized with an excess of methyl iodide. The synthesized polymers self- assemble into nanoparticles in aqueous media via the nanoprecipitation method and were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Zeta potential measurements revealed that all DMAEMA containing nanoparticles undergo a surface charge conversion from positive to negative at slightly acidic pH values. However, quaternized DMAEMA nanoparticles possess pH independent positive surface charges. At acidic pH values, the nanoparticles disassemble and dissolve in water due to the protonation of the DMAEMA moieties and/or due to the acidic hydrolysis of the THP-HEMA groups. It was found that the surface charge and the stability of the nanoparticles were greatly affected by the DMAEMA content of the polymers, meaning that the isoelectric point (IEP), at which the charge is reversed and the pH value at which the disassembly occurs, increased with the higher DMAEMA content in the copolymer. Moreover, it was proven that the ionization of the carboxyl RAFT end-group of the polymers enhanced the anionic character and the stability of the nanoparticles at neutral pH values. DLS and scanning electron microscopy (SEM) measurements revealed that these nanoparticles can be further disrupted by ultrasound exposure. Nile Red was encapsulated into nanoparticles as a model hydrophobic drug. The release profile of the Nile Red was significantly accelerated in acidic media or under ultrasound exposure. The cytotoxicity assay results showed that negatively charged nanoparticles are non-toxic and biocompatible, whereas positively charged nanoparticles are extremely toxic to L929 cells

Compatible Solution‐Processed Interface Materials for Improved Efficiency of Polymer Solar Cells

Abstract The electron transport layer (ETL) in an organic solar cell is one of the main components that play a crucial role in the extraction of charges, improving efficiency, and increasing the lifetime of the solar cells. Herein, solution‐processed PBDTTT‐C‐T:PC71BM‐based organic solar cells are fabricated using conjugated PDINO molecules, sol‐gel derived under stoichiometric titanium oxide (TiOx), and a mixture of the same as an ETL. For PBDTTT‐C‐T:PC71BM‐based organic solar cells, a blend of organic‐inorganic ETLs demonstrates reduced bimolecular recombination and trap‐assisted recombination than a single ETL of either two materials. Furthermore, in both, fullerene and nonfullerene systems, the efficiency of the devices employing the blend ETL as compared to the single ETLs show some performance improvement. The strategy of integrating compatible organic and inorganic interface materials to improve device efficiency and lifetime simultaneously, and demonstrate the universality of different systems, has potential significance for the commercial development of organic solar cells

Dual Responsive Nanoparticles from a RAFT Copolymer Library for the Controlled Delivery of Doxorubicin

In this study, we designed, synthesized, and characterized a novel pH- and redox responsive nanoparticle system for the enhanced spatial delivery of hydrophobic drugs. A statistical copolymer library of pyridyldisulfide ethyl methacrylate (PDSM) with different compositions of 2-((<i>tert</i>-butoxycarbonyl)­(2-((<i>tert</i>-butoxycarbonyl)­amino)­ethyl)­amino)­ethyl methacrylate (BocAEAEMA) was synthesized using the reversible addition–fragmentation chain transfer (RAFT) polymerization process. The controlled nature of the radical polymerization was demonstrated by a kinetic study. The Boc-groups were cleaved to obtain the desired amino functional copolymers. Nanoparticles were prepared by nanoprecipitation and characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Differently sized nanoparticles that have monomodal size distributions ranging from 50 to 460 nm with positive ζ-potential values were obtained by varying initial conditions of the formulations. The pH- and redox responsiveness of the nanoparticle systems was investigated by the DLS and ζ-potential measurements. The pH-responsiveness test results demonstrated that the obtained nanoparticles reveal a pH response, such as changes in the size and ζ-potential values upon pH value change. Moreover, redox responsiveness tests revealed the stability of the nanoparticles at a glutathione (GSH) concentration found in the plasma of the human body (10 μM) and the disassembly ability of the nanoparticles in a mimicking intracellular reductive environment (10 mM GSH). The antitumor drug doxorubicin (DOX) was used to investigate the encapsulation and release capability of the nanoparticles. Release studies showed that the DOX release was significantly accelerated in the presence of 10 mM GSH compared to the physiological conditions. Confocal laser scanning microscopy (CLSM) studies indicated that DOX-loaded nanoparticles were taken up efficiently by HEK cells, and DOX was released from the nanoparticles and interacted with the chromosomes in the cell nuclei after 6 h. Cytotoxicity tests revealed that DOX-loaded nanoparticles decreased the cell viability in a concentration and time dependent manner comparable or even better as the free DOX, whereas pure particles are biocompatible