Lead-binding biogenic polyelectrolyte multilayer coating for lead retention in perovskite solar cells

Perovskite solar cells promise to deliver high efficiencies at low manufacturing costs. Yet on their way towards commercialization, they have to face the associated risk of potential lead leakage into the environment after damage to the cell's encapsulation. Here we present a new approach to generate a lead binding coating, based on a layer-by-layer deposition of biopolymers. A lead-adsorbing functionality was shown after subsequent crosslinking, demonstrating a high binding capacity. The lead binding capabilities could be further enhanced by increasing the thickness of the coatings, analyzed both in the supernatant and on the surface of the coated material. The thin-layered coating had a thickness of less than one micrometer, was stable even under low pH conditions and could successfully be transferred onto different substrates, ranging from silicon, gold and glass substrates to polymeric nonwoven materials with high surface areas, further increasing its lead binding capacity. This newly described coating was applied within perovskite solar cell stacks without impeding the overall efficiency but strongly reducing the amount of lead released after simulated rain tests on devices with damaged encapsulation. Accordingly, incorporation of lead-binding polyelectrolyte multilayers inside the encapsulation of perovskite solar cells shows great potential to limit the perovskite solar cells inherent risk of lead leakage in a sustainable manner.

Encapsulated vaterite-calcite CaCO3 particles loaded with Mg2+ and Cu2+ ions with sustained release promoting osteogenesis and angiogenesis

Bioactive cations, including calcium, copper and magnesium, have shown the potential to become the alternative to protein growth factor-based therapeutics for bone healing. Ion substitutions are less costly, more stable, and more effective at low concentrations. Although they have been shown to be effective in providing bone grafts with more biological functions, the precise control of ion release kinetics is still a challenge. Moreover, the synergistic effect of three or more metal ions on bone regeneration has rarely been studied. In this study, vaterite-calcite CaCO3 particles were loaded with copper (Cu2+) and magnesium (Mg2+). The polyelectrolyte multilayer (PEM) was deposited on CaCuMg-CO3 particles via layer-by-layer technique to further improve the stability and biocompatibility of the particles and to enable controlled release of multiple metal ions. The PEM coated microcapsules were successfully combined with collagen at the outmost layer, providing a further stimulating microenvironment for bone regeneration. The in vitro release studies showed remarkably stable release of Cu2+ in 2 months without initial burst release. Mg2+ was released in relatively low concentration in the first 7 days. Cell culture studies showed that CaCuMg-PEM-Col microcapsules stimulated cell proliferation, extracellular maturation and mineralization more effectively than blank control and other microcapsules without collagen adsorption (Ca-PEM, CaCu-PEM, CaMg-PEM, CaCuMg-PEM). In addition, the CaCuMg-PEM-Col microcapsules showed positive effects on osteogenesis and angiogenesis in gene expression studies. The results indicate that such a functional and controllable delivery system of multiple bioactive ions might be a safer, simpler and more efficient alternative of protein growth factor-based therapeutics for bone regeneration. It also provides an effective method for functionalizing bone grafts for bone tissue engineering.

Enhanced Bioavailability of Dihydrotanshinone I-Bovine Serum Albumin Nanoparticles for Stroke Therapy

Dihydrotanshinone I (DHT) is a natural component in Salvia miltiorrhiza and has been widely researched for its multiple bioactivities. However, poor solubility and biocompatibility of DHT limit its desirable application for clinical purposes. Herein, DHT was encapsulated with bovine serum albumin (BSA) to enhance bioavailability. Compared to free DHT, DHT-BSA NPs (nanoparticles) showed an improved solubility in normal saline and increased protection against hydrogen peroxide-induced oxidative damage in PC12 cells. In addition, DHT-BSA NPs administered by intravenous injection displayed a significant efficacy in the middle cerebral artery occlusion/reperfusion models, without any impact on the cerebral blood flow. In summary, DHT-BSA NPs show an enhanced bioavailability compared with free DHT and a successful penetration into the central nervous system for stroke therapy, demonstrating their application potential in cardio-cerebrovascular diseases.

Ein Beitrag zur photoinduzierten Desaminierung substituierter 1.2.4-Triazinone / A Contribution to the Photoinduced Desamination of 1,2,4-Triazinones

Solution-phase photoreactions of 4-amino-substituted 1,2,4-triazin-5(4H)-ones (1a-j) in different solvents using UV light with wavelengths greater than 290 nm have been investigated. The results show, that the desamination reaction is influenced by both oxygen and water. The photoexperiments showed clearly that OOH-radicals take part in the first step of reaction.

Ein Beitrag zur Zusammensetzung des Insektizides "Toxaphen®" Gaschromatographisch-massenspektroskopische Charakterisierung eines öligen und eines kristallinen Anteils des technischen Toxaphens und dessen insektizide Wirksamkeit / A Contribution to the Composition of the Insecticide "Toxaphene®" Gaschromatographic-Masspectroscopical Characterisation of the Oily and the Crystalline Fraction of Technical Toxaphene and their Insecticidal Activity

Technical Toxaphene can be separated in two fractions by recrystallisation which are investigated with the help of GC/MS and toxicological methods. Especially the Retro-Diels-Alder-fragmentations give specific informations on the structure of highly chlorinated bornane derivatives representing the main components of the technical mixture. For this study lower chlorinated bornanes are used as model substances. Toxicological investigations show that both fractions have lower activity than technical toxaphene.

Reaktionen von cis-Crotonsäurederivaten mit Cyclopentadien in heterogener Phase/ Reaction between cis-Crotonic Acid Derivatives and Cyclopentadiene in the Heterogeneous Phase

Diels-Alder reactions between cyclopenta-diene and cis-crotonic acid derivatives were examined in the absorbed phase on various surfaces. The results indicate considerable differences under these conditions in the relative yields of exo and endo isomers. On silica gel, montigel, and aluminium oxide the reactions give mainly endo isomers.

Mineralisierung von 14CCl2F2 durch Oberflächenkatalyse / Mineralisation of 14CCl2F2 Catalysed by Active Surfaces

The reaction behaviour of CCl2F2 adsorbed on silica gel and a natural adsorbent (Mecca Sand) was investigated by means of the 14C-labelled compound. While in the dark no conversion of the substance on silica gel was detected, a significant degradation to 14CO2 was observed on the dry sand. The mineralisation (up to 70%) was due to the applied amount of sand. On irradiation with UV light (λ > 290 nm) the 14CCl2F2 adsorbed on silica gel was partially degraded to 14CO2. However, the mineralisation rate of about 1 % was of less importance in comparison to the rate on the dry sand. The results indicate that the mineralisation takes place at “active sites” on the surface.

Zur Struktur von verbrückten Photoisomeren der Cyclodieninsektizide / Structure of Bridged Photoisomers of Cyclodiene Insecticides

Asymmetrically substituted chlorinated tetrahydro-4,7-methano-1H-indanes can be bridged photochemically into two types of isomerization products. These photoisomers can be distinguished on the basis of different geminal coupling constants in their 1H NMR spectra. The structural assignment is not always certain, given only one photoisomer; it is unambiguous when both isomers are available.

Zur Synthese von 2.5-und 2.6-verbrückten Tetrahydromethanoindanen / Synthesis of 2,5-and 2,6-Crosslinked Tetrahydromethanoindanes

A direct synthetic method for some 2,5-and 2.6-crosslinked chlorinated tetrahydromethano-indanes, which are the most important conversion products of cyclodiene insecticides under abiotic conditions, is described. The structures of the resulting compounds are confirmed with the aid of MS and 1H NMR.