High-purity, symmetrically substituted perylene and naphthalene bisimides were obtained by hydrothermal condensation of monoamines with the corresponding bisanhydride. The hydrothermal imidization proceeds quantitatively, without the need for organic solvents, catalysts or excess of the amines.

In the past decades, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has been applied to a broad range of biological samples, e.g., forensics and preclinical samples. The use of MALDI-MSI for the analysis of bone tissue has been limited due to the insulating properties of the material but more importantly the absence of a proper sample preparation protocol for undecalcified bone tissue. Undecalcified sections are preferred to retain sample integrity as much as possible or to study the tissue-bone bio interface in particular. Here, we optimized the sample preparation protocol of undecalcified bone samples, aimed at both targeted and untargeted applications for forensic and preclinical applications, respectively. Different concentrations of gelatin and carboxymethyl cellulose (CMC) were tested as embedding materials. The composition of 20% gelatin and 7.5% CMC showed to support the tissue best while sectioning. Bone tissue has to be sectioned with a tungsten carbide knife in a longitudinal fashion, while the sections need to be supported with double-sided tapes to maintain the morphology of the tissue. The developed sectioning method was shown to be applicable on rat and mouse as well as human bone samples. Targeted (methadone and EDDP) as well as untargeted (unknown lipids) detection was demonstrated. DHB proved to be the most suitable matrix for the detection of methadone and EDDP in positive ion mode. The limit of detection (LOD) is estimated to approximately 50 pg/spot on bone tissue. The protocol was successfully applied to detect the presence of methadone and EDDP in a dosed rat femur and a dosed human clavicle. The best matrices for the untargeted detection of unknown lipids in mouse hind legs in positive ion mode were CHCA and DHB based on the number of tissue-specific peaks and signal-to-noise ratios. The developed and optimized sample preparation method, applicable on animal and human bones, opens the door for future forensic and (pre)clinical investigations.

The formation of networks through light-initiated radical polymerization allows little freedom for tailored network design. The resulting inhomogeneous network architectures and brittle material behavior of such glassy-type networks limit the commercial application of photopolymers in 3D printing, biomedicine, and microelectronics. An ester-activated vinyl sulfonate ester (EVS) is presented for the rapid formation of tailored methacrylate-based networks. The chain transfer step induced by EVS reduces the kinetic chain length of the photopolymer, thus shifting the gel point to higher conversion, which results in reduced shrinkage stress and higher overall conversion. The resulting, more homogeneous network is responsible for the high toughness of the material. The unique property of EVS to promote nearly retardation-free polymerization can be attributed to the fact that after the transfer step no polymerizable double bond is formed, as is usually seen in classical chain transfer agents. Laser flash photolysis, theoretical calculations, and photoreactor studies were used to elucidate the fast chain transfer reaction and exceptional regulating ability of EVS. Final photopolymer networks exhibit improved mechanical performance making EVS an outstanding candidate for the 3D printing of tough photopolymers.

Matrix-assisted laser desorption/ionisation mass spectrometric imaging (MALDI MSI) is a technique that provides localized information on intact molecules in a sample. Micro X-ray fluorescence (μXRF) imaging allows the examination of the spatial distribution of elements in a sample without any morphological changes. These methods have already been applied separately to different tissues, organs, plants and bacterial films, but, to the best of our knowledge, they have yet to be coupled in a multimodal analysis. In this proof-of-principle study, we established and tested sample preparation strategies, allowing the multimodal analysis of lipids (sphingomyelin and phosphatidylcholines) and elements relevant to bone structures as calcium, phosphorous and sulphur in the very same sample section of a chicken phalanx without tissue decalcification. The results of the investigation of such parameters as adhesive tapes supporting tissue sections, and the sequence of the imaging experiments are presented. We show specific lipid distributions in skin, cartilage, muscle, nail, and the intact morphology of bone by calcium and phosphorus imaging. A combination of molecular and elemental imaging was achieved, thus, providing now for the first time the possibility of gathering MALDI MSI and μXRF information from the very same sample without any washing steps omitting therefore the analytical artifacts that inevitably occur in approaches using consecutive tissue sections. The proposed combination can benefit in research studies regarding bone diseases, osteoporosis, osteoarthritis, cartilage failure, bone/tendon distinguishing, where elemental and lipid interaction play an essential role.

No abstract

No abstract

Chain transfer agents (e.g., thiols) enrich radical photopolymerization for use in advanced applications such as stereolithography, optical materials, and biomedicine. Resulting thiol‐ene‐based photopolymers exhibit numerous benefits such as tunable thermomechanical properties, and give access to spatially resolved functional materials. Silane‐ene chemistry could serve as alternative to this popular thiol‐ene approach. A monosubstituted bis(trimethylsilyl)silane (MSiH) is synthesized by a simple one pot procedure. Photoinitiated radical silane‐ene chemistry has been performed with multiple enes and the conversions are assessed by 1H NMR spectroscopy. Compared to the most reactive silane from literature, tris(trimethylsilyl)silane (TTMSSiH), the radical reactivity of MSiH is reduced in all tested formulations, but the possibility for further functionalization and accessibility of multifunctional MSiH‐derivatives is upheld. A silane‐acrylate formulation is found to be most promising. In comparison to a thiol‐acrylate system, a more uniform conversion of the chain transfer agent and acrylate is shown for the silane‐acrylate formulation with MSiH. The promising results for the silane‐acrylate system are confirmed by further tests (i.e., NMR spectroscopy, GPC, and MALDI MS), giving additional information on molecular weight regulation and radical mechanism. First MSiH‐based photopolymer networks have been fabricated and analyzed via DMTA, thus paving the way for future silane‐acrylate networks.

Die Netzwerkbildung während der lichtinitiierten radikalischen Polymerisation erfolgt ungeregelt und ist nicht einfach zu kontrollieren. Die entstehenden Photopolymere besitzen eine inhomogene Netzwerkarchitektur, welche in sprödem Materialverhalten resultiert und somit die Anwendung beispielsweise für den 3D‐Druck, Biomedizin und Mikroelektronik limitiert. In dieser Arbeit wird ein Ester‐aktivierter Vinylsulfonatester (EVS) präsentiert, der die schnelle Bildung von geregelten Methacrylat‐basierten Netzwerken ermöglicht. Der durch EVS eingeleitete Kettenübertragungsschritt reduziert die kinetische Kettenlänge des Photopolymers und verschiebt den Gelpunkt zu höheren Umsätzen. Dies hat eine geringere polymerisationsinduzierte Schrumpfspannung und einen höheren Gesamtumsatz zur Folge. Das gebildete gleichmäßigere Polymernetzwerk ist der Grund für die hohe Zähigkeit des Endmaterials. Die einzigartige Fähigkeit von EVS zur nahezu verzögerungsfreien Polymerisation basiert auf der Tatsache, dass nach dem Kettenübertragungsschritt keine Doppelbindung gebildet wird, die weiterreagieren könnte. Laser‐Blitzlichtphotolyse, theoretische Berechnungen und Photoreaktorstudien machen den schnellen Kettenübertragungsschritt und die außergewöhnlichen Netzwerkregelungseigenschaften von EVS verständlich. Die resultierenden Polymere weisen verbesserte mechanische Eigenschaften auf, was EVS zu einem ausgezeichneten Kandidaten für den lithographiebasierten 3D‐Druck von zähen Photopolymeren macht.