2019, Machałowski, Tomasz, Wysokowski, Marcin, Tsurkan, Mikhail V., Galli, Roberta, Schimpf, Christian, Rafaja, David, Brendler, Erica, Viehweger, Christine, Zółtowska-Aksamitowska, Sonia, Petrenko, Iaroslav, Czaczyk, Katarzyna, Kraft, Michael, Bertau, Martin, Bechmann, Nicole, Guan, Kaomei, Bornstein, Stefan R., Voronkina, Alona, Fursov, Andriy, Bejger, Magdalena, Biniek-Antosiak, Katarzyna, Rypniewski, Wojciech, Figlerowicz, Marek, Pokrovsky, Oleg, Jesionowski, Teofil, Ehrlich, Hermann

Chitin, as a fundamental polysaccharide in invertebrate skeletons, continues to be actively investigated, especially with respect to new sources and the development of effective methods for its extraction. Recent attention has been focused on marine crustaceans and sponges; however, the potential of spiders (order Araneae) as an alternative source of tubular chitin has been overlooked. In this work, we focused our attention on chitin from up to 12 cm-large Theraphosidae spiders, popularly known as tarantulas or bird-eating spiders. These organisms “lose” large quantities of cuticles during their molting cycle. Here, we present for the first time a highly effective method for the isolation of chitin from Caribena versicolor spider molt cuticle, as well as its identification and characterization using modern analytical methods. We suggest that the tube-like molt cuticle of this spider can serve as a naturally prefabricated and renewable source of tubular chitin with high potential for application in technology and biomedicine. © 2019 by the authors.

2019, Motovilov, K.A., Grinenko, V., Savinov, M., Gagkaeva, Z.V., Kadyrov, L.S., Pronin, A.A., Bedran, Z.V., Zhukova, E.S., Mostert, A.B., Gorshunov, B.P.

Conductive biomolecular systems are investigated for their promise of new technologies. One biomolecular material that has garnered interest for device applications is eumelanin. Its unusual properties have led to its incorporation in a wide set of platforms including transistor devices and batteries. Much of eumelanin's conductive properties are due to a solid state redox comproportionation reaction. However, most of the work that has been done to demonstrate the role of the redox chemistry in eumelanin has been via control of eumelanin's hydration content with scant attention given to temperature dependent behavior. Here we demonstrate for the first time consistency between hydration and temperature effects for the comproportionation conductivity model utilizing dielectric spectroscopy, heat capacity measurements, frequency scaling phenomena and recognizing that activation energies in the range of ∼0.5 eV correspond to proton dissociation events. Our results demonstrate that biomolecular conductivity models should account for temperature and hydration effects coherently.