TY - JOUR A1 - Goychuk, Igor T1 - Sensing magnetic fields with magnetosensitive ion channels JF - Sensors N2 - Magnetic nanoparticles are met across many biological species ranging from magnetosensitive bacteria, fishes, bees, bats, rats, birds, to humans. They can be both of biogenetic origin and due to environmental contamination, being either in paramagnetic or ferromagnetic state. The energy of such naturally occurring single-domain magnetic nanoparticles can reach up to 10-20 room k(B)T in the magnetic field of the Earth, which naturally led to supposition that they can serve as sensory elements in various animals. This work explores within a stochastic modeling framework a fascinating hypothesis of magnetosensitive ion channels with magnetic nanoparticles serving as sensory elements, especially, how realistic it is given a highly dissipative viscoelastic interior of living cells and typical sizes of nanoparticles possibly involved. KW - magnetic nanoparticles KW - ion channels KW - viscoelastic effects and anomalous diffusion KW - non-exponential statistics KW - influence of weak magnetic fields on living systems Y1 - 2018 U6 - https://doi.org/10.3390/s18030728 SN - 1424-8220 VL - 18 IS - 3 PB - MDPI CY - Basel ER - TY - JOUR A1 - Wang, Li A1 - Baudis, Stefan A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Characterization of bi-layered magnetic nanoparticles synthesized via two-step surface-initiated ring-opening polymerization JF - Pure and applied chemistry : official journal of the International Union of Pure and Applied Chemistry N2 - A versatile strategy to integrate multiple functions in a polymer based material is the formation of polymer networks with defined nanostructures. Here, we present synthesis and comprehensive characterization of covalently surface functionalized magnetic nanoparticles (MNPs) comprising a bi-layer oligomeric shell, using Sn(Oct)(2) as catalyst for a two-step functionalization. These hydroxy-terminated precursors for degradable magneto-and thermo-sensitive polymer networks were prepared via two subsequent surfaceinitiated ring-opening polymerizations (ROPs) with omega-pentadecalactone and e-caprolactone. A two-step mass loss obtained in thermogravimetric analysis and two distinct melting transitions around 50 and 85 degrees C observed in differential scanning calorimetry experiments, which are attributed to the melting of OPDL and OCL crystallites, confirmed a successful preparation of the modified MNPs. The oligomeric coating of the nanoparticles could be visualized by transmission electron microscopy. The investigation of degrafted oligomeric coatings by gel permeation chromatography and H-1-NMR spectroscopy showed an increase in number average molecular weight as well as the presence of signals related to both of oligo(omega-pentadecalactone) (OPDL) and oligo(e-caprolactone) (OCL) after the second ROP. A more detailed analysis of the NMR results revealed that only a few.-pentadecalactone repeating units are present in the degrafted oligomeric bi-layers, whereby a considerable degree of transesterification could be observed when OPDL was polymerized in the 2nd ROP step. These findings are supported by a low degree of crystallinity for OPDL in the degrafted oligomeric bi-layers obtained in wide angle X-ray scattering experiments. Based on these findings it can be concluded that Sn(Oct)(2) was suitable as catalyst for the preparation of nanosized bi-layered coated MNP precursors by a two-step ROP. KW - degradable polyester KW - magnetic nanoparticles KW - nanoparticle characterization KW - NICE-2014 KW - ring opening polymerization KW - surface functionalization Y1 - 2015 U6 - https://doi.org/10.1515/pac-2015-0607 SN - 0033-4545 SN - 1365-3075 VL - 87 IS - 11-12 SP - 1085 EP - 1097 PB - De Gruyter CY - Berlin ER -