Dose response and time course of manganeseenhanced magnetic resonance imaging for visual pathway tracing in vivo

Axonal tracing is useful for detecting optic nerve injury and regeneration,but many commonly used methods cannot be used to observe axoplasmic flow and synaptic transmission in vivo.Manganese（Mn^2＋）-enhanced magnetic resonance imaging（MEMRI） can be used for in vivo longitudinal tracing of the visual pathway.Here,we explored the dose response and time course of an intravitreal injection of Mn Cl2 for tracing the visual pathway in rabbits in vivo using MEMRI.We found that 2 m M Mn Cl2 enhanced images of the optic nerve but not the lateral geniculate body or superior colliculus,whereas at all other doses tested（5–40 m M）,images of the visual pathway from the retina to the contralateral superior colliculus were significantly enhanced.The images were brightest at 24 hours,and then decreased in brightness until the end of the experiment（7 days）.No signal enhancement was observed in the visual cortex at any concentration of Mn Cl2.These results suggest that MEMRI is a viable method for temporospatial tracing of the visual pathway in vivo.Signal enhancement in MEMRI depends on the dose of Mn Cl2,and the strongest signals appear 24 hours after intravitreal injection.

Affinity Switching for Lysozyme and Dual-responsive Microgels by Stopped-flow Technique： Kinetic Control and Activity Evaluation

The use of proteins as therapeutics in nanomedicine is an emerging research field and has developed rapidly.However,proteins are always vulnerable to renal excretion or digestion by the proteolytic system in vivo,which limits their usage to a large extent.Although biocompatible polymers have been covalently linked to proteins to protect them from recognition by the immune system and prolong their circulation time,the biological activity of them is sometimes decreased.To fill this gap,physical isolation,wrapping,or encapsulation techniques are employed.Up to now,various mature examples were reported,but the whole time scales for guest molecules loading and releasing,especially the initial rapid loading process,were rarely mentioned.Herein,a series of dual-responsive poly（N-isopropylacrylamide-co-methacrylic acid）（P（NIPAM-co-MAA）） microgels were synthesized and employed to investigate the kinetics of in situ complexation and release of lysozyme under external stimuli modulation upon a stopped-flow apparatus,which was suitable for rapid dynamic monitoring.Close inspection of the adsorption kinetics during the early stages（〈 50 s） revealed that the initial microgel collapse occurred within ~1 s,with more rapid transitions being observed when higher lysozyme concentrations were targeted.All the dynamic traces could be well fitted with a double exponential function,suggesting a fast（τ1） and a slow（τ2） relaxation time,respectively.Then,the kinetics of releasing bound lysozyme from microgels was carried on by utilizing the p H-responsive property,and the evaluation of the activity of released lysozyme was synchronously measured in a Micrococcus lysodeikticus（M.lysodeikticus） cell suspension.The corresponding relaxation time（τ） was also calculated by fitting the recorded dynamic traces.We speculate that this work can provide basic dynamics data and theoretical basis for microgels based nanocarriers to be used for protein delivery,controlled release,and possible chemical separation.

Magnetic field effects in organic light-emitting diodes with Co electrode

Tris-（8-hydroxyquinoline）-aluminum eAlq3T–based organic light-emitting diodes with Co electrode are fabricated. The positive magnetic electroluminescence（MEL） and magnetic conductance（MC） are observed in the samples, reaching 4.35% and 1.67% under the field of 42 m T at 50 K, respectively, and the MEL and MC traces can be fitted to non-Lorentzian line shapes. The MEL varies as a function of the Co thickness and reaches the optimal value at 10 nm. The MEL and MC dependence on voltage and temperature is also investigated. The electron-hole pair model and the spin-polarized injection mechanism are used to understand the experimental results.