Filaments and four ordered structures inside a neuron fire a thousand times faster than the membrane: theory and experiment.

The current action potential paradigm considers that all components beneath the neuron membrane are inconsequential. Filamentary communication is less known to the ionic signal transmission; recently, we have proposed that the two are intimately linked through time domains. We modified the atom probe-connected dielectric resonance scanner to operate in two-time domains, milliseconds and microseconds simultaneously for the first time. We resonate the ions for imaging rather than neutralizing them as patch clamps do; resonant transmission images the ion flow 103 times faster than the existing methods. We revisited action potential-related events by scanning in and around the axon initial segment (AIS). Four ordered structures in the cytoskeletal filaments exchange energy ~250 µs before a neuron fires, editing spike-time-gap-key to the brain's cognition. We could stop firing above a threshold or initiate a fire by wirelessly pumping electromagnetic signals. We theoretically built AIS, whose simulated electromagnetic energy exchange matched the experiment. Thus far, the scanner could detect & link uncorrelated biological events unfolding over 106 orders in the time scale simultaneously. Our experimental findings support a new dielectric resonator model of neuron functioning in various time domains, thus suggesting the dynamic anatomy of electrical activity as information-rich.

Synthesis, characterization and cytocompatibility assessment of hydroxyapatite-polypyrrole composite coating synthesized through pulsed reverse electrochemical deposition.

Composite coating of hydroxyapatite-polypyrrole is synthesized with the help of pulsed reverse electrochemical deposition method from aqueous bath through in-situ formation and co-deposition of both phases simultaneously over metallic stainless steel surface. The inter phase bonding along with surface energy variation and morphology is tuned with the help of deposition current density, deposition time and reverse duty cycle. Hydroxyapatite (HA) lattice exhibits unidirectional growth along the highest atomic plane of 〈111〉 parallel to the coating surface. Different kind of deposited hydroxyapatite structures, namely lamellar and spherical particle scaffold, are observed at moderate and high current densities respectively together with the incorporation of polypyrrole (PPy) phase in between. Pyrrole ring stretching and bond strengthening represent the bonding with hydroxyapatite lattice, which in turn helps to increase the overall corrosion resistance of composite coating by ten-fold as compared to bare PPY coating. The coating deposited with moderate current density (10 mA/cm2) seems to be the optimum one regarding the faster-interconnected growth of MG63 cells over the coating surface along with highest corrosion resistance and anodic passivation capability. Presence of sub-micron level ceramic hydroxyapatite scaffold along with polymer filler material makes this composite biocompatible coating as a potential candidate to use over the load bearing metallic implant surfaces due to its sufficient elasticity along with superior toughness.

Excitonic dynamics of Chlorophyll-a molecules in chitosan hydrogel scaffold.

Biomimetic photo harvesting architecture has been proposed as an alternative for existing solar conversion systems. This fact led us to the successful realization of non-coherent electron hopping [hopping rate 4.28 ns(-1)] through excitonically coupled Chlorophyll-a (Chl-a) molecules within chitosan hydrogel matrix via TCSPC (Time Correlated Single Photon Count) and fluorescence anisotropy measurements. Chl-a molecules remain stable within the hydrogel matrix up to 3 months, as evidenced from UV-vis spectroscopy. The mono-exponential decay parameter with 78 picoseconds time scale, high initial anisotropy data [r0 = 0.33] and with reduced TCSPC lifetime [1.311 ns] of 23° in plane aligned Chl-a macrocycles, indicate that hopping excitonic cascade is prominent among chlorophyll molecules. From the Raman Spectra, it can be postulated that they form a highly co-ordinated closely packed structure via water molecules within chitosan hydrogel due to 6th co-ordination through central Mg of porphyrin macrocycle. All these data predict that this chlorophyll-chitosan hydrogel can be an active component in artificial light harvesting systems.