Nanoengineering of neuronal growth substrates
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Nanoengineering of neuronal growth substrates. Complex architecture of vertical and lateral micropatterns Polylysine, gelatin, Phospholipase A, or BSA. Template used for LBL-LO fabrication process. (a), (b)photolithography, (c) LbL assembly process, (d) LbL processed chips,

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Nanoengineering of neuronal growth substrates

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Nanoengineering of neuronal growth substrates

Nanoengineering of neuronal growth substrates

  • Complex architecture of vertical and lateral micropatterns

  • Polylysine, gelatin, Phospholipase A, or BSA


Template used for lbl lo fabrication process

Template used for LBL-LO fabrication process

  • (a), (b)photolithography, (c) LbL assembly process, (d) LbL processed chips,

  • (e) after lift-off, (f) top view of the fabricated chip: green-FITC labeled sPLA2, red-TRITC labeled BSA/PLL/gelatin.


Confocal scanning shows separate dye regions selective patterning of peptides

Confocal scanning shows separate dye regions: selective patterning of peptides

Biomacromolecules: 5: 1745, 2004.


Nanoengineering of neuronal growth substrates

  • Green squares have PLA (top 2) . Red squares (bottom) have BSA.


Nanoscale neuro coatings

Nanoscale neuro coatings

  • LbL layer by layer PEI+/Ln- onto Si. “Polyion glue”

  • Coatings need isoelectric pt. Away from neutral pH.

  • QCM to weigh layer, ELISA to assay Ln sites

  • Impedance spectroscopy

  • Reduce scarring & fibro-encapsulation?.

  • PEI is linear, CH is bulky

uncoated

[PEI-Ln]8

He, W. Biomaterials 26: 2983, 2005


Hearing sensitivity

Hearing sensitivity?

  • 100 hairs in a hair cell (inner) transduce bending

  • Outer hair cells are silent majority that bend actively for amplification of motion

  • High Speed of OHCs ?

  • Electromotility of OHCs – prestin: BW > 100 kHz (in vitro), but Cell membrane impedance filters @ 1Khz. I.e. time constant of V response….


Pushing on ohc with piezo

Pushing on OHC with piezo

Kennedy et al. Nature, 2005


Mech propertis of ohc

Mech Propertis of OHC

  • Negative stiffness = force generation


Force generation by ohc

Force generation by OHC

Kennedy et al. Nature, 2005


Role of ca

Role of Ca++


Boltzman model

Boltzman model

  • where P's are the probabilities of states or classes 1 and 2, and DF is free energy. For example Pi can represent the concentration of particles in 2 separate compartments. Lets say the energy in the first compartment is F1 and in the second, it is F2, and DF= F2-F1. Since the particles must either be in compartment 1 or 2, then P1 + P2 =1.


Nanoengineering of neuronal growth substrates

  • DPOAE level Ldp measured for EMF-exposure, i.e., within transmission pauses ~rhombuses!, and for sham exposure ~filled circles!, for one individual subject. Open circles indicate

  • the corresponding noise-floor level Lnoise . There were 12 different

  • tests where frequency f 2 and level L2 of the primary tones were varied. f 2

  • and L2 are indicated at the respective panels ~A!–~L!. Chosen case is representative

  • of the 24 subjects in whom the EMF-correlated change in DPOAE

  • level was smaller than 0.25


Measuring cochlear function

Measuring cochlear function

  • Distortion product otoacoustic emissions

  • Two tones given to ear: 2f1-f2 = best DPOAE

  • Most sensitive assay of cochlear function


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