1. Group Presentation #2
Craig Milroy
(4/29/10)

2. (I) Py-HA electrode coating
Objective: increase in vivo longevity of neural probes by minimizing glial scarring & general immune response.
so far: coat Py-HA on electrochemically active portion of electrode surface implant evaluate immune response.
(www.

3. (I) Py-HA electrode coating
next steps:
(1) GM-HA or GM-heparin coating (UV polymerization) of entire probe surface, including electrode sites and non-conducting parts (Leach protocol).
(2) incorporate anti-inflammatory drug release.
(www.

4. Diffusionbased
(2) Biodegrable conjugated matrix
(3) Electro-stimulated release

5. (I) Py-HA electrode coating
Delivering anti-inflammatory agents
(1) Diffusion of nanoparticles
(GM)HA + poly-aspirin nanoparticles (or layers)
(2) Biodegradable gel-matrix containing drugs
(Mix GMHA with) HA-polyaspirin conjugate
(3) Enzyme-mediated release
Ppy doped with aspirin, coated with PyHA, GMHA, etc.
(a) oxidoreductase enzymes mediate (b) electron transfer to Ppy & (c) convert ox. Ppy to re. Ppy, causing (d) release of doped aspirin.
NHS-EDF chemistry, potentially use aprotic solvents such as DMSO, DMF, in this case, need to replace Na w/ TEA or TBA

6. Selection of anti-inflammatory agents
For doping / nanoparticles
Mw of polymer
Solubility, degrad. rate
Reaction efficiency (solvent, yield)
Degrad. rate
For conjugation with HA
mycobacteria
colon inflammation, ulcerative collitus
Uhrich, Biomacromolecules 2005, 6,

7. Key steps for “diffusion-based”
Disperse poly(aspirin) nanoparticles in GMHA prior to crosslinking
MW- dependent water solubility.
Loading requirements/limitations.
Characterize release profile
MW-dependent diffusivity of polyaspirin.
swelling characteristics of gel.

8. (Leach, Schmidt. Mat Res soc symp proc Vol EXS-1, 2004)
GMHA
(Leach, Schmidt. Mat Res soc symp proc Vol EXS-1, 2004)

9. Electrochemically mediated release
Fundamental hurdle: identify relevant enzyme
ascorbate peroxidase: REDUCES H2O2 (transfers electrons from ascorbate to peroxide, producing dehydroascorbate and water as products)
horseradish peroxidase:
H2O2 + 2AH2 HRP C 2H2O + 2AH*
Involves both oxidation and reduction, but generation of reactive species as well

10. IDEAS……. Implantable electrode/biosensor platform
Enzyme specific for NO from activated astrocytes?
Direct reduction of doped Ppy?
Tethered enzyme?
Use of melanin?

11. Entrapped enzyme
(2) Tethered enzyme

12. (II) PLGA meshes
Objective: introduce nanoscale surface features on biomimetic materials to optimize cell-material interactions.
so far: coating PLGA mesh with Py, amino-Py, and carboxy-Py; electro-stimulation, cell fixing/staining, visualization.
next steps: bioactive molecule conjugation (laminin, fibronectin), melanin.
other applications:
coating Py on other polymers (e.g. polysulfone, cellulose acetate) for surface oxidation to prevent biofouling.

13. (III) PPy-PU
Background: restore function to damaged myocardium; skeletal myoblasts do not electrically couple with mycocardium and do not express connexin.
Objective: synthesize electrically conductive elastomer to enable propagation of cardiac electrical signals across damaged gap junction.
so far: emulsion polymerization (Py in-situ within PU), cyto-compatible, amorphous (Chris Broda, Benjamin Harrison).
Wang Y, GA Sotzing, RA Weiss. “Preparation of conductive Py-PU composite foams by in- situ polymerization of Py”. Chemistry of Materials 20:7 (2008);

14. (III) PPy-PU
next steps…polymer processing to achieve: fibrous form (electrospinning, injection, extrusion)
porous form (gas bubbling, salt leaching)
for cardiac/neural application (potential Will Wagner collab.)

15. (IV) OTHERS…..
extensions of Natalia’s or Jessica’s projects (organic-inorganic materials interface)
systems analysis of cell behavior
melanin
biodegradable scaffolds (with new post-doc)?

17. ORGANIC-INORGANIC INTERFACES
Speaker:  Andrew Dattelbaum Technical Staff Member, Center for Integrated Nanotechnologies, Los Alamos National Laboratory
Title:  Luminescent Silica Nanocomposite Materials for Biological Sensing and Imaging
Abstract:   Luminescent nanocomposite silica materials may be used in a variety of sensing and imaging applications.  Silica is an ideal matrix for fluorescence applications because it is optically transparent and provides a rigid, chemically inert framework that acts to protect and immobilize sensing materials. Several examples will be presented of how nanocomposite silica materials can be applied for sensing of proteins in solution or imaging in cells.  In particular, the talk will focus on 1) the preparation and characterization of bulk single-walled carbon nanotube silica composite materials for biosensing applications and 2) functionalized silica-based nanoparticles for far-red-to-near infrared fluorescence imaging in cells. For this work, the use of various fluorescence and spectroscopic techniques will be discussed, including Raman and fluorescence spectroscopy as well as confocal and wide-field imaging techniques, to characterize the nanocomposite silica materials.

18. (III) Electrode Studies
mount electroactive PyHA gel on electrode surface (carbon paste, ITO)
i) so far:
ii) electrochemical biosensors
immobilize enzymes within hydrogel (Giuseppe-Elie)
connect to metal electrode via PPy redox mediators.
p(HEMA) for gel, copolymerized with phosphoylcholine (PC) and PEG for biocompatibility,
Enzyme and mediator tethered by “monomerization” reactions with acryloyl(PEG) NHS ester that links lysine residues in
PPy for “interference shielding”