Pyrrole-hyaluronic acid conjugate for Pyrrole-hyaluronic acid conjugate for neural probe, stents, and sensor neural probe, stents, and sensor

applicationsapplications

Jae Y Lee and Christine E Schmidt

June 19, 2009

Implantable electrodes• Loss of electrical sensitivity

-Increase in impedance-Highly sensitive electrodes are required

•Nerve tissue reaction - Acute and chronic responses - Foreign body reaction - Glial scar tissue formation

GFAP-stained (3 weeks) b)

Neural electrodes a)

a) J Neural Eng 2007 Williams CJ et al. b) Biomaterials 2003 Cui X et al..

• Electrochemical deposition of HA on conductive materials - Electrically conductive - Cytocompatible - Stable - Hydrophilic - Resistant to protein fouling and cell adhesion

Technology and properties

Electrochemical coating process

0 – 1.0 V (vs SCE)

Conductive substrate or electrode (e.g., ITO, PPy)

Reference electrode (SCE)

Counter electrode (Pt mesh)

Working electrode (ITO)

PyHA solution

Stable HA coating

HA coating solution

Bare ITO BorderHA caoted ITO

ITO HA-coated ITO

Surface characterization

Bare ITO HA-coated ITO

•Immunostaining of HA using bHABP, followed by PE-streptavidin

• Water contact angle measurement

Electrochemical Impedance Spectroscopy (EIS)

Electrical properties of uncoated and HA-coated ITO are the same

1 10 100 1000 10000 10000010

100

1000

10000

100000

HA

-coa

ted

ITO

Frequency (Hz)

HA-coated ITO Bare ITO

In vitro astrocyte culture

Immunostaining three days in culture

• scale bars = 50 µm

• GFAP (green), DAPI (blue), HA (red)

HA-coated ITO HAase-treated

Bare ITO

HA-coated area

Unmodified area

90 days

10 days

Long-term culture

•Images were taken at the same location for all time points. •Scale bars are 50 µm