Download Slide 1

Intelligent Biomaterials
Protein Delivery
Molecular Imprinting and Micropatterning
Nicholas A. Peppas
Our Laboratories
• 22 Researchers
– 12 Ph.D. students (8 ChEs, 4 BMEs)
– 3 Visiting scientists (Italy)
– 1 Technician
– 6 Undegraduate students
• About 3,800 sq.ft. facilities
• Modern equipment including cellular facilities
• Budget of about $ 2M
• Grants from NIH, NSF, industry
The Changing World of Biomaterials,
Drug Delivery and Biomolecular Engineering
• Formation and fabrication of supramolecular
assemblies comprising natural biological elements,
structures or membranes.
• Synthesis and preparation of modified biological
molecules
• Biomolecules as the basis of nanostructures,
molecular adhesives
• Micropatterned and microfabricated arrays
Oral protein delivery
Oral Delivery of Proteins
“Oral delivery of peptides and proteins has long been dubbed the ‘Holy Grail’ of drug
delivery…”
Why?
• Increase patient compliance
and comfort over other
forms of drug delivery (i.e.
injection)
• Mimic physiologic delivery
of proteins
• Simple administration
• Reduce costs
• Potentially improve efficacy
Challenges of Oral Protein Delivery
GI Tract is designed to digest proteins and food.
1. Protect the drug
– Acidic environment in the stomach
– Proteolytic enzymes in the GI tract
2. Improve bioavailability
– Increase drug transport across intestinal
epithelium
– Localize drug at targeted site of
absorption
3. Maintain biologically active and stable
drug
Transport for Oral Drug Absorption
Transport Mechanism
a. Transcellular pathway
b. Paracellular pathway
c. Transcytosis and
receptor-mediated
endocytosis
d. Lymphatic absorption
through M cells
e. P-glycoprotein efflux
(not shown)
Factors Affecting Transport
1. Molecular mass of drug
2. Drug solubility
In Vivo Study with pH-Responsive
Complexation Hydrogels
• P(MAA-g-EG)
microspheres loaded
with insulin
• Administered to
diabetic rats 40%
drop in blood glucose
levels
• Prior work done by
Tony Lowman
Carrier Mediated
Goal: Protect drug in the GI tract and be absorbed
with drug by epithelial layer.
• Biodegradable polymers,
lectin modified carriers
• Sites of uptake
1. M cells (majority of uptake)
2. Transcellular
3. Paracellular
• Poor particle absorption
Florence, A. T. The oral absorption of micro- and nanoparticulates: neither exceptional nor unusual. Pharm Res 1997, 3, 259-266.
Mucoadhesion
Upper small Intestine
Stomach
Decomplexation
Mucosa
Mucosa
Blood Glucose Response in
Healthy and Diabetic Wistar Rats
140
Healthy Animal
Diabetic Animal
Serum Glucose
(% of Initial Level)
120
100
80
60
40
0
2
4
Time t, (h)
6
8
Systemic Circulation
Tight
Junction
Polymeric
Carrier
Protein
Proteolitic
Enzymes
Mucosa
Caco-2 Cells as GI Model
• Advantages
– Spontaneously
differentiate
– Produce enzymes
– Posses tight
junctions
– Develop microvilii
– Transport of
inorganic
molecules
correlates well with
Nanodevices of Intelligent Gels
for Protein Release
I
GOx
I
GOx
Empty hydrogel absorbs glucose
leading to gluconic acid production
I
I
I
G
G
GOx
I
I
GOx
G
GlucA
I
G
I
G
GlucA
G
I
GlucA
G
GOx
GlucA
GOx
G
I
G
GlucA
I
G
Decrease in pH leads to gel expansion
which releases insulin
Targetting and
Nanotechnology
• Targeted delivery for cancer therapy
• Gene delivery
• Long term treatment of chronic
diseases
BioMEMS Sensor Platform
• Pattern environmentally responsive hydrogels
onto silicon microcantilevers to create a
BioMEMS/MEMS sensor device.
Polymer
Silicon
Laser
beam
Laser
beam
θ
φ
φ>θ
Change in pH, temperature, etc. 
hydrogel swells
Experimental Procedure
• Surface Modification
OH
OH
OH
OH
OH
OH
OH
REACTIVE SITES
OH
O
OO
Si
O
Si
O
O
O
O
Si
O
O
O
O
O
Si
Si
O
O
O
O
O
O
Si
O
Provides
inorganic/organic
interface
Organosilane (-MPS) Surface Treatment
• Micropatterning
Silicon substrate
Surface treated with organosilane
agent to induce bonding
Monomer applied to
treated silicon substrate
UV light
Photomask
Masked UV polymerization
Micropatterned polymer
bonded on silicon substrate
Micropatterned Hydrogel on
Silicon Microcantilever
Silicon cantilever
Etched well
• Volume shrunk as the
polymerization proceeded
Silicon cantilever
• Polymer adhered to
silicon surface and could
not shrink at the interface,
resulting in stress
formation in the polymer
film
Polymer
A)
100 mm
B)
100 mm
• This stress in the polymer
film resulted in bending
the microcantilever
Top view images obtained utilizing an optical microscope in Nomarski mode showing a
silicon microcantilever patterned with an environmentally responsive hydrogel. In A), the
focus is on the substrate, while in B), the focus is on the microcantilever tip. Profilometry
indicated that the thickness of the patterned hydrogel is approximately 2.2 mm.
Confocal Images of Microarrays
Acrylamide-PEG200DMA with 67% Crosslinking Ratio
50 mm
3D Projection of micropatterned recatangular array of a biorecognitive networks obtained
utilizing a confocal microscope. Profilometry indicated that the thickness of the
micropatterns are approximately 13 mm.
Optical and Confocal Images of Micropatterns
Acrylamide-PEG200DMA with 67% Crosslinking Ratio
Microcantilever Shape
A)
Silicon
B) Control
C) Recognitive
Polymer
50 mm
25 mm
25 mm
Images of micropatterned biorecognitive networks. In A), an optical image (Nomarski mode)
of recognitive network patterned in shape of cantilever is demonstrated. In B) and C), a
confocal microscope slice through middle cantilever pattern of a control and recognitive
network, respectively, are shown.
Profilometry indicated that the thickness of the
micropatterns are approximately 13 mm.