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Intelligent BiomaterialsIntelligent BiomaterialsProtein Delivery Protein Delivery
Molecular Imprinting and MicropatterningMolecular Imprinting and Micropatterning
Nicholas A. Peppas
Our LaboratoriesOur 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, The Changing World of Biomaterials, Drug Delivery and Biomolecular EngineeringDrug 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 deliveryOral protein delivery
Oral Delivery of ProteinsOral Delivery of Proteins
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
“Oral delivery of peptides and proteins has long been dubbed the ‘Holy Grail’ of drug delivery…”
Challenges of Oral Protein DeliveryChallenges of Oral Protein Delivery
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
GI Tract is designed to digest proteins and food.
Transport for Oral Drug AbsorptionTransport for Oral Drug AbsorptionTransport 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 VivoIn Vivo Study with pH-Responsive Study with pH-Responsive Complexation HydrogelsComplexation 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 MediatedCarrier Mediated
• Biodegradable polymers, lectin modified carriers
• Sites of uptake1. M cells (majority of uptake)
2. Transcellular
3. Paracellular
• Poor particle absorption
Goal: Protect drug in the GI tract and be absorbed with drug by epithelial layer.
Florence, A. T. The oral absorption of micro- and nanoparticulates: neither exceptional nor unusual. Pharm Res 1997, 3, 259-266.
MucoadhesionMucoadhesion
Mucosa Mucosa
Decomplexation
Stomach Upper small Intestine
Blood Glucose Response in Healthy and Diabetic Wistar Rats
40
60
80
100
120
140
0 2 4 6 8
Healthy Animal
Diabetic Animal
Serum Glucose (% of Initial Level)
Time t, (h)
Systemic Circulation
Polymeric Carrier
TightJunction
Mucosa
Protein
ProteoliticEnzymes
Caco-2 Cells as GI ModelCaco-2 Cells as GI Model Caco-2 Cells as GI ModelCaco-2 Cells as GI Model
• Advantages
– Spontaneously differentiate– Produce enzymes– Posses tight junctions– Develop microvilii– Transport of inorganic
molecules correlates well with the in vivo absorption
• Disadvantages
– Do not produce mucus– The properties are
determined by the passage number
Nanodevices of Intelligent GelsNanodevices of Intelligent Gelsfor Protein Releasefor Protein Release
GOx
GOx
GlucA
GOx
GOxG
Empty hydrogel absorbs glucoseleading to gluconic acid production
Decrease in pH leads to gel expansionwhich releases insulin
G
G
G
GGGlucA
GlucAGOx
GOx
G
G
G
GGlucA
GlucA
I
I I
I
II
I I
I
I
II
Targetting and Targetting and NanotechnologyNanotechnology
• Targeted delivery for cancer therapy
• Gene delivery
• Long term treatment of chronic diseases
BioMEMS Sensor PlatformBioMEMS Sensor Platform
• Pattern environmentally responsive hydrogels onto silicon microcantilevers to
create a BioMEMS/MEMS sensor device.
Laser beam
θ
Polymer
Silicon
φ > θ
Laser beam
φ
Change in pH, temperature, etc. hydrogel swells
Experimental ProcedureExperimental Procedure
• Surface Modification
• Micropatterning
Organosilane (?- )MPS Surface Treatment
OHOH
OHOH
OHOHOH
OH
O
Si
O
OO
OO
OOOO
O
Si
OO
Si
OO
Si
OO
Si
O
O
Si
O
REACTIVE SITES
Provides inorganic/organic interface
Organosilane ( ?-MPS) Surface Treatment
OHOH
OHOH
OHOHOH
OH
O
Si
O
OO
OO
OOOO
O
Si
OO
Si
OO
Si
OO
Si
O
O
Si
O
REACTIVE SITES
Provides inorganic/organic interface
OHOH
OHOH
OHOHOH
OHOH
OHOH
OHOH
OHOHOH
O
Si
O
OO
OO
OOOO
O
Si
OO
Si
OO
Si
OO
Si
O
O
Si
OO
Si
O
OO
OO
OOOO
O
Si
OO
Si
OO
Si
OO
Si
O
O
Si
O
REACTIVE SITES
Provides inorganic/organic interface
Provides inorganic/organic interface
Silicon substrateSurface treated with organosilane
agent to induce bondingMonomer applied to
treated silicon substrate
Micropatterned polymer bonded on silicon substrate
UV light
Photomask
Masked UV polymerization
Silicon substrateSurface treated with organosilane
agent to induce bonding
Silicon substrateSurface treated with organosilane
agent to induce bondingMonomer applied to
treated silicon substrateMonomer applied to
treated silicon substrate
Micropatterned polymer bonded on silicon substrate
Micropatterned polymer bonded on silicon substrate
UV light
Photomask
Masked UV polymerization
UV light
Photomask
Masked UV polymerization
Micropatterned Hydrogel on Micropatterned Hydrogel on Silicon MicrocantileverSilicon 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 m.
100 ? m 100 ? m
Silicon cantilever
Polymer
Silicon cantilever Etched well • Volume shrunk as the
polymerization proceeded
• Polymer adhered to silicon surface and could not shrink at the interface, resulting in stress formation in the polymer film
• This stress in the polymer film resulted in bending the microcantilever
A) B)
Confocal Images of MicroarraysConfocal Images of MicroarraysAcrylamide-PEG200DMA with 67% Crosslinking RatioAcrylamide-PEG200DMA with 67% Crosslinking Ratio
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 m.
50 m
Optical and Confocal Images ofOptical and Confocal Images of MicropatternsMicropatternsAcrylamide-PEG200DMA with 67% Crosslinking RatioAcrylamide-PEG200DMA with 67% Crosslinking Ratio
Microcantilever ShapeMicrocantilever Shape
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 m.
25 m 25 m
RecognitiveControl
50 m
SiliconPolymerA)
B) C)