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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.