BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 Lecture 10: Bioengineering applications of hydrogels: Molecular Imprinting and Drug Delivery Last Day polyelectrolyte gels Polyelectrolyte complexes and multilayers Applications in bioengineering Theory of ionic gel swelling Toda Molecular imprinting ug Supplementary Reading: S.R. Lustig and N.A. Peppas, Solute diffusion in swollen membranes. IX Scaling laws for solute diffusion in gels, J. App/. Polym. Sci. 36, 735-747(1988) T. Canal and N A. Peppas, "Correlation between mesh size and equilibrium degree of swelling of polymeric networks, J. Biomed Mater Res 23, 1183-1193 (1989) Molecular Imprinting oncepts of molecular imprinting Molecular imprinting is the design of polymer networks that can recognize a given target molecule and bind it preferentially in the presence of an excess of irrelevant molecules, some of which may have very similar molecular structures o Seeks to mimic specificity in biological recognition obtained through protein-protein interactions Steps to the preparation of molecularly-imprinted networks 1. mixing of binding monomers and target molecule o target can be mixed directly with liquid monomers in bulk or co-dissolved in a non-interfering solvent o monomers bind target non-covalent bonding metal coordination o mixture usually at high concentration(e.g. 50%W/vol solutions): enforces close interactions of target with binding monomers and leads to a tight network that holds the position of functional groups in position of template binding 2. polymerization of monomers in place sually photopolymerization(rapidly 'trap structure) 3. washing for removal of target molecule from network pockets Lecture 10-Bioengineering Applications of Hydrogels 1of12
BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 Lecture 10: Bioengineering applications of hydrogels: Molecular Imprinting and Drug Delivery Last Day: polyelectrolyte gels Polyelectrolyte complexes and multilayers Applications in bioengineering Theory of ionic gel swelling Today: Molecular imprinting Hydrogels in drug delivery Supplementary Reading: S.R. Lustig and N.A. Peppas, ‘Solute diffusion in swollen membranes. IX. Scaling laws for solute diffusion in gels,’ J. Appl. Polym. Sci. 36, 735-747 (1988) T. Canal and N.A. Peppas, ‘Correlation between mesh size and equilibrium degree of swelling of polymeric networks,’ J. Biomed. Mater. Res. 23, 1183-1193 (1989) Molecular Imprinting1,2 Concepts of molecular imprinting • Molecular imprinting is the design of polymer networks that can recognize a given target molecule and bind it preferentially in the presence of an excess of irrelevant molecules, some of which may have very similar molecular structures o Seeks to mimic specificity in biological recognition obtained through protein-protein interactions • Steps to the preparation of molecularly-imprinted networks: 1. mixing of binding monomers and target molecule o target can be mixed directly with liquid monomers in bulk or co-dissolved in a non-interfering solvent o monomers bind target covalent interactions non-covalent bonding metal coordination o mixture usually at high concentration (e.g. 50% w/vol solutions): enforces close interactions of target with binding monomers and leads to a tight network that holds the position of functional groups in position of template binding 2. polymerization of monomers in place o usually photopolymerization (rapidly ‘trap’ structure) 3. washing for removal of target molecule from network pockets Lecture 10 – Bioengineering Applications of Hydrogels 1 of 12
BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 salyze Recognitive Prole Lectins fe Biemdlewle iie amino aed residues Biomolecule imvolved in specifie recognition) t Choos or Desien Reooemtive Polymer Syntess Resdue functional t D Wash 8武一 二冒生品 types of target molecules: 1 o small-molecule drugs o steroids o nucleic acids o amino acids o metal ions o proteins Structure of Molecularly-Imprinted Networks structure of molecularly-imprinted networks o imprinted networks can be confined to a thin surface layer or prepared in bulk o surface networks usually perform better for capture of large molecules like proteins simple synthetic components for recognition networks o monomers o itaconic acid o acrylamides 4-vinyl pyrrolidone o other designed mo cross-linker o ethylene glycol dimethacrylate o PEG dimethacrylate o 'chain effect o binding of monomers to macromolecular templates causes a reduction in chain termination and thus an overall increase in reaction rate Example of molecular recognition: molecular imprinting of D-glucose(Peppas) o Monomers chosen as analogs of the amino acid residues that bind to glucose in vivo O WHAT RECEPTORS BIND GLUCOSE? Aspartate Lecture 10-Bioengineering Applications of Hydrogels 20f12
BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 • types of target molecules: 1 o small-molecule drugs o steroids o nucleic acids o amino acids o metal ions o proteins Structure of Molecularly-Imprinted Networks • structure of molecularly-imprinted networks o imprinted networks can be confined to a thin surface layer or prepared in bulk o surface networks usually perform better for capture of large molecules like proteins • simple synthetic components for recognition networks o monomers: o methacrylic acid o itaconic acid o acrylamides o 4-vinyl pyrrolidone o β-cyclodextrin o other designed monomers o cross-linkers o ethylene glycol dimethacrylate o PEG dimethacrylate o ‘chain effect’3 o binding of monomers to macromolecular templates causes a reduction in chain termination and thus an overall increase in reaction rate • Example of molecular recognition: molecular imprinting of D-glucose (Peppas) o Monomers chosen as analogs of the amino acid residues that bind to glucose in vivo: o WHAT RECEPTORS BIND GLUCOSE? • Aspartate Lecture 10 – Bioengineering Applications of Hydrogels 2 of 12
BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 o Draw structures on board o Simple synthetic monomers chosen to mimic the bonding interactions of these amino acids Hydroxyethyl methacrylate CH CH- OCH Acrylic acid TARGET: D-glucose Specificity of binding sues. 0.8 Tightly cross-linked networks hold functional group positions for better Bound 0 45 mu bound g cry polymer recognition but restrict entry of target into network 30 40 50 60 Limited complexity in recognition units Time(hrs) c时出 copolymers6 C贴 Mnomn.Fayme i wear:Ar把过用20 MA Copolymers wth67% Competive substrate pntd intensiy Nonimprinted intensity 3±11.81 5097±07 81±1383585 Flores Fluorescent analogue 5657±090 Improving recognition by surface templating(Ratner+5) o Protein adsorbed to mica surface, coated with disaccharide, then coated with C3 Fs film by radiofrequency glow-discharge plasma treatment o Sugar coating protects protein from denaturation on dehydration Lecture 10-Bioengineering Applications of Hydrogels 3of12
BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 • Glutamate • Asparagines • Serine o Draw structures on board o Simple synthetic monomers chosen to mimic the bonding interactions of these amino acids: QuickTime™ and a Graphics decompressor are needed to see this picture. TARGET: D-glucose Hydroxyethyl methacrylate Acrylic acid acrylamide Specificity of binding: Issues: Tightly cross-linked networks hold functional group positions for better recognition but restrict entry of target into network Limited complexity in recognition units • Improving recognition by surface templating (Ratner 4,5) o Protein adsorbed to mica surface, coated with disaccharide, then coated with C3F6 film by radiofrequency glow-discharge plasma treatment o Sugar coating protects protein from denaturation on dehydration Lecture 10 – Bioengineering Applications of Hydrogels 3 of 12
BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 HOCH 2H2 Trehalose(disaccharide) 是 pen es ad noted or p hash cbs ed ie nd ated prornt arace b. a tapia mom m mo of the t phomphstebufned asine CPHS. PH I4 A I-tom a drawing of tbnnogn. e Mechanims br the poc -6mn deming a 1-30nm fuoropoyner bocaue ots ma an ora song intact onc e回智doto The suing o Resulting recognition LSZ RNase LSZ IMP02±0.083 201-△ RNase IMp40±060 LSZ/RNese ratio LSZ in solution can exchange with LSZ= lysozyme imprinted LSZ, but Rnase cannot displace LSZ on surface o Utilizing in-situ formability of photopolymerized hydrogels for lab-on-a-chip applications o Photopolymerized Bulk templates(Peppas) Lecture 10-Bioengineering Applications of Hydrogels 4of12
BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 Trehalose (disaccharide) o Resulting recognition: LSZ RNase LSZ in solution can exchange with LSZ = lysozyme imprinted LSZ, but Rnase cannot displace LSZ on surface o Utilizing in-situ formability of photopolymerized hydrogels for lab-on-a-chip applications o Photopolymerized Bulk templates (Peppas): Lecture 10 – Bioengineering Applications of Hydrogels 4 of 12
BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 Silicon substrate Surface treated with organosilane Monomer applied agent to nduce bonding treated silicon substrate asked UV polymerization Mkregutterne pelynt 二, o Plasma-deposited surface templates patterned by microcontact printing(Ratner) PDMS stamp m o nm vidn (SA)n P8S ndw aber rinse Imprint surtace for -5s transterring a monolayer of streptawd in to mca ony tod mgons The m ca surface was then exposed to a bumin(BSA)n Fas. 10 ITImI baind i h w th a soon of botn BsA labeled with t0-nm lodai gold to Lecture 10-Bioengineering Applications of Hydrogels 5of12
BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 o Plasma-deposited surface templates patterned by microcontact printing (Ratner): Lecture 10 – Bioengineering Applications of Hydrogels 5 of 12