o Growth/differentiation Peptide cytokines o Other potential functions Chemotaxis? gradients of peptide attractants What sizes are we talking about when we discuss peptides vs proteins? o Ideal case are peptides of -30 amino acids or less that can be prepared on a solid-phase synthesizer o This is usually more than adequate for adhesion peptides, enzyme-recognized peptides o Cytokines used on biomaterials may be slightly larger(30-60 amino acids total MW-5K g/mole), but may also be produced efficiently in mass quantities These peptides sometimes have some folding or intra-chain bonding that is not reproducible with shorter peptide sequences We'll discuss approaches to incorporating peptides in biomaterials as we go through the representative 1. cell adhesion 2. matrix remodeling 3. cytokine signaling Recognition of Biomaterials by Adhesion Receptors: Controlling cell Adhesion on Degradable Polymers Paradigm of Cellular responses to synthetic biomaterials Proteins adsorb(SLIDE) Cells respond to adsorbed protein layer o Why is this an issue? 1. Adsorbed layer often unstable and reconstructs as onment changes Vroman effect-> protein exchang 2. Cells may adhere poorly to this surface 3. Proteins denatured/presented in non-native conformations DRAW oN BOARD Non-native signals transmitted that are not readily controlled Immunogenic epitopes may be generated Lecture 3- Biological Recognition 8of15Lecture 3 – Biological Recognition 8 of 15 o Growth/differentiation ƒ Peptide cytokines o Other potential functions ƒ Chemotaxis?: gradients of peptide attractants • What sizes are we talking about when we discuss peptides vs. proteins? o Ideal case are peptides of ~30 amino acids or less that can be prepared on a solid-phase synthesizer o This is usually more than adequate for adhesion peptides, enzyme-recognized peptides o Cytokines used on biomaterials may be slightly larger (30-60 amino acids total MW~5K g/mole), but may also be produced efficiently in mass quantities ƒ These peptides sometimes have some folding or intra-chain bonding that is not reproducible with shorter peptide sequences • We’ll discuss approaches to incorporating peptides in biomaterials as we go through the representative applications: 1. adhesion 2. remodeling 3. ytokine signaling Recognition of Biomaterials by Adhesion Receptors: Controlling Cell Adhesion on Degradable Polymers Paradigm of Cellular responses to synthetic biomaterials • Proteins adsorb (SLIDE) • Cells respond to adsorbed protein layer o Why is this an issue? 1. Adsorbed layer often unstable and reconstructs as environment changes • Vroman effect -> protein exchange 2. Cells may adhere poorly to this surface 3. Proteins denatured/presented in non-native conformations DRAW ON BOARD • Non-native signals transmitted that are not readily controlled • Immunogenic epitopes may be generated cell matrix c