Tracey Atkinson, Patrick Steiner, Low Rui Hao, and Lim Yao Chong

Spider Dragline Silk  Spider web material that makes up the main “axels” of orb weaver spider webs  High tensile strength and very extensible

Structure of Spider Silk  Has a composite structure: 20% crystalline regions 80% highly elastic substances  Extendible regions connect crystalline regions to produce the amazing properties of spider silk

Applications of Spider Silk  Range from biomedical uses, like ligaments and sutures, to bullet proof vests and parachutes  Spider silk is not used because it is not readily available and there is no method to mass produce it

Project Objective To create a material with both high tensile strength and elasticity by mimicking the composite structure of spider silk. Hypothesis By combining the optimal electrospinning method and optimal ratio of keratin and elastin, we can create a composite mat with high tensile strength and extensibility comparable to that of spider dragline silk.

Keratin and Elastin Keratin: a material that provides strength in biomaterials such as nails, bird beaks, horns, etc. Biodegradable Has same beta-sheet composition as spider silk Elastin : A material that provides elasticity to artery walls, lung tissue, skin, ligaments, etc. Biodegradable More elastic than spider silk

Electrospinning A polymer is dissolved and placed in a syringe The solution is charged with a high voltage The high voltage creates an electric field that causes the polymer to be spun out in thin threads to a collector plate A fibrous mat is formed

Methodology  Part 1 AOS: optimize the spinning of keratin and elastin separately HCI: verify the AOS results after break  Part 2 AOS: determine the best method for combining keratin and elastin HCI: determine the best ratio of elastin to keratin

Part 1  Optimize the conditions for electrospinning keratin and elastin individually Voltage Solvents Flow rate Distance to collector plate  The optimal conditions found will be kept constant in Part 2 of the experiment

AOS  Will try multiple variations on electrospinning, while keeping the ratio of elastin to keratin constant, to produce the material with properties most similar to spider silk  Will use a consistent ratio of elastin to keratin yet to be determined

AOS-Variables Independent variable: Method for combining elastin and keratin Dependent variable: Tensile strength and extensibility of fibrous mat. Control Variables(constants): Ratio of elastin to keratin, concentration of separate polymer solutions, voltage, flow rate and distance from the collector plate.

AOS Method 1  The syringes will be placed on opposing sides of a rotating collector plate  Has been found to produce homegenous mats of multiple polymers

AOS Method 2  The syringes will be placed on the same side of a stationary collector plate

AOS Method 3  We will attempt to mix the polymers in one solution, and spin them from the same syringe  Will be attempted if keratin and elastin can be put into the same solution

HCI  Will vary the ratio of elastin to keratin, while keeping method constant, to produce the properties most similar to that of spider silk  Will use AOS Method 2(parallel syringes) for all tests

HCI-Variables Independent variable: Ratio of volume of Keratin solution to Elastin solution used during electrospinning. Dependent variable: Tensile Strength and Extensibility of Fibrous mat. Control Variables(constants): Method of electrospinning, concentration of separate polymer solutions, voltage, flow rate and distance from the collector plate.

AOS: Optimizing Concentration, Flow Rate, Voltage and Solvent for electrospinning Keratin & Elastin HCI: Duplicating results with a smaller range of independent variables AOS: Vary Methods of electrospinning HCI: Vary Ratio of volume of keratin to elastin solution during electrospinning. Carry out electrospinning with 5 extreme and sparse ratios (Independent Variable). Measure Tensile strength and Extensibility of results (Data) by sending fibrous mats to NUS. From data collected, extrapolate the approximate range of optimal ratio. Carry out electrospinning for the approximate range. Measure Tensile strength and Extensibility of results (Data) by sending fibrous mats to NUS Optimal Ratio is found. Most suitable method is found. Combine both optimal ratio & most suitable method to create a fibrous mat that could mimic spider dragline silk

Timeline November to January Optimize the conditions for electrospinning keratin and elastin February to April Test the different methods of combining elastin and keratin April to June Finalize results and send for tensile testing January to February Verify the optimal conditions for spinning keratin and elastin separately March to July Find the optimal ratio for combining elastin and keratin July to August Send for tensile testing and finalize results

Combining Results  If results for ratio are found early enough, the optimal method and optimal ratio will be combined in one final test to see if we were successful in mimicking spider silk