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Briefly explain why heterobifunctional linkers are preferable compared to homobifunctional linkers when conjugating a biomolecule to a tissue engineering scaffold surface:

In lecture, an example was shown and discussed that showed a greater percentage of cells with well-defined stress fibers on surfaces where peptides (of the same type) were conjugated to surfaces using star PEG (where more than one peptide was conjugated per PEG tether) rather than one-arm PEG (where only 1 peptide was conjugated per PEG tether), but the total peptide density was the same in both conditions.  What most likely contributed to the increase in well-formed stress fibers?  

Given the information in the previous questions regarding contact angle and the bioactivity of adsorbed proteins on each surface,  infer the relative amount of cell adhesion (in terms of number of cells adhered as lowest, highest, moderate/in the middle) you expect on each surface and EXPLAIN briefly why.   In your answer, please list A, B, and C with a specific answer for each. A –   B –   C –

According to Gibbs Law of free energy:  ∆G = ∆H – T(∆ S)  In order for protein adsorption to occur spontaneously, ∆G must be a positive number.

List 2 reasons why we want scaffolds to degrade in tissue engineering.  Also, name 2 ways properties of a scaffold may change as it degrades.  

The images below show MSCs on two different surfaces (A and B).  Which material is more favorable for MSC adhesion?  Explain two reasons why you can conclude this.   

During human embryonic development, the notochord goes on to become the brain and spinal cord.

Alginate is a natural polysaccharide material that forms a very hydrophilic hydrogel that resists protein adsorption, yet due to being a natural material, mammalian cells will recognize it directly.

Jackson has experienced a stroke. He is found to have left hemiparesis (weakness on the left side of the body). He is also having difficulty perceiving vibration on the left side of his body. He can speak clearly and is able to respond to complicated verbal commands. Based on the physical exam findings, what specific area(s) of Jackson’s brain have been damaged as a result of his stroke? [Answer in 2-4 sentences]. 

In the micturition reflex urine is actively expelled from the bladder (smooth muscle). The postganglionic neuron releases acetylcholine, which binds to muscarinic receptors and causes the bladder muscle to contract. In someone who experiences urine leakage (incontinence) would you administer a muscarinic antagonist or agonist. Explain your reasoning.