exam2-2008soln-1 - Name Exam#2 BENG 434/ENAS 534...

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Name: Exam #2 BENG 434/ENAS 534 Biomaterials November 6, 2008 9:00-10:15 am Closed Book. No notes. Good luck. 1. Developing new materials for gene delivery. You join a company to develop non-viral vectors for gene delivery. You look around, and find some smart people and license their patents. David Lynn (U. Wisc.) developed a number of polymers for gene delivery. The starting materials are: O O O O H 2 N OH The acryl groups (double bonds on ends of the molecule on the left) can react with the amine on the molecule on the right to form: O N O O O OH n a. What kind of polymerization is used to make this polymer? (2 pts) CHAIN or STEP STEP b. How do you control molecular weight using this route? (4 pts) Stoichiometry c. Knowing the starting molecules and ending one, show how the attack might happen. (3 pts) The electrons on the amine attack the end of the double bond. d. You have a strong gut feeling that molecular weight is going to be important for transfection, so you decide to use GPC to characterize the polymer. i. What does GPC stand for? (2 pts) Gel permeation chromatography ii. How does GPC work? Draw a column, explain what comes out when and how the raw data is converted to molecular weight. (7 pts)
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Name: Essentially, one takes a polymer solution and injects it into a column with controlled flow (1 ml/min is common). The polymer column is backed with beads with different pore sizes (cross linked PS is common). The large molecules travel through the column quickly because they don’t fit or get entrapped in the pores. The smaller molecules do, and they come out later. It’s a size separation technique. One of the key aspects is that the polymer does not interact with the column so size is the only variable that effects time. DNA has an overall negative charge. The tertiary amine in this polymer has a positive charge. When the two are put together, they form a complex that condenses the DNA, making small particles that can be endocytosed. Once endocytosed, the complex sits in an endosome, where the pH drops from 7 to 5. The tertiary amines protonate, and the overall positive charge swells the polymer until the endosome ruptures. Then the DNA (hopefully) makes its way to the nucleus. e.
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exam2-2008soln-1 - Name Exam#2 BENG 434/ENAS 534...

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