Biomaterials

Provide ALL answers in typed format. The response for each question should be no longer than 1 typed page (11pt font minimum). 1. [25pts total] You are designing a scaffold for bone tissue engineering. You have modified a polymer with two different surface treatments (A and B). You then seed equal number of osteoblasts (bone-forming cells) on discs of the samples with the two different surface modifications. After 2 weeks, you perform two assays: i) Calcium production, which is done by adding a reagent that reacts with calcium to produce a color and reading the absorbance at 650 nm. You also run standards at 650 nm for comparison, using the principles of Beer-Lambert’s law. The standards and the experimental results are found below: Standards: Calcium (ug) Absorbance (arbitrary units) 0 0.12 1.56 0.15 3.125 0.22 6.25 0.35 12.5 0.52 25 0.79 50 1.31 100 2.49 Experimental results: A absorbance = 0.88 B absorbance = 0.26 ii) DNA content (an indicator of cell number), which is done by adding a reagent that reacts with DNA to produce a signal and reading the absorbance at 530 nm. You also run standards at 530 nm for comparison, using the principles of Beer-Lambert’s law. The standards and the experimental results are found below: DNA (pg) Absorbance (arbitrary units) 0 0.1 1.5 0.32 3 0.72 6.25 1.31 12.5 2.12 Experimental results: A absorbance = 0.93 B absorbance = 0.86 BME 318: Biomaterials Fall 2015 Homework Set 3: DUE 11/16/15 at 4:30pm a. [15pts] Using the raw data, determine how much calcium and DNA (an indicator of cell #) is present on each sample after two weeks. MUST SHOW ALL WORK (this includes any graphs and trendline equations) b. [5pts] Based on your calculations above, which surface modification technique would be better for greater bone formation in the body – A or B? c. [5pts] You now want to modify the surface to improve osteoblast migration. Which cellular function should you target (why) and describe what type of modification you will incorporate? You should justify your answer in the context of the intended application (bone tissue engineering). 2. [25pts total] Refer to the attached article by van Putten et al. to respond to the questions below. NOTE the entire response for this question should not exceed 1 typed page (11pt font). a. [10pts] Compare and contrast the attributes of a type-1 and type-2 macrophage. b. [5pts] What key markers of M1 and M2 were validated in the in vitro studies? c. [10pts] Summarize the key finding(s) of this study. 3. (25pts total) Researchers are interested in determining the host response to two different biomaterials: polypropylene and thermoplastic poly(carbonate) urethane (TPU). Two experiements were conducted: 1) investigation of total granuloma size at two time points (7 and 21 days) and 2) assessment of total macrophage count around the biomaterial. The biomaterials were implanted subcutaneously in rats. a. (5pts)Describe the results from Figure A. What significant differences are there? What do they mean? b. (5pts) Describe the results from Figure B. What significant differences are there? What do they mean? c. (2pts) For both Figure A and B, what statistical test was most likely conducted? d. (5pts) Based on Part A and B, which biomaterial would you recommend using and why? e. (8pts) What are two additional experiments that you would conduct to further investigate the host’s response to implantation? Include the independent variable, dependent variable, and added value (importance) of running the experiment. Figure B: Percentage of Positive Cells. Data presented are means with SEM. Significance stars indicate p<0.05. Figure A. Granuloma sizes in µm. Data presented are means with SEM. No significant differences were seen between any of the groups or time points.