Appendix A: Mesoporous Silica Particles in Biological Applications

Transcription

1 Appendix A: Mesoporous Silica Particles in Biological Applications Klimisch Criteria Figure 1. Klimisch criteria in the ToxRTool for the reliability assessment of in vivo toxicity studies.

2 118 The Klimisch criteria in chapter 1 come from a spreadsheet released by the European Commission, JRC, IHCP, In Vitro Methods Unit/ECVAM. The spreadsheet is used for determining the reliability of information in toxicological studies. Reliability is determined by scoring the study either a one or a zero depending on whether or not data is available for specific criteria. A blank scoring sheet for in vivo studies is given above. A separate set of criteria exists for in vitro studies. There is a maximum score of 1 and a minimum score of 4 possible for evaluations. Categories that are written in red are deemed absolutely necessary and if found to be missing will lower the score by a whole value for each missing item (e.g. from 1 to 2 for one missing red item). The scoring for reliability is as follows: 1 reliable without restrictions, 2 reliable with restrictions, 3 not reliable, 4 not assignable. Glossary of Biomarker Studies This chapter deals heavily with different ways that the toxicology of mesoporous silica particles is established. As such, some of the methods used for evaluating toxicity are not familiar to readers trained solely in chemistry. A brief glossary of some of the biomarker studies is included here for clarification. Caspase 3/7 Caspase enzymes cleave repair enzymes and disassemble the structure of dying cells. These enzymes are activated downstream of the apoptosis initiation cascade and so measure the amount of cells that are currently undergoing or have recently undergone apoptosis. Caspase assays use the active enzyme to cleave an ester bond on reporter molecule (Scheme 1), the reporter is then fluorescently active and the amount of fluorescence then corresponds to the activity of caspases in the study of interest. The higher the reported fluorescence, the higher the caspase levels, the more toxic are the conditions being tested. Scheme 1. Cleavage of the ester bond in a rhodamine dye analog by caspase 3/7 to produce the fluorescently active product.

3 119 MTT assay The MTT is one of the most widely used assays to for determining cell viability. These assays work when a mitochondrial reductase enzyme cleaves a nitrogen-nitrogen bond in a tetrazole (sceme 2). This results in a colored product which can be read on a typical plate reader instrument or UV-Vis spectrometer. The higher the value for the MTT assay (the more absorbance), the healthier the population of cells. Scheme 2. Cleavage of the nitrogen-nitrogen bond to produce the highly colored (purple) product. Annexin V In many cell types, the transposition of diglycerides with phosphatidylserine headgroups from the inner bilayer to the outer bilayer is an early indicator of apoptosis. The protein Annexin V has a strong, specific affinity for phosphatidylserine and is labeled with a fluorescent reporter, typically fluorescein. The cells are exposed to Annexin V and the portion of the cell population undergoing apoptosis is then fluorescently labeled due to the protein-headgroup binding. ALT (alanine transferase), AST (aspartate transferase) Alanine and aspartate transferases are proteins that are normally confined to the liver. However, when the liver is damaged from cirrhosis, jaundice, or exposure to toxic compounds, the concentrations of ALT and AST in the blood are found to increase.

4 Appendix B: Lipid Bilayer Coated Silica The data included in Appendix B are a collection of additional measurements used in determing the cytotoxicity of the small-pore lipid-bilayer mesoporous silica nanoparticles (LB-MSN). Included are the complete sets of data for each of the studied phospholipids and materials characterization data used to design the control conditions for cell growth assays. Synthesis of (+) Control MSN: MSN particles are grafted with 3-mercaptoproyltriethoxy silane as previously described (MP-MSN). 100 mg of MP-MSN are suspended in 250 ml of methanol and 1 mmol of 2,2 dithiodipyridyl added and the mixture is allowed to react overnight at room temperature. The resulting material is collected via centrifugation and is then resuspended in 250 ml of 200 μm fluorescein in methanol and 1 mmol of 1-thiol-2,3-dipalmitoylpropane is added to the mixture and allowed to stir overnight before being collected via centrifuge and dried in vacuo overnight. Figure 1. Thermal Gravimetric Analysis (TGA) data for DP-MSN and LB-MSN. Dipalmitoylphosphatidyl choline loss is found between 240 and 305 o C and accounts for 20% of the mass of the LB-MSN.

5 121 Figure 2. Cytotoxicity of MSN in HeLa Cells Figure 3. Cytotoxicity of HeLa cells incubated with DPPC only for 24 hours.

6 122 Figure 4. Cytotoxicity of NLC incubated with DPPC only for 24 hours Figure 5. Cytotoxicity of LB-MSN coated with DPPC in HeLa cells

7 123 Figure 6. Cytotoxicity of LB-MSN coated with DPPC in NLC cells Figure 7. Cytotoxicity of LB-MSN coated with dipalmitoylphosphatidylethanolamine in HeLa cells

8 124 Figure 8. Cytotoxicity of LB-MSN coated with dipalmitoylphosphatidylethanolamine in NLC cells Figure 9. Cytotoxicity of LB-MSN coated with dipalmitoylphosphatidic acid in HeLa cells

9 125 Figure 10. Cytotoxicity of LB-MSN coated with dipalmitoylphosphatidic acid in NLC cells Figure 11. Cytotoxicity of LB-MSN coated with cardiolipin in HeLa cells

10 126 Figure 12. Cytotoxicity of LB-MSN coated with cardiolipin in NLC cells Figure 13. Release of fluorescein from LB-MSN using glutathione as the disulfide cleaving agent. Glutathione is added at the 240 minute data point.

11 Appendix C: Synthesis of New Materials using the Hydrolysis and Condensation of Alkoxysilane Precursors

12 127 Table 1. Synthesis conditions and molar ratios of reactants for all materials derived from the water in oil emulsion. Table 1 continued. Synthesis conditions and molar ratios of reactants for all materials derived from the water in oil emulsion.

13 128 5RR-78-1 Figure 1. TEM of 5RR-78-1, the left image is a 52 kx magnification of the boxed area in the right image. Figure 2. Clockwise from top left are SEM images (15 kx) for 5RR-78-2, 5RR-78-3 and 5RR-78-4

14 129 Figure 3. Clockwise from top left are SEM images (15 kx) for materials 5RR-79-1, 5RR-79-2, and 5RR Figure 4. Images of materials synthesized at 30 o C (5RR-80-1), the red box indicates the area examined under higher magnification (69 kx).

15 130 Figure 5. Scanning electron microscope images of materials 5RR-81-1 (left) and 5RR-81-3, synthesized for 2 and 6 hours respectively (50 kx).

16 Figure 6. X-ray diffraction patterns for materials synthesized in 2 : 1 and 4 : 1 oil to water (84-1 and 84-4 respectively). A slight degradation of higher ordering is observed when the oil to water ratio is shifted from 3:0. The y-axis values are offset for clarity, the x-axis is measured in degrees 2*Theta. Figure 7. Scanning electron microscope images of materials 5RR-84-1 and 5RR Altering the oil to water ratio changes the polydispersity of the particle diameters more than it alters the pore structure.

17 Figure 8. X-ray diffraction patter for materials prepared in solutions with varying hexane: water ratios. Patterns for synthesis ratios of 2:1, 3:1, and 4:1 (85-1, 85-2 and 85-3 respectively) are shown. Using hexanes as the continuous phase represents a significant cost reduction over the standard decane: water system.

18 Figure 9. X-ray diffraction patter for materials prepared in solutions with varying hexanedecane: water ratios. Patterns for synthesis ratios of 2:1, 3:1, and 4:1 (86-1, 86-2 and 86-3 respectively) are shown. The use of hexadecane results in amorphous particles presumable due to intercalation of the continuous pahse with the structure directing agent, CTAB Figure 10. X-ray diffraction patter for materials prepared in 1:1 and 5:1 hexane: water (87-1 and 87-2 respectively).

19 Figure 11. X-ray diffraction patter for materials prepared with mechanical stirring at 500 rpm Figure 12. X-ray diffraction patter for materials prepared in 3:1 decane:water systems with variations in Si:CTAB molar ratio. The molar ratios for Si:CTAB are 1:0.05, 1:0.127, and 1:0.382 for experiments 93-2, 93-3, and 93-4 respectively.

20 All signal data is multiplied 5x to show peaks Figure 13. X-ray diffraction patter for materials prepared in 3:1 decane:water systems with variations in Si:CTAB molar ratio. The molar ratios for Si:CTAB are 1:3.19, 1:6.38, and 1:12.8 for experiments 93-5, 93-6, and 93-7 respectively.

21 136 Figure 1. Clockwise from upper left are samples 5RR-93-3, 5RR-93-4, 5RR-93-5, 5RR-93-7 and 5RR These materials were synthesized using an increasing concentration of CTAB (3 7). The morphology slowly changes from particles to a foam-like structure. All images are taken at 15 kx.

22 137 Table 2. The results of the optimization of the PMO structure. Relevant adjustments to synthesis parameters are noted in columns 2 and 3. Column 4 (Result) gives a qualitative assignment to the X- ray diffraction and transmission electron microscope images. The results are as follows; a (-) indicates lack of the preceding characteristic. A (+) indicates ordered structures while (++) indicates very well ordered systems. The lack of a qualifier (-) or (+) indicates that ordering was observed but weak. The abbreviation meso means mesoporous.

23 Appendix D: The structure of ligands presented in the tables of Chapter 4 Figure 1. Ligands listed in Table 1. The structures presented refer to specific entries: ligand A.- entry 1, B. - entry 2, C. - entry 3, D. entries 4, 5, 6, 8, and 9, E. entry 7.

24 139 Figure 2. Ligands listed in table 2. The structures presented refer to specific entries; Ligand A. entries 1 and 2, B. entry 3, C. entries 4-11, D. entry 12, E entry 13.

25 140 Figure 3. Ligands listed in table 3. The structures presented refer to specific entries; Ligand A. entry 1, B. entry 7, C. entry 8, D. entry 9, E. entry 10.

26 Spectroscopic Envidence 1,3-methylpyridineimidazole bromide (2): 141