Integration Of Biomaterials And Nanotechnology Biology Essay

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Introduction

Combining Technologies

The integration of biomaterials and nanotechnology enables scientist the opportunity to develop new materials that are in nanometre scale. Such materials have the potential to be used in biological science and clinical medicine. [1] Biomaterials such as dendrimers are being extensively researched as they have physicochemical properties that resemble that of biomaterials, namely proteins. [2]

Dendrimers

Dendritic structures are structures that are used extensively in nature when a particular function needs to be exposed or enhanced. For instance in the case of trees, above ground, the branching structure adopts a dendritic motif to maximise the exposure of its leaves to sunlight, allowing the tree live and grow through photosynthesis. Underground, the tree also uses a similar system to maximise the amount of water it can uptake (Figure 1). [3] The usefulness of a dendritic structure can also be found in the foot pad of the gecko. It was found that the gecko is able to stay on a glass surface through dry adhesion due to the presence of a dendritic network of foot hairs (Figure 2). This architecture creates an extraordinarily strong adhesion through van der Waals forces that exists between each foot hair and the surface. [4] Dendrimers are a class of synthetic organic chemistry that adapted the branching dendritic structure to form a cascading highly branched, multivalent, globular macro-molecules structure. This class of molecules also has the advantage of having a unique well-defined molecular weight or low-polydispersity index. [2, 5, 6]

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Figure : Adapted from Dendrimers: design, synthesis and chemical properties. [3]

C:\Users\Amanda\Downloads\285726.jpg

Figure : Foot hairs on the Foot Pad of Gecko - Dennis Kunkel Microscopy, Inc./Visuals Unlimited, Inc.

Nanoparticles

There is extensive research into the field of nanotechnology as it is found that when a material is reduced to nanoscale, various properties of the materials such as optical, thermal, magnetic and even toxicity changes. This is due to increased surface reactivity because of the large percentage of atoms that are now at the surface and quantum effects. and the which is the has become , are comparable with biological structures that are also in the same size range. ere found to exhibit different properties from the bulk properties when at reduced to the nanoscale. This is due to the quantum effects and the increased relative surface area (the surface area to volume ratio approaches 1)

The scope of this paper will cover the development of a dendron (a single unit of molecule or motif) that will be used as a 'linker' rather than to form a cascading molecule. The purpose of such a molecule will be to form a bond with a Zinc Oxide Nanoparticle, ZnO (np).

ZnO is the target binding nanoparticle as it has been found to have selective toxicity

Results & Discussion

What did we get? sucessful/ unsucessful

In order to create the molecule that was designed in the previous chapter, the following steps were taken as shown in Scheme 1(figure ?). In Scheme 1, Undec-10-yn-ol (1 g, 5.95 mmol) and 4-iodoanisole were reacted overnight at 85 °C under N2 gas to yield a yellow oil. The reaction follows the Sonogashira Coupling mechanism. Though the actual mechanism is still unknown, the reaction can be explained by the latest proposed mechanism as shown below. The

Figure

Figure

Experimental Section

11-4(-Methoxyphenyl)undec-10-yn-1-ol)

Figure

To a degassed solution of dry Et3N (15 ml), THF (15 ml) and 4-iodoanisole (1.67 g, 7.14 mmol); [Pd(PPh3)4] (0.07 g, 0.6 mmol) and CuI (23 mg, 0.12 mmol) were added and the mixture was degassed a second time. Undec-10-yn-ol (1 g, 5.95 mmol) was then added and the reaction mixture was degassed one last time. The reaction mixture was stirred overnight at 85 °C under N2 gas.

After 24h, a precipitate formed and the mixture was filtered through celite and the solvent was concentrated under vacuum, extracted with EtOAc and purified by several precipitations from CH2Cl2 upon addition of MeOH to yield a yellow oil. The yield was 86%.

1H-NMR (400MHz, CDCI3) δ=7.30 (d, 2H, J = 8Hz, Ar-H), 6.78 (d, 2H, J = 8Hz, Ar-H), 3.76 (s, 3H, Ar-O-CH3), 3.60 (t, 2H, C-OH), 2.35 (t, 2H, CΞC-?) (

(1) (mass) and 3,4-bis(4'-methoxy-[1,1'-biphenyl]-4-yl)-2,5-diphenylcyclopenta-2,4-dienone (mass) were added together and o-Xylene was added. The solution mixture was then heated to 145 °C for 7 days. The mixture was separated by column

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Solvent 1:

To a degassed solution of dry Et3N (15 ml), THF (15ml), 4-iodoanisole (1.54 g, 6.6 mmol), [Pd(PPh3)4] (0.063 g, 0.55 mmol), and CuI (0.021 g, 0.11 mmol) were added and the mixture degassed a second time. 10-Undecnoic acid (1 g, 5.49 mmol) was then added, and the reaction mixture was degassed one last time and stirred overnight at 85 °C under N2 (g).

After 24h, the solvent was concentrated to remove the solvents and extracted with HCl (0.1 M) and CHCl3 (40 ml) 3 times. The organic layer was extracted MgSO4 was used to remove the water then it was filtered and dried.

Solvent 2:

To a degassed solution of dry Et3N (15 ml), DMF (15ml), 4-iodoanisole (1.54 g, 6.6 mmol), [Pd(PPh3)4] (0.063 g, 0.55 mmol), and CuI (0.021 g, 0.11 mmol) were added and the mixture degassed a second time. 10-Undecnoic acid (1 g, 5.49 mmol) was then added, and the reaction mixture was degassed one last time and stirred overnight at 85 °C under N2 (g).

After 24h, the solvent was concentrated to remove the solvents and extracted with HCl (0.1 M) and CHCl3 (40 ml) 3 times. The organic layer was extracted MgSO4 was used to remove the water then it was filtered and dried.

Solvent 3:

To a degassed solution of dry Et3N (30 ml), 4-iodoanisole (1.54 g, 6.6 mmol), [Pd(PPh3)4] (0.063 g, 0.55 mmol), and CuI (0.021 g, 0.11 mmol) were added and the mixture degassed a second time. 10-Undecnoic acid (1 g, 5.49 mmol) was then added, and the reaction mixture was degassed one last time and stirred overnight at 85 °C under N2 (g).

After 24h, the solvent was concentrated to remove the solvents and extracted with HCl (0.1 M) and CHCl3 (40 ml) 3 times. The organic layer was extracted MgSO4 was used to remove the water then it was filtered and dried.

NaOH (0.69 g, 17.13 mmol) was added to a solution of Triethylene Glycol (21.95 g, 113 mmol) in THF (5 ml) at 0 °C, followed by a slow addition of a solution of p-toluenesulfonylchloride (2.08 g, 10.93 mmol) in THF (20 ml). The reaction mixture was then stirred for 2 h at 0 °C and poured into a mixtrure if ice and water. The organic layer was separated, and the aqueous layer was extracted with CH2Cl2. The combined organic layers were washed with water, dried over MgSO4 and evaporated in vacuo to yield as a yellow oil.

2-[2-(2-{2-[2-(2-Methoxy-ethoxy)-ethoxy]-ethoxy}-ethoxy)-ethoxy]-ethanol (ii)

To a solution of 2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethyl 4-methylbenzenesulfonate (i) (0.50 g, 0.00144 mmol) in dry dichloromethane (10 mL), silver oxide (0.40 g, 0.0172 mmol) was added portionwise for 1h at room temperature while stirring. Methyl iodide (0.55 g, 0.00287 mmol) was then added drop wise at 0 °C. Stirring was continued for 24 h. The reaction mixture was filtered through celite, washed with dichloromethane (3 x 10 mL). Removal of the solvent and flash column chromatography of the residual mass using dichloromethane/methanol (95:5) afforded the product ii (2.9 g, 50%) as yellow oil.

(R8) was prepared by a modification of a method reported previously. 3,4-bis(4'-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)biphenyl-4-yl)-2,5-diphenylcyclopenta-2,4-dienone (Amos 25) (______ g, _____ mmol) and 12-(4-methoxyphenyl)dodec-11-ynoic acid (R5) (____ g, ____ mmol) were combined in diphenyl ether ( 5 g ) and heated overnight at ref lux under N2. The solution was then cooled to 25 oC and diluted with ethanol. The resulting precipitate was separated by f iltration and washed with ethanol to give (R8) (6; 8.45 g, 17.9 mmol, 89%) as a colorless powder. 1H NMR spectroscopic data matched those reported earlier. 1HNMR(400 MHz, CDCl3) Æ’Â 1.92 (s, 3H), 6.80-6.85 (m, 15H), 7.09-7.18 (m, 10H); 13C NMR(100 MHz, CDCl3) Æ’Â 19.8, 125.2, 125.3, 126.1, 126.6, 126.6, 127.6, 130.5, 131.3, 131.5, 133.6, 138.7, 140.3, 140.7, 140.8, 141.1, 141.4; HRMS (ESI-TOF) calcd for C37H28 t H m/z 473.22638, found 473.22569; calcd for C37H28 t Na m/z 495.20832, found 495.20789.

1. Hanley, C., et al., Preferential killing of cancer cells and activated human T cells using ZnO nanoparticles. Nanotechnology, 2008. 19(29).

2. Boas, U. and P.M.H. Heegaard, Dendrimers in drug research. Chemical Society Reviews, 2004. 33(1): p. 43-63.

3. Boas, U., J.B. Christensen, and P.M.H. Heegaard, Dendrimers: design, synthesis and chemical properties. Journal of Materials Chemistry, 2006. 16(38): p. 3786-3798.

4. Autumn, K., et al., Adhesive force of a single gecko foot-hair. Nature, 2000. 405(6787): p. 681-685.

5. Gajbhiye, V., et al., Pharmaceutical and biomedical potential of PEGylated dendrimers. Current Pharmaceutical Design, 2007. 13(4): p. 415-429.

6. Gillies, E.R. and J.M.J. Frechet, Dendrimers and dendritic polymers in drug delivery. Drug Discovery Today, 2005. 10(1): p. 35-43.

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