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Synthesis and characterisation of biologically compatible TiO2 nanoparticles.

Cheyne RW, Smith TA, Trembleau L, McLaughlin AC - Nanoscale Res Lett (2011)

Bottom Line: We describe for the first time the synthesis of biocompatible TiO2 nanoparticles containing a functional NH2 group which are easily dispersible in water.The synthesis of water dispersible TiO2 nanoparticles coated with mercaptosuccinic acid is also reported.We show that it is possible to exchange the stearic acid from pre-synthesised fatty acid-coated anatase 5-nm nanoparticles with a range of organic ligands with no change in the size or morphology.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Chemistry Department, University of Aberdeen, AB24 3 UE, UK. a.c.mclaughlin@abdn.ac.uk.

ABSTRACT
We describe for the first time the synthesis of biocompatible TiO2 nanoparticles containing a functional NH2 group which are easily dispersible in water. The synthesis of water dispersible TiO2 nanoparticles coated with mercaptosuccinic acid is also reported. We show that it is possible to exchange the stearic acid from pre-synthesised fatty acid-coated anatase 5-nm nanoparticles with a range of organic ligands with no change in the size or morphology. With further organic functionalisation, these nanoparticles could be used for medical imaging or to carry cytotoxic radionuclides for radioimmunotherapy where ultrasmall nanoparticles will be essential for rapid renal clearance.

No MeSH data available.


Part of the 1H NMR spectrum (400 MHz) in D2O. For Asp-coated nanoparticles (A) and free aspartic acid-coated nanoparticles (B). Number sign, residual dioxane from Boc deprotection.
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Figure 4: Part of the 1H NMR spectrum (400 MHz) in D2O. For Asp-coated nanoparticles (A) and free aspartic acid-coated nanoparticles (B). Number sign, residual dioxane from Boc deprotection.

Mentions: The Asp nanoparticles were further investigated by NMR. The proton NMR spectrum of free aspartic acid (Figure 4) shows a doublet of doublets at 4.09 ppm (3J = 4.4 Hz; 3J = 6.8 Hz) and two doublets of doublets at 3.05 ppm (2J = 18 Hz; 3J = 4.4 Hz) and 2.98 ppm (2J = 18 Hz; 3J = 6.8 Hz). For the aspartic acid-coated nanoparticles, these signals are significantly shifted downfield (0.05 to 0.17 ppm) and they are slightly broadened. Curiously, the geminal coupling constant for the CH2 group has apparently disappeared as the CH group appears as a triplet (J = 5.6 Hz) and the CH2 group appears as a doublet (J = 5.2 Hz). Since the two methylene hydrogens are diastereotopic, the most likely explanation to this anomaly is that the chemical environment of both nuclei is such that they have almost identical chemical shifts. The discrepancy in the coupling constants (5.6 versus 5.2 Hz) can be explained by the signals given by the doublet and triplet appearing slightly broad. A two-dimensional (2D) correlation spectroscopy (COSY) experiment on these nanoparticles confirmed this coupling (Figure 5). The strong correlation clearly seen between the CH triplet (4.25 ppm) and the CH2 doublet (3.09 ppm) indicates that despite the unusual coupling constants obtained from the 1H NMR, the nuclei in question are spin coupled. This validates their identities and indicates that the nanoparticle contains aspartic acid as a ligand albeit in a slightly altered chemical state to that of the free acid.


Synthesis and characterisation of biologically compatible TiO2 nanoparticles.

Cheyne RW, Smith TA, Trembleau L, McLaughlin AC - Nanoscale Res Lett (2011)

Part of the 1H NMR spectrum (400 MHz) in D2O. For Asp-coated nanoparticles (A) and free aspartic acid-coated nanoparticles (B). Number sign, residual dioxane from Boc deprotection.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211840&req=5

Figure 4: Part of the 1H NMR spectrum (400 MHz) in D2O. For Asp-coated nanoparticles (A) and free aspartic acid-coated nanoparticles (B). Number sign, residual dioxane from Boc deprotection.
Mentions: The Asp nanoparticles were further investigated by NMR. The proton NMR spectrum of free aspartic acid (Figure 4) shows a doublet of doublets at 4.09 ppm (3J = 4.4 Hz; 3J = 6.8 Hz) and two doublets of doublets at 3.05 ppm (2J = 18 Hz; 3J = 4.4 Hz) and 2.98 ppm (2J = 18 Hz; 3J = 6.8 Hz). For the aspartic acid-coated nanoparticles, these signals are significantly shifted downfield (0.05 to 0.17 ppm) and they are slightly broadened. Curiously, the geminal coupling constant for the CH2 group has apparently disappeared as the CH group appears as a triplet (J = 5.6 Hz) and the CH2 group appears as a doublet (J = 5.2 Hz). Since the two methylene hydrogens are diastereotopic, the most likely explanation to this anomaly is that the chemical environment of both nuclei is such that they have almost identical chemical shifts. The discrepancy in the coupling constants (5.6 versus 5.2 Hz) can be explained by the signals given by the doublet and triplet appearing slightly broad. A two-dimensional (2D) correlation spectroscopy (COSY) experiment on these nanoparticles confirmed this coupling (Figure 5). The strong correlation clearly seen between the CH triplet (4.25 ppm) and the CH2 doublet (3.09 ppm) indicates that despite the unusual coupling constants obtained from the 1H NMR, the nuclei in question are spin coupled. This validates their identities and indicates that the nanoparticle contains aspartic acid as a ligand albeit in a slightly altered chemical state to that of the free acid.

Bottom Line: We describe for the first time the synthesis of biocompatible TiO2 nanoparticles containing a functional NH2 group which are easily dispersible in water.The synthesis of water dispersible TiO2 nanoparticles coated with mercaptosuccinic acid is also reported.We show that it is possible to exchange the stearic acid from pre-synthesised fatty acid-coated anatase 5-nm nanoparticles with a range of organic ligands with no change in the size or morphology.

View Article: PubMed Central - HTML - PubMed

Affiliation: The Chemistry Department, University of Aberdeen, AB24 3 UE, UK. a.c.mclaughlin@abdn.ac.uk.

ABSTRACT
We describe for the first time the synthesis of biocompatible TiO2 nanoparticles containing a functional NH2 group which are easily dispersible in water. The synthesis of water dispersible TiO2 nanoparticles coated with mercaptosuccinic acid is also reported. We show that it is possible to exchange the stearic acid from pre-synthesised fatty acid-coated anatase 5-nm nanoparticles with a range of organic ligands with no change in the size or morphology. With further organic functionalisation, these nanoparticles could be used for medical imaging or to carry cytotoxic radionuclides for radioimmunotherapy where ultrasmall nanoparticles will be essential for rapid renal clearance.

No MeSH data available.