Analytical Research Seminar NANOPARTICLES DERIVED FROM A GROUP OF UNIFORM MATERIALS BASED ON ORGANIC SALTS Analytical Research Seminar Aaron Tesfai Warner Research Group Department of Chemistry. Louisiana State University. Baton Rouge,LA 70803

Outline Introduction to Ionic Liquids (ILs) Brief history Common cation/anion combinations Properties of ILs Group of Uniform Materials Based on Organic Salts (GUMBOS) Synthesis and Characterization of Micro- and NanoGUMBOS Surfactantless Melt-Emulsion-Quench Surfactant-Assisted-Melt-Emulsion-Quench Reverse Micelle Magnetic Particles from GUMBOS Synthesis and characterization of [Bm2Im][FeCl4] GUMBOS particles Magnetic susceptibility of [Bm2Im][FeCl4] GUMBOS particles

Ionic Liquids (ILs) Ionic liquids are defined as organic salts with melting points at or below 100 °C Liquid at room temperature (room temperature ionic liquids RTILs) Solid above room temperature (frozen ionic liquids) The name ILs was first used by a Latvian-German chemist Paul Walden Walden discovered the first ionic liquid, ethyl ammonium nitrate with a melting point of 12 °C in 1914 The term ILs used to distinguish these compounds from inorganic salts that melt at high temperature Low melting point - asymmetry between the ions prevent formation of stable crystal lattice (“frustrated crystal packing”) www.uni-tuebingen.de Welton T. Chem Rev 1999, 99, 2071-2083 Philippe Hapiot and Corinne Lagrost Chem. Rev. 2008, 108, 2238–2264 Del Po’polo, M. G.; Voth, G. A. J. Phys. Chem. B 2004, 108, 1744-1752 P. Walden, Bull. Acad. Imper. Sci. (St. Petersburg) 1800 (1914)

Common Cations and Anions 1-alkyl pyridinium 1-alkyl-3-methyl-imidazolium Tetraalkyl-phosphonium Tetraalkyl-ammonium R = Ethyl, Butyl, Hexyl, Octyl and Decyl Common alkyl (R-) chains: Common anions: bis(trifluoromethylsulfonyl)imide hexafluorophosphate tetrafluoroborate nitrate

Properties of Ionic Liquids Tunability Thermal stability Dissolve many organic and inorganic materials Low volatility Environmentally friendly

Group of Uniform Materials Based on Organic Salts (GUMBOS) 1-butyl-2,3-dimethylimidazolium tetrachloroferrate M.P. -2 °C 1,3,3-Trimethyl-2-[7-(1,3,3-trimethyl-1,3-dihydro-indol-2-ylidene)-hepta-1,3,5-trienyl]-3H-indolium bis(trifluoromethylsulfonyl)imide M.P. > 120 °C Tesfai et al. ACS Nano. 2009 accepted. Bwambok et al. submitted to ACS Nano 2009.

Objectives To investigate the use of GUMBOS that are solid above room temperature for possible GUMBOS-based nano- and micro- particle synthesis To characterize the nano- and microGUMBOS Scanning Electron Microscopy (SEM) Transmission Electron Microscopy (TEM) Differential Interference Contrast (DIC) Fluorescence Microscopy Atomic Force Microscopy To dope the GUMBOS and investigate the possibility of using nanoGUMBOS to entrap various materials such as drug molecules

Synthesis and Characterization of Micro- and NanoGUMBOS Surfactantless Melt-Emulsion-Quench Surfactant-Assisted Melt-Emulsion-Quench Reverse Micelle

GUMBOS Used [bm2Im][PF6] [1-butyl-2,3-dimethylimidazolium] [hexafluorophosphate] GUMBOS Melting point Miscibility with H2O [1-butyl-2,3-dimethylimidazolium] [hexafluorophosphate] 42 °C No

Surfactantless Synthesis of NanoGUMBOS 1. Add 25 mg of GUMBOS into 8 mL of DI water 2. Heat mixture at 70 °C 3. Homogenize solution for 10 min, Probe sonication for 10 min 4. Freeze mixture in an ice water bath 1 2 4 3 Tesfai et al. Nano Lett. 2008, 8, 897-901.

Characterization of NanoGUMBOS SEM TEM Electron micrographs of [bm2Im][PF6] nanoGUMBOS synthesized using surfactantless synthesis: (a) SEM image showing an average nanoparticle diameter of 90 ± 32 nm. (b) TEM image with an average nanoparticle diameter measured as 88 ± 34 nm. Tesfai et al. Nano Lett. 2008, 8, 897-901.

Surfactantless Synthesis: Nile Red Doped NanoGUMBOS (A) solid [Bm2Im][PF6] (B) melted [Bm2Im][PF6] (C) o/w emulsion (D) [Bm2Im][PF6] nanoparticle crop Tesfai et al. Nano Lett. 2008, 8, 897-901.

Surfactantless Synthesis : SEM and Optical Microscopy (DIC) and (Fluorescence) of microGUMBOS Solid [bm2Im][PF6] microGUMBOS with average diameters of ~ 3-μm imaged with (a) SEM, (b) Optical microscopy (DIC), (c) Optical microscopy (fluorescence), (d) Overlay of DIC and fluorescence. Tesfai et al. Nano Lett. 2008, 8, 897-901.

Synthesis and Characterization of Micro- and NanoGUMBOS Surfactantless-Melt-Emulsion-Quench Surfactant Assisted-Melt-Emulsion-Quench Reverse Micelle

Surfactant-Assisted Synthesis of NanoGUMBOS 1. Add 1% w/v Brij-35 in DI water 2. Add 25 mg of GUMBOS to mixture and placed in water bath set to 70 °C 3. Homogenize solution for 10 min, Probe Sonication for 10 min 4. Freeze mixture in an ice water bath 1 3 2 4 Tesfai et al. Nano Lett. 2008, 8, 897-901.

Surfactant-Assisted Synthesis: TEM of NanoGUMBOS Representative TEM image of 45 ± 7 nm [bm2Im][PF6] nanoGUMBOS synthesized using surfactant-assisted synthesis, employing Brij-35. Tesfai et al. Nano Lett. 2008, 8, 897-901.

Synthesis and Characterization of Micro- and NanoGUMBOS Surfactantless-Melt-Emulsion-Quench Surfactant Assisted-Melt-Emulsion-Quench Reverse Micelle

Surfactant Employed for Reverse Micelle Synthesis: Aerosol-OT (AOT) Sodium bis(2-ethyl-hexyl)sulfosuccinate (AOT) Double chain amphiphile Able to form reverse micelles Able to solubilize water R value (wo): [water]/[surfactant] AOT Reverse Micelle Bulk Heptane Continuum Inner Bulk Water AOT Interface Bound Water

Basic Processes for Nanoparticle Formation within AOT Reverse Micelles 0.1 M AOT in 5 mL heptane 120 μL of 0.2-0.6 M [Bm2Im][Cl] in water A [Na][BF4] B Tesfai et al. ACS Nano. 2009. accepted

TEM Images of [Bm2Im][BF4] NanoGUMBOS Reagent Concentration (M) Particle Size (nm) Standard Deviation (nm) A: 0.2 14.7 ± 2.2 B: 0.4 20.8 ± 1.8 C: 0.5 34.3 ± 4.8 D: 0.6 68.0 ± 17 Tesfai et al. ACS Nano. 2009. accepted

Size Distributions of [Bm2Im][BF4] NanoGUMBOS Synthesized in water-containing AOT reverse micelles at various reagent concentrations: [AOT] = 0.1 M; molar reagent concentrations: 0.2, 0.4, 0.5, and 0.6 M. Tesfai et al. ACS Nano. 2009 accepted.

Tapping Mode AFM Images of [Bm2Im][BF4] NanoGUMBOS 220 nm 220 nm B B 0.4 M [Bm2Im][BF4] 12 µ m 12 µ m C C 200 nm 200 nm D D 2 µ m 2 µ m (A) 60 × 60 μm2 topographical image and (B) simultaneously acquired phase image. (C) Zoom-in view 12 × 12 μm2 view and (D) corresponding phase channel. Tesfai et al. submitted to ACS Nano. 2009. Tesfai et al. ACS Nano. 2009 accepted.

Conclusions NanoGUMBOS (SEM) were obtained with average diameters of 90 nm using Surfactantless-Melt-Emulsion-Quench-Technique. TEM was in good agreement with SEM yielding average diameters of 88 nm (Surfactantless-Melt-Emulsion-Quench-Technique). MicroGUMBOS (SEM) were obtained with average diameters of ~3 μm (Surfactantless-Melt-Emulsion-Quench-Technique). Doping the microGUMBOS suggests that they may be used to entrap various materials including drugs. The use of an emulsifying agent (Surfactant-Assisted-Melt-Emulsion-Quench-Technique)yields nanoGUMBOS of ~45 nm in diameter. Smaller particle size Size control A facile and reproducible method for synthesizing four distinct sizes of nanoGUMBOS has been developed (Reverse Micelle Synthesis). NanoGUMBOS size was influenced by increasing reagent concentration within each reverse micelle.

Magnetic Particles From GUMBOS

Applications of Magnetic Nanoparticles Magnetothermal Iron oxide magnetic nanoparticles injected In tumor Application of external magnetic field Drug Targeting Superparamagnetic iron oxide nanoparticles are guided towards the lungs in the presence of an external magnetic field Amirfazli, A. Nature Nanotech. 2007, 8, 467-468.  

Objectives To investigate the use of magnetic GUMBOS for possible GUMBOS-based particle synthesis To characterize the GUMBOS particles Transmission Electron Microscopy (TEM) Atomic Force Microscopy

Magnetic Particles from GUMBOS Synthesis and characterization of [Bm2Im][FeCl4] GUMBOS particles Magnetic susceptibility of [Bm2Im][FeCl4] GUMBOS particles

Basic Processes for Magnetic Particle Formation within AOT Reverse Micelles. 0.1 M AOT in 5 mL heptane 120 μL of 0.3 - 0.4 M [FeCl3].6H2O in water B 0.1 M AOT in 5 mL heptane 120 μL of 0.3 - 0.4 M [Bm2Im][Cl] in water A Tesfai et al. ACS Nano. 2009 accepted.

TEM Images of Magnetic GUMBOS Particles Micrographs of magnetic [Bm2Im][FeCl4] GUMBOS particles obtained from TEM revealing mean particle sizes of (A) 98.0 ± 17 nm and (B) 199.0 ± 26 nm. Reagent Concentration (M) Particle Size (nm) Standard Deviation (nm) A: 0.3 98 ± 17 B: 0.4 199 ± 26 Tesfai et al. ACS Nano. 2009 accepted.

Size Distributions of Magnetic GUMBOS Particles [AOT] = 0.1 M; molar reagent concentrations: 0.3 and 0.4 M. Tesfai et al. ACS Nano. 2009 accepted.

Tapping Mode AFM Images of [Bm2Im][FeCl4] GUMBOS Particles 0.3 M [Bm2Im][FeCl4] 0.4 M [Bm2Im][FeCl4] (A) Topographical image of magnetic nanoGUMBOS with a diameter near 100 nm and (B) the matching phase image. (C) Topography of 200-nm GUMBOS Particles and (D) the corresponding phase frame. Tesfai et al. ACS Nano. 2009 accepted.

Absorption Spectra of Bulk [Bm2Im][FeCl4] Tesfai et al. ACS Nano. 2009 accepted. 1Hayashi, S. et al. Chem. Lett. 2004, 33, 1590-1591.

Magnetic Susceptibility of Bulk [Bm2Im][FeCl4] Alongside [Bm2Im][FeCl4] NanoGUMBOS Magnetic Response (emu/g) [BmIm][FeCl4] 1 40.6x10-6 [HmIm][FeCl4] 1 39.6 x 10-6 [OmIm][FeCl4] 1 36.6 x 10-6 GUMBOS/nanoGUMBOS Magnetic Response (emu/g) [Bm2Im][FeCl4] GUMBOS 34.3 x 10-6 [Bm2Im][FeCl4] nanoGUMBOS 1Hayashi, S.; Hamaguchi, H.-o. Chemistry Letters. 2004, 33, 1590. Tesfai et al. ACS Nano. 2009 accepted.

Conclusions Two distinct sizes of magnetic nanoGUMBOS were synthesized and characterized Particle size was influenced by increasing reagent concentration in each reverse micelle. UV-Vis spectrum confirmed the well known characteristic peaks of FeCl4 for the bulk magnetic GUMBOS. Both the bulk and nanoGUMBOS demonstrated to be magnetic

Acknowledgements Prof. Isiah M. Warner Postdoctoral Research Associates Warner Research Group Garno Research Group National Science Foundation (NSF) National Institutes of Health (NIH) Phillip W. West Endowment 35