US009 127295B2 (12) United States Patent (10) Patent No.: US 9,127,295 B2 Rondinone et al. (45) Date of Patent: Sep. 8, 2015 Vasconcelos, et al., 1998. Copper(II) Complexation Properties and (54) MICROBIAL-MEDIATED METHOD FOR Surfactant Activity of 3-N,N-Bis(2-hydroxyethyl)amino-2- METAL OXDENANOPARTICLE hydroxypropanesulfonic Acid and N-(2-Hydroxyethyl)piperazine FORMATION N9-2-hydroxypropanesulfonic Acid pH Buffers Which May Affect Trace Metal Speciation in in Vitro Studies. Analytical Biochemistry (75) Inventors: Adam J. Rondinone, Knoxville, TN 265, 193-201.* (US); Ji Won Moon, Oak Ridge, TN Limbach et al. Environ. Sci. Technol. 2008, 42,5828-5833.* Love L.J., et al. “Characterization of Bio-Synthesized Magnetic (US); Lonnie J. Love, Knoxville, TN Nanoparticles'. Proceedings of the 2005 IEEE/ASME International (US); Lucas W. Yeary, Painted Post, NY Conference on Advanced Intelligent Mechatronics, Monterey, Cali (US); Tommy J. Phelps, Knoxville, TN fornia (Jul 24-28, 2005). 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Nov., Novel Antarctic Species With the Ability to Produce Eicosapentaenoic Acid (20:50co3) and Grow (22) Filed: Jan. 22, 2009 Anaerobically by Dissimilatory Fe(III) Reduction'. International Journal of Systematic Bacteriology 47(4):1040-1047 (1997). (65) Prior Publication Data Lovley D.R. et al., “Geobacter metallireducens Gen. Nov. Sp. Nov., US 2010/O184179 A1 Jul. 22, 2010 a Microorganism Capable of Coupling the Complete Oxidation of Organic Compounds to the Reduction of Iron and Other Metals'. (51) Int. Cl. Arch. Microbiol. 159:336-344 (1993). CI2P3/00 (2006.01) Official Action dated Aug. 29, 2013 in U.S. Appl. No. 12/364,638. B825/00 (2011.01) * cited by examiner B824.0/00 (2011.01) (52) U.S. Cl. Primary Examiner — Janet Epps-Smith CPC. CI2P3/00 (2013.01); B82Y5/00 (2013.01); (74) Attorney, Agent, or Firm — Scully, Scott, Murphy & B82Y40/00 (2013.01) Presser, P.C. (58) Field of Classification Search CPC .............. B82Y 40/00; B82Y5/00; C12P3/00 (57) ABSTRACT USPC .......................................................... 435/168 The invention is directed to a method for producing metal See application file for complete search history. oxide nanoparticles, the method comprising: (i) Subjecting a combination of reaction components to conditions conducive (56) References Cited to microbial-mediated formation of metal oxide nanopar U.S. PATENT DOCUMENTS ticles, wherein said combination of reaction components comprise: metal-reducing microbes, a culture medium Suit 4,954.231 A * 9/1990 Correia et al. ............. 204,157.6 able for Sustaining said metal-reducing microbes, an effective 6,444,453 B1 9, 2002 Laufetal. 7,060,473 B2 6/2006 Phelps et al. concentration of one or more Surfactants, a reducible metal 2002fO187889 A1 12, 2002 Laufetal. oxide component containing one or more reducible metal 2006, OO14261 A1 1/2006 Phelps et al. species, and one or more electron donors that provide dona 2008/O108749 A1 5/2008 Chen ............................. 524/795 table electrons to said metal-reducing microbes during con 2010.0193752 A1 8/2010 Phelps et al. Sumption of the electron donor by said metal-reducing 2010/0330367 A1 12/2010 Phelps et al. microbes; and (ii) isolating said metal oxide nanoparticles, OTHER PUBLICATIONS which contain a reduced form of said reducible metal oxide component. The invention is also directed to metal oxide Moon, et al., 2007. Microbial preparation of metal-substituted mag nanoparticle compositions produced by the inventive method. netite nanoparticles. Journal of Microbiological Methods 70: 150 158.* 21 Claims, 5 Drawing Sheets U.S. Patent Sep. 8, 2015 Sheet 1 of 5 US 9,127,295 B2 Provide Source of Reducible Metal Provide an Effective Amount of Surfactant Establish Bacterial Culture Suitable for Reducing Metal Reduce Metal to Form Doped Particulate F.G. 1 U.S. Patent Sep. 8, 2015 Sheet 2 of 5 US 9,127,295 B2 40 20 Y = -1.4796Ln(X) + 30.64 R2 = 0.203 1 10 100 1000 Concentration (mg/L) Drift AA Snow Max MeOH PFT Fe ACAC Decanoic acid Benzoic acid Trifluoracetic acid r ar. aar a a r r a Control FIG. 2 U.S. Patent Sep. 8, 2015 Sheet 3 of 5 US 9,127,295 B2 GN Q 42 2 5aria K S. 40 38 S O S) 36 S 34 0 200 400 600 800 1000 Surfactant concentration (ppm) FIG. 3 U.S. Patent Sep. 8, 2015 Sheet 4 of 5 US 9,127,295 B2 38 30 32 34 40 B e o soada uses 2 s ::::::::::: -- ... .a ... we FIG. 4 U.S. Patent Sep. 8, 2015 Sheet 5 of 5 US 9,127,295 B2 FIG. 5 US 9, 127,295 B2 1. 2 MICROBAL-MEDIATED METHOD FOR Surfactant also advantageously permits the particle size and/ METAL OXDENANOPARTICLE or morphology of the nanoparticles to be controlled. FORMATION In a preferred embodiment, the method involves: (i) sub jecting a combination of reaction components to conditions This invention was made with government Support under 5 conducive to microbial-mediated formation of metal oxide Contract Number DE-AC05-00OR22725 between the United nanoparticles, wherein said combination of reaction compo States Department of Energy and UT-Battelle, LLC. The nents include: metal-reducing microbes, a culture medium United States government has certain rights in this invention. Suitable for Sustaining said metal-reducing microbes, an effective concentration of one or more surfactants, a reducible FIELD OF THE INVENTION 10 metal oxide component containing one or more reducible metal species, and one or more electron donors that provide The present invention relates to the field of microbial syn donatable electrons to the metal-reducing microbes during thesis of inorganic materials, and more particularly, wherein consumption of the electron donor by the metal-reducing the inorganic materials are metal oxide nanoparticles. microbes; and (ii) isolating said metal oxide nanoparticles, 15 which contain a reduced form of said reducible metal oxide BACKGROUND OF THE INVENTION component. Thus, as will be described in further detail below, the Nanoparticles having metal oxide compositions are method advantageously provides a microbial-mediated Syn increasingly being used in numerous emerging applications. thesis of metal oxide nanoparticles wherein the microbial Some of these include the use of magnetic nanoparticles (e.g., process is economical, convenient, and environmentally magnetite) in magnetic refrigeration or magnetic cooling cir friendly. The method also provides substantially pure nano cuits Ferrite-type nanoparticles, in particular, are being particle product bereft of microbial matter after precipitation intensely studied for their use in the fields of biomedicine, from metal-reducing microbes. In addition, the method per optics, and electronics. mits the particle size and/or morphology of the nanoparticles Current methods for the production of nanoscale ferrites 25 to be controlled. and other oxide ceramics generally entail calcining a precur Sor (e.g., a carbonate) at a high temperature, and then BRIEF DESCRIPTION OF THE DRAWINGS mechanical milling the calcined product to reduce the particle size. The process is energy and time intensive, generally FIG.1. A process diagram illustrating a preferred embodi difficult to control, and often requires several repetitions of 30 ment of the invention for forming mixed constituent crystal the process before a final product is obtained. line phase nanoparticles. Chemical processes, such as precipitation and sol-gel tech FIG. 2. A graph showing a generally inverse relationship niques, are also known for the production of metal oxide between Surfactant concentration and crystallite size for nine nanoparticles. However, these processes are typically more Surfactants, with data from a control batch shown for com expensive than mechanical milling, and also generally highly 35 parison. limited with respect to size or shape control of the resulting FIG. 3. A graph showing variation of crystallite size with particles. Often, a chemical or physical reduction step is Surfactant concentration for three selected Surfactants. needed to convert a metal oxide precursor to a metal oxide FIG. 4. Depiction of a preferred batch-type reactor useful product. In addition, these processes often require a mechani for the described method. cal milling step to break up agglomerates formed during the 40 FIG. 5. Depiction of a continuous-type reactor useful for reduction process. the described method. The microbial synthesis of metal oxide nanoparticles is known. See, for example, U.S. Pat. Nos. 6,444,453 and 7,060, DETAILED DESCRIPTION OF THE INVENTION 473. However, there are significant problems in the microbial process as currently practiced. For example, there is the dif 45 According to the invention, a reducible metal oxide com ficulty of obtaining pure nanoparticle product