Grantee Research Project Results
2002 Progress Report: A Bioengineering Approach to Nanoparticle based Environmental Remediation
EPA Grant Number: R829601Title: A Bioengineering Approach to Nanoparticle based Environmental Remediation
Investigators: Strongin, Daniel R. , Schoonen, Martin A.A. , Douglas, Trevor
Current Investigators: Strongin, Daniel R. , Douglas, Trevor , Schoonen, Martin A.A.
Institution: Temple University , Montana State University , The State University of New York at Stony Brook
Current Institution: Temple University , The State University of New York at Stony Brook , Montana State University
EPA Project Officer: Hahn, Intaek
Project Period: February 1, 2002 through January 31, 2005
Project Period Covered by this Report: February 1, 2002 through January 31, 2003
Project Amount: $399,979
RFA: Exploratory Research: Nanotechnology (2001) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Nanotechnology , Safer Chemicals
Objective:
The objective of this research project is to develop a bioengineering approach that can be used to develop nano-sized catalytic materials as the basis for new remediation strategies. We are investigating the use of ferritin, and ferritin-derived compounds, as catalysts in environmental degradation processes. The management of anthropogenic chemical toxins is a major environmental challenge. Various strategies have been employed to facilitate the degradation of this class of pollutants. Processes involving nano-sized materials have garnered interest because it is well known that nano-sized particles exhibit unusual thermal and photochemistry in a variety of chemical applications, when compared to particles of larger dimensions.
The ferritin system has the advantage of being environmentally benign and biodegradable. Ferritin is an iron-storage protein that consists of a native nano-size iron oxide core (ferrihydrite), encapsulated within a spherical protein cage (120 Å diameter). Ferritin is commercially available, but it also has been cloned in our laboratory and can be produced in gram quantities. We have shown that the size of the iron oxide particles can be controlled to form homogeneous nanoparticles from 20 to 75 Å. Also, the native iron oxide core of ferritin can be replaced by other metal oxides, such as Mn and Co oxides. Such inorganic materials, at more traditional size ranges (> micron), exhibit photocatalytic and catalytic activity in a variety of systems. Our hypothesis is that by assembling these materials as nanoparticles within the ferritin (i.e., the protein shell), we can "tune" their surface chemistry toward beneficial environmental chemistry through our control of their size and electronic structure.
Progress Summary:
Results Using Horse Spleen (HS_Fn) Ferritin
Reduction of CrO42-. HS_Fn is a 24 subunit protein of roughly spherical shape, with outer and inner diameters of approximately 12 and 8 nm, respectively. The native mineral core of ferritin is the ferric oxyhydroxide ferrihydrite (Fe(O)OH). Fe(O)OH particles, which ranged from 5 to 7.5 nm in diameter, were used in the experiments. The ferritin protein without the Fe(O)OH core (i.e., apoferritin) was inactive toward Cr(VI) reduction under our experimental conditions, suggesting that the Fe(O)OH provided the active catalytic sites in the redox chemistry. Experiments using photon band-pass filters suggested that the reaction occurred out of a photo-induced electron-hole pair and the optical band gap for the Fe(O)OH semiconductor was determined to be in the range 2.5-3.5 eV. Comparison of ferritin and protein-free Fe(O)OH mineral nanoparticles indicated that ferritin provided a photocatalyst with significantly more stability to aggregation and the loss of catalytic activity.
Results Using the 12-Subunit Ferritin-Like Protein Cage From Listeria innocua (Lis_Fn). The photo-catalytic reduction of Cr(VI), observed in the presence of Fe2O3 mineralized horse spleen ferritin (HS_Fn), also has been observed in the ferritin-like protein isolated from Lis_Fn.
Protein Isolation Characterization. This protein differs from HS_Fn in that it assembles from only 12 identical subunits (rather than 24 subunits as in HS_Fn). This results in a smaller protein cage, with a 9 nm outer diameter, and an internal cavity 5 nm in diameter. This protein can mineralize a maximum of 500 Fe atoms as a particle of Fe2O3. We have successfully cloned this protein into an Escherichia coli expression system and have isolated purified protein from this over-expression system. The purified protein has been characterized by size exclusion chromatography, dynamic light scattering, zeta potential, and transmission electron microscopy. The mineralized protein is highly stable and can be heated to 70°C before aggregation or degradation of the protein occurs.
Mineralization of the Lis_Fn With Co-Oxides. We also have shown that the mineralization of the Lis_Fn can be achieved using Co rather than Fe. Thus, reaction of the Lis_Fn protein cage with Co(II) and H2O2 at pH 8.5, results in the formation of a Co-oxyhydroxide (Co(O)OH) when reacted at room temperature, and in a Co-oxide spinel phase (Co3O4) when the reaction was performed at 65°C. These materials are both green in color, with an absorption edge shifted to lower energy (~450nm) as compared to the Fe oxide materials (~350nm). This might have implications for the use of these as catalysts with a more substantial excitation in the visible region of the spectrum.
Photoreduction of CrO42- in the Presence of Fe2O3-Loaded Lis_Fn. Initial results show that the photolysis of CrO42-, in the presence of the Fe2O3, mineralized Lis_Fn (with tartrate as a sacrificial reductant) results in a rapid decrease in the charge transfer absorbance of the CrO42- at 370 nm. This is because of the reduction of Cr(VI) to Cr(III).
Future Activities:
Future activities will be to continue our investigations of the photochemical activity of ferritin. Specific systems will involve both Cr and As redox chemistry. Experiments also are planned to begin to use ferritin to produce nano-size zero valent Fe, and to investigate the utility of these small metal particles on chlorocarbon decomposition.
In the next project period we will continue our investigations of the charge development and band edge position of nanosemiconductor particles derived from ferritin. Specifically, efforts will be focused on the following topics: (1) determination of surface charge of ferritin as a function of solution composition; (2) determination of bandgap and position of band edges of ferritin core; and (3) evaluation of possible photocatalytical activity of ferritin in decomposition of model organic compound dissolved in water.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 26 publications | 7 publications in selected types | All 3 journal articles |
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Type | Citation | ||
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Kim I, Hosein H-A, Strongin DR, Douglas T. Photochemical reactivity of ferritin for Cr(VI) reduction. Chemistry of Materials 2002;14(11):4874-4879. |
R829601 (2002) R829601 (Final) |
not available |
Supplemental Keywords:
nanotechnology, environmental chemistry, remediation, soil, water, chemicals, toxics, organics, metals, solvents, photocatalysis., RFA, Scientific Discipline, Waste, Water, Sustainable Industry/Business, Sustainable Environment, Physics, Environmental Chemistry, Remediation, Technology for Sustainable Environment, New/Innovative technologies, Bioremediation, Environmental Engineering, Engineering, Chemistry, & Physics, nanoparticle remediation, decontamination, bioengineering, nanoscale biopolymers, wastewater, biodegradation, remediation technologies, nanotechnology, environmental sustainability, bio-engineering, nanocatalysts, groundwater remediation, aquifer remediation design, environmentally applicable nanoparticles, biotechnology, sustainability, groundwater contamination, biochemistry, contaminated aquifers, innovative technologies, cadmium, nanoparticle based remediationProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.