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A Bioengineering Approach to Environmental Remediation
Daniel Strongin1, Trevor Douglas2, and Martin A. Schoonen3
(1) Department of Chemistry, Temple University, 1901 N. 13th St., Philadelphia, PA (2) Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT
(3) Department of Geosciences, SUNY-Stony Brook, Stony Brook, NY
R829601
ACS-PRF
Acknowledgments
Hazel-Ann Hosein - Temple Univ.Mark Allen - Montana State Univ.Dan Ensign - Montana State Univ.
Horse Spleen Ferritin (HSF)
Listeria Innocua Ferritin-like Protein (LFLP)
• 24 polypeptide subunits
• Spherical protein cage (120 Å dia.)
• Cavity (80 Å dia.)
• Accommodates up to 4500 Fe atoms
Stores Fe as hydrated Fe2O3 (rust)
• 12 polypeptide subunits
• Spherical protein cage (90 Å dia.)
• Cavity (56Å dia.)
• Accommodates up to 500 Fe atoms
12 distinct sites10 Glu residues (at each site)
Glutamate (COO—)
N
N
N
N
N
N
RuII
HN
OS
Ru(phen)(bpy)22+ covalently linked to HSP G41C = photosensitizer
Small Heat Shock Protein Cage
From the thermophile
Cloned Mutant used
24 subunit cage with large 3nm
Diameter pores
Ferritin as a (photo)catalyst
Ferritin as a Template forThe growth of oxide and Metallic nanoparticles
Functionalization of the ferritin shell
Goals of EPA - Funded Research
2Fe2+ + Prot Prot-[Fe2]O2
Prot-[Fe2–O2]
Prot-[Fe-O-Fe]
H2O2
H2O, H+
2Fe2+ + O2
Fe(O)OH(s)
H2O2
2Fe(O)OH + 4 H+ Ferroxidase catalysed (important early on in the mineralization process )
4Fe2+ + O2 4Fe(O)OH + 2H2O + 8 H +Mineral catalysed (autocatalytic Fe(II) oxidation and hydrolysis
Fe Fe
O––O
OC
OO
CO
Hwang, J., Krebs, C., Huynh, B. H., Edmondson, D. E., Theil, E. C. & Penner-Hahn, J. E. (2000). Science 287, 122
TiO2 vs. Ferric oxides
TiO2
Bandgap=3.2 eV uv lamps needed to
maximize photochemistry
very high stability
Ferric oxides (e.g., FeOOH
Bandgap=2.2 - 2.8eV can utilize a significant
part of solar spectrum low stability -
photocorrosion
Xenon vs. Solar spectrum
Xenon: The Full Spectrum vs. Deuterium Plus Tungsten by Robert A. Capobianco, http://opto.perkinelmer.com/library/papers/tp9.asp
TiO2
FeOOH
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0.0D
ecr
ea
se o
f th
e A
bso
rba
nce
at
37
2n
m
20151050
Time, min
a
b
c
The decrease of the absorbance at 372 nm. The final concentration of the species: Na2Cr2O7: 5x10-6M; tartrate: 3x10-2M; Ferritins: 0.25mg/ml; Buffer: 0.1M. Tris, pH8.5.a, CoOOH-Fn; b, MnOOH-Fn; c, FeOOH-Fn.
Cr(VI) Cr(III)
lightCr2O7
2- + 14H+ + 6e- 2Cr3+ 7H2O
Can we tailor a nanoparticle system having a bandgap In the visible with high stability for application in environmental remediation?
Stability of catalytic ferritin particles
Time (min)0 50 100 150 200 250 300
ln[C
r(V
I)/C
r(V
I)o
]
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
5:110:115:120:1
Cr:Fe
Reductant – tartrate (3.2x10-3 M)
Cr2O72- (4.0x10-4 M)
pH 7.5, tris buffer
Photocorrosion and aggregation of protein free FeOOH
h
Fe(II)O2 , H+
Insoluble precipitate
h
Fe(II)Fe(III)
O2
Ferritin system
Ferritin as a Template forThe growth of oxide and Metallic nanoparticles
Apo-Ferritin
120
80
Ferritin Fe(O)OH
Co(O)OH Mn (O)OH Fe(O)OH
Fe Co
Reduction
Loading ofmetal controlsultimate nanoparticlesize
UV-Ozone treatment
Reduction
General synthetic scheme for Fe metal production
The PSD-UV uses high intensity UV radiation to vaporize and remove the protein portion
The high pressure cell coupled to UHV chamber where reduction of metal oxide to metal occurs and accompanying transfer apparatus.
Heights (nm
0.5 1 1.5 2 2.5 3 3.5
Fre
qu
en
cy
0
5
10
15
20
FeOOH nanoparticles prepared by UV-ozone treatment of 100 Fe loaded ferritin for 60 mins at 100oC under oxygen (<5psi)
ISOLATED NANOPARTICLES
Average Height ONLY 2.5 nm!
Acoustic AC mode AFM Characterization of FeOOH nanoparticles
Relative height distribution of particles
AC Mode AFM Images: Apoferritin + FeFn mixturesApoferritin + 500 FeFn mixture Apoferritin + 2000 FeFn mixture
TM-AFM Characterizationof Iron nanoparticles
• ISOLATED NANOPARTICLES• Peak-to-valley height differences for the large features in the cross-section are in the 4-6 nm range.
• Full range of height values = 8.0 nm
• RMS roughness = 1.47 nmFe nanoparticles prepared by heating FeOOHnanoparticles in H2.
Height mode; 286 x 286 nm
TM-AFM Characterization
of Co3O4 nanoparticles
Height mode; 235 x 235 nm
Co3O4 nanoparticles on SiO2 prepared by UV-ozone treatment of LFLP for 1 hr at 100oC under oxygen (<5psi)
Narrow Distribution of particle sizes: 2.5-3.0 nm
RMS roughness = 1.07 nm
citrate
Cu2+ Cuº
1.5
1.0
0.5Ab
sorb
an
ce
900800700600500Wavelength, nm
D. Ensign, M. Young, T. Douglas Inorg. Chem (2004)
Photocatalytic Synthesis of Cu nanoparticles
QuickTime™ and aGIF decompressor
are needed to see this picture.
Cu2+
e-
h+
h
Cu0
Fe(O)OH
1) 2)
15
10
5
0
nu
mb
er
of
part
icle
s
20151050diameter, nm
500 Cu:ferritin
6
5
4
3
2
1
0n
um
ber
of
part
icle
s
6050403020100diameter, nm
2000 Cu:ferritin
500 Cu/Fn 2000 Cu/Fn
9.7 ± 3 nm 31 ± 8 nm
QuickTime™ and aGIF decompressor
are needed to see this picture.
As(III) addition
2.5 m
200 nm
200 nm
Wide scan
Insolubleprecipitate
Sequestration ofAqueous As(III) byFeOOH nanoparticles
FeOOH NanoparticlesSupported on Si wafer
Atomic Force Microscopy
No nanoparticlesNo precipitate
Visible Light-Induced Production of Singlet OxygenGround triplet state 3g
First excited singlet state 1g
Second excited singlet state 1g
relax-
ation
2s
* 2s 2p
* 2p* 2p 2p
3g
1 g
1g
h
96.5 kJ/mol
h
254 kJ/mol
1GS
1MLCT3MLCT
Eh
3O2
1O2
photosensitizer
Why?• Delivery of photosensitizers to cells
• Illumination produces 1O2
• 1O2 is about 1 V more oxidizing than 3O2
Functionalization of the ferritin
Visible Light-Induced Production of Singlet Oxygen
N
N
N
N
N
N
RuII
HN
OS
Ru(phen)(bpy)22+ covalently linked to HSP G41C = photosensitizer
h
3O2
1O2
Excitation of the Ru(II)-HSP complex increases the rateOf singlet oxygen production by a factor of 50 comparedTo the Ru(II) complex alone!
SUMMARYFerritin facilitates
Reduction of Cr(VI) to Cr(III)
Ferritin as a Template for the growth of oxide and metallic nanoparticlesFe and Co oxides / Fe, Co, and Cu metals
Functionalization of the ferritin-like protein shell to form photosensitizer
Acknowledgments
Hazel-Ann Hosein - Temple Univ.Mark Allen - Montana State Univ.Dan Esign - Montana State Univ.