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Method Article

Viral Nanoparticles for In vivo Tumor Imaging

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DOI:

10.3791/4352

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November 16th, 2012

 ,  ,  ,  ,  , 
1Department of Biomedical Engineering, Case Western Reserve University , 2Department of Biomedical Engineering, Radiology, and Materials Science and Engineering, Case Western Reserve University

In This Article

Summary

Plant viral nanoparticles (VNPs) are promising platforms for applications in biomedicine. Here, we describe the procedures for plant VNP propagation, purification, characterization, and bioconjugation. Finally, we show the application of VNPs for tumor homing and imaging using a mouse xenograft model and fluorescence imaging.

Abstract

The use of nanomaterials has the potential to revolutionize materials science and medicine. Currently, a number of different nanoparticles are being investigated for applications in imaging and therapy. Viral nanoparticles (VNPs) derived from plants can be regarded as self-assembled bionanomaterials with defined sizes and shapes. Plant viruses under investigation in the Steinmetz lab include icosahedral particles formed by Cowpea mosaic virus (CPMV) and Brome mosaic virus (BMV), both of which are 30 nm in diameter. We are also developing rod-shaped and filamentous structures derived from the following plant viruses: Tobacco mosaic virus (TMV), which forms rigid rods with dimensions of 300 nm by 18 nm, and Potato virus X (PVX), which form filamentous particles 515 nm in length and 13 nm in width (the reader is referred to refs. 1 and 2 for further information on VNPs).

From a materials scientist's point of view, VNPs are attractive building blocks for several reasons: the particles are monodisperse, can be produced with ease on large scale in planta, are exceptionally stable, and biocompatible. Also, VNPs are "programmable" units, which can be specifically engineered using genetic modification or chemical bioconjugation methods 3. The structure of VNPs is known to atomic resolution, and modifications can be carried out with spatial precision at the atomic level4, a level of control that cannot be achieved using synthetic nanomaterials with current state-of-the-art technologies.

In this paper, we describe the propagation of CPMV, PVX, TMV, and BMV in Vigna ungiuculata and Nicotiana benthamiana plants. Extraction and purification protocols for each VNP are given. Methods for characterization of purified and chemically-labeled VNPs are described. In this study, we focus on chemical labeling of VNPs with fluorophores (e.g. Alexa Fluor 647) and polyethylene glycol (PEG). The dyes facilitate tracking and detection of the VNPs 5-10, and PEG reduces immunogenicity of the proteinaceous nanoparticles while enhancing their pharmacokinetics 8,11. We demonstrate tumor homing of PEGylated VNPs using a mouse xenograft tumor model. A combination of fluorescence imaging of tissues ex vivo using Maestro Imaging System, fluorescence quantification in homogenized tissues, and confocal microscopy is used to study biodistribution. VNPs are cleared via the reticuloendothelial system (RES); tumor homing is achieved passively via the enhanced permeability and retention (EPR) effect12. The VNP nanotechnology is a powerful plug-and-play technology to image and treat sites of disease in vivo. We are further developing VNPs to carry drug cargos and clinically-relevant imaging moieties, as well as tissue-specific ligands to target molecular receptors overexpressed in cancer and cardiovascular disease.

Protocol

1. VNP (CPMV, BMV, PVX, and TMV) Propagation

  1. Set the indoor plant chamber controls to 15 hr of day (100% light, 25 °C, 65% humidity) and 9 hr of night (0% light, 22 °C, 60% humidity).
  2. Inoculate plants according to the timeline in Table 1.
CPMVPVX, TMV, and BMV
Day 0: Plant 3 cowpea seeds/pot.Day 0: Plant ~30 N. benthamiana seeds/pot. Fertilize once a week with 1 tablespoon fertilizer/5 L water.
Day 14: Re-pot N. benthamiana at 1 plant/pot.
Day 10: Infect leaves primary leaves with CPMV (5 μg/50 μl/leaf) by mechanical inoculation using a light dusting of carborundum.Day 28: Infect three to five leaves with PVX, TMV, or BMV (5 μg/50 μl/leaf) by mechanical inoculation using a light dusting of carborundum.
Day 20: Harvest leaves and store in -80 °C.Day 42: Harvest leaves and store in -80 °C.

Table 1. Timeline for growing, infecting, and harvesting leaves.

Note: only CPMV propagation is demonstrated as an example.

2. VNP (CPMV, BMV, PVX, and TMV) Purification

Note: All steps are carried out on ice or at 4 °C.

  1. Homogenize 100 g of frozen leaves in a standard blender using 2 volumes of cold buffer (see Table 2). Filter through 2-3 layers of cheesecloth.
  2. For PVX, adjust pH to 6.5 using 1 M HCl. Add 0.2% (w/v) ascorbic acid and 0.2% (w/v) sodium sulfite.
  3. Centrifuge crude plant homogenate at 5,500 x g for 20 min. Collect supernatant.
  4. For BMV, layer 25 ml of supernatant over 5 ml of 10% (w/v) sucrose solution. Centrifuge at 9,000 x g for 3 hr and resuspend pellets in 38.5% CsCl solution (w/v). Mix by shaking for 5 hr, then continue with step 2.12.
  5. Extract plant material by adding 0.7 volumes of 1:1 (v/v) chloroform:1-butanol. Stir mixture for 30-60 min.
  6. Centrifuge solution at 5,500 x g for 20 min. Collect the upper aqueous phase.
  7. Add NaCl to 0.2 M and 8% (w/v) PEG (MW 8,000). For TMV, also add 1% (v/v) Triton X-100. Stir for at least 1 hr, then let sit for at least 1 hr.
  8. Centrifuge solution at 15,000 x g for 15 min. Resuspend pellet in 10 ml of buffer. For PVX, add 0.1% β-mercaptoethanol and urea to 0.5 M.
  9. Centrifuge at 8,000 x g for 30 min and collect supernatant.
  10. Ultracentrifuge supernatant at 160,000 x g for 3 hr. Resuspend pellet in 5 ml buffer overnight.
  11. Prepare a 10-40% sucrose gradient using equal volumes of 10%, 20%, 30%, and 40% sucrose in buffer (heaviest first). Allow the gradient to equilibrate overnight at room temperature.
  12. Ultracentrifuge resuspended pellet over sucrose gradient at 100,000 x g for 2 hr (24 hr for BMV).
  13. Collect light scattering band and dialyze against buffer.
  14. Characterize the VNPs (below) and store at 4 °C. For long-term storage, store at -80 °C.
CPMV and TMV0.1 M potassium phosphate buffer (pH 7.0)
38.5 mM KH2PO4
61.5 mM K2HPO4
PVX0.5 M borate buffer (pH 7.8)
0.5 M boric acid
Adjust pH with NaOH
BMVSAMA buffer (pH 4.5)
250 mM sodium acetate
10 mM MgCl2
2 mM β-mercaptoethanol (add fresh)

Table 2. Buffers and their recipes for each VNP.

Note: only CPMV propagation is demonstrated as an example.

3. VNP (CPMV, BMV, PVX, and TMV) Characterization

  1. Perform UV/visible spectroscopy to determine the concentration of VNPs.
    1. Measure the absorbance of 2 μl of sample using a NanoDrop spectrophotometer.
    2. Determine the concentration of particles and dyes using the Beer-Lambert law (A=εcl, where A is the absorbance, ε is the extinction coefficient, c is the concentration, and l is the path length). The path length is 0.1 cm for the NanoDrop.
      The VNP-specific extinction coefficients are:
      CPMV: 8.1 cm-1mg-1ml (at 260 nm)
      PVX: 2.97 cm-1mg-1ml (at 260 nm)
      TMV: 3.0 cm-1mg-1ml (at 260 nm)
      BMV: 5.15 cm-1mg-1ml (at 260 nm)
  2. Analyze particles by size-exclusion fast protein liquid chromatography (FPLC).
    1. Using a Superose 6 size-exclusion column and the ÄKTA Explorer, load 50-100 μg of VNPs in 200 μl of 0.1 M potassium phosphate buffer (pH 7.0).
    2. Set detectors to 260 nm (nucleic acid), 280 nm (protein), and the excitation wavelength of any dyes attached.
    3. Run at a flow rate of 0.5 ml/min for 72 min.
    4. The elution profile and A260:A280 nm indicates whether the VNP preparation is pure and whether particles are intact and assembled.
      The following A260:280 ratios indicate a pure VNP preparation:
      CPMV: 1.8±0.1
      PVX: 1.2±0.1
      TMV: 1.1±0.1
      BMV: 1.7±0.1
  3. Perform denaturing (pre-cast NuPAGE) Bis-Tris polyacrylamide 4-12% gradient gel electrophoresis to analyze purity of preparation and conjugation to individual coat proteins.
    1. Add 3 ml of 4x LDS sample buffer to 10 μg of the particles in 9 μl of potassium phosphate buffer. Add an additional 1 μl of 4x LDS sample buffer and 3 μl of β-mercaptoethanol to BMV to reduce the high number of disulfide bonds.
    2. Incubate in heat block for 5 min at 100 °C.
    3. Load samples onto an SDS gel.
    4. Run samples at 200 V for 1 hr in 1x MOPS running buffer.
    5. Document the gel under UV light to visualize fluorescent coat proteins.
    6. For non-fluorescent protein, stain with Coomassie blue (0.25% (w/v) Coomassie Brilliant Blue R-250, 30% (v/v) methanol, 10% (v/v) acetic acid) for 1 hr.
    7. Destain with 30% methanol, 10% acetic acid overnight. Change the solution if required.
    8. Document the gel under white light.
  4. Analyze integrity of particles by transmission electron microscopy (TEM).
    1. Dilute samples to 0.1-1 mg/ml in 20 μl of DI water.
    2. Place 20 μl drops of the samples on Parafilm.
    3. Cover drops with a TEM grid and let sit for 2 min. Wick off the excess solution on the grid with filter paper.
    4. Wash grid by placing on a drop of DI water then wicking dry.
    5. Stain grid by placing on a 20 μl drop of 2% (w/v) uranyl acetate for 2 min. Wick off the excess stain with filter paper.
    6. Wash grid once more in water.
    7. Observe grid under a transmission electron microscope.

4. Chemical Conjugation of VNPs with PEG and Fluorophores, Purification, and Characterization

  1. For calculations for the reactions below, the molar mass of the VNPs are:
    CPMV: 5.6 x 106 g/mol
    PVX: 35 x 106 g/mol
    TMV: 41 x 106 g/mol
    BMV: 4.6 x 106 g/mol
  2. Conjugate dyes and PEG to surface lysines of CPMV and PVX using a one-step N-hydroxy succinimide coupling reaction: Add 2,500 molar equivalents (all molar excesses refer to molar excess per VNP) of Alexa Fluor 647 succinimidyl ester and 4,500 equivalents of NHS-PEG (M.W. 5,000) dissolved in DMSO to CPMV in 0.1 M potassium phosphate buffer. When working with PVX, add a 10,000 molar excess of NHS-dye and NHS-PEG. Adjust the buffer and DMSO volumes such that the final concentration of CPMV and PVX is 2 mg/ml and DMSO content is 10% of the total reaction volume. Incubate the reaction mixture overnight at room temperature protected from light. CPMV and PVX have 300 and 1,270 addressable lysines, respectively. (The reader is referred to the following references for further reading on chemical modification of CPMV and PVX: 13-15).
  3. Conjugate dyes and PEG to tyrosines of TMV by diazonium coupling followed by copper(I)-catalyzed azide-alkyne cycloaddition.
    1. Prepare diazonium salt (alkyne) by mixing 400 μl of 0.3 M p-toluenesulfonic acid monohydrate, 25 μl of 3.0 M sodium nitrite, and 75 μl of 0.68 M distilled 3-ethynylaniline dissolved in acetonitrile at 4 °C for 1 hr.
    2. Add 3.3 ml of borate buffer, pH 8.8, containing 100 mM NaCl to 1.25 ml of TMV (20 mg/ml stock solution).
    3. React the TMV with 450 μl of the diazonium salt (alkyne) solution in an ice bath for 3 hr to add an alkyne ligation handle to TMV by diazonium coupling. The solution will turn into a light brown color. TMV has 2,140 available tyrosines for conjugation.
    4. Purify the final product using a sucrose cushion as described in step 4.4.
    5. Attach azide-functional Alexa Fluor 647 and PEG-azide (M.W. 5,000) using copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Add 2 equivalents of dye- and PEG-azide per coat protein and incubate with 1 mM CuSO4, 2 mM AMG, and 2 mM sodium ascorbate at room temperature for 15 min. Adjust the buffer volume such that the final reaction concentration of TMV is 2 mg/ml. (The reader is referred to the following references for further reading on chemical modification of TMV: 16,17).
  4. Conjugate dyes to lysines and PEG to cysteines of BMV cysteine mutant (cBMV):
    1. Add 2,000 molar equivalents of Oregon Green 488 succinimidyl ester dissolved in DMSO to cBMV in 0.1 M TNKM buffer (50 mM Tris base, 50 mM NaCl, 10 mM KCl, 5 mM MgCl2, pH 7.4). Adjust the buffer and DMSO volumes such that the final concentration of BMV is 1 mg/ml and DMSO content is 10% of the total reaction volume. Incubate the reaction mixture overnight at 4 °C protected from light.
    2. Purify particles using centrifugal filters as described in step 4.4.
    3. Add 2,000 molar excess of PEG-maleimide (M.W. 2,000) using the same reaction conditions as before and incubate the reaction mixture for 2 hr at 4 °C. cBMV has 180 reactive lysines and cysteines. (The reader is referred to the following references for further reading on chemical modification of BMV:18).
  5. Purification: Pass the solution through a 40% (w/v) sucrose cushion at 160,000 x g for 2.5 hr. Re-dissolve the pellet in buffer. Alternatively, dialyze against appropriate buffer using 10 kDa cut-off spin filters.
  6. Characterization: PEGylated and fluorescently-labeled VNPs are analyzed using the above-described methods: UV/visible spectroscopy, SDS gel electrophoresis, FPLC, and TEM (not shown, however, refer to Figures 6 and 7) .

5. Tumor Targeting and Imaging using a Mouse Xenograft Model

  1. Culture HT-29 human colon cancer cells in RPMI medium supplemented with 5% FBS, 1% penicillin-streptomycin, and 1% L-glutamine at 37 °C in 5% CO2 using 175 cm2 cell culture flasks.
  2. Wash cells twice with sterile PBS and harvest by incubating with 5 ml of trypsin-EDTA at 37 °C for 5 min. Inactivate the trypsin with 5 ml of RPMI medium. Collect cells by centrifuging at 500 x g for 5 min. at 4 °C and resuspend in fresh RPMI at 5x106 cells/50 μl medium (determine total cell count using trypan blue and a hemocytometer). Mix with an equal volume of matrigel prior to injection (keep all solutions and reagents sterile).
  3. Procure six-week old NCR nu/nu mice and maintain them on an alfalfa free diet for 2 weeks. [Note: all animal procedures must be IACUC approved.] Induce tumor xenografts by subcutaneous injection of 5x106 cells/100 μl/tumor in the flanks (2 tumors/mouse) using an 18 1/2 gauge sterile needle. Monitor the animals regularly. Measure the tumor size using calipers and allow the tumors to grow to an average volume of 20 mm3 (within the next 12 days). Assign mice to two different groups randomly: PBS and VNP (n = 3 animals/group/time point). Using a 1 ml 28 gauge insulin syringe, administer by intravenous tail vein injection 100 μl of sterile PBS or 10 mg/kg VNP formulation.

Note: Tissue culture experiments and studies with live animals will not be demonstrated. Hands-on demonstration will be limited to tissue processing and data acquisition. For a reference on the HT-29 tumor xenograft model, the reader is referred to ref. 19

Three techniques are used to evaluate tumor homing of VNPs:

  1. Fluorescence imaging using Maestro Imaging System: Sacrifice mice at different time points (2, 24, and 72 hr) using CO2 gas. Dissect the animals and excise all major organs (brain, heart, lungs, spleen, kidneys and liver) along with the tumors on the flanks, place the tissues on parafilm, and analyze with fluorescence imaging instrument using yellow excitation and emission filters (800 ms exposure) to detect the presence of fluorescent signals in the tissues (derived from A647 label conjugated to the VNPs). Save the images and analyze fluorescent intensities using ImageJ 1.44o software (http://imagej.nih.gov/ij). Compare the pattern of uptake of the VNPs in tumors with other major tissues with time.
  2. After imaging, cut each tissue in half and embed one half in OCT compound for cryo-sectioning and confocal analysis. Collect the other half in pre-weighed cryo-vials and immediately freeze them using liquid N2. Store at -80 °C until ready for further processing.
  3. Fluorescence quantification: Record tissues weights. Thaw frozen tissues at room temperature and place them in separate 50 ml Falcon tubes containing 1 ml of PBS. Using a handheld tissue homogenizer, homogenize the tissues for 2-3 min in PBS then transfer the homogenate to microfuge tubes. Centrifuge the homogenates for 10 min at 13,000 x g to remove non-homogenized tissue.
  4. Pipet 100 μl of the supernatant from the tissues from each group (PBS and VNP formulations/time points) into a 384 well black UV plate. Evaluate fluorescence intensity (Ex/Em wavelengths 600/665) using a plate reader. Normalize the obtained fluorescent values by the tissue weights.
  5. Immunohistochemistry: Prepare cryo-microtome sections (10 μm) and store at -20 °C. Stain tissue sections for cell nuclei (DAPI) and endothelial cell marker (FITC-labeled anti-mouse CD31 antibody). Carry out confocal microscopy analysis to map the vascular and intra-tumoral localization of fluorescently-labeled VNPs.

Note: This procedure will not be demonstrated, representative data are shown in Figure 8. For a reference on immunohistochemistry and the described staining methods, the reader is referred to ref. 19

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Results

Plant growth comparative analysis; experimental setup, study of leaf color variation, chlorosis method.
Figure 1. Plant virus-infected plants. Vigna unguiculata plants infected with CPMV (A). Nicotiana benthamiana plants infected with PVX (B), TMV (C), and BMV (D). The pictures were taken about 10 days post infection by mechanical inocula...

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Discussion

This protocol provides an approach for the chemical modification of VNPs and their applications for in vivo tumor imaging. The animal fluorescence imaging, fluorescence quantification, and immunohistochemistry techniques presented here are useful for studying biodistribution and evaluating tumor homing. These techniques provide valuable information regarding access of the nanoparticles to the tumor via the EPR effect. By combining the results from the various analytical methods, we get a powerful approach for ev...

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Disclosures

No conflicts of interest declared.

Acknowledgements

This work was supported by NIH/NIBIB grants R00 EB009105 (to NFS) and P30 EB011317 (to NFS), a NIH/NIBIB training grant T32 EB007509 (to AMW), a Case Western Reserve University Interdisciplinary Alliance Investment Grant (to NFS), and a Case Comprehensive Cancer Center grant P30 CA043703 (to NFS). We thank the Steinmetz Lab undergraduate student researchers for their hands-on support: Nadia Ayat, Kevin Chen, Sourav (Sid) Dey, Alice Yang, Sam Alexander, Craig D'Cruz, Stephen Hern, Lauren Randolph, Brian So, and Paul Chariou.

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
VNP production
Indoor plant chamberPercival ScientificE-41L2
V. unguiculata seeds (California black-eye no. 5)Burpee51771A
N. benthamiana seedsN. benthamiana seeds were a gift from Salk Institute. Seeds are produced through plant propagation.
CarborundumFisherC192-500
Pro-mix BX potting soilPremier Horticulture713400
Jack's Professional 20-10-20 Peat-Lite FertilizerJR Peters77860
Equipment
50.2 Ti rotorBeckman337901
SW 32 Ti rotorBeckman369694
Optima L-90K ultracentrifugeBeckman365672
SLA-3000 rotorThermo Scientific07149
SS-34 rotorThermo Scientific28020
Sorvall RC-6 Plus centrifugeThermo Scientific46910
Polypropylene bottleBeckman355607For SLA-3000 rotor
Polycarbonate bottleBeckman357002For SS-34 rotor
Ultra-Clear tubeBeckman344058For sucrose gradient and SW 32 Ti rotor
Polycarbonate bottleBeckman355618For pelleting and 50.2 Ti rotor
NanoDrop spectrophotometerThermo ScientificNanoDrop2000c
PowerEase 500 pre-cast gel systemInvitrogenEI8675EU
Superose 6 10/300 GL (24 ml) size-exclusion columnGE Healthcare17-5172-01
ÄKTA Explorer 100 ChromatographGE Healthcare28-4062-66
Allegra X-12RBeckman392302Benchtop centrifuge
CryostatLeicaCM1850
Maestro 2Caliper Life SciencesIn vivo imaging system
Tissue-TearorBiospec Products985370-395
Microplate readerTecanInfinite-200
Transmission electron microscopeZEISSLibra 200FE
FluoView laser scanning confocal microscopeOlympusFV1000
Chemicals and Reagents
3-ethynylanilineSigma Aldrich498289-5G
384 well black plateBD Biosciences353285
4-12% Bis-Tris NuPAGE SDS gelInvitrogenNP0321BOX
4X LDS sample bufferInvitrogenNP0008
Acetic AcidFisherA385-500
AcetonitrileSigma Aldrich271004-1L
Alexa Fluor 647 azideInvitrogenA10277
Alexa Fluor 647 carboxylic acid, succinimidyl esterInvitrogenA20006
Amicon Ultra-0.5 ml Centrifugal FiltersMilliporeUFC50109610 kDa cut-off
Aminoguanidine hydrochlorideAcros Organics36891-0250
Boric acidFisherA74-500
Coomassie Brilliant Blue R-250FisherBP101-25
CsClAcros Organics42285-1000
DAPIMP Biomedicals157574
Dimethyl sulfoxideFisherBP231-100
Filter paperFisher09-801KP5 grade
FITC anti-mouse CD31BioLegend102406
Goat serumInvitrogen16210-064
KClFisherBP366-500
L-ascorbic acid sodium saltAcros Organics35268-0050
MethanolFisherA412P-4
MgCl2FisherBP214-500
Microscope slidesFisher12-544-3
Microscope cover glassVWR48366-277
MOPS bufferInvitrogenNP0001
mPEG-malNanocsPG1-ML-2kMW 2000
mPEG-N3NanocsPG1-AZ-5kMW 5000
mPEG-NHSNanocsPG1-SC-5kMW 5000
NaClFisherBP358-212
Oregon Green 488 succinimidyl ester *6-isomer*InvitrogenO-6149
p-toluenesulfonic acid monohydrateAcros Organics13902-0050
PermountFisherSP15-100
Potassium phosphate dibasicFisherBP363-1
Potassium phosphate monobasicFisherBP362-1
Sodium acetateFisherBP333-500
Sodium nitriteAcros Organics42435-0050
Sodium sulfiteAmresco0628-500G
SucroseFisherS6-500
TEM gridTed PellaFCF-400Cu
Tris baseFisherBP152-500
Triton X-100EMD ChemicalsTX1568-1
β-mercapt–thanolFisherO3446I-100
Tissue Culture
Fetal bovine serumInvitrogen12483-020
HemocytometerFisher0267110
HT-29 cellsATCCHTB-38
L-glutamineInvitrogen25030-080
PBSCellgro21-040-CV
Penicillin-streptomycinInvitrogen10378-016
RPMI-1640Invitrogen31800-089
Tissue culture flasksCorning431080175 cm2
Trypan BlueThermo ScientificSV30084.01
Trypsin, 0.05% (1X) with EDTA 4Na, liquidInvitrogen25300-054
Animal Studies
18% Protein Rodent DietHarlan TekladTeklad Global 2018SAlfalfa free diet
Insulin syringeBD Biosciences32941028 gauge
IsofluraneBaxterAHN3637
Matrigel Matrix basement membraneBD Biosciences356234
NCR nu/nu miceCWRU School
of Medicine Athymic Animal and Xenograft Core Facility
Sterile syringeBD Biosciences30519618 1/2 gauge
Tissue-Tek CRYO-OCT CompoundAndwin Scientific4583

References

  1. Description of Plant Viruses [Internet]. , Association of Biologists. Warwick, UK. Available from: http://dpvweb.net/ (2012).
  2. Carrillo-Tripp, M., Shepherd, C. M., Borelli, I. A., Venkataraman, S., Lander, G., Natarajan, P., Johnson, J. E., Brooks, C. L., Reddy, V. S. VIPERdb2: an enhanced and web API enabled relational database for structural virology. Nucl. Acids Res. 37, 436-442 (2009).
  3. Pokorski, J. K., Steinmetz, N. F. The art of engineering viral nanoparticles. Mol. Pharm. 8, 29-43 (2011).
  4. Steinmetz, N. F., Lin, T., Lomonossoff, G. P., Johnson, J. E. Structure-based engineering of an icosahedral virus for nanomedicine and nanotechnology. Curr. Top Microbiol. Immunol. 327, 23-58 (2009).
  5. Jung, B., Rao, A. L., Anvari, B. Optical Nano-Constructs Composed of Genome-Depleted Brome Mosaic Virus Doped with a Near Infrared Chromophore for Potential Biomedical Applications. ACS Nano. , (2011).
  6. Leong, H. S., Steinmetz, N. F., Ablack, A., Destito, G., Zijlstra, A., Stuhlmann, H., Manchester, M., Lewis, J. D. Intravital imaging of embryonic and tumor neovasculature using viral nanoparticles. Nat. Protoc. 5, 1406-1417 (2010).
  7. Leopold, P. L., Ferris, B., Grinberg, I., Worgall, S., Hackett, N. R., Crystal, R. G. Fluorescent virions: dynamic tracking of the pathway of adenoviral gene transfer vectors in living cells. Hum. Gene Ther. 9, 367-378 (1998).
  8. Lewis, J. D., Destito, G., Zijlstra, A., Gonzalez, M. J., Quigley, J. P., Manchester, M., Stuhlmann, H. Viral nanoparticles as tools for intravital vascular imaging. Nat. Med. 12, 354-360 (2006).
  9. Steinmetz, N. F., Ablack, A. L., Hickey, J. L., Ablack, J., Manocha, B., Mymryk, J. S., Luyt, L. G., Lewis, J. D. Intravital imaging of human prostate cancer using viral nanoparticles targeted to gastrin-releasing Peptide receptors. Small. 7, 1664-1672 (2011).
  10. Wu, C., Barnhill, H., Liang, X., Wang, Q., Jiang, H. A new probe using hybrid virus-dye nanoparticles for near-infrared fluorescence tomography. Optics Communications. 255, 366-374 (2005).
  11. Steinmetz, N. F., Cho, C. F., Ablack, A., Lewis, J. D., Manchester, M. Cowpea mosaic virus nanoparticles target surface vimentin on cancer cells. Nanomedicine (Lond). 6, 351-364 (2011).
  12. Maeda, H., Wu, J., Sawa, T., Matsumura, Y., Hori, K. Tumor vascular permeability and the EPR effect in macromolecular therapeutics: a review. Journal of Controlled Release. 65, 271-284 (2000).
  13. Chatterji, A., Ochoa, W., Paine, M., Ratna, B. R., Johnson, J. E., Lin, T. New addresses on an addressable virus nanoblock: uniquely reactive Lys residues on cowpea mosaic virus. Chem. Biol. 11, 855-863 (2004).
  14. Steinmetz, N. F., Mertens, M. E., Taurog, R. E., Johnson, J. E., Commandeur, U., Fischer, R., Manchester, M. Potato virus X as a novel platform for potential biomedical applications. Nano Lett. 10, 305-312 (2010).
  15. Wang, Q., Lin, T., Tang, L., Johnson, J. E., Finn, M. G. Icosahedral virus particles as addressable nanoscale building blocks. Angew. Chem. Int. Ed. 41, 459-462 (2002).
  16. Bruckman, M. A., Kaur, G., Lee, L. A., Xie, F., Sepulveda, J., Breitenkamp, R., Zhang, X., Joralemon, M., Russell, T. P., Emrick, T., Wang, Q. Surface modification of tobacco mosaic virus with "click" chemistry. Chembiochem. 9, 519-523 (2008).
  17. Schlick, T. L., Ding, Z., Kovacs, E. W., Francis, M. B. Dual-surface modification of the tobacco mosaic virus. J. Am. Chem. Soc. 127, 3718-3723 (2005).
  18. Yildiz, I., Tsvetkova, I., Wen, A. M., Shukla, S., Masarapu, M. H., Dragnea, B., Steinmetz, N. F. Engineering of Brome mosaic virus for biomedical applications. RSC Advances. , (2012).
  19. Brunel, F. M., Lewis, J. D., Destito, G., Steinmetz, N. F., Manchester, M., Stuhlmann, H., Dawson, P. E. Hydrazone ligation strategy to assemble multifunctional viral nanoparticles for cell imaging and tumor targeting. Nano Lett. 10, 1093-1097 (2010).
  20. Shukla, S., Ablack, A., Wen, A., Lee, K., Lewis, J., Steinmetz, N. F. Increased tumor homing and tissue penetration of the filamentous plant viral nanoparticle Potato virus X. Molecular Pharmaceutics. , (2012).
  21. Chatterji, A., Ochoa, W., Shamieh, L., Salakian, S. P., Wong, S. M., Clinton, G., Ghosh, P., Lin, T., Johnson, J. E. Chemical conjugation of heterologous proteins on the surface of Cowpea mosaic virus. Bioconjug. Chem. 15, 807-813 (2004).

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