Functionalised silicon nanoparticles

Abstract

The present invention is related to silicon nanoparticles, a pharmaceutical composition comprising silicon nanoparticles, a method for synthesis of the silicon nanoparticles and their use for in vivo diagnostics, visualization of drug delivery or staining of cells, biological processes or pathways. The silicon nanoparticles are characterized that they comprise a silicon core of a size of 1 to 10 nm and are terminated with allylamine or poly(allylamine) comprising up to 10 allylamine groups.

Claims

1. A silicon nanoparticles characterised in that they comprise a bioinert silicon core of a size of 1 to 10 nm and are terminated with allylamine or poly(allylamine) comprising up to 10 allylamine groups, wherein a. the nanoparticle's surface is mono-functionalised or multi-functionalised with a functional group visualizable using X-ray, MRI, ultrasound or microwave, or optical imaging involving luminescence or fluorescence, CT, PET, or SPECT; and b. the functionalized group is selected from the group comprising a luminescent compound, a fluorescent compound, a light absorbing compound, a radioactive compound, a metal compound that can be visualized using x-rays, a compound that can be visualized using magnetic resonance imaging (MRI), a compound that can be visualized using ultrasound or microwave, a luminescent/fluorescent material that can be utilized in optical imaging, an X-ray contrast-giving agent that can be imaged by computed tomography (CT) and an isotope that can be imaged by positron emission tomography (PET) or single photon emission computed tomography (SPECT); and c. the nanoparticle's surface is bound to targeting molecules and/or therapeutically relevant molecules selected from the group comprising toxins, radionuclides and chemotherapeutics.

2. The silicon nanoparticles according to claim 1, wherein the X-ray contrast-giving agent comprises, iodinated compounds or gadolinium based compounds.

3. The silicon nanoparticles according to claim 1, wherein the nanoparticles are coated with at least one of proteins, lipids, surfactants, perfluoropropane or sulphur hexafluoride.

4. The silicon nanoparticles according to claim 1, wherein the contrast-giving material comprises at least one paramagnetic material selected from the group comprising rare earth, gadolinium, manganese, iron and copper complexes.

5. The silicon nanoparticles according to claim 1, wherein the contrast-giving agent for X-ray computed tomography comprises barium salts and/or polyoxometalates.

6. The silicon nanoparticles according to claim 1, wherein the isotopes that can be imaged by positron emission tomography are selected from the group comprising .sup.64Cu, .sup.68Ga, .sup.86Y, .sup.89Zr, .sup.110In or .sup.18F based tracer.

7. The silicon nanoparticles according to one of claim 1, wherein the isotopes that can be imaged by single photon emission computed tomography are selected from the group comprising .sup.67Ga, .sup.99mTc, .sup.111In or .sup.201Tl.

8. The silicon nanoparticles according to claim 1, comprising at least one biomolecule selected from the group comprising a peptide, a protein, a sugar molecule, a nucleic acid or nucleic acid analogue bound to the nanoparticle.

9. The silicon nanoparticle according to claim 8, wherein the protein is an antigen, an antibody, a receptor or a ligand.

10. The silicon nanoparticles according to claim 1, wherein a pharmaceutically active compound is bound to the nanoparticle.

11. A pharmaceutical composition comprising silicon nanoparticles according to claim 1 and a pharmaceutically suitable carrier.

12. A method for synthesis of the silicon nanoparticles according to claim 1, said method comprising the steps of: mixing a surfactant and a solvent and sonification of the mixture for forming micelles, adding SiCl.sub.4 and sonification, adding a reducing agent for forming hydrogen-terminated silicon nanoparticles and sonification, adding an allylamine or poly(allylamine) comprising up to 10 allylamine groups in the presence of a catalyst and sonification, and extracting and purifying the resulting silicon nanoparticles, and mono- or multi-functionalising the silicon nanoparticles surface with a functional group selected from the group comprising a luminescent compound, a fluorescent compound, a light absorbing compound, a radioactive compound, a metal compound that can be visualized using x-rays, a compound that can be visualized using magnetic resonance imaging (MRI), a compound that can be visualized using ultrasound or microwave, a luminescent/fluorescent material that can be utilized in optical imaging, a X-ray contrast-giving agent that can be imaged by computed tomography (CT) or an isotope that can be imaged by positron emission tomography (PET) or single photon emission computed tomography (SPECT); and binding the silicon nanoparticle's surface to targeting molecules and/or therapeutically relevant molecules selected from the group comprising toxins, radionuclides and chemotherapeutics.

13. The method according to claim 12, wherein the sonification in each case is performed simultaneously or subsequently.

14. The method according to claim 12, wherein the surfactant is tetraoctylammonium bromide, the solvent is toluene, the reducing agent is LiAlH.sub.4 and the catalyst is H.sub.2PtCl.sub.6.

15. A method comprising the step of providing silicon nanoparticles of claim 1 for in vivo bioimaging.

16. A method comprising the step of providing a pharmaceutical composition according to claim 11 for in vivo bioimaging.

17. The method of claim 15, wherein in vivo bioimaging is used for in vivo diagnostics, visualization or staining of drug delivery, cells, biological processes or pathways.

18. A method comprising the step of providing silicon nanoparticles according to claim 1.

19. The method according to claim 18, wherein the chemotherapeutic agent comprises cisplatin, carboplatin, fluorouracil, methotrexate, paclitaxel, docetaxel or doxorubicin.

20. The method according to claim 18, wherein a radio-metal complex is used comprising therapeutically relevant radionuclides selected from the group of .sub.67Cu, .sub.90Y, .sub.131I, .sub.153SM, .sub.166Ho, .sub.177Lu, .sub.186Re or .sub.188Re.

21. A method comprising the step of providing silicon nanoparticles according to claim 1 for the combination of molecular in vivo imaging and targeted treatment of diseases.

22. A method comprising the step of providing silicon nanoparticles according to claim 1 in a combination of therapeutic methods selected from the group comprising hyperthermia, chemotherapy, radiation therapy and/or radionuclide therapy using targeted silicon nanoparticles.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The disclosure will be illustrated by figures without being limited to them. It shows:

(2) FIG. 1: 1A: Absorption spectrum of silicon nanoparticles. 1B: Emission spectra of silicon nanoparticles terminated with amino groups at different excitation wavelengths.

(3) FIG. 2: 2A: Lifetime spectrum of silicon nanoparticles. 2B: FTIR spectrum of silicon nanoparticles.

(4) FIG. 3: Absorption spectra of Kodak-XS-670-labeled silicon nanoparticles and Kodak-XS-670 (inset) in water.

(5) FIG. 4: In vivo fluorescence images of NMRI nu/nu mouse using Kodak-XS-670-labeled silicon nanoparticles (Kodak in vivo imaging system FX).

(6) FIG. 5: Ex vivo whole body freeze section (80 m) fluorescence images of NMRI nu/nu mice at 5 min (A), 60 min (B) and 24 h (C) after single intravenous injection of Kodak-XS-670-labeled silicon nanoparticles.

(7) FIG. 6: Delineation of ROI's (bladder, heart, intestine, tumour, muscle) on a representative 2D fluorescence image of a nude mice after 2 h of single intravenous injection of 200 L Kodak-XS-670-labeled silicon nanoparticles.

(8) FIG. 7: 2D near infrared (NIR) fluorescence (excitation 670 nm, emission 790 nm, measurement duration of each frame 5 min) images measured before injection (0 min) of Kodak-XS-670-labeled silicon nanoparticles and every 5 min up to 2 hours.

(9) FIG. 8: Kinetics of the in vivo fluorescence intensity in ROIs of a representative mouse after single intravenous injection of Kodak-XS-670-labeled silicon nanoparticles.

(10) FIG. 9: Tumour to muscle ratio time curve of the fluorescence intensity kinetics in a NMRI nu/nu tumour (FaDu) bearing mouse.

(11) FIG. 10: Representative maximum intensity projections of small-animal PET images (1, 5 and 60 minutes) of NMRI nu/nu mouse using .sup.64Cu-radiolabeled DMPTACN-containing silicon nanoparticles.

(12) FIG. 11: Accumulation kinetics of .sup.64Cu-labeled silicon nanoparticles (DMPTACN-containing silicon nanoparticles) (NAP 1mouse 1, NAP 2mouse 2) and .sup.64Cu-TETA (TETA 1mouse 3, TETA 2mouse 4) for comparison in the bladder of four mice.

DETAILED DESCRIPTION OF THE INVENTION

(13) Functionalization is the addition of functional groups onto the surface of a material by chemical synthesis methods. The functional group added can be subjected to ordinary synthesis methods to attach virtually any kind of compound onto the surface. Silicon nanoparticles can be functionalised with a luminescent compound, a fluorescent compound, a light absorbing compound, a radioactive compound, a metal compound that can be visualized using x-rays, a compound that can be visualized using magnetic resonance imaging (MRI), a compound that can be visualized using ultrasound or microwave, an isotope that can be imaged by x-ray computed tomography (CT) or positron emission tomography (PET) or single photon emission computed tomography (SPECT). Multimodal imaging is also possible with the same strategy. Functionalization of silicon nanoparticles with therapeutic agents, e.g. toxins, radionuclides and chemotherapeutics will allow therapeutic applications.

(14) Thus, particles can be functionalized with the relevant functional groups needed for a particular application, e.g. one group for targeting a special kind of tissue or cell and another groups as reporter group like a dye or a fluorescent compound or radiolabel or contrast-enhancing units.

(15) Bioimaging within the meaning of the present disclosure means non-invasive labelling of biological structures such as biological molecules, whole cells or subcellular structures, organ systems, tissues such as tumour tissue or whole organisms. Biological pathways and processes can also be visualized.

(16) Bioimaging is useful for but not limited to in vivo diagnostics, visualization of drug delivery and staining of cells, biological pathways and processes.

(17) In vivo diagnostics within the meaning of the present disclosure comprises imaging technologies with the aim of labelling specific biological structures such as biological molecules, whole cells or subcellular structures, organ systems or tissues such as tumour tissue for diagnosis of diseases or disorders at a cellular level. For that purpose, contrast agents, antibodies or nanoparticles are exemplary molecules that are administered before or during examination.

(18) Drug delivery comprises administering a pharmaceutical composition to achieve a therapeutic effect in humans or animals. Bioimaging can be useful in visualization of drug delivery in that pharmaceutical compositions are labeled as written above and administration is monitored via imaging technologies.

(19) Cell staining can be performed in the same way. Whole cells or subcellular structures can be labeled as written above and visualized via imaging technologies.

(20) Therapeutic treatment can be performed by combining the silicon nanoparticles modified with metal binding ligands with therapeutic radionuclides, toxins as well as chemotherapeutics, and administration in patients with tumours or other nanoparticles retaining foci of disease.

(21) Targeting molecules shall comprise molecules directing the nanoparticles to specific cells, cell structures or tissues as well as molecules, which target for instance a specific cellular pathway and thus block tumour growth or spreading for example.

SYNTHESIS AND CHARACTERIZATION

Synthesis

(22) Silicon nanoparticles were prepared using a modification of a method reported by Warner et al. 1.5 g of tetraoctylammonium bromide was mixed with 100 ml of dry toluene and mixture was sonicated for 30 min, in a N.sub.2 glove box. 100 l of SiCl.sub.4 was added via a gas-tight syringe and sonication was continued for 30 min allowing entrance in micelles. Subsequently, 2.3 mL of LiAlH.sub.4 (1 M in THF) was added in order to form hydrogen-terminated silicon nanoparticles. After 30 min of sonication, dry and deaerated methanol (30 ml) was added to react with the excess LiAlH.sub.4.

(23) Alkylamine terminated nanoparticles were obtained in the reactions of degassed allyl-amine (2.7 g), with hydrogen-terminated silicon nanoparticles, in the presence of 40 l of 0.05 M H.sub.2PtCl.sub.6 catalyst. After 30 min of sonication, 3-amino-propyl silicon nanoparticles were extracted with water, washed with ethyl-acetate and filtrated twice through syringe membrane filters (Millex, Millipore, PVDF, 0.45 m). The resulting silicon nanoparticles were further purified by dialysis against water (MWCO 7000, SERVA, Membra-Cel dialysis tubing, diameter 22 mm) to remove any residuals of unreacted amino-alkene and surfactant.

(24) Silicon Nanoparticle Characterization

(25) Characterization of these particles was done in collaboration with Dr. Manuel Tsotsalas. These include FTIR, NMR and HRTEM. In addition to this complete photophysical characterization was performed. These results are presented in FIG. 1 and FIG. 2.

(26) These results confirm the formation of silicon nanoparticles. The 1661 cm.sup.1 in the IR data can be attributed to the allylamine vibrations and it clearly indicates attachment to the Si surface. The peaks between 1000 and 1100 cm.sup.1 can be attributed to SiOR vibrations. These assignments are based on literature.

EXAMPLES

(27) The disclosure will be illustrated by the following examples without being limited to them. The examples shown involve in vivo experiments.

Example 1: Preparation and In Vivo Characterization of Fluorophore-Labeled Silicon Nanoparticles (Kodak-Xs-670-Labeled Nanoparticles)

(28) 36 L amino-terminated silicon nanoparticles (c=2 mg/mL) were added to 964 L phosphate buffer (Sorensen, 10 mM, pH=7.5). Then, 1 mg (0.88 mol) KODAK X-Sight-670 tetrafluorophenyl ester was added and the mixture was stirred for 3 hours at room temperature. Unreacted material was separated by dialysis (MWCO 7000, Serva, Membra-Cel) until the solvent becomes colorless (8 times with 300 mL H.sub.2O each in 8 hours cycles). 20 L of XS-670-containing silicon nanoparticles were added to 680 L H.sub.2O (c0.025 mg/mL) and an absorption spectrum was recorded. As can be seen from FIG. 3, XS-670-containing silicon nanoparticles have the same absorption spectra as the free dye. An aqueous solution (870 g XS-670-Si-nanoparticles/mL) was used for in vivo experiments. In a typical experiment, 200 L, of this solution was administered to a NMRI nu/nu mouse. In vivo fluorescence images of NMRI nu/nu mouse using Kodak-XS-670-labeled silicon nanoparticles were exposed with a Kodak in vivo imaging system FX after 5 minutes, 1 hour and 24 hours (FIG. 4). In parallel, ex vivo studies using frozen sections (80 m thickness) of NMRI nu/nu mouse were performed with mice sacrificed after 5 min, 1 h or 24 h. The images (FIG. 5) show that the Kodak-XS-670-labeled nanoparticles were fast eliminated through the kidneys into the bladder. The particles were transiently observed in body regions with lymphatic system. However, after 24 hours no fluorescence originating from the particles were detected in the body, exclusively in traces in the bladder.

(29) A more detailed dynamic study of the fast distribution of the Kodak-XS-670-labeled nanoparticles in tumour bearing (FaDu) NMRI nu/nu mouse was carried out after single intravenous injection of 200 L Kodak-XS-670-labeled nanoparticles. The 2D near infrared (NIR) fluorescence (excitation 670 nm, emission 790 nm, measurement duration of each frame 5 min) was measured before injection (0 min) and every 5 min up to 2 hours in the inhalation anesthetized (9% desflurane, 30% oxygen) mouse (body temperature 37 C.). The fluorescence intensity of different regions representing heart, tumour, muscle, intestine and bladder in the images (see FIG. 6) was measured by the ROVER software (ABX GmbH, Radeberg, Germany). Masks for defining two-dimensional regions of interest (ROI) were set and the ROI's were defined by threshold and ROI time activity curves (TAC) were derived for the subsequent data analysis. The fluorescence intensity (units/cm.sup.2) and the normalized to the maximum value data were used for further analysis. The multiple frames (FIG. 7) show the fast accumulation of the nanoparticles in the bladder and the decreasing intensity in the thorax region. The fluorescence intensity after 2 h was highest in the bladder, followed by intestine, tumour, heart, and muscle. The kinetic analysis of the time-fluorescence curves (FIG. 8) showed clearance in all measured regions with half-lives of 24 min (thorax-heart), 22 min (muscle), 25 min (tumour). These fluorescence signals of the nanoparticle kinetics in the body are in good agreement with the quantitative measurements using small-animal PET (half life of .sup.64Cu-labeled nanoparticles was in the muscle 18 min) if the measured regions are located near to the surface (skin). The similar values of the measured half-lives in the fluorescence measurements could be explained by the dominant effect of the Kodak-XS-670-labeled nanoparticles in the blood. It is noteworthy that the relation of the fluorescence intensity tumour to muscle shows a continuously increase over the time (FIG. 9).

Example 2: Preparation and In Vivo Characterization of 64Cu-Labeled Silicon Nanoparticles (DMPTACN-Containing Silicon Nanoparticles)

(30) 0.7 mg (1.4 mol) 2-[4,7-Bis(pyridylmethyl)-1,4,7-triazacyclononan-1-yl]-N-(4-isothiocyanatophenyl)-acetamide (DMPTACN-Ph-NCS) as bifunctional chelating agent in 200 L water was added to 0.5 mL amino-terminated silicon nanoparticles (c=2 mg/mL) dissolved in NaHCO.sub.3 buffer (10 mM, pH=8.3). The mixture was stirred for 24 hours at room temperature. Purification of the DMPTACN-Ph-thiourea-containing silicon nanoparticles was performed using dialysis (MWCO 7000, SERVA, Membra-Cel). The dialysate was concentrated under reduced pressure. The residual was dissolved in 100 L water/acetonitrile (1/1) and analyzed by HPLC. Dialysis was repeated five times with 500 mL H.sub.2O each in 8 hours cycles. After that, DMPTACN-Ph-NCS was not detected by HPLC (Jupiter proteo 4 m C12 90 (Phenomenex), 2504.6 mm; eluent A (acetonitrile containing 0.1% trifluoroacetic acid), eluent B (water containing 0.1% trifluoroacetic acid, elution gradient 10% A to 100% in 60 minutes, 1 mL/min, t.sub.R (DMPTACN-Ph-NCS)=20.6 min) The retentate was then concentrated under reduced pressure. DMPTACN-Ph-thiourea-containing silicon nanoparticles (100 g in 160 L) were dissolved in 2-[N-morpholino]ethanesulfonic acid (MES)-NaOH buffer (0.02 M, pH=6.2, c=625 g nanoparticles/mL). For biodistribution and small animal PET experiments, 100 g DMPTACN-Ph-thiourea-containing silicon nanoparticles dissolved in 250 L MES-NaOH buffer were radiolabeled with [.sup.64Cu]CuCl.sub.2 (40 MBq in 0.01 HCl) at room temperature for 30 minutes. To remove the non-specific bound radioactivity, 10 L aqueous solution of 10 mM TETA (1,4,8,11-tetraazacyclotetradecane-1,4,811-tetraacetic acid) was added to the radiolabeled silicon nanoparticles and incubated for 10 minutes at room temperature. Purification of .sup.64Cu-labeled silicon nanoparticles was performed by HPLC (Jupiter proteo 4 m C12 90 (Phenomenex), 2504.6 mm; eluent A (acetonitrile containing 0.1% trifluoroacetic acid), eluent B (water containing 0.1% trifluoroacetic acid, elution gradient 10% A to 100% in 30 minutes, 1 mL/min, t.sub.R (64Cu-TETA)=4.1 min, t.sub.R (64Cu-DMPTACN-sihcon nanoparticles)=12.3 min) Solvents used for HPLC were evaporated in vacuo, and after that the .sup.64Cu-labeled silicon nanoparticles were dissolved in isotonic sodium chloride solution.

(31) 20 MBq of .sup.64Cu-silicon nanoparticles in 0.5 mL isotonic NaCl solution was administered intravenously over one minute into the tail vein of a NMRI nu/nu mouse. The mice (body weight 403 g) were anesthetized through inhalation of Desflurane (10% Suprane) in 30% oxygen/air (gas flow, 1 L/min) Mice were positioned and immobilized prone with their medial axis parallel to the axial axis of the scanner (microPET P4, Siemens preclinical solutions, Knoxville, Tenn., USA). For attenuation correction, a 10 min transmission scan was obtained using a rotating .sup.57Co point source before tracer injection and collection of the emission scans. The radioactivity of the injection solution in 1 mL syringe was measured in the well counter cross-calibrated with the scanner. The emission scan of 120-min PET acquisition was started and with a delay of 30 s the infusion of the radiotracer was initiated. A solution of 0.5 mL isotonic solution of about 1 MBq/animal was infused over 1 min with a Harvard Apparatus 44 syringe pump (Harvard Apparatus, Holliston, Mass., USA) using a needle catheter into a tail vein. Data acquisition was performed in 3D list mode. Emission data were collected continuously. The list mode data were sorted into sinograms with 32 frames (1510 s, 530 s, 560 s, 4300 s, 3600 s). The data were decay, scatter and attenuation corrected. The frames were reconstructed by Ordered Subset Expectation Maximization applied to 3D sinograms (OSEM3D) with 14 subsets, 15 OSEM3D iterations, 25 maximum a posteriori (MAP) iterations, and 1.8 mm resolution using the FastMAP algorithm (Siemens Preclinical Solutions, Knoxville, Tenn.). The pixel size was 0.07 by 0.07 by 0.12 cm, and the resolution in the center of field of view was 1.8 mm. No correction for partial volume and recovery effects was applied. The image volume data were converted to Siemens ECAT7 format for further processing. The image files were then processed using the ROVER software (ABX GmbH, Radeberg, Germany). Masks for defining three-dimensional regions of interest (ROI) were set and the ROI's were defined by thresholding and ROI time activity curves (TAC) were derived for the subsequent data analysis. The ROI data and TAC were further analyzed using R (R is available as Free Software under the terms of the Free Software Foundation's GNU General Public License in source code form) and especially developed program packages (Jrg van den Hoff, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany). The standardized uptake values (SUV.sub.PET, SUV.sub.PET=(activity/mL tissue)/(injected activity/body weight), mL/g; g/mL) and the fraction of injected activity were calculated in the ROIs. FIG. 10 shows the distribution of the .sup.64Cu-DMPTACN-silicon nanoparticles at 1, 5, and 60 min after injection. The particles were fast distributed and eliminated from the blood by the kidneys. After one hour the main activity amounts are in the bladder (quantitative data shown in FIG. 11) and the kidneys. Altogether, biodistribution and pharmacokinetics of .sup.64Cu-DMPTACN-silicon nanoparticles are very similar to the .sup.64Cu-labeled hydrophilic chelator TETA (1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid).

Example 3: Preparation and In Vivo Characterization of 64Cu-Labeled Silicon Nanoparticles NOTA-Containing Silicon Nanoparticles)

(32) 1 mg (1.8 mol) S-2-(4-Isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (SCN-Bn-NOTA) as bifunctional chelating agent was added to 0.5 mL amino-terminated silicon nanoparticles (c=2 mg/mL) dissolved in a borate buffer (0.1 M, pH=9.2). The mixture was stirred for 24 hours at room temperature. Purification of the NOTA-containing silicon nanoparticles was performed using dialysis (Pierce Slide A-Lyzer Cassette (MWCO=7000 g/mol), 2PBS 400 mL, 1H.sub.2O 400 mL). The dialysate was concentrated under reduced pressure. The residual was dissolved in 100 L, water/acetonitrile (1/1) and analyzed by HPLC. After purification by ultracentrifugation, SCN-Bn-NOTA was not detected by HPLC (ZORBAX 300 Extend-C18 5 m, 4.6250 mm; eluent A (H.sub.2O containing 0.1% trifluoroacetic acid), eluent B (acetonitrile containing 0.1% trifluoroacetic acid, elution gradient 90% A to 10% in 20 minutes, 1 mL/min, t.sub.R (SCN-Bn-NOTA)=13.697 min) The retentate was concentrated under reduced pressure. NOTA-thiourea-containing silicon nanoparticles were dissolved in 2-[N-morpholino]ethanesulfonic acid (MES)-NaOH buffer (0.05 M, pH=5.5, c=400 g nanoparticles/mL). For biodistribution and small animal PET experiments, 100 g DMPTACN-Ph-thiourea-containing silicon nanoparticles dissolved in 250 L, MES-NaOH buffer were radiolabeled with [.sup.64Cu]CuCl.sub.2 (40 MBq in 0.01 HCl) at room temperature for 30 minutes. At the end of the reaction, 10 L, aqueous solution of 10 mM TETA (1,4,8,11-tetraazacyclotetradecane-1,4,811-tetraacetic acid) was added to the radiolabeled silicon nanoparticles and incubate for 10 minutes at room temperature to remove the non-specific bound radioactivity. (ZORBAX 300 Extend-C18 5 m, 4.6250 mm; eluent A (H.sub.2O containing 0.1% trifluoroacetic acid), eluent B (acetonitrile containing 0.1% trifluoroacetic acid, elution gradient 90% A to 10% in 20 minutes, 1 mL/min, t.sub.R (.sup.64Cu-NOTA-silicon nanoparticles)=11.72 min). Solvents used for HPLC were evaporated in vacuo, and the .sup.64Cu-labeled silicon nanoparticles were dissolved in isotonic sodium chloride solution. 20 MBq of .sup.64Cu-NOTA-silicon nanoparticles in 0.5 mL isotonic NaCl solution was administered intravenously over one min into a tail vein of a NMRI nu/nu mouse. Biodistribution and pharmacokinetics of .sup.64Cu-NOTA-silicon nanoparticles are comparable to those of .sup.64Cu-DMPTACN-silicon nanoparticles.

Example 4: Preparation and In Vivo Characterization of 90Y-Labeled Silicon Nanoparticles (DOTA-Containing Silicon Nanoparticles)

(33) 40 L (291 g, 0.4 mol) (S)-2-(4-Aminobenzyl)-1,4,7,10-tetraazacyclododecane-N,N,N,N-tetraacetic acid (NH.sub.2-Bn-DOTA) was dissolved in 1 mL 0.5 M NH.sub.4OAc buffer (pH=6.8). Then, 30 L [.sup.90Y]YCl.sub.3 (120 MBq) in 0.04 HCl was added, and the solution was stirred for 20 min at 95 C. in a thermo-mixer (1000 rpm). Purification of .sup.90Y-labeled NH.sub.2-Bn-DOTA was performed by means of SepPak Plus C.sub.18 cartridge (Waters, USA). After separation of unbound .sup.90Y.sup.3+ with 10 mL of NH.sub.4OAc buffer (pH=6.5, 0.05 M), [.sup.90Y]YNH.sub.2-Bn-DOTA was selectively eluted with 1.5 mL acetonitrile/water (80/20 v/v). The solution was evaporated to dryness under a nitrogen stream. The residue was dissolved in 100 L MES-NaOH buffer, and the purity of was checked by Radio-HPLC (Phenomenex Aqua-C18, 5 m, 4.6250 mm; eluent: 50 mM NH.sub.4OAc in water/acetonitrile=95/5, isocratic elution, 1 mL/min, (.sup.90Y.sup.III, t.sub.R=3.8 min; [.sup.90Y]YNH.sub.2-Bn-DOTA-isomer 1, t.sub.R=9.1 min; [.sup.90Y]YNH.sub.2-Bn-DOTA-isomer 2, t.sub.R=11.9 min; isomers according to Schlesinger et al.: Bioconjugate Chem. 2008; 19:928-39) and Radio-TLC (50 mM NH.sub.4OAc in water/acetonitrile=90/10 on silica plates ([.sup.90Y]YCl.sub.3, R.sub.f=0; [.sup.90Y]YNH.sub.2-Bn-DOTA, R.sub.f=0.7). A radiochemical yield higher than 99% was determined using Radio-HPLC.

(34) To 100 g carboxylic acid-terminated silicon nanoparticles dissolved in 150 L MES-NaOH buffer (pH=5.5), 1 mg 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) was added and the mixture was incubated in a thermo mixer for ten minutes at room temperature. To this solution, 100 MBq [.sup.90Y]YNH.sub.2-Bn-DOTA was added and the mixture was stirred for three hours at room temperature. Purification of the .sup.90Y-labeled DOTA-containing silicon nanoparticles was performed using dialysis (Pierce Slide A-Lyzer Cassette (MWCO=7000 g/mol), 2PBS 400 mL, 1H.sub.2O 400 mL). The dialysate was concentrated under reduced pressure. The residual was dissolved in 100 L MES-NaOH buffer and analyzed by HPLC. After purification by ultracentrifugation, no free [.sup.90Y]YNH.sub.2-Bn-DOTA was detected by Radio-HPLC. Solvents were evaporated using a nitrogen stream, and the .sup.90Y-labeled silicon nanoparticles were dissolved in isotonic sodium chloride solution. In vivo investigations were performed with .sup.90Y-labeled silicon nanoparticles dissolved in in isotonic sodium chloride solution with a specific activity of 10 to 200 MBq/g silicon nanoparticles.

(35) Animal cohorts: Tumorigenic human cancer cells like human squamous cell carcinoma cells or prostate carcinoma cells were implanted subcutaneously into the leg or neck regions or human brain carcinoma cells by using stereotactic procedures into the brains of a number of athymic nude mice and allowed to develop into a tumor for 8 to 24 days. Mice with tumors ranging from 6 to 12 mm in diameter (approximately 1 cm.sup.3 in volume) were selected for the studies. .sup.90Y-labeled DOTA-containing silicon nanoparticles (0.5 to 5 MBq) in approximately 0.2 ml were applied in the studies.

(36) Biodistribution: Biodistribution studies with .sup.90Y-labeled DOTA-containing silicon nanoparticles were performed in mice at various time points over 3 weeks using SPECT, section or autoradiography to evaluate .sup.90Y-content. Radionuclide imaging was performed using small animal SPECT/CT at each time point immediately followed by euthanasia.

(37) For anatomical localization of SPECT images, X-ray CT data were acquired; volumetric CT images were reconstructed provided by an algorithm the manufacturer. Following euthanasia, major organs including heart, lungs, brain, liver, pancreas, kidneys, small intestine, and intestine were isolated, the tumor was resected, and samples of bone (femur), skin, and muscle were dissected. These samples were weighed and counted with appropriate standards using a calibrated gamma scintillation counter or the samples were dissolved in tissue solubilzer and bleached with hydrogen peroxide and perchlorate followed by addition of scintillator and counted in scintillation counter to determine the localization of the specific radiolabeled nanoparticles in each organ. The results of scintillation counting were expressed as percentage of the injected dose per gram of tissue (% ID/g) or SUV (g/mL) and were corrected for physical radionuclide decay. To determine differences in the biodistribution of the .sup.90Y-nanoparticles, statistical analysis (Student's t test) was performed using SPSS 11 software package (SPSS, Chicago, Ill., USA).

(38) Autoradiography: Tumor tissue samples were immediately frozen at 60 C. and embedded in tissue medium. Tissue samples were cryosectioned at 20-m thicknesses. Sections were mounted on glass coverslips, placed on cardboard, and exposed on a storage phosphor image plate for 1 to 12 h. The plate then was scanned with an imaging system.

(39) Survival studies: Survival studies involved minimal three cohorts mice that received .sup.90Y-DOTA or the non-labeled nanoparticles or the radiolabeled .sup.90Y-labeled DOTA-containing silicon nanoparticles by intravenous infusion or intraperitoneal injection or by means of convection enhanced delivery into the brains at one to three weeks after tumor implantation. Mice in survival studies were divided into three groups: one comprised untreated mice that received the non-labeled nanoparticles, the .sup.90Y-DOTA and the other comprised mice treated with the .sup.90Y-labeled DOTA-containing silicon nanoparticles that received between 20 and 60 MBq of .sup.90Y-labeled DOTA-containing silicon nanoparticles. Survival data were evaluated by using Kaplan-Meier statistical methods.

Example 5: Preparation and In Vivo Characterization of 177Lu-Labeled Silicon Nanoparticles (DOTA-Containing Silicon Nanoparticles)

(40) .sup.177Lu-labeled silicon nanoparticles have been obtained using the same procedure applied for the .sup.90Y-labeling described in example 4. In vivo investigations were performed with .sup.177Lu-labeled silicon nanoparticles dissolved in in isotonic sodium chloride solution with a specific activity of 10 to 200 MBq/g silicon nanoparticles.

(41) Animal cohorts: Tumorigenic human cancer cells like human squamous cell carcinoma cells or prostate carcinoma cells were implanted subcutaneously into the leg or neck regions or human brain carcinoma cells by using stereotactic procedures into the brains of a number of athymic nude mice and allowed to develop into a tumor for 8 to 24 days. Mice with tumors ranging from 6 to 12 mm in diameter (approximately 1 cm3 in volume) were selected for the studies. .sup.177Lu (4020 MBq) in approximately 0.2 ml were applied in the studies.

(42) Biodistribution: Biodistribution studies with .sup.177Lu-labeled particles were performed in mice at various time points over 3 weeks using SPECT, section or autoradiography to evaluate 177Lu-content. Radionuclide imaging was performed using small animal SPECT/CT at each time point immediately followed by euthanasia.

(43) For anatomical localization of SPECT images, X-ray CT data were acquired; volumetric CT images were reconstructed provided by an algorithm the manufacturer. Following euthanasia, major organs including heart, lungs, brain, liver, pancreas, kidneys, small intestine, and intestine were isolated, the tumor was resected, and samples of bone (femur), skin, and muscle were dissected. These samples were weighed and counted with appropriate standards using a calibrated gamma scintillation counter to determine the localization of the specific radiolabeled nanoparticles in each organ. The results of scintillation counting were expressed as percentage of the injected dose per gram of tissue (% ID/g) or SUV (g/mL) and were corrected for physical radionuclide decay. To determine differences in the biodistributions of the .sup.177Lu-nanoparticles statistical analysis (Student's t test) was performed using SPSS 11 software package (SPSS, Chicago, Ill., USA).

(44) Autoradiography: Tumor tissue samples were immediately frozen at 60 C. and embedded in tissue medium. Tissue samples were cryosectioned at 20-m thicknesses. Sections were mounted on glass coverslips, placed on cardboard, and exposed on a storage phosphor image plate for 1 to 12 h. The plate then was scanned with an imaging system.

(45) Survival studies: Survival studies involved minimal three cohorts mice that received .sup.177Lu-DOTA or the non-labeled nanoparticles or the radiolabeled .sup.177Lu-nanoparticles by intravenous infusion or intraperitoneal injection or by means of convection enhanced delivery into the brains at one to three weeks after tumor implantation. Mice in survival studies were divided into three groups: one comprised untreated mice that received the non-labeled nanoparticles, the .sup.177Lu-complex and the other comprised mice treated with the .sup.177Lu-labeled nanoparticles that received between 20 and 60 MBq of .sup.177Lu-nanoparticles. Survival data were evaluated by using Kaplan-Meier statistical methods.

Example 6: Preparation of Peptide-Conjugated Silicon Nanoparticles and Targeting to Epidermal-Growth-Factor-Receptor (EGFR)

(46) To 0.5 mg amino-terminated silicon nanoparticles, dissolved 100 L, PBS buffer, 137 g (11 mol) 2-iminothiolane hydrochloride was added, and the mixture was stirred for 12 hours at room temperature. A maleimido-functionalized peptide conjugate was obtained by treatment of 0.5 mol gly-gly-gly-leu-ala-arg-leu-leu-thr with 0.55 mol 3-(maleimido) propionic acid N-succinimidyl ester in 100 L, PBS buffer for 12 hours at room temperature. A maleimido-functionalized dye molecule was prepared by reaction of 0.15 mol 8-(3-Aminopropyl)-4,4-difluoro-1,3,5,7-tetramethyl-4-bora3a,4a-s-indacene (BODIPY-NH.sub.2) with 0.15 mol 3-(maleimido) propionic acid N-succinimidyl ester in 500 L, PBS buffer for 12 hours at room temperature. The three reaction products (sulfydryl-terminated silicon nanoparticles, maleimido-functionalized peptide and dye conjugate) were mixed together and stirred 15 hours at room temperature. The reaction product was filtered three times using a membrane filter (Amicon Ultra0.5 ml 3 K, Amicon Ultra centrifugal filters, MILLIPORE) with PBS buffer at 6000 rpm. For saturation of the remaining sulfhydryl groups, the purified silicon nanoparticles were re-suspended in 100 L, PBS buffer, and 7 mol of 25-maleinimido-23-oxo-4,7,10,13,16,19-hexaoxa-22-azapentacosanoic acid succinimidyl ester was added. The reaction mixture was stirred for 8 hours at room temperature. The pegylated particles were purified three times using a membrane filter (Amicon Ultra0.5 ml 3 K, Amicon Ultra centrifugal filters, MILLIPORE) with deionized water at 6000 rpm.

(47) Targeting to Epidermal-Growth-Factor-Receptor (EGFR) of the pegylated silicon nanoparticles containing peptide residues (5% gly-gly-gly-leu-ala-arg-leu-leu-thr) and the fluorescent tag BODIPY (1%) was proven by an immunological binding assay. A human epithelial carcinoma cell line (A431) growing under appropriate conditions was harvested and lysed by mechanical disruption in phosphate-buffered-saline (PBS) including 0.05% Chremophor. This detergent was suitable for solubilisation of membrane proteins, which were obtained in the supernatant after centrifugation of the lysed cells. Protein content was determined by Bradford's method (Bradford, Anal. Biochem. 1976, 72, 248-254). Different concentrations of pegylated silicon nanoparticles with gly-gly-gly-leu-ala-arg-leu-leu-thr) and BODIPY were added to definitive protein concentrations of the supernatant in PBS buffer and allowed to react for 30 minutes at 37 C. The reaction was stopped by addition of Laemmli sample buffer and proteins were separated subsequently by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) (Laemmli, Nature 1970, 227, 680-685). Proteins were transferred from the gel onto nitrocellulose membrane by semi-dry electro-blotting at 4 C. overnight. Fluorescent protein bands on the membrane were detected by an imaging system using excitation/emission wavelengths of 488/520 nm. After blocking, the membrane was incubated with an anti-EGFR antibody and subsequently with a secondary, horseradish-peroxidase labeled antibody. EGFR bands were detected using the peroxidase reaction producing chemiluminescence. The exact alignment of the fluorescence (BODIPY) and chemiluminescence in one protein band suggest a stable bound between the silicon nanoparticle-peptide conjugate and EGFR even under reducing conditions during a SDS gel electrophoresis.