FABRICATION OF BLUE-FLUORESCENT AND NON-TOXIC NANODIAMONDS 9NDs) FROM ATMOSPHERIC PARTICULATE MATTERS

Abstract

The present invention relates to a method for fabrication of blue-fluorescent and non-toxic nanodiamonds from atmospheric particulate matters including total solid suspended particulate matter (TSPM) and particulate matter with size less than 10μ (PM.sub.10). Mostly, the present invention provides an efficient mitigation process for particulate pollutant by conversion of these pollutants (PM and TSPM) into non-toxic high-value product such as nanodiamond by using the ultrasonic-assisted chemical oxidation method. This method is environmental friendly, simple, and biocompatible for the production of nanodiamonds from such atmospheric particulate matter.

Claims

1. A method for preparing nanodiamonds from atmospheric pollutants comprising the steps of: a) collecting atmospheric pollutants; b) mixing the atmospheric pollutants obtained in step (a) with hydrogen peroxide to obtain an oxidized particulate matter; c) ultrasonicating the oxidized particulate matter obtained in step (b) to obtain a first mixture; d) filtering the first mixture obtained in step (c) using a polytetrafluoroethylene membrane filter (0.22 μm) to obtain a filtrate; e) centrifuging the filtrate obtained in step (d) to obtain a supernant; f) treating the supernatant obtained in step (e) with HNO.sub.3/H.sub.2SO.sub.4 acid and heating to obtain an extract; g) neutralizing the extract obtained in step (f) by adding ammonia solution drop wise to obtain a second mixture; h) filtering the second mixture obtained in step (g) using an ultrafiltration (1 KDa) to obtain a filtrate solution; and i) concentrating the filtrate solution obtained in step (h) to obtain the nanodiamonds.

2. The method as claimed in claim 1, wherein the atmospheric pollutants comprise Total Suspended Particulate Matter having the particle size less than 100 μm (TSPM) and Particulate Matter having the size of aerodynamic diameter of 2.5-10 μm (PM.sub.10).

3. The method as claimed in claim 1, wherein the atmospheric pollutants are collected using High Volume Sampler or Respirable Dust Sampler on quartz filter papers.

4. The method as claimed in claim 1, wherein the hydrogen peroxide used in step (b) is 30% (v/v).

5. The method as claimed in claim 1, wherein the ultrasonication in step (c) is carried out for 1 hour at room temperature.

6. The method as claimed in claim 1, wherein the centrifugation in step (e) is carried out at 1400 rpm for 1 hour.

7. The method as claimed in claim 1, wherein heating in step (f) is carried out at 55-60° C. for 30 min.

8. A nanodiamond having a diameter in the range of 3-24 nm and a X-ray diffraction pattern showing peaks at the d-spacings listed in Table A: TABLE-US-00005 TABLE A ‘d’ spacing value (Å) 2θ (°) 2.0 43.22 1.26 75.1

9. The nanodiamond as claimed in claim 8 having oxygen-containing hydrophilic functional groups and blue-fluorescence under UV-light.

10. The nanodiamond as claimed in claim 8, wherein said nanodiamond are non-toxic and bio-compatible.

11. The nanodiamond as claimed in claim 8 for use in bio-sensing, biomedical imaging, drug delivery, wear resistant polymer, lubricant additives, and metal coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1: Schematic diagram of Environmental sampler used for the collection of atmospheric particulate matter. FIG. 1a shows the High volume sampler containing 1. Flow meter, 2. Valve, 3. timer, 4. Pump, 5. Outlet, 6. Filter paper containing TSPM. FIG. 1b shows the Respirable Dust Sampler containing 1. Air Inlet, 2. Flow meter, 3. Cyclone assembly, 4. Dust sample deposited chamber, 5. Suction device 6. Timer, 7. Pump, 8. Filters containing PM.sub.10.

[0038] FIG. 2 represent the process for the preparation of Nanodiamonds (NDs) from atmospheric pollutants (PM.sub.10 and TSPM) in accordance with the invention.

[0039] FIG. 3 Flow sheet provides a technique of nanodiamond fabrication in large scale quantity for commercial use. The steps comprise: 1. Collection of air pollutants using Air sampler. 2. Mixing tank with ultrasonicator. 3. Filtration unit. 4. Centrifuge. 5. Mixing tank. 6. Ultra-filtration. 7. Rotary Evaporator.

[0040] FIG. 4 Provides the Transmission Electron Micrograph of nanodiamond (NDs) prepared from TSPM according to the present invention. FIG. 4a shows the nanodiamonds prepared from TSPM. FIG. 4b shows the elements (C and O) present in fabricated product. FIG. 4c shows Fast Fourier Transform (FFT) Pattern and, FIG. 4d shows the size distribution of NDs derived from TSPM.

[0041] FIG. 5 Provides the High resolution Transmission Electron Micrograph of the NDs prepared from TSPM according to the present invention. FIGS. 5a and b show the HRTEM images of nanocrystal as highlighted by hexagon. FIGS. 5c and d shows FFT pattern showing the hexagonal crystalline structure of the carbon particle. FIGS. 5e and f show the Elemental mapping images indicate presence of C and O element.

[0042] FIG. 6 Provides data relating to characterizations techniques like XRD (FIG. 6a), FTIR (FIG. 6b), and Raman (FIG. 6c) of the NDs prepared from TSPM.

[0043] FIG. 7 Provides the data relating to optical properties of NDs prepared from TSPM. FIG. 7a shows UV-visible spectra of NDs prepared from TSPM. FIG. 7b shows FL spectra of NDs prepared from TSPM. FIG. 7c-i shows the NDs in day light and 7c-ii shows the ND sample under UV light at 365 nm.

[0044] FIG. 8 Provides the Transmission Electron Micrograph of the NDs prepared from PM.sub.10 according to the present invention. FIG. 8a shows the nanodiamonds prepared from PM.sub.10. FIG. 8b shows the elements (C and O) present in fabricated product. FIG. 8c shows Fast Fourier Transform (FFT) Pattern and, FIG. 8d shows the size distribution of ND obtained from PM.sub.10.

[0045] FIG. 9 Provides the High resolution Transmission Electron Micrograph of the ND prepared from PM.sub.10 according to the present invention. FIGS. 9a and b shows the HRTEM images of carbon nanocrystal. FIGS. 9c and d shows FFT pattern showing the hexagonal crystalline structure of the carbon particle.

[0046] FIG. 10 provides data relating to the other characterizations techniques like XRD (FIG. 10a), FTIR (FIG. 10b), and Raman (FIG. 10c) of the NDs prepared from PM.sub.10.

[0047] FIG. 11 Provides the data relating to optical properties of NDs prepared from PM.sub.10. FIG. 11a shows UV-visible spectra of ND prepared from PM.sub.10. FIG. 11b shows FL spectra of ND prepared from PM.sub.10. FIG. 11c-i shows the ND in day light and 11c-ii shows the ND under UV light at 365 nm.

[0048] FIGS. 12A-12B provide the zeta potential analysis data of NDs prepared from TSPM (Figure a) and PM.sub.10 (Figure b) for the determination of surface properties.

[0049] FIGS. 13A-13B provide the data relating to toxicity of NDs at cellular and genetic level derived from both TSPM (NDs coded as S1) and PM.sub.10 (NDs coded as S2).

DETAILED DESCRIPTION OF THE INVENTION

[0050] The present invention relates to a method for preparation of blue-fluorescent and nontoxic nanodiamonds from atmospheric pollutants (SPM and PM.sub.10) with the help of ultrasonic-assisted chemical oxidation method.

[0051] The present invention is related to use of air pollutants as a source of carbon and conversion of same into value added carbon nanomaterials such as nanodiamonds (NDs). The carbon source is mostly vehicular exhaust diesel particulate matter. The method comprises chemical oxidation with the help of Hydrogen peroxide (30%) which is considered as environment friendly. The formed nanodiamond products are functionalized with a hydroxyl groups, carbonyl group, carboxyl group etc. Therefore, it shows fluorescence properties and the product is non-toxic and biocompatible.

[0052] The present invention provides a method for preparing nanodiamonds from atmospheric pollutants comprising the steps of: [0053] a) collecting atmospheric pollutants; [0054] b) mixing the atmospheric pollutants obtained in step (a) with hydrogen peroxide to obtain an oxidized particulate matter; [0055] c) ultrasonicating the oxidized particulate matter obtained in step (b) to obtain a first mixture; [0056] d) filtering the first mixture obtained in step (c) using a polytetrafluoroethylene membrane filter (0.22 μm) to obtain a filtrate; [0057] e) centrifuging the filtrate obtained in step (d) to obtain a supernant; [0058] f) treating the supernatant obtained in step (e) with HNO.sub.3/H.sub.2SO.sub.4 acid and heating to obtain an extract; [0059] g) neutralizing the extract obtained in step (f) by adding ammonia solution drop wise to obtain a second mixture; [0060] h) filtering the second mixture obtained in step (g) using an ultrafiltration (1 KDa) to obtain a filtrate solution; and [0061] i) concentrating the filtrate solution obtained in step (h) to obtain the nanodiamonds.

[0062] In an embodiment of the present invention, there is provided a method for preparing nanodiamonds from atmospheric pollutants, wherein the atmospheric pollutants comprise Total Suspended Particulate Matter having the particle size less than 100 μm (TSPM) and Particulate Matter having the size of aerodynamic diameter of 2.5-10 μm (PM.sub.10).

[0063] In another embodiment of the present invention, there is provided a method for preparing nanodiamonds from atmospheric pollutants, wherein the atmospheric pollutants are collected using High Volume Sampler or Respirable Dust Sampler on quartz filter papers.

[0064] In yet another embodiment of the present invention, there is provided a method for preparing nanodiamonds from atmospheric pollutants, wherein the hydrogen peroxide used in step (b) is 30%.

[0065] In still another embodiment of the present invention, there is provided a method for preparing nanodiamonds from atmospheric pollutants, wherein the ultrasonication in step (c) is carried out for 1 hour at room temperature.

[0066] In an embodiment of the present invention, there is provided a method for preparing nanodiamonds from atmospheric pollutants, wherein the centrifugation in step (e) is carried out at 1400 rpm for 1 hour.

[0067] In another embodiment of the present invention, there is provided a method for preparing nanodiamonds from atmospheric pollutants, wherein heating in step (f) is carried out at 55-60° C. for 30 minutes.

[0068] An embodiment of the present invention provides nanodiamond prepared by the method of the present invention.

[0069] In another embodiment of the present invention, there is provided nanodiamond having a diameter in the range of 3-24 nm and a X-ray diffraction pattern showing peaks at the d-spacings listed in Table A:

TABLE-US-00002 TABLE A ‘d’ spacing value (Å) 2θ (°) 2.0 43.22 1.26 75.1

[0070] In yet another embodiment of the present invention, there is provided nanodiamond having a diameter in the range of 3-6 nm and a X-ray diffraction pattern showing peaks at the d-spacings listed in Table A:

TABLE-US-00003 TABLE A ‘d’ spacing value (Å) 2θ (°) 2.0 43.22 1.26 75.1

[0071] In still another embodiment of the present invention, there is provided nanodiamond having a diameter in the range of 10-24 nm and a X-ray diffraction pattern showing peaks at the d-spacings listed in Table A:

TABLE-US-00004 TABLE A ‘d’ spacing value (Å) 2θ (°) 2.0 43.22 1.26 75.1

[0072] In another embodiment of the present invention, there is provided nanodiamond having oxygen-containing hydrophilic functional groups and blue-fluorescence under UV-light.

[0073] In yet another embodiment of the present invention, there is provided nanodiamond, wherein said nanodiamond are non-toxic and bio-compatible.

[0074] Another embodiment of the present invention provides a nanodiamond for use in bio-sensing, biomedical imaging, drug delivery, wear resistant polymer, lubricant additives, and metal coating.

[0075] The present invention provides a method of producing nanodiamonds from a carbon source, such as atmospheric air pollutant (TSPM and PM.sub.10). These air pollutants are collected by using environmental samplers like Respirable Dust Sampler for PM.sub.10 and High volume sampler for Total Suspended Particulate Matter (TSPM) which are illustrated in FIG. 1.

[0076] The method of the present application is a feasible technique to remove associated atmospheric contaminants from particulate matter and convert them into nanodiamonds using chemical oxidation (H.sub.2O.sub.2 as an oxidizing agent) followed by ultrasonication process. This method requires less time and helps to separate carbon particles from impurities of Particulate Matters. The derived nanodiamond are confirmed by using different characterization techniques such as High resolution-transmission electron microscopy (HR-TEM; JEOL JEM 2100), X-ray diffraction (XRD; Rigako, Ultima IV), Raman spectroscopy (Horiba Jobin Vyon, Model LabRam HR), Fourier transforms infrared spectroscopy (FT-IR; System-2000, Perkin-Elmer), X-ray Photoelectron Spectrometer (XPS; ESCALAB Xi+), ultraviolet-visible spectroscopy (UV-visible; Analytik Jena, SPECORD200, Germany), fluorescence spectroscopy (FL; Horiba Fluorlolog-3), and Zeta potential (ZETASIZER; Model-Nano ZS, Malvern, UK).

EXAMPLES

Example 1: Fabrication Process of Nanodiamonds (NDs) from Total Suspended Particulate Matter (TSPM) and PM.SUB.10

[0077] The ambient air containing particulate pollutants with the size ranges from 10-100 μm in diameter (TSPM) are used for fabrication of blue fluorescent nanodiamonds. The collected TSPM (5-6 g) was mixed with 100 mL of hydrogen peroxide (20-30%) in a Teflon beaker and the mixture was then ultrasonicated (frequency: 20 kHz) in a microprocessor-based ultrasonicator (Model-Power Sonic) for about 1 hrs at an atmospheric pressure and temperature. Polytetrafluoroethylene membrane filter (˜0.22 μm) was used to filter the resultant mixture. The filterate was then centrifuged at about 1400 rpm for 1 hour. The supernatant was carefully taken and treated with nitric acid to remove the atmospheric contaminants or impurities. The nitric acid treated extract was then neutralized by adding ammonia solution drop wise. This neutral extract was concentrated using ultrafiltration and rotary evaporation and kept in a refrigerator at 4° C. for subsequent analysis (FIGS. 2 and 3).

[0078] FIG. 4 illustrates the micrographs of the Transmission Electron Microscopic Technique used to determine the microstructure/nanostructure of nanodiamonds prepared from TSPM. The micrographs clearly show the formation of nanodiamonds. The formed nanodiamonds are unagglomerated types (FIG. 4a) and distributed uniformly sized with a crystalline phase which is confirmed by Fast Fourier Transform (FFT) pattern [Fourier transforms infrared spectroscopy (FT-IR; System-2000, Perkin-Elmer)] (FIG. 4c). The chemical composition was also determined by using energy-dispersive spectroscopy which indicated that the TSPM derived NDs predominantly comprises of carbon and oxygen (FIG. 4b) and also free from impurities. The diameter of the nanodiamonds was estimated to be in the range of 3-6 nm (FIG. 4d).

[0079] At high-resolutions, electron beam analysis (HRTEM) [JEOL JEM 2100] of nanodiamond prepared from TSPM is illustrated in FIG. 5. The interplanar spacing (d spacing) of the crystal lattice was found to be in the range of 0.220-0.266 nm (2.20-2.66 Å) in the micrograph (FIGS. 5a and 5b) which indicates the presence of nanodiamond. These results are found to be in good agreement with the diamond phases of a cubic structure having lattice planes (111). The FFT image also revealed that the particles are hexagonal with a crystalline structure (FIGS. 5c and 5d). The elemental mapping of carbon and oxygen are also shown in FIGS. 5e and 5f, respectively. The TEM/HRTEM images, elemental characterizations, and FFT measurements of the interplaner lattice plane revealed the presence of nanodiamond particles in the TSPM derived samples rather than other carbon particles.

[0080] The X-ray diffraction (XRD) [Rigako, Ultima IV] analysis of a nanodiamond prepared from TSPM are shown in FIG. 6a, confirming the crystallites of the nanodiamond having a plane of the cubic structure. A broad peak observed at the ‘d’ spacing value of 4.16 Å) (2θ=21.3° indicates the presence of silica substrate and the second peak found at 2θ=26.3° (d spacing value=3.38 Å) belongs to the crystal plane of graphite (002). The peak at 20°-30° corresponded to the plane (002) of crystal graphite. The broad peak at 26° attributed to the nanodiamonds surrounded by an amorphous carbon matrix with abundant oxygen-containing functional. The other peaks observed at 2θ=43.22° (d spacing value=2.0 Å) and 2θ=75.1° (d spacing value=1.26 Å) corresponding to the (111) and (220) cubic planes of the diamond, which indicated that the structure of TSPM-derived NDs crystal is cubic. This analysis revealed that the formed NDs consist of both sp.sup.2 and sp.sup.3 hybridized carbon structure.

[0081] FIG. 6b illustrates the FT-IR (System-2000, Perkin-Elmer) spectral analysis of the TSPM-derived NDs. The peak observed at 660-685 cm.sup.−1 is due to the absorption of C—H bonds at the sp.sup.3 hybridized carbon atom. The peak observed at 806 cm.sup.−1 is assigned to the NO.sub.2 group. The absorption peak observed in the range of 1027-1068 cm.sup.−1 and 1385-1400 cm.sup.−1 is due to the stretching vibration of C—O and OH group along with other oxygen-containing functional groups, respectively. The absorption band is found within the range of 1630 cm.sup.−1 corresponding to the bending vibration of hydroxyl (O—H) and carbonyl (C═O). In this investigation, the absorption bands observed for the hydroxyl groups are found to be more predominant over the carbonyl groups which indicate high solubility in water.

[0082] The Raman spectra (Horiba Jobin Vyon, Model LabRam HR) show mainly three absorptions bands for TSPM-derived NDs samples (FIG. 6c). The NDs prepared from TSPM samples is evident from the peak at 1320 cm.sup.−1, which is due to the phonon confinement effect. The first Raman peak ranging from 1320-1350 cm.sup.−1 indicating near the position of D-band for sp.sup.3 hybridized carbon. The obtained diamond particle exhibits mainly Raman scattering peak at 1333 cm.sup.−1. The second peak in the Raman spectra occurs in the range of 1435-1475 cm.sup.−1 specifies the D-band corresponding to the sp.sup.3 hybridised structure of carbon. The third peak observed at 1600 cm.sup.−1 and 1620 cm.sup.−1 referred to as G-band attributed to the sp.sup.2 structure of carbon. The Raman analysis revealed that the nanodiamond particles are dominantly present in the TSPM-derived sample rather than that of graphite.

[0083] The photo-optical properties of the TSPM-derived ND sample were investigated by using ultraviolet (UV-Vis) spectroscopy and FL spectroscopy (UV-visible; Analytik Jena, SPECORD200, Germany), fluorescence spectroscopy (FL; Horiba Fluorlolog-3). FIG. 7a shows the UV-visible spectroscopic analysis of the NDs samples obtained from TSPM samples. The absorption peak observed at 210 nm (5.9 eV) is due to the π-π* and n-π* transition of C═C and C═O bonds present in the NDs samples, respectively. This peak attributed to the intrinsic absorption of nanodiamond that is larger than a diamond of 5.5 eV because of minor size-induced blue shift.

[0084] FIG. 7b shows the FL spectra of produced NDs samples under the excitation wavelength of 280-340 nm, at an increment of 20 nm. The FL properties of the TSPM derived NDs sample is observed to be excitation dependent as depicted in FIG. 7b. With the increase of excitation wavelength, the FL spectra of NDs sample is observed to be shifted from red to green and yellow regions which signify as a major characteristic of nanodiamond. This phenomenon is occurred due to the presence of numerous fluorophore or chromophore systems (aromatic and oxidation groups) in NDs, which is also confirmed from the FT-IR as discussed above.

[0085] The TSPM-derived NDs samples are found to be blue-fluorescence under UV-light (at 365 nm) with considerable intensity as shown in FIG. 7c-ii, which is one of the fascinating properties of nanodiamonds.

Example 2: Fabrication of Nanodiamonds (NDs) from Particulate Matter (PM.SUB.10.)

[0086] The same experiment as outline in Example 1 was conducted with the atmospheric particulate matter (PM.sub.10 having the aerodynamic sizes of 2.5-10 μm) in the same manner.

[0087] FIG. 8, shows the TEM image of nanodiamonds prepared from PM.sub.10 which are agglomerated types. TEM images show the formation of different sizes of carbon nanocrystals (FIG. 8a). Energy-dispersive spectroscopy (EDS) clearly shows the presence of carbon and oxygen predominantly in PM.sub.10 derived ND samples (FIG. 8b) and also free from impurities with FFT pattern shown in FIG. 8c. The diameter of these nanodiamonds was estimated to be in the range of 10-24 nm (FIG. 8d).

[0088] FIG. 9 illustrate the micrograph of HRTEM analysis. The micrograph shows the interplane spacing of 0.218-0.321 nm (2.18-3.21 Å) (FIGS. 9a and b), which revealed the presence of nanodiamond phases. The FFT (FIGS. 9c and d), measurements of the interplaner lattice plane revealed the presence of nanodiamond particles in the PM.sub.10-derived samples rather than other carbon particles.

[0089] The XRD analysis of PM.sub.10 derived ND sample (FIG. 10a) shows a broad peak peak at 26° attributed to the nanodiamonds surrounded by an amorphous carbon matrix with abundant oxygen-containing functional groups. The peak at 20°-30° corresponded to the plane (002) of crystal graphite as the similar results of TSPM derived NDs sample.

[0090] The FTIR analysis (FIG. 10b) of the PM.sub.10 derived ND samples showing the presence of C—H, C—O, C═O, and O—H group predominantly which indicates that the PM.sub.10 derived ND samples are highly functionalized and soluble in water.

[0091] Raman Analysis of ND samples from PM.sub.10 (FIG. 10c) also shows similar results as of TSPM derived ND samples. This analysis shows the presence of both the characteristic bands of ‘G’ and ‘D’. Raman scattering peak at 1320-1440 cm.sup.−1 indicates the presence of ND particle. This peak specifies the D band corresponding to the sp.sup.3 hybridized structure of carbon. The other peak observed at 1620 cm.sup.−1 referred to as G-band attributed to the sp.sup.2 structure of carbon. From this study, it is confirmed that the nanodiamonds fabricated from PM.sub.10 contains both sp.sup.3 and sp.sup.2 structure of carbon and dominance of diamond particles rather than the graphite.

[0092] FIG. 11a shows the UV-visible spectroscopic analysis of the NDs samples obtained from PM.sub.10 samples. The UV band was observed at 210 nm are due to the excitation of electrons from π-π* and n-π* transition of C═C and C═O bonds present in the NDs samples. The FL spectra (FIG. 11b) appeared at 420 nm, corresponding to blue fluorescence properties observed under UV-light at 365 nm (see FIG. 11c) as the similar results observed in TSPM derived ND sample.

Example 3: Surface Properties of NDs Prepared from Air Pollutants (TSPM and PM.SUB.10.)

[0093] Zeta potential is the electrostatic potential or net charge at the plane of particle-slipping. Zeta potential analysis was carried out (ZETASIZER; Model-Nano ZS, Malvern, UK) to know the stability and surface charge of the PMs-derived NDs. The Zeta potentials of the NDs were found to be in the range of −24 mV to −25 mV (FIGS. 12a and 12b), which indicated that produced NDs suspensions are stable. The negative zeta potential values were observed due to the presence of oxygen-containing functional groups, such as carbonyl (C═O) and carboxyl (COOH) groups which are dissociated in the surface of diamond particles.

Example 4: Toxicological Studies of NDs Prepared from Air Pollutants (TSPM and PM.SUB.10.)

[0094] Toxicological Studies:

[0095] As the air pollutants are considered as the most dangerous to human health, hence the toxicity of derived NDs from these C-sources were evaluated to know whether the produced product are toxic or non-toxic. Cells were sustained in RPMI medium improved with 10% Fetal bovine serum (FBS) and antibiotics at 37° C. in culture flasks with 5% CO.sub.2. Confluent monolayers (80%) of human normal kidney epithelial (NKE) cells were subjected to exposure of produced NDs at a dose of 5, 10, 20, 50, 100, 150, and 200 μg/mL for 24 hours.

[0096] Cytotoxicity Analysis and DNA Fragmentation or Genotoxicity Analysis:

[0097] Cytotoxicity was determined by using the Alamar Blue reduction bioassay. This method is based upon Alamar Blue dye reduction by live cells. After treatment with the produced NDs, the treatment medium was aspirated and 200 μL of Alamar Blue solution was added to each well and further incubated for 4 h at 37° C. The optical density of each well was measured by using a microplate reader with absorbance at 570 and 600 nm. Similar conditions were repeated three times and the well without any treatment was taken as a control. The results were expressed as a percentage over control.

[0098] The cytotoxicity analysis was performed to evaluate the toxicity levels of air pollutants (TSPM and PM.sub.10) derived NDs for their further utilization. The results demonstrated that NDs did not cause any change in the cell viability compared to those seen in the control study. FIG. 13a clearly shows that the cytotoxicity of NDs is considerably lower at all the concentration (i.e. 0-200 μg/mL). It revealed that the fabricated NDs are non-toxic on NKE cells. Thus, the air pollutants (TSPM and PM.sub.10) could also be a source for the fabrication of non-toxic blue fluorescent NDs and process may lead to the mitigation of atmospheric particulate pollution.

[0099] The extent of genotoxicity or fragmentation of DNA was assayed in genomic DNA samples with the help of electrophoresis technique, isolated from control as well as produced NDs treated cells, on agarose/ethidium bromide gels. After treatment, cells were washed with PBS followed by fixation with paraformaldehyde and mounted with a coverslip using the mounting media containing DAPI. Images were observed by confocal microscopy with an inverted laser scanning confocal microscope (Leica Microsystems, Germany).

[0100] The DNA fragmentation pattern treated in different cells compounds were examined. It was observed that the treatment with different compounds at a dose of 200 μg/mL for 24 hours did not cause DNA fragmentation (see FIG. 13b).

[0101] In summary, it can be confirmed that the air pollutants derived nanodiamonds are non-toxic for human kidney cell-line and it also even non-toxic at genetic level. This process will lead to the mitigation of atmospheric particulate pollution.

[0102] The main advantages of the present invention are: [0103] 1. By using the process of the present invention, typical blue-fluorescent nanodiamonds can be easily produced as compared to other drastic and tedious physical/chemical methods such as hydrothermal synthesis, ion bombardment, laser bombardment, microwave plasma chemical vapor deposition techniques, ultrasound synthesis, and electrochemical synthesis. [0104] 2. Using the process of the present application, the toxic air pollutants (TSPM and PM.sub.10) are converted into non-toxic high-value nanodiamonds (NDs). [0105] 3. Hydrogen peroxide used as oxidizing agent in the process is environment-friendly as compared to other chemical or acid solutions. [0106] 4. The process of the present invention is less time consuming.