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. 2021 Mar 5;11(4):157. doi: 10.1007/s13205-021-02689-9

Facile synthesis of reduced graphene oxide using Acalypha indica and Raphanus sativus extracts and their in vitro cytotoxicity activity against human breast (MCF-7) and lung (A549) cancer cell lines

Parthipan Punniyakotti 1, Rajasekar Aruliah 2, Subramania Angaiah 1,✉
PMCID: PMC7936010  PMID: 33758735

Abstract

In the present study, an eco-friendly approach is adapted for the synthesis of reduced graphene oxide (rGO’s) by a simple hydrothermal reaction using two plant extracts namely Acalypha indica and Raphanus sativus. After the hydrothermal reaction, GO turns into a black color from brown color, which indicates the successful reduction of graphene oxide. Further, various characterization techniques such as UV–Vis spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction is used to confirm the physicochemical properties of synthesized rGO’s. Raman analysis confirms the reduction of GO by noticing an increase in the ID/IG ratio significantly. Field emission scanning electron microscopy and transmission electron microscopy clearly show the morphology and crystalline nature of rGO’s. FT-IR spectrum confirms that the bioactive molecules of the plant extract (i.e. polyphenols, flavonoids, terpenoids, etc.) playing a key role in the elimination of oxygen groups from the GO surface. Further, the synthesized rGO’s are tested for their potential against human lung and breast cancer cell lines. A significant cancer cell inhibition activity is obtained even in the less concentration of rGO’s with IC50 values for lung cancer cell lines are 38.46 µg/mL and 26.69 µg/mL for AIrGO and RSrGO, respectively. Similarly, IC50 values for breast cancer cell lines are 35.97 µg/mL and 33.22 µg/mL for AIrGO and RSrGO, respectively.

Keywords: Reduced graphene oxide, Green synthesis, A549 human lung cancer cell, Cytotoxicity

Introduction

Cancer is commonly known as an uncontrolled growth of tumor cells which vigorously affect the normal body cells and damage the specific organs or entire systems. Cancer is a severe and most serious problem and considered the world's second-largest non-communicable disease and recorded millions of mortalities each year (Pugazhendhi et al. 2018). Among various cancers, lung cancer is listed as the deadliest about 20%. Similarly, breast cancer is also considered as most common at the same time most severe cancer for women. Control and treatment of these kinds of cancers are most difficult with the current methods. Recently, nanomaterials and nanocomposites are tested as promising tools to treat cancer cells without harming the normal cells (Prabhu et al. 2019; Hariharan et al. 2020; Munawer et al. 2020). Nanoparticles including silver, gold, copper, and zinc are tested for anticancer activity and found considerable cell inhibition activity. Using these metal nanoparticles perhaps has limitations as high cost and toxic nature, which need to be reduced with potential candidates. Recently, carbon-based nanomaterials (i.e. carbon nanotubes) are being tested to control the growth of cancer cells (Yu et al. 2018; Saleemi et al. 2020). Only very few reports are available on the use of graphene for anti-cancer studies and hence much scope is available in this direction.

Graphene is a carbon-based 2D material with extraordinary physical, chemical, and mechanical properties, which has great attention among the scientific community to develop/use in different applications including supercapacitors, transistors, transparent electrode, polymer composites, and sensors (Du et al. 2019; Li et al. 2018; Chuah et al. 2020). The most popular and successful method for the exfoliation of graphene from graphite is Hummer’s method (Samuel et al. 2020a). In this method, strong acids and bases are used to exfoliate few layers or multi-layer graphene in the form of graphene oxide (GO). In most applications, GO is widely used as graphene material because the pure form of graphene is high-cost material and cannot use in bulk quantity. Reduced graphene oxide (rGO) is a potential alternative material, which can be used for diverse applications (Norahan et al. 2019; Gnanasekar et al. 2020).

The chemical reduction method is the most useful technique for the bulk synthesis of graphene at a low cost (Samuel et al. 2020b). Chemical reduction of GO could be done with reducing agents such as hydrazine, hydroquinone, amino acids, sodium borohydride, metal hydrides, sodium hydroxide, etc. Chemical reducing agents are classified as strongly acidic or highly toxic. This toxic nature of reducing agent restricts their use in biomedical applications. This problem can be overcome by utilizing the eco-friendly reducing agent (Mahata et al. 2018). Plants and their derivatives are one of the most potentials and eco-friendly candidates that could be used for the reduction of graphene oxide (Padhi et al. 2017). This green synthesis method having numerous advantages such as easy availability, low cost, and suitable for biomedical applications (Khenfouch et al. 2016; Bhattacharya et al. 2017).

In recent times, different types of plants and their derivatives are being utilized for the deoxygenation of GO such as Plectranthus amboinicus leaf extract (Zheng et al. 2016), Fenugreek seeds (Singh et al. 2016), Aloe vera (Bhattacharya et al. 2017), black soybean (Chu et al. 2016), lemon extract (Sha and Badhulika 2018), rose water (Haghighi et al. 2013), Eucalyptus leaf extract (Jin et al. 2018), Euphorbia heterophylla (L.) (Lingaraju et al. 2019), Platanus orientalis leaf extract (Xing et al. 2016), pomegranate juice (Tavakoli et al. 2015), Mangifera indica L., and Solanum tuberosum L. (Sadhukhan et al. 2016), Peltophorum pterocarpum pollen grains extract (Rahman et al. 2014), Ocimum sanctum L. leaf extract (Mahata et al. 2018). In addition, some other eco-friendly materials are also used for the reduction of the GO such as bagasse (Gan et al. 2018), and silk sericin (Maddinedi et al. 2018).

Still now, a very limited number of plant sources are only being tested for the green reduction of GO, even in some cases a few of the limitations are found with these plant sources such as low yield, long processing times, un-availability of the reducing agents. For the present study, two different types of green materials are selected such as Acalypha indica (Indian acalypha) and Raphanus sativus (white radish). Both the selected plants are easily available and also very cheap material. Especially, radish is found around the world and easily cultivable did not require any special condition for their growth. Similarly, A. indica is a well-known plant species in India and is commonly found as the weed plants, which contain a lot of bioactive components and are used as a natural medicine to cure some of the illnesses.

In the current study, a simple method is followed to synthesize reduced graphene oxide using two different types of green materials such as Acalypha indica and Raphanus sativus. The synthesized rGO’s are analyzed using X-ray diffraction, UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Finally, the prepared rGO’s are subjected to cytotoxicity studies against the human breast and lung cancer cell lines in detail.

Materials and methods

Materials

Graphite powder, ethylene diamine tetra acetic acid (EDTA), sodium chloride, potassium chloride, disodium hydrogen phosphate, and potassium dihydrogen phosphate were purchased from Hi-media. 3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyltetrazolium bromide was purchased from ThermoFisher Scientific. Potassium permanganate, hydrogen peroxide, and ethanol were purchased from Sigma-Aldrich. Sodium nitrate, sulphuric acid, hydrochloric acid, methanol, and dimethyl sulfoxide (DMSO) were obtained from Merck. All the obtained chemicals are AR grade and used without any purification. For this study, Acalypha indica is collected from the Pondicherry University campus and Raphanus sativus is purchased from a local vegetable shop at Kalapet, Puducherry.

Synthesis of graphene oxide

Graphene oxide (GO) was synthesized by a modified Hummers method (Hummers and Offerman 1958). Briefly, 1 g of graphite flake was ground with 50 g of sodium chloride for 10 min. Sodium chloride was dissolved in deionized water and separated by filtration (nearly 15% carbon could be lost in this step). The remaining graphite flake was stirred with the addition of 23 mL of sulphuric acid (98%) for 8 h. Further, 3 g of potassium permanganate was gradually added and maintained a temperature of less than 20 ºC. The above mixture was stirred for 30 min at 35–40 ºC, followed by 45 min stirring at 65–80 ºC. Further, 46 mL of deionized water was added and then stirred for 30 min at 98–105 ºC. The above reaction was stopped by the inclusion of 140 mL of distilled water along with 30% hydrogen peroxide solution (10 mL). Finally, the above mixture was washed several times by centrifugation using 5% hydrochloric acid followed by deionized water. Finally, the obtained GO was dried at room temperature using a vacuum oven.

Preparation of plant extracts

A healthy and fresh leaf of Acalypha indica (Indian acalypha) was collected and cleaned with running tap water to remove the soil or any dirt material from the surfaces of leaves. Further washed with distilled water two times. These leaves were dried at 50 ºC for 4 h using a hot air oven to get dried leaves. These dried leaves were ground well into a fine powder. 5 g of this powder was taken in 50 mL of distilled water and kept at 80 ºC for 1 h and then cooled. After cooling, the leaf extract was filtered using No. 1 Whatman filter paper. Similarly, the root extract of Raphanus sativus (white radish) was prepared by adapting the above-said procedure.

Hydrothermal synthesis of rGO’s

For the facile reduction of GO, 30 mg of synthesized GO was dissolved in 30 mL (1 mg/mL) of each plant extract separately. Further, both solutions were subjected to ultra-sonication for 30 min. These mixtures were transferred into separate Teflon-lined autoclave and kept at 100 °C for 12 h. After the hydrothermal reaction was completed, waited until the temperature drops down to room temperature, and the reduced GO was centrifuged at 8000 rpm for 15 min to separate from the solution. Further, the separate was washed many times with deionized water followed by a final wash with ethanol. Finally, the obtained rGO’s were vacuum dried at 60 °C for 12 h and used for further characterization and studies. Obtained rGO’s were named AIrGO and RSrGO with their reduction extracts of Acalypha indica and Raphanus sativus, respectively.

Characterizations

To confirm the functional molecules present in the plant extract, both extracts were subjected to the FTIR analysis (Model: JASCO-460, Japan). The crystalline property of the rGO’s was analyzed using powder XRD (Model: Rigaku-Ultima IV, Japan) using nickel filtered Cu–Kα radiation (λ = 0.154 nm). The phase information was confirmed by Raman spectroscopy with a confocal micro-Raman spectrometer (Renishaw RM 2000, United Kingdom) under a 20 mW InnovaAr+ ion laser at 785 nm. Optical properties were confirmed by UV–Vis spectrophotometer (Model: Varian-5000, Australia). Morphology of both GO and rGO’s was confirmed by FESEM (Model: Carl Zeiss-SUPRA-55, Germany) and also with high-resolution transmission electron microscopy (HR-TEM, Model: Technai G2-F30STwin, USA) operated at 300 kV.

In vitro cytotoxicity studies

The human lung cancer cell lines (A549) and breast cancer cell lines (MCF-7) are purchased from National Centre for Cell Science (NCCS), Pune, India, and grown and maintained using eagles minimum essential medium which containing 10% of fetal bovine serum (FBS). Both cell lines were maintained at 37 °C with 5% of CO2 along with 95% of air at 100% relative humidity. The monolayer cells are separated with trypsin–EDTA to make single-cell suspensions. Hemocytometer was used for the viable cell counts and diluted using 5% FBS medium to obtain the final density of 1 × 105 cells/mL. A 100 µL/well of cell suspension was added into 96-well plates incubated as earlier stated. For the testing purposes, rGO’s were prepared using DMSO solution with different concentrations (µg/mL: 6.5, 12.5, 25, 50, and 100). After 24 h of the incubation, aliquots of 100 µL of each concentration of these sample dilutions were included in suitable wells. Further, all the plates were incubated in the above-mentioned incubation condition. The medium alone without rGO was used as the control and all the experiments were repeated three times. After the incubation period, 15 µL of MTT (5 mg/mL) was prepared in phosphate-buffered saline (PBS) and included in each well and further incubated for 4 h at 37 °C. The medium with MTT was then flicked off and the formazan crystals were formed during the incubation. This was solubilized using 100 µL of DMSO and the absorbance values were measured at 570 nm using a microplate reader.

Results and discussion

Reduced graphene oxide was synthesized using two plant extracts. GO added with plant extracts are initially subjected for sonication and observed as brown colour in nature. After the hydrothermal reaction, this brown colour was turned with a dark black colour, which indicates the complete reduction of GO. Further, reduced graphene oxide is subjected to various characterization to confirm its physio-chemical properties.

UV–Visible spectroscopic studies

UV–vis absorption spectra of GO and rGO’s were illustrated in Fig. 1a. From this figure, it is very vibrant that GO shows a peak at 225 nm due to the π–π* transition of graphitic C–C bonds and a shoulder at 313 nm attributes the π–π* transition of C-O bonds. As the reduction reaction happens successfully the characterized peak increased to 272 nm for AIrGO and 282 nm for RSrGO, respectively. It confirms that electronic conjugation is restored. The interestingly strong absorption peak is found at around 200 nm for both rGO’s which indicate the strong adsorption between the graphene and bioactive molecules of plant extracts (i.e. polyphenol) (Singh et al. 2016; Manchala et al. 2019).

Fig. 1.

Fig. 1

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a UV–Vis absorption spectra, b XRD patterns of exfoliated GO, AIrGO, and RSrGO

XRD analysis

The crystalline structure of synthesized GO and rGO’s are confirmed using powder X-ray diffractions and are shown in Fig. 1b. Graphite flakes show a characteristic peak at 2ϴ of 26.6°. While graphite undergoes chemical oxidation, this peak is shifted to 2ϴ of 10.34°, it is attributed to the (001) plane and revealed that graphite is completely oxidized as graphene oxide. Further, both plant extracts are used for the reduction of GO and found broader peaks at 2ϴ of 25.55° for RSrGO and 2ϴ of 26.31° for AIrGO, which is attributed to the (002) plane of rGO respectively, and JCPDS Card No. is matched with 75-1621. Similarly, Rani et al (2019) synthesized rGO using an eco-friendly approach with marigold flower extract. From XRD analysis, it is confirmed that both plant extracts are efficiently reduced the graphene oxide (Gan et al. 2018).

Raman studies

Raman spectroscopy is one of the most reliable and most potent tools to distinguish both GO and rGO’s from each other. A Raman spectrum is used to explore the graphene defects, layers, and their electronic structure. Typically, Raman analysis of the graphene materials is based on the formation and intensity of D and G bands. In general, the G band is formed based on the first-order scattering of the E2g photon of sp2 carbon atoms, and the D band is formed because of the breathing mode of k-point photons of A1g symmetry (Singh et al. 2016). Typical Raman spectra of the chemically synthesized GO and rGO’s are presented in Fig. 2a. In the case of graphene oxide, G and D bands are observed at 1601 cm−1 and 1329 cm−1, respectively. After the reduction by plant extracts, D bands were shifted to 1317 cm−1 for both rGO’s and G bands is detected at 1600 cm−1 and 1595 cm−1 for RSrGO and AIrGO, respectively. Similarly, the ID/IG is measured for both GO and rGO’s and found that 1.02 for GO, which is slightly increased to 1.15 and 1.22 for RSrGO and AIrGO, respectively. An increase in ID/IG ratio confirms the presence of unrepaired defects after the removal of negatively charged oxygen moiety of GO (Lingaraju et al. 2019). It is also noticed that an increase in the intensity of the D band of rGO’s was due to the introduction of defects (Haghighi and Tabrizi 2013; Gan et al. 2018).

Fig. 2.

Fig. 2

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a Raman analysis, b FT-IR spectra of exfoliated GO, AIrGO, and RSrGO

FT-IR analysis of GO and rGO’s

The functional molecules present in the synthesized GO and rGO’s are confirmed by FTIR spectra as illustrated in Fig. 2b. FTIR spectrum of GO displays a broadband at 3427 cm−1 which indicates the presence of O–H stretching mode. Another peak at 1717 cm−1 confirmed the occurrence of C=O stretching vibration of carboxylic acid and a strong peak at 1627 cm−1 denotes the existence of C=C stretching group from sp2 carbon rings. Another sharp peak at 1383 cm−1denotes the C–OH stretching (carboxyl) initiating from the carboxylic acid. An intense peak found at 1124 cm−1 is due to the C–O stretching of epoxy (Haghighi and Tabrizi, 2013; Basiri et al. 2018). The presence of these functional groups in the GO confirmed that the oxidation has occurred in the graphite (Lingaraju et al. 2019). Further, FT-IR analysis of rGO’s shows some of the absorption peaks of oxide groups are decreased in their intensity, which confirmed that AIrGO and RSrGO are actively reduced GO.

Microscopic studies

FE-SEM was used for the surface analysis and are presented in Fig. 3. The graphene oxides (Fig. 3a) were formed as bundles and not that much exfoliated. Also noted, GO sheets are different from the graphite by the existence of vast oxygen-containing groups over the surface, which reduces electrical conductivity. Besides, chemically synthesized GO was found as thicker, which might be due to that many layers have been stacked into each one and found as a cluster that is opaque in nature (Lingaraju et al. 2019). FE-SEM images of AIrGO and RSrGO were presented in Fig. 3b and c, respectively. From these images, it was so clear that reduced graphene oxide sheets are well exploited, and also seems thickness was reduced than GO. This observation strongly revealed that biologically active molecules present in the plant extract play a crucial role to remove oxygen from the surface of GO (Tavakoli et al. 2015).

Fig. 3.

Fig. 3

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FESEM images of a exfoliated GO, b AIrGO, and c RSrGO

Similarly, both reduced graphene oxides are subjected to the transmission electron microscopy observation to reveal the structure and crystalline nature of the green synthesized rGO’s. Bright-field micrographs and selected area electron diffraction (SAED) patterns of AIrGO and RsrGO are presented in Fig. 4a, b and c, d, respectively. From Fig. 4a, c it was very clear that both rGO’s are well exploited and both wrinkles and folds are noticed in the graphene sheets, which is characteristic nature of the well-exfoliated single graphene sheet (Kadiyala et al. 2018). Also, both SAED patterns are showing a sharp ring, which revealed that synthesized rGO’s has better crystalline properties (Rahman et al. 2014).

Fig. 4.

Fig. 4

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TEM and SAED pattern of AIrGO (a, b) and RSrGO (c, d)

FT-IR analysis of plant extracts

The active molecules existing in the plant extracts were confirmed using FT-IR examination. Figure 5a shows the FT-IR spectrum of Acalypha indica extract, a broad peak noticed at 3394 cm−1 confirms the presence of alcohols and phenols. A peak at 2929 cm−1 is because of the occurrence of O–C stretching frequency. Another peak at 1606 cm−1 is due to the presence of C=O stretching and a peak at 1400 cm−1 represents the existence of N=O group. A small peak at 1278 confirms the presence of alcohol, carboxylic acid, ether, or ester (C–O stretch), and a peak at 547 cm−1 specifies the existence of alkyl halides (Menon et al. 2017). In the same way, Fig. 5b shows the FT-IR spectrum of aqueous extract of Raphanus sativus. A broad peak observed in between 3300 and 3400 cm−1 represents the –OH stretching group which confirms the presence of phenolic compounds. An intense peak at 1630 cm−1 is found because of the existence of –C=C which is assigned to amine and amide bonds of protein. The absorption peak noticed at 1385 cm−1 represents the methyl group and peaks observed in 1057 and 1259 could be owing to C–N stretching of amines. A peak at 917 cm−1 is found due to the C–H stretching vibration of the alkene group. The peaks at 624 and 590 are due to the presence of alkyl halide stretching (Singh et al. 2017). The FTIR analysis of both plant extracts revealed the presence of a huge amount of polyphenols along with other flavonoids or terpenoids, which play a key role in the reduction of GO. Both plants are selected based on their constitution since both plants are enriched with polyphenol. These secondary metabolites are responsible for the efficient reduction characteristics of GO.

Fig. 5.

Fig. 5

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FT-IR spectra of AIE and RSE plant extracts. AIE Acalypha indica extract, RSE Raphanus sativus extract)

Cytotoxic activity on cancer cell lines

The anticancer potential of both green synthesized rGO’s were tested against human cancer cell lines, breast (MCF-7) and lung (A549) cancer cell lines. In general,3-[4,5-dimethylthiazol-2-yl] 2,5-diphenyltetrazolium bromide (MTT) assay is working as follows; MTT is a water-soluble yellow-colored tetrazolium salt. Succinate-dehydrogenase enzyme usually found in the mitochondrial portion of the living cells, which cleave the tetrazolium ring, and convert MTT into the insoluble purple color formazan. The formazan level is acting as an indicator of the viable cells in a growth medium. Similarly, MTT assay is carried out and In vitro cytotoxic activity of AIrGO and RSrGO on human lung cancer cell lines (A549) were presented in Figs. 6 and 7, respectively. From these figures, it is very clear that A549 cancer cells are highly susceptible to the reduced graphene oxide even in the very less concentration and cell viability is decreased with the increasing concentrations. Figure 8 clearly illustrates the percentage of cancer cell inhibition with various concentrations of rGO’s. About 61.34% of cell inhibition is obtained at the maximum concentration (100 µg/mL) of AirGO tested with IC50 value as 38.46 µg/mL of concentration. Similarly, RSrGO shows maximum lung cancer cell inhibition of about 65.84% at the concentration of 100 µg/mL with an IC50 value of 26.69 µg/mL. A similar inhibition level is obtained for graphene/nickel oxide nanocomposites (Rajivgandhi et al. 2019). The IC50 value obtained from this is much lesser than other reported studies (Rani et al. 2019). For instance, Kavinkumar et al (2017) found 160 µg/mL as IC50 value for rGO against A549 cell lines. This statement infers that even a very lesser concentration tested rGO’s shows effective activity against the lung cancer cell lines.

Fig. 6.

Fig. 6

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In vitro cytotoxicity activity of human lung cancer cell lines (A549) treated with different concentrations of AIrGO: a control, b 6.5 µg/mL, c 12.5 µg/mL, d 25 µg/mL, e 50 µg/mL and f 100 µg/mL. Scale bar = 200 μm

Fig. 7.

Fig. 7

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In vitro cytotoxic activity of human lung cancer cell lines (A549) treated with different concentrations of RSrGO: a control, b 6.5 µg/mL, c 12.5 µg/mL, d 25 µg/mL, e 50 µg/mL and f 100 µg/mL. Scale bar = 200 μm

Fig. 8.

Fig. 8

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Percentage of cell inhibition in the presence of different concentrations of rGO a human lung cancer cell lines (A549) and b human breast cancer cell lines (MCF-7)

Similarly, both rGO’s were tested against human breast cancer cell lines (MCF-7) as well and are presented in Figs. 9 and 10. Interestingly, both rGO’s were effectively functioning against the MCF-7 cell lines at the In vitro condition. Cell viability is diminished with increasing the concentrations of both rGO’s. Cell inhibition with different percentage is presented in Fig. 8. The maximum cell inhibition of about 68.55% is obtained at the concentration of 100 µg/mL of AIrGO with IC50 value as 35.97 µg/mL and 71.15% of cell inhibition is obtained in the presence of RSrGO at the concentration of 100 µg/mL with IC50 value as 33.22 µg/mL.

Fig. 9.

Fig. 9

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In vitro cytotoxic activity of human breast cancer cell lines (MCF-7) treated with different concentrations of AIrGO: a control, b 6.5 µg/mL, c 12.5 µg/mL, d 25 µg/mL, e 50 µg/mL and f 100 µg/mL. Scale bar = 200 μm

Fig. 10.

Fig. 10

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In vitro cytotoxicity activity of human breast cancer cell lines (MCF-7) treated with different concentrations of RSrGO: a control, b 6.5 µg/mL, c 12.5 µg/mL, d 25 µg/mL, e 50 µg/mL and f 100 µg/mL. Scale bar = 200 μm

The anticancer activity of reduced graphene oxide may be in the following ways, firstly graphene material might observe over the exterior membrane of cancer cells and they perhaps interact with the extra-cellular matrix or plasma membrane and penetrate the cell through binding to receptors, diffusion, and endocytosis (Tabish et al. 2017; Lingaraju et al. 2019; Rajivgandhi et al. 2019). The toxicity of reduced graphene oxide mainly depends on their functional properties, after penetrating the cells, which could produce reactive oxygen species, that make some stress. Overall, these changes will lead to the loss of their functional properties and all the internal organelles will be damaged. Once graphene reached the nucleus, which might cause DNA damage and leads to cell death (Gurunathan et al. 2015; Rajivgandhi et al. 2019).

Conclusion

Graphene has more attention for biomedical applications due to its extraordinary physiochemical properties. In this study, deoxygenation of GO is done using plant extracts such as Acalypha indica and Raphanus sativus. XRD and Raman analysis strongly revealed the successful reduction of GO by a simple hydrothermal method using plant extracts. In Raman’s study, ID/IG is measured for both GO and rGO’s and is found to be 1.02 for GO and 1.15 and 1.22 for RSrGO and AIrGO, respectively. Increasing the ID/IG ratio confirms that the presence of unrepaired defects after the removal of negatively charged oxygen moieties of GO. FE-SEM and TEM studies confirm that rGO’s are well exploited than GO. Finally, both rGO’s are tested against the human cancer cell lines including the lung (A549) and breast (MCF-7) cancers. A significant cancer cell inhibition activity is obtained even in the less concentration of rGO’s. Hence, this eco-friendly graphene material can be used as a potential material for biomedical applications.

Acknowledgements

Dr. P. Parthipan, gratefully acknowledges the Science and Engineering Research Board (SERB), Department of Science and Technology (DST), for providing research fellowship under the National Postdoctoral Fellowship (PDF/2017/001134). The authors are very grateful to the Central instrumentation facility, Pondicherry University, Puducherry for providing the instrumentation facility.

Declarations

Conflict of interest

The authors declare no competing financial interest.

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