Photocatalytic Degradation of Methylene Blue and Anticancer Response of In2O3/RGO Nanocomposites Prepared by a Microwave-Assisted Hydrothermal Synthesis Process

The incorporation of graphene with metal oxide has been widely explored in various fields, including energy storage devices, optical applications, biomedical applications, and water remediation. This research aimed to assess the impact of reduced graphene oxide (RGO) doping on the photocatalytic and anticancer properties of In2O3 nanoparticles. Pure and In2O3/RGO nanocomposites were effectively synthesized using the single-step microwave hydrothermal process. XRD, TEM, SEM, EDX, XPS, Raman, UV–Vis, and PL spectroscopy were carefully utilized to characterize the prepared samples. XRD data showed that synthesized In2O3 nanoparticles had high crystallinity with a decreased crystal size after RGO doping. TEM and SEM images revealed that the In2O3 NPs were spherical and uniformly embedded onto the surface of RGO sheets. Elemental analysis of In2O3/RGO NC confirmed the presence of In, O, and C without impurities. Raman analysis indicated the successful fabrication of In2O3 onto the RGO surface. Uv–Vis analysis showed that the band gap energy was changed with RGO addition. Raman spectra confirmed that In2O3 nanoparticles were successfully anchored onto the RGO sheet. PL results indicated that the prepared In2O3/RGO NCs can be applied to enhance photocatalytic activity and biomedical applications. In the degradation experiment, In2O3/RGO NCs exhibited superior photocatalytic activity compared to that of pure In2O3. The degradation efficiency of In2O3/RGO NCs for MB dye was up to 90%. Biological data revealed that the cytotoxicity effect of In2O3/RGO NCs was higher than In2O3 NPs in human colorectal (HCT116) and liver (HepG2) cancer cells. Importantly, the In2O3/RGO NCs exhibited better biocompatibility against human normal peripheral blood mononuclear cells (PBMCs). All the results suggest that RGO addition improves the photocatalytic and anticancer activity of In2O3 NPs. This study highlights the potential of In2O3/RGO NCs as an efficient photocatalyst and therapeutic material for water remediation and biomedicine.


Introduction
Nanocomposites (NCs) have shown promising potential in medical applications, including antibacterial, cancer diagnostics, and therapy [1][2][3][4]. Among these nanocomposites (NCs), nanomaterials based on metal oxide nanoparticles (NPs) are attracting interest in a number of areas of science and technology due to their desirable properties, such as being low-cost, non-toxic, renewable, and excellent semiconductors [5,6]. Furthermore, graphene is a sp 2 -bonded hexagonal network of carbon atoms [7]. It has excellent properties such as a high specific surface area, favorable electron transportation, tunable band gap, good thermal and electrical conductivity, and biocompatibility [8,9]. On the other hand, graphene oxide (GO) and reduced oxide (RGO) have attracted significant attention due to their unique properties, such as high surface area, good electrical conductivity, and excellent chemical stability [10,11].
Several studies have investigated the photocatalytic degradation of methylene blue using metal oxide nanoparticles (NPs). For instance, [12] reported a significant degradation of MB under visible light irradiation using TiO 2 NPs. Similarly, other metal oxide nanoparticles, such as ZnO NPs have also exhibited promising photocatalytic properties for MB degradation [13]. The cytotoxicity of metal oxide NPs towards various cancer cell lines, including breast, lung, prostate, and liver cancer have been reported in numerous studies. For example, Kokila et al. [14] showed that silver oxide (Ag 2 O) NPs exhibited strong anti-cancer effects on lung cancer cells.
The incorporation of metal oxide NPs into graphene has been achieved through various approaches to synthesize novel nanocomposites (NCs), which solve certain challenges associated with pure metal oxide NPs [15,16]. For example, ZnO/RGO NCs [17], ZnO-MoS 2 /RGO NCs [18], MoS 2 -Fe 2 O 3 /RGO NCs [19], Ag/ZnO/RGO NCs [20], and Ce/ZnO/RGO NCs [21] have been successfully prepared and have potential in biomedicine and environmental remediation applications. Different approaches including chemical, physical, and biological methods have been used to synthesize metal oxide NPs with RGO as NCs [22][23][24]. Bibi et al. [25] reported the synthesis of Fe 2 O 3 -TiO 2 /RGO NCs through a hydrothermal approach, which demonstrated remarkable methyl blue degradation capabilities due to the synergistic effect between Fe 2 O 3 -TiO 2 NPs and RGO. Indium oxide nanoparticles (In 2 O 3 NPs) based on graphene have been extensively studied for potential applications such as high-performance supercapacitors [26,27], gas sensing [28], energy storage devices [29], biomedicine [30], and water remediation [31]. For example, Devi and Singh [32] reported that doping RGO in In 2 O 3 plays a role in improving the photocatalytic performance due to its surface area and improved charge separation.
This study aimed to enhance the properties of In 2 O 3 NPs by RGO doping on their photocatalytic and anticancer performance. XRD, SEM, TEM, EDX, XPS, Raman scattering, UV-Vis, and PL spectroscopy were used to characterize the synthesized samples. The results show that In 2 O 3 /RGO NCs exhibited superior photocatalytic activity compared to pure In 2 O 3 NPs. Cytotoxicity assessment demonstrated that In 2 O 3 /RGO NCs displayed increased cytotoxicity against human colorectal (HCT116) and liver (HepG2) cancer cells compared to In 2 O 3 NPs. These results indicate that In 2 O 3 /RGO NCs exhibit improved photocatalytic and anticancer properties.

Structural Study
The crystal structure and phase composition of prepared samples were analyzed by X-ray diffraction (XRD). Figure 1A shows XRD spectra of RGO, pure In 2 O 3 NPs, and In 2 O 3 /RGO NCs. As depicted in Figure 1Aa, XRD spectra of RGO demonstrate a characteristic peak of graphene at 26.1 • to (002) plane [33]. It can be seen in Figure 1Ac (622) planes. This phenomenon indicates that they were slightly shifting to a low angle ( Figure 1B). Results indicated that In 2 O 3 /RGO NCs were further crystallized due to their high peak intensity and sharp peak width, which were matched with earlier studies [34][35][36]. The average crystal sizes of pure In 2 O 3 NPs and In 2 O 3 /RGO NCs were 17 nm and 13 nm (estimated by the Debye Scherrer formula), respectively. It was observed that the average crystal sizes were decreased with RGO doping. XRD results show that the In 2 O 3 NPs were anchored on the surface of RGO due to the change in the intensities of peaks [28]. Obtained results agree with previous studies [36,37]. change in the intensities of peaks [28]. Obtained results agree with previous studies [36,37].

Morphological Study
TEM analysis was further applied to characterize the morphologies and particle sizes of prepared nanocomposites (NCs). Figure 2A-D presents the TEM images and a selected area electron diffraction (SEAD) pattern of RGO, pure In2O3 NPs, and In2O3/RGO NCs. It can be seen in Figure 2A that the TEM image of RGO was shown as thin and transparent sheets with wrinkles and folds. Thus, the thickness of the RGO sheets cannot be accurately determined from the TEM image [38]. We observe that the TEM image ( Figure 2B) of pure In2O3 NPs was uniformly distributed spherically as found in an earlier investigation [39]. As shown in Figure 2C, the In2O3 NPs were anchored onto the surface of the RGO sheets with a homogeneous dispersion owing to the interaction between RGO and In2O3 NPs [23,24,32,40]. Table 1 shows the average particle sizes of In2O3NPs and In2O3/RGO NCs, which were 12 nm and 10 nm, respectively. The crystal structure and orientation of the In2O3/RGO NCs are shown in the SEAD pattern ( Figure 2D). However, the SEAD pattern shows a series of diffraction rings and spots, which correspond to the planes and directions of the In2O3 and RGO crystals. The diffraction spots are indexed to the (222), (400), (440), (622), and (444) planes of In2O3, which agree with the standard JCPDS data (No. 01-089-4595). TEM results revealed that the In2O3 NPs were successfully attached to the surface of the RGO sheet as novel In2O3/RGO NCs.

Morphological Study
TEM analysis was further applied to characterize the morphologies and particle sizes of prepared nanocomposites (NCs). Figure 2A-D presents the TEM images and a selected area electron diffraction (SEAD) pattern of RGO, pure In 2 O 3 NPs, and In 2 O 3 /RGO NCs. It can be seen in Figure 2A that the TEM image of RGO was shown as thin and transparent sheets with wrinkles and folds. Thus, the thickness of the RGO sheets cannot be accurately determined from the TEM image [38]. We observe that the TEM image ( Figure 2B) of pure In 2 O 3 NPs was uniformly distributed spherically as found in an earlier investigation [39]. As shown in Figure 2C, the In 2 O 3 NPs were anchored onto the surface of the RGO sheets with a homogeneous dispersion owing to the interaction between RGO and In 2 O 3 NPs [23,24,32,40]. Table 1 shows the average particle sizes of In 2 O 3 NPs and In 2 O 3 /RGO NCs, which were 12 nm and 10 nm, respectively. The crystal structure and orientation of the In 2 O 3 /RGO NCs are shown in the SEAD pattern ( Figure 2D). However, the SEAD pattern shows a series of diffraction rings and spots, which correspond to the planes and directions of the In 2 O 3 and RGO crystals. The diffraction spots are indexed to the (222), (400), (440), (622), and (444) planes of In 2 O 3 , which agree with the standard JCPDS data (No. 01-089-4595). TEM results revealed that the In 2 O 3 NPs were successfully attached to the surface of the RGO sheet as novel In 2 O 3 /RGO NCs.  Figure 3A-D shows the SEM images with EDX spectra of pure In 2 O 3 NPs and In 2 O 3 /RGO NCs. As displayed in Figure 3A, the pure In 2 O 3 NPs were spherically shaped and uniformly distributed. EDX spectra ( Figure 3B) shows that the chemical element indium (In) and oxygen(O) were present in pure In 2 O 3 NPs without any impurities. It can be seen in Figure 3C Figure 3D. These percentages are in excellent agreement with the starting precursor. Additionally, Figure 4A-D shows the uniform distribution of the presence of In, O, and C elements in In 2 O 3 /RGO NCs, which further supports the EDX results obtained. All results suggest that the In 2 O 3 /RGO NCs were successfully prepared, which agrees with earlier studies [7,32,41,42].   Figure 3A-D shows the SEM images with EDX spectra of pure In2O3 NPs and In2O3/RGO NCs. As displayed in Figure 3A, the pure In2O3 NPs were spherically shaped and uniformly distributed. EDX spectra ( Figure 3B) shows that the chemical element indium (In) and oxygen(O) were present in pure In2O3 NPs without any impurities. It can be seen in Figure 3C that the In2O3 NPs were distributed and attached to the RGO surface. Similarly, the elemental compositions (In, O, and C) in In2O3/RGO NCs were confirmed in Figure 3D. These percentages are in excellent agreement with the starting precursor. Additionally, Figure 4A-D shows the uniform distribution of the presence of In, O, and C elements in In2O3/RGO NCs, which further supports the EDX results obtained. All results suggest that the In2O3/RGO NCs were successfully prepared, which agrees with earlier studies [7,32,41,42].     Figure 5A-D illustrates the XPS spectra of synthesized In2O3/RGO NCs. All elemental compositions (In, O, and C) of the In2O3/RGO NCs were shown in the surveyed XPS spectra ( Figure 5A). These results were supported by EDX and mapping results (Figures 3 and  4). Therefore, XPS spectra of In 3d are presented in Figure 5B, which shows the chemical states of indium (In) in the In2O3/RGO NCs. Hence, the two peaks were observed at 444 and 451.5 eV for In 3d5/2 and In3d3/2, respectively [36,43]. Earlier studies reported that these peaks are distinctive properties of indium (In) in the +3-oxidation state (In 3+ ) within In2O3 [44]. The multiple peaks of O 1s XPS spectra ( Figure 5C) were observed owing to different   Figure 5A). These results were supported by EDX and mapping results (Figures 3 and 4). Therefore, XPS spectra of In 3d are presented in Figure 5B, which shows the chemical states of indium (In) in the In 2 O 3 /RGO NCs. Hence, the two peaks were observed at 444 and 451.5 eV for In 3d 5/2 and In3d 3/2 , respectively [36,43]. Earlier studies reported that these peaks are distinctive properties of indium (In) in the +3-oxidation state (In 3+ ) within In 2 O 3 [44]. The multiple peaks of O 1s XPS spectra ( Figure 5C) were observed owing to different oxygen species, such as metal oxide (O 2− ) and adsorbed oxygen (O) [45]. The peak centered around 529.4 eV was assigned to the O 2− species in In 2 O 3 . Other peaks are located at higher binding energies, around 530-533 eV. These peaks are attributed to the presence of oxygen-containing functional groups on the RGO in the In 2 O 3 /RGO NCs, as reported in previous studies [46,47]. Similarly, the XPS spectra of C 1s ( Figure 5D) exhibit three peaks, which are assigned at 284.3, 285.9, and 288.4 eV to different carbon species, graphitic carbon (C=C/C-C), oxygenated carbon (C-O/C=O), and carboxyl groups (O-C=O), respectively [48]. XPS results reveal that the In 2 O 3 /RGO NCs were successfully prepared.

Raman Analysis
Raman spectroscopy is a powerful analytical technique that was applied to investigate the vibrational properties of synthesized samples. Figure 6a-c illustrates the Raman spectra of RGO, pure In 2 O 3 NPs, and In 2 O 3 /RGO NCs. It can be seen in Figure 6a that the Raman spectra of RGOs have two distinct peaks, which are the D-band (1350 cm −1 ) and G-band (1595 cm −1 ). Moreover, the D-band is associated with the presence of defects or disorders in the graphene structure, while the G-band corresponds to the E 2 g vibrational mode of sp 2 hybridized carbon atoms [49]. However, the ratio of the intensities of the D-band and G-band (I D /I G ) indicates the degree of disorder in the graphene structure [50]. We observed that the Raman spectra (Figure 6c) of In 2 O 3 NPs exhibit a sharp and intense peak at around 558 cm −1 , which corresponds to the Eg mode of In 2 O 3 [51]. An additional peak in the Raman spectra of In 2 O 3 NPs was assigned at 287 cm −1 due to the E 2 g mode [52]. Hence, the Raman spectra (Figure 6b) of In 2 O 3 /RGO NCs show a combination of the RGO and In 2 O 3 NPs. In comparison with pure In 2 O 3 NPs, the D-band and G-band peaks of RGO were still present in the spectra [40,53]. Importantly, these peaks were further associated with Raman spectra of In 2 O 3 NPs as supported by this study [16]. Obtained results show that the In 2 O 3 /RGO NCs were successfully synthesized due to the strong interaction between the RGO and In 2 O 3 NPs. oxygen species, such as metal oxide (O 2− ) and adsorbed oxygen (O) [45]. The peak centered around 529.4 eV was assigned to the O 2− species in In2O3. Other peaks are located at higher binding energies, around 530-533 eV. These peaks are attributed to the presence of oxygen-containing functional groups on the RGO in the In2O3/RGO NCs, as reported in previous studies [46,47]. Similarly, the XPS spectra of C 1s ( Figure 5D) exhibit three peaks, which are assigned at 284.3, 285.9, and 288.4 eV to different carbon species, graphitic carbon (C=C/C-C), oxygenated carbon (C-O/C=O), and carboxyl groups (O-C=O), respectively [48]. XPS results reveal that the In2O3/RGO NCs were successfully prepared.

Raman Analysis
Raman spectroscopy is a powerful analytical technique that was applied to investigate the vibrational properties of synthesized samples. Figure 6a-c illustrates the Raman spectra of RGO, pure In2O3 NPs, and In2O3/RGO NCs. It can be seen in Figure 6a that the Raman spectra of RGOs have two distinct peaks, which are the D-band (1350 cm −1 ) and Gband (1595 cm −1 ). Moreover, the D-band is associated with the presence of defects or disorders in the graphene structure, while the G-band corresponds to the E2g vibrational mode of sp 2 hybridized carbon atoms [49]. However, the ratio of the intensities of the Dband and G-band (ID/IG) indicates the degree of disorder in the graphene structure [50]. We observed that the Raman spectra (Figure 6c) of In2O3 NPs exhibit a sharp and intense peak at around 558 cm −1 , which corresponds to the Eg mode of In2O3 [51]. An additional peak in the Raman spectra of In2O3 NPs was assigned at 287 cm −1 due to the E2g mode [52]. Hence, the Raman spectra (Figure 6b) of In2O3/RGO NCs show a combination of the RGO and In2O3 NPs. In comparison with pure In2O3 NPs, the D-band and G-band peaks of RGO were still present in the spectra [40,53]. Importantly, these peaks were further associated with Raman spectra of In2O3 NPs as supported by this study [16]. Obtained results show that the In2O3/RGO NCs were successfully synthesized due to the strong interaction between the RGO and In2O3 NPs.

UV Analysis
Investigation of the optical absorption of prepared samples was further performed using UV-Vis spectroscopy. Figure 7A,B depict the peak absorption of pure In2O3 NPs and In2O3/RGO NCs. UV-Vis spectra of pure In2O3 NPs ( Figure 7A) exhibit a sharp absorption edge at 392 nm, while the absorption peaks ( Figure 7B) of In2O3 /RGO NCs were also associated at 405 nm. These values indicated that the absorption edge of In2O3 /RGO NCs is shifting to a higher wavelength compared to pure In2O3 NPs. Thus, the phenomena shows a reduction in the bandgap energy of the In2O3 /RGO due to the presence of RGO in pure In2O3 NPs as reported by these investigators [32,54]. As depicted in Table 1, the band gap energies of In2O3 NPs and In2O3/RGO NPs were 11.17 eV and 3.22 eV, respectively. Owing to the strong interaction between pure In2O3 and RGO nanosheet, the band gap energy increased with the dopant of RGO. UV-Vis results indicated that RGO doping

UV Analysis
Investigation of the optical absorption of prepared samples was further performed using UV-Vis spectroscopy. Figure 7A,B depict the peak absorption of pure In 2 O 3 NPs and In 2 O 3 /RGO NCs. UV-Vis spectra of pure In 2 O 3 NPs ( Figure 7A) exhibit a sharp absorption edge at 392 nm, while the absorption peaks ( Figure 7B) of In 2 O 3 /RGO NCs were also associated at 405 nm. These values indicated that the absorption edge of In 2 O 3 /RGO NCs is shifting to a higher wavelength compared to pure In 2 O 3 NPs. Thus, the phenomena shows a reduction in the bandgap energy of the In 2 O 3 /RGO due to the presence of RGO in pure In 2 O 3 NPs as reported by these investigators [32,54]. As depicted in Table 1

UV Analysis
Investigation of the optical absorption of prepared samples was further performed using UV-Vis spectroscopy. Figure 7A,B depict the peak absorption of pure In2O3 NPs and In2O3/RGO NCs. UV-Vis spectra of pure In2O3 NPs ( Figure 7A) exhibit a sharp absorption edge at 392 nm, while the absorption peaks ( Figure 7B) of In2O3 /RGO NCs were also associated at 405 nm. These values indicated that the absorption edge of In2O3 /RGO NCs is shifting to a higher wavelength compared to pure In2O3 NPs. Thus, the phenomena shows a reduction in the bandgap energy of the In2O3 /RGO due to the presence of RGO in pure In2O3 NPs as reported by these investigators [32,54]. As depicted in Table 1, the band gap energies of In2O3 NPs and In2O3/RGO NPs were 11.17 eV and 3.22 eV, respectively. Owing to the strong interaction between pure In2O3 and RGO nanosheet, the band gap energy increased with the dopant of RGO. UV-Vis results indicated that RGO doping plays a role in improving the optical properties of In2O3 for photocatalytic and biomedicine applications.

PL Analysis
Photoluminescence (PL) analysis was employed to ascertain the segregation of photogenerated electrons and holes within the synthesized samples. Figure 8 presents the room-

PL Analysis
Photoluminescence (PL) analysis was employed to ascertain the segregation of photogenerated electrons and holes within the synthesized samples. Figure 8 presents the room-temperature photoluminescence (PL) spectra of pure In 2 O 3 NPs and In 2 O 3 /RGO NCs. Excitation was achieved using a 320 nm wavelength. The PL spectra show an emission peak at 391.11 nm for all the prepared NPs as reported in a previous study [55]. After the dopant of the RGO sheet, the emission peak of In 2 O 33 /RGO NCs was highly decreased compared with pure In 2 O 3 NPs. It was noticed that the PL intensity of the In 2 O 3 /RGO NCs (indicated by the red line) was lower compared to pure In 2 O 3 NPs. This could be attributed to enhanced charge separation, lifespan of the electron-hole pair, and charge efficiency [56]. PL results indicate that the prepared In 2 O 3 /RGO NCs can be applied to enhance photocatalytic activity and biomedical applications. temperature photoluminescence (PL) spectra of pure In2O3 NPs and In2O3/RGO NCs. Excitation was achieved using a 320 nm wavelength. The PL spectra show an emission peak at 391.11 nm for all the prepared NPs as reported in a previous study [55]. After the dopant of the RGO sheet, the emission peak of In2O33/RGO NCs was highly decreased compared with pure In2O3 NPs. It was noticed that the PL intensity of the In2O3/RGO NCs (indicated by the red line) was lower compared to pure In2O3 NPs. This could be attributed to enhanced charge separation, lifespan of the electron-hole pair, and charge efficiency [56]. PL results indicate that the prepared In2O3/RGO NCs can be applied to enhance photocatalytic activity and biomedical applications.

Photocatalytic Performance
The photocatalytic performance of synthesized samples was assessed by the degradation of MB dye under UV light irradiation. Figure 9A-D shows the results of the photocatalytic pure In2O3 NPs and In2O3/RGO NCs under UV light irradiation by degradation of MB dye. As shown in Figure 9A, the In2O3/RGO NCs exhibited significantly higher photocatalytic activity than pure In2O3 NPs. Furthermore, the absorption peak ( Figure 9B) of

Photocatalytic Performance
The photocatalytic performance of synthesized samples was assessed by the degradation of MB dye under UV light irradiation. Figure 9A-D shows the results of the photocatalytic pure In 2 O 3 NPs and In 2 O 3 /RGO NCs under UV light irradiation by degradation of MB dye. As shown in Figure 9A, the In 2 O 3 /RGO NCs exhibited significantly higher photocatalytic activity than pure In 2 O 3 NPs. Furthermore, the absorption peak ( Figure 9B) of MB at 664 nm was gradually decreased through the degradation time (120 min) of In 2 O 3 /RGO NCs. The linear relationship between the natural logarithm of the ratio of the initial (ln(C 0 /C t )) and the degradation time (min) is shown in Figure 9C. The high linearity of the plot indicates that the photocatalytic degradation of MB of In 2 O 3 /RGO NCs follows a first-order kinetics reaction. However, the rate constant (K) values of pure In 2 O 3 NPs and In 2 O 3 /RGO NCs were 0.00248 min −1 and 0.01526 min −1 , respectively [32]. It can be seen in Figure 9D

Cytotoxicity and Compatibility Investigations
Different studies have examined the anticancer potential of graphene nanocomposites (NCs) based on metal oxides against various types of cancer cells [62][63][64]. Cytotoxicity and cytocompatibility of prepared samples at different concentrations against (HC116 and HepG2) as well as in normal PBMCs were illustrated in Figure 11A-C. As depicted in Figure 11A, the cell viability of the HC116 cell lines decreased with increasing concentrations of the prepared samples. Similarly, the cytotoxicity effects of both the prepared samples against the HepG2 cell line were increased with increasing concentrations. These Results show that the In2O3/RGO NCs have higher cytotoxicity toward HC116 and HepG2 cancer cells in comparison with pure In2O3 NPs. Significantly, Figure 11C shows the cytocompatibility of the prepared samples against normal human PBMCs. It is observed that the percentage of cell viability remained relatively constant across all concentrations of the prepared samples. The collected results suggest that the addition of RGO to pure In2O3 NPs enhances anticancer efficacy. IC50 values of synthesized samples are presented in Ta-

Cytotoxicity and Compatibility Investigations
Different studies have examined the anticancer potential of graphene nanocomposites (NCs) based on metal oxides against various types of cancer cells [62][63][64]. Cytotoxicity and cytocompatibility of prepared samples at different concentrations against (HC116 and HepG2) as well as in normal PBMCs were illustrated in Figure 11A-C. As depicted in Figure 11A, the cell viability of the HC116 cell lines decreased with increasing concentrations of the prepared samples. Similarly, the cytotoxicity effects of both the prepared samples against the HepG2 cell line were increased with increasing concentrations. These Results show that the In 2 O 3 /RGO NCs have higher cytotoxicity toward HC116 and HepG2 cancer cells in comparison with pure In 2 O 3 NPs. Significantly, Figure 11C shows the cytocompatibility of the prepared samples against normal human PBMCs. It is observed that the percentage of cell viability remained relatively constant across all concentrations of the prepared samples. The collected results suggest that the addition of RGO to pure In 2 O 3 NPs enhances anticancer efficacy. IC 50 values of synthesized samples are presented in Table 3.
city and cytocompatibility of prepared samples at different concentrations against (HC116 and HepG2) as well as in normal PBMCs were illustrated in Figure 11A-C. As depicted in Figure 11A, the cell viability of the HC116 cell lines decreased with increasing concentrations of the prepared samples. Similarly, the cytotoxicity effects of both the prepared samples against the HepG2 cell line were increased with increasing concentrations. These Results show that the In2O3/RGO NCs have higher cytotoxicity toward HC116 and HepG2 cancer cells in comparison with pure In2O3 NPs. Significantly, Figure 11C shows the cytocompatibility of the prepared samples against normal human PBMCs. It is observed that the percentage of cell viability remained relatively constant across all concentrations of the prepared samples. The collected results suggest that the addition of RGO to pure In2O3 NPs enhances anticancer efficacy. IC50 values of synthesized samples are presented in Table 3.

Synthesis of Pure In2O3 NPs and In2O3/RGO NCs
The preparation of pure In2O3 NPs and In2O3/RGO NCs were carried out via the microwave hydrothermal method [24]. A sample of 50 mg of RGO nanosheet was dissolved in 20 mL of deionized water with magnetic stirring to get an homogeneous GO suspension as the first solution. Similarly, the 0.5 g of In (NO3)3. xH2O was also dispersed in 40 mL of deionized water with magnetic stirring as a second solution. Subsequently, the first and

Synthesis of Pure In 2 O 3 NPs and In 2 O 3 /RGO NCs
The preparation of pure In 2 O 3 NPs and In 2 O 3 /RGO NCs were carried out via the microwave hydrothermal method [24]. A sample of 50 mg of RGO nanosheet was dissolved in 20 mL of deionized water with magnetic stirring to get an homogeneous GO suspension as the first solution. Similarly, the 0.5 g of In (NO 3 ) 3 . xH 2 O was also dispersed in 40 mL of deionized water with magnetic stirring as a second solution. Subsequently, the first and second solutions were mixed with magnetic stirring. Then, NaOH (1 M) and EG (5 mL) were added to the mixture under vigorous stirring for 2 h. The mixture solution was transferred to a Teflon-lined stainless-steel autoclave (100 mL). After that, the autoclave was sealed and subjected to microwave treatment in a microwave oven (2450 MHz) at 160 • C for 1 h. After the microwave hydrothermal reaction, the vessel was removed from the microwave reactor. After cooling to room temperature, the obtained precipitates were collected by centrifugation, washed with deionized water and ethanol, and dried at 60 • C for 12 h. The pure In 2 O 3 NPs were further synthesized by the same method but without adding RGO. The synthesis protocol for In 2 O 3 /RGO nanocomposites is depicted in Scheme 1.

Characterization
Measurements of the crystallinity and purity and crystal size of synthesized samples were carried out using X-ray diffractometer (XRD) analysis (PanAnalytic X'Pert Pro, Malvern Instruments, Malvern, UK). Transmission electron microscopy (TEM) (200 kV,2100F, JEOL, Inc., Tokyo, Japan) and scanning electron microscopy (SEM) (SEM, JSM-7600F, JEOL, Inc. Tokyo, Japan) (JSM-7600F, JEOL, Inc.) were further employed to assess the morphologies and the distribution of prepared samples. Energy dispersive X-ray spectroscopy (EDX) (SEM, JSM-7600F, JEOL, Inc. Tokyo, Japan) (JSM-7600F, JEOL, Inc.) was also used to confirm the presence of elements in synthesized samples. Furthermore, the chemical state and elemental composition of obtained samples were determined by X-ray photoelectron spectroscopy (XPS) (PHI-5300 ESCA PerkinElmer, Boston, MA, USA). Additionally, Raman spectroscopy was used to study the vibrational modes of the synthesized samples. The optical properties of synthesized samples were assayed using UV-Vis (Hitachi U-2600) and Photoluminescence (PL) (Hitachi F-4600) spectroscopy.

Photocatalytic Experiment
The degradation of MB dye solution under UV light irradiation (300 W xenon lamp) was carefully used to evaluate the photocatalytic properties of prepared samples. The 20 mg of pure In2O3 NPs and 10 mg/L of MB dye solution were added to a 250 mL beaker of

Characterization
Measurements of the crystallinity and purity and crystal size of synthesized samples were carried out using X-ray diffractometer (XRD) analysis (PanAnalytic X'Pert Pro, Malvern Instruments, Malvern, UK). Transmission electron microscopy (TEM) (200 kV, 2100F, JEOL, Inc., Tokyo, Japan) and scanning electron microscopy (SEM) (SEM, JSM-7600F, JEOL, Inc. Tokyo, Japan) (JSM-7600F, JEOL, Inc.) were further employed to assess the morphologies and the distribution of prepared samples. Energy dispersive X-ray spectroscopy (EDX) (SEM, JSM-7600F, JEOL, Inc. Tokyo, Japan) (JSM-7600F, JEOL, Inc.) was also used to confirm the presence of elements in synthesized samples. Furthermore, the chemical state and elemental composition of obtained samples were determined by X-ray photoelectron spectroscopy (XPS) (PHI-5300 ESCA PerkinElmer, Boston, MA, USA). Additionally, Raman spectroscopy was used to study the vibrational modes of the synthesized samples. The optical properties of synthesized samples were assayed using UV-Vis (Hitachi U-2600) and Photoluminescence (PL) (Hitachi F-4600) spectroscopy.

Photocatalytic Experiment
The degradation of MB dye solution under UV light irradiation (300 W xenon lamp) was carefully used to evaluate the photocatalytic properties of prepared samples. The 20 mg of pure In 2 O 3 NPs and 10 mg/L of MB dye solution were added to a 250 mL beaker of deionized water. Then, the solution suspension was further stirred in the dark for 30 min to achieve an adsorption-desorption equilibrium between the samples and the MB solution. Subsequently, this solution was irradiated under UV light irradiation with magnetic stirring. At 20 min intervals, 3 mL of the solution suspension was taken during the photocatalytic reaction. Then, the concentration of the photodegraded MB solution was further measured by a UV-Visible spectrophotometer after removing the photocatalyst of this solution. The photocatalytic actvity of the In 2 O 3 /RGO NCs was also evaluated under the same experimental conditions. The degradation efficiency of MB dye was calculated using the following formula of D (%) = [(C 0 − C t )/C t ] × 100. Where C 0 represents the dye concentration at the beginning, while C t refers to the dye concentration after a certain time 't' (measured in min). To test the stability, the catalysts were centrifuged, washed with deionized water and ethanol, and dried at 60 • C for 12 h. Hence, centrifuged catalysts were used several times after drying at 70 • C for 10 h.

Cytotoxicity Assessment
The cytotoxicity of synthesized In 2 O 3 NPs and In 2 O 3 /RGO NCs was further assessed using human colorectal (HCT116) and liver (HepG2) cancer cells by using the MTT assay. Importantly, the biocompatibility of prepared samples was tested agonist human normal peripheral blood mononuclear cells (PBMCs). Cells were cultured in Dulbecco's Modified Eagle's Medium (DMEM) containing 10% fetal bovine serum (FBS) and 1% penicillinstreptomycin at 37 • C in a humidified atmosphere of 5% CO 2 . Thus, cells were seeded in a 96-well plate at a density of 5 × 10 3 cells/well and incubated for 24 h. Then, the cells were treated with various concentrations (5-240 µg/mL) of pure In 2 O 3 NPs and In 2 O 3 /RGO NCs with incubation for 24 h. The cell viability was measured using absorbance at 570 nm using a microplate reader.

Statistical Analysis
The statistical analysis was performed using a one-way analysis of variance (ANOVA) followed by the multiple comparison test of Tukey. A value of p < 0.05 was considered statistically significant.

Conclusions
In the present study, we used a single-step microwave hydrothermal method for the fabrication of In 2 O 3 on the surface of RGO. The prepared samples have been analyzed using XRD, TEM, SEM, EDX, XPS, Raman spectroscopy, UV-Vis, and PL spectroscopy. XRD data show that the synthesized samples exhibited high crystallinity with reduced crystal size after RGO addition. TEM and SEM images showed that In 2 O 3 NPs were spherically shaped and uniformly embedded on RGO sheets. EDX and XPS analysis confirmed the elemental composition without impurities. The PL study suggests a hindrance in the recombination rate of electron-holes of In 2 O 3 /RGO NCs in comparison to pure In 2 O 3 NPs. Raman analysis further confirmed the successful fabrication of In 2 O 3 on the RGO surface. In the degradation experiment, it was observed that the In 2 O 3 /RGO NCs display better photocatalytic performance as compared to pure In 2 O 3 NPs. The biological data revealed that In 2 O 3 /RGO NCs have higher anticancer activity in human colorectal (HCT116) and liver (HepG2) cancer cells than those of In 2 O 3 NPs. Moreover, In 2 O 3 /RGO NCs demonstrated higher cytocompatibility with human normal peripheral blood mononuclear cells (PBMCs) compared to pure In 2 O 3 NPs. These results indicate that incorporating RGO enhances the photocatalytic and anticancer properties of In 2 O 3 NPs. This research emphasizes the promising capabilities of In 2 O 3 /RGO NCs as highly effective photocatalysts and therapeutic materials.