INTRODUCTION 
Because of its use in technology and science to engineer novel materials at the nanoscale level, nanotechnology is quickly emerging field [1]. In the case when put to comparison with the bulk forms with comparable chemical compositions, NPs have distinct chemical characteristics [2]. In the case when put to comparison with organic compounds, metal oxide NPs have demonstrated superior selectivity, stability, durability, and reduced toxicity [3]. Furthermore, the variations in these particles’ fundamental chemical and physical characteristics are caused by their size. Diagnostics, catalysis, water treatment, medication delivery, semiconductors, cosmetics, solid oxide fuels, and sensing are just a few of the impressive uses for such particles [4,5]. Aluminum oxide NPs could be utilized as absorbent in heterogeneous catalysis, as abrasive material, as reinforcements of metal-matrix composites, and as a biomaterial [6, 8]. They also have significant uses in the ceramic industry [7]. The number of microbes resistant to commonly utilized antibiotics has rapidly increased recently [9]. The contact surface area will rise by 109 nm when the size of particles is reduced from about 10µm to 10nm. Because of their high surface area to volume ratio as well as distinct physical and chemical properties, Nano-scale materials emerged as possible antimicrobial agents in the context [10]. It is anticipated that such a wide contact surface will increase the degree of bacterial eradication [11]. The biological activity of particle is possibly to be altered by reactive groups on its surface. Thus, with regard to microbial toxicity problems, modifications to metal oxide NPs type as well as surface chemistry are crucial [12]. Over a broad temperature range, alumina NPs exhibit thermodynamic stability. With alumina ions occupying 2/3 regarding octahedral positions in lattice and oxygen atoms that adopt hexagonal close packing, they resemble corundum [13]. To the best of our knowledge, little substantial study has been done on alumina NPs antibacterial qualities. Therefore, an effort was made to look into the minimal inhibitory concentration as well as antibacterial activity regarding Al2O3 NPs generated using co-precipitation approach.

MATERIALS AND METHODS 
Synthesis of alumina nanoparticles
Alumina nanoparticles were synthesized via the co-precipitation method using aluminum sulfate and sodium hydroxide as precursors. A 0.1 M aluminum sulfate solution was prepared by dissolving the required amount in distilled water under continuous magnetic stirring for 1 h. Subsequently, 0.2 M sodium hydroxide solution was added dropwise under constant stirring until a white gelatinous precipitate formed. The suspension was allowed to age overnight, after which the supernatant was carefully decanted. The precipitate was repeatedly washed with distilled water to remove residual ions and then dried at 80°C overnight. Finally, the dried precipitate was calcined at an appropriate temperature to obtain crystalline alumina (Al₂O₃) nanoparticles as seen in Fig. 1.

Bacterial Samples Preparation
In this research, produced by researchers in Baghdad, types of bacteria Staphylococcus aureus (Gram positive), obtained from the Contaminated Bacteria Laboratory, Ministry of Science and Technology, Baghdad, Iraq. Using a sterile loop, one colony of each of the mentioned bacteria was inoculated into 10 ml of Nutritional Broth and incubated overnight (37°C). After that, samples were then centrifuged for 5 minutes at 6000 RPM to form two types of bacterial solutions Streptococcus (Gram +) at 1 –10×8 cfu/ml .After the supernatants were removed, the cells were resuspended in 500 μL of phosphate buffered saline (PBS) and then spun down three times to ensure all media and debris have been eliminated from the cells [14]. After removing the supernatant from the last wash, the cells were resuspended in 50 μL of PBS and pipetted to mix and ensure equal distribution of cells prior to placing them on the substrate. As seen in Fig. 2 schematic illustration of bacterial suspension preparation for antibacterial activity assay.

RESULTS AND DISCUSSION 
X-ray diffraction result for Nano aluminum
In Fig. 3 Peaks located at approximately 38.5°, 44.7°, 65.1°, and 78.2° (2θ). These peaks are indexed to the (111), (200), (220), and (311) crystallographic planes, respectively, confirming the face-centered cubic (FCC) crystal structure of aluminum. The diffraction pattern is in good agreement with the standard ICDD PDF card No. 04-0787 for metallic aluminum. The high intensity and narrow peak widths indicate that the sample possesses good crystallinity and a well-ordered crystal lattice. Furthermore, no additional diffraction peaks corresponding to impurity phases or crystalline aluminum oxides are observed within the measured 2θ range, suggesting that the sample is predominantly composed of crystalline aluminum. The strongest diffraction peak appears at approximately 38.5°, corresponding to the (111) plane, which is the characteristic preferred reflection of FCC aluminum, while the remaining peaks exhibit the expected relative intensities, further confirming the phase purity and crystalline nature of the material. The results closely match the analyzed cell parameters, a = 0.5681, b = 0.2890, and c = 1.1776 nm. [15-16].

TEM Analysis of Aluminum Nanoparticles
The TEM image of the aluminum sample reveals the presence of agglomerated nanoparticles with irregular to nearly spherical morphology. The particles are clustered together, forming larger aggregates, which is commonly attributed to the high surface energy of nanosized aluminum particles. Although individual particles can be distinguished in some regions, the strong agglomeration makes precise particle size determination difficult from this image alone. No rod-like or plate-like structures are observed, indicating that the particles predominantly exhibit a quasi-spherical morphology. The observed contrast is consistent with crystalline metallic particles distributed in aggregated domains. These TEM observations in Fig. 4 are in good agreement with the XRD results, which exhibited sharp diffraction peaks at 2θ values of approximately 38.5°, 44.7°, 65.1°, and 78.2°, corresponding to the (111), (200), (220), and (311) planes of face-centered cubic (FCC) aluminum (ICDD PDF No. 04-0787). The sharp diffraction peaks confirm the crystalline nature of the aluminum particles observed in the TEM image, while the absence of additional diffraction peaks in the XRD pattern supports the predominance of a single crystalline aluminum phase. Therefore, the combined TEM and XRD analyses indicate that the sample consists of crystalline aluminum nanoparticles with an aggregated morphology [17-19].

The UV–Vis absorption spectrum of the synthesized alumina nanoparticles
The UV–Vis absorption spectrum of the synthesized alumina nanoparticles exhibits strong absorption in the ultraviolet region, with the highest absorption intensity observed at wavelengths below approximately 220 nm. A sharp decrease in absorbance is observed as the wavelength increases, followed by a nearly constant and very low absorption throughout the visible region (300–1100 nm) Fig. 4. This optical behavior is characteristic of alumina, reflecting its wide band gap and high transparency in the visible range. The absence of significant absorption peaks in the visible region indicates that no detectable impurity-related electronic transitions are present. These results Fig. 5 are consistent with the XRD analysis, which confirmed the formation of crystalline Al₂O₃ without detectable secondary crystalline phases, suggesting that the synthesized nanoparticles possess high structural purity and suitable optical properties for ultraviolet and optoelectronic applications [20].

Antibacterial activity of the Al Nano powder
The antibacterial activity of nanomaterial against Staphylococcus aureus as seen in Fig. 6 was evaluated using the agar diffusion method. As shown in the Fig. 6, the control (A) exhibited little or no inhibition zone, indicating the absence of antibacterial activity. The treated samples produced concentration-dependent inhibition zones. The lowest concentration (12.5%, B) showed a distinct inhibition zone, while the 25% concentration (C) exhibited moderate antibacterial activity. The 50% concentration (D) produced a larger inhibition zone than C, indicating enhanced antibacterial effectiveness. The highest concentration (100%, E) displayed the largest inhibition zone, demonstrating the strongest antibacterial activity against S. aureus. These findings suggest that the antibacterial efficacy of nanomaterial increased with increasing concentration, reflecting a dose-dependent inhibitory effect on bacterial growth. [21-22].

CONCLUSION 
Aluminum oxide nanoparticles were successfully synthesized using the co-precipitation method with aluminum sulfate and sodium hydroxide as precursors. XRD analysis confirmed the formation of crystalline Al₂O₃ nanoparticles, while TEM images demonstrated the nanoscale particle morphology with slight agglomeration. The antibacterial activity assay against Staphylococcus aureus revealed a concentration-dependent inhibitory effect, with the highest concentration (100%) exhibiting the largest inhibition zone. The results demonstrate that the synthesized Al₂O₃ nanoparticles possess effective antibacterial activity against Gram-positive bacteria and highlight their potential for biomedical and antimicrobial applications. Further studies are recommended to evaluate their biocompatibility, cytotoxicity, and antibacterial performance against a broader range of pathogenic microorganisms.

CONFLICT OF INTEREST
The authors declare that there is no conflict of interests regarding the publication of this manuscript.