Eco-Friendly and Systematic Study for Synthesis of La³⁺/α-Al₂O₃ Nanoparticles: Antibacterial Activity Against Pathogenic Microbial Strains

Figures & data

Figure 1 Data of factorial design as hydrothermal time, temperature, ultrasound irradiation power and interaction between these factors by the size (nm).

Figure 2 XRD patterns of the α-Al₂O₃ NPs and the as-synthesized La³⁺/α-Al₂O₃ NPs heating after calcination at 300°C for 3 hours.

Figure 3 The SEM image (A), TEM image (B) and electron dispersive spectroscopy (EDX) (C) as- synthesized La³⁺/α-Al₂O₃ NPs prepared via ultrasound assisted hydrothermal method.

Figure 4 Elemental mapping analysis of the as-synthesized La³⁺/α-Al₂O₃ NPs (A) and the UV-vis spectra of the as synthesized La³⁺/α-Al₂O₃ NPs in different conditions such as 10 hours (S1), 8 hours (S2), 6 hours (S3), and 4 hours (S4) at 200°C (B).

Figure 5 The FT-IR spectrum of the α-Al₂O₃ (A), La³⁺/α-Al₂O₃ nanocomposites as-synthesized after 300°C (B) and AFM images of the La³⁺/α-Al₂O₃ nanocomposites after annealing at 200°C for 6 hours (C).

Figure 6 The N₂ adsorption/desorption isotherm (A) and pore size distribution curve data of the La³⁺/α-Al₂O₃ nanocomposites (B).

Table 1 The Surface Features of the La³⁺/α-Al₂O₃ Nanocomposites as-synthesized after 300°C

BET area (m^2 g^–1)	Pore volume (cm^3 g^–1)	Pore diameter (nm)
37.879	0.359	22.679

Table 2 Antibacterial Activity of the La³⁺/α-Al₂O₃ Nanocomposites with MIC (μg/Ml) Method Against Selected Gram-Positive and Gramnegative Pathogenic Bacterial Strains

Concentration (µg/mL) Bacteria	64 µg/mL	32 µg/mL	16 µg/mL	8 µg/mL	4 µg/mL	2 µg/mL	1 µg/mL	0.5 µg/mL
E. coli PTCC 1330	-	-	-	-	-	-	-	-
K. pneumoniae PTCC 1053	-	-	-	-	-	-	-	-
S. marcescens PTCC1621	-	-	-	-	-	-	-	-
P. aeruginosa PTCC1074	-	-	-	-	-	-	-	-
S. aureus PTCC. 1112	-	-	-	-	-	-	-	+
M. luteus PTCC. 1110	-	-	-	-	+	+	+	+
B. subtilis PTCC. 1023	-	-	-	-	-	-	-	-
S. epidermidis PTCC 1114	-	-	-	-	-	-	-	-

Figure 7 Antibacterial activity of La³⁺/α-Al₂O₃ nanocomposites against 4 gram-negative and 3 gram-positive bacteria. Different serial dilutions were 64 (plate1), 32 (plate 2), 16 (plate 3), 8 (plate 4), 4 (plate 5), 2 (plate 6), 1 (plate 7) and 0.5 (plate 8) μg/mL of the La³⁺/α-Al₂O₃ nanocomposites which added to the Mueller-Hinton agar medium.

Scheme 1 Summary of experimental route for the synthesis of the La³⁺/α-Al₂O₃ NPs.