Synthesis of CdSe and CdSe:Ga nanostructures for antibacterial application

In this paper, the preparation of CdSe and CdSe:Ga nanoparticles using two methods: thermal evaporation and pulse laser ablation has been reported. Their structural properties were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). As confirmed by the XRD curves, CdSe and CdSe:Ga nanoparticles exhibited polycrystalline and wurtzite hexagonal structures with orientation planes of (100) (101) (102) (110) and (112). Also, a homogeneous distribution of nano-rod, flower-like, cylindrical, hexagonal and both nano-rod and hexagonal shapes with different diameters was seen by FESEM images. The band gaps of CdSe and CdSe:Ga (without annealed and annealed at temperatures of 150 (6 h) and 500℃ (1 h)) were found to be 1.72, 1.7, 1.69 and 1.64 eV, respectively. The antibacterial activity could be increased by annealing CdSe:Ga nanoparticles at 150℃ for 6 h in Gram-positive bacteria (Bacillus subtilis), whereas it is decreased in Gram-negative bacteria (Enterobacter cloacae). Alternatively, annealing CdSe:Ga at 500℃ for 1 h led to an increase in the antibacterial activity in both Gram-positive and Gram-negative bacteria. It is concluded that the antibacterial activity is highly dependent on the type of bacteria, material, preparation conditions and the used methods. (author)