Eco-friendly intracellular biosynthesis of CdS quantum dots using Pseudomonas aeruginosa: Evaluation of antimicrobial effects and DNA cleavage activities

Abstract

Background: Intracellular biosynthesis of quantum dots (QDs) based on microorganisms offers a green alternative and eco-friendly for the production of nanocrystals with superior properties. This study focused on the production of intracellular CdS QDs by stimulating the detoxification metabolism of Pseudomonas aeruginosa. Methods: For this aim, Pseudomonas aeruginosa ATCC 27853 strain was incubated in a solution of 1mM cadmium sulphate (CdSO4) to manipulate the detoxification mechanism. The intracellularly formed Cd-based material was extracted, and its characterization was carried out by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and dynamic light scattering (DLS) analyses and absorption-emission spectra. Results: The obtained material showed absorption peaks at 385 nm and a luminescence peak at 411 nm, and the particle sizes were measured in the range 4.63-17.54 nm. It was determined that the material was sphere-shaped, with a cubic crystalline structure, including Cd and S elements. The agar disk diffusion method investigated the antibacterial and antifungal activities of CdS QDs against eleven bacterial (four Gram-positive and seven Gram-negative) and one fungal strain. It was revealed that the obtained material has antibacterial effects on both Gram-positive and Gram-negative bacteria. However, cleavage activity of CdS QDs on pBR322 DNA was not detected. Conclusion: As a result, it has been proposed that the stimulation of the detoxification mechanism can be an easy and effective way of producing green and cheap luminescent QDs or nanomaterial.