Fluorescent CdSe QDs containing Bacillus licheniformis bioprobes for Copper (II) detection in water

Quantum dots (QDs) are semiconductor nanoparticles (NPs) that offer valuable functionality for cellular labeling, drug delivery, solar cells and quantum computation. In this study, we reported that CdSe QDs could be bio-synthesized in Bacillus licheniformis. After optimization, the obtained CdSe QDs exhibited a uniform particle size of 3.71±0.04nm with a maximum fluorescence emission wavelength at 550nm and the synthetical positive ratio can reach up to 87%. Spectral properties, constitution, particle sizes and crystalline phases of the CdSe QDs were systematically and integrally investigated. The CdSe QD-containing Bacillus licheniformis cells were further used as whole fluorescent bio-probes to detect copper (II) (Cu²⁺) in water, which demonstrated a low limit of detection (0.91μM). The assay also showed a good selectivity for Cu²⁺ over other ions including Al³⁺, Cd²⁺, Mg²⁺, K⁺, Na⁺, NH₄⁺, Zn²⁺, CH₃COO⁺, Pb²⁺ and I^-. Our study suggests the fluorescent CdSe QDs-containing Bacillus licheniformis bio-probes as a promising approach for detection of Cu²⁺ in complex solution environment.