RESUMEN
Bacillus amyloliquefaciens containing intracellularly biosynthesized cadmium selenide (CdSe) quantum dots (QDs) was used as a fluorescent bioprobe. Several parameters in the QD biosynthesis process were systematically optimized. The optimized protocol for producing high-quality CdSe QDs in B. amyloliquefaciens features mild synthetic conditions, good reproducibility, short reaction time and high yield. This process shows promise for the mass production of QDs by bacterial matrices. The resultant fluorescent B. amyloliquefaciens containing intracellular CdSe QDs was used as a bioprobe for the simple detection of copper (II) ions in blood plasma. The selective permeability of the bacterial cell membrane along with the protection provided by a protein envelope on the QD surface prevented interference by other components of blood plasma, resulting in the accurate determination of Cu2+. Using the copper addition method, the content of Cu2+ in human blood plasma samples was determined to be 15.6-18.5 µmol/L, consistent with atomic absorption spectroscopy results. The technique developed here shows potential for the simple determination of Cu2+ in plasma with excellent selectivity and good sensitivity.
Asunto(s)
Bacillus amyloliquefaciens/metabolismo , Compuestos de Cadmio/química , Cobre/sangre , Colorantes Fluorescentes/química , Puntos Cuánticos , Compuestos de Selenio/química , Adulto , HumanosRESUMEN
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.
Asunto(s)
Bacillus licheniformis/metabolismo , Compuestos de Cadmio , Cobre/análisis , Puntos Cuánticos/metabolismo , Puntos Cuánticos/microbiología , Compuestos de Selenio , Agua/análisis , Colorantes Fluorescentes/química , Límite de Detección , Puntos Cuánticos/ultraestructura , Espectrometría de Fluorescencia , Contaminantes Químicos del Agua/análisisRESUMEN
In the paper, a green and efficient biosynthetical technique was reported for preparing cadmium sulfide (CdS) quantum dots, in which Escherichia coli (E. coli) was chosen as a biomatrix. Fluorescence emission spectra and fluorescent microscopic photographs revealed that as-produced CdS quantum dots had an optimum fluorescence emission peak located at 470nm and emitted a blue-green fluorescence under ultraviolet excitation. After extracted from bacterial cells and located the nanocrystals' foci in vivo, the CdS quantum dots showed a uniform size distribution by transmission electron microscope. Through the systematical investigation of the biosynthetic conditions, including culture medium replacement, input time point of cadmium source, working concentrations of raw inorganic ions, and co-cultured time spans of bacteria and metal ions in the bio-manufacture, the results revealed that CdS quantum dots with the strongest fluorescence emission were successfully prepared when E. coli cells were in stationary phase, with the replacement of culture medium and following the incubation with 1.0×10-3mol/L cadmium source for 2 days. Results of antimicrobial susceptibility testing indicated that the sensitivities to eight types of antibiotics of E. coli were barely changed before and after CdS quantum dots were prepared in the mild temperature environment, though a slight fall of antibiotic resistance could be observed, suggesting hinted the proposed technique of producing quantum dots is a promising environmentally low-risk protocol.