Fluorescence resonance energy transfer (FRET) that consists of quantum dot as donors and organic fluorophore dyes as acceptors has been a very important method to detect biomolecules such as nucleic acids. In this work, we established a new FRET detection system of Bifidobacterium species-specific 16S rDNA using QD—ROX FRET bioprobe, in which 525 nm QD-DNA conjugation consisted of the carboxyl-modified QD and the amino-modified DNA in the presence of EDC. Both ROX-DNA and the conjugation above could hybridize with the target DNA after forming the QD—ROX bioprobe. When the hybridization made the distance between the QD and ROX to meet FRET effect needed, 525 nm QD fluorescence intensity decreased and ROX fluorescence intensity increased. In the control, there was no notable change of fluorescence intensities without target DNA. It is very clear that the change of the QD and ROX fluorescence intensities provide the good base and guaranty for this rapid and simple detection system.

The main goal of this study was to exploit low-cost and efficient sorbents for the removal and recovery of Cr (VI) in wastewater. Three supports of sawdust, polyurethane and alginate were applied to immobilize living and dead R. cohnii cells, respectively. There was a distinct increase in the Cr (VI) removal efficiency before and after the HCl-pretreatment. Langmuir adsorption isotherm model was well used to describe the distribution of Cr (VI) between the liquid and solid phases in batch studies. The values of q0 predicted by Thomas model were near to experimental ones in the experiments of packed column. The breakthrough curves calculated with this model were consistent well with experimental ones at a largely extent. Desorption, regeneration and reuse of the packed column were studied. After 5 cycles, adsorption capacity was still kept at higher level, reaching to 91.4, 87.9, 91.4 and 93.3 mg/l contrasted with the first cycle (94.1, 90.4, 94.8 and 98.5 mg/l) and the desorption efficiency were 85.0%, 96.2%, 93.4% and 91.4% compared with the first cycle (87.6%, 95.4%, 96.7% and 94.3%), corresponding to living cells immobilized with sawdust, polyurethane, and dead cells immobilized with polyurethane and alginate, respectively. The results indicated that the packed columns with the immobilized living and dead R. cohnii cells were the better option to adsorb, desorb and recover Cr (VI) from wastewater.

The goal of this study was to develop an applied technique for the removal and recovery of heavy metal in wastewater. It is novel that the Cr (VI) could be adsorbed and recovered by bio-functional magnetic beads. Furthermore, the magnetic separation technology would make their separation more convenient. The beads were constituted by the powder of Rhizopus cohnii and Fe3O4 particles coated with alginate and polyvinyl alcohol (PVA). The parameters effecting Cr (VI) removal were obtained: the optimum pH 1.0 and optimum temperature 28 C. The biosorption took place mainly in form of Cr (VI) and R. cohnii biomass played a key role in Cr (VI) adsorption. The model of Langmuir isotherm and Lagergren could be better used to fit the sorption process and kinetics, respectively. The beads still maintained predominant characteristics of adsorption, recovery and magnetism after five cycles for adsorption-desorption. The mechanism of adsorption was gained by Fourier transform infrared spectroscopy (FTIR), raman spectroscopy (RS) and scanning electron microscopy (SEM). The groups of-NHþ3,-NHþ2-, and NH- played an important role in the Cr (VI) adsorption. Consequently, the beads exhibited the superior performances in Cr (VI) cleanup, separation and recovery and the perspective potential in application. 2008 Elsevier Ltd. All rights reserved.

Fluorescence resonance energy transfer (FRET) between a quantum dot as donor and an organic fluorophore as acceptor has been widely used for detection of nucleic acids and proteins. In this paper, we developed a new method, characterized by 605-nm quantum dot (605QD) fluorescence intensity increase and corresponding Cy5 fluorescence intensity decrease, to detect adenosine triphosphate (ATP). The new method involved the use of three different oligonucleotides: 3′-biotin-modified DNA that binds to streptavidin-conjugated 605QD; 3′-Cy5- labelled DNA; and a capture DNA consisting of an ATP aptamer and a sequence which could hybridize with both 3′-biotin-modified DNA and 3′-Cy5-labelled DNA. In the absence of the target ATP, the capture DNA binds to 3′- biotin-modified DNA and 3′-Cy5-labelled DNA, bringing quantum dot and Cy5 into close proximity for greater FRET efficiency. When ATP is introduced, the release of the 3′- Cy5-labelled DNA from the hybridization complex took place, triggering 605QD fluorescence intensity increase and corresponding Cy5 fluorescence intensity decrease. Taken together, the virtue of FRET pair 605QD/Cy5 and the property of aptamer-specific conformation change caused by aptamer-ATP interaction, combined with the fluorescence intensity change of both 605QD and Cy5, provide prerequisites for simple and convenient ATP detection.

研究固定化黄孢原毛平革菌对水溶液中2，4-二氯酚（2，4-DCP）的降解效果，探讨固定化黄孢原毛平革菌处理水溶液中氯酚类污染物的可行性。结果表明，采用固定化方法处理的白腐真菌，其产酶稳定性及酶活均比游离态白腐真菌有显著提高。2，4-DCP降解效果受固定化孢子接种量、pH值、摇床转速、2，4-DCP的初始浓度和表面活性剂浓度的影响。当pH为4.5，摇床转速180r/min，培养基含有1%的Tween80，2，4-DCP初始浓度为40mg/L时，加入10mL固定化白腐真菌孢子，2，4-DCP去除效果最好。