Jin Yuting,Yan Rongfang,Wang Shuo,Wang Xianghong,Zhang Xuemei,Tang Yiwei
A novel fluorescence platform was fabricated for enrofloxacin determination by using cDNA-modified dipeptide fluorescence nanoparticles (FDNP-cDNA) and aptamer-modified magnetic Fe 3 O 4 nanoparticles (Fe 3 O 4 -Apt). The FDNP were prepared via tryptophan-phenylalanine self-assembling. When magnetic Fe 3 O 4 -Apt incubated with standard solution or sample extracts, the target enrofloxacin was selectively captured by the aptamer on the surface of the Fe 3 O 4 nanoparticles. After removing interference by washing with phosphate-buffered saline, the FDNP-cDNA was added, which can bind to the aptamer on the surface of the Fe 3 O 4 nanoparticles not occupied by the analyte. The higher the concentration of the target enrofloxacin in the standard or sample solution is, the less the FDNP-cDNA can be bound with the Fe 3 O 4 nanoparticles, and the more the FDNP-cDNA can be observed in the supernatant. Fluorescence intensity (E x /E m = 310/380 nm) increased linearly in the enrofloxacin concentration range 0.70 to 10.0 ng/mL with a detection limit of 0.26 ng/mL (S/N = 3). Good recoveries (88.17–99.30%) were obtained in spiked lake water, chicken, and eel samples with relative standard deviation of 2.7–6.2% ( n = 3). Graphical abstract
The performance of Fe 3 O 4 /attapulgite (APT) nanoparticles in Pb(II) adsorption from aqueous solutions could be improved by modifying the particles with aminopropyltriethoxysilane (APTS) and then combining with chitosan (CS) into beads. After preparing the APTS-Fe 3 O 4 /APT@CS beads, their surface morphology and crystal phases were analyzed by Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The magnetic properties of APTS-Fe 3 O 4 /APT@CS were studied by a vibrating sample magnetometer, while their heat resistance and stability were characterized by thermal weight analysis. A recycling test and comparison of adsorption capacities were also carried out. The adsorption capacity of Fe 3 O 4 /APT was improved by the modification with APTS and CS. The adsorption process conforms to the pseudo-second-order kinetic and Langmuir adsorption isotherm models. The adsorption of Pb(II) reaches a maximum of 625.34 mg/g, which compares favorably with other reported adsorbents. The results show that APTS-Fe 3 O 4 /APT@CS is a promising hybrid adsorbent for effective removal of Pb(II) from water.
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