A new fluorescent probe for detecting lead ions (Pb2+) is reported in this work. Positively charged UCPs capped with ethylene imine polymer (PEI) and negatively charged AuNPs capped with 11-mercaptoundecanoic acid (MUA) were used as fluorescent donors and acceptors, respectively. The fluorescence quenching process was initiated by the electrostatic interaction between PEI–UCPs and MUA–AuNPs. Upon the addition of Pb2+, functionalized AuNPs were aggregated by an ion-templated chelation process, causing the departure of AuNPs from UCPs. As a result, the fluorescence of the donor was restored and the recovery was found to be proportional within the range of 0.5–10 μM to the concentration of Pb2+. The detection limit was found to be 20 nM. This method was easy to operate with satisfactory selectivity and remarkable sensitivity which would be meaningful in Pb2+-related detection.
To develop a more green and effective method for tetracycline (TC) removal, a hybrid material (conversion phosphors-TiO 2 , UCPs-TiO 2 ) was coupled with a biofilm to achieve enhanced removal of TC. The removal of TC by biofilm coupled with UCPs-TiO 2 under visible light reached 82%, which was 35% higher than that in treatment using only the biofilm. Extracellular polymeric substance (EPS) promoted the production of hydroxyl radicals by UCPs-TiO 2 , as the EPS acted as an electron transfer medium and accelerated the TC mineralization. Biofilm in the coupled system tolerated TC stress by regulating its antibiotic resistance genes (ARG) and superoxide dismutase (SOD), and allowed it to maintain stable and efficient removal of TC. This study documents a method to couple a hybrid material with microbial aggregates, creating a promising system for removing refractory organics, such as TC, from water. The study also offers insight into the mechanisms underlying TC removal by microbial aggregates combined with new functional materials.
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