ABSTRACT
This study aims to explore how an effective cross-institutional Community of Practice (CoP) can be established to promote technology-enhanced language learning and teaching (TeLL&T) at tertiary level, as there is an urgent need for establishing such CoPs due to the large-scale implementation of technology-enhanced language learning and teaching in recent years. In this study, an action research design was adopted, and a five-stage procedure has been identified for the establishment of the CoP on TeLL&T: (1) Investigation of students' and teachers' needs in TeLL&T through surveys and interviews; (2) Identifying a critical mass to form the CoP; (3) Constructing the CoP website to provide a platform with rich TeLL&T resources; (4) University students and teachers sharing their good practices of TeLL&T through various means; (5) Evaluation of the CoP activities. Different evaluation surveys were conducted among university students and teachers to evaluate the effectiveness of the CoP activities. Findings of evaluation surveys suggest that the CoP activities were well received. This study also illustrated the challenges and solutions of creating and maintaining a substantial CoP on TeLL&T. It is hoped that the findings will shed some light on how to establish an effective CoP on TeLL&T at tertiary level.
ABSTRACT
Herein, we simply synthesized intrinsic fluorescent polydopamine nanoparticles (PDA NPs) in sodium hydroxide solution (NaOH, pH 11), and constructed a new fluorescence nanoplatform for the detection of alkaline phosphatase (ALP) using PDA NPs as an effective signal reporter. The nanoplatform was constructed by the combination of enzymatic hydrolysis of ALP to the substrate l-ascorbic acid-2-phosphate (AA2P) and the chemical redox reaction between l-ascorbic acid (AA) and mercury ion (Hg2+). The fluorescence of PDA NPs could be effectively quenched by Hg2+ through the coordination effect between Hg2+ and the functional groups on the surface of PDA NPs. However, the quenching effect was greatly inhibited by the addition of AA into the solution. Based on this point, the activity of ALP could be monitored by hydrolysis of the substrate AA2P to AA and the fluorescence output of PDA NPs. The nanoplatform exhibited high sensitivity and desirable selectivity for ALP detection. With a wide linear range of 0 to 18 U L-1, a detection limit of 0.4 U L-1 was achieved using the developed nanosensor. The proposed method could not only be used to screen the inhibitor of ALP but also be used to detect ALP activity in human serum samples successfully. Moreover, the strategy can easily be expanded to determining other kinds of enzymes participating in AA-generation reactions.
ABSTRACT
Herein, a novel fluorescence nanosensor using intrinsic fluorescent polydopamine nanoparticles (PDA NPs) as an effective signal reporter has been constructed for the simple, rapid and sequential detection of mercury ions (Hg2+) and l-ascorbic acid (AA) based on a coordination effect and redox reaction. The fluorescence of the PDA NPs could be specifically quenched by Hg2+ through intense coordination effects between the Hg2+ and the groups (catechol, amine, ketone and imine) on the surface of the PDA NPs. However, when AA and Hg2+ coexisted in solution, the fluorescence of the PDA NPs pronouncedly recovered via the redox reaction of Hg2+, with it being reduced to Hg0 by AA. The fluorescence quenching mechanism of Hg2+ towards the PDA NPs and the redox reaction between Hg2+ and AA were also fully investigated. The nanosensor exhibited high sensitivity and desirable selectivity for Hg2+ and AA detection. Moreover, the strategy was successfully explored in real samples (tap water, lake water and human serum samples) with satisfactory recoveries. The developed nanosensor provides new sights and good inspiration for Hg2+ and AA detection under real conditions.
