Extracellular polymeric substances (EPS) of microbial sludge play a crucial role in removal of organic micropollutants during biological wastewater treatment. In this study, we examined ciprofloxacin (CIP) removal in three parallel bench-scale reactors using aerobic sludge (AS), anaerobic sludge (AnS), and sulfate-reducing bacteria (SRB) sludge. The results showed that the SRB sludge had the highest specific CIP removal rate via adsorption and biodegradation. CIP removal by EPS accounted up to 35. 6 ± 1.4%, 23.7 ± 0.6%, and 25.5 ± 0.4% of total removal in AS, AnS, and SRB sludge systems, respectively, at influent CIP concentration of 1000 μg/L, which implied that EPS played a critical role in CIP removal. The binding mechanism of EPS on CIP adsorption in three sludge systems were further investigated using a series of batch tests. The results suggested that EPS of SRB sludge possessed stronger hydrophobicity (proteins/polysaccharides (PN/PS) ratio), higher availability of adsorption sites (binding sites ( n)), and higher binding strength (binding constant ( K)) between EPS and CIP compared to those of AS and AnS. The findings of this study provide an insight into the role of EPS in biological process for treating CIP-laden wastewaters.

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A novel, sensitive, nonenzymatic amperometric sensor for the reliable detection of extracellular H 2 O 2 released from living cells was fabricated based on Fe 3 O 4 /reduced graphene oxide (Fe 3 O 4 /rGO) nanocomposites, which were prepared using a simple and cost-effective one-pot approach. Electrochemical performances of the Fe 3 O 4 /rGO nanocomposites modified glassy carbon electrode (GCE) were studied. The results demonstrated that this H 2 O 2 sensor exhibited excellent electrocatalytic performance towards the reduction of H 2 O 2 at a potential of À0.3 V in the wide linear concentration range from 0.001 to 20 mM with a high sensitivity of 387.6 mA mM À1 cm À2 and a detection limit as low as 0.17 mM (S/N ¼ 3), which was lower than certain enzymes and noble metal nanomaterials-based biosensors. Moreover, good anti-interference property, reproducibility, and long-term stability of the enzymeless sensor were achieved. Because of these remarkable analytical advantages, a novel, effective approach for the detection of extracellular H 2 O 2 released from HeLa cells stimulated by CdTe quantum dots (QDs) was established by the constructed sensor. Since H 2 O 2 is a byproduct of several oxidative biological reactions, this work could be applied to study the downstream biological effects of various stimuli in pathophysiology, and may expand the application of Fe 3 O 4 -based nanomaterials in the field of electrochemical sensing and bioanalysis.

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A sensitive fluorescence turn-on biosensing platform for protein kinase activity assay has been developed based on fluorescence resonance energy transfer (FRET) between a fluorophore labeled peptide and a water soluble cationic conjugated polymer (CCP). The CCP-based assay is based on the electrostatic interaction between the peptide and the CCP. The FRET efficiency will change with the changing charges around the peptide after phosphorylation. The feasibility of this method has been demonstrated by sensitive measurement of the activity of cAMP-dependent protein kinase (PKA) with a low detection limit (0.3 mU μL(-1)). Based on its simple mechanism, this assay is also sensitive and robust enough to be applied to the evaluation of PKA inhibitor H-89. The IC50 value, the half maximal inhibitory concentration, was 40 nM. Furthermore, our method has excellent selectivity. CCP-based assay is sensitive, versatile, cost-effective and easy to operate, so, this method is a promising candidate for kinase activity assay and inhibitor screening.

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An easily-made Annexin-V modified quartz crystal microbalance (QCM) sensor was constructed for the quantitative detection of early stage apoptosis for the first time, achieving the goals of specific capture and sensitive detection of target cells in one step without the need for cell labelling.