Click chemistry in the design of AIEgens for biosensing and bioimaging

The development of rapid,selective,and sensitivefluorescent sensors is essential for visualizing and quantifying biological molecules and processes in vitro,ex vitro,and in vivo,which is important for not only fundamental biological studies but the accurate diagnosis of diseases.The emergingfield of activity-based sensing(ABS),a sensing method that utilizes molecular reactivity for analyte detection possesses many advantages including high specificity,sensitivity and accuracy.The aggrega-tion caused quenching phenomenon which occurs in most conventionalfluorophores results in reduced labeling efficiency of the target analytes and low photobleaching resistance,therefore limiting the applications of the ABS strategy.In contrast,aggre-gation induced emission(AIE)active luminogens(AIEgens)provide exceptional molecular frameworks for ABS.Of the many reaction classes utilized in the AIEgen ABS approach,click chemistry has become increasing popular.In this review,the sensing concepts of the ABS approach with AIEgens and the principles of click chemistry are discussed,followed by a systematic summary of the application of specific click chemistry reactions in AIEgen ABS protocols for the detection of an array of target analytes.Furthermore,the utility of click chemistry in the construction of AIEgens for bioimaging will also be showcased throughout the review.

The effect of tailing lipidation on the bioactivity of antimicrobial peptides and their aggregation tendency Special Issue:Emerging Investigators

Antimicrobial peptides(AMPs)are potentially powerful alternatives to conven-tional antibiotics in combating multidrug resistance,given their broad spectrum of activity.They mainly interact with cell membranes through surface electrostatic potentials and the formation of secondary structures,resulting in permeability and destruction of target microorganism membranes.Our earlier work showed that two leading AMPs,MSI-78(4–20)and pardaxin(1–22),had potent antimicrobial activ-ity against a range of bacteria.It is known that the attachment of moderate-length lipid carbon chains to cationic peptides can further improve the functionality of these peptides through enhanced interactions with the membrane lipid bilayer,inducing membrane curvature,destabilization,and potential leakage.Thus,in this work,we aimed to investigate the antimicrobial activity,oligomerization propensity,and lipid-membrane binding interactions of a range of N-terminal lipidated analogs of MSI-78(4–20)and pardaxin(1–22).Molecular modeling results suggest that aggregation of the N-lipidated AMPs may impart greater structural stability to the peptides in solu-tion and a greater depth of lipid bilayer insertion for the N-lipidated AMPs over the parental peptide.Our experimental and computationalfindings provide insights into how N-terminal lipidation of AMPs may alter their conformations,with subsequent effects on their functional properties in regard to their self-aggregation behavior,membrane interactions,and antimicrobial activity.

Production and emission of phosphine gas from wetland ecosystems

Phosphine is a part of an atmospheric link of phosphorus cycle on earth, which could be an important pathway for phosphorus transport in environment.Wetland ecosystems are important locations for global biogeochemical phosphorus cycle.In this study, production and emission fluxes of free phosphine from four wetlands types in southern China were observed in different seasons.The results showed that the concentration of phosphine liberated from wetlands was at pg/m3-ng/m3 level.The emission concentrations of different wetlands followed the sequence:paddy field(51.83 ± 3.06) ng/m3 marsh(46.54 ± 20.55) ng/m3 > lake(37.05 ± 22.74) ng/m3 coastal wetland(1.71 ± 0.73) ng/m3, the positive phosphine emission flux occurred in rice paddy field(6.67 ± 5.18) ng/(m2·hr) and marsh(6.23 ± 26.9) ng/(m2·hr), while a negative phosphine flux of(-13.11 ± 35.04) ng/(m2·hr) was observed on the water-air interface of Lake Taihu, suggesting that paddy field and marsh may be important sources for phosphine gas in atmosphere, while lake may be a sink of atmospheric phosphine gas during the sampling period.Atmospheric phosphine levels and emission flux from Yancheng marsh and rice paddy field varied in different seasons and vegetational zones.Both diffusion resistance in aqueous phase and temperature were dominating factors for the production and transportation of phosphine to atmosphere.

Biothiol-specific fluorescent probes with aggregation-induced emission characteristics

Biothiols are important species in physiological processes such as regulating protein structures, redox homeostasis and cell signalling. Alternation in the biothiol levels is associated with various pathological processes, therefore non-invasive fluorescent probes with high specificity to biothiols are highly desirable research utilities. Meanwhile, fluorescent probes with aggregationinduced emission properties(AIEgens) possess unique photophysical properties that allow modulation of the sensing process through controlling the aggregation-disaggregation or the intramolecular rotational motions of the fluorophores. Herein we review the recent progress in the development of biothiol-specific AIEgens. In particular, the molecular design principles to target different types of biothiols and the corresponding sensing mechanisms are discussed, along with the potential of the future design and development of multi-functional bioprobes.

Effects of La^(3+),Ce^(3+) on nitrogen removal in sequencing batch reactor

Batch experiments were conducted to study the short-term biological effects of rare earth ions(La^(3+),Ce^(3+))and their mixture on the nitrogen removal in a sequencing batch reactor(SBR).The data showed that higher NH4+–N removal rate,total inorganic nitrogen removal efficiency,and denitrification efficiency were achieved at lower concentrations of rare earth elements(REEs)(<1 mg/L).In the first hour of the aeration stage of SBR,the presence of REEs increased the total inorganic nitrogen removal efficiency and NH4+–N removal effi-ciency by 15.7%and 10%–15%,respectively.When the concentrations of REEs were higher than 1 mg/L,the total inorganic nitrogen removal efficiency decreased,and nitrate was found to accumulate in the effluent.When the concentrations of REEs was up to 50.0 mg/L,the total inorganic nitrogen removal efficiency was less than 30%of the control efficiency with a high level of nitrate.Lower concentrations of REEs were found to accelerate the nitrogen conversion and removal in SBR.