Fabrication of a hierarchical nanoreactor based on COFs for cascade enzyme catalysis.

A hierarchical nanoreactor based on covalent organic frameworks (COFs) was fabricated using polystyrene spheres (PSs) as a template. When applied in cascade catalysis, the nanoreactor significantly improved the catalytic activity of internal enzymes, and showed protection for the enzyme in harsh environments. Moreover, glucose can be sensitively detected (detection sensitivity: 10 µM) by the nanoreactor.

Mechanisms and application of the IAST-EBC model for predicting 2-MIB adsorption by PAC in authentic raw waters: Correlation between NOM competitiveness and water quality parameters.

Natural organic matter (NOM) exerts negative impacts on 2-methylisoborneol (2-MIB) removal by powdered activated carbon (PAC), thus adding to the difficulty in accurate PAC dose prediction. Our study investigated the application of the ideal adsorbed solution theory-equivalent background compound (IAST-EBC) model and its simplified version for PAC dose prediction. Four raw water samples were employed, and the corresponding C0,EBC values, indicating NOM competitiveness, were calculated. The results showed that the IAST-EBC model presented ideal predictive performance in 2-MIB adsorption under both equilibrium and nonequilibrium conditions and the C0,EBC values of the Huangpu River (8800 ng/L) and Qiantang River (10300 ng/L) were high, representing the higher NOM competitiveness in these two rivers, which may be caused by municipal effluent and industrial wastewater discharge. In contrast, Tai Lake water showed a lower C0,EBC value (6400 ng/L), which was likely associated with algae and other microbial activities. The fluorescence index (FI, the ratio of Ex/Em = 370/470 nm to Ex/Em = 370/520 nm) can be applied to estimate C0,EBC, thus facilitating prediction. Our study also showed that the IAST-EBC model can be further simplified under lower initial 2-MIB concentrations or longer contact times, which is particularly useful for practical applications.

SERS activity with tenfold detection limit optimization on a type of nanoporous AAO-based complex multilayer substrate.

Most of SERS applications are constricted by heterogeneous hotspots and aggregates of nanostructure, which result in low sensitivity and poor reproducibility of characteristic signals. This work intends to introduce SERS properties of a type of SERS-active substrate, Au-CuCl2-AAO, which is innovatively developed on a porous anodic alumina oxide (AAO) template. Spectral measuring results of Rhodamine 6G (R6G) on this substrate optimized by controlling morphology and gold thickness showed that enhancement factor (2.30 × 10(7)) and detection limit (10(-10) M) were both improved and represented better performance than its template AAO. Homogenous hot spots across the region of interest were achieved by scanning SERS intensity distribution for the band at 1505 cm(-1) in 5 × 5 µm(2) area. Furthermore, the promising SERS activity of the flower-patterned substrate was theoretically explained through simulation of the electromagnetic field distribution. In addition, this SERS substrate is proposed for applications within the field of chemical and biochemical analyses.