The exploration of simultaneous removal of co-existing or multiple pollutants from water by the means of nanomaterials paves a new avenue that is free from secondary pollution and inexpensive. In the aquatic environment, river water contains a mixture of ions, which can influence the adsorption process. In this respect, removing heavy metal ions becomes a true challenge. Here, four heavy metal ions, namely, Pb 2+ , Cd 2+ , Cu 2+ , and Ni 2+ , have been successfully removed simultaneously from river water using ultrafine mesoporous magnetite (Fe 3 O 4 ) nanoparticles (UFMNPs) based on the affinity of these metal ions toward the UFMNP surfaces as well as their unique mesoporous structure, promoting the easy adsorption. The individual removal efficiencies of Pb 2+ , Cd 2+ , Cu 2+ , and Ni 2+ ions from river water were 98, 87, 90, and 78%, respectively, whereas the removal efficiencies of the mixed Pb 2+ , Cd 2+ , Cu 2+ , and Ni 2+ ions were 86, 80, 84, and 54%, respectively, in the same river water. Thus, the data clearly indicate the complex removal of heavy metal ions in multi-ion systems. This study has demonstrated the huge potential of UFMNPs to be effective for their use in wastewater treatment, especially to simultaneously remove multiple heavy metal ions from aqueous media.

All chemical reactions can be divided into a series of single molecule reactions (SMRs), the elementary steps that involve only isomerization of, dissociation from, and addition to an individual molecule. Analyzing SMRs is of paramount importance to identify the intrinsic molecular mechanism of a complex chemical reaction, which is otherwise implausible to reveal in an ensemble fashion, owing to the significant static and dynamic heterogeneity of real‐world chemical systems. The single‐molecule measurement and manipulation methods developed recently are playing an increasingly irreplaceable role to detect and recognize short‐lived intermediates, visualize their transient existence, and determinate the kinetics and dynamics of single bond breaking and formation. Notably, none of the above SMRs characterizations can be realized without the aid of a confined space. Therefore, this Review aims to highlight the recent progress in the development of confined space enabled single‐molecule sensing, imaging, and tuning methods to study chemical reactions. Future prospects of SMRs research are also included, including a push toward the physical limit on transduction of information to signals and vice versa, transmission and recording of signals, computational modeling and simulation, and rational design of a confined space for precise SMRs.

Dark-field and Raman microscopy to probe the single NP electrochemistry in real time.

In this study, electrochemical reaction mechanism of adenosine monophosphate (AMP) and adenosine triphosphate (ATP) on a silver mesh was investigated in acetate buffer using spectroelectrochemical technique. The results indicate that AMP (or ATP) can form a complex with silver ion originating from a silver mesh when a positive potential was applied. In these complexes, silver ion coordinates with AMP or ATP via their phosphate group. However, when a negative potential was applied, the formed complex disappeared. The complex reaction is therefore an electrochemically reversible process. Further studies using surface-enhancement Raman spectroscopy (SERS) have shown that AMP (or ATP) has a parallel or perpendicular orientation to the silver mesh surface, which is governed by their different binding sites (adenine ring, ribose, and phosphate groups). Herein, the adenine nucleotide-silver mesh surface complexes have displayed a promising biosensing capacity.