Sensing Material-Dependent Interference of Multiple Heavy Metal Ions: Experimental and Simulated Thermodynamics Study on Cu(II), Cd(II), and As(III) Electroanalysis.

Interference among multiple heavy metal ions (HMIs) is a significant problem that must be solved in electroanalysis, which extremely restricts the practical popularization of electrochemical sensors. However, due to the limited exploration of the intrinsic mechanism, it is still difficult to confirm the influencing factors. In this work, a series of experimental and theoretical electroanalysis models have been established to investigate the electroanalysis results of Cu(II), Cd(II), As(III), and their mixtures, which were based on the simple structure and stable coordination of nickel single-atom catalysts. X-ray absorption spectroscopy and density functional theory calculations were used to reveal the underlying detection mechanism of the 50-fold boosting effect of Cu(II) on As(III) while Cd(II) inhibits As(III). Combining the application of the thermodynamic model and Fourier transform infrared reflection, the specific interaction of the nanomaterials and HMIs on the interface is considered to be the fundamental source of the interference. This work opens up a new way of thinking about utilizing the unique modes of interplay between nanomaterials and HMIs to achieve anti-interference intelligent electrodes in stripping analysis.

Layer-by-layer assembly and electrochemical study of a 4-aminothiophenol and ytterbium(III) trifluoromethanesulfonate hydrate film on a gold electrode.

We report on the layer-by-layer assembly and electrochemical properties of 4-aminothiophenol (P-ATP) and ytterbium(III) trifluoromethanesulfonate hydrate (Yb(OTf)(3)) film supported on a gold surface. The fabricated film was characterised electrochemically using redox couples Fe(CN)(6)(3-/4-), complemented with imaging using atomic force microscopy (AFM). The electrocatalytic activity of the prepared electrodes was studied using cyclic and differential pulse voltammetries. Electrochemical measurements show that the P-ATP/Yb(OTf)(3) modified electrode has superb activity towards hydroquinone (HQ) oxidation and that there is a significant improvement in the electrode stability and reproducibility due to the covalent and coordination reactions.

A conventional route to scalable morphology-controlled regular structures and their superhydrophobic/hydrophilic properties for biochips application.

We use a conventional and straightforward route to fabricate scalable morphology-controlled regular structures. This route is based on the etching of PDMS microlens array in CF4 and CF4/O2 plasma. PDMS microlens array can be changed to regularly isolated microdot structures array in CF4 plasma. Microbowl shaped structures array can be reached in CF4/O2 plasma. Moreover, a set of structures after CF4 plasma treatment display superhydrophobicity, while a set of structures after CF4/O2 plasma treatment present hydrophilicity. DNA molecules can be readily enriched on the hydrophilic surface. We believe that the regular structure array surfaces provide a useful inspiration towards biomolecular detection and transportation in biochips.

Novel magnetic nickel telluride nanowires decorated with thorns: synthesis and their intrinsic peroxidase-like activity for detection of glucose.

The magnetic nickel telluride with thorny nanostructure is directly synthesized for the first time via a hydrothermal method. It was used to detect H2O2 and glucose with a limit of detection of 25 nM (linear range = 0.1-0.5 µM) and 0.42 µM (linear range = 1-50 µM), respectively.

Removal of cobalt ions from aqueous solution by an amination graphene oxide nanocomposite.

A newly designed amination graphene oxide (GO-NH2), a superior adsorption capability to that of activated carbon, was fabricated by graphene oxide (GO) combining with aromatic diazonium salt. The resultant GO-NH2 maintained a high surface area of 320 m(2)/g. When used as an adsorbent, the GO-NH2 demonstrated a very quick adsorption property for the removal of Co(II) ions, more than 90% of Co(II) ions could be removed within 5 min for dilute solutions at 0.3g/L adsorbent dose. The adsorption capability approaches 116.35 mg/g, which is one of the highest capabilities of today's materials. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that the Co(II) ions adsorption on GO-NH2 was a spontaneous process. Considering the superior adsorption capability, the GO-NH2 filter membrane was fabricated for the removal of Co(II) ions. Membrane filtration experiments revealed that the removal capabilities of the materials for cobalt ions depended on the membrane's thickness, flow rate and initial concentration of Co(II) ions. The highest percentage removal of Co(II) exceeds 98%, indicating that the GO-NH2 is one of the very suitable membrane materials in environmental pollution management.

Selective adsorption toward toxic metal ions results in selective response: electrochemical studies on a polypyrrole/reduced graphene oxide nanocomposite.

Highly selective adsorption of a polypyrrole/reduced graphene oxide nanocomposite toward Hg(2+) results in electrochemically selective detection of Hg(2+). This interesting finding is of practical utility compared to the biotechniques and surface functionalization-based methods.

Electropolymerized surface ion imprinting films on a gold nanoparticles/single-wall carbon nanotube nanohybrids modified glassy carbon electrode for electrochemical detection of trace mercury(II) in water.

Electrochemical detection of Hg(II) using a electropolymerized ion imprinting poly(2-mercaptobenzothiazole) films at the surface of gold nanoparticles/single-walled carbon nanotube nanohybrids modified glassy carbon electrode (PMBT/AuNPs/SWCNTs/GCE) is described for the first time. The Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE sensor exhibits larger binding to functionalized capacity, larger affinity, faster binding kinetics and higher selectivity to template Hg(II). The differential pulse anodic stripping voltammetry (DPASV) response of the Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE sensor to Hg(II) is ca. 3.7- and 10.5-fold higher than that at the non-imprinted PMBT/AuNPs/SWCNTs/GCE and the imprinted PMBT/AuNPs/GCE, respectively, and the detection limit for Hg(II) is 0.08 nM (S/N=3, which is well below the guideline value given by the World Health Organization) and a sensitivity of 0.749 µA nM(-1) was obtained. Excellent wide linear range (0.4-96.0 nM) and good repeatability (relative standard deviation of 2.6%) were obtained for Hg(II). The interference experiments show that Ag(I), Pb(II), Cd(II), Zn(II) and Cu(II) had little or no influence on the Hg(II) signal. These values, particularly the high sensitivity and excellent selectivity in contrast to the values reported previously in the area of electrochemical Hg(II) detection, demonstrate the analytical performance of the Hg(II)-imprinted PMBT/AuNPs/SWCNTs/GCE toward Hg(II) is superior to the existing electrodes and could be used for efficient determination of Hg(II) in natural water samples.

Stripping voltammetric detection of mercury(II) based on a surface ion imprinting strategy in electropolymerized microporous poly(2-mercaptobenzothiazole) films modified glassy carbon electrode.

This work reports a surface ion imprinting strategy in electropolymerized microporous poly(2-mercaptobenzothiazole) (MPMBT) films at the surface of glassy carbon electrode (GCE) for the electrochemical detection of Hg(II). The Hg(II)-imprinted MPMBT/GCE exhibits larger binding to functionalized capacity, faster binding kinetics and higher selectivity to template Hg(II) due to their high ratio of surface-imprinted sites, larger surface-to-volume ratios, the complete removal of Hg(II) templates and larger affinity to Hg(II). The square wave anodic stripping voltammetry (SW ASV) response of the Hg(II)-imprinted MPMBT/GCE to Hg(II) is ca. 3.0 and 5.9 times larger than that at the direct imprinted poly(2-mercaptobenzothiazole) modified GCE and non-imprinted MPMBT/GCE sensor, respectively; and the detection limit for Hg(II) is 0.1nM (which is well below the guideline value given by the World Health Organization). Excellent wide linear range (1.0-160.0nM) and good repeatability (relative standard deviation of 2.5%) were obtained for Hg(II). The interference experiments showed that mercury signal was not interfered in the presence of Pb(II), Cd(II), Zn(II), Cu(II) and Ag(I), respectively. These values, particularly the high sensitivity and excellent selectivity compared favorably with previously reported methods in the area of electrochemical Hg(II) detection, demonstrate the feasibility of using the prepared Hg(II)-imprinted MPMBT/GCE for efficient determination of Hg(II) in aqueous environmental samples.