An effective strategy for preparation amperometric biosensor by using the phosphonic acid-functionalized silica nanoparticles (PFSi NPs) as special modified materials is proposed. In such a strategy, glucose oxidase (GOD) was selected as model protein to fabricate glucose biosensor in the presence of phosphonic acid-functionalized silica nanoparticles (PFSi NPs). The PFSi NPs were first modified on the surface of glassy carbon (GC) electrode, then, GOD was adsorbed onto the PFSi NPs film by drop-coating. The PFSi NPs were characterized by transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR) spectra. The interaction of PFSi NPs with GOD was investigated by the circular dicroism spectroscopy (CD). The results showed PFSi NPs could essentially maintain the native conformation of GOD. The direct electron transfer of GOD on (PFSi NPs)/GCE electrode exhibited excellent electrocatalytic activity for the oxidation of glucose. The proposed biosensor modified with PFSi NPs displayed a fast amperometric response (5 s) to glucose, a good linear current–time relation over a wide range of glucose concentrations from 5.00 × 10−4 to 1.87 × 10−1 M, and a low detection limit of 2.44 × 10−5 M (S/N = 3). Moreover, the biosensor can be used for assessment of the concentration of glucose in many real samples (relative error < 3%). The GOD biosensor modified with PFSi NPs will have essential meaning and practical application in future that attributed to the simple method of fabrication and good performance.

In this work, the silica– phytic acid (SiO2–PA) nanocomposites were synthesized by the method of reverse microemulsion and electrostatic binding. The newly designed materials were used to develop a novel glucose biosensor by immobilizing glucose oxidase (GOx) onto the SiO2–PA nanocomposites film on the surface of glassy carbon electrode (GCE). The characteristics of SiO2–PA nanocomposites and GOx were obtained by using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) technique. All the results indicated that silica nanoparticales were modified with phosphate radicals successfully and the biomimetic surface was built. The entrapped GOx could preserve its bioactivity and exhibited an excellent electrochemical behavior with a formal potential of −0.548 V in phosphate buffer solution (PBS) (pH=7). Response studies to glucose were carried out using differential pulse voltammetry (DPV). The results indicated that the modified electrode can be used to determine glucose without interference from l-ascorbic acid (AA) and uric acid (UA) with the low detection limit of 0.012 mM. The comparison tests of DPVs of different electrodes in the absence and presence of glucose were also studied. The biosensor can also be used for quantification of the concentration of glucose in real samples.Highlights► Innovative SiO2–PA NPs were prepared by reverse microemulsion and electrostatic binding method. ► Biomimetic surface provided by SiO2–PA NPs could preserve bioactivity of GOx. ► The GOx biosensor modified by SiO2–PA NPs exhibited an excellent electrochemical behavior.

The intrinsic properties and application potential of nanocolloids are mainly determined by size, shape, composition, and structure. In this case, a novel glucose biosensor was developed by using the chitosan–polypyrrole (CS–PPy) nanocomposites as special modified materials that coating onto the surface of glassy carbon electrode (GCE). The CS–PPy nanocomposites were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Moreover, the interaction of CS–PPy nanocomposites with glucose oxidase (GOD) was also investigated by the combined studies with Fourier transform infrared spectroscopy (FTIR) and circular dichroism spectroscopy (CD). Due to the conductivity of polypyrrole (PPy), good biocompatibility of CS, and advantages of nanoparticles, CS–PPy nanocomposites were chosen and designed to modify the GCE for the retention of GOD's biological activity and the vantage of electron transfer between GOD and electrodes. The GOD biosensor exhibited a fast amperometric response (5 s) to glucose, a good linear current–time relation over a wide range of glucose concentrations from 5.00 × 10− 4 to 1.47 × 10− 1 M, and a low detection limit of 1.55 × 10− 5 M. The GOD biosensor modified with CS–PPy nanocomposites will have essential meaning and practical application in future that attributed to the simple method of fabrication and good performance.Highlights► A novel electrochemical glucose biosensor based on CS–PPy nanocomposite is developed. ► The prepared CS–PPy provided a micro-environment with biocompatibility and good conductivity for enzyme. ► The glucose biosensor modified by CS–PPy nanocomposites showed good electrochemical performance.

In this paper, a luminescent complex of terbium–acetylsalicylic acid (Tb-ASA) was studied for the first time using combination of the quantum chemical calculation, fluorescence spectroscopic method and X-ray photoelectron spectroscopy (XPS). The results from the quantum chemical calculation indicated that it is possible for the energy-transfer from ASA to Tb (III); Fluorescence spectroscopy demonstrated that there is an intramolecular energy-transfer from ASA to Tb with the efficiency (III) of about 87.9% under an excitation at 308 nm. The XPS indicated that the coordinate covalent bond between Tb and O existed in the complex of Tb-ASA leads to the effective energy transfer from ASA to Tb (III) because the energy transfer rate may be improved with reducing the distance between the ligand and Tb (III). The results will have important values for the studies of this type of complexes.

Complexes [PF6⊂(Ag3(titmb)2](PF6)2 (8) and {SbF6⊂[Ag3(titmb)2](SbF6)2}·H2O·1.5 CH3OH (9) are obtained by reaction of titmb and Ag+ salts with different anions (PF6− and SbF6−), and crystal structures reveal that they are both M3L2 cage complexes with short Ag⋯F interactions between the silver atoms and the fluorine atoms of the anions. In complex 8, a novel cage dimer is formed by weak Ag⋯F contacts; an unique cage tetramer formed via Ag⋯π interactions (Ag⋯η5-imidazole) between dimers and an infinite 1D cage chain is presented. However, each of the external non-disordered SbF6− anions connect with six cage 9s via Ag⋯F contacts, and each cage 9 in turn connects with three SbF6− anions to form a 2D network cage layer; and the layers are connected by π–π interactions to form a 3D network. The anion-exchange reactions of four Ag3L2 type complexes ([BF4⊂(Ag3(titmb)2](BF4)2 (6), [ClO4⊂(Ag3(titmb)2](ClO4)2 (7b), [PF6⊂(Ag3(titmb)2](PF6)2 (8) and [SbF6⊂(Ag3(titmb)2](SbF6)2·1.5CH3OH (9)) with tetrahedral and octahedral anions (ClO4−, BF4−, PF6− and SbF6−) are also reported. The anion-exchange experiments demonstrate that the anion selective order is SbF6− > PF6− > BF4−, ClO4−, and this anion receptor is preferred to trap octahedral and tetrahedral anions rather than linear or triangle anions; SbF6− is the biggest and most preferable one, so far. The dimensions of cage complexes with or without internal anions, anion-exchange reactions, cage assembly and anion inclusions, silver(I) coordination environments, Ag–F and Ag–π interactions of Ag3L2 complexes 1–9 are discussed.

Complexes [PF6⊂(Ag3(titmb)2](PF6)2 (8) and {SbF6⊂[Ag3(titmb)2](SbF6)2}·H2O·1.5 CH3OH (9) are obtained by reaction of titmb and Ag+ salts with different anions (PF6− and SbF6−), and crystal structures reveal that they are both M3L2 cage complexes with short Ag⋯F interactions between the silver atoms and the fluorine atoms of the anions. In complex 8, a novel cage dimer is formed by weak Ag⋯F contacts; an unique cage tetramer formed via Ag⋯π interactions (Ag⋯η5-imidazole) between dimers and an infinite 1D cage chain is presented. However, each of the external non-disordered SbF6− anions connect with six cage 9s via Ag⋯F contacts, and each cage 9 in turn connects with three SbF6− anions to form a 2D network cage layer; and the layers are connected by π–π interactions to form a 3D network. The anion-exchange reactions of four Ag3L2 type complexes ([BF4⊂(Ag3(titmb)2](BF4)2 (6), [ClO4⊂(Ag3(titmb)2](ClO4)2 (7b), [PF6⊂(Ag3(titmb)2](PF6)2 (8) and [SbF6⊂(Ag3(titmb)2](SbF6)2·1.5CH3OH (9)) with tetrahedral and octahedral anions (ClO4−, BF4−, PF6− and SbF6−) are also reported. The anion-exchange experiments demonstrate that the anion selective order is SbF6− > PF6− > BF4−, ClO4−, and this anion receptor is preferred to trap octahedral and tetrahedral anions rather than linear or triangle anions; SbF6− is the biggest and most preferable one, so far. The dimensions of cage complexes with or without internal anions, anion-exchange reactions, cage assembly and anion inclusions, silver(I) coordination environments, Ag–F and Ag–π interactions of Ag3L2 complexes 1–9 are discussed.