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A highly stable and dispersed aqueous nanocomposite of silver nanoparticles/poly(vinyl alcohol-co-ethylene glycol)/poly(3-aminophenyl boronic acid) (Ag/(PVA-PEG)/PABA) was synthesized. PVA and PEG was blended at the optimum volume ratio of 16:4 to obtain poly(vinyl alcohol-co-ethylene glycol) (PVA-PEG) blend. 3-Aminophenyl boronic acid served as the reductant of silver nitrate and was in situ oxidatively polymerized to obtain poly(3-aminophenyl boronic acid) (PABA). Subsequently, (PVA-PEG) blend served as matrix for PABA polymerization. The polymer blend helped to improve PABA solubility by providing platform for PABA anchoring, through covalent bonding with the free hydroxyl groups of the blend. Additionally, PABA is a highly conducting polymer, hence the synthesized nanocomposite demonstrated improved conductivity. The maximum absorption peak of Ag/(PVA-PEG)/PABA was at 422 nm, with particle sizes between 10 and 15 nm and zeta potential value of 25.8 mV. FESEM showed spherical AgNPs sprinkled on the surface of the nanocomposite while 40% Ag was presented in EDX result. The Ag/(PVA-PEG)/PABA exhibited good antibacterial potency against Bacillus cereus and Escherichia coli where the ruptured bacterial cell was observed on FESEM. Importantly, it showed reliable biocompatibility without imparting deleterious red blood cell hemolysis and non-cytotoxic to normal human cell line. Overall, these results emphasized the exciting biomedical potentials of Ag/(PVA-PEG)/PABA nanocomposite.

A binder-free electrode has been fabricated by directly growing MoSe2 nanosheets on the macroporous Ti mesh skeleton (MoSe2 NS-Ti) via a facile hydrothermal deposition method. The as-prepared MoSe2 NS-Ti electrode is characteristic of robust porous hierarchical nanostructures with large surface area, enriched exposed active edges and improved electroconductivity. As a result, in comparison to the bare MoSe2 electrode, the MoSe2 NS-Ti electrode shows dramatically enhanced electrocatalytic activity and pseudocapacitive performance due to its desirable structural features.

In this study, a sensitive and selective colorimetric probe for fluoride detection was established. The detection strategy is based on the interaction between dithiobis(succinimidylpropionate) modified gold nanoparticles (DSP@AuNP) and 3-aminophenylboronic acid (APBA), which was used as the recognition molecule for fluoride. AuNPs were modified with DSP, a notable amine coupling ligand, so that they can bind with the amino group of APBA to furnish a colorimetric probe denoted as APBA–DSP@AuNP. The boronic acid moiety of the probe is appropriately positioned to bind with fluoride in a slightly acidic environment provided by phosphate buffer (pH = 5.2) through the Lewis acid–base interaction, resulting in the probe's aggregation. The color of APBA–DSP@AuNP undergoes different color transitions from ruby red to purple and blue-gray within 15 minutes, depending on the concentration of fluoride. The absorbance ratio (A650/A520) was used as the analytical signal, which was linear with fluoride concentration over two ranges of 75–1000 μM and 1000–3000 μM. The limit of detection was estimated as 56.5 μM, which was much lower than the maximum acceptable limit of fluoride (210 μM) in drinking water given by the US EPA. The practical applicability of APBA–DSP@AuNP was demonstrated by applying it to fluoride detection in tap water, with acceptable accuracy (97 to 102%).

A facile molecular wedging method is used to exfoliate graphite flakes into graphene sheets, with concurrent functionalization to form pyrene-1-boronic acid functionalized graphene (PBA/G). Different techniques are used to characterize the prepared materials such as field emission scanning electron microscope, energy dispersive X-ray analyzer, Raman, Fourier transformed infrared spectroscopy and fluorescence spectroscopy to evaluate their structural and morphological characteristics. The intercalation of PBA into graphite sheets, followed by exfoliation can be observed under the electron microscope. Elemental analyses show that the PBA acts more than intercalant, it is functionalized onto the graphene sheets upon exfoliation to form PBA/G. Raman analysis indicates PBA/G has a lower number of graphene layers as a result of successful exfoliation by PBA. Electrochemical impedance studies show that the PBA/G possesses high affinity for dopamine through the diol groups interaction, which renders it to have enhanced detection for dopamine.

Sialic acid (SA) is a notable tumor marker in human. Its increased level beyond the normal concentration in human biological samples is related to different kinds of cancers development. In this contribution, a novel colorimetric assay is reported for SA detection in form of N-acetylneuraminic acid. The sensitive detection strategy is proposed via the specific SA induced aggregation of 3‑aminophenyl boronic acid (3APBA) assembled on dithiobis(succinimidylpropionate) functionalized gold nanoparticles (AuNPs-DSP). DSP was functionalized on AuNPs through a strong Au S interaction and 3APBA was assembled on AuNPs-DSP by the amine coupling reaction between the carboxyl group of DSP on gold nanoparticles surface and the amino group of 3APBA to generate a covalent amide bond. The addition of 3APBA to buffered AuNPs-DSP generated a ruby red colloidal nanosensor. With increasing concentration of SA, a probe color turned rapidly from red to blue-gray via aggregation of AuNPs-DSP-3APBA. At optimal conditions, the absorbance ratio (A700/A520) was linear with SA concentrations ranging from 0.08 to 0.25 mM and 0.30–0.70 mM. A limit of detection of 35.0 μM was achieved which is the lowest amongst reported colorimetric methods for SA determination. The practical efficacy of the assay was demonstrated on human serum, along with no interfering effects and satisfactory accuracy and precision.

A click chemistry assay based on a newly discovered DNAzyme, CLICK-17, with azide modified gold nanoparticles (azide-AuNPs) and alkyne capped dsDNA (alkyne-linker DNA) was employed for novel and selective detection of Cu2+ visually. The strategy involved using CLICK-17 to mediate a catalytic reaction for triazole formation between azide-AuNPs and alkyne-linker DNA under the help of Cu2+ (without sodium ascorbate) or Cu+, which eventually led to the aggregation of AuNPs. The obvious color change from ruby red to bluish purple was then observed by the naked eye and the absorbance peak shifted from 525 to 570 nm. Interestingly, CLICK-17 and Cu+-catalyzed click reaction had the best performance compared to either Cu+ alone or CLICK-17 and Cu2+-mediated reaction in terms of the reaction time and sensitivity. This system has been demonstrated to allow quantitative measurement of Cu2+ with a detection limit as low as 26.8 nM and also has high specificity that can distinguish Cu2+ from other metal ions. Further, the method was tested with a real mineral water sample for Cu2+ concentration determination. Satisfactory recoveries of 90.8% and 99.8% were achieved.

In this work, we present the novel robust material, modified natural rubber (NR) composites filled with gold nanoparticles (AuNPs). To investigate its outstanding properties, dielectric, electrical and mechanical properties of NR and modified NR composites filled with gold nanoparticles (AuNPs) were studied. The NR and all composite films were prepared by using solution casting method. The size of the synthetic AuNPs was analyzed by Transmission Electron Microscope (TEM) technique. The dispersion of AuNPs fillers within the NR matrix was investigated by scanning electron microscopy (SEM). Dielectric and electrical properties of NR composites were analyzed as function of filler concentration and frequency in a range of 100-105 Hz, observed with the LCR analyzer. Elastic modulus of all samples was evaluated by a strain gauge set up. It was found that the dielectric constant is inversely related to the frequency. Moreover, the dielectric constant and the electrical conductivity strongly increase in proportional to the AuNPs filler content. In comparison at AuNPs concentration of 0.0010% by weight, it was observed that the dielectric constant of NR composites is eight times larger than the pure NR, while the mechanical properties of the NR composites slightly increase in proportional to the AuNPs. As consequence, the interfacial surface area significantly affects the electrical and mechanical properties of those NR composites.

Arsenic (As) in soils and hair collected from schools in Ron Phibun district, Nakhon Si Thammarat province, Thailand, where former tin mining operation were located, was determined by hydride generation atomic absorption spectrophotometry. The relationship between As content in soils and hair with distance from secured landfill was also investigated. Soil and hair samples were collected from 6 schools in summer (February) and rainy season (July). For soils, silt+clay (

Hierarchical molybdenum disulfide microspheres have been successfully prepared through a zinc ion-assisted hydrothermal route followed by an acid corrosion strategy. It is found that the MoS2 microspheres comprised of numerous nanosheets with few-layered feature exhibit a 3D flower-like morphology. It is believed that the MoS2/ZnS composites can act as a precursor for the formation of hierarchical MoS2 microspheres. Additionally, the electrochemical properties of the as-prepared MoS2 microspheres as an electrode material for supercapacitors have also been investigated. Compared with the MoS2 nanosheet, the resultant MoS2 microsphere demonstrates superior pseudcapacitive properties including high specific capacitance, good cycling and rate capability, which could be credited to its novel hierarchical architecture feature.

Tin sulfide (SnS) becomes a competitive alternative anode material for lithium ion batteries (LIBs) due to its cost-effects and high theoretical capacity. Herein, a simple freeze-drying and annealing synthetic strategy was exploited to in-situ couple SnS with nitrogen-doped porous carbon nanosheets to fabricate SnS@NPC nanocomposites. In this nanostructure, SnS nanoparticles were well embedded into citric acid-derived nitrogen-doped carbon hierarchical frameworks with enlarged surface areas and abundant porosity. Besides, the reversible Li-ion storage property of this novel nanostructured anode in LIBs was also investigated and compared with the bare SnS counterpart. It was indicated that the SnS@NPC hybrid electrode exhibited a tremendously boosted electrochemical performance. After cycling 200 times at 100 mA g−1 and 300 times at 1000 mA g−1, a high specific capacity of 851.5 mA h g−1 and 607.6 mA h g−1 was remained respectively. Furthermore, with SnS@NPC as anode and the activated carbon (AC) as cathode, a new-type of lithium ion capacitor (LIC) was also fabricated, which exhibited a specific capacitance of 70.1 F g−1 at 0.1 A g−1 and a maximum energy density of 155.5 Wh kg−1 at 213.6 W kg−1. The well-engineered nanostructures as well as the aroused synergistic effect between SnS and nitrogen-doped carbon materials are considered to be responsible for the enhanced electrochemical property.

The silver/poly(3-aminophenyl boronic acid)/sodium alginate nanogel (Ag@PABA-SA) was fabricated through green, in situ chemical oxidative polymerization method. 3-Aminophenyl boronic acid (APBA) served as the room temperature reductant of AgNO3 which acted as an oxidant towards the polymerization of APBA to its conducting polymeric form (PABA). Importantly with SA present, PABA will bind to hydroxyl groups of SA through covalent bonding to generate PABA-SA semi-interpenetrating network, on which AgNPs were concomitantly deposited. This results highly stable, dispersed polymer based AgNPs. The morphology, size, surface charge, composition and thermal stability of nanogel was characterized by UV-vis, Raman and FTIR spectroscopy, TEM, FESEM, EDX, XRD, DLS and zeta potential analysis, TGA and DTG. The Ag@PABA-SA nanogel was investigated as colorimetric probe towards H2O2 detection. Wide linearity from 5 to 1000 μM H2O2, with low limit of detection of 1.0 μM in addition to satisfactory precision (< 3.5 %) and recovery (95-105 %) and high selectivity was achieved.

The association of a plasmonic nano-antenna with single-molecule FRET technique presents new prospects to investigate the dynamics of biological molecules. However, the presence of a plasmonic nano-antenna significantly modifies the FRET rate and efficiency; this makes its applicability to the prevalent single-molecule FRET experiments unclear. Herein, using gold nanoparticle antennas of different sizes and DNA hairpins labelled with FRET pairs (Cy3 and Cy5) as the model system, we performed experiments to study the folding dynamics of single DNA hairpins at various salt concentrations. Our results indicate that gold nanoparticle antennas can enhance single-molecule fluorescence of Cy3 and Cy5 up to 3-5 folds, substantially reduce the FRET efficiency, and alter the obtained FRET efficiency histograms. However, the folding dynamics of DNA hairpins remains unaffected, and the correct kinetic and dynamic information can still be extracted from the seriously modified FRET efficiencies. Therefore, our experiments demonstrate the feasibility and compatibility for applying plasmonic nano-antennas to the mostly used single-molecule FRET assays, which provide a broad range of possibilities for the future applications of these nano-antennas in studying various essential biological processes.

In this paper, we developed a facile approach to synthesize well-dispersed 3D hierarchical porous MoS2 architectures with assistance of polyacrylate and demonstrated their applications in lithium ion batteries (LIBs). It was confirmed that the uniform flower-like MoS2 architectures were assembled by nanosheets comprising about ∼10 stacking layers. Polyacrylate was revealed to have a significant impact on controlling the formation of the uniform hierarchical flower-like architectures with desirable dispersity. It was believed that the polyacrylate could direct assembly of the MoS2 nanosheets into hierarchical structures and could well stabilize and disperse MoS2 architectures. Furthermore, a stable cycling capability (839 mAh g-1 at 0.1 A g-1 after 120 cycles) and superior rate ability of the MoS2 architectures were achieved as anodes for LIBs. This remarkably enhanced electrochemical property could be ascribed to their beneficial structural features and surface-dominated capacitive contribution.