Fen-Ying Kong

A paper disk equipped with graphene/polyaniline/Au nanoparticles/glucose oxidase biocomposite modified screen-printed electrode: toward whole blood glucose determination.

In this work, a convenient, fast, low cost, small sample volume and in situ detection of glucose in human whole blood has been developed by using a disposable screen-printed carbon electrode (SPCE) coupled with a paper disk. To perform the assay, the SPCE was modified with graphene/polyaniline/Au nanoparticles/glucose oxidase (Gr/PANI/AuNPs/GOD) biocomposite and then covered by a paper disk impregnated with the sample. After introducing PBS on the paper disk, the electrochemical measurement was carried out. The assay was based on measuring the current decrease of flavin adenine dinucleotide (FAD) in GOD provoked by the enzyme-substrate reaction using differential pulse voltammetry (DPV). The analytical performance was comparable to conventional methods, and covered the full range of clinically relevant concentrations of glucose in whole blood. This new paper-based electrochemical glucose sensor shows promise in applying point-of-care (POC) device in whole blood tests, and particularly being appropriate for use in the developing world and in resource-limited settings.

Reduced graphene oxide-Hemin-Au nanohybrids: Facile one-pot synthesis and enhanced electrocatalytic activity towards the reduction of hydrogen peroxide

A facile and effective strategy is demonstrated for the synthesis of ternary reduced graphene oxide-Hemin-Au (rGO-H-Au) nanohybrids. The nanohybrids were synthesized through a one-pot in situ reduction of GO and HAuCl4 under alkaline conditions using GO, Hemin and HAuCl4 as the starting materials. The synthesis process can be finished within 1h in a solution phase, without adding any additional surfactant, stabilizing agent and toxic or harsh chemical reducing agents. The resulting nanohybrids were characterized by UV-vis spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), and so on. Electrochemical measurements showed that the rGO-H-Au nanohybrids exhibited good electrocatalytic activity for the reduction of hydrogen peroxide (H2O2). Based on this property, a simple and highly sensitive amperometric biosensor for H2O2 had been developed. The linear relationships were obtained from 0.1 µM to 40 µM and the detection limit was estimated to be 30 nM. The simple and sensitive sensing platform showed great promising applications in the pharmaceutical, clinical and industrial detection of H2O2.

Unique Roles of Gold Nanoparticles in Drug Delivery, Targeting and Imaging Applications.

Nanotechnology has become more and more potentially used in diagnosis or treatment of diseases. Advances in nanotechnology have led to new and improved nanomaterials in biomedical applications. Common nanomaterials applicable in biomedical applications include liposomes, polymeric micelles, graphene, carbon nanotubes, quantum dots, ferroferric oxide nanoparticles, gold nanoparticles (Au NPs), and so on. Among them, Au NPs have been considered as the most interesting nanomaterial because of its unique optical, electronic, sensing and biochemical properties. Au NPs have been potentially applied for medical imaging, drug delivery, and tumor therapy in the early detection, diagnosis, and treatment of diseases. This review focuses on some recent advances in the use of Au NPs as drug carriers for the intracellular delivery of therapeutics and as molecular nanoprobes for the detection and monitoring of target molecules.

Direct electrolytic exfoliation of graphite with hemin and single-walled carbon nanotube: Creating functional hybrid nanomaterial for hydrogen peroxide detection

We present a new, facile and efficient method to prepare functional graphene (GN) hybrid nanomaterials using direct electrolytic exfoliation of graphite robs in hemin (HN) and single-walled carbon nanotube (SWCNT) solution. During the exfoliation process, HN and SWCNT were simultaneously adsorbed on the surface of GN nanosheets through noncovalent π-π interaction, and then 3D GN-HN-SWCNT hybrid nanomaterials were formed. Due to the synergic effect among GN, HN, and SWCNT, these hybrid nanomaterials possessed excellent electrocatalysis properties and were used to construct novel electrochemical biosensor for H2O2 determination. The results displayed a wide linear range of 0.2 μM-0.4 mM and a low detection limit of 0.05 μM. Moreover, the developed sensor was successfully applied for real samples, such as beverages, and showed great promise in routine sensing applications.

Preparation of a boronate affinity silica stationary phase with enhanced binding properties towards cis-diol compounds

In this study, a boronate affinity silica stationary phase with enhanced binding properties towards cis-diol compounds was prepared through the combination of surface-initiated atom transfer radical polymerization (SI-ATRP) with a Wulff-type boronate as affinity ligand. The stationary phase showed good hydrophilicity and improved binding strength toward adenosine, with binding constant to be as low as 2.38×10-4M. The column exhibited excellent binding specificity, low binding pH (≥5.5) and high binding capacities (80.1μmol adenosine g-1 at pH 7.0 and 45.2μmol adenosine g-1 at pH 5.5, respectively). The stationary phase was applied as adsorbent for the selective extraction of nucleosides in human urine with excellent specificity and high enrichment efficiency. These results demonstrated that this stationary phase could be favorably applied for selective capture and enrichment of cis-diol compounds in complex samples.

UV-assisted photocatalytic synthesis of highly dispersed Ag nanoparticles supported on DNA decorated graphene for quantitative iodide analysis.

Herein, we report, for the first time, the synthesis of reduced graphene oxide-DNA-Ag (RGO-DNA-Ag) nanohybrids by ultraviolet (UV) irradiation of aqueous solutions of GO and Ag ions in the presence of DNA. The morphology and microstructure characterizations of the resultant nanohybrids reveal that the proposed method leads to the simultaneous reduction of GO and Ag ions together with efficient dispersion of Ag nanoparticles on the surface of RGO sheets. This simple and fast synthesis route is carried out at ambient conditions without using any additional chemical reducing agents, which has the potential to provide new avenues for the green fabrication of various RGO-based nanomaterials. Additionally, the RGO-DNA-Ag nanohybrids can be utilized as a novel sensing interfacial for direct determination of iodide by simple differential pulse voltammetry (DPV), without requiring any preceding preconcentration of the analyte. Based on the RGO-DNA-Ag nanohybrids modified electrode, a wide linear range of 1μM-1mM and a low detection limit of 0.2μM were obtained. This sensitive and direct method of analysis can be applied successfully to the determination of iodide in real samples.

Multiplexed ratiometric photoluminescent detection of pyrophosphate using anisotropic boron-doped nitrogen-rich carbon rugby ball-like nanodots

The shape of nanoparticles is decisive for their intrinsic physicochemical properties, as well as for the anisotropic behavior of individual particles in many instances. Herein, boron-doped nitrogen-rich carbon rugby ball-like nanodots (BNCRDs) have been synthesized by a heterophase polymerization route at a vital mass ratio of phenylboronic acid and uric acid in the precursor solution. Unexpectedly, the as-prepared BNCRDs showed stable dispersions of ellipsoidal carbonaceous polymer nanodots (rugby ball-like structures that are approximately 150 nm in length) as novel carbon dot derivatives. The anisotropic BNCRDs are water-soluble compounds that have highly enhanced photoluminescence (PL), which is accompanied by a large red shift of the emission peak upon the addition of Hg2+ and is nearly quenched upon the addition of Cu2+. This is due to the chelation-enhanced fluorescence property of the BNCRDs following Hg2+ complexation with sterically efficient heteroaromatics in the BNCRDs and the chelation enhancement quenching effect of the BNCRDs following Cu2+ complexation with the N/O donor atoms of the surface of the BNCRDs, respectively. Importantly, the BNCRD PL, which is changed by Hg2+ and Cu2+, exhibits high selectivity and sensitivity for the pyrophosphate ion (PPi) in the ranges 50 nM-280 μM and 10 nM-100 μM through a photoluminescent reset process, respectively, and could be attributed to the effective coordination/chelation interactions between Hg2+/Cu2+ and the plentiful oxygen groups of PPi. These results indicate that anisotropic BNCRDs can act not only as a ratiometric sensor for Hg2+ but also as a dual-mode PPi-selective sensor via ratiometric displacement and a competitive mechanism. With the broad diversity in the molecular backbone of the carbon dots via rich chemical routes, anisotropic BNCRDs have been developed with unique structural, electrical, and attractive functions, which greatly expands the research horizon of carbon-based composites.

Preparation of a silica stationary phase co-functionalized with Wulff-type phenylboronate and C12 for mixed-mode liquid chromatography

A silica stationary phase was designed and synthesized through the co-functionalization of silica with Wulff-type phenylboronate and C12 for mixed-mode liquid chromatography applications. The as-synthesized stationary phase was characterized by elemental analysis and Fourier Transform-InfraRed Spectroscopy (FT-IR). Retention mechanisms, including boronate affinity (BA), reversed-phase (RP) and anion-exchange (AE), were involved. Retention mechanism switching was easily realized by adjustment of the mobile phase constitution. Cis-diol compounds could be selectively captured under neutral conditions in BA mode and off-line separated in RP mode. Neutral, basic, acidic and amphiprotic compounds were chromatographed on the column in RP chromatography, while inorganic anions were chromatographed in AE chromatography to characterize the mixed-mode nature of the prepared stationary phase. In addition, the RP performance was compared with an octadecyl silica column in terms of column efficiency (N/m), asymmetry factor (Af), retention factor (k) and resolution (Rs). The prepared stationary phase offered multiple interactions with analytes in addition to hydrophobic interactions under RP elution conditions. Based on the mixed-mode properties, off-line 2D-LC, for selective capture and separation of urinary nucleosides, was successfully realized on a single column, demonstrating its powerful application potential for complex samples.

Bi2O2CO3 Nanosheets as Electrocatalysts for Selective Reduction of CO2 to Formate at Low Overpotential

Electrochemical reduction of carbon dioxide (CO2) to formate is energetically inefficient because a high overpotential (>1.0 V) is required for most traditional catalysts. In this work, Bi2O2CO3 (BOC) nanosheets were synthesized as electrocatalysts of CO2 reduction for the first time. Additionally, BOC decorated on the glassy carbon electrode was reduced in situ to metal Bi (RB) for comparing the catalytic performance toward CO2 reduction to that of BOC. The maximum faradaic efficiency of BOC was 83% at an overpotential of 0.59 V, which is a little lower than that of RB (90% obtained at the overpotential of 0.99 V). However, the overpotential for the reduction of CO2 to formate on BOC is obviously decreased compared to that on RB. After 27 h of electrolysis, approximately 80% formate selectivity was obtained using the BOC catalyst. According to the experimental results and the related literature, a new mechanism for the CO2 reduction reaction on BOC was proposed, which may play a guiding role in future catalyst design.

Hyperbranched Polyglycerol Functionalized Silica Stationary Phase for Hydrophilic Interaction Liquid Chromatography

Surface-initiated anionic-ring-opening multibranching polymerization was employed to prepare a hyperbranched polyglycerol (HPG) functionalized silica stationary phase for hydrophilic interaction liquid chromatography (HILIC). The obtained stationary phase was characterized by Fourier-transform infrared spectrometry (FT-IR) and thermogravimetric analysis (TGA). The chromatographic properties of the prepared stationary phase were systematically investigated. The abundance and multitude distribution of hydroxyl groups in HPG endowed the stationary phase with improved hydrophilicity and enhanced separation performance compared with the stationary phase functionalized with monolayer of hydroxyl groups. The stationary phase showed excellent retention of various polar compounds, such as nucleosides, necleobases, phenols and sulfanilamides, indicating great potential in the separation of complex biosamples.