Affinity interactions between phenylboronic acid-carrying self-assembled monolayers and flavin adenine dinucleotide or horseradish peroxidase

A method is provided for the recognition of glycated molecules based on their binding affinities to boronate-carrying monolayers. The affinity interaction of flavin adenine dinucleotide (FAD) and horseradish peroxidase (HRP) with phenylboronic acid monolayers on gold was investigated by using voltammetric and microgravimetric methods. Conjugates of 3-aminophenylboronic acid and 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) or 11-mercaptoundecanoic acid were prepared and self-assembled on gold surfaces to generate monolayers. FAD is bound to this modified surface and recognized by a pair of redox peaks with a formal potential of -0.433 V in a 0.1 M phosphate buffer solution, pH 6.5. Upon addition of a sugar to the buffer, the bound FAD could be replaced, indicating that the binding is reversible. Voltammetric, mass measurements, and photometric activity assays show that the HRP can also be bound to the interface. This binding is reversible, and HRP can be replaced by sorbitol or removed in acidic solution. The effects of pH, incubation time, and concentration of H(2)O(2) were studied by comparing the catalytic reduction of H(2)O(2) in the presence of the electron-donor thionine. The catalytic current of the HRP-loaded electrode was proportional to HRP concentrations in the incubation solution in the range between 5 microg mL(-1) and 0.1 mg mL(-1) with a linear slope of 3.34 microA mL mg(-1) and a correlation coefficient of 0.9945.     

Selective collection and detection of MCF-7 breast cancer cells using aptamer-functionalized magnetic beads and quantum dots based nano-bio-probes

A novel strategy for selective collection and detection of breast cancer cells (MCF-7) based on aptamer–cell interaction was developed. Mucin 1 protein (MUC1) aptamer (Apt1) was covalently conjugated to magnetic beads to capture MCF-7 cell through affinity interaction between Apt1 and MUC1 protein that overexpressed on the surface of MCF-7 cells. Meanwhile, a nano-bio-probe was constructed by coupling of nucleolin aptamer AS1411 (Apt2) to CdTe quantum dots (QDs) which were homogeneously coated on the surfaces of monodispersed silica nanoparticles (SiO₂ NPs). The nano-bio-probe displayed similar optical and electrochemical performances to free CdTe QDs, and remained high affinity to nucleolin overexpressed cells through the interaction between AS1411 and nucleolin protein. Photoluminescence (PL) and square-wave voltammetric (SWV) assays were used to quantitatively detect MCF-7 cells. Improved selectivity was obtained by using these two aptamers together as recognition elements simultaneously, compared to using any single aptamer. Based on the signal amplification of QDs coated silica nanoparticles (QDs/SiO₂), the detection sensitivity was enhanced and a detection limit of 201 and 85 cells mL⁻¹ by PL and SWV method were achieved, respectively. The proposed strategy could be extended to detect other cells, and showed potential applications in cell imaging and drug delivery.     

The Fe-N-C Nanozyme with Both Accelerated and Inhibited Biocatalytic Activities Capable of Accessing Drug–Drug Interactions

Emerging as a cost-effective and robust enzyme mimic, nanozymes have drawn increasing attention with broad applications ranging from cancer therapy to biosensing. Developing nanozymes with both accelerated and inhibited biocatalytic properties in a biological context is intriguing to peruse more advanced functions of natural enzymes, but remains challenging, because most nanozymes are lack of enzyme-like molecular structures. By re-visiting and engineering the well-known Fe-N-C electrocatalyst that has a heme-like Fe-N_x active sites, herein, it is reported that Fe-N-C could not only catalyze drug metabolization but also had inhibition behaviors similar to cytochrome P450 (CYP), endowing it a potential replacement of CYP for preliminary evaluation of massive potential chemicals, drug dosing guide, and outcome prediction. In addition, in contrast to electrocatalysts, the highly graphitic framework of Fe-N-C may not be obligatory for a competitive CYP-like activity.     

The Fe‐N‐C Nanozyme with Both Accelerated and Inhibited Biocatalytic Activities Capable of Accessing Drug–Drug Interactions

Emerging as a cost‐effective and robust enzyme mimic, nanozymes have drawn increasing attention with broad applications ranging from cancer therapy to biosensing. Developing nanozymes with both accelerated and inhibited biocatalytic properties in a biological context is intriguing to peruse more advanced functions of natural enzymes, but remains challenging, because most nanozymes are lack of enzyme‐like molecular structures. By re‐visiting and engineering the well‐known Fe‐N‐C electrocatalyst that has a heme‐like Fe‐N_x active sites, herein, it is reported that Fe‐N‐C could not only catalyze drug metabolization but also had inhibition behaviors similar to cytochrome P450 (CYP), endowing it a potential replacement of CYP for preliminary evaluation of massive potential chemicals, drug dosing guide, and outcome prediction. In addition, in contrast to electrocatalysts, the highly graphitic framework of Fe‐N‐C may not be obligatory for a competitive CYP‐like activity.     

Nitrite reduction and detection at a carbon paste electrode containing hemoglobin and colloidal gold

A novel renewable reagentless nitrite biosensor based on the direct electron transfer of hemoglobin (Hb) and a new sensing mechanism was proposed by combining the advantageous features of colloidal gold nanoparticle and carbon paste technology. The direct electrochemistry of immobilized Hb displayed a pair of redox peaks with a formal potential of -42 mV (vs. NHE) in 0.2 mol dm(-3) NaAc-HAc buffer (pH 5.5). The immobilized Hb displayed an excellent response to the reduction of NO2(-) with one interfacial charge transfer followed by a chemical reaction (EC) mechanism. Under optimal conditions, the interfacial EC process could be used for the sensitive determination of NO2(-) with a linear range from 0.1 to 9.7 micromol dm(-3) and a detection limit of 0.06 [micro sign]mol dm(-3) at 3sigma. The amperometric determination of high concentrations of NO2(-) based on the irreversible reduction of NO could be performed at pH 4.0 with a linear range from 0.1 to 1.2 mmol dm(-3). The surface of biosensor could be renewed quickly and reproducibly by a simple polish step. The biosensor has been used satisfactorily for nitrite determination in native water samples.     

Phenylboronic acid immunoaffinity reactor coupled with flow injection chemiluminescence for determination of α-fetoprotein

A reusable and sensitive immunoassay based on phenylboronic acid immunoaffinity reactor in combination with flow injection chemiluminescence (CL) for determination of glycoprotein was described. The reactor was fabricated by immobilizing 3-aminophenylboronic acid (APBA) on glass microbeads with γ-glycidoxypropyltrimethoxysilane (GPMS) as linkage. The α-fetoprotein (AFP) could be easily immobilized on the APBA coated beads through sugar-boronic interaction. After an off-line incubation, the mixture of the analyte AFP with horseradish peroxidase-labeled AFP antibody (HRP-anti-AFP) was injected into the reactor. This led the trapping of free HRP-anti-AFP by the surface coated AFP on glass beads. The trapped HRP-anti-AFP was detected by chemiluminescence due to its sensitizing effect on the reaction of luminol and hydrogen peroxide. Under optimal conditions, the chemiluminescent signal was proportional to AFP concentration in the range of 10-100 ng mL⁻¹. The whole assay process including regeneration of the reactor could be completed within 31 min. The proposed system showed acceptable detection and fabrication reproducibility, and the results obtained with the present method were in acceptable agreement with those from parallel single-analyte test of practical clinical sera. The described method enabled a low-cost, time saving and was potential to detect the serum AFP level in clinical diagnosis.     

Surface-initiated atom-transfer radical polymerization of 4-acetoxystyrene for immunosensing

A novel immunosensing strategy based on surface‐initiated atom‐transfer radical polymerization (SI‐ATRP) in combination with electrochemical detection is proposed. Specifically, 4‐acetoxystyrene (AS) has been chosen as a monomer for ATRP due to its ability to provide acetoxyl groups, which can be converted into phenolic hydroxyl groups for electrochemical detection in the presence of tyrosinase. A controlled radical polymerization reaction of 4‐acetoxystyrene at 60 °C was triggered after immobilization of initiator molecules on an electrode surface. The growth of long‐chain polymeric materials increased the concentration of phenolic hydroxyl groups, which in turn significantly enhanced the electrochemical signal output. Polymerization conditions, such as temperature and duration, monomer concentration, and the catalyst/monomer ratio have been optimized. The in situ surface‐initiated ATRP was confirmed by scanning electron microscope (SEM) images and X‐ray photoelectron spectroscopy (XPS) analysis. Cyclic voltammetric investigation revealed a pair of well‐defined oxidation and reduction peaks at 0.232 and 0.055 V, which corresponded to the redox behavior of catechol/o‐quinone on the electrode surface. The proposed approach has been successfully extended to immune recognition. A detection limit of 0.3 ng mL^?1 for rabbit immunoglobulin G (IgG) as a model antigen has been achieved. Despite the limited availability of the IgG antibody, this technology might also be expanded to the detection of other proteins and DNA.     

Direct Electrochemistry and Application in Electrocatalysis of Hemoglobin in a Polyacrylic Resin‐Gold Colloid Nanocomposite Film

A novel nanocomposite integrating the good biocompatibility of polyacrylic resin nanoparticles (PAR) and the good conductivity of colloidal gold nanoparticles was proposed to construct the matrix for the immobilization of hemoglobin (Hb) on the surface of a glassy carbon electrode (GCE). UV‐vis spectra demonstrated that Hb preserved its native structure after being entrapped into the composite film. The direct electrochemistry of hemoglobin (Hb) in this nanocomposite films showed a pair of well‐defined and quasi‐reversible cyclic voltammetric peaks with a formal potential of ?0.307 mV and a constant electron transfer rate of 2.51±0.2 s^?1. The resultant amperometric biosensor showed fast responses to the analytes with excellent detection limits of 0.2 µM for H₂O₂ and 0.89 µM for TCA (S/N=3), and high sensitivity of 1108.6 for H₂O₂ and 77.14 mA cm^?2 M^?1 for TCA, respectively. The linear current response was found in the range from 0.59 to 7.3 µM (R²=0.9996) for H₂O₂ and from 5 to 85 µM (R²=0.9996) for TCA, while the superior apparent Michaelis–Menten constant was 0.012 mM for H₂O₂ and 0.536 mM for TCA, respectively. Therefore, the PAR‐Au‐Hb nanocomposite as a novel matrix opens up a possibility for further study on the direct electrochemistry of other proteins.     

试论高校科技产业的管理体制与运行机制

该文在分析高校科技产业现状的基础上,提出了高校科技产业管理体制的构思与运行机制的设想.