Mesoporous silica-based electrochemical sensor for sensitive determination of environmental hormone bisphenol A

Electrochemical detection of honokiol and magnolol in traditional Chinese medicines using acetylene black nanoparticle-modified electrode

INTRODUCTION

Honokiol and magnolol are the active components of Magnolia officinalis, which is a widely used traditional Chinese medicine. Their simultaneous analysis is, therefore, important for the quality control of the product.

OBJECTIVE

To establish a simple, sensitive and rapid electrochemical method for the simultaneous detection of honokiol and magnolol based on the remarkable enhancement effect of acetylene black nanoparticle (AB).

METHODOLOGY

The AB-modified electrode was prepared via solvent evaporation. The electrochemical response of honokiol and magnolol was investigated using cyclic voltammetry. The simultaneous detection was performed with differential pulse voltammetry. The method was validated in terms of linearity, sensitivity, precision and accuracy.

RESULTS

The linear range for honokiol is 0.5-300 µg/L, and the limit of detection (LOD) is 0.25 µg/L (9.4 × 10(-10)  mol/L). For magnolol, the linear range is 10-250 µg/L, and the LOD is 5 µg/L (1.88 × 10(-8)  mol/L).

CONCLUSION

The new method was successfully used to determine honokiol and magnolol in a traditional Chinese medicine called Ageratum liquid.

Sensitivity and selectivity determination of BPA in real water samples using PAMAM dendrimer and CoTe quantum dots modified glassy carbon electrode

Bisphenol A (BPA) is an environmental pollutant to disrupt endocrine system or cause cancer, thus the detection of BPA is very important. Herein, an amperometric sensor was fabricated based on immobilized CoTe quantum dots (CoTe QDs) and PAMAM dendrimer (PAMAM) onto glassy carbon electrode (GCE) surface. The cyclic voltammogram of BPA on the sensor exhibited a well-defined anodic peak at 0.490V in 0.1M pH 8.0 PBS. The determination conditions were optimized and the kinetic parameters were calculated. The linear range was 1.3 x 10(-8) to 9.89 x 10(-6)M with the correlation coefficient of 0.9999. The limit of detection was estimated to be 1 x 10(-9)M. The current reached the steady-state current within about 5s. Furthermore, the fabricated sensor was successfully applied to determine BPA in real water samples.

Amperometric biosensor based on tyrosinase immobilized onto multiwalled carbon nanotubes-cobalt phthalocyanine-silk fibroin film and its application to determine bisphenol A

An amperometric bisphenol A (BPA) biosensor was fabricated by immobilizing tyrosinase on multiwalled carbon nanotubes (MWNTs)-cobalt phthalocyanine (CoPc)-silk fibroin (SF) composite modified glassy carbon electrode (GCE). In MWNTs-CoPc-SF composite film, SF provided a biocompatible microenvironment for the tyrosinase to retain its bioactivity, MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate and CoPc showed good electrocatalytic activity to electrooxidation of BPA. The cyclic voltammogram of BPA at this biosensor exhibited a well defined anodic peak at 0.625 V. Compared with bare GCE, the oxidation signal of BPA significantly increased; therefore, this oxidation signal was used to determine BPA. The effect factors were optimized and the electrochemical parameters were calculated. The possible oxidation mechanism was also discussed. Under optimum conditions, the oxidation current was proportional to BPA concentration in the range from 5.0 x 10(-8) to 3.0 x 10(-6) M with correlation coefficient of 0.9979 and detection limit of 3.0 x 10(-8) M (S/N=3). The proposed method was successfully applied to determine BPA in plastic products and the recovery was in the range from 95.36% to 104.39%.

Recent advances in nanostructured chemosensors and biosensors

Over the past few decades the fabrication of nanoscale materials for use in chemical sensing, biomedical and biological analyses has proven a promising avenue. Nanomaterials show promise in such chemical and biological analysis mainly due to their highly tunable size- and shape-dependent chemical and physical properties. Furthermore, they exhibit unique surface chemistry, thermal stability, high surface area and large pore volume per unit mass that can be exploited for sensor fabrication. This review will discuss the chemical and physical properties of nanomaterials necessary for use as chemosensors and biosensors. It will also highlight some noteworthy recent avenues using nanoscale materials as scaffolds for chemosensing and biosensing. Nanomaterials that have proven to be useful for the fabrication of sensors, as reviewed herein, have compositions including metals, metal oxides, chalcogenides and polymers. Their structures range from nanoparticles, nanorods, and nanowires to nanoporous and core-shells. Examples of the different types of structures and compositions as well as sensors and biosensors fabricated from them will be described. Some nanomaterials are functionalized with various kinds of ligands and bioactive groups to produce sensitive and selective sensors for specific analytes. The combination of two or more types of nanostructures with core-shell type nanoassemblies and other composite structures, in addition to advantageous features enhancing sensitivity and response time of related sensors, are also discussed.