Electrochemical Determination of Hazardous Herbicide Diuron Using MWCNTs-CS@NGQDs Composite-Modified Glassy Carbon Electrodes

Diuron (DU) abuse in weed removal and shipping pollution prevention always leads to pesticide residues and poses a risk to human health. In the current research, an innovative electrochemical sensor for DU detection was created using a glassy carbon electrode (GCE) that had been modified with chitosan-encapsulated multi-walled carbon nanotubes (MWCNTs-CS) combined with nitrogen-doped graphene quantum dots (NGQDs). The NGQDs were prepared by high-temperature pyrolysis, and the MWCNTs-CS@NGQDs composite was further prepared by ultrasonic assembly. TEM, UV-Vis, and zeta potential tests were performed to investigate the morphology and properties of MWCNTs-CS@NGQDs. CV and EIS measurements revealed that the assembly of MWCNTs and CS improved the electron transfer ability and effective active area of MWCNTs. Moreover, the introduction of NGQDs further enhanced the detection sensitivity of the designed sensor. The MWCNTs-CS@NGQDs/GCE electrochemical sensor exhibited a wide linear range (0.08~12 μg mL-1), a low limit of detection (0.04 μg mL-1), and high sensitivity (31.62 μA (μg mL-1)-1 cm-2) for DU detection. Furthermore, the sensor demonstrated good anti-interference performance, reproducibility, and stability. This approach has been effectively employed to determine DU in actual samples, with recovery ranges of 99.4~104% in river water and 90.0~94.6% in soil. The developed electrochemical sensor is a useful tool to detect DU, which is expected to provide a convenient and easy analytical technique for the determination of various bioactive species.

Advances in Chicken IgY-Based Immunoassays for the Detection of Chemical and Biological Hazards in Food Samples

As antibodies are the main biological binder for hazards in food samples, their performance directly determines the sensitivity, specificity, and reproducibility of the developed immunoassay. The overwhelmingly used mammalian-derived antibodies usually suffer from complicated preparation, high cost, frequent bleeding of animals, and sometimes low titer and affinity. Chicken yolk antibody (IgY) has recently attracted considerable attention in the bioanalytical field owing to its advantages in productivity, animal welfare, comparable affinity, and high specificity. However, a broad understanding of the application of IgY-based immunoassay for the detection of chemical and biological hazards in food samples remains limited. Here, we briefly summarized the diversity, structure, and production of IgY including polyclonal and monoclonal formats. Then, a comprehensive overview of the principles, designs, and applications of IgY-based immunoassays for these hazards was reviewed and discussed, including food-borne pathogens, food allergens, veterinary drugs, pesticides, toxins, endocrine disrupting chemicals, etc. Thus, the trend of IgY-based immunoassays is expected, and more IgY types, higher sensitivity, and diversification of recognition-to-signal manners are necessary in the future.

Plasmon-enhanced optical sensors: a review

Surface plasmon resonance (SPR) has found extensive applications in chemi-sensors and biosensors. Plasmons play different roles in different types of optical sensors. SPR transduces a signal in a colorimetric sensor through shifts in the spectral position and intensity in response to external stimuli. SPR can also concentrate the incident electromagnetic field in a nanostructure, modulating fluorescence emission and enabling plasmon-enhanced fluorescence to be used for ultrasensitive detection. Furthermore, plasmons have been extensively used for amplifying a Raman signal in a surface-enhanced Raman scattering sensor. This paper presents a review of recent research progress in plasmon-enhanced optical sensing, giving emphasis on the physical basis of plasmon-enhanced sensors and how these principles guide the design of sensors. In particular, this paper discusses the design strategies for nanomaterials and nanostructures to plasmonically enhance optical sensing signals, also highlighting the applications of plasmon-enhanced optical sensors in healthcare, homeland security, food safety and environmental monitoring.

Stereospecific recognition and quantitative structure–activity relationship between antibodies and enantiomers: ofloxacin as a model hapten

In this study, ofloxacin stereoisomers were chosen as a simple model to investigate the stereospecific recognition of chiral haptens and antibodies.

A plasmon-assisted fluoro-immunoassay using gold nanoparticle-decorated carbon nanotubes for monitoring the influenza virus

A plasmon-assisted fluoro-immunoassay (PAFI) was developed for the detection of the influenza virus by using Au nanoparticle (Au NP)-decorated carbon nanotubes (AuCNTs) that were synthesized using phytochemical composites at room temperature in deionized water. Specific antibodies (Abs) against the influenza virus were conjugated onto the surface of AuCNTs and cadmium telluride quantum dots (QDs), which had a photoluminescence intensity that varied as a function of virus concentration and a detection limit of 0.1 pg/mL for all three types of influenza viruses examined. The clinically isolated influenza viruses (A/Yokohama/110/2009 (H3N2)) were detected in the range of 50-10,000 PFU/mL, with a detection limit of 50 PFU/mL. From a series of proof-of-concept and clinical experiments, the developed PAFI biosensing system provided robust signal production and enhancement, as well as an excellent selectivity and sensitivity for influenza viruses. This nanoparticle-based technique could be potentially developed as an efficient detection platform for the influenza virus.

Nanobioprobe mediated DNA aptamers for explosive detection

Specific nucleic acid aptamers using the microtiter plate based modified SELEX method against explosive trinitrotoluene are reported. Efficient partitioning of dsDNA was carried out using streptavidin labeled gold nanoprobes for the selection of specific aptamers. The selected binders having an affinity of ~10(-7) M were used in the newly developed electrochemical aptasensor, exhibiting a detection limit of around 1 ppb for trinitrotoluene.