Detection of atrazine based on the SPR determination of P450 mRNA levels in Saccharomyces cerevisiae

A Novel Magnetoelastic Nanobiosensor for Highly Sensitive Detection of Atrazine

Here, we firstly report a wireless magnetoelastic (ME) nanobiosensor, based on ME materials and gold nanoparticles (AuNPs), for highly sensitive detection of atrazine employing the competitive immunoassay. In response to a time-varying magnetic field, the ME material longitudinally vibrates at its resonance frequency which can be affected by its mass loading. The layer of AuNPs coating on the ME material contributes to its biocompatibility, stability, and sensitivity. The atrazine antibody was oriented immobilized on the AuNPs-coated ME material surface through protein A, improving the nanobiosensor's performance. Atomic force microscope (AFM) analysis proved that the immobilization of atrazine antibody was successful. Furthermore, to enhance the sensitivity, atrazine-albumin conjugate (Atr-BSA) was induced to compete with atrazine for binding with atrazine antibody, amplifying the signal response. The resonance frequency shift is inversely and linearly proportional to the logarithm of atrazine concentrations ranging from 1 ng/mL to 100 μg/mL, with the sensitivity of 3.43 Hz/μg mL-1 and the detection limit of 1 ng/mL, which is significantly lower than the standard established by US Environmental Protection Agency (EPA). The experimental results indicated that the ME nanobiosensor displayed strong specificity and stability toward atrazine. This study provides a new convenient method for rapid, selective, and highly sensitive detection of atrazine, which has implications for its applications in water quality monitoring and other environmental detection fields.

Direct optical measurements of far- and deep-ultraviolet surface plasmon resonance with different refractive indices

The surface plasmon resonance (SPR) of Al thin films was investigated by varying the refractive index of the environment near the films in the far-ultraviolet (FUV, 120-200 nm) and deep-ultraviolet (DUV, 200-300 nm) regions. An original FUV-DUV spectrometer that adopts an attenuated total reflectance (ATR) system was used. The measurable wavelength range was down to the 180 nm, and the environment near the Al surface could be controlled. The resultant spectra enabled the dispersion relationship of Al-SPR in the FUV and DUV regions to be obtained. In the presence of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) on the Al film, the angle and wavelength of the SPR became larger and longer, respectively, compared to those in air. These shifts correspond well with the results of simulations performed using Fresnel equations.

Oligonucleotide-based label-free detection with optical microresonators: strategies and challenges

This review targets diversified oligonucleotide-based biodetection techniques, focusing on the use of microresonators of whispering gallery mode (WGM) type as optical biosensors mostly integrated with lab-on-a-chip systems. On-chip and microfluidics combined devices along with optical microresonators provide rapid, robust, reproducible and multiplexed biodetection abilities in considerably small volumes. We present a detailed overview of the studies conducted so far, including biodetection of various oligonucleotide biomarkers as well as deoxyribonucleic acids (DNAs), ribonucleic acids (RNAs) and proteins. We particularly advert to chemical surface modifications for specific and selective biosensing.

Optical nano antennas: state of the art, scope and challenges as a biosensor along with human exposure to nano-toxicology

The concept of optical antennas in physical optics is still evolving. Like the antennas used in the radio frequency (RF) regime, the aspiration of optical antennas is to localize the free propagating radiation energy, and vice versa. For this purpose, optical antennas utilize the distinctive properties of metal nanostructures, which are strong plasmonic coupling elements at the optical regime. The concept of optical antennas is being advanced technologically and they are projected to be substitute devices for detection in the millimeter, infrared, and visible regimes. At present, their potential benefits in light detection, which include polarization dependency, tunability, and quick response times have been successfully demonstrated. Optical antennas also can be seen as directionally responsive elements for point detectors. This review provides an overview of the historical background of the topic, along with the basic concepts and parameters of optical antennas. One of the major parts of this review covers the use of optical antennas in biosensing, presenting biosensing applications with a broad description using different types of data. We have also mentioned the basic challenges in the path of the universal use of optical biosensors, where we have also discussed some legal matters.

Surface plasmon resonance sensing of nucleic acids: a review

Biosensors based on surface plasmon resonance (SPR) have become a central tool for the investigation and quantification of biomolecules and their interactions. Nucleic acids (NAs) play a vital role in numerous biological processes and therefore have been one of the major groups of biomolecules targeted by the SPR biosensors. This paper discusses the advances of NA SPR biosensor technology and reviews its applications both in the research of molecular interactions involving NAs (NA-NA, NA-protein, NA-small molecule), as well as for the field of bioanalytics in the areas of food safety, medical diagnosis and environmental monitoring.

Applications of microbial cell sensors

Since the first microbial cell sensor was studied by Karube et al. in 1977, many types of microbial cell sensors have been developed as analytical tools. The microbial cell sensor utilizes microbes as a sensing element and a transducer. The characteristics of microbial cell sensors as sensing devices are a complete contrast to those of enzyme sensors or immunosensors, which are highly specific for the substrates of interest, although the specificity of the microbial cell sensor has been improved by genetic modification of the microbe used as the sensing element. Microbial cell sensors have the advantages of tolerance to measuring conditions, a long lifetime, and good cost performance, and have the disadvantage of a long response time. In this review, applications of microbial cell sensors are summarized.

Development of microbial sensors and their application

Many types of microbial sensors have been developed as analytical tools since the first microbial sensor was studied by Karube et al. in 1977. The microbial sensor consists of a transducer and microbe as a sensing element. The characteristics of the microbial sensors are a complete contrast to those of enzyme sensors or immunosensors, which are highly specific for the substrates of interest, although the specificity of the microbial sensor has been improved by genetic modification of the microbe used as the sensing element. Microbial sensors have the advantages of tolerance to measuring conditions, a long lifetime, and cost performance, and also have the disadvantage of a long response time. In this review, the long history of microbial sensor development is summarized.

Part per trillion determination of atrazine in natural water samples by a surface plasmon resonance immunosensor

A new immunoassay for continuously monitoring atrazine in water has been developed. It uses a portable biosensor platform based on surface plasmon resonance (SPR) technology. This immunoassay is based on the binding inhibition format with purified polyclonal antibodies, with the analyte derivative covalently immobilized on a gold sensor surface. An alkanethiol self-assembled monolayer (SAM) was formed on the gold-coated sensor surface in order to obtain a reusable sensing surface. The low detection limit for the optimized assay, calculated as the concentration that produces a 10% decrease in the blank signal, is 20 ng/L. A complete assay cycle, including regeneration, is accomplished in 25 min. Additionally, a study of the matrix effects of different types of wastewater was performed. All measurements were carried out with the SPR sensor system (beta-SPR) commercialised by the company Sensia, S.L. (Spain). The small size and low response time of the beta-SPR platform would allow it to be used in real contaminated locations. The immunosensor was evaluated and validated by measuring the atrazine content of 26 natural samples collected from Ebro River. Solid-phase extraction followed by gas chromatography coupled to mass spectrometric detection (SPE-GC-MS) was used to validate the new immunoassay.

Survey of the year 2000 commercial optical biosensor literature

We have compiled a comprehensive list of the articles published in the year 2000 that describe work employing commercial optical biosensors. Selected reviews of interest for the general biosensor user are highlighted. Emerging applications in areas of drug discovery, clinical support, food and environment monitoring, and cell membrane biology are emphasized. In addition, the experimental design and data processing steps necessary to achieve high-quality biosensor data are described and examples of well-performed kinetic analysis are provided.

Detection of toxic chemicals with high sensitivity by measuring the quantity of induced P450 mRNAs based on surface plasmon resonance

In this study we describe a novel sensor system to detect toxic chemicals based on measurement of the quantity of Saccharomyces cerevisiae P450 mRNAs induced by them. Detection was conducted using a flow-injection-type sensor system based on surface plasmon resonance (SPR). The DNA and peptide nucleic acid (PNA) probes containing a complementary sequence to a part of P450 mRNA were immobilized on the sensor chip and the P450 mRNAs hybridized to the probes were quantified. We succeeded in detecting 10 ng/L (10 ppt) of atrazine using both DNA and PNA probes. Using this sensor system, we were able to detect bisphenol A in addition to atrazine. Furthermore, we achieved higher sensitivity by amplifying the target P450 mRNA based on nucleic acid sequence-based amplification (NASBA). This method allows for sensitive, rapid, and easy detection of some toxic chemicals.