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The detection of biomarkers with both high sensitivity and specificity is crucial for the diagnosis and treatment of related diseases. However, many current detections employ ex-situ detection method and non-confined condition, thus have many problems, which may eventually lead to inaccurate detection results. Compared to detection in non-confined space, detection in confined space can better reflect the real in-vivo situation. Therefore, the construction of detection for target molecules in confined space has great significance for both theoretical research and practical application. To realize the detection of target molecules in confined space, the probes should accurately enter the confined space where the target molecules reside and interact with the interface. Thus, how to explore and utilize the properties of the interface (for example, bioinspired superwettability) has always been a hot and difficult topic in this field. Herein, the recent advances and our efforts in recent 10 years on detection of bio-target molecules in confined space with superwettable interface have been introduced from the perspective of the detection methods. The suitable and most widely employed detection methods for target molecules in confined spaces are introduced firstly. Then, recent progresses for related detections based on visual, optical, and electrochemical detection methods are presented successively. Finally, the perspective for detection in confined space is discussed for the future development of biochemical detection. [ABSTRACT FROM AUTHOR]

Longitudinal giant magnetoimpedance effect of [Fe21Ni79/Cu]5/Cu/[Fe21Ni79/Cu]5 film element was investigated depends on stray magnetic field of epoxy magnetic composite with 30% weight concentration of iron oxide magnetic microparticles. Configuration of an experiment was a model of thrombus detection in a blood vessel. Stray magnetic field was varied by movement of a magnetic composite above the element perpendicular to the long side. Composite was either magnetized or not to the state of remanence. As the magnetic composite approaches the GMI element, MI ratio curves are smoothed and shifted along the field axis and maximum value of the MI ratio decreases. Magnetic properties of magnetic composite and film element were investigated as well. [ABSTRACT FROM AUTHOR]

The dependence of a longitudinal giant magnetoimpedance (GMI) effect of a [Fe21Ni79/Cu]5/Cu/[Fe21Ni79/Cu]5 film element on the position of a magnetic insert is investigated in a model experiment on detecting a clot in a blood vessel. The magnetic insert is an epoxy composite containing 30 wt.% of the iron oxide microparticles. An investigation of the magnetic properties of the film element and the magnetic composite cylinder-shaped sample is performed. The magnetic insert is placed at a distance of 1.1 mm above the film surface and can be displaced perpendicular to its longer side with a step of 1 mm. As soon as the magnetic insert approaches the element, the maximum value of magnetoimpedance (MI) ratio for resistance is observed to decrease, and there is a shift of the curves of the MI ratio for resistance along the external magnetic field lines. The magnetic stray fields influencing the film in each position of the magnetic insert are simulated with the Comsol software and compared with the GMI response. [ABSTRACT FROM AUTHOR]

This study reports the synthesis and characterization of the red nanophosphors Zn2SiO4:Eu3+ (ZSO:Eu3+) and Mg2TiO4:Mn4+ (MTO:Mn4+). The use of phosphors as a fluorescence label for lateral flow immunochromatographic assay (LFIA) has also been described. The optimal photoluminescence (PL) for ZSO:Eu3+ was obtained when it was synthesized with 7 mol% of Eu3+ and annealed at 1100 °C for 1 h. Long fluorescence lifetime (1.01 ms), high activation energy E a (0.28 eV), and low PL degeneration (10% at 110 °C) are the characteristics of ZSO:Eu3+. MTO:Mn4+ also exhibited high PL intensity along with a high Ea of 0.32 eV. The emission wavelengths of phosphors are biocompatible with the optical bio-window of tissues. When human immunoglobulin G (human IgG) at a constant concentration of 100 μg/mL was used for detection, the PL ratios of the test line to the control line were 2.15 and 2.28 for the ZSO:Eu3+- and MTO:Mn4+-labeled LFIA, respectively. Thus, the ZSO:Eu3+ and MTO:Mn4+ nanophosphors are capable of human IgG recognition and are the promising candidates as fluorescent labels for on-site rapid optical biodetection. [ABSTRACT FROM AUTHOR]

Dioxins are the most toxic known environmental pollutants and are mainly formed by human activities. Due to their structural stability, dioxins persist for extended periods and can be transported over long distances from their emission sources. Thus, dioxins can be accumulated to considerable levels in both human and animal food chains. Along with sediments, soils are considered the most important reservoirs of dioxins. Soil microorganisms are therefore highly exposed to dioxins, leading to a range of biological responses that can impact the diversity, genetics and functional of such microbial communities. Dioxins are very hydrophobic with a high affinity to lipidic macromolecules in exposed organisms, including microbes. This review summarizes the genetic, molecular and biochemical impacts of dioxins on the lipid metabolism of soil microbial communities and especially examines modifications in the composition and architecture of cell membranes. This will provide a useful scientific benchmark for future attempts at soil ecological risk assessment, as well as in identifying potential dioxin-specific-responsive lipid biomarkers. Finally, potential uses of lipid-sequestering microorganisms as a part of biotechnological approaches to the bio-management of environmental contamination with dioxins are discussed. [ABSTRACT FROM AUTHOR]

Detection of a single base mutation in Mycobacterium tuberculosis DNA can provide fast and highly specific diagnosis of antibiotic-resistant tuberculosis. Mutation-specific ligation of padlock probes (PLPs) on the target followed by rolling circle amplification (RCA) is highly specific, but challenging to integrate in a simple microfluidic device due to the low temperature stability of the phi29 polymerase and the interference of phi29 with the PLP annealing and ligation. Here, we utilized the higher operation temperature and temperature stability of Equiphi29 polymerase to simplify the integration of the PLP ligation and RCA steps of an RCA assay in two different strategies performed at uniform temperature. In strategy I, PLP annealing took place off-chip and the PLP ligation and RCA were performed in one pot and the two reactions were clocked by a change of the temperature. For a total assay time of about 1.5 h, we obtained a limit of detection of 2 pM. In strategy II, the DNA ligation mixture and the RCA mixture were separated into two chambers on a microfluidic disc. After on-disc PLP annealing and ligation, the disc was spun to mix reagents and initiate RCA. For a total assay time of about 2 h, we obtained a limit of detection of 5 pM. [ABSTRACT FROM AUTHOR]

A colorimetric assay is described for simultaneous detection of multiple analytes related to food safety. It is based on the use of a sandwich aptasensor and terminal deoxynucleotidyl transferase (TdT) which produces a primer for subsequent rolling circle amplification (RCA). Two split aptamer fragments (Apt1 and Apt2) are firstly immobilized, Apt1 on gold nanoparticles (AuNPs), and Apt2 on magnetic beads (MBs). They are then used in a sandwich aptasensor. In the presence of analyte, two probes could specifically recognize target and form a ternary assembly, and the magnetic beads also act to separate rapidly and enrich the target. Then, the extension of template-free DNA is triggered by TdT at the exposed 3′-hydroxy terminals of Apt1. This produces polyA sequences that serve as primers for subsequent RCA. The product of RCA is hybridized with a complementary horse radish peroxidase (HRP) DNA probe. HRP catalyzes the H2O2-mediated oxidation of tetramethylbenzidine (TMB) and forms a blue chromogenic product. After magnetic separation, the absorption values of the blue product in the supernatant are measured at a wavelength of 600 nm. Based on this dual amplification mechanism, the assay was applied to multiplexed determination of enrofloxacin (ENR), lead(II), Escherichia coli O157:H7 and tropomyosin. Exemplarily, ENR is detectable at concentrations down to 2.5 pg mL−1 with a linear range that extends from 1 pg mL−1 to 1 μg·mL−1. The assay was validated by analysis of spiked fish samples. Recoveries range between 87.5 and 92.1%. [ABSTRACT FROM AUTHOR]

Although a variety of whole-cell biosensors and biosorbents have been developed for detection and removal of heavy metal contaminants, few whole cells can be applied to both monitoring and remediation of copper pollution in water. In this study, a modified plasmid was constructed by incorporating a copper-sensing element and a copper-adsorbing element into a temperature-inducible plasmid, pBV220. This plasmid was subsequently transformed into an engineered Escherichia coli strain lacking copA and cueO. This dual-functional E. coli cell selectively responded to copper ions with a linear detection range of 0.01–25 μM at 37 °C and could express surface-displayed CueR when treated at 42 °C without any costly chemical inducers. The display of CueR on the cell surface specifically enhanced its copper adsorption capacity and rapidly removed copper ions from aqueous solutions. In addition, the CueR surface-displayed cells could be regenerated by adsorption-desorption cycles via pH regulation. Moreover, by simply using two different temperatures, the detection or adsorption of copper using this dual-functional whole cell was achieved without any cross-interference. Most importantly, it provided highly sensitive, accurate quantification, and effective removal of copper in real environmental water samples. Thus, this E. coli cell can be used for large-scale detection and remediation of copper pollutants. [ABSTRACT FROM AUTHOR]

Bacterial cell immobilization is a novel technique used in many areas of biosciences and biotechnology. Iron oxide nanoparticles have attracted much attention in bacterial cell immobilization due to their unique properties such as superparamagnetism, large surface area to volume ratio, biocompatibility and easy separation methodology. Adhesion is the basis behind many immobilization techniques and various types of interactions determine bacterial adhesion. Efficiency of bacterial cell immobilization using iron oxide nanoparticles (IONs) generally depends on the physicochemical properties of the IONs and surface properties of bacterial cells as well as environmental/culture conditions. Bacteria exhibit various metabolic responses upon interaction with IONs, and the potential applications of iron oxide nanoparticles in bacterial cell immobilization will be discussed in this work. [ABSTRACT FROM AUTHOR]

The use of in vitro assays for the biodetection of endocrine active substances (EAS) aims to reduce and replace in vivo studies required for regulatory assessment. However, this approach often fails to take into account the role of biotransformation on the activity of the test substances. A method introducing an S9 metabolic system into the CALUX-reporter gene assays for estrogen receptor α- and anti-androgen receptor-mediated activities was developed. Methoxychlor, which exhibits increased estrogenic and anti-androgenic activities after biotransformation, was used to establish the method in ERα and anti-AR CALUX. For the anti-androgenic assay, stanozolol was used as a competing agonist not metabolized by S9. The method was first applied in both agonist and antagonist modes to methoxychlor and bisphenol A, as positive and negative controls, respectively. Then, benzo(a)pyrene and flutamide were also tested for their bioactivation potential. Co-treatment with S9 successfully increased the ERα agonist and AR antagonist potency of methoxychlor; no change was observed for bisphenol A. Incubation with S9 also enhanced the anti-androgenic activity of flutamide. Interestingly, the metabolism of benzo(a)pyrene by S9 resulted in a greatly increased estrogen receptor-mediated transcriptional activation, while the shift in EC50 was only minor. It is likely that both enzyme kinetics and metabolite stability affect the composition of the final metabolite mixture and thus influence the observed effects. Together these results demonstrate the relevance of including biotransformation in in vitro bioassays for the detection of EAS. [ABSTRACT FROM AUTHOR]

In this study, a new approach for the preparation of a fluorescent europium(III) complex-doped silica nanoparticles has been developed. The synthesis process involved the following steps: (1) preparing silica nanoparticles by water-in-oil microemulsion method, (2) dyeing the spherical silica particles by europium(III): naphtoyltrifluoroacetone (NTA):trioctylphosphineoxide (TOPO), (3) adsorbing polyvinylpyrrolidone (PVP) onto the core structure and growing silica on PVP surface. The as-prepared nanoparticles exhibited stronger emission intensity, higher photo- and chemical stability. Despite the fact that europium(III) complex was doped into the nanoparticles, its fluorescence properties such as a wide Stokes shift, a narrow emission peak, and long fluorescence lifetime, were retained. The nanoparticles are uniform in shape and size (50 ± 5 nm in diameter). This study could provide new avenue for the fabrication of Eu: NTA:TOPO-based nanoparticles, facilitating their application in bioassay issues. [ABSTRACT FROM AUTHOR]

We explore a new calibration-free approach to biodetection based on whispering gallery modes (WGMs) without a reference measure and relative shifts. Thus, the requirement to keep track of the sensor position is removed, and a freely moving population of fluorophore-doped polystyrene microspheres can now fulfill this role of sensing resonator. Breaking free from fixed surface-based biosensing promotes adhesion between the microsphere sensors and the analytes since both can now be thoroughly mixed. The 70-nm-wide spectrum of green fluorescent microbeads allows us to monitor over 20 WGMs simultaneously without needing evanescent light coupling into the microspheres, hence enabling remote sensing. Since the exact radius of each microsphere is unknown a priori, it requires algorithmic analyses to obtain a reliable result for the refractive index of a solution. We first test our approach with different solutions of alcohol in water obtaining 3 × 10−4 precision on the refractive index at lower concentrations. Then, the solutions of bacterial spores in water yield clear evidence of biodetection in the statistical analysis of WGMs from 50 microspheres. To extend the fluorescence spectral range of our WGM sensors, we present preliminary results on coating microspheres with CdSe/ZnS quantum dots. [ABSTRACT FROM AUTHOR]

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