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One‐dimensional zinc oxide nanomaterials (1DZnO) have emerged as promising, cost‐effective nanoplatforms with adjustable properties suitable for electrochemical and optical biosensing applications. In this work, modifications in the inherent photoluminescent response of 1DZnO are harnessed to develop a novel immunosensor tailored for detecting enteropathogenic Escherichia coli. This nanobiosensor demonstrates a modulation in photoluminescence signal, effectively responsive to analyte concentrations ranging from 1 × 102 to 1 × 108 CFU mL−1, with direct visualization of targeted bacterial cells over 1DZnO structures through scanning electron microscopy. The conceptualization of this nanobiosensor is focused on a real‐time contact strategy that can significantly reduce processing and response times for pathogen detection, prospected for emergency scenarios. With this aim, the detection process unfolds in real time, with a mere 5–10 s interaction time, corroborated by the standard polymerase chain reaction approach. This synergistic validation underscores the reliability and precision of the developed biosensor. Notably, the utility of 1DZnO nanoplatforms extends beyond the realm of enteropathogenic E. coli, as the biosensing performance exhibited here holds promise for analogous applications involving other medically pertinent pathogens. This study paves the way for the broader implementation of 1DZnO‐based biosensors in medical diagnostics, offering rapid, sensitive, and real‐time detection capabilities. [ABSTRACT FROM AUTHOR]

One‐dimensional zinc oxide nanomaterials (1DZnO) have emerged as promising, cost‐effective nanoplatforms with adjustable properties suitable for electrochemical and optical biosensing applications. In this work, modifications in the inherent photoluminescent response of 1DZnO are harnessed to develop a novel immunosensor tailored for detecting enteropathogenic Escherichia coli. This nanobiosensor demonstrates a modulation in photoluminescence signal, effectively responsive to analyte concentrations ranging from 1 × 102 to 1 × 108 CFU mL−1, with direct visualization of targeted bacterial cells over 1DZnO structures through scanning electron microscopy. The conceptualization of this nanobiosensor is focused on a real‐time contact strategy that can significantly reduce processing and response times for pathogen detection, prospected for emergency scenarios. With this aim, the detection process unfolds in real time, with a mere 5–10 s interaction time, corroborated by the standard polymerase chain reaction approach. This synergistic validation underscores the reliability and precision of the developed biosensor. Notably, the utility of 1DZnO nanoplatforms extends beyond the realm of enteropathogenic E. coli, as the biosensing performance exhibited here holds promise for analogous applications involving other medically pertinent pathogens. This study paves the way for the broader implementation of 1DZnO‐based biosensors in medical diagnostics, offering rapid, sensitive, and real‐time detection capabilities.

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]

After the first visible photoluminescence (PL) from porous silicon (pSi), continuous efforts are made to fabricate Si-based compound nanomaterials embedded in matrices such as oxide, nitride, and carbide to improve optical performance and industrial acceptability. These nanomaterials' functional and desired properties (nanoparticles and quantum dots embedded in matrices) can vary significantly when embedded in technologically relevant matrices. However, exploring the exact emission mechanisms is one of the remaining challenges from the past few decades. To cover this gap, this review discusses the morphological and optoelectronic properties of Si-based compound nanomaterials and their correlation with the quantum confinement effect and different surface states to find precise emission mechanisms. One of the biggest challenges of using silicon nanomaterials in the biological sector is the development of sensitive materials of low/acceptable toxicity for identifying target analytes either inside/outside the biological platforms. In this scenario, silicon-based compound matrices can offer different characteristics and advantages depending on their size configurations and PL emission mechanisms. On the other hand, a proper understanding of these multifaceted silicon nanomaterials' optical properties (emission mechanisms) can be exploited for pathogen detection and in situ applications in cells and tissues, embarking on a new era of bioimaging technology. [ABSTRACT FROM AUTHOR]

Terahertz (THz) waves, which fall between microwaves and infrared bands, possess intriguing electromagnetic properties of non-ionizing radiation, low photon energy, being highly sensitive to weak resonances, and non-polar material penetrability. Therefore, THz waves are extremely suitable for sensing and detecting chemical, pharmaceutical, and biological molecules. However, the relatively long wavelength of THz waves (30~3000 μm) compared to the size of analytes (1~100 nm for biomolecules, <10 μm for microorganisms) constrains the development of THz-based sensors. To circumvent this problem, metasurface technology, by engineering subwavelength periodic resonators, has gained a great deal of attention to enhance the resonance response of THz waves. Those metasurface-based THz sensors exhibit high sensitivity for label-free sensing, making them appealing for a variety of applications in security, medical applications, and detection. The performance of metasurface-based THz sensors is controlled by geometric structure and material parameters. The operating mechanism is divided into two main categories, passive and active. To have a profound understanding of these metasurface-assisted THz sensing technologies, we review and categorize those THz sensors, based on their operating mechanisms, including resonators for frequency shift sensing, nanogaps for enhanced field confinement, chirality for handedness detection, and active elements (such as graphene and MEMS) for advanced tunable sensing. This comprehensive review can serve as a guideline for future metasurfaces design to assist THz sensing and detection. [ABSTRACT FROM AUTHOR]

After the first visible photoluminescence (PL) from porous silicon (pSi), continuous efforts are made to fabricate Si‐based compound nanomaterials embedded in matrices such as oxide, nitride, and carbide to improve optical performance and industrial acceptability. These nanomaterials’ functional and desired properties (nanoparticles and quantum dots embedded in matrices) can vary significantly when embedded in technologically relevant matrices. However, exploring the exact emission mechanisms is one of the remaining challenges from the past few decades. To cover this gap, this review discusses the morphological and optoelectronic properties of Si‐based compound nanomaterials and their correlation with the quantum confinement effect and different surface states to find precise emission mechanisms. One of the biggest challenges of using silicon nanomaterials in the biological sector is the development of sensitive materials of low/acceptable toxicity for identifying target analytes either inside/outside the biological platforms. In this scenario, silicon‐based compound matrices can offer different characteristics and advantages depending on their size configurations and PL emission mechanisms. On the other hand, a proper understanding of these multifaceted silicon nanomaterials’ optical properties (emission mechanisms) can be exploited for pathogen detection and in situ applications in cells and tissues, embarking on a new era of bioimaging technology.

The first example of inkjet‐printed, electrolyte‐gated organic field‐effect transistors, fabricated on flexible polyimide substrates is presented. The interdigitated source and drain electrodes, and the coplanar gate electrodes, are inkjet‐printed using a homemade gold nanoparticle ink. A semiconducting ink based on the p‐type, organic semiconductor poly[2,5‐(2‐octyldodecyl)‐3,6‐diketopyrrolopyrrole‐alt‐5,5‐(2,5‐di(thien‐2‐yl)thieno [3,2‐b] thiophene)] (DPP‐DTT) is formulated and inkjet‐printed onto the channel. The performances of inkjet‐printed, coplanar devices are compared to those of transistors whose gate electrode consists in a metallic wire inserted in the electrolyte. Printed transistors show excellent electrical properties with field‐effect mobility as high as 0.04 cm2 V−1 s−1. The electrical behavior of inkjet‐printed, coplanar devices is also modeled using the Nernst–Planck–Poisson (NPP) equations, where the output and transfer curves are calculated based on the charge and potential distribution inside the device. Good quantitative agreement between the simulation and experiments is achieved, outlining the attainable use of NPP simulations as predictive tools for device design and optimization. To demonstrate an example of application, printed transistors are functionalized for the detection of complementary DNA strands. This study opens an avenue for the next generation of low‐cost, flexible sensors and circuits, both through experimental studies and device modeling. [ABSTRACT FROM AUTHOR]

Advances in nanotechnology and medical science have spurred the development of engineered nanomaterials and nanoparticles with particular focus on their applications in biomedicine. In particular, gold nanoparticles (AuNPs) have been the focus of great interest, due to their exquisite intrinsic properties, such as ease of synthesis and surface functionalization, tunable size and shape, lack of acute toxicity and favorable optical, electronic, and physicochemical features, which possess great value for application in biodetection and diagnostics purposes, including molecular sensing, photoimaging, and application under the form of portable and simple biosensors (e.g., lateral flow immunoassays that have been extensively exploited during the current COVID‐19 pandemic). We shall discuss the main properties of AuNPs, their synthesis and conjugation to biorecognition moieties, and the current trends in sensing and detection in biomedicine and diagnostics. This article is categorized under:Diagnostic Tools > BiosensingDiagnostic Tools > In Vitro Nanoparticle‐Based SensingDiagnostic Tools > In Vivo Nanodiagnostics and Imaging [ABSTRACT FROM AUTHOR]

[Display omitted] • Present the first example of ultrasmall photothermal nanoprobe, VO x nanoparticle, for enzyme-based biodetection. • The ultrasmall nanoprobe has higher reactivity and allows faster biodetection than the large-size nanoprobes. • Our photothermal methods only use one enzyme for biorecognition and low-cost device for read out. Low-cost photothermal probes facilitate the practical application of photothermal detection. However, current photothermal nanoprobes are generally larger in size and thus have slower reactivity with analytes, which is not conducive to rapid testing. Therefore, ultra-small photothermal nanoprobes would be preferred but have not been reported. Here, the ultrasmall VO x nanoparticle is constructed as low-cost photothermal nanoprobe, which is more reactive to H 2 O 2 and thus has reduced response time. In cooperation with enzymes, this nanoprobe can be used for photothermal detection of other biomolecules, such as glucose and uric acid. Compare with the standard colorimetric method, the photothermal method with ultrasmall VO x nanoparticle has high similarity and low analytical error of less than 5 %, which is sufficient for actual practice. [ABSTRACT FROM AUTHOR]

An optimized, well-tested and validated targeted genomic sequencing-based high-throughput assay is currently not available ready for routine biodefense and biosurveillance applications. Earlier, we addressed this gap by developing and establishing baseline comparisons of a multiplex end-point Polymerase Chain Reaction (PCR) assay followed by Oxford Nanopore Technology (ONT) based amplicon sequencing to real time PCR and customized data processing. Here, we expand upon this effort by identifying the optimal ONT library preparation method for integration into a novel software platform ONT-DART (ONT-Detection of Amplicons in Real-Time). ONT-DART is a dockerized, real-time, amplicon-sequence analysis workflow that is used to reproducibly process and filter read data to support actionable amplicon detection calls based on alignment metrics, within sample statistics, and no-template control data. This analysis pipeline was used to compare four ONT library preparation protocols using R9 and Flongle (FL) flow cells. The two 4-Primer methods tested required the shortest preparation times (5.5 and 6.5 h) for 48 libraries but provided lower fidelity data. The Native Barcoding and Ligation methods required longer preparation times of 8 and 12 h, respectively, and resulted in higher overall data quality. On average, data derived from R9 flow cells produced true positive calls for target organisms more than twice as fast as the lower throughput FL flow cells. These results suggest that utilizing the R9 flowcell with an ONT Native Barcoding amplicon library method in combination with ONT-DART platform analytics provides the best sequencing-based alternative to current PCR-based biodetection methods. [ABSTRACT FROM AUTHOR]

Abstract Metal graphitic nanocapsules have the advantages of both graphitic and metal nanomaterials, showing great promise in biomedicine. On one hand, the chemically inert graphitic shells are able to protect the metal core from external environments, quench the fluorescence signal from the biological system, offer robust platform for targeted molecules or drugs loading, and act as stable Raman labels or internal standard molecule. On the other hand, the metal cores with different compositions, sizes, and morphologies show unique physicochemical properties, and further broaden their biomedical functions. In this review, we firstly introduce the preparation, classification, and properties of metal graphitic nanocapsules, then summarize the recent progress of their applications in biodetection, bioimaging, and therapy. Challenges and their development prospects in biomedicine are eventually discussed in detail. We expect the versatile metal graphitic nanocapsules will advance the development of future clinical biomedicine.

Plasmonic nanoassemblies are well-defined organizing of elementary metallic nanocrystal building blocks into ordered architectures across multiple scales, which constituents an exciting route to engineer nanomaterials structures with novel properties. Such nanoassemblies can accurately enhance, guide, and switch electromagnetic field at the nanoscale, which is shaping new-generation technologies with a plethora of applications, such as ultrasensitive bimolecular sensors, cancer diagnostics, and photothermal therapy (PTT), to name a few. In this review, we mainly focus on the plasmonic nanoassemblies, including the structure design, property control, and biomedical applications. The guiding principles have been first clarified with design rules being suggested. Then, the methodologies for fabrication of surface-enhanced Raman scattering-based (SERS-based) biodetection devices have been discussed. Finally, we summarized the PTT by using the plasmonic nanoassemblies as bioprobes for theranostics. Based on the facile yet efficient fabrication methods, high-efficient optoelectronic properties, and high performance in biomedical applications, we firmly believe that the plasmonic nanoassemblies can be integrated with portable devices for next-generation biosensors and biomedical theranostics.

Microorganisms are omnipresent and inseparable from our life. Many of them are beneficial to humans, while some are not. Importantly, foods and beverages are susceptible to microbial contamination, with their toxins causing illnesses and even death in some cases. Therefore, monitoring and detecting harmful microorganisms are critical to ensuring human health and safety. For several decades, many methods have been developed to detect and monitor microorganisms and their toxicants. Conventionally, nucleic acid analysis and antibody-based analysis were used to detect pathogens. Additionally, diverse chromatographic methods were employed to detect toxins based on their chemical and structural properties. However, conventional techniques have several disadvantages concerning analysis time, sensitivity, and expense. With the advances in biotechnology, new approaches to detect pathogens and toxins have been reported to compensate for the disadvantages of conventional analysis from different research fields, including electrochemistry, nanotechnology, and molecular biology. Among them, we focused on the recent studies of transcription factor (TF)-based biosensors to detect microorganisms and discuss their perspectives and applications. Additionally, the other biosensors for detecting microorganisms reported in recent studies were also introduced in this review. [ABSTRACT FROM AUTHOR]

Terahertz (THz) waves, which fall between microwaves and infrared bands, possess intriguing electromagnetic properties of non-ionizing radiation, low photon energy, being highly sensitive to weak resonances, and non-polar material penetrability. Therefore, THz waves are extremely suitable for sensing and detecting chemical, pharmaceutical, and biological molecules. However, the relatively long wavelength of THz waves (30~3000 μm) compared to the size of analytes (1~100 nm for biomolecules,

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]

Abstract 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 Background The state-of-the-art in nucleic acid based biodetection continues to be polymerase chain reaction (PCR), and many real-time PCR assays targeting biodefense pathogens for biosurveillance are in widespread use. These assays are predominantly singleplex; i.e. one assay tests for the presence of one target, found in a single organism, one sample at a time. Due to the intrinsic limitations of such tests, there exists a critical need for high-throughput multiplex assays to reduce the time and cost incurred when screening multiple targets, in multiple pathogens, and in multiple samples. Such assays allow users to make an actionable call while maximizing the utility of the small volumes of test samples. Unfortunately, current multiplex real-time PCR assays are limited in the number of targets that can be probed simultaneously due to the availability of fluorescence channels in real-time PCR instruments. Results To address this gap, we developed a pipeline in which the amplicons produced by a 14-plex end-point PCR assay using spiked samples were subsequently sequenced using Nanopore technology. We used bar codes to sequence multiple samples simultaneously, leading to the generation and subsequent analysis of sequence data resulting from a short sequencing run time (

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]

The exploration of performance luminescence near-infrared (NIR) material is crucial for rapidly developing NIR spectroscopic techniques. Herein, the NIR LaMg 0.5 Sn 0.5 O 3 :Cr3+ phosphor was synthesized by a high temperature solid-state method. And its luminescence performance were improved by [In3+-Sc3+] substituting for [Mg2+-Sn4+]. The half-peak width can be expanded to 211 nm, the emission intensity can reach the seven times of that un-substitution, and the emission intensity at 423 K was maintained at 60 % of that at room temperature, moreover, the internal quantum efficiency can reach 54.2 %. On this basis, the phosphor converted light emitting diodes (pc -LEDs) were achieved by combining La(Mg 1-x Sn 1-x In x Sc x) 0.5 O 3 :Cr3+ with blue LED, importantly, it can be applied to the biodetection and night vision lighting, which indicate its application value. • The emission of La(Mg 0.5 Sn 0.5 In 0.5 Sc 0.5) 0.5 O 3 : 0.003Cr3+ can red-shift to 821 nm by [In3+-Sc3+] co-substitute for [Mg2+-Sn4+]. • The half-peak width can expand to 211 nm. • The emission intensity can be enhanced seven times of that before substitution. • The phosphor maintains an internal quantum efficiency of 54.2 %. [ABSTRACT FROM AUTHOR]

Microorganisms are omnipresent and inseparable from our life. Many of them are beneficial to humans, while some are not. Importantly, foods and beverages are susceptible to microbial contamination, with their toxins causing illnesses and even death in some cases. Therefore, monitoring and detecting harmful microorganisms are critical to ensuring human health and safety. For several decades, many methods have been developed to detect and monitor microorganisms and their toxicants. Conventionally, nucleic acid analysis and antibody-based analysis were used to detect pathogens. Additionally, diverse chromatographic methods were employed to detect toxins based on their chemical and structural properties. However, conventional techniques have several disadvantages concerning analysis time, sensitivity, and expense. With the advances in biotechnology, new approaches to detect pathogens and toxins have been reported to compensate for the disadvantages of conventional analysis from different research fields, including electrochemistry, nanotechnology, and molecular biology. Among them, we focused on the recent studies of transcription factor (TF)-based biosensors to detect microorganisms and discuss their perspectives and applications. Additionally, the other biosensors for detecting microorganisms reported in recent studies were also introduced in this review.

Lanthanide-doped nanoparticles possess numerous advantages including tunable luminescence emission, narrow peak width and excellent optical and thermal stability, especially concerning the long lifetime from microseconds to milliseconds. Differing from other shorter-lifetime fluorescent nanomaterials, the long lifetime of lanthanide-doped nanomaterials is independent with background fluorescence interference and biological tissue depth. This review presents the recent advances in approaches to regulating the lifetime and applications of bioimaging and biodetection. We begin with the introduction of the strategies for regulating the lifetime by modulating the core–shell structure, adjusting the concentration of sensitizer and emitter, changing energy transfer channel, establishing a fluorescence resonance energy transfer pathway and changing temperature. We then summarize the applications of these nanoparticles in biosensing, including ion and molecule detecting, DNA and protease detection, cell labeling, organ imaging and thermal and pH sensing. Finally, the prospects and challenges of the lanthanide lifetime regulation for fundamental research and practical applications are also discussed.

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]

Nanotechnology offers the possibility of operating on the same scale length at which biological processes occur, allowing to interfere, manipulate or study cellular events in disease or healthy conditions. The development of hybrid nanostructured materials with a high degree of chemical control and complex engineered surface including biological targeting moieties, allows to specifically bind to a single type of molecule for specific detection, signaling or inactivation processes. Magnetite nanostructures with designed composition and properties are the ones that gather most of the designs as theragnostic agents for their versatility, biocompatibility, facile production and good magnetic performance for remote in vitro and in vivo for biomedical applications. Their superparamagnetic behavior below a critical size of 30 nm has allowed the development of magnetic resonance imaging contrast agents or magnetic hyperthermia nanoprobes approved for clinical uses, establishing an inflection point in the field of magnetite based theragnostic agents. [ABSTRACT FROM AUTHOR]

Background: The state-of-the-art in nucleic acid based biodetection continues to be polymerase chain reaction (PCR), and many real-time PCR assays targeting biodefense pathogens for biosurveillance are in widespread use. These assays are predominantly singleplex; i.e. one assay tests for the presence of one target, found in a single organism, one sample at a time. Due to the intrinsic limitations of such tests, there exists a critical need for high-throughput multiplex assays to reduce the time and cost incurred when screening multiple targets, in multiple pathogens, and in multiple samples. Such assays allow users to make an actionable call while maximizing the utility of the small volumes of test samples. Unfortunately, current multiplex real-time PCR assays are limited in the number of targets that can be probed simultaneously due to the availability of fluorescence channels in real-time PCR instruments. Results: To address this gap, we developed a pipeline in which the amplicons produced by a 14-plex end-point PCR assay using spiked samples were subsequently sequenced using Nanopore technology. We used bar codes to sequence multiple samples simultaneously, leading to the generation and subsequent analysis of sequence data resulting from a short sequencing run time (< 10 min). We compared the limits of detection (LoD) of real-time PCR assays to Oxford Nanopore Technologies (ONT)-based amplicon sequencing and estimated the sample-to-answer time needed for this approach. Overall, LoDs determined from the first 10 min of sequencing data were at least one to two orders of magnitude lower than real-time PCR. Given enough time, the amplicon sequencing approach is approximately 100 times more sensitive than real-time PCR, with detection of amplicon specific reads even at the lowest tested spiking concentration (around 2.5–50 Colony Forming Units (CFU)/ml). Conclusions: Based on these results, we propose amplicon sequencing assay as a viable alternative to replace the current real-time PCR based singleplex assays for higher throughput biodefense applications. We note, however, that targeted amplicon specific reads were not detectable even at the highest tested spike concentrations (2.5 X 104–5.0 X105 CFU/ml) without an initial amplification step, indicating that PCR is still necessary when utilizing this protocol. [ABSTRACT FROM AUTHOR]

Oral cancer belongs to the group of head and neck cancers, and, despite its large diffusion, it suffers from low consideration in terms of prevention and early diagnosis. The main objective of the SMILE platform is the development of a low-cost device for oral cancer early screening with features of high sensitivity, specificity, and ease of use, with the aim of reaching a large audience of possible users and realizing real prevention of the disease. To achieve this goal, we realized two microfluidic devices exploiting low-cost materials and processes. They can be used in combination or alone to obtain on-chip sample preparation and/or detection of circulating tumor cells, selected as biomarkers of oral cancer. The realized devices are completely transparent with plug-and-play features, obtained thanks to a highly customized architecture which enables users to easily use them, with potential for a common use among physicians or dentists with minimal training.

Photonic crystal (PC) materials exhibit unique structural colors that originate from their intrinsic photonic band gap. Because of their highly ordered structure and distinct optical characteristics, PC-based biomaterials have advantages in the multiplex detection, biomolecular screening and real-time monitoring of biomolecules. In addition, PCs provide good platforms for drug loading and biomolecule modification, which could be applied to biosensors and biological carriers. A number of methods are now available to fabricate PC materials with variable structure colors, which could be applied in biomedicine. Emphasis is given to the description of various applications of PC materials in biomedicine, including drug delivery, biodetection and tumor screening. We believe that this article will promote greater communication among researchers in the fields of chemistry, material science, biology, medicine and pharmacy.

In this work, we design new plasmonic paper-based nanoplatforms with interesting capabilities in terms of sensitivity, efficiency, and reproducibility for promoting multimodal biodetection via Localized Surface Plasmon Resonance (LSPR), Surface Enhanced Raman Spectroscopy (SERS), and Metal Enhanced Fluorescence (MEF). To succeed, we exploit the unique optical properties of gold nanobipyramids (AuBPs) deposited onto the cellulose fibers via plasmonic calligraphy using a commercial pen. The first step of the biosensing protocol was to precisely graft the previously chemically-formed p-aminothiophenol@Biotin system, as active recognition element for target streptavidin detection, onto the plasmonic nanoplatform. The specific capture of the target protein was successfully demonstrated using three complementary sensing techniques. As a result, while the LSPR based sensing capabilities of the nanoplatform were proved by successive 13–18 nm red shifts of the longitudinal LSPR associated with the change of the surface RI after each step. By employing the ultrasensitive SERS technique, we were able to indirectly confirm the molecular identification of the biotin-streptavidin interaction due to the protein fingerprint bands assigned to amide I, amide III, and Trp vibrations. Additionally, the formed biotin-streptavidin complex acted as a spacer to ensure an optimal distance between the AuBP surface and the Alexa 680 fluorophore for achieving a 2-fold fluorescence emission enhancement of streptavidin@Alexa 680 on the biotinylated nanoplatform compared to the same complex on bare paper (near the plasmonic lines), implementing thus a novel MEF sensing nanoplatform. Finally, by integrating multiple LSPR, SERS, and MEF nanosensors with multiplex capability into a single flexible and portable plasmonic nanoplatform, we could overcome important limits in the field of portable point-of-care diagnostics.

The coronavirus disease 2019 (COVID-19) pandemic has highlighted bottlenecks in large-scale, frequent testing of populations for infections. Polymerase chain reaction (PCR)-based diagnostic tests are expensive, reliant on centralized labs, can take days to deliver results, and are prone to backlogs and supply shortages. Antigen tests that bind and detect the surface proteins of a virus are rapid and scalable but suffer from high false negative rates. To address this problem, an inexpensive, simple, and robust 60-minute do-it-yourself (DIY) workflow to detect viral RNA from nasal swabs or saliva with high sensitivity (0.1 to 2 viral particles/μL) and specificity (>97% true negative rate) utilizing reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed. ALERT (Accessible LAMP-Enabled Rapid Test) incorporates the following features: (1) increased shelf-life and ambient temperature storage, compared to liquid reaction mixes, by using wax layers to isolate enzymes from other reagents; (2) improved specificity compared to other LAMP end-point reporting methods, by using sequence-specific QUASR (quenching of unincorporated amplification signal reporters); (3) increased sensitivity, compared to methods without purification through use of a magnetic wand to enable pipette-free concentration of sample RNA and cell debris removal; (4) quality control with a nasopharyngeal-specific mRNA target; and (5) co-detection of other respiratory viruses, such as influenza B, by multiplexing QUASR-modified RT-LAMP primer sets. The flexible nature of the ALERT workflow allows easy, at-home and point-of-care testing for individuals and higher-throughput processing for labs and hospitals. With minimal effort, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific primer sets can be swapped out for other targets to repurpose ALERT to detect other viruses, microorganisms, or nucleic acid-based markers.

Quantum dots (QD) are being evaluated as inorganic nanoparticles for both in vitro and in vivo optical imaging. They are also used as sensors or vehicles for targeted drug delivery combined with optical imaging. In this study, we demonstrated that glutathione‐coated Ag2S QDs (GSH‐Ag2S QDs) act as a substrate analogue of glutathione S‐transferase (GST) enzymes for the first time in the literature. The GSTs belong to a major group of detoxification enzymes involved in the detoxification metabolism responsible for the protection of cells against reactive oxygen species (ROS) or electrophiles. GST isozymes are impaired in the various diseases such as neurological diseases and cancer. We evaluated the interaction of GST‐pi enzyme with GSH‐Ag2S QDs, which have never been studied in the literature before, using both fluorometric and spectrophotometric methods. Our data showed that GSH‐Ag2S QDs gave reaction with GST enzyme as a substrate analogue. In conclusion, our data may help to guide researchers for further development of sensing systems for GST activity which is impaired in various diseases including cancer. [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]

Highlights • We showed a new optical solution to quantify nanoparticle/membrane interactions. • We turned sum frequency generation (SFG) in a label-free and highly sensitive method to quantify nano-bio-interactions. • We used the vibrational nonlinear optical response of interfacial water as signal of nanoparticle/membrane interactions. • We demonstrated the high sensitivity of the nonlinear optical detection of water to very low nanoparticle concentrations. • We obtained fast biodetection responses. Abstract In this work, we demonstrated for the first time that the nonlinear optical (NLO) response of interfacial water, as obtained from sum frequency generation (SFG) spectroscopy, can be used as a quantitative, sensitive and label-free probe for nanoparticle/membrane interactions. We probed water molecules that are organized close to the surface of solid-supported model membranes, which mimic the cell barrier and act as sensing platforms, and we measured the SFG response of OH stretching modes of the above interfacial water upon interaction with 5-nm positive gold nanoparticles (AuNPs) in real time. We analyzed three parameters, representing the SFG response of interfacial water: the signal gain, the detection time and the interaction time. A clear dependence on the concentration of AuNPs interacting with the sensing platforms was observed, providing quantitative data about these interactions. From this information, we evaluated the detection performance of this nonlinear optical tool with two sensing platforms, namely, solid-supported bilayers of DPPC (1,2-dipalmitoyl- sn -glycero-3-phosphocholine) or of DOPC (1,2-dioleoyl- sn -glycero-3-phosphocholine). With the DPPC sensing platform, the SFG response of water allowed for the detection of Au concentrations as low as 50 ng/mL. This sensitivity was achieved in less than 300 s. With the DOPC sensing platform, the sensitivity was even better, with a detection threshold of 0.8 ng/mL of gold. However, the required detection rate was approximately 4000 s. Quantifying biological interactions through the NLO response of interfacial water could be extended to many biological host-guest interactions; thus, SFG spectroscopy is a promising quantitative, sensitive and label-free biodetection system. [ABSTRACT FROM AUTHOR]

• Design strategies of scale-up DNA nanostructures are outlined. • Building principles of nanoobjects based on DNA nanotechnology are discussed. • Current applications exploiting the structural features are reviewed. Nanofabrication refers to manufacturing objects with nanometer dimensions. The evolution of DNA nanotechnology has brought new inspirations to this field, owing to the unprecedented programmability of DNA molecules. By combining with other components, DNA nanostructures can template the growth of heterogeneous materials, support delicate plasmonic devices, build smart drug delivery vehicles and detect biomolecular targets. This article focuses on key strategies for DNA-based nanofabrication and highlights recent developments in chemical reactions confined on DNA nanostructures, including metallization, mineralization and polymer coating. We also review applications based on DNA nanofabrication and propose perspective in this field. [ABSTRACT FROM AUTHOR]

Self-assembled three-dimensional (3-D) colloidal crystals have been extensively utilized in nanolithography for fabricating a wide spectrum of functional periodic nanostructures for important technological applications. Here a simple and versatile way is reported using silica colloids to prepare close-packed particle multilayers by the Langmuir– Blodgett technique to create highly ordered 3-D colloidal crystals with unusual nanoarrays on a large variety of substrates. Successive deposition of monolayers using amphiphilic molecules in this approach allows control of the layer thickness, particle size, and especially packing structure of them in each layer. It has been demonstrated that the Langmuir–Blodgett film’s transparency and high antiglare optical properties are preserved even after multiple colloidal particle transfers on both straight and curved surfaces. The surface prepared by the Langmuir–Blodgett technique shows remarkable sensitivity for potential biodetection applications. These colloidal templated films have an optical response time of less than 40 s against essential bioproduct vapors. It is shown that the results are consistent with the Kelvin equation (ln P/Po = –2 Vl γ/rRT) when the liquid water layer is getting thicker. [ABSTRACT FROM AUTHOR]

Abstract With the tangible threat posed by the release of chemical and biological warfare (CBW) agents, detection of airborne pathogens is a critical military and security concern. Recent air sampling techniques developed for biocollection take advantage of Electrowetting on Dielectric (EWOD) to recover material, producing highly concentrated droplet samples. Bespoke EWOD-based digital microfluidics platforms are very well suited to take full advantage of the microlitre concentrated droplet resulting from this recovery process. In this paper we present a free-standing, fully automated DMF platform for immunoassay. Using this system, we demonstrate the automated detection of four classes of CBW agent simulant biomolecules and organisms each representing credible threat agents. Taking advantage of the full magnetic separation process with antibody-bound microbeads, rapid and complete separation of specific target antigen can be achieved with minimal washing steps allowing for very rapid detection. Here, we report clear detection of four categories of antigens achieved with assay completion times of between six and ten minutes. Detection of HSA, Bacillus atrophaeus (BG spores), MS2 bacteriophage and Escherichia coli are demonstrated with estimated limit of detection of respectively 30 ng ml-1, 4 × 104 cfu ml-1, 106 pfu ml-1 and 2 × 107 cfu ml-1. The fully-integrated portable platform described in this paper is highly compatible with the next generation of electrowetting-coupled air samplers and thus shows strong potential toward future in-field deployable biodetection systems and could have key implication in life-changing sectors such as healthcare, environment or food security. Highlights • Digital microfluidics (DMF) devices are seen as promising candidates to address the detection of aerosolised pathogens. • A free-standing, automated DMF platform for immunoassay was developed for direct detection of biomolecules and organisms. • For the first time using a DMF system, rapid detection of four classes of CBW agent simulants was demonstrated. • Rapid detection has been achieved with assay times between six minutes and ten minutes. Bullet point. • Fully automated detection of E. Coli, BG, MS2 and HSA has been demonstrated as a proof of concept for versatile biodetection. [ABSTRACT FROM AUTHOR]

Highlights • The fundamental photophysics of Eu3+-activated luminescent nanoprobes are overviewed. • The strategies for enhancing the downshifting/upconverting luminescence of Eu3+-activated nanoprobes are summarized. • Heterogeneous and homogeneous biodetections based on Eu3+-activated luminescent nanoprobes are exemplified. • In vitro and in vivo bioimagings based on Eu3+-activated luminescent nanoprobes are specifically outlined. Abstract Trivalent europium ions (Eu3+) activated inorganic materials, known as one of the most important red-emitting phosphors, are emerging as an attractive class of luminescent materials over the past decades. Specifically, Eu3+ ion is considered as an ideal spectroscopic probe to decipher the local environment in view of its non-degenerate ground state of 7F 0 and excitation state of 5D 0. Benefiting from the intense long-lived luminescence from 5D 0 , Eu3+-activated inorganic nanoparticles are also frequently reported as luminescent probes in biological assays and medical imaging. With the development of advanced synthesis strategies and characterization techniques, more new understanding or progress in Eu3+-activated luminescent nanoprobes have been gained with regard to their fundamental photophysics/photochemistry properties and versatile bioapplications. As such, it is urgent to renew the knowledge in this field. Rather than being exhaustive, this review aims to highlight the latest progress in the electronic structures, optical properties and emerging bioapplications of Eu3+-activated nanoprobes, which covers from spectroscopic site symmetry, excited-state dynamics, downshifting/upconversion luminescence enhancement strategies, and luminescent biosensing, with an emphasis on their heterogeneous/homogeneous biodetection as well as in vitro and in vivo bioimaging. Some future prospects and efforts toward this rapidly developing field are also discussed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The test system is able to selectively adsorb inhibitors for acetylcholinesterase. • Unspecific adsorptions were avoided with the optimized operational conditions. • The immobilized enzyme resulted around 200-fold more stable than soluble enzyme. • The system was reused 15 times with negligible loss of activity. • It permits the easy characterization of potential drugs in Alzheimer´s disease. Abstract This study presents a rapid and simple method to screen and detect new drugs to treat Alzheimer's disease. The method uses a test system based on an immobilized acetylcholinesterase from Electrophorus electricus (AChE). The optimal AChE immobilized preparation retained 65% of the original catalytic activity; immobilization improved AChE stability by approximately 200-fold. Inhibition and usability of immobilized AChE in real conditions was studied using tacrine as model inhibitor. The immobilized system enabled to determine variables like IC 50 , K i , K D , and ΔGº´ in an uncomplicated way and proved to be an interesting tool for rapid screening of the ability of new target compounds to inhibit AChE. System inertia was also studied to avoid false positives. The system was optimized by making the un-specific interactions between AChE and other compounds from a vegetable extract negligible. Optimization of the immobilized AChE system allowed its efficient application to test mixtures of tacrine, a standard inhibitor, and vegetable extracts as AChE inhibitors. The system was reused at least 15 times with minimal AChE activity loss. [ABSTRACT FROM AUTHOR]

Micro/nanomotors (MNMs) emerge as a vital candidate for biosensing due to its nano-size structure, high surface-to-area ratio, directional mobility, biocompatibility, and ease of functionalization, therefore being able to detect objects with high efficiency, precision, and selectivity. The driving mode, nanostructure, materials property, preparation technique, and biosensing applications have been thoroughly discussed in publications. To promote the MNMs-based biosensors from in vitro to in vivo, it is necessary to give a comprehensive discussion from the perspective of sensing performances enhancement. However, until now, there is few reviews dedicated to the systematic discussion on the multiple performance enhancement schemes and the current challenges of MNMs-based biosensors. Bearing it in mind and based on our research experience in this field, we summarized the enhancement methods for biosensing properties such as sensitivity, selectivity, detection time, biocompatibility, simplify system operation, and environmental availability. We hope that this review provides the readers with fundamental understanding on performance enhancement schemes for MNMs-based biosensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The design and challenges of frequency upconversion luminescence dyes are discussed. Frequency upconversion luminescence (FUCL) is a specific anti-Stokes process whereby excitation of long wavelengths with low energy can be converted to emission of short wavelengths with high energy, which has attracted increasing attention in biological applications due to its superior features, such as low autofluorescence and excellent signal-to-noise ratios. In this review, we introduce the differences between traditional fluorescence and FUCL, summarize the composition, molecular design and characteristics of FUCL materials and conduct a survey of recent advances in FUCL systems, focusing on their broad applications in the fields of bioimaging, biodetection and cancer therapy. In addition, we further present the current challenges and perspectives with the expectation of making new breakthroughs in FUCL materials in the near future. [ABSTRACT FROM AUTHOR]

Nanotechnology offers the possibility of operating on the same scale length at which biological processes occur, allowing to interfere, manipulate or study cellular events in disease or healthy conditions. The development of hybrid nanostructured materials with a high degree of chemical control and complex engineered surface including biological targeting moieties, allows to specifically bind to a single type of molecule for specific detection, signaling or inactivation processes. Magnetite nanostructures with designed composition and properties are the ones that gather most of the designs as theragnostic agents for their versatility, biocompatibility, facile production and good magnetic performance for remote in vitro and in vivo for biomedical applications. Their superparamagnetic behavior below a critical size of 30 nm has allowed the development of magnetic resonance imaging contrast agents or magnetic hyperthermia nanoprobes approved for clinical uses, establishing an inflection point in the field of magnetite based theragnostic agents.

Abstract Significant progress on upconversion‐nanoparticle (UCNP)‐based probes is witnessed in recent years. Compared with traditional fluorescent probes (e.g., organic dyes, metal complexes, or inorganic quantum dots), UCNPs have many advantages such as non‐autofluorescence, high chemical stability, large light‐penetration depth, long lifetime, and less damage to samples. This article focuses on recent achievements in the usage of lanthanide‐doped UCNPs as efficient probes for biodetection since 2014. The mechanisms of upconversion as well as the luminescence resonance energy transfer process is introduced first, followed by a detailed summary on the recent researches of UCNP‐based biodetections including the detection of inorganic ions, gas molecules, reactive oxygen species, and thiols and hydrogen sulfide.

Recent development of Surface-Enhanced Raman Spectroscopy (SERS) as an extremely sensitive analytical method requires the introduction of flexible SERS substrate for express, out- doors measurements. Herein, we demonstrate an approach for creation of flexible SERS substrate, exhibiting high reproducibility and reliability of analytical results. The flexible SERS substrates are produced by the excimer laser patterning of thin polymer films, followed by the deposition of thin Au layer. The thickness of polymer films allows their further self-adhesion to a targeted surface. The proposed method allows the creation of macroscopically large plasmon-active area on the polymer film. The effectivity of SERS substrate was optimized by proper choice of the parameters of laser pattering, the thickness of flexible polymer film and amount of the deposited gold. The substrates were optimized using the typical SERS analyte - R6G. Suitability of the present substrate for the detection of bio-objects (yeast cell) was demonstrated too. All SERS measurements were performed with portable Raman spectrometers and the possibility of the implementation of created SERS substrate for rapid and unpretentious outdoor analysis was demonstrated. [ABSTRACT FROM AUTHOR]

Introduction: An update on the uses and applications of the non-cross-linking (NCL) hybridization assay based on the spectral modulation of gold nanoparticles (AuNPs) are presented, emphasizing DNA and RNA detection. Areas covered: Nanotechnology is strongly impacting the way we address diagnostics and therapeutics. In fact, nanoscale devices and particles have been used in a variety of platforms for improved biosensing and, more interestingly, for molecular diagnostics. AuNPs have been used in a great diversity of DNA and RNA detection strategies that are based on their nanoscale properties. Their unique optical properties have put them at the forefront of colorimetric sensing platforms. Among these, those relying on the NCL mechanism using DNA-modified AuNPs have shown remarkable versatility and simplicity for molecular detection of human pathogens, identification of single base alterations at the basis of human disease, gene expression, among others. Application of the NCL assay to molecular diagnostics will be discussed considering the challenges for validation and clinically relevant targets. Expert commentary: Integration of the NCL approach using AuNPs into chip biosensing platforms, projecting miniaturization and portability, will be addressed in terms of the future, i.e. clinical validation and translation to market. [ABSTRACT FROM AUTHOR]

In the broad research of the GMR bio-sensing technology, it is vital to explore appropriate magnetic labels and its influences on the detection signal. In this work, four kinds of ferrite particles of γ-Fe 2 O 3 , CoFe 2 O 4 , NiFe 2 O 4 and NiZnFe 2 O 4 were prepared through calcining the Dimethyl Formamide (DMF) solution of the transition metal nitrates [Fe(NO 3 ) 3 and X(NO 3 ) 2 , X = Co, Ni, Zn] to study the effect of magnetic properties on detection signals using a DC in-plane measuring method. It was revealed that for four particles, the output voltage differences | ΔV | between with and without magnetic particles exhibit log-linear functions of the particles concentrations x in the range from 0.1 to 10 ng/mL. A very low limitation of detection (LOD) of 0.1 ng/mL for all the samples was obtained, which is two orders smaller than that in the previous work. Moreover, the change of output voltage difference at the LOD (| ΔV lim |) is proportional to the magnetization at bias field (bias magnetization, M bias ), which indicates that larger M bias leads to a lower LOD. This work provides a useful guidance in selecting or preparing magnetic labels to enhance the sensitivity of GMR biosensors. [ABSTRACT FROM AUTHOR]

Lateral Flow Immunoassay (LFIA) strips are among the most widely-used and cost-effective biodetection tools that have applications in disease diagnosis and food safety monitoring. In this paper, we demonstrate the novel application of Thermophotonic Lock-In Imaging (TPLI) in quantitative and sensitive interpretation of LFIA strip results used to detect the pregnancy hormone human chorionic gonadotropin ( hCG ) as a proof-of-concept analyte. Existing optical immunoassay readers, based on image acquisition and processing algorithms, rely on reflective signals (color intensity) emanating from the surface of the LFIA. Such contrast mechanism results in missing a large amount of signal from gold nanoparticles (GNP) trapped inside the bulk of the LFIA nitrocellulose strips and leads to suboptimal detection thresholds and sensitivities. TPLI, on the other hand, operates based on diffusion of thermal waves and as such does not require optical transparency to reach GNPs in the bulk of the strip. Our experimental results indicate that the developed TPLI system is able to detect GNP- hCG conjugates at concentrations as low as 0.2  mIU , while the detection threshold of human visual inspection and commercial optical immunoassay readers were both found to be 2  mIU . Miniaturization of TPLI technique will enable a highly sensitive, quantitative, low-cost, and truly point-of-care total analysis test interpretation system for LFIAs, facilitating critical early stage detection of diseases or biochemical conditions. [ABSTRACT FROM AUTHOR]