Sensors & diagnostics最新文献

In large-scale radiation exposure events, the ability to triage potential victims by the received radiation dosage is crucial. This can be evaluated by radiation-induced biological changes. Radiation-responsive mRNA is a class of biomarkers that has been explored for dose-dependency with methods such as RT-qPCR. However, these methods are challenging to implement for point-of-care devices. We have designed and used molecular beacons as probes for the measurement of radiation-induced changes of intracellular mRNA in a microfluidic device towards determining radiation dosage. Our experiments, in which fixed TK6 cells labeled with a molecular beacon specific to BAX mRNA exhibited dose-dependent fluorescence in a manner consistent with RT-qPCR analysis, demonstrate that such intracellular molecular probes can potentially be used in point-of-care radiation biodosimetry. This proof of concept could readily be extended to any RNA-based test to provide direct measurements at the bedside.

Fast and reliable identification of pathogenic bacteria is of upmost importance to human health and safety. Methods that are currently used in clinical practice are often time consuming, require expensive equipment, trained personnel, and therefore have limited applications in low resource environments. Molecular identification methods address some of these shortcomings. At the same time, they often use antibodies, their fragments, or other biomolecules as recognition units, which makes such tests specific to a particular target. In contrast, array-based methods use a combination of reporters that are not specific to a single pathogen. These methods provide a more data-rich and universal response that can be used for identification of a variety of bacteria of interest. In this report, we demonstrate the application of the excitation–emission spectroscopy of an environmentally sensitive fluorescent dye for identification of pathogenic bacterial species. 2-(4′-Dimethylamino)-3-hydroxyflavone (DMAF) interacts with the bacterial cell envelope resulting in a distinct spectral response that is unique to each bacterial species. The dynamics of dye–bacteria interaction were thoroughly investigated, and the limits of detection and identification were determined. Neural network classification algorithm was used for pattern recognition analysis and classification of spectral data. The sensor successfully discriminated between eight representative pathogenic bacteria, achieving a classification accuracy of 85.8% at the species level and 98.3% at the Gram status level. The proposed method based on excitation–emission spectroscopy of an environmentally sensitive fluorescent dye is a powerful and versatile diagnostic tool with high accuracy in identification of bacterial pathogens.

The contamination of per- and polyfluoroalkyl substances (PFAS) in drinking water presents a significant concern and requires a simple, portable detection method. This study aims to demonstrate the effectiveness of Raman and surface-enhanced Raman scattering (SERS) spectroscopies for identifying and quantifying various PFASs in water. Experimental Raman spectra of different PFASs reveal unique characteristic peaks that enable their classification. While direct SERS measurements from silver nanorod (AgNR) substrates may not exhibit distinct PFAS characteristic peaks, the presence of PFAS on SERS substrates induces noticeable spectral changes. By integration with machine learning (ML) techniques, these SERS spectra can be used to successfully differentiate and quantify PFOA in water, achieving a limit of detection (LOD) of 1 ppt. Modifying the AgNR substrates with cysteine and 6-mercapto-1-hexanol enhances the differentiation and quantification capabilities of SERS-ML. Despite alkanethiol molecules affecting spectral features, PFAS and PFOS concentrations produce observable spectral variations. A support vector machine model achieves 93% accuracy in differentiating PFOA, PFOS, and references, independent of concentration. A support vector regression model further establishes LODs of 1 ppt for PFOA and 4.28 ppt for PFOS. By removing spectra with concentrations lower than LODs, the classification accuracy is improved to 95%.

Among the various organophosphorus-based chemical warfare agents, nerve agents pose severe threats to national defense and public safety. Among them, sarin gas is a severe one that has been employed in various terrorist activities recently. The development of chromo-fluorogenic probes for their detection is still in its infancy. Aiming in this direction, the present article introduces a highly selective and specific chromo-fluorogenic probe, (E)-3-(((4-(benzo[d]oxazol-2-yl)phenyl)imino)methyl)-2-methoxy-2H-chromen-4-ol (TSB) embracing chromone and benzoxazole moieties, for the recognition of diethyl chlorophosphate (DCP), a sarin gas surrogate, in both gaseous and solution phases, respectively. Upon adding DCP to the TSB solution in pure DMSO and 50% v/v water–DMSO mixture, there is an observable change from very pale yellow to colorless. Additionally, there is a transition from no fluorescence to intense blue-violet photoluminescence enhancement under exposure to a 365 nm UV lamp. These optical signals are found to be due to the development of phosphorylated TSB–DCP products, inhibiting intramolecular charge transfer (ICT) and the excited state intramolecular proton transfer (ESIPT) mechanism involved in TSB. The developed sensor demonstrated the ability to detect DCP even in the presence of various other challenging guest analytes, achieving a recognition and quantification limit in the μM range. Furthermore, to achieve on-site detection of DCP and investigate the practical utility of the developed probe, we have demonstrated the use of a paper strip-based test kit, the “dip-stick” method, and, notably, conducted real sample analysis on spiked soil samples.

Flavonoids are naturally occurring oxygen-containing heterocyclic systems with unique properties for diverse applications. The present study reports the synthesis of a new 2′-benzyloxy flavone and explores its fluorescence sensing properties towards secondary chemical explosives, such as picric acid, and pH sensing. The target 2′-benzyloxy flavone fluorophore (5) was synthesized in three-step reactions with good yield and was fully characterized using NMR, FTIR spectroscopy, and HRMS. The sensing propensity of 5 towards nitroaromatics and pH was probed using fluorescence spectroscopy. Compound 5 exhibited a preferential sensing property for phenolic nitroaromatics with high quenching efficiency for picric acid and differential fluorescence responses for different pH. The superior selectivity of 5 for picric acid is attributed to the intermolecular hydrogen bonding interactions between the O atoms in 5 and the OH groups of picric acid. The observed experimental results were further validated by computational calculations which strongly supported the hydrogen-bond-driven sensing selectivity. Furthermore, selective sensing of picric acid by 5 was further demonstrated in real-water samples and using paper-based sensing. These studies make compound 5 a potential dual sensor for selective sensing of picric acid and sensing of pH of the medium.

Excited-state intramolecular proton transfer (ESIPT) emitters are unique in that the emission is significantly red shifted relative to the absorption spectra. Herein we explore the effect of substituents on the ability of thin films of 2-[1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl]phenol-based ESIPT reporter compounds to detect hydrogen fluoride found in G-series nerve agents containing a phosphonofluoridate moiety. When the hydroxyl group of the 2-[1-phenyl-1H-phenanthro[9,10-d]imidazol-2-yl]phenol-based reporter compounds was protected as a silyl ether the photoluminescence emission spectra had vibrational structure and emission maxima at around 370 nm. The silyl protecting groups could be cleaved upon exposure to hydrogen fluoride in the G-series nerve agent simulant, di-iso-propyl fluorophosphate, leading to ESIPT emission with a peak maximum at around 470 nm, thus allowing identification of the presence of hydrogen fluoride. Films of the sensing materials with the different silyl protecting groups were found to have different stabilities to ambient conditions and reactivity with hydrogen fluoride, with the larger silyl ethers such as triethylsilyl and t-butyldimethyl silyl performing better overall when compared to the smaller trimethylsilyl ether. Steric encumberance or addition of polar solubilising groups was found to reduce the sensing capability. The optimal sensing material was lipophilic and contained a t-butyldimethyl silyl protecting group, with films capable of detecting hydrogen fluoride at a concentration of 0.1 ppm which, based on a sarin purity of 99%, would enable sarin to be detected at 1.2 ppm, which is below the LC₅₀ five minute exposure limit for sarin of 1.6–3.2 ppm.

Optical fiber biosensors based on the surface plasmon resonance (SPR) phenomenon are generating increasing interest due to their capability of real-time monitoring of analytes in a biocompatible, label-free, stable, and cost-effective manner. In fact, SPR optical fiber biosensors are becoming very popular in environmental science, clinical diagnosis, disease detection, and food safety. This review provides a comprehensive overview of optical fiber biosensors that utilize SPR. The principles and recent developments of optical fiber sensors are described. Different SPR optical fiber biosensors, including traditional optical fiber SPR biosensors, microstructured optical fiber (MOF) biosensors, grating-assisted plasmon fiber SPR biosensors, and others, are reviewed and the capabilities of common biosensors are compared. This overview aims to provide guidance for future research and development of this important and burgeoning field.

Liver disease in dogs is a major cause of morbidity and mortality. Non-invasive diagnosis of liver disease in dogs is a clinical challenge and improved tests which could done at point-of-care are highly desirable. Liver-specific circulating microRNAs have emerged as promising biomarkers for liver injury across many vertebrate species including dogs. MicroRNA-122 (miR-122), originating from the damaged hepatocytes, provides high specificity and sensitivity in detecting liver disease, compared to the traditional biomarkers. In this study, we present the development of a point-of-care compatible electrochemical biosensor for rapid, early diagnosis of liver disease in dogs by detecting miR-122 in clinical samples. Building on our prior work utilising electrochemical impedance spectroscopy (EIS) for direct and amplification-free detection of miR-122 in human drug-induced liver injury, we have used a miR-122 target-specific short probe and implemented target overhang formation during hybridisation in a flow-based sample cycling setup for enhanced detection performance and demonstrated its performance in real clinical dog samples for the first time. We determined the hybridisation performance by analysing miR-122 specificity and sensitivity achieving a limit of detection (LOD) and limit of quantification (LOQ) of 10 pM and 100 pM, respectively, and high specificity over a nearly-complementary sequence of a miR-122 precursor. Using conventional sample preparation, the developed EIS assay was used to analyse serum samples from dogs with liver disease which were identified based on an increased serum alanine aminotransferase concentration. The test successfully distinguished samples from dogs with and without liver disease in comparable performance to the gold-standard real-time polymerase chain reaction (qPCR) detection. We will further focus on developing sample-to-answer test by combining our miR-122 EIS biosensor with a compatible sample preparation to measure miR-122 from dog blood at point of care.

Point of care (POC) diagnostic devices provide a method for rapid accurate identification of disease through analysis of biologically relevant substances. This review focuses on the utility of POC testing for early detection of periodontitis, a critical factor in treating the disease. Accessing the oral cavity for biological sampling is less invasive when compared to other internal test sites, and oral fluids contain biomarkers indicative of periodontitis. The ease of access makes the mouth an excellent target location for the development of POC devices. In this review, accepted standards in industry by which these devices must adhere, provided by the World Health Organization such as REASSURED and CLIA, are discussed. An overview is provided for many periodontal biomarkers currently being investigated as a means of predicting periodontal disease and its progression. POC devices currently being investigated for the identification and monitoring of periodontal disease such as paper-based and lab-on-a-chip based devices are outlined. Limitations of current POC devices on the market are provided and future directions in leveraging biomarkers as an adjunctive method for oral diagnosis along with AI-based analysis systems are discussed. Here, we present the ESSENCE sensor platform, which combines a porous non-planar electrode with enhanced shear flow to achieve unprecedented sensitivity and selectivity. The combination of the ESENCE chip with an automated platform allows us to meet the WHO's ASSURED criteria. This platform promises to be an exciting POC candidate for early detection of periodontitis.

Magneto-plasmonic nanosystems have emerged as important multifunctional structures for several sensing applications, including on-site water quality monitoring. In this scenario, these nanosystems can integrate magnetic assisted separation procedures associated with optical detection of water contaminants, by exploring the surface-enhanced Raman scattering effect (SERS). Among the several modalities proposed for such magneto-plasmonic nanosystems, bionanocomposite particles have not been explored in this context. Hence, this research introduces bionanocomposites comprising magnetite cores that have been coupled to Au nanoparticles (NPs) via an intermediate surface modification step using hybrid shells of trimethyl chitosan-SiO₂. The magnetic bionanocomposites were decorated with Au NPs by exploring two methods: their assembly with pre-synthesized Au colloids and as heterogeneous substrates for the in situ synthesis of Au NPs. The resulting magneto-plasmonic nanosystems are responsive to an external magnetic gradient and show the localized surface plasmon resonance (LSPR) band ascribed to the Au NPs. Therefore, such multifunctionality was explored here by assessing the SERS performance of the magneto-plasmonic substrates after their use as magnetic nanosorbents for the uptake of organic dyes, specifically methylene blue (MB) and rose bengal (RB), as water contaminant models. The results showed that both types of substrates are effective, though the ex situ bionanocomposites have shown better SERS activity. As such, the latter have been selected to further demonstrate the versatility of the bionanocomposites for the SERS detection of other types of water contaminants, such as salicylic acid (SA), a pharmaceutical compound that is classified as a teratogen substance. Overall, these findings indicate that magneto-plasmonic bionanocomposites, indeed can be explored as more sustainable platforms for analytical purposes, combining the ability for magnetic separation and SERS trace detection.