Sensors & diagnostics最新文献

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.

We investigate the influence of the correlation between different types of polarized light (linear and circular) and spin-polarization |P_s| (in %) on the effectiveness of a spin-based quantum dot-modified DNA device for a DNA hybridization sensor. The device exhibits a significant two-fold increase in |P_s| (in %) when exposed to circularly polarized (C.P.) light, in comparison to the state of no illumination. This improvement in |P_s| results in a significant ten-fold enhancement in the limit of detection (L.O.D.) of the electrode under C.P. light illumination, surpassing the conditions without illumination and even achieving a two-fold increase compared to linearly polarized (L.P.) light illumination. These results emphasize the crucial significance of polarized light in maximizing the efficiency of spin-based DNA hybridization sensors. The significant enhancements in the performance observed under C.P. light illumination demonstrate the potential use of our device to function as a highly sensitive and efficient tool in spin-based bio-sensing applications.

A novel triphenylamine benzimidazole based fluorogenic chemosensor named (2E,2′E)-3,3′-((phenylazanediyl)bis(4,1-phenylene))bis(2-(1H-benzo[d]imidazol-2-yl)acrylonitrile) (PBIA) has been successfully generated and characterized by varoius spectroscopic techniques. Among various screened anions, only cyanide (CN⁻) showed a distinct fluorogenic property towards PBIA. Hence, the optical properties of PBIA were investigated in the presence of cyanide (CN⁻) by means of UV-vis spectrophotometry and fluorescence spectroscopy in DMSO, where we observed that, upon treatment with CN⁻ to the probe solution, the orange fluorescence of the ligand showed a blue shift and the orange fluorescence changed to greenish-yellow under an UV lamp. The hypsochromic shift in fluorescence maxima upon the addition of cyanide was attributed to nucleophilic addition of cyanide to PBIA inhibiting the electron flow within the molecule and disrupting the ICT process. The interaction behind the sensing of cyanide was investigated by ¹H-NMR titration, a mass spectroscopic study and DFT calculations, which supported the mechanism. The limit of detection (LOD) was calculated and found to be in the order of 10⁻⁸ (M). PBIA showed an immediate response in the spectral pattern (<20 s) towards its target cyanide ion, and the effectiveness of the chemosensor was also examined in the presence of competing anions. Furthermore, the practical efficacy of the PBIA was established by a dipstick experiment along with cyanide detection in various natural water resources. Human breast cancer cells MDA-MB 231 were made susceptible to CN⁻ sensing in a biological system.

Herein, we report the bioconjugation of anti-prostate-specific antigen polyclonal antibodies (pAb) onto the fluorescein-doped silica nanoparticles to detect prostate-specific antigen (PSA). Fluorescein-isothiocyanate (FITC), a fluorescent dye, was reacted with (3-aminopropyl)triethoxysilane (APTES) to form the FITC-APTES organosilane precursor. FITC-APTES was mixed with tetraethoxysilane (TEOS) to form fluorescent silica nanoparticles (FITC@SiO₂NPs) containing 3% and 6% of dye loading. The silica nanoparticles prevented the dye from leaching and promoted the fluorescent signal amplification for the detection of PSA. Phenylboronic acid (PBA) was coated onto the fluorescent silica nanoparticles for the oriented antibody immobilization via the boronate ester to form FITC@SiO₂-PBA-pAb. The fluorescent silica nanobioconjugates exhibited an emission peak at 518 nm, which was stable over time. A fluorescence sandwich-type immunoassay was used for the detection of PSA using FITC@SiO₂-PBA-pAb. Alkaline hydrolysis of the sensing nanobioconjugates afforded enhanced sensitivity by releasing FITC molecules. In buffer samples, the fluorescent immunosensor exhibited a linear correlation range from 2.0 pg mL⁻¹ to 50 ng mL⁻¹. The linear range was from 2.0 pg mL⁻¹ to 100 ng mL⁻¹ in newborn calf serum (representing real samples). The limit of detection (LOD) was 8.25 fg mL⁻¹ with a limit of quantification (LOQ) of 27.2 fg mL⁻¹ in PBS (pH 7.4) after NaOH dissolution. A fluorescence immunosensor was used to detect PSA in spiked newborn calf serum with NaOH dissolution. It exhibited an LOD value of 33.0 fg mL⁻¹ and LOQ value of 0.109 pg mL⁻¹. The developed fluorescence immunosensor showed high selectivity and specificity for PSA. The detection of prostate-specific antigen in newborn calf serum samples exhibited no matrix interferences.