Sensors & diagnostics最新文献

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.

Spermine is a vital biomarker for clinical diagnosis of cancer and estimating food spoilage. Here, supramolecular assemblies of two donor–π–acceptor dipods R-SPM (λ_em 640 nm) and NIR-SPM (λ_em 720 nm) with SDS have been discovered for the detection of spermine and spermidine under physiological conditions at nanomolar levels. The addition of SDS to R-SPM and NIR-SPM results in the formation of self-assemblies (DLS, zeta-potential and UV-vis studies) with no significant change in their fluorescence but further addition of spermine/spermidine to the R-SPM∩SDS and NIR-SPM∩SDS assemblies results in a 30–80 fold increase in fluorescence intensity, respectively at 640 nm and 720 nm. The LOD for spermine and spermidine detection is 22 nM (4.4 ppb) and 67 nM (9.7 ppb). The ensembles show nominal interference from other biogenic amines, amino acids, metal ions, and anions. Both R-SPM∩SDS and NIR-SPM∩SDS ensembles can be stored in the dark for >3 months without affecting their performance. The potential of these ensembles for real world applications like analysis of spermine in urine, human serum and food spoilage in the case of cheese, mushrooms, chicken and mutton has been demonstrated. The smartphone relied RGB analysis facilitates the on-site determination of spermine in food samples.

The electrochemical aptamer-based (EAB) sensor platform is the only molecular monitoring approach yet reported that is (1) real time and effectively continuous, (2) selective enough to deploy in situ in the living body, and (3) independent of the chemical or enzymatic reactivity of its target, rendering it adaptable to a wide range of analytes. These attributes suggest the EAB platform will prove to be an important tool in both biomedical research and clinical practice. To advance this possibility, here we have explored the stability of EAB sensors upon storage, using retention of the target recognizing aptamer, the sensor's signal gain, and the affinity of the aptamer as our performance metrics. Doing so we find that low-temperature (−20 °C) storage is sufficient to preserve sensor functionality for at least six months without the need for exogenous preservatives.

Correction for ‘Highly sensitive solid-state nanopore aptasensor based on target-induced strand displacement for okadaic acid detection from shellfish samples’ by Mohamed Amin Elaguech et al., Sens. Diagn., 2023, 2, 1612–1622, https://doi.org/10.1039/D3SD00199G.

In this report, ion current rectification, an electrochemical phenomenon observed in asymmetric nanopipettes, is used for the label-free detection of SARS-CoV-2 viral fragments in nasopharyngeal samples. Quartz nanopipettes are functionalized with aptamers targeting the spike protein S1 domain, wherein changes to the surface charge magnitude, distribution, and ion transport behavior modulate the current–voltage response upon binding. The aptamer-modified nanopipette provides a selective and sensitive method for detecting SARS-CoV-2, with a limit of detection in the laboratory of 0.05 pg mL⁻¹. The effectiveness of this low-cost platform was demonstrated by sensing SARS-CoV-2 in nasopharyngeal samples, successfully discriminating between positive and negative cases with minimal template preparation, highlighting the platform's potential as a versatile sensing strategy for infectious disease detection in clinical diagnosis.

Breathomics involves the use of non-invasive methods for diagnosing asthma by analyzing exhaled breath. While significant progress has been made in applying this approach to adult asthma, extending its application to pediatric asthma is crucial due to the increasing concern in this population. This review delineates five potential clinical applications: asthma diagnosis, differential diagnosis of asthma, assessment of asthma control levels, prediction of asthma exacerbation, and asthma phenotyping. Additionally, it highlights the moderate to reasonable predictive accuracy of exhaled breath volatile organic compounds (VOCs) breathomics in childhood asthma. However, it acknowledges that this field is still in its nascent stage of development, with particularly limited data available for Asian populations. Moreover, the identification of VOC biomarkers in pediatric asthma patients remains inconclusive, with varying reports. Therefore, large-scale data collection and standardization are imperative. Refinement and methodological improvements are necessary before integrating breathomics into clinical practice. This article provides clear directions for future research to optimize the clinical applicability of breathomics in evaluating asthma in children.

Technological advancements are revolutionizing diabetic care worldwide, particularly in the realm of glucose monitoring. Traditionally invasive and cumbersome, glucose monitoring is shifting towards less invasive methods, enhancing patient quality of life and reducing risks associated with hypo- and hyperglycemia. Wearable biosensors, focusing on sweat and interstitial fluid, offer novel avenues for early disease detection and personalized point-of-care testing. This review paper provides a comprehensive overview of recent strides in wearable sweat sensors, including historical perspectives, electrochemical sensing mechanisms, material advancements, and the role of nanomaterials in enhancing sensor performance. By examining the evolution of glucose monitoring devices and highlighting commercially available devices, the review underscores the wide-ranging utility of electrochemical sensors in glucose monitoring. Enzymatic and non-enzymatic sensing mechanisms, potentiometric, amperometric/voltammetric sensors, ion-selective electrodes, and biosensors are discussed in detail, alongside various materials employed to optimize sensor performance. The burgeoning interest in nanomaterial-enabled sensor platforms signifies a promising future for sweat-based glucose monitoring, with potential implications for personalized healthcare and disease management.

With the coronavirus pandemic, companies and governments around the world have been investing millions of dollars in the development of contactless sensor technologies that minimize the need for physical interactions between patients and healthcare providers. This has led to rapid progress in healthcare research on innovative contactless technologies, particularly for infants and elderly individuals with chronic diseases that require continuous, real-time monitoring and control. The combination of sensing technology and wireless communication has emerged as a promising research area, as patients often find it unpleasant or anxiety-provoking to wear sensor devices, and physical contact can exacerbate the spread of contagious diseases. To address these issues, research has focused on sensor-less or contactless technology to send and analyse wireless signals to remotely monitor and measure vital signs without requiring physical contact or sensor devices. Herein, we have provided a comprehensive survey and study of non-invasive/contactless vital sign monitoring systems, particularly the heart rate and the respiration rate monitoring systems to achieve accurate and reliable measurements. We have found that there is a lack of a comprehensive comparison and analysis over existing contactless vital sign monitoring systems. Therefore, we first present and classify the existing non-invasive monitoring designs based on their approaches and techniques, and then compare them based on the performance and accuracy.