Sensors & diagnostics最新文献

A novel alternative to cope with saliva-to-saliva variations and cross-interference while sensing delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) is reported here using two voltammetric sensors coupled with machine learning. The screen-printed electrodes modified with the same analyte molecules (m-Z-THC and m-Z-CBD) were employed for sensing ultra-low concentrations of THC and CBD in the 0 to 5 ng mL⁻¹ range in real human saliva samples. Simultaneous detection of THC and CBD was carried out using m-Z-THC or m-Z-CBD to study the performance of each modified sensor. Also, CBD and THC have the same molecular structure; there is only a slight difference in how the atoms are arranged, and therefore both molecules will have similar electrochemical performance. Consequently, CBD can be a potential interference while detecting THC and THC can be an interference during CBD detection using electrochemical sensors. Therefore, machine learning was introduced to analyze the sensor analytical responses to overcome such issues. The data processing results provide suitable accuracies of 100% for training in the case of both sensors and 92 and 83% for m-Z-THC and m-Z-CBD, respectively, for dataset testing THC and CBD in saliva samples. Additionally, the saliva samples containing CBD and THC as cross-interference were accurately identified and classified.

MicroRNAs (miRNAs) are short (about 18–24 nucleotides) non-coding RNAs and have emerged as potential biomarkers for various diseases, including cancers. Due to their short lengths, the specificity often becomes an issue in conventional amplification-based methods. Next-generation sequencing techniques could be an alternative, but the long analysis time and expensive costs make them less suitable for routine clinical diagnosis. Therefore, it is essential to develop a rapid, selective, and accurate miRNA detection assay using a simple, affordable system. In this work, we report a CRISPR/Cas13a-based miRNA biosensing using point-of-care dark-field (DF) imaging. We utilized magnetic-gold nanoparticle (MGNPs) complexes as signal probes, which consist of 200 nm-sized magnetic beads and 60 nm-sized gold nanoparticles (AuNPs) linked by DNA hybridization. Once the CRISPR/Cas13a system recognized the target miRNAs (miR-21-5p), the activated Cas13a cleaved the bridge linker containing RNA sequences, releasing 60 nm-AuNPs detected and quantified by a portable DF imaging system. The combination of CRISPR/Cas13a, MGNPs, and DF imaging demonstrated amplification-free detection of miR-21-5p within 30 min at a detection limit of 500 attomoles (25 pM) and with single-base specificity. The CRISPR/Cas13a-assisted MGNP-DF assay achieved rapid, selective, and accurate detection of miRNAs with simple equipment, thus providing a potential application for cancer diagnosis.

Point-of-care (POC) biosensors have enormous potential to help guide and inform clinical decisions at a patient's location. They are particularly relevant to underserved populations, and people living in remote locations where healthcare infrastructure and resources are often limited. The translation of effective POC biosensors into commercial products is rapidly growing across many research fields. A significant quantity of scientific articles focused on the fundamental, applied, and proof-of-concept aspects of biosensing are reported each year. However, this extensive body of work is not reflected in the comparatively small number of commercial biosensors available on the market. Here, we discuss key aspects of the biosensor translation process including the selection of analytical biomarkers in various body fluids, clinical trials, regulatory approval, consumer engagement, manufacturing and scale-up strategies, health economics, and legal and ethical considerations.

This present work aimed to craft copper (Cu²⁺)-doped carbon dots (CuCDs) for the selective and sensitive detection of a guanine nucleobase. By employing a hydrothermal method, we synthesized blue-emitting CuCDs having emission maxima at 423 nm. CuCDs were used as a fluorescence turn-on ratiometric probe to detect guanine, a critical purine base in DNA involved in energy transduction, cell signalling, and metabolic processes. In the presence of guanine, the fluorescence intensity of CuCDs significantly increased due to the stable non-covalent interaction between Cu²⁺ and guanine. CuCDs achieved a very low limit of detection (LOD) of 0.59 nM for guanine as a highly sensitive probe. CuCDs demonstrated selectivity for guanine with no interference from other nucleobases (adenine, thymine, and cytosine) and various biomolecules and metal ions commonly found in the cellular environment. In addition, CuCDs demonstrated a higher affinity for guanine-enriched oligonucleotide cMYC G 27-mer over dsDNA 26-mer devoid of a large guanine population. Furthermore, the fluorescence intensity of CuCDs increased in guanine-treated mammalian cells and G-quadruplex-enriched cancer cells compared with that in non-cancerous cells. Hence, we developed a highly sensitive ratiometric fluorescence probe, CuCDs, for the selective detection of guanine both in vitro and within mammalian cells via a “fluorescence turn-on mechanism”.

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.