Sensors & diagnostics最新文献

Effective monitoring of ocular drugs is crucial for personalized medicine and improving drug delivery efficacy. However, traditional methods face difficulties in detecting low drug concentrations in small volumes of ocular fluid, such as that found on the ocular surface. In this study, we used capture-SELEX to select aptamers for two commonly used ocular drugs, timolol maleate and atropine. We identified TMJ-1 and AT-1 aptamers with binding affinities of 3.4 μM timolol maleate and 10 μM atropine, respectively. Our label-free TMJ-1 biosensor using thioflavin T staining achieved a limit of detection (LOD) of 0.3 μM for timolol maleate. The AT-1 biosensor showed an LOD of 1 μM for atropine, and exhibited a 10-fold higher sensitivity compared to UV-visible spectroscopy. Future research in this area holds promise in enhancing drug delivery monitoring and improving the treatment of ocular diseases.

The constant need for cancer diagnosis in the early stages drives the development of contrast agents and imaging methods. Imaging agents have important roles in monitoring the progression and metastasis of cancers. Antibodies as biomolecules in conjugation with nanoparticles, radioisotopes, and drugs have been used as biomarkers for the early diagnosis/therapy of cancers due to their serum stability, affinity, and specificity. While antibodies are commonly used as nuclear medicine biomarkers, antibody-based contrast agent platforms have recently gained attention in X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The developing antibody-based contrast agents have revolutionized cancer imaging techniques, particularly through MRI. Despite the promising advancements, some challenges and limitations need to be addressed for the extensive applications of these agents. Ongoing research is focused on overcoming challenges and limitations to enhance the efficiency and accuracy of these imaging methods. With continued advancements, antibody-based contrast agents hold immense potential in the early diagnosis and treatment of cancer. In this review, we summarize and categorize the recent progress in targeted imaging using antibody-based contrast agents by MRI and CT modalities.

Highly durable, stretchable, sensitive and biocompatible wearable strain sensors are crucial for healthcare, sports, and robotic applications. While strain sensor designs, fabrication and testing methods have been widely discussed by researchers, not many have discussed sensor improvements via implementing designs and protection layers that make the sensor more resilient. This paper will focus on sensor designs (straight line, U-shape, serpentine, and kirigami) and material selection that can provide better performance. Theoretical equations and calculations to indicate how the design shapes contribute to providing better performance are also included. An important aspect which is not often explored is having encapsulation layers which can significantly reduce the formation of cracks when the sensor is subjected to mechanical stress and bending. This review will include post-fabrication steps that are necessary to incorporate protection layers for wearable sensors. Due to the curvilinear shapes of wearable sensors that often need to be in close contact with human skin, reliability and durability testing often differs greatly from that of traditional strain sensors. Recent techniques for performance evaluation specific to wearable sensors such as cyclic stretching, bending, stretch till failure, washability, signal latency, and tensile tests were also discussed in detail. This includes experimental setup and duration of testing and its significance was described. To ensure device safety for the user, biocompatibility assessments need to be made. In this review, cytotoxicity test methods such as trypan blue, cell proliferation and MTT assay were compared and evaluated. By consolidating recent developments, this paper aims to provide researchers and practitioners with a comprehensive understanding of the advancements, and future directions in this rapidly evolving field.

Electrochemical aptamer-based (E-AB) sensors achieve detection and quantitation of biomedically relevant targets such as small molecule drugs and protein biomarkers in biological samples. E-ABs are usually fabricated on commercially available macroelectrodes which, although functional for rapid sensor prototyping, can be costly and are not compatible with the microliter sample volumes typically available in biorepositories for clinical validation studies. Seeking to develop a multi-point sensing platform for sensor validation in sample volumes characteristic of clinical studies, we report a protocol for in-house assembly of 3D-printed E-ABs. We employed a commercially available 3D stereolithographic printer (FormLabs, $5k USD) for electrochemical cell fabrication and directly embedded electrodes within the 3D-printed cell structure. This approach offers a reproducible and reusable electrode fabrication process resulting in four independent and simultaneous measurements for statistically weighted results. We demonstrate compatibility with aptamer sequences binding antibiotics and antineoplastic agents. We also demonstrate a proof-of-concept validation of serum vancomycin measurements using clinical samples. Our results demonstrate that 3D-printing can be used in conjunction with E-ABs for accessible, rapid, and statistically meaningful validation of E-AB sensors in biological matrices.

Monitoring of creatinine in human fluid has attracted considerable attention owing to the potential for diagnosis of chronic kidney disease. However, the detection of creatinine has been difficult owing to its electrochemical and optical inertness. In this approach, a highly selective and sensitive electrochemiluminescence (ECL) strategy based on homogeneous carbon quantum dots (CQDs) for the detection of creatinine was introduced. A copper(II) picrate complex was added at the surface of electrode to improve the selectivity of the sensor significantly by the formation of a Janovsky complex. A multi-pulse amperometric technique was applied as a very fast and reliable method for quantitative determination of creatinine. The calibration curve was acquired with a linear range from 1.0 × 10⁻⁸ to 1 × 10⁻⁵ M with a low detection limit of 8.7 × 10⁻⁹ M. The proposed creatinine sensing platform is experimentally very simple and shows high selectivity with a broad linear range of detection. Furthermore, the presented method can determine creatinine in real samples with excellent recoveries.

17β-Estradiol (E2) is one of the typical endocrine-disrupting compounds (EDCs), which plays a major role in facilitating the growth and regulating the balance of the human endocrine system. E2 contamination can cause environmental and health risks as E2 exposure can interfere with the endocrine system by binding to estrogen receptors. It is imperative to develop sensitive methods for E2 detection. Herein we developed a competitive enzyme-linked aptamer assay for E2 detection by using a newly reported high-affinity DNA aptamer as an affinity ligand. The complementary DNA (cDNA) of the anti-E2 aptamer is conjugated on a microplate. Horseradish peroxidase (HRP) is labeled on the aptamer probe. In the absence of E2, HRP-labeled aptamer is captured by cDNA, and HRP catalyzes the substrate into a product, generating an absorbance signal or chemiluminescence signal. In the presence of E2, E2 binds with the aptamer, causing displacement of HRP-labeled aptamer from the microplate and a decrease in signals. In absorbance-analysis mode, the detection limit of E2 reached 0.2 nmol L⁻¹ with a dynamic range from 0.2 nmol L⁻¹ to 20 μmol L⁻¹. In chemiluminescenceanalysis mode, this method enabled the quantification of E2 at 50 pmol L⁻¹, with a dynamic range from 50 pmol L⁻¹ to 50 μmol L⁻¹. This method could also detect E2 spiked in lake water samples, showing promise in practical applications.

Contact lenses offer a simple, cost-effective, and non-invasive method for in situ real-time analysis of various biomarkers. Electro-chemical sensors are integrated into contact lenses for analysis of various biomarkers. However, they suffer from rigid electronic components and connections, leading to eye irritation and biomarker concentration deviation. Here, a flexible and microfluidic integrated paper-based contact lens for colorimetric analysis of glucose was implemented. Facilitating a three-dimensional (3D) printer for lens fabrication eliminates cumbersome cleanroom processes and provides a simple, batch compatible process. Due to the capillary force of the filter paper, the sample was routed to detection chambers inside microchannels, and it allowed further colorimetric detection. The paper-embedded microfluidic contact lens successfully detects glucose down to 2 mM within ∼10 s. The small dimension of the microfluidic system enables detection of glucose levels as low as 5 μl. The results show the potential of the presented approach to analyze glucose concentration in a rapid manner. It is demonstrated that the fabricated contact lens can successfully detect glucose levels of diabetic patients.

Dual state emission luminogens (DSEgens) with strong fluorescence in both solution and solid states have extensive potential for numerous applications. Herein, a chroman-2,4-dione and indoline conjugate, 2, was synthesized for highly selective and sensitive turn-on fluorescent detection of cyanide ions. Compound 2 behaves as a molecular rotor and shows the dual state emission (DSE) phenomenon and multicolour emission. It displays bright fluorescence in both the concentrated solution and the solid-state. The compound is nonfluorescent in dilute solution, and with increasing concentration, it shows aggregation caused red-shifted emission. With increasing concentration, the emission colour changes from green to yellow to orange-red. The CC bond attached to the indoline moiety is a compelling target for nucleophilic addition. Cyanide ions reacted with the probe which remarkably changed the spectroscopic properties. With the gradual addition of cyanide, the colour of the probe solution was changed from yellow to colorless. The very weakly emissive probe 2 rapidly reacted with CN⁻ and emitted strongly due to the inhibition of internal charge transfer (ICT) from indoline to chroman-2,4-dione. The DSEgen properties and CN sensing were thoroughly investigated and supported using spectroscopic studies, TDDFT, and single-crystal X-ray diffraction.

Surface-engineered conducting polymers (CPs) have enabled technological advances in chemistry and materials science. Heterocyclic conjugated organic molecules, specifically indole and its derivatives, have the potential to be polymerized under electrochemically controlled conditions in different types of compatible solvent media, including self-assembled nanofluids, for several applications. Polymer-based electrode materials are valuable for the detection of various targeted biomolecules and other analytes. This review outlines the evolution of the electropolymerization technique in recent years, along with developments in the field. With advances in nanoscience, several materials have been used to modify CPs for electrochemical sensing. Several biomedical applications and the role of antifouling agents in the properties of several electropolymerized thin films are highlighted.

Malignant tumors are the second leading cause of human deaths worldwide, and early cancer screening and diagnosis can effectively reduce cancer mortality. Herein, we propose a new electrochemical method for the highly sensitive detection of MUC1-positive tumor cells based on proximity labelling-assisted multiple signal amplification. Specifically, a MUC1 aptamer-modified electrode was prepared for capturing MUC1-positive tumor cells, followed by binding of G4-DNA strands to the cells with the aid of a mild reduction reaction. A hemin/G4-DNA complex was then formed and acted as a mimic of horseradish peroxidase, catalysing the proximal labelling of tyramine-modified gold nanoparticles to induce silver-enhanced electrochemical signal amplification. Electrochemical results demonstrated that the method was able to specially identify MUC1-positive tumor cells and generate corresponding electrochemical responses in the range of 100 cells per mL to 1 × 10⁶ cells per mL with a detection limit of 21 cells per mL. Furthermore, the method displayed good stability and anti-interference performance in complex serum environments. Therefore, our work may provide an effective tool to improve the accuracy of cell-based tissue examination and liquid biopsy for early diagnosis of cancers in the future.