Search Results (1,710)

The precise and fast detection of heparin, the most widely used anticoagulant, remains a significant challenge for assessing its use in a clinical setting. In this work, we adapt a well-established asymmetric cyanine fluorogenic platform for the purpose of ultrasensitive heparin detection in the presence of common interferant chemical species. Three analogous fluorescence probes are synthesized in order to optimize for the number of binding moieties. Their interaction with heparin is studied using steady-state absorption, fluorescence, and circular dichroism spectroscopy. The obtained probes exhibit a highly sensitive “turn-on” fluorescence response to heparin, with a LOD in the 10–25 nM range, well within practical requirement, as well as a visible colorimetric change. The heparin–probe complex is also employed as a sensitive detection platform for protamine, both in the “turn-off” fluorescence and ratiometric detection schemes. Full article

Biomarker detection is imperative in the realms of modern medicine, biology, and environmental science, owing to the numerous avenues for its application. The recent scientific upsurge in the development of molecules, materials, and mechanisms for such scientific development has garnered considerable attention among scientists. In this connection, excited-state intramolecular proton transfer (ESIPT) properties of photoluminescent compounds provide considerable insights into the designing, development, and detection of biomarkers. ESIPT molecules significantly show a Stokes-shifted emission due to their sensitive nature and unique photophysical properties. Leveraging this photophysical property and tunable nature, several fluorescent probes of this genre can be designed and synthesized for a plethora of application spheres. Schiff bases encompass one such category of functional molecules displaying ESIPT properties, which can be mitigated by adding several other functionalities and desired optical characteristics. The current review article spans the basics of ESIPT properties of certain photoluminescent molecules and also envisages biosensing applications of recently developed imine–functionalized Schiff base molecules with such properties as the prima-foci, along with other applications. Full article

A copper-based nanoenzyme (Cu-BL) co-modified by L-L-lysine and 2-2-amino terephthalic acid has laccase-like activity and fluorescence characteristics. Based on this, a colorimetric and fluorescent dual-mode sensor was developed to visually and quantitatively detect tetracycline antibiotics (TCs), including tetracycline (TC), chlortetracycline (CTC), and oxytetracycline (OTC). In the colorimetric detection system, TCs can inhibit the generation of singlet oxygen (¹O₂) and weaken the ability of 2,4-dichlorophenol (2,4-DP) to be oxidized into pink-colored quinone substances. The linear ranges are 0.5–80 μM, 1–80 μM, and 0.25–80 μM, and the detection limits are 0.27 μM, 0.22 μM, and 0.26μM, respectively. In addition, due to the inner filter effect, tetracycline antibiotics can interact with Cu-BL, and with the increase in tetracycline antibiotic concentration, the fluorescence intensity will decrease. In addition, the smartphone sensing platform is combined with the colorimetric signal for the rapid and visual quantitative detection of tetracycline antibiotics. Generally speaking, the colorimetric/fluorescence dual-mode sensor demonstrates good stability, high specificity, and strong anti-interference capabilities, highlighting its practical application potential. This work is expected to offer novel insights for the development of multifunctional nanoenzymes and the integration of a multi-mode sensing platform. Full article

Natural medicines play an indispensable role in treating thrombotic-related diseases and a thorough investigation of their material basis is crucial for medicine development. The rapid advancement in medicine-active component screening technologies has paved new avenues for studying natural medicines, holding significant theoretical and practical value. This review focuses on the application progress of multimodal screening technologies, including high-throughput screening, chip technology, molecular biology methods, fluorescence sensors, and computational biology, in the screening of anticoagulant medicines. The aim is to provide a reference framework for screening and validating active components in natural medicines. The early application of these technologies can swiftly assess the safety and efficacy of medicines, accelerating the medicine development process and reducing the failure rate in clinical trials. Nonetheless, the overall mechanisms of action of natural medicines and the correlation between their chemical components and thrombotic diseases remain challenging areas that require further in-depth exploration and technological innovation. Full article

ZnO/MO_x (M = Fe^III, Co^II,III, Ni^II, Sn^IV, In^III, Ga^III; [M]/([Zn] + [M]) = 15 mol%) nanofiber heterostructures were obtained by co-electrospinning and characterized by X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectroscopy. The sensor properties of ZnO and ZnO/MO_x nanofibers were studied toward reducing gases CO (20 ppm), methanol (20 ppm), acetone (20 ppm), and oxidizing gas NO₂ (1 ppm) in dry air. It was demonstrated that the temperature of the maximum sensor response of ZnO/MO_x nanofibers toward reducing gases is primarily influenced by the binding energy of chemisorbed oxygen with the surface of the modifier’s oxides. When detecting oxidizing gas NO₂, high sensitivity at a low measurement temperature can be achieved with a high concentration of free electrons in the near-surface layer of zinc oxide grains, which is determined by the band bending at the ZnO/MO_x interface characterized by the difference in the electron work function of ZnO and MO_x. Full article

This article analyzes the prospects for the appearance of paper-based sensors on the sensor market. It is concluded that paper-based sensors are not a fantasy but a reality. It is shown that paper has properties that make it possible to develop a wide variety of paper-based sensors, such as SERS, colorimetric, fluorescent, conductometric, capacitive, fiber-optic, electrochemical, microfluidic, shape-deformation, microwave, and various physical sensors. The use of paper in the manufacturing of various sensors opens up new possibilities both in terms of new approaches to their manufacturing and in terms of new areas of their application. However, it must be recognized that for the widespread use of paper and the appearance of paper-based sensors on the sensor market, many obstacles must be overcome. Full article

Compared to natural enzymes, the development of efficient artificial simulated enzymes, such as those based on bimetallic materials with high catalytic activity and good stability, is an important way until now. Herein, we employed ZnCo₂O₄ microspheres as carriers to synthesize Pt-doped composites with different amounts using a one-pot method. The morphology and structure of the synthesized materials were characterized using XRD, SEM, BET, FT-IR, XPS, and Zeta potential techniques. It was found that Pt⁰ adhered well to the surface of ZnCo₂O₄ microspheres, with a 12.5% Pt doped ratio exhibiting abundant oxygen vacancies, excellent substrate affinity, and high peroxidase-like activity. Using fluorescent probes and electrochemical methods, the peroxidase-like catalytic mechanism has been explored that Pt@ZnCo₂O₄ microspheres can accelerate the electron transfer between H₂O₂ and 3,3′,5,5′-tetramethylbenzidine (TMB). Based on the optimal loading ratio of 12.5% of Pt@ZnCo₂O₄, a colorimetric sensor for visual detection of L-cysteine (L-Cys) was constructed, exhibiting a wide linear range of 0.1~50 µM and a low detection limit of 0.0163 µM. The sensor possesses good selectivity, reusability, and usage stability, which can be well applied to the determination of L-Cys in health product capsules with recovery rates of 96.9%~103.7% and RSD of 1.07%~6.50%. This work broadens the application prospects of spinel materials such as ZnCo₂O₄ in the field of biological analysis and also provides inspiration for the development of new artificial simulated enzymes. Full article

Continuous glucose monitoring based on the minimally invasive implantation of glucose sensor is characterized by high accuracy and good stability. At present, glucose concentration monitoring based on fluorescent glucose capsule sensor is a new development trend. In this paper, we design a fluorescent glucose capsule sensor with a design optimization study. The motion trajectory of incident light in the fluorescent gel layer is simulated based on the Monte Carlo method, and the cloud maps of light intensity with the light intensity distribution at the light-receiving layer are plotted. Altering the density of fluorescent molecules, varying the thickness of tissue layers, and adjusting the angle of incidence deflection, the study investigates the influence of these parameter changes on the optimal position of reflected light at the bottom. Finally, the simulation results were utilized to design and fabricate a fluorescent glucose capsule sensor. Rabbit subcutaneous tissue glucose level tests and real-time glucose solution concentration monitoring experiments were performed. This work contributes to the real-time monitoring of glucose levels and opens up new avenues for research on fabricating glucose sensors. Full article

Lead (Pb) is a highly toxic heavy metal that causes significant health hazards and environmental damage. Thus, the detection and removal of Pb²⁺ ions in freshwater sources are imperative for safeguarding public health and the environment. Moreover, the transformation of single resources into multiple high-value products is vital for achieving sustainable development goals (SDGs). In this regard, the present work focused on the preparation of two efficient materials, i.e., biochar (R-BC) and carbon dots (R-CDs) from a single resource (rice straw), via a novel approach by using extraction and hydrothermal process. The various microscopic and spectroscopy techniques confirmed the formation of porous structure and spherical morphology of R-BC and R-CDs, respectively. FTIR analysis confirmed the presence of hydroxyl (–OH), carboxyl (–COO) and amine (N–H) groups on the R-CDs’ surface. The obtained blue luminescent R-CDs were employed as chemosensors for the detection of Pb²⁺ ions. The sensor exhibited a strong linear correlation over a concentration range of 1 µM to 100 µM, with a limit of detection (LOD) of 0.11 µM. Furthermore, the BET analysis of R-BC indicated a surface area of 1.71 m²/g and a monolayer volume of 0.0081 cm³/g, supporting its adsorption potential for Pb²⁺. The R-BC showed excellent removal efficiency of 77.61%. The adsorption process followed the Langmuir isotherm model and second-order kinetics. Therefore, the dual use of rice straw-derived provides a cost-effective, environmentally friendly solution for Pb²⁺ detection and remediation to accomplish the SDGs. Full article

The aim of this study is to verify the possibility of detecting oil in the bottom sediment using a fibre optic system. The presence of oil is assessed on excitation–emission spectra obtained from spectral fluorescence signals of the sediment sample. A factory spectrofluorometer coupled with an experimental fibre optic measurement system was used. During the determination of spectra, the fibre optic system is set at a 45° angle to the sediment surface and placed above its surface. The light exciting the fluorescence and the light emitted by the sediment are transmitted in a combined bundle of fibre optic threads. The analysis of excitation–emission spectra of sediments contaminated with oil shows variability of the shapes of fluorescence spectra depending on the type and degree of oil contamination, which indicates the feasibility of the sensor design for detecting oil in the sediment in situ. Full article

Phosphorus-containing fluorophores provide a versatile framework for tailoring photophysical properties, enabling the design of advanced fluorogenic materials for various applications. Boron dipyrromethene (BODIPY) and squaraine dyes are of interest due to their multifaceted modularity and synthetic accessibility. Incorporating phosphorus-based functional groups into BODIPY or squaraine scaffolds has been achieved through a plethora of synthetic methods, including post-dye assembly functionalization. These modifications often influence key spectroscopic properties and molecular functionality by expanding their utility in bioimaging, sensing, photosensitization, and theranostic applications. By leveraging the tunable nature of phosphorus-containing moieties, these dyes hold immense promise for addressing current challenges in spectroscopy, imaging, and material designs while unlocking new opportunities for advanced functional systems in chemistry, biology, and medicine. Full article

Vibrio parahaemolyticus (V. parahaemolyticus) is a significant concern, as it can cause severe infections and hemolytic trauma. Given its prevalence in seawater and coastal seafood, it poses a substantial risk as a foodborne pathogen. Biosensor-based detection technology has been continuously evolving, and toehold switches have emerged as a promising area within it, especially in the detection of RNA viruses. Here, we have developed a cell-free toehold switch sensor for V. parahaemolyticus detection. Traditional toehold switch detection methods usually use green fluorescent protein (GFP) or enzyme LacZ as the output signal, with an incubation time as long as 2 h, and are also mainly applied to the detection of RNA viruses. In this study, we introduced a novel, artificially designed luciferase (LuxSit-i) as an output signal and constructed toehold switches with two different output signals (sfGFP, LuxSit-i), aimed at reducing the incubation time of toehold switches. Moreover, to further improve the detection process, we separately utilize recombinase polymerase amplification (RPA) and nucleic acid sequence-based amplification (NASBA) to amplify dead and live bacterial suspensions for detection and attempt to distinguish between dead and live bacteria. This study provided a convenient, rapid, and accurate method for the on-site detection of V. parahaemolyticus, especially beneficial for resource-limited settings. By eliminating the requirement for specialized facilities and personnel, this system has the potential to be a valuable tool in improving public health responses, especially in developing regions. Full article

Mycotoxins are a group of toxic metabolites produced by fungi that infect agricultural products. Consuming mycotoxin-contaminated foods and feeds can cause various adverse health effects in humans and animals. Therefore, developing rapid and sensitive analytical methods for detecting mycotoxins is an urgent task. The molecularly imprinted technique is an advanced analytical tool for the specific recognition and selective enrichment of target molecules. For the development of rapid detection methods for mycotoxins, synthesized molecularly imprinted polymers (MIPs) can serve as specific recognition elements. By integrating MIPs with various sensing platforms, such as solid-phase extraction, electrochemical sensors, fluorescence sensors, surface-enhanced Raman spectroscopy, and surface plasmonic resonance sensors, remarkable progress has been made in the detection of mycotoxins in foods. This review focuses on the advances in the application of MIPs for the rapid detection of various mycotoxins over the past five years. The development of new MIP synthesis methods is categorized and summarized. Moreover, the future potential of MIP-based methods for mycotoxin detection is also discussed and highlighted. Full article

The discriminative detection of volatile primary aliphatic diamines (VPADs) is a relevant and timely issue. This paper explores the distinctive optical features of H-type and J-type aggregates on paper-based (PB) films, namely H-PB and J-PB films, respectively, of a Lewis acidic Zn(salen)-type complex upon chemisorption of vapors of ditopic VPADs versus those of monotopic volatile amines. While volatile monotopic Lewis bases upon chemisorption give rise to mono-adducts accompanied by enhancement of the fluorescence, in contrast, VPADs act as ditopic bases forming di-adducts with distinct optical properties, leading to fluorescence quenching. This behavior enables the sensitive and discriminative detection of VPAD vapors from those of volatile monoamines. For example, for ethylenediamine (EDA), using J-PB films, sensitive detection is achieved with a LOD down to 6.6 ppm, lower than the OSHA permissible exposure limit of 10 ppm for EDA, and a linear dynamic range up to 100 ppm. Instead, H-PB films enable the detection of EDA vapors at higher ppm concentrations (up to 3000 ppm) with a linearity of up to 1000 ppm. Thus, the combination of both H-PB and J-PB films of the Zn(salen)-type complex represents a unique example of the sensitive and discriminative detection of EDA vapors in such a wide concentration range. Full article

Sprinkler irrigation is an effective method for protecting economic crops from frost damage; however, current research on its impacts is insufficient and lacks comprehensive evaluation. This research investigated the effects of sprinkler irrigation for frost protection on the air, soil, and tea plants in the tea garden. Sprinkler frost protection experiments were conducted in the tea garden, where temperature sensors measured the air and soil temperatures, and Monitoring-PAM was used to measure the chlorophyll fluorescence parameters (Fv/Fm) of the tea plants. The results indicated that lower initial ambient temperatures or smaller droplet sizes accelerate the rate of air temperature increase and slow the cooling rate. Under conditions of heavy frost, ice formation from irrigation water acts as an insulating layer, protecting the inter-row soil. Additionally, the Fv/Fm values of tea leaves protected by sprinkler irrigation ranged from 0.6 to 0.7, and were significantly higher than those of leaves exposed to frost damage. The results also showed that air and soil temperature and tea Fv/Fm can be used to perform a comprehensive assessment of sprinkler frost protection effectiveness. Full article