Environmental Monitoring Applications Research Articles

Colorimetric detection of Cu(II) in aqueous solutions using a novel chemosensor: 2-((2-chloroquinolin-3yl)methylidene]amino)phenol

ABSTRACT A spectrophotometric technique based on a selective colorimetric approach is presented in this study for the determination of Cu(II) ions using 2-([(2-chloroquinolin-3-yl)methylidene]amino)phenol (BHMOS) as a detection agent. NMR and FT-IR spectroscopy were used to characterize the compound thoroughly, ensuring accuracy in terms of its molecular structure. As a chemosensor in aqueous solutions, BHMOS has demonstrated a very high level of sensitivity and specificity, even in the presence of other cations. During the interaction between Cu(II) ions and BHMOS, a noticeable colour change was observed to pale green, which is a visual indicator of Cu(II) ions. The method demonstrated linearity for Cu(II) concentrations ranging from 5 to 60 µM, with a detection limit of 1.50 µM. The binding constant for the Cu(II)-BHMOS complex was determined to be 1.14 × 106 M−1, reflecting the strength and stability of the interaction. This method proved to be effective for detecting Cu(II) ions in both natural and simulated water samples, showing its potential utility in environmental monitoring applications.

Signal-enhanced electrochemical sensor employing MWCNTs/CMK-3/AuNPs and Au@Pd core-shell structure for sensitive determinationof AFB1 in complex matrix.

A sandwich electrochemical sensor was fabricated based on multi-walled carbon nanotubes/ordered mesoporous carbon/AuNP (MWCNTs/CMK-3/AuNP) nanocomposites and porous core-shell nanoparticles Au@PdNPs to achieve rapid and sensitive detection of AFB1 in complex matrices. MWCNTs/CMK-3/AuNP nanocomposite, which was prepared by self-assembly method, served as a substrate material to increase the aptamer loading and improve the conductivity and electrocatalytic activity of the electrode for the first signal amplification. Then, Au@PdNPs, which were synthesized by one-pot aqueous phase method, were applied as nanocarriers loaded with plenty of capture probe antibody (Ab) and signal molecule toluidine blue (Tb) to form the Au@PdNPs-Ab-Tb bioconjugates for secondary signal amplification. The sensing system could still significantly improve the signal output intensity even in the presence of ultra-low concentration target compounddue to the dual signal amplification of MWCNTs/CMK-3/AuNP nanocomposites and Au@PdNPs-Ab-Tb. The method exhibited high selectivity, low detection limit (9.13fg/mL), and strong stability to differentiate AFB1 from other mycotoxins. Furthermore, the sensor has been successfully applied to the quantitative determination of AFB1 in corn, malt, and six herbs, which has potential applications in food safety, quality control, and environmental monitoring.

Part-per-Billion (Ppb)-Level Acetylene Sensor Employing Optical Quartz Enhanced Photoacoustic Spectroscopy (QEPAS) with an Erbium-Doped Fiber Amplifier (EDFA) and a Fiber-Optic Fabry–Perot Interferometer

An all-optical double-pass quartz enhanced photoacoustic spectroscopy (QEPAS) sensor for the detection of acetylene (C2H2) at part-per-billion (ppb) levels was developed and experimentally validated. By employing an erbium-doped fiber amplifier (EDFA) capable of emitting up to 1 W of optical power, a commercial quartz tuning fork (QTF) resonating at 30.7 kHz, and double-pass acoustic microresonators, the amplitude of the QEPAS signal was significantly enhanced, thereby improving the sensitivity of the C2H2-QEPAS sensor. Instead of using piezoelectric detection in conventional QEPAS, a highly sensitive fiber-optic Fabry–Perot interferometer (FPI) was employed to measure the vibration of the QTF prong. A working point self-stabilizing technique was exploited to improve the demodulation sensitivity and stability. The linear response of the sensor to laser power and C2H2 concentration confirmed that no saturation occurred. With an excitation laser power of 1 W and a C2H2 absorption line of 1532.83 nm, a C2H2 minimum detection limit (MDL) of 19.1 ppb was achieved, corresponding to a normalized noise equivalent absorption coefficient (NNEA) of 1.58 × 10−8 cm−1∙W∙Hz−1/2. Owing to its high sensitivity, long-term stability, and immunity to electromagnetic interferences, the QEPAS sensor provides considerable potential for remote gas sensing in environmental monitoring and other applications.

Improved UV Photoresponse Performance of ZnO Nanowire Array Photodetector via Effective Pt Nanoparticle Coupling.

Ultraviolet (UV) photodetectors (PDs) based on nanowire (NW) hold significant promise for applications in fire detection, optical communication, and environmental monitoring. As optoelectronic devices evolve towards lower dimensionality, multifunctionality, and integrability, multicolor PDs have become a research hotspot in optics and electronic information. This study investigates the enhancement of detection capability in a light-trapping ZnO NW array through modification with Pt nanoparticles (NPs) via magnetron sputtering and hydrothermal synthesis. The optimized PD exhibits superior performance, achieving a responsivity of 12.49 A/W, detectivity of 4.07 × 1012 Jones, and external quantum efficiency (EQE) of 4.19 × 103%, respectively. In addition, the Pt NPs/ZnO NW/ZnO PD maintains spectral selectivity in the UV region. These findings show the pivotal role of Pt NPs in enhancing photodetection performance through their strong light absorption and scattering properties. This improvement is associated with localized surface plasmon resonance induced by the Pt NPs, leading to enhanced incident light and interfacial charge separation for the specialized configurations of the nanodevice. Utilizing metal NPs for device modification represents a breakthrough that positively affects the preparation of high-performance ZnO-based UV PDs.

Discrimination of VOCs with e-nose consisting of a single MEMS sensor using lightweight deep learning model based on SqueezeNet

The detection of volatile organic compounds (VOCs) has numerous applications in environmental monitoring and biomedicine. Metal oxide semiconductor (MOS) gas sensors are widely used in gas detection due to their simple structure, low fabrication cost, and fast response speed. However, MOS gas sensors have broad-spectrum responsiveness to VOCs, making selectivity a challenge. The most commonly used method to obtain selectivity is the E-nose system consisting of multiple sensors. However, the size of E-noses has increased due to the number of sensors with high power consumption and complicated signal processing. In recent years, deep learning has flourished, allowing for accurate discrimination of VOCs and concentration prediction using E-nose consisting of a single sensor. This method significantly reduces power consumption and facilitates portable applications. In this work, we synthesize SnO2-ZnO composite oxide and fabricate a E-nose consisting of a single MEMS gas sensor. The response performance of the E-nose to VOCs is stable with a high output signal-noise ratio (SNR). We design a lightweight deep learning model based on SqueezeNet and train it using transfer learning. Linear regression is used to predict the concentration of VOCs. Our work achieves accurate identification and low-error concentration prediction of VOCs, which is valuable for subsequent portable VOC detection systems.

Distributed semiconductor heterojunctions of ZnO–Cu2O for ultraviolet photodetection

Semiconductor heterojunctions, because of their unique optoelectronic properties, have gained significant attention for integrated photonic devices. UV photodetectors based on semiconductor heterojunctions are promising due to their enhanced light absorption, efficient charge separation, and tunable electronic properties, which collectively lead to superior sensitivity and performance. An inter-band transition-based UV photodetector utilizing Cu2O/ZnO distributed heterojunctions has been demonstrated. We propose an integrated photonic structure based on semiconductor heterojunctions in the form of Cu2O–ZnO grating for ultraviolet photodetection yielding a low dark current and improved efficiency. The Cu2O–ZnO grating heterostructure, in comparison to individual planar heterojunction, boosts light-matter interaction enabling higher absorption and enhanced responsivity. The device depicts a responsivity of 0.7A/W at 360nm wavelength. The device exhibits a broadband absorption which remains good over a broad wavelength range from 250nm to 450nm. The reported UV photodetector may find applications in environmental monitoring, UV light communication, biomedical diagnostics, and industrial safety.

Signal amplification strategy based on target-controlled release of mediator for ultrasensitive self-powered biosensing of acetamiprid

Self-powered biosensors with high sensitivity have garnered significant interest for their potential applications in the realm of portable sensing. Herein, a self-powered biosensor with a novel signal amplification strategy was developed by integrating target-controlled release of mediator with an enzyme biofuel cell for the ultrasensitive detection of acetamiprid (ACE). Zeolitic imidazolate framework-67 was utilized as both a nanocontainer for capturing the electron mediator 2,2′-azidobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and a precursor for the synthesis of cobalt nanoparticles/nitrogen, sulfur-codoped carbon nanotubes (Co NPs/NS-CNTs), which were employed as the electrode material for constructing both the glucose oxidase-based bioanode and the laccase-based biocathode. The target analyte ACE can specifically bind to its aptamer, leading to the release of ABTS, which cyclically participates in the catalytic reaction of the biocathode, thereby amplifying the electrochemical signal. By leveraging the benefits of ABTS cyclic catalysis and the effective electrocatalysis of bioelectrodes based on Co NPs/NS-CNTs, the self-powered biosensor has a broad detection range of 0.1-1000 fM and a low detection limit of 25 aM toward ACE. The proposed signal amplification approach presents a promising strategy for enhancing sensitivity and enabling portable analysis in applications of food safety, environmental monitoring, and medical diagnostics.

Highly transparent inorganic superhydrophilic coatings with sustainable anti-fogging and mechanically robust underwater anti-oil-fouling capabilities

Inorganic coatings with high transparency and superhydrophilicity have attracted tremendous attention because of their potential applications in marine environment monitoring, and oily wastewater treatment. However, the transparency and superhydrophilicity are usually mutually exclusive. Herein, we present a new facile strategy for fabricating highly transparent and mechanically robust superhydrophilic inorganic coatings with outstanding anti-fogging ability and anti-oil-fouling performance for high-viscosity oils. In this strategy, amorphous calcium phosphate (ACP) coatings are mineralized on the surface of polydopamine and polyethylenimine (PDA/PEI) membranes under the synergistic effect of magnesium ions, citric acid, and poly(acrylic acid) at room temperature, forming an organic-inorganic composite structure with a uniform texture on various substrates. Owing to the strong hydration capacity of ACP, these coatings are highly efficient at preventing surface fogging and avoiding underwater crude oil fouling. Meanwhile, the ACP coating without grain boundaries or pores can reduce light scattering, thus maintaining the high transparency of the substrate. Moreover, the organic-inorganic composite structure endows the coatings with robust mechanical properties. This PDA/PEI-ACP mineralized coating can be deposited on various substrates, showing potential applications in underwater optical lenses, oily wastewater treatment, microfluidic devices, and other areas.

Experimental analysis of low-duty cycle campus deployed IoT network using LoRa technology

This study emphases on the implementation and evaluation of a LoRa network in indoor environments through an experimental setup at Amity University, Greater Noida (AUGN) campus. Aimed at scrutinizing the link-level performance and reliability of LoRa technology, extensive measurements have been conducted with prototype device integrating the SX1278 LoRa radio module at 433 MHz. The performance has been analysed in terms of Signal-to-Noise Ratio (SNR), Received Signal Strength Indicator (RSSI), and Packet Reception Rate (PRR) across various line-of-sight (LoS) and non-line-of-sight (NLoS) scenarios. The results reveal that network performance is highly sensitive to parameter configurations, such as spreading factor (SF) and coding rate (CR). In LoS environments, SF = 9 and CR = 4/5 provided an RSSI of −89.12 dBm and an SNR of 9.91 dB, while highly obstructive areas saw optimal performance with SF = 7 and CR = 4/7. The study also identified configurations ensuring 100 % packet delivery accuracy and maximum throughput. This work stands out due to its thorough examination of LoRa for indoor IoT applications, notably addressing duty cycle restrictions, a topic often overlooked in existing literature. The valuable insights presented are crucial for maximizing the potential of LoRa in indoor environments with high population density. The findings strongly advocate for the use of LoRa for real-time environmental monitoring and innovative IoT applications within university campuses.

Recent advances in portable devices for environmental monitoring applications.

Environmental pollution remains a major societal problem, leading to serious impacts on living organisms including humans. Human activities such as civilization, urbanization, and industrialization are major causes of pollution. Imposing stricter rules helps control environmental pollutant levels, creating a need for reliable pollutant monitoring in air, water, and soil. The application of traditional analytical techniques is limited in low-resource areas because they are sophisticated, expensive, and bulky. With the development of biosensors and microfluidics technology, environmental monitoring has significantly improved the analysis time, low cost, portability, and ease of use. This review discusses the fundamentals of portable devices, including microfluidics and biosensors, for environmental control. Recently, publications reviewing microfluidics and biosensor device applications have increased more than tenfold, showing the potential of emerging novel approaches for environmental monitoring. Strategies for enzyme-, immunoassay-, and molecular-based analyte sensing are discussed based on their mechanisms and applications. Microfluidic and biosensor platforms for detecting major pollutants, including metal ions, pathogens, pesticides, and antibiotic residues, are reviewed based on their working principles, advantages, and disadvantages. Challenges and future trends for the device design and fabrication process to improve performance are discussed. Miniaturization, low cost, selectivity, sensitivity, high automation, and savings in samples and reagents make the devices ideal alternatives for in-field detection, especially in low-resource areas. However, their operation with complicated environmental samples requires further research to improve the specificity and sensitivity. Although there is a wide range of devices available for environmental applications, their implementation in real-world situations is limited. This study provides insights into existing issues that can be used as references and a comparative analysis for future studies and applications.

Design and performance of indium seals for size-constrained tunable laser spectrometers.

Indium seals have been used extensively in ultra-high vacuum and cryogenic applications. Typically, these seals use indium alongside or in place of other metal gaskets in stainless-steel vacuum flanges, with some custom applications for flanges sealing directly with glass (optics or tubes). Here, we present the design and performance of three pressed indium seals (99.99% In) between aluminum and 0.5 in. diameter sapphire optics and aluminum and gold coated Kovar semiconductor packages (TO-66 and TO-39). Test fixtures were designed to mimic those of future tunable diode laser spectrometers for Earth, planetary, and manned spaceflight environmental monitoring applications. Successful high-hermeticity seals [<10-10 atm cc/s (He)] were achieved for all seals formed with sufficient pressure applied to allow indium to flow between mating surfaces. The hermeticity of the seals was maintained after temperature cycling (-10 to +80 °C, 20 cycles), with the optical seals surviving extended duration tests (-55 to +85 °C, per MIL-STD-883). Semiconductor packages (TO-39) subjected to these extended tests saw a moderate increase in leak rate [∼5 × 10-9 atm cc/s (He)]; however, further testing showed that either the glass-metal package seals or the indium were affected (the sample size was too small to draw firm conclusions for future applications). Overall, these results suggest long-term survivability of indium seals for Kovar-aluminum and sapphire-aluminum interfaces [>10 years at 10-10 atm cc/s (He)], where the coefficient of thermal expansion differs by approximately four times.

Polymer enhanced sensitivity and figure of merit SPR optical fiber sensor for high refractive index and wide detection range

A highly sensitive sensor based on surface plasmon resonance (SPR) for high refractive index (RI) sensing is proposed, whose most unique feature lies in a high RI of polyvinylpyrrolidone (PVP) layer embedded between the optical fiber and Au film. The use of the high RI PVP layer amplifies the evanescent wave, thereby increasing sensitivity and improving figure of merit (FOM) of the SPR sensor. In addition, SPR sensor coated with a high RI PVP film breaks through the limitation that the inherent RI of optical fiber can only detect low RI, and can measure higher RI values and expand the measurement range. Experimental results demonstrate that, with a PVP layer thickness of 60 nm, showcasing superior performance compared to sensors lacking a PVP layer. Notably, this SPR sensor offers a cost-effective and straightforward fabrication process, promising broad application in environmental monitoring and biosensing.

Disposable electrochemical aptasensor with mesoporous carbon spheres modified screen-printed dual-working electrodes for Pb2+ and Hg2+ detection

Electrochemical biosensing combined with screen-printed paper technology provides an effective strategy for the quantitative analysis of metal ions, particularly suitable for in-situ determination. In this study, a disposable, economical and user-friendly screen-printed dual-working electrodes (SPDEs) aptasensor system for the determination of lead ions (Pb2+) and mercury ions (Hg2+) was described. The sensor system consists of dual-working electrodes, a counter electrode and a reference electrode fabricated using screen printing technology. The aptasensor demonstrates high sensitivity and selectivity towards Pb2+ and Hg2+, owing to the larger specific surface area (1334.7 m2/g) and excellent conductivity of mesoporous carbon nanoparticles (MCNs). Additionally, the specific recognition ability and high affinity of G-quadruplex and T-Hg2+-T structures for Pb2+ and Hg2+, respectively, further enhance the performance. Under optimized experimental conditions, the aptasensor achieves a low limit of detection (LOD) of 0.088 ng/mL for Pb2+ and 0.0007 ng/mL for Hg2+ (S/N = 3), a wide linear range (0.1–1000.0 ng/mL for Pb2+ and 0.001–100.0 ng/mL for Hg2+), and high accuracy (relative standard deviation, RSD≤10.0 %) and selectivity. Importantly, the SPDEs aptasensor can detect Pb2+ and Hg2+ in a sample without competition and interference, achieving accuracy comparable to that of commercial inductively coupled plasma mass spectrometry (ICP-MS). These advantages make the SPDEs aptasensor highly suitable for practical applications in environmental monitoring, food safety, and clinical diagnosis.

Enhancing Underwater Object Detection and Classification Using Advanced Imaging Techniques: A Novel Approach with Diffusion Models

Underwater object detection and classification pose significant challenges due to environmental factors such as water turbidity and variable lighting conditions. This research proposes a novel approach that integrates advanced imaging techniques with diffusion models to address these challenges effectively, aligning with Sustainable Development Goal (SDG) 14: Life Below Water. The methodology leverages the Convolutional Block Attention Module (CBAM), Modified Swin Transformer Block (MSTB), and Diffusion model to enhance the quality of underwater images, thereby improving the accuracy of object detection and classification tasks. This study utilizes the TrashCan dataset, comprising diverse underwater scenes and objects, to validate the proposed method’s efficacy. This study proposes an advanced imaging technique YOLO (you only look once) network (AIT-YOLOv7) for detecting objects in underwater images. This network uses a modified U-Net, which focuses on informative features using a convolutional block channel and spatial attentions for color correction and a modified swin transformer block for resolution enhancement. A novel diffusion model proposed using modified U-Net with ResNet understands the intricate structures in images with underwater objects, which enhances detection capabilities under challenging visual conditions. Thus, AIT-YOLOv7 net precisely detects and classifies different classes of objects present in this dataset. These improvements are crucial for applications in marine ecology research, underwater archeology, and environmental monitoring, where precise identification of marine debris, biological organisms, and submerged artifacts is essential. The proposed framework advances underwater imaging technology and supports the sustainable management of marine resources and conservation efforts. The experimental results demonstrate that state-of-the-art object detection methods, namely SSD, YOLOv3, YOLOv4, and YOLOTrashCan, achieve mean accuracies (mAP@0.5) of 57.19%, 58.12%, 59.78%, and 65.01%, respectively, whereas the proposed AIT-YOLOv7 net reaches a mean accuracy (mAP@0.5) of 81.4% on the TrashCan dataset, showing a 16.39% improvement. Due to this improvement in the accuracy and efficiency of underwater object detection, this research contributes to broader marine science and technology efforts, promoting the better understanding and management of aquatic ecosystems and helping to prevent and reduce the marine pollution, as emphasized in SDG 14.

A Highly Sensitive Chitosan-Based SERS Sensor for the Trace Detection of a Model Cationic Dye.

The rapid detection of contaminants in water resources is vital for safeguarding the environment, where the use of eco-friendly materials for water monitoring technologies has become increasingly prioritized. In this context, the role of biocomposites in the development of a SERS sensor is reported in this study. Grafted chitosan was employed as a matrix support for Ag nanoparticles (NPs) for the surface-enhanced Raman spectroscopy (SERS). Chitosan (CS) was decorated with thiol and carboxylic acid groups by incorporating S-acetyl mercaptosuccinic anhydride (SAMSA) to yield CS-SAMSA. Then, Ag NPs were immobilized onto the CS-SAMSA (Ag@CS-SAMSA) and characterized by spectral methods (IR, Raman, NIR, solid state 13C NMR with CP-MAS, XPS, and TEM). Ag@CS-SAMSA was evaluated as a substrate for SERS, where methylene blue (MB) was used as a model dye adsorbate. The Ag@CS-SAMSA sensor demonstrated a high sensitivity (with an enhancement factor ca. 108) and reusability over three cycles, with acceptable reproducibility and storage stability. The Raman imaging revealed a large SERS effect, whereas the MB detection varied from 1-100 μM. The limits of detection (LOD) and quantitation (LOQ) of the biocomposite sensor were characterized, revealing properties that rival current state-of-the-art systems. The dye adsorption profiles were studied via SERS by fitting the isotherm results with the Hill model to yield the ΔG°ads for the adsorption process. This research demonstrates a sustainable dual-function biocomposite with tailored adsorption and sensing properties suitable for potential utility in advanced water treatment technology and environmental monitoring applications.

Miniaturized photoelectrochemical sensing system for reusable detection of macromolecules and its applications for unattended environmental monitoring

Photoelectrochemical (PEC) sensors are widely employed in biochemical detection due to their accuracy and speed, but most PEC measurement systems face challenges with bulky instruments and complex operations. Current miniaturized systems based on Potentiostat and constant light are limited in accuracy and application ranges. PEC systems based on mod/demod signal processing offer high SNR and accuracy but struggles with miniaturization due to complex algorithms of Lock-in amplifier. Herein, discrete Fourier transform (DFT) algorithm instead of Lock-in algorithm was used for the photocurrent demodulation in PEC system. After functional verification, coordinate rotation digital computer (CORDIC) algorithm was used to implement DFT demodulation to further reduce resource occupancy. Afterwards, the spectral leakage was reduced by applying Hanning window, which improves the SNR and accuracy of photocurrent demodulation. Subsequently, a miniaturized, low-cost, low-power and high-accuracy PEC measurement system was obtained by integrating designed Hanning-CORDIC-DFT module, Potentiostat, light source driver and other miniaturized modules. The performances of miniaturized PEC measurement system were compared with that of the commercial PEC measurement system based on Lock-in amplifier by using the same MIP-PEC sensor, validating the feasibility and accuracy of designed miniaturized PEC system. Then, the performance of MIP-PEC sensor was investigated in detail. The results showed that MIP-PEC sensor has good sensitivity, stability, selectivity and recyclability for detecting MC-LR. The reliability of MIP-PEC sensor was further confirmed by the recovery test of MC-LR in lake water. Finally, long-term, cyclic and unattended measurements of microcystin-LR were achieved by designed miniaturized PEC system and MIP-PEC sensor under different conditions, verifying the practicality of the system for field monitoring. The designed measurement system provides a new method for constructing miniaturized PEC sensing platform, and a new solution for continuous biochemical detection in complex environments.

A multifunctional near-infrared fluorescent probe based on benzothiazole structure for fluoride-ion detection

Fluoride ions (F−) are one of the essential trace elements for the human body and are widely existed in nature. In this study, we present a novel fluorescent probe (YF-SZ-F) designed and synthesized for the specific detection of F−. The probe exhibits high sensitivity, excellent selectivity, and low cytotoxicity, making it a promising tool for biomedical applications. Imaging experiments conducted on zebrafish and Arabidopsis roots demonstrate the probe’s remarkable cellular permeability and biocompatibility, laying a solid foundation for its potential biomedical utility. Furthermore, the probe holds potential for practical applications in environmental monitoring and public health through its capability to detect fluoride ions in water samples and via mobile phone software. This multifaceted functionality underscores the broad applicability and significance of the fluorescent probe, not only in scientific research but also in real-world scenarios, contributing to the development of more convenient and precise methods for fluoride detection.

Enhanced pyrophosphate detection: Utilizing oPD-derived carbon dots and Fe3+ interactions in a paper strip biosensor

The development of portable, cost-effective, and straightforward DNA biosensors holds immense importance in various fields, including healthcare, environmental monitoring, and food safety. This study contributes to the objective by introducing an innovative approach for synthesizing carbon dots (Cdots) with high quantum yield (QY) and remarkable selectivity for Fe3+ ions. Utilizing o-phenylenediamine as a precursor, the study achieved a straightforward and environmentally friendly synthesis method, enabling the efficient detachment of metal ions from the Cdot surface upon introducing pyrophosphate (PPi). The presence of surface hydroxyl and amino groups facilitated specific Fe3+ recognition. Employing D-optimal response surface methodology, the study optimized Cdot synthesis parameters, identifying temperature and heating time as critical factors influencing QY. Statistical analysis confirmed the model's reliability, predicting maximum QY of 48.8 % with minimal deviation from experimental results. Characterization studies revealed the amorphous nature of Cdots through HR-TEM, XRD, and FTIR analysis. Furthermore, the proposed LAMP/PPi biosensing technique demonstrated higher sensitivity, specificity, and repeatability, with negligible interference from common anions and efficacy across varying pH levels. The limit of detection (LOD) of 0.079 (±0.01) μM and the detection range of 0.1 μM–2 mM underscore the biosensor's practical utility. This study highlights a promising direction for developing paper-based LAMP/PPi biosensors with potential diagnostics and environmental monitoring applications. Significantly, the biosensing technique is applicable to any DNA amplification method generating pyrophosphate (PPi) as a by-product.

Optimizing NO2 gas sensor performance: Investigating the influence of cobalt doping on WO3 recovery kinetics for enhanced gas sensing application

Gas sensors utilizing a chemiresistive metal oxide semiconductor (MOS) are extensively employed, particularly for detecting nitrogen dioxide (NO2) at moderate temperatures. However, the gas response and the recovery time are hindering the performance of the MOS. In this research, to enhance the gas response and the recovery time a systematic investigation was performed to explore the impact of cobalt (Co) doping in tungsten trioxide (WO3) and its gas sensing properties. Fascinatingly, the 3 mM% Co-doped WO3 sensor exhibits a remarkable gas sensing response of 20776 % at 10 ppm NO2, showcasing a seven-fold enhancement compared to the pristine WO3 sample at 200 ℃. The findings demonstrated that the sensor exhibited an outstanding repeatability, selectivity and long-term stability of 95 % over 8 weeks. Moreover, the sensor possessed a fast response and recovery time 15 s/23 s as compared to the pristine sensor 26 s/154 s. The exceptional gas-sensing capabilities can be ascribed to the existence of defects (oxygen vacancy) within the structure. These defects effectively boost the surface reactivity of WO3 nanoplates, thereby augmenting their sensitivity and enabling a broad-range sensing performance. As a result, this research demonstrates considerable promise for utilizing environmental NO2 monitoring applications.

Innovations in ion-selective optodes: a comprehensive exploration of modern designs and nanomaterial integration.

In recent years, ion-selective optodes (ISOs) have remarkably progressed, driven by innovative modern designs and nanomaterial integration. This review explored the development of modern ISO by describing state-of-the-art strategies to improve their sensitivity, selectivity, and real-time monitoring capacity. The review reported the traditional membrane based-optodes, and investigated the latest research, current design principles, and the use of essential components, such as ionophores, indicator dyes, polymer membranes, and nanomaterials, in ISO fabrication. Special attention was given to nanomaterials (e.g., quantum dots, polymer dots, nanospheres, nanorods and nanocapsules) and particularly on how rare earth elements can further enhance their potential. It also described innovative ISO designs, including wearable optodes, smartphone-based optodes, and disposable paper-based optodes. As the pursuit of highly sensitive, selective, and adaptable ion sensing devices continues, this summary of the current knowledge sets the stage for upcoming innovations and applications in different domains (pharmaceutical formulations, medical diagnosis, environmental monitoring, and industrial applications).