Reusable Sensor Research Articles

A reusable and sensitive electrochemical sensor for determination of idarubicin in environmental and biological samples based on NiFe2O4 nanospheres anchored N-doped graphene quantum dots composite; an electrochemical and molecular docking investigation

An ultrasensitive and selective voltammetric sensor with ultra-trace level detection limit is introduced for idarubicin (IDA) determination in real samples. The as-synthesized nanocomposite was characterized by several techniques, including Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, Energy-dispersive X-ray spectroscopy (EDX), and Field emission scanning electron microscopy (FE-SEM). The electrocatalytic performance of the developed electrode was observed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and chronoamperometry. The limit of detection (LOD) of the developed sensor for idarubicin is 1.0 nM, and the response is found to be in the dynamic concentration range of 0.01–1.9 μmol/L in a Britton–Robinson buffer (B-R, pH = 6.0). Moreover, the fabricated electrode illustrated high selectivity with good repeatability and reproducibility for diagnosing idarubicin as an anthracycline antileukemic drug. Furthermore, to evaluate the validity of the recommended method, three real samples, including human plasma, urine, and water samples, were analyzed with satisfactory recovery and compared with high-performance liquid chromatography (HPLC). The minor groove-binding mode of interaction was also supported by docking simulation studies, emphasizing that IDA can bind to ds-DNA preferably and confirmed experimental results. The reduced assay time and the possibility of measuring a single sample with another anticancer drug without any interference are significant advantages compared to the HPLC. The developed and validated sensor could be a valuable point-of-care diagnostic tool for IDA quantification in patients.

Bandgap engineering of strained S-terminated MXene and its promising application as NOx gas sensor

Very recently, Kamysbayev et al.’s study (Science, 2020, 369, 979) reported the successful synthesis of S-terminated MXenes, while the metallic properties of these materials suppress their further applications. In the present study, by taking M2CS2 (M = Ti, Hf or Zr) as the examples, our theoretical results revealed that the M2CS2 exhibits the high selectivity and poor sensitivity towards NOx gases. To solve this issue, the electronic property of M2CS2 was considered to modulate by applying strains. It is found that the band gap of Hf2CS2 is opened at 5% biaxial strain under the GGA-PBE functional, while the structures of Ti2CS2 and Zr2CS2 become disordered during the modulation processes. Interestingly, the Hf2CS2 at 5% biaxial strain changes from semiconductor into conductor after the adsorption of NOx, and the sensitivity of Hf2CS2 towards NO and NO2 increases from 15% and 21% (without strain) to 106% and 329% (at 5% strain), respectively. Together with the moderate adsorption energies (−0.33 to −0.17 eV), we proposed that the Hf2CS2 is a promising reusable NOx gas sensor with both high selectivity and sensitivity. More importantly, our results provided an effective strategy to modulate the electronic properties of S-terminated MXenes, which will further extend their applications.

A zinc oxide nanorods/molybdenum disulfide nanosheets hybrid as a sensitive and reusable electrochemical sensor for determination of anti-retroviral agent indinavir

This work aims to develop an electrochemical sensor for the reusable and selective detection of trace levels of indinavir (IDV) as an anti-retroviral drug by using zinc oxide nano-rods/molybdenum disulfide nanosheets on a screen-printed electrode (ZnO NRs/MoS2 NSs/SPE). Quantitative IDV detection was achieved using differential pulse voltammetry (DPV). The assay specificity was illustrated using interfering species and exhibited high specificity toward the IDV. The developed displayed a wide dynamic range, from 0.01 to 0.66 and 0.66–7.88 μM in Britton–Robinson (B-R) buffer, with a 0.007 μM limit of detection. The fabricated ZnO NRs/MoS2 NSs/SPE electrode exhibited high sensitivity, stability, good reproducibility, and repeatability towards the sensing of IDV. It turned out that the hybrid electrochemical sensor's sensing performance was remarkably improved due to the synergistic effect between MoS2 NSs and ZnO NRs, where the former affords a large active surface area and quick electron transfer. The reported sensor provides a new alternative for electrochemical detection of IDV and could expand the applications of metal nanoparticles in emerging technologies for monitoring drugs in real samples.

Towards the development of reagent-free and reusable electrochemical aptamer-based cortisol sensor

Continuous monitoring of stress through detecting specific biochemical markers such as cortisol plays a crucial role in the early detection of various diseases. Electrochemical aptamer sensor involving binding induced conformational change allows the continuous measurement of biomarkers. A reagent-less aptamer-based biosensing platform that allows a continuous and real-time cortisol measurement is developed in this context. The aptamer is conjugated with methylene blue, which acts as a redox reporter to probe the cortisol binding quantitatively on the sensor surface. The cortisol specific aptamers were chemically modified with amine and thiol functional groups to facilitate redox reporter conjugation and attachment of aptamer to a gold electrode, respectively. The sensor achieves a clinically meaningful cortisol concentration ranging from 0.05 ng/mL to 100 ng/mL and provides good selectivity when challenged with structurally similar targets. The reagent-less measurement capability was also demonstrated using an undiluted human serum. The newly developed cortisol sensor can enable the systemic cortisol measurement for providing insights into cortisol related clinical conditions and medical treatments.

Reusable dual-functional SERS sensor based on gold nanoflowers-modified red phosphorus nanoplates for ultrasensitive immunoassay and degradation of CA19-9

It is tremendously desirable for the timely and effective detection of cancer to facilitate the ultra-highly sensitive monitoring of tumor marker in clinical serum sample. In this study, an electromagnetic and chemical synergistically enabled recyclable immunoassay based on surface-enhanced Raman scattering (SERS) was proposed by realizing the anisotropic growth of sea-urchin-like gold nanoflowers (Au NFs) on two-dimensional red phosphorus (RP) nanoplates. Besides the achieved enhancement factor as high as 2.24 × 106, it was found that the photocatalytic and SERS activities were kept at a high level for the hybrid substrate of RP/Au NFs throughout 7 cycles of immunoassay. In combination with a non-metallic immunoprobe, the limit of detection was drove to 7.41 × 10−5 IU·mL−1 for cancer antigen 19–9. The comparative experiments of nonspecific monitoring verified the promising selectivity of this strategy. Considering the intriguing features of high sensitivity, recyclability, and specificity, the proposed multifunctional RP/Au NFs exhibited its superior role in the early detection of cancer and can be adapted for point-of-care diagnosis.

Adsorption Behavior of Environmental Gas Molecules on Pristine and Defective MoSi2N4: Possible Application as Highly Sensitive and Reusable Gas Sensors.

Inspired by the recent practical application of two-dimensional (2D) nanomaterials as gas sensors, catalysts, and materials for waste gas disposal, herein, the adsorption behaviors of environmental gas molecules, including NO, CO, O2, CO2, NO2, H2O, H2S, and NH3, on the 2D pristine and defective MoSi2N4 (MSN) monolayers were systematically investigated using spin-polarized density functional theory (DFT) calculations. Our results reveal that all the gas molecules are physically adsorbed on the MSN surface with small charge transfer, but the electronic structures of NO, NO2, and O2 are obviously modified due to the in-gap states. The introduction of N vacancy on the MSN surface enhances the interaction between gas molecules and the substrate, especially for NO2 and O2. Interestingly, the adsorption type of NO and CO evolves from physisorption to chemisorption, which may be utilized in NO and CO catalytic reaction. Furthermore, the moderate adsorption strength and obvious changes in electronic properties of H2O and H2S on the defective MSN make them have promising prospects in highly sensitive and reusable gas sensors. This work offers several promising gas sensors based on the MSN monolayer and also provides a theoretical reference of other related 2D materials in the field of gas sensors, catalysts, and toxic gas disposal.

A Packaged and Reusable Hydrogel Strain Sensor with Conformal Adhesion to Skin for Human Motions Monitoring (Adv. Mater. Interfaces 6/2022)

Hydrogel Strain Sensor In article number 2101786, Meijin Zhao, Lingxiao Xu, Lei Shi, and co-workers use photopolymerizable hydrogel as external packaging layer for hydrogel conducting wires bearing linear sensing property. The inhibition of water evaporation by packaging strategy endows the hydrogel sensor with enhanced lifespan. Besides, the sensor exhibits good reusability benefiting from the swelling property of external hydrogel film.

A reusable and self-recoverable vitrified film of an anisometric europium(III) β-diketonate complex with UV light-responsive Eu3+ emission

We report on photophysical properties of a 20 µm thick vitrified film (fabricated from a powder of an anisometric europium(III) β-diketonate complex through a melt-processing technique and sandwiched between two quartz plates), which are highly unusual for known film-type materials based on non-mesogenic lanthanide(III) β-diketonate complexes. The film excited by light in the wavelength range of 280–425 nm exhibits a bright orange-red narrow-band emission of Eu3+ ions (due to efficient ligand-to-metal energy transfer) with 530 µs decay time. The prolonged irradiation of the film with a 337 nm nitrogen laser decreases the luminescence brightness of the Eu3+ ions without decomposition of the anisometric complexes. Then the luminescence gradually recovers during storage of the film in the dark for at least 19 h at room temperature. Interestingly, the film is capable of repeatedly reversible changing the luminescence brightness upon alternating UV laser irradiation and dark storage. The observed self-recovery phenomenon can be presented as an elastic photodeformation of local structures of the film with following changes in the Eu3+ ions emission parameters. We believe that the found film properties are promising for the design and development of novel reusable luminescent sensors or dosimeters of UV radiation.

A sensitive electrochemical sensor based on wrinkled mesoporous carbon nanomaterials for rapid and reliable assay of 17β-estradiol

In this study, we establish a sensitive and reusable electrochemical sensor for assay of 17β-estradiol (17β-E2) based on wrinkled mesoporous carbon (wMC) nanomaterials. wMC was synthesized by using the wrinkled silicon nanoparticle (wSiO2NP) as supporting and sacrificial hard template, which formed a hollow nanocage-like structure. Such a carbon-based composite structure endows rich accessible active sites, large specific surface area and high electrocatalytic activity. High performance electrochemical sensor based on the wMC modified electrodes has been achieved for various assays, presenting excellent reusability by a simple regeneration treatment for removal of fouling (phenolic compounds) in tetrabutyl ammonium hexafluorate (TAH)-acetone solution. For 17β-E2 assay, the linear response in the ranges of 0.05–10.0 μM and 10.0–80.0 μM have been achieved with the detection limit of 8.3 nM (S/N = 3). This sensor has also been successfully applied for the determination of 17β-E2 in the milk and real water samples, exhibiting comparable results measured using a high-performance liquid chromatography. This sensor presents high sensitivity, selectivity, reproducibility, and especially the validated recoverability, showing high potential for endocrine disrupting chemical assay.

Analysis of photostimulable phosphor image plate artifacts and their prevalence.

BACKGROUND Digital radiography has recently been used in dentistry as a substitute for conventional film radiography worldwide. Digital imaging has many advantages and provides new possibilities for recording and interpreting radiographic data. This system uses different types of digital receptors.AIMTo detect the frequency, type, and reasons behind the appearance of intraoral image artifacts acquired by photostimulable phosphor plates (PSP).METHODSThis retrospective descriptive study was conducted in the oral and maxillofacial radiology unit of the dental clinics of the College of Dentistry, Princess Nourah University (PNU). All intraoral digital radiographs were acquired using (Gendex Expert DC., United States) an intraoral X-ray machine with 7 -mA, 65-kVP using a PSP system (Soredex DIGORA Optime imaging plate) and laser scanners (Soredex DIGORA Optime), which can house all sizes of reusable intraoral PSP sensor plates with image acquisition software (MIPACS Dental Enterprise viewer 3.2.2). A total of 50000 intraoral radiographs were retrieved from the clinical database from April 2018 to April 2020 to evaluate the reason, type, and solutions to these image artifacts.RESULTSOverall, 50000 intraoral digital radiographs were acquired in a two-year-period; that is, from April 2018 to April 2020. Of these, 3550 (7.1%) retakes were performed due to the presence of image artifacts. Periapical radiographs were the most common image type of intraoral retakes (80.8%). Imaging artifacts were divided into three categories: operator, plate and scanning errors. Out of 3550 retakes, 5%, 1.37%, and 0.73% were related to operator, plate, and scanning errors, respectively. The cone cut was the most common operator error (988 images), Bite marks were the most common plate error (276 images), and delayed scanning artifacts were the most common scanning errors (145 images). The calculated kappa value for interobserver reliability was 0.99, indicating almost perfect interobserver agreement. CONCLUSIONOur study discussed intraoral image artifacts that were characteristic of PSP, where the most common artifacts were bitemarks, image size reduction, scratches, and delayed scanning.

Density Functional Theory Study of B, N, and Si Doped Penta-Graphene as the Potential Gas Sensors for NH3 Detection.

Designing a high-performance gas sensor to efficiently detect the hazardous NH3 molecule is beneficial to air monitoring and pollution control. In this work, the first-principles calculations were employed to investigate the adsorption structures, electronic characteristics, and gas sensing properties of the pristine and B-, N-, P-, Al-, and Si-doped penta-graphene (PG) toward the NH3, H2S, and SO2 molecules. The results indicate that the pristine PG is insensitive to those toxic gases due to the weak adsorption strength and long adsorption distance. Nevertheless, the doping of B, N, Al, and Si (B and Al) results in the transition of NH3 (H2S and SO2) adsorption from physisorption to chemisorption, which is primarily ascribed to the large charge transfer and strong orbital hybridizations between gas molecules and doping atoms. In addition, NH3 adsorption leads to the remarkable variation of electrical conductivity for the B-, N-, and Si-doped PG, and the adsorption strength of NH3 on the B-, N-, and Si-doped PG is larger than that of H2S and SO2. Moreover, the chemically adsorbed NH3 molecule on the N-, B-, and Si-doped PG can be effectively desorbed by injecting electrons into the systems. Those results shed light on the potential application of PG-based nanosheets as reusable gas sensors for NH3 detection.

Deep and dip: Immobilization on paper substrate using Deep Eutectic solvent to fabricate reusable dip immersion colorimetric sensor arrays

A novel method for immobilization of hydrophilic indicators on the surface of the paper-based strips, for using in aqueous solution, has been developed. For this aim, a hydrophobic deep eutectic solvent (DES) was used to immobilize indicators on a paper without hydrophobic barriers. The proposed user-friendly colorimetric strip presented homogeneous color, reversibility, and significant leaching stability over months. For designing the pH strip as a model analyte, two ethanolic pH indicators were dissolved in DES and spotted on a Benchkote paper. The fabricated strip coupled with multivariate analysis exhibited excellent performance in semi-quantitative and quantitative analysis of pH value in the range of 2.0 – 12.0 with 0.5 unit increments based on their color variations. The principal component analysis of different buffer solutions in whole pH range demonstrates 100% classification accuracy. Also, partial least square (PLS) regression method was used to estimate the pH values of different samples through image analysis. A root mean square error for calibration and prediction of the pH value in the whole range of universal buffer was obtained as 0.22 and 0.21, respectively. The applicability of the prepared pH strip confirmed by fast and easy detection of pH in seven different real matrices, including food (dairy and juice products), biological (bacteria and cell culture media), and tap water samples.

Reusable and pH-Stable Luminescent Sensors for Highly Selective Detection of Phosphate.

Phosphate sensors have been actively studied owing to their importance in water environment monitoring because phosphate is one of the nutrients that result in algal blooms. As with other nutrients, seamless monitoring of phosphate is important for understanding and evaluating eutrophication. However, field-deployable phosphate sensors have not been well developed yet due to the chemical characteristics of phosphate. In this paper, we report on a luminescent coordination polymer particle (CPP) that can respond selectively and sensitively to a phosphate ion against other ions in an aquatic ecosystem. The CPPs with an average size of 88.1 ± 12.2 nm are embedded into membranes for reusable purpose. Due to the specific binding of phosphates to europium ions, the luminescence quenching behavior of CPPs embedded into membranes shows a linear relationship with phosphate concentrations (3–500 μM) and detection limit of 1.52 μM. Consistent luminescence signals were also observed during repeated measurements in the pH range of 3–10. Moreover, the practical application was confirmed by sensing phosphate in actual environmental samples such as tap water and lake water.

Highly sensitive, selective, and reusable nanofibrous membrane-based carbon polymer dots sensors for detection of Cr(VI) in water

Core-shell structured fluorescent carbon polymer dots (CPDs) were covalently incorporated onto poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers to fabricate novel nanofibrous membrane sensors to detect trace amount of heavy metal ions in drinking water systems. The membrane sensor was assembled in a syringe filter cell as a sensor unit together with a volumetric syringe, and fluorescent color changes of the sensors responding to concentrations of Cr(VI) can be identified by naked eyes. The sensor system possesses features of instant detection, low cost, environment-friendliness, and high sensitivity to quantitative measure Cr(VI) in a concentration range of 1–50 ppb, which is much lower than federal permissible limit of Cr(VI) in drinking water. Moreover, the used sensor could be refreshed and reused for many times without obvious fluorescence loss and nanofibrous membrane damage by simply exposing to a 20 μM Vitamin C (VC) solution. The fluorescent color changes of the sensors could be read by an App on a smartphone, which is facile, convenient and suitable for more accurate household operation, showing great prospect for instant on-site detection of Cr(VI) in drinking water.

CF3 H-bonding locked aromatic stacking of picric acid with mechanofluorochromic fluorophores: highly selective reusable sensor and rewritable fluorescence platform

Integrating the CF3 functional group into a mechanofluorochromic organic molecule facilitated the fabrication of a highly selective, reusable fluorescent sensor for PA in aqueous medium and rewritable fluorescence platforms.

Highly sensitive metal ion sensing by graphene oxide functionalized micro-tapered long-period fiber grating.

An accurate as well as highly sensitive label-free chemical sensing platform for the detection of various metal ions was demonstrated. The chemical sensor was derived from the micro-tapered long-period fiber grating (MLPG) by depositing graphene oxide (GO) by chemical-bonding and optical-tweezer effects. The enhancement in refractive index (RI) sensitivity as well as reusability was obtained by evaluating the deposition thickness in the range of approximately 97.7 to 158.9 nm. Based on the analysis of adsorption principles, the enhanced RI sensitivity leads to a limit of detection as low as 3.2 ppb. The highest sensitivities for the cases studied using sodium and manganese ions in a wide concentration range of 1 ppb to 1 × 106 ppb are respectively 2.2 × 10-3 dB per ppb and 3.2 × 10-3 dB per ppb. Mixture samples were also studied to evaluate the properties of sensing the doped ions. This demonstration of GO modified MLPG is bound to find potential applications that require sensing of mixed samples and illustrates significant importance in developing cost-effective, label-free, reusable, and real-time chemical sensors.

Highly Stable and Reusable 3d Graphene-Quinizarin Potentiometric Ph Sensor

Highly Stable and Reusable 3d Graphene-Quinizarin Potentiometric Ph Sensor

Molecular engineering of ruthenium(ii) complexes with (3-polyamino)phenanthroline ligands for developing reusable optical sensors for Cu(ii) ions

A reusable sensor based on a phosphonate-substituted Ru(ii) complex allows for selective detection as low as 10−13 M of Cu2+ ions in aqueous solutions.

Eco‐Friendly Colorimetric Nanofiber Design: Halochromic Sensors with Tunable pH‐Sensing Regime Based on 2‐Ethyl‐2‐Oxazoline and 2‐n‐Butyl‐2‐Oxazoline Statistical Copolymers Functionalized with Alizarin Yellow R (Adv. Funct. Mater. 1/2022)

Eco-Friendly Electrospinning In article number 2106859, Richard Hoogenboom, Karen De Clerck, and co-workers show that functionalization and electrospinning of 2-ethyl-2-oxazoline and 2-n-butyl-2-oxazoline statistical copolymers with alizarin yellow R (AYR) analogues leads to eco-friendly designed halochromic nanofibrous sensors of which responsivity, stability, sensitivity, and pH-response can be tuned by varying support copolymer and AYR-modified polymer chain length, resulting in user-friendly reusable sensors for sub-ppm detection of biogenic amines applicable in breath analysis or food packaging.

A high-stable and sensitive colorimetric nanofiber sensor based on PCL incorporating anthocyanins for shrimp freshness

A novel bilayer colorimetric film incorporating polycaprolactone (PCL) with clitoria ternatea Linn anthocyanin (CA) via electrospinning was designed. The PCL nanofibers layer acted as a protective layer against harsh environments as the strong hydrophobic with the WCA (water contact angle) values of 101.79°. The PCL-CA layer worked as an indicator for its significant color changes for pH. The sensitivity test verified the ammonia cycler reversibility of the nanofibers is promising for re-use packaging. And the PCL/PCL-CA film was characterized as suitable WVP (water vapour permeability), and the lower velocity of water penetrating. Moreover, higher elongation at break (240.431%), and color stability were achieved. Besides, the film exhibited the color change from pale-blue to yellow-green response as an indication of shrimp spoilage (21 h). These results suggested the potential application of the PCL/PCL-CA film for a reusable freshness sensor tool in food packaging.