Sea urchin nanostructured nickel cobaltite modified carbon cloth integrated wearable patches for the on-site detection of the immunosuppressant drug mycophenolate mofetil.

Mycophenolate mofetil (MpM) is a medication used to prevent the rejection of transplanted organs, particularly in kidney, heart, and liver transplant surgeries. It is extremely important to be conscious that MpM can raise the risk of severe infections and some cancers if it exceeds the recommended dose while lower doses will result in organ rejections. So, it is essential to monitor the dosage of MpM in real time in the micromolar range. In this work, we have synthesized 3-aminopropyltriethoxysilane (APTES) functionalized nickel cobaltite (NiCo2O4) and this amino functionalization was chosen to enhance the stability and electrochemical activity of NiCo2O4. The enhanced activity of NiCo2O4 was used for developing an electrochemical sensor for the detection of MpM. APTES functionalized NiCo2O4 was coated on carbon cloth and used as the working electrode. Surface functionalization with APTES on NiCo2O4 was aimed at augmenting the adsorption/interaction of MpM due to its binding properties. The developed sensor showed a very low detection limit of 1.23 nM with linear ranges of 10-100 nM and 1-100 µM and its practical applicability was examined using artificial samples of blood serum and cerebrospinal fluid, validating its potential application in real-life scenarios.

Cross-linked laminar graphene oxide membranes for wastewater treatment and desalination: A review.

Two-dimensional (2D) lamellar graphene oxide (GO) membranes are emerging as attractive materials for molecular separation in water treatment because of their single atomic thickness, excellent hydrophilicity, large specific surface areas, and controllable properties. To yet, commercialization of GO laminar membranes has been hindered by their propensity to swell in hydrated conditions. Thus, chemical crosslinking of GO sheets with the polymer matrix is used to improve GO membrane hydration stability. This review focuses on pertinent themes such as how chemical crosslinking improves the hydration stability, separation performance, and antifouling properties of GO membranes.

Ultrasensitive colorimetric detection of NF-κB protein at picomolar levels using target-induced passivation of nanoparticles.

We developed a highly sensitive and selective sensor based on the nanoprobe conjugates of catalytic nanoparticles and double-stranded DNA (dsDNA) for the colorimetric detection of NF-κB protein. The sensing mechanism takes advantage of the catalytic activity of nanoparticle surfaces and the specific binding of NF-κB to a dsDNA sequence. In the presence of NF-κB, the highly selective interactions between dsDNA and NF-κB lead to the passivation of the catalytic nanoparticle surfaces, impeding the sodium borohydride-mediated reduction rate of 4-nitrophenol. The correlation between the NF-κB concentration and the visualized reduction rate of 4-nitrophenol from yellow to colorless clearly demonstrates the highly quantitative nature of the sensor. Importantly, this sensor can conclusively detect concentrations as low as 6.39 pM of NF-κB, which to best of our knowledge is the lowest limit of detection for a colorimetric NF-κB detection system. The excellent sensitivity of this sensor relies on the high binding constant of NF-κB to dsDNA and the catalytic activity of nanoparticle surfaces for the signal amplification. This sensor allows visual detection without the need for any spectrometric instrumentation. We also determined the various parameters such as the pH, temperature, incubation time, and salt concentration for optimal NF-κB-dsDNA interactions. Finally, we demonstrated the performance of the sensor with simulated sample analysis. Graphical abstract A highly sensitive and selective colorimetric detection of protein NF-κB using the nanoprobeconjugates of catalytic gold nanoparticles and double-stranded DNA (dsDNA) has been developed.

A highly sensitive DNA sensor for attomolar detection of the BRCA1 gene: signal amplification with gold nanoparticle clusters.

Single stranded DNA fragments were conjugated onto gold nanoparticles leading to the formation of gold nanoparticle clusters upon hybridization with complementary strands. These clusters were successfully implemented for signal amplification in an electrochemical DNA sensor based on a graphene substrate. The sensor exhibited excellent sensitivity and selectivity with a detection limit of 50 attomolar target DNA.

Graphene quantum dots for biosensing and bioimaging.

Graphene Quantum Dots (GQDs) are low dimensional carbon based materials with interesting physical, chemical and biological properties that enable their applications in numerous fields. GQDs possess unique electronic structures that impart special functional attributes such as tunable optical/electrical properties in addition to heteroatom-doping and more importantly a propensity for surface functionalization for applications in biosensing and bioimaging. Herein, we review the recent advancements in the top-down and bottom-up approaches for the synthesis of GQDs. Following this, we present a detailed review of the various surface properties of GQDs and their applications in bioimaging and biosensing. GQDs have been used for fluorescence imaging for visualizing tumours and monitoring the therapeutic responses in addition to magnetic resonance imaging applications. Similarly, the photoluminescence based biosensing applications of GQDs for the detection of hydrogen peroxide, micro RNA, DNA, horse radish peroxidase, heavy metal ions, negatively charged ions, cardiac troponin, etc. are discussed in this review. Finally, we conclude the review with a discussion on future prospects.

Ecotoxicity and environmental safety assessment of two-dimensional niobium carbides (MXenes).

Two-dimensional (2D) MXenes have gained great interest in water treatment, biomedical, and environmental applications. The antimicrobial activity and cell toxicity of several MXenes including Nb4C3Tx and Nb2CTx have already been explored. However, potential side effects related to Nb-MXene toxicity, especially on aquatic pneuma, have rarely been studied. Using zebrafish embryos, we investigated and compared the potential acute toxicity between two forms of Nb-MXene: the multilayer (ML-Nb4C3Tx, ML-Nb2CTx) and the delaminated (DL-Nb2CTx, and DL-Nb4C3Tx) Nb-MXene. The LC50 of ML-Nb4C3Tx, ML-Nb2CTx, DL-Nb2CTx, and DL-Nb4C3Tx were estimated to be 220, 215, 225, and 128 mg/L, respectively. Although DL-Nb2CTx, and DL-Nb4C3Tx derivatives have similar sizes, DL-Nb4C3Tx not only shows the higher mortality (LC50 = 128 mg/L Vs 225 mg/L), but also the highest teratogenic effect (NOEC = 100 mg/L Vs 200 mg/L). LDH release assay suggested more cell membrane damage and a higher superoxide anion production in DL-Nb4C3Tx than DL-Nb2CTx,. Interestingly, both DL-Nb-MXene nanosheets showed insignificant cardiac, hepatic, or behavioral toxic effects compared to the negative control. Embryos treated with the NOEC of DL-Nb2CTx presented hyperlocomotion, while embryos treated with the NOEC of DL-Nb4C3Tx presented hyperlocomotion, suggesting developmental neurotoxic effect and muscle impairment induced by both DL-Nb-MXene. According to the Fish and Wildlife Service (FSW) Acute Toxicity Rating Scale, all tested Nb-MXene nanosheets were classified as "Practically not toxic". However, DL-Nb4C3Tx should be treated with caution as it might cause a neurotoxic effect on fauna when it ends up in wastewater in high concentrations.

Ru-W modified graphitic carbon nitride by a monomer complexation synthesis approach from a tailored polyoxometalate: towards electrochemical detection of hydrogen peroxide released by cells.

Detection of hydrogen peroxide (H2O2) from cell cultures is important for monitoring different diseases. Here, g-C3N4 (gCN) was incorporated into well-defined clusters of RuW (RuW-gCN) through monomer complexation of Ru-substituted phosphotungstate and melamine for electrochemical detection of H2O2. RuW-gCN exhibited enhanced electrochemical sensing properties in comparison to its constituents due to the synergic effects between RuW and gCN. The characterization of RuW-gCN revealed successful complexation to form the composite in addition to the presence of a layered structure of gCN. The electrochemical sensor made of RuW-gCN was able to detect H2O2 with a detection limit of 46 nM in the linear ranges from 100 nM to 50 µM and from 50 µM to 1 mM. The developed sensor was employed for the selective detection of H2O2 in the presence of analytes like ascorbic acid (AA), dopamine, and glucose in addition to being stable even after a week of storage at room temperature. It has also been verified for real sample application by detecting H2O2 produced by cancer cells as a result of an AA trigger.

Improved defluoridation and energy production using dimethyl sulfoxide modified carbon cloth as bioanode in microbial desalination cell.

In the present study, carbon cloth (CC) was functionalized using dimethyl sulfoxide (DMSO) and employed as an excellent bioanode for improving defluoridation efficiency, wastewater treatment, and power output from a microbial desalination cell (MDC). The Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis of DMSO modified carbon cloth (CCDMSO) confirmed the functionalization of CCDMSO, and the water drop contact angle of 0° ensured its superior hydrophilicity. The presence of -COOH (carboxyl), S[bond, double bond]O (sulfoxide) and O-C[bond, double bond]O (carbonyl) functional groups on CCDMSO aids in enhancing the performance of the MDC. Besides, cyclic voltametric and electrochemical impedance analysis revealed that CCDMSO had an excellent electrochemical performance with low charge transfer resistance. Replacing CC with CCDMSO as anode in MDC, the time required for 3,10 and 20 mg/L of initial fluoride (F-) concentrations in the middle chamber was reduced from 24 ± 0.75 to 17 ± 0.37, 72 ± 1 to 48 ± 0.70, and 120 ± 0.5 to 96 ± 0.53 h, respectively to meet the prescribed standards (1.5 mg/L). Furthermore, using CCDMSO, the anode chamber of MDC exhibited a maximum of 83% substrate degradation, and simultaneously, the power output is increased by 2-2.8 times. CCDMSO improved the power production from 0.009 ± 0.003, 1.394 ± 0.06 and 1.423 ± 0.15 mW/m2 to 0.020 ± 0.07, 2.748 ± 0.22 and 3.245 ± 0.16 mW/m2, respectively, for initial F- concentrations of 3,10, and 20 mg/L. Modifying CC with DMSO thus proved to be an efficient and simple methodology for enhancing the overall performance of MDC.

Acoustic platforms meet MXenes - a new paradigm shift in the palette of biomedical applications.

The wide applicability of acoustics in the life of mankind spread over health, energy, environment, and others. These acoustic technologies rely on the properties of the materials with which they are made of. However, traditional devices have failed to develop into low-cost, portable devices and need to overcome issues like sensitivity, tunability, and applicability in biological in vivo studies. Nanomaterials, especially 2D materials, have already been proven to produce high optical contrast in photoacoustic applications. One such wonder kid in the materials family is MXenes, which are transition metal carbides, that are nowadays flourishing in the materials world. Recently, it has been demonstrated that MXene nanosheets and quantum dots can be synthesized by acoustic excitations. In addition, MXene can be used as a mechanical sensing material for building piezoresistive sensors to realize sound detection as it produces a sensitive response to pressure and vibration. It has also been demonstrated that MXene nanosheets show high photothermal conversion capability, which can be utilized in cancer treatment and photoacoustic imaging (PAI). In this review, we have rendered the role of acoustics in the palette of MXene, including acoustic synthetic strategies of MXenes, applications such as acoustic sensors, PAI, thermoacoustic devices, sonodynamic therapy, artificial ear drum, and others. The review also discusses the challenges and future prospects of using MXene in acoustic platforms in detail. To the best of our knowledge, this is the first review combining acoustic science in MXene research.

A review on advances in the development of electrochemical sensors for the detection of anesthetic drugs.

Surgeries are a crucial medical intervention that has saved countless lives from time immemorial. To reduce pain during surgeries patients are administered with anesthetic drugs, which cause loss of sensation and thus reduce the pain involved. However, anesthetists control the effects of the drug by depending on pharmacokinetic calculations, which may vary from patient to patient, thus leading to a reduction in the quality of anesthetic care and adverse effects. To avoid these adverse effects, it is highly necessary to implement a real time monitoring of plasma drug concentration, which will adjust the drug infusion and maintain the levels of drug within therapeutic levels. To implement such a system, it is highly essential to analyze current advances in electrochemical sensor systems for different types of anesthetic drugs like opioids, intravenous anesthetics, and neuromuscular blockers. This review focuses on the present strategy of electrochemical sensors implemented for the detection of anesthetic drugs and it helps towards developing a real time drug dispensing system with respect to the plasma concentration of the drug. This analysis will contribute towards establishing highly effective real time drug dispensing systems like the total intravenous anesthesia technique and patient-controlled analgesia. Such systems will lead to better usage of anesthetic drugs and improve the quality of anesthetic care thus making surgeries safer and more painless.

Enhanced water flux and bacterial resistance in cellulose acetate membranes with quaternary ammoniumpropylated polysilsesquioxane.

An enhanced water flux and anti-fouling nanocomposite ultrafiltration membrane based on quaternary ammoniumpropylated polysilsesquioxane (QAPS)/cellulose acetate (QAPS@CA) was fabricated by in situ sol-gel processing via phase inversion followed by quaternization with methyl iodide (CH3I). Membrane characterizations were performed based on the contact angle, FTIR, SEM, and TGA properties. Membrane separation performance was assessed in terms of pure water flux, rejection, and fouling resistance. The 7%QAPS@CA nanocomposite membrane showed an increased wettability (46.6° water contact angle), water uptake (113%) and a high pure water permeability of ∼370 L m-2 h-1 bar-1. Furthermore, the 7%QAPS@CA nanocomposite membrane exhibited excellent bactericidal properties (∼97.5% growth inhibition) against Escherichia coli (E. coli) compared to the bare CA membrane (0% growth inhibition). The 7%QAPS@CA nanocomposite membrane can be recommended for water treatment and biomedical applications.

Large interlayer spacing Nb4C3T x (MXene) promotes the ultrasensitive electrochemical detection of Pb2+ on glassy carbon electrodes.

A Nb4C3T x (MXene)-modified glassy carbon electrode was used for the electrochemical detection of Pb2+ ions in aqueous media. The sensing platform was evaluated by anodic stripping analysis after optimizing the influencing factors such as pH, deposition potential, and time. The large interlayer spacing, high c lattice parameter and higher conductivity of Nb4C3T x compared to other MXenes enhance the electrochemical detection of Pb2+. The developed sensor can reach a detection limit of 12 nM at a potential ∼-0.6 V. Additionally, the developed sensor showed promising selectivity in the presence of Cu2+ and Cd2+, and stability for at least 5 cycles of continuous measurements with good repeatability. This work demonstrates the potential applications of Nb4C3T x towards the development of effective electrochemical sensors.

Carbon nanostructures as immobilization platform for DNA: A review on current progress in electrochemical DNA sensors.

Development of a sensitive, specific and cost-effective DNA detection method is motivated by increasing demand for the early stage diagnosis of genetic diseases. Recent developments in the design and fabrication of efficient sensor platforms based on nanostructures make the highly sensitive sensors which could indicate very low detection limit to the level of few molecules, a realistic possibility. Electrochemical detection methods are widely used in DNA diagnostics as it provide simple, accurate and inexpensive platform for DNA detection. In addition, the electrochemical DNA sensors provide direct electronic signal without the use of expensive signal transduction equipment and facilitates the immobilization of single stranded DNA (ssDNA) probe sequences on a wide variety of electrode substrates. It has been found that a range of nanomaterials such as metal nanoparticles (MNPs), carbon based nanomaterials, quantum dots (QDs), magnetic nanoparticles and polymeric NPs have been introduced in the sensor design to enhance the sensing performance of electrochemical DNA sensor. In this review, we discuss recent progress in the design and fabrication of efficient electrochemical genosensors based on carbon nanostructures such as carbon nanotubes, graphene, graphene oxide and nanodiamonds.

Reduced graphene oxide-yttria nanocomposite modified electrode for enhancing the sensitivity of electrochemical genosensor.

Reduced graphene oxide-yttria nanocomposite (rGO:Y) is applied as electrochemical genosensor platform for ultrahigh sensitive detection of breast cancer 1 (BRCA1) gene for the first time. The sensor is based on the sandwich assay in which gold nanoparticle cluster labeled reporter DNA hybridize to the target DNA. Glassy carbon electrode modified with rGO-yttria serves as the immobilization platform for capture probe DNA. The sensor exhibited a fine capability of sensing BRCA1 gene with linear range of 10attomolar (aM) to 1nanomolar (nM) and a detection limit of 5.95attomolar. The minimum distinguishable response concentration is down to the attomolar level with a high sensitivity and selectivity. We demonstrated that the use of rGO:Y modified electrode along with gold nanoparticle cluster (AuNPC) label leads to the highly sensitive electrochemical detection of BRCA1 gene.

Femtomolar level detection of BRCA1 gene using a gold nanoparticle labeled sandwich type DNA sensor.

We demonstrate the amplified detection of BRCAI gene based on the gold nanoparticle labeled DNA sensor. The sensor was based on a "sandwich" detection strategy, which involved an immobilized capture probe DNA (DNA-c), Target DNA (DNA-t) and gold nanoparticle conjugated reporter probe DNA (DNA-r.AuNP). The sensor surface was characterized by scanning electron microscopy (SEM) and scanning tunneling microscopy (STM). Detection capability of the sensor was studied with I-V measurements using either scanning tunneling microscopy (STM) or Keithley 2400 Source Meter SMU Instrument. The DNA sensor could detect up to 1 fM DNA target (5.896 fg of BRCA 1 gene/ml) and exhibited excellent selectivity against noncomplementary sequences and three base mismatch complementary targets. Good reproducibility, high sensitivity, good stability and reusability of the developed sensor surface showed its application in early cancer diagnosis.