Magnetic N-doped carbon derived from mixed ligands MOF as effective electrochemiluminescence coreactor for performance enhancement of SARS-CoV-2 immunosensor.

COVID-19 as an infectious disease with rapid transmission speed is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), so, early and accurate diagnostics of COVID-19 is quite challenging. In this work, the selective and sensitive self-enhanced ECL method to detect of SARS-CoV-2 protein was designed with magnetic N-doped carbon derived from dual-ligand metal-organic frameworks (MOF) (CoO@N-C) with the primary and tertiary amino groups as a novel coreactant that covalently combined with Ru(bpy)2(phen-NH2)2+ as electrochemiluminescence (ECL) emitter. Mixed-ligand strategy and selected nitrogen-containing ligands, 4,4',4''-((1,3,5-triazine-2,4,6-triyl) tris-(azanediyl)) tribenzoic acid (H3TATAB) with 2-aminoterephthalic acid (BDC-NH2) were used for synthesis of the proposed MOF. Also, magnetic CoO@N-C with high synergistically charge transfer kinetics and good stability can be used as an effective platform/coreactor on the ITO electrode which load more Ru-complex as signal producing compound and SARS-CoV-2 N protein antibody to increase the sensitivity of the immunosensor. Furthermore, (CoO@N-C) as coreactor improved the ECL signal of the Ru (II)-complex more than 2.1 folds compared to tripropylamine. In view of these competences, the novel "on-off" ECL biosensor performed with great stability and repeatability for detection of SARS-CoV-2 protein, which exhibited a broad linearity from 8 fg. mL-1 to 4 ng. mL-1 (6 order of magnitude) and an ultra-low limit of detection 1.6 fg. mL-1. Finally, this proposed method was successfully applied to detect of SARS-CoV-2 N protein in serum sample with satisfactory results, indicating the proposed immunosensor has the potential for quick analysis of SARS-CoV-2.

Synthesis of Chiral Triazine Frameworks for Enantiodiscrimination.

Manipulation of the structure of covalent organic frameworks at the molecular level is an efficient strategy to shift their biological, physicochemical, optical, and electrical properties in the desired windows. In this work, we report on a new method to construct chiral triazine frameworks using metal-driven polymerization for enantiodiscrimination. The nucleophilic substitution reaction between melamine and cyanuric chloride was performed in the presence of PdCl2, ZnCl2, and CuCl2 as chirality-directing agents. Palladium, with the ability of planar complex formation, was able to assemble monomers in two-dimensions and drive the reaction in two directions, leading to a two-dimensional triazine network with several micrometers lateral size. Nonplanar arrangements of monomers in the presence of ZnCl2 and CuCl2, however, resulted in calix and bouquet structures, respectively. While 2D and bouquet structures showed strong negative and positive bands in the CD spectra, respectively, their calix counterparts displayed long-range weak negative bands. In spite of the ability of both calix and bouquet networks to load l-histidine 35 and 50% more than d-histidine from pure enantiomers, respectively, only calix counterparts were able to take up this enantiomer (78%) from the racemic mixture. The two-dimensional polytriazine network did not show any specific interactions with pure enantiomers or their racemic mixtures.

Ultrasensitive Ratiometric Fluorescence Bioassay for Accurate Detection of Covid-19-Specific Nucleocapsid Protein in Clinical Serum Samples Using Modified Cleavable Mesoporous SiO2 Satellite-Enriched Carbon Dots.

Due to the presence of various autofluorescent compounds in biological samples like serum and the photobleaching of organic fluorophores, fluorescence sensing has limited practical applicability. This study describes the development of an improved ratiometric fluorescence assay to determine the nucleocapsid protein (N protein), one of the most conserved biomarkers of Covid-19 in spiked and serum samples using highly stable buffer-based near IR-dual emission carbon dots (CDs) encapsulated into the cavities of cleavable silica nanocapsule (SNCs) nanocomposite. The cavities of cleavable silica nanocapsules (SNCs) and the formed core-shell CDs@ SNCs were used as a superior reservoir of fluorescent markers produced by cohydrolyzing tetraethyl orthosilicate and diiminosilane linker, which held hundreds of CDs in silica shell frameworks. The SiO2 nanocomposite was modified with an N protein antibody that specifically paired to the receptor binding region of the Cov-19 spike protein subunit. CDs were taken out of SNCs by NaBH4 reduction, and the released CDs exhibited dual emission at 475 and 675 nm when excited at 400 nm. Ratiometric detection is completed over a binding-induced, concentration-dependent immuno-affinity of the N protein that drives the fluorescence quenching phenomenon between the CDs as fluorophore and the AuNPs as quencher. As the N protein concentration increased, the intensity of the red emission (675 nm) dropped, whereas the intensity of the green emission (475 nm) already remained constant, which is due to sandwich immunoassays of CDs around AuNPs. Using the exceptional fluorescent characteristics of CDs and the high selectivity of nanocomposite functionalized with N-protein antibody, the developed assay efficiently eliminates the autofluorescence background interference of serum samples. The fluorescence ratio (I475/I675) provides a limit of detection of 2 pg mL-1 over a linear range of 0.01 to 5 ng mL-1 and exhibits an amplified sensitivity of 54 times compared to conventional immunoassay using CDs as fluorescent labels. With one-step signal amplification and requiring small sample quantities (only 20 µL), this sensing platform can be effectively used for the accurate detection of N protein, and no cross-reactivity is detected in the presence of different interfering agents.

Electrochemical monitoring of hydrogen peroxide by a signal-amplified microfluidic chip coupled with colloidal VO2 nanostructures as a peroxidase enzyme mimic.

We present a novel electrochemical microfluidic device for the sensitive and selective detection of hydrogen peroxide (H2O2) through a VO2 nanostructure enzyme mimic. The low-cost ($0.50) microfluidic chip was fabricated using a simple and rapid prototyping technique via three syringe needles. Each needle played the role of an electrode (working, reference, and counter), and was connected by micro-hoses to a construction of the electrochemical microfluidic chip. The colloidal VO2 nanoflakes with peroxidase-like activity could be easily transferred on to the electrodes by a syringe, for development of a novel electrochemical platform to enable the detection of H2O2. The unique microfluidic electrochemical sensor delivered a wide linear dynamic range from 0.5 to 300 µM, with a limit of detection of 0.14 µM. The facile, rapid, sensitive, and selective as-fabricated H2O2 sensors were proven to be appropriate for the real-time monitoring of H2O2 released from PC12 cells. The integration of a microfluidic sensor with an enzyme mimic nanostructure is essentially a promising strategy for the low-cost and accurate monitoring of physiological processes.

Ultrasensitive immunosensor for monitoring of CA 19-9 pancreatic cancer marker using electrolyte-gated TiS3 nanoribbons field-effect transistor.

Measuring CA 19-9 antigen level is critical for early diagnosis of pancreatic cancer, monitoring the treatment process, and predicting disease recurrence. The purpose of this research is to assess the application of novel few-layered TiS3 nanoribbons material as a channel material in electrolyte-gated field-effect transistor immunosensor for rapid detection of CA 19-9 antigen as a cancer marker. Accordingly, TiS3 nanoribbons were produced through liquid-phase exfoliation of as-synthesized TiS3 whiskers in N, N-dimethylformamide. Then, dispersed TiS3 nanoribbons were drop cast onto the FET surface to form an active channel material between source and drain electrodes. Subsequently, the channel surface was modified by utilizing 1-naphthylamine (NA) and glutaraldehyde (GA) to strengthen the binding of monoclonal antibody 19-9 to TiS3 nanoribbons. Spectroscopic and microscopic methods were utilized for comprehensive characterizations. Electrical characterization of electrolyte-gated TiS3 nanoribbons field-effect transistor represented a depletion-mode n-type behavior with field-effect mobility of 0.059 cm2/Vs, current on/off ratio of 10.88 and subthreshold swing (SS) of 450.9 mV/decade. With increasing in CA 19-9 antigen concentration from 1.0 × 10-12 U/mL to 1.0 × 10-5 U/mL, a decrease in the drain current occurred with high sensitivity of 0.04 µA/decade and a detection limit of 1.3 × 10-13 U/mL. Additionally, the proposed TiS3 nanoribbons FET immunosensor exhibited outstanding selectivity, and its good performance was compared with an enzyme-linked immunosorbent assay (ELISA) for spiked real human serum samples. The good and satisfactory obtained results of the proposed immunosensor suggest that the developed platform can be a superb candidate for cancer diagnosis and therapeutic monitoring.

A combined experimental and theoretical study of RuO2/TiO2 heterostructures as a photoelectrocatalyst for hydrogen evolution.

We report a joint experimental and theoretical study of RuO2/TiO2 heterostructures. In the experimental section, mesoporous RuO2/TiO2 heterostructures were prepared by impregnation of mesoporous TiO2 nanoparticles which were synthesized from a new precursor, Na2[Ti(C2O4)3], in an aqueous solution of ruthenium(III) chloride followed by calcination at 300 °C. Using various techniques, the prepared TiO2 and RuO2/TiO2 heterostructures were extensively characterized. The photoelectocatalytic application of the as-prepared heterostructures was then investigated toward the hydrogen evolution reaction (HER). The results illustrated that RuO2 is dispersed uniformly on the TiO2 surface. The loading of RuO2 on TiO2 decreases the band gap energy and extends the absorption edge to the visible light region. This wide absorption extends the photoelectrocatalytic activity of RuO2/TiO2 heterostructures. To obtain a deeper understanding of the increase of the photoelectrocatalytic activity of RuO2/TiO2 heterostructures compared to pure TiO2, theoretical calculations at the density functional theory (DFT) level were performed on some model clusters of pure TiO2 and the RuO2/TiO2 heterostructure. The theoretical results elucidated that the recombination ratio of electron-hole pairs decreases effectively for RuO2/TiO2 compared to pure TiO2.

A novel highly sensitive compilation-detachment fluorescence sensing strategy based on RNA-cleavage DNAzyme for MDA-MB-231 breast cancer biomarker determination.

Herein, we designed a novel and highly sensitive fluorescence multicomponent detachable platform for MDA-MB-231 breast cancer cell detection as a model. The RNA cleavage DNAzyme was used as a central operator of the multicomponent probe through which compilation and induced detachment of probe was done. During the compilation step, the dsDNA-Sybr green 1 complexes on gold nanoparticles (GNP@dsDNA@SG1) were assembled. The intercalated Sybr green in the DNA structure has been used as an amplified signal generator on one site of DNAzyme and magnetic nanoparticles (MNP) act as a biological carrier and probe collector on the opposite side. The enzyme activator co-factor (MDA-MB-231 cell cytoplasmic protein) provokes the activation of the catalytic core of enzyme sequence in the DNAzyme molecule, followed by cleavage reaction in the substrate sequence and releasing GNP@ dsDNA@SG1 into the solution. The results indicate that the Sybr green emission fluorescence (520 nm) increases with the increment of MDA-MB-231 protein concentration in the linear dynamic range of 8.10 × 10-2 to 1.95 ng ml-1 (0.77 × 10-3-0.019 cell ml-1) with a detection limit (LOD) of 1/72 × 10-2 pg ml-1 under optimal conditions. The proposed immunosensor has great potential in developing ultrasensitive and rapid diagnostic platforms.

Electrochemical-based remote biomarker monitoring: Toward Internet of Wearable Things in telemedicine.

Internet of Wearable Things (IoWT) will be a major breakthrough for remote medical monitoring. In this scenario, wearable biomarker sensors have been developing not only to diagnose point-of-care (POC) of diseases, but also to continuously manage them. On-body tracking of biomarkers in biofluids is regarded as a proper substitution of conventional biomarker sensors for dynamic sampling and analyzing due to their high sensitivity, conformability, and affordability, creating ever-rising the market demand for them. In a wireless body area network (WBAN), data is captured from all sensors on the body to a smartphone/laptop, and sent the sensed data to a cloud for storing, processing, and retrieving, and ultimately displayed the data on custom applications (Apps). Wearable IoT biomarker sensors are used for early diseases diagnosis and continuous monitoring in developing countries in which people hardly access to healthcare systems. In this review, we aim to highlight a wide range of wearable electrochemical biomarker sensors, accompanied by microfluidics for continuous sampling, which will pave the way toward developing wearable IoT biomarker sensors to track health status. The current challenges and future perspective in skin-conformal biomarker sensors will be discussing their potential applicability for IoWT in cloud-based telemedicine.

Nano-architecture of MOF (ZIF-67)-based Co3O4 NPs@N-doped porous carbon polyhedral nanocomposites for oxidative degradation of antibiotic sulfamethoxazole from wastewater.

Co3O4 NPs in N-doped porous carbon (Co3O4 NPs@N-PC) materials were prepared by one-pot pyrolysis of a ZIF-67 powder under N2 atmosphere and followed by oxidation under air atmosphere (200 °C) toward promotion catalytic activity and activation of peroxymonosulfate (PMS) to degradation sulfamethoxazole (SMZ). 2-methylimidazole was used as a nitrogen source and a competitive ligand for the synthesis of Co3O4 NPs@N-PC, which in addition to affecting nucleation and growth of the crystal, promotes the production of active Co-N sites. Co3O4 NPs@N-PC nano-architecture has high specific surface areas (250 m2 g-1) and is a non-toxic, effective and stable PMS activator. The effect of operating parameters including SMZ concentration, catalyst dosage, temperature and pH in the presence of Co3O4 NPs@N-PC was investigated. The Co3O4 NPs@N-PC composite showed superior performance in activating PMS over a wide range of pH (2-10) and different temperatures so that complete degradation of SMZ (50 µM, 100 mL) was achieved within 15 min. The role of Co2+/Co3+ redox system in the mechanism before and after PMS activation was determined using XPS analysis. Surface-generated radicals led to the degradation of SMZ, in which the SMZ degradation rate attained 0.21 min-1 with the mineralization of 36.8%. The feasible degradation mechanism of SMZ was studied in the presence of different scavengers and it was revealed that the degradation reaction proceeds from the radical/non-radical pathway and in this process most of the SO4- and OH radicals are dominant. The recoverability and reuse of Co3O4 NPs@N-PC were evaluated to confirm its stability and potential for SMZ degradation and it was observed that the catalyst maintains its catalytic power for at least 5 cycles.

Facile Synthesis of Fe-Doped Hydroxyapatite Nanoparticles from Waste Coal Ash: Fabrication of a Portable Sensor for the Sensitive and Selective Colorimetric Detection of Hydrogen Sulfide.

In this work, a new strategy has been reported for the portable detection of H2S based on Fe-doped hydroxyapatite nanoparticles (Fe-HA) using a colorimetric paper test strip integrated with a smartphone platform. Fe-HA NPs were fabricated successfully via recycling waste coal ash. The obtained probe response toward H2S was through a distinct visual color change. The sensing mechanism is based on the displacement reaction, in which PO4 3- is replaced by S2-. The prepared test strip shows high selectivity, and the other compounds containing thiol and sulfur anion have a negligible effect on the detection of H2S. The designed scheme is applied for H2S detection in the concentration range of 0.5-130 ppm with a limit of detection of 70 ppb. Furthermore, such a disposable sensor was used as a practical system for monitoring H2S in actual water samples, suggesting the promising potential of this platform for suitable analysis of H2S in an aqueous environment.

Injectable Antibacterial Gelatin-Based Hydrogel Incorporated with Two-Dimensional Nanosheets for Multimodal Healing of Bacteria-Infected Wounds.

The design and development of multifunctional injectable hydrogels with high photothermal antibacterial activity and shape adaptability to accelerate bacteria-infected wound healing is of critical importance in clinical applications. In this study, a hybrid hydrogel composed of gelatin, iron, and MnO2 nanosheets was prepared by multiple interactions, including coordinative and hydrogen bonding as well as electrostatic attraction. The introduced MnO2 and Fe components made the hydrogels photothermally and chemodynamically active, thereby endowing them with potent antibacterial capabilities against both Gram-negative and Gram-positive bacteria. Because of the Fenton activity of the hydrogels, they could produce abandoned oxygen, which is highly crucial in the healing process of wounds. They also showed good cytocompatibility and hemocompatibility as well as high hemostatic properties. Moreover, the injectable hydrogels could fill irregular wounds and significantly accelerate bacteria-infected wound healing through decreasing the inflammatory response and increasing blood vessels. These features indicated the promising potential of the multifunctional hydrogel for healing infected full-thickness wounds.

Exploring the Role of 2D-Graphdiyne as a Charge Carrier Layer in Field-Effect Transistors for Non-Covalent Biological Immobilization against Human Diseases.

Graphdiyne's (GDY's) outstanding features have made it a novel 2D nanomaterial and a great candidate for electronic gadgets and optoelectronic devices, and it has opened new opportunities for the development of highly sensitive electronic and optical detection methods as well. Here, we testified a non-covalent grafting strategy in which GDY serves as a charge carrier layer and a bioaffinity substrate to immobilize biological receptors on GDY-based field-effect transistor (FET) devices. Firm non-covalent anchoring of biological molecules via pyrene groups and electrostatic interactions in addition to preserved electrical properties of GDY endows it with features of an ultrasensitive and stable detection mechanism. With emerging new forms and extending the subtypes of the already existing fatal diseases, genetic and biological knowledge demands more details. In this regard, we constructed simple yet efficient platforms using GDY-based FET devices in order to detect different kinds of biological molecules that threaten human health. The resulted data showed that the proposed non-covalent bioaffinity assays in GDY-based FET devices could be considered reliable strategies for novel label-free biosensing platforms, which still reach a high on/off ratio of over 104. The limits of detection of the FET devices to detect DNA strands, the CA19-9 antigen, microRNA-155, the CA15-3 antigen, and the COVID-19 antigen were 0.2 aM, 0.04 pU mL-1, 0.11 aM, 0.043 pU mL-1, and 0.003 fg mL-1, respectively, in the linear ranges of 1 aM to 1 pM, 1 pU mL-1 to 0.1 µU mL-1, 1 aM to 1 pM, 1 pU mL-1 to 10 µU mL-1, and 1 fg mL-1 to 10 ng mL-1, respectively. Finally, the extraordinary performance of these label-free FET biosensors with low detection limits, high sensitivity and selectivity, capable of being miniaturized, and implantability for in vivo analysis makes them a great candidate in disease diagnostics and point-of-care testing.

Paper-based broadband flexible photodetectors with van der Waals materials.

Layered metal chalcogenide materials are exceptionally appealing in optoelectronic devices thanks to their extraordinary optical properties. Recently, their application as flexible and wearable photodetectors have received a lot of attention. Herein, broadband and high-performance paper-based PDs were established in a very facile and inexpensive method by rubbing molybdenum disulfide and titanium trisulfide crystals on papers. Transferred layers were characterized by SEM, EDX mapping, and Raman analyses, and their optoelectronic properties were evaluated in a wavelength range of 405-810 nm. Although the highest and lowest photoresponsivities were respectively measured for TiS3 (1.50 mA/W) and MoS2 (1.13 µA/W) PDs, the TiS3-MoS2 heterostructure not only had a significant photoresponsivity but also showed the highest on/off ratio (1.82) and fast response time (0.96 s) compared with two other PDs. This advantage is due to the band offset formation at the heterojunction, which efficiently separates the photogenerated electron-hole pairs within the heterostructure. Numerical simulation of the introduced PDs also confirmed the superiority of TiS3-MoS2 heterostructure over the other two PDs and exhibited a good agreement with the experimental results. Finally, MoS2 PD demonstrated very high flexibility under applied strain, but TiS3 based PDs suffered from its fragility and experience a remarkable drain current reduction at strain larger than ± 0.33%. However, at lower strains, all PDs displayed acceptable performances.

Understanding the bulk and interfacial structures of ternary and binary deep eutectic solvents with a constant potential method: a molecular dynamics study.

In the last decade, deep eutectic solvents (DESs) have emerged as promising electrolytes in supercapacitors and rechargeable batteries due to their unique properties, wide electrochemical windows, low viscosity, and high ionic conductivity. The molecular structural behavior of these solvents, which plays an important role in their efficiency is not deeply understood. Therefore, in this work, by considering two types of DES electrolytes, we investigate their bulk and interfacial structures at the molecular level using molecular dynamics studies. In this regard, two different DESs-a binary DES including choline chloride and urea in a 1 : 2 molar ratio, and a ternary DES containing choline chloride, urea, and ethylene glycol with a molar ratio of 1 : 1 : 2-are considered. For the bulk phase, the partial site-site and center of mass radial distribution functions (RDFs), the mean square displacement (MSD), and the self-diffusion coefficient of the ternary system are explored. We demonstrate that in deep eutectic solvents, in addition to hydrogen-bonding and long-range and short-range correlations, a variety of neutral species play crucial roles in the properties of the bulk phase. Furthermore, considering two graphene sheets as electrodes on both sides of the DES samples, the profiles of the number density, charge density, orientational order parameter, and electrostatic potentials at different potential conditions near the electrodes are investigated. The results reveal the presence of multilayers of the neutral species in the vicinity of electrodes in addition to the ionic components of both DES systems. Finally, the computed differential capacitances (Cd) for DESs disclose that the positive electrode capacitance is higher than that of the negative electrode, and in the ternary system, the total capacitance is greater than in the binary system. Our findings give a better perspective of a new generation of electrolytes at the molecular level for electric double-layer capacitors.

Carbon dots hybrid for dual fluorescent detection of microRNA-21 integrated bioimaging of MCF-7 using a microfluidic platform.

BACKGROUND: MicroRNAs have short sequences of 20 ~ 25-nucleotides which are similar among family members and play crucial regulatory roles in numerous biological processes, such as in cell development, metabolism, proliferation, differentiation, and apoptosis. RESULTS: We reported a strategy for the construction of a dual-emission fluorescent sensor using carbon dots (CDs) and confirmed their applications for ratiometric microRNA-21 sensing and bioimaging of cancer cells in a microfluidic device. The composition of blue CDs (B-CDs) and yellow CDs (Y-CDs) depicts dual-emission behavior which is centered at 409 and 543 nm under an excitation wavelength of 360 nm. With increasing microRNA-21 concentration, the robust and specific binding of DNA probe functionalized B-CDs to complementary microRNA-21 target induced perturbations of probe structure and led to changing fluorescence intensity in both wavelengths. Consequently, the ratio of turn-on signal to turn-off signal is greatly altered. With monitoring of the inherent ratiometric fluorescence variation (ΔF540nm/ΔF410nm), as-prepared BY-CDs were established as an efficient platform for ratiometric fluorescent microRNA-21 sensing, with a wide linear range of 0.15 fM to 2.46 pM and a detection limit of 50 aM. CONCLUSIONS: Furthermore, the proposed assay was applied for detecting microRNA-21 in dilute human serum samples with satisfactory recovery and also in MCF-7 cell lines in the range 3000 to 45,000 (cell mL-1) with a detection limit (3 cells in 10 µL), demonstrating the potential of the assay for clinic diagnosis of microRNA-associated disease. More importantly, the images revealed that MCF-7 cells well labeled with BY-CDs could exhibit the applicability of the proposed microfluidic system as an effective cell trapping device in bioimaging.

Development of three-dimensional semi-solid hydrogel matrices for ratiometric fluorescence sensing of Amyloid ß peptide and imaging in SH-SY5 cells: Improvement of point of care diagnosis of Alzheimer's disease biomarker.

Alzheimer's is a neurodegenerative disease with high morbidity and mortality in the elderly, so, detection of its biomarker for definite diagnosis of Alzheimer's in the early stage of disease is a challenge. Amyloid beta peptide (Aß) chosen as an Alzheimer's biomarker. Here, we developed novel, semi-solid, three-dimensional hydrogel matrices for ratiometric fluorescence detection of Aß. This assay's great performance stems from the employment of a hybrid conjugate composed of Rhodamine B (RB), Carbon dots (CDs), and an Aß probe entrapped in Polyvinyl alcohol (PVA), and then detection of fluorescence resonance energy transfer (FRET) that occurs in the presence of AuNP/target-Aß, as a result of hybridization. The RB-CDs' fluorescence (at 582 nm and 675 nm under 430 nm excitation) is quenched in the presence of AuNPs, while the ratio of fluorescence (I582/I675) is increased by the addition of Aß target, and shows a linear relationship in the range of 75 pM-250 nM, with a detection limit of 0.5 pM. Furthermore, the assay possesses strong selectivity for Aß compared to other proteins, and different quantities of a human serum sample successfully analyzed with excellent sensitivity, satisfactory precision, and reliability. Due to distribution of Aß in SH-SY5 human neuroblastoma cells, extending this UV-Vis-NIR full-range responsive CDs bio-probe to imaging of Aß in cells. In both fixed and living SH-SY5 cells, the nanoprobe delivers a clear signal to the Aß target. Because of its high sensitivity, selectivity, biocompatibility and affordability, this nanoprobe is a good option for early Alzheimer's disease diagnosis.

A Chelation-enhanced Fluorescence Assay using Thiourea Capped Carbonaceous Fluorescent Nanoparticles for As (III) Detection in Water Samples.

Herein, we designed a sensitive and selective "Turn-On" fluorescence nanosensor using water-soluble carbonaceous fluorescent nanomaterials (CFNs) functionalized with thiourea (CFNs-Thiourea) for efficient detection of trace concentrations of arsenic (III) in aqueous samples. The CFNs and CFNs-Thiourea were characterized by transmission electron microscopy (TEM), UV-visible spectroscopy (UV-vis) and fourier transformed infrared spectroscopy (FTIR). The emission peak intensity of proposed nanosensor at 425 nm was gradually enhanced on arsenite addition in a wide detection range (3.3-828.5 µg L-1) attributed to the binding of arsenite species with sulfur groups of CFNs-Thiourea. The limit of detection (LOD) was 0.48 µg L-1 being much lower than the World Health Organization (WHO) recommended threshold value of 10 µg L-1. Furthermore, the as-prepared CFNs-Thiourea exhibited a superb selectivity for As (III) compared to various cations and anions, such as; NO3-, NO2-, F-, Ni2+, Fe3+, Cu2+, Ca2+, Mg2+, Zn2+, Fe2+, Hg2+, Pb2+, F-, Cl-, Mn2+, Cr3+, Co2+, Cd2+, Bi3+, Al3+ and As (V) at 100 folds concentration of As (III). The turn on fluorescence nanosensor was successfully exploited for quantification of arsenic in spiked water samples with acceptable efficiencies.

Graphdiyne nanosheet as a novel sensing platform for self-enhanced electrochemiluminescence of MOF enriched ruthenium (II) in the presence of dual co-reactants for detection of tumor marker.

Graphdiyne (GDY) is a new two-dimensional carbon material with high charge carrier mobility, excellent conductivity, more suitable band gap, and natural pores was introduced as a new electrochemiluminescent sensing platform. Herein, the metal organic framework (MOFs) used for enrichment of luminophore with grafting Ru(bpy)2(phen-NH2)2+(Ru-complex) and Ru-complex amine-rich nitrogen-doped carbon nanodots(Ru-NCNDs) via both encapsulating and external decoration and decoration of SmS2 QDs as coreactant. Then, the MOF enriched Ru-complex (Ru@MOF@NCNDs-Ru@SmS2 QD) located on a GDY modified ITO electrode developed as a novel and efficient ECL platform. According to the Density Functional Theory (DFT) calculation, the band gap of graphdiyne/Ru(bpy)2(phen-NH2)2+ system decreased compared to graphdiyne, Ru-complex and also graphene oxide/Ru(bpy)2(phen-NH2)2+system, which enhanced (2 folds) the signal response of the presented ECL platform. The ECL response signal of the suggested emitter with high ECL efficiency (13.34%) increased 8 and 4 folds compared to GDY/Ru-NCNDs and GDY/Ru@MOF@NCNDs-Ru as platforms, respectively. The proposed ECL platform applied for CA19-9 antigens detection at concentration range 0.0005 UmL-1 to 200 UmL-1 and detection limit of 0.00013 UmL-1.The development of GDY based platform for decorating nano luminophores, not only provides the design of ECL luminophores with high performance but also promises the application of the presented strategy for fabrication of ultrasensitive bio affinity sensors as candidates in clinical monitoring and diseases diagnostics.

CuO/Cu-MOF nanocomposite for highly sensitive detection of nitric oxide released from living cells using an electrochemical microfluidic device.

The integration of large surface area and high catalytic profiles of Cu-MOF and CuO nanoparticles is described toward electrochemical sensing of nitric oxide (NO) in a microfluidic platform. The CuO/Cu-MOF nanocomposite was prepared through hydrothermal method, and its formation was confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). The CuO/Cu-MOF nanostructured modified Au electrodes enabled electrocatalytic NO oxidation at 0.6 V vs. reference electrode, demonstrating linear response over a broad concentration range of 0.03-1 µM and 1-500 µM with a detection limit of 7.8 nM. The interference effect of organic molecules and common ions was negligible, and the sensing system demonstrated excellent stability. Finally, an electrochemical microfluidic NO sensor was developed to detect of NO released from cancer cells, which were stimulated by L-arginine. Furthermore, in the presence of Fe3+, the stressed cells produced more NO. This work offers considerable potential for its practical applications in clinical diagnostics through determination of chemical symptoms in microliter-volume biological samples. Electrochemical microfluidic NO sensor was developed for detection of NO released from cancer cells. This miniaturized device consumes less materials and provides the basis for greener analytical chemistry.

Ultrasensitive molecularly imprinted fluorescence sensor for simultaneous determination of CA125 and CA15-3 in human serum and OVCAR-3 and MCF-7 cells lines using Cd and Ni nanoclusters as new emitters.

In the clinical diagnosis of tumors, a single-marker immunoassay may lead to false results. Thus there is a need for an effective and valid method for the simultaneous measurement of multiple tumor markers. In this work, an efficient fluorescence immunosensor for the simultaneous measurement of CA125 and CA15-3 tumor markers was fabricated by utilizing the high selectivity of magnetic molecularly imprinted polymers (MMIPs) and the high sensitivity of a fluorescence (FL) method. Ni nanoclusters (Ni NCs) and noble Cd nanoclusters (Cd NCs) were introduced as efficient and economic emitters, and magnetic graphene oxide (GO-Fe3O4) was applied as a support material for surface molecularly imprinted polymers. Under the most favorable experimental conditions, the fluorescence intensity of the Cd NCs and Ni NCs gradually increased with increasing concentration of CA125 and CA15-3 antigens at a range of 0.0005-40 U mL-1, respectively, with a limit of detection (LOD) of 50 µU mL-1. The developed method had excellent properties including a broad linear range, good reproducibility, and simple operation for the clinical diagnosis of CA 125 and CA 15-3 tumor markers. This molecularly imprinted fluorescence sensor has the potential to be an effective clinical tool for the timely screening of breast cancer in human serum samples and OVCAR-3 and MCF-7 cell lines, and can be applied in clinical diagnostics.