Host-Guest Mechanism via Induced Fit Fullerene Complexation in Porphin Receptor to Probe Salivary Alpha-Amylase in Dental Caries for Clinical Applications

Salivary α-amylase is the most abundant protein of human saliva that potentially binds to streptococcus and other bacteria via specific surface-exposed α-amylase-binding proteins and plays a significant role in caries development. The detection of α-amylase in saliva can be used as a bioindicator of caries development. Herein, a facile strategy has been applied, tailoring the photochemical properties of 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine (TPPOH) and the fullerene C60 complex. The fluorescence emission of TPPOH is quenched by starch-coated fullerene C60 via charge-transfer effects, as determined by UV absorption and fluorescence spectroscopic studies. The starch-coated C60 has been thoroughly characterized via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), optical microscopy, thermal gravimetric analysis (TGA), static water contact angle measurements, and zeta potential measurements. The analytical response of the assay showed a linear fluorescent response in α-amylase concentrations ranging from 0.001-0.1 Units/mL, with an LOD of 0.001 Units/mL. The applicability of the method was tested using artificial saliva with quantitative recoveries in the range 95-100%. The practicability of the procedure was verified by inspecting saliva samples of real clinical samples covering all age groups. We believe that the proposed method can serve as an alternative analytical method for caries detection and risk assessment that would also minimize the cost of professional preventive measures and treatments.

Tailoring molecular recognition in predesigned multifunctional enzyme mimicking porphyrin imprinted interface for high affinity and differential selectivity; sensing etoposide in lung cancer patients

Nanozymes are cost-effective and robust but they lack specificity and selectivity, limiting their potential practical applications. Herein, molecularly imprinted polymers (MIPs) were grown in combination with multifunctional 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin (THPP) oxidase-like nanozyme to engineer THPP@MIP interface with high affinities and differential selectivity for structurally related target analytes. THPP nanozyme displayed a high level of predefined binding affinity for etoposide (ETO), and served as a predesigned functional monomer to rationally tailor the selectivity of THPP@MIP surface in the presence of different guest molecules. THPP nanozyme in combination with conventional monomers was imprinted on a portable and disposable cellulose paper matrix under UV light to create a UV-cured imprinted interface for optical detection of ETO. The THPP@MIP enzyme mimicking interface, having ETO specific and selective target recognition pockets, catalyzed the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to generate visible blue oxidized TMB (oxTMB) without exogenous hydrogen peroxide (H2O2). The ETO binding on the THPP@MIP surface blocked the channels for TMB access to THPP cavities. The THPP@MIP sensor permitted to detect ETO in the linear range of 0.005-10 μg mL-1, with a limit of detection (LoD) of 0.002 μg mL-1, and showed a remarkable specificity and selectivity against other drug molecules. Furthermore, the THPP@MIP sensor successfully differentiated the serum samples of lung cancer patients and healthy volunteers. The obtained results were validated with standard High performance liquid chromatography-mass spectrometry (HPLC/MS) analysis of the serum samples. Additionally, ETO injection/infusion solutions and ETO-free serum samples were used to perform the matrix effect and recovery studies. This work demonstrates that molecular imprinting with predesigned, enzyme mimicking, high-affinity functional monomer can serve as a highly selective and specific universal interface for broad spectrum sensing applications in various analytical domains.

Growth of diazonium-functionalized ZnO nanoflakes on flexible carbon cloth for electrochemical sensing of acetone in the liquid phase

Simple detection of acetone is indispensable due to its health and environmental concerns. Surface-modified electrodes are promising for the detection of acetone. In the present study, the facile fabrication of ZnO nanoflakes on carbon cloth (CC) is reported. The electrode was fabricated by decorating the CC with ZnO nanoparticles (ZnO NPs), followed by the hydrothermal treatment and modification with diazonium salt using linear sweep voltammetry (LSV) forming ZnO nanoflakes (ZnO NFs) on ZnO NPs/CC. The as-prepared ZnO/CC electrode was used for the detection of acetone at room temperature using cyclic voltammetry. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analyses were used for the chemical and physical characterization of the CC before and after each modification step. The obtained data manifested that ZnO NFs functionalized with diazonium salt increased the roughness of the CC surface, which was advantageous to promote the interaction between CC and acetone target. The modified sensing platform showed excellent performance in terms of the wide working range (0.1-2000 ppm) and low detection limit (0.03 ppm), making it a promising and cost-effective sensor of acetone in the liquid phase.

Fabrication of polydopamine decorated carbon cloth as support material to anchor CeO2 nanoparticles for electrochemical detection of ethanol

A flexible CeO₂ nanostructured polydopamine-modified carbon cloth (CeO₂/PDA/CC) interface was fabricated via electrodeposition for ethanol detection. The fabrication method involved two consecutive electrochemical steps in which dopamine was firstly electrodeposited on carbon fibers, followed by the electrochemical growth of CeO₂ nanoparticles. The CeO₂/PDA-based electroactive interface exerts an impressive electrochemical performance on the flexible sensor due to strong synergistic effect of the PDA functionalization with more active sites. Moreover, catalytic activity of CeO₂ nanostructures anchored on highly conductive CC incorporate superior electrocatalytic performance of the fabricated interface. The designed electrochemical sensor showed a wide response to ethanol in the linear range 1 to 25 mM with a detection limit of 0.22 mM. The CeO₂/PDA/CC flexible sensor showed good anti-interference ability and excellent repeatability and reproducibility (RSD = 1.67%). The fabricated interface performed well in saliva samples with satisfactory recoveries, corroborating the viability of CeO₂/PDA/CC integrated interface for practical implementation.

In-situ synthesized ZIF-67 graphene oxide (ZIF-67/GO) nanocomposite for efficient individual and simultaneous detection of heavy metal ions

Heavy metals are ubiquitous in water bodies as a result of anthropogenic activities and over time they accumulate in body thus posing serious health problems. Therefore, it is essential to improve sensing performance, for determination of heavy metal ions (HMIs), of electrochemical sensors. In this work, cobalt-derived MOF (ZIF-67) was in-situ synthesized and incorporated onto the surface of graphene oxide (GO) by simple sonication method. The prepared material (ZIF-67/GO) was characterized by FTIR, XRD, SEM, and Raman spectroscopy. Afterwards, a sensing platform was made by drop-casting synthesized composite onto glassy carbon electrode for individual and simultaneous detection of heavy metal ions pollutants (Hg²⁺, Zn²⁺, Pb²⁺, and Cr³⁺) with estimated detection limits of 2 nM, 1 nM, 5 nM, and 0.6 nM, respectively, when determined simultaneously, that are below the permissible limit by World Health Organization. To the best of our knowledge, this is first report of HMIs detection by ZIF-67 incorporated GO sensor which can successfully determine the Hg⁺², Zn⁺², Pb⁺², and Cr⁺³ ions simultaneously with lower detection limits.

Graphene oxide reinforced silk fibroin nanocomposite as an electroactive interface for the estimation of dopamine

The fabrication of 2D materials and polymer-based nanocomposites deposited on flexible conductive interfaces has unblocked new horizons to expedite reaction kinetics for developing highly selective and sensitive electrochemical biosensors. Herein, we developed a novel biosensing platform, comprising graphene oxide and a silk fibroin-based nanocomposite, drop-cast on a carbon cloth electrode. The fabricated interface was expected to be a robust and miniaturized sensing platform for precise detection of dopamine (DA). Characterization was performed by SEM, EDX, FTIR, XRD, UV-visible spectroscopy, contact angle measurement, fluorescence spectroscopy, particle size, and zeta potential analysis. CV, EIS, DPV, and chronoamperometry demonstrated the superior electrochemical properties of the working interface and revealed its enhanced active surface area, increased conductivity, and accelerated electron transfer rate. The designed interface exhibited low LoD (0.41 μM), admirable stability, good sensitivity (2.46 μA μM^-1 cm^-2), wide linearity ranging from 100-900 μM, excellent reproducibility, and superb selectivity against dopamine even in the presence of possible interfering analytes. These findings endorse the feasibility of the practical execution of such an integrated system in real sample analysis.

Multifunctional Smart ZnSe-Nanostructure-Based Fluorescent Aptasensor for the Detection of Ochratoxin A

Herein, we present a comprehensive investigation of rationally designed zinc selenide (ZnSe) nanostructures to achieve highly negatively charged ZnSe nanostructures. A Microwave-assisted hydrothermal synthesis method was used to synthesize three types of ZnSe nanostructures, i.e., nanorods, µ-spheres and nanoclusters, as characterized by a zeta potential analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and BET, which were labeled as type A, B and C. Three different solvents were used for the synthesis of type A, B and C ZnSe nanostructures, keeping other synthesis conditions such as temperature, pressure and precursors ratio constant. Based on two heating time intervals, 6 and 9 h, types A, B and C were further divided into types A6, A9, B6, B9, C6 and C9. ZnSe nanostructures were further evaluated based on their fluorescent quenching efficiency. The maximum fluorescence quenching effect was exhibited by the ZnSe-B6 type, which can be attributed to its highly negative surface charge that favored its strong interaction with cationic dye Rhodamine B (Rh-B). Further, the optimized ZnSe-B6 was used to fabricate an aptasensor for the detection of a food-based toxin, ochratoxin-A (OTA). The developed aptasensor exhibited a limit of detection of 0.07 ng/L with a wide linear range of 0.1 to 200 ng/L.

Functionalized organic filler based integrated membranes for environmental remediation

Mixed matrix membranes (MMMs) are synthesized for efficient CO₂ separation released from various anthropogenic sources, which are due to global environmental concerns. The synergetic effect of porous nitrogen-rich, CO₂-philic filler and polymer in mixed matrix-based membranes (MMMs) can separate CO₂ competent. The development of various loadings of porphyrin poly(N-isopropyl Acryl Amide) (P-NIPAM)as functionalized organic fillers (5-20%) in polysulfone (PSU) through solution casting is carried out followed by the various characterizations including field emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), Fourier Transform Infrared Spectrometer(FT-IR) analysis and pure and mixed gas permeations ranging from 2 to 10 bar feed pressure. Due to both organic species interactions in the matrix, well-distributed fillers and homogenous surfaces, and cross-sectional structures were observed due to π-π interactions and Lewis's basic functionalities. The strong affinity of porous nitrogen-rich and CO₂-philic fillers through gas permeation analysis showed high CO₂/CH₄ and CO₂/N₂ gas performance that surpassed Robeson's upper bound limit. Comparatively, MMMs showed improved CO₂/CH₄ permeabilities from 87.5 ± 0.5 Barrer to 88.2 ± 0.9 Barrer than pure polymer matrix. For CO₂/N₂, CO₂ permeabilities improved to 75 ± 0.8 Barrer than pure polymer matrix. For both gas pairs (CO₂/CH₄, CO₂/N₂), respective pureselectivities (84%; 86%) and binary selectivities (85% and 85%)were improved. Various theoretical gas permeation models were used to predict CO₂ permeabilities for MMMs from which the modified Maxwell-Wagner-Sillar model showed the least AARE% of 0.87. The results showed promising results for efficient CO₂ separation due to exceptional functionalized P-PNIPAM affinitive properties. Finally, cost analysis reflected the inflated cost of membranes production for industrial setup using indigenous resources.

Nickel -doped iron oxide nanoparticle-conjugated porphyrin interface (porphyrin/Fe2O3@Ni) for the non-enzymatic detection of dopamine from lacrimal fluid

Herein, we synthesized nickel (Ni)-doped iron oxide nanoparticles (Fe₂O₃). The presence of the dopant afforded anchoring sites for the porphyrinic hetero cavity of 5,10,15,20-(tetra-4-carboxyphenyl)porphyrin to produce the porphyrin/Fe₂O₃@Ni composite. The crystalline structure and morphology of porphyrin/Fe₂O₃@Ni were assessed using various tools including Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy. Porphyrin/Fe₂O₃@Ni has proven to be an excellent dopamine (DA) probe material with good selectivity, reproducibility, stability and reliability owing to its clever morphology, which induces numerous active sites along with good active surface area. It consequently provides good accessibility to DA and allows for the smooth tunneling of electrons between the analyte and sensing interface. Meanwhile, the porphyrin molecules provide good carbon-based resilient support, inhibit the leaching of the electrode matrix and enhance electron shuttling, resulting in the robust oxidation of DA with amplified transduction signals. The designed porphyrin/Fe₂O₃@Ni interface showed a low detection limit (1.2 nm) with good sensitivity (1.2 nM) in the linear bounds of 10 μM to 3500 μM. Additionally, the interface was employed successfully to analyze DA from lacrimal fluid with good percentage recoveries (99.8% to 100.1%). We anticipate that such a design will simplify the in vitro screening of DA in rarely studied tear samples with sensitivity and selectivity.

Insight into prognostics, diagnostics, and management strategies for SARS CoV-2

The foremost challenge in countering infectious diseases is the shortage of effective therapeutics. The emergence of coronavirus disease (COVID-19) outbreak has posed a great menace to the public health system globally, prompting unprecedented endeavors to contain the virus. Many countries have organized research programs for therapeutics and management development. However, the longstanding process has forced authorities to implement widespread infrastructures for detailed prognostic and diagnostics study of severe acute respiratory syndrome (SARS CoV-2). This review discussed nearly all the globally developed diagnostic methodologies reported for SARS CoV-2 detection. We have highlighted in detail the approaches for evaluating COVID-19 biomarkers along with the most employed nucleic acid- and protein-based detection methodologies and the causes of their severe downfall and rejection. As the variable variants of SARS CoV-2 came into the picture, we captured the breadth of newly integrated digital sensing prototypes comprised of plasmonic and field-effect transistor-based sensors along with commercially available food and drug administration (FDA) approved detection kits. However, more efforts are required to exploit the available resources to manufacture cheap and robust diagnostic methodologies. Likewise, the visualization and characterization tools along with the current challenges associated with waste-water surveillance, food security, contact tracing, and their role during this intense period of the pandemic have also been discussed. We expect that the integrated data will be supportive and aid in the evaluation of sensing technologies not only in current but also future pandemics.

Fabrication of ionic liquid stabilized MXene interface for electrochemical dopamine detection

Development of MXene (Ti3C2Cl2)-based sensing platforms by exploiting their inherent active electrochemistry is highly challenging due to their characteristic poor stability in air and water. Herein, we report a cost-effective methodology to deposit MXene on a conductive graphitic pencil electrode (GPE). MXenes can provide active surface area due to their clever morphology of accordion-like sheets; however, the disposition to stack together limits their potential applications. A task-specific ionic liquid (1-methyl imidazolium acetate) is utilized as a multiplex host material to engineer MXene interface via π-π interactions as well as to act as a selective binding site for biomolecules. The resulting IL-MXene/GPE interface proved to be a highly stable interface owing to good interactions between MXene and IL that inhibited electrode leaching and boosted electron transfer at the electrode-electrolyte interface. It resulted in robust dopamine (DA) oxidation with amplified faradaic response and enhanced sensitivity (9.61 µA µM-1 cm-2) for DA detection. This fabricated sensor demonstrated large linear range (10 µM - 2000 µM), low detection limit (702 nM), high reproducibility, and good selectivity. We anticipate that such platform will pave the way for the development of stable and economically viable MXene-based sensors without sacrificing their inherent properties. Scheme 1 Schematic illustration of the IL-MXene/GPE fabrication and oxidative process towards non-enzymatic dopamine sensor.

N-Doped graphene quantum dots (N-GQDs) as fluorescent probes for detection of UV induced DNA damage

UV induced DNA damage can lead to the development of skin cancer, skin aging and cell death. In this study, we fabricated a fluorescence-based biosensor that can be applied to the detection of DNA damage caused by UV radiation with the help of nitrogen doped graphene quantum dots (N-GQDs) as the probe material. In this paper, N-GQDs with good fluorescence efficiency have been synthesized by the hydrothermal method and were used as a fluorescent probe for the detection of UV damaged DNA. The fluorescence intensity of N-GQDs was quenched by the static quenching of UV damaged DNA through the formation of a N-GQD/UV damaged DNA complex. Moreover, the effects of different values of pH, NaCl and glucose on analytical performances of the sensor were also studied. Thus, using a fluorescence based approach, we demonstrated a quite simple, rapid, and inexpensive biosensor for the detection of DNA damage caused by UV radiation.

UV induced DNA damage can lead to the development of skin cancer, skin aging and cell death.

Functionalized thiazolidone-decorated lanthanum-doped copper oxide: novel heterocyclic sea sponge morphology for the efficient detection of dopamine

Herein, we synthesized lanthanum (La)-doped sea sponge-shaped copper oxide (CuO) nanoparticles and wrapped them with novel O-, N- and S-rich (2Z,5Z)-3-acetyl-2-((3,4-dimethylphenyl)imino)-5-(2-oxoindolin-3-ylidene)thiazolidin-4-one (La@CuO-DMT). The shape and composition of the designed materials were confirmed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and Raman spectroscopy. The graphitic pencil electrode (GPE) fabricated using La@CuO-DMT showed excellent sensing efficacy against dopamine (DA) with good selectivity, reproducibility and ideal stability. The unique morphology and massive surface defects by La@CuO offer good accessibility to DA and enhance smooth and robust channeling of electrons at the electrode–electrolyte interface. Consequently, these properties resulted in improved reaction kinetics and robust DA oxidation with an amplified faradaic response. Meanwhile, O-, N-, and S-enriched carbon support, i.e. DMT, inhibited the leaching of electrode matrixes, resulting in a superior detection limit of 423 nm and an improved sensitivity of 13.9 μA μM⁻¹ cm⁻² in the linear range of 10 μM to 1500 μM. Additionally, the developed sensing interface was successfully employed to analyze DA from tear samples with excellent percentage recoveries. We expect that such engineered morphology-based nanoparticles with a O-, N-, and S-rich C support will facilitate the development of DA sensors for in vitro screening of rarely studied tear samples with good sensitivity and selectivity.

Sea sponge-shaped La@CuO-decorated O-, N-, and S-rich DMT-wrapped GPE for DA detection.

Copper oxide integrated perylene diimide self-assembled graphitic pencil for robust non-enzymatic dopamine detection

Exploring a robust, extremely sensitive, cost-effective and reliable assay platform for the precise analysis of dopamine (DA) has become a big challenge predominantly at the clinical level. To participate in this quest, herein, we fabricated a perylene diimide (PDI) self-assembled graphitic surface of the graphitic pencil electrode (GPE) anchored copper oxide (CuO). The self-assembled N-rich PDI led to the fast movement of ions by decreasing the bandgap and improved the electron transport kinetics with more exposed catalytic active sites, thus resulting in the robust electrochemical sensing of DA. The designed sensor exhibited good sensitivity (4 μM⁻¹ cm⁻²), high structural stability, repeatability and excellent reproducibility with an RSD value of 2.9%. Moreover, the developed system showed a wide linear range (5 μM to 500 μM) and reliable selectivity even in the presence of co-existing interferants, such as ascorbic acid and uric acid. The fabricated nanohybrid was eventually employed to analyze DA in spiked physiological fluids and provided satisfactory recoveries. The designed PDI-CuO based interface also showed a very low detection limit of 6 nM (S/N = 3), consequently confirming its suitability for clinical and biological applications.

Exploring a robust, extremely sensitive, cost-effective and reliable assay platform for the precise analysis of dopamine (DA) has become a big challenge predominantly at the clinical level.

Sustainable mixed matrix membranes containing porphyrin and polysulfone polymer for acid gas separations

The synergetic effect of nitrogen-rich and CO₂-philic filler and polymer in mixed matrix-based membranes (MMMs) can separate CO₂ competently. The introduction of well-defined nanostructured porous fillers of pores close to the kinetic diameter of the gas molecule and polymer matrix compatibility is a challenge in improving the gas transportation characteristics of MMMs. This study deals with the preparation of porphyrin filler and the polysulfone (PSf) polymer MMMs. The fillers demonstrated uniform distribution, uniformity, and successful bond formation. MMMs demonstrated high thermal stability with a glass transition temperature in the range of 480-610 °C. The porphyrin filler exhibited microporous nature with the presence of π-π bonds and Lewis's basic functionalities between filler-polymer resulted in a highly CO₂-philic structure. The pure and mixed gas permeabilities and selectivity were successfully improved and surpass the Robeson's upper bound curve's tradeoff. Additionally, the temperature influence on CO₂ permeability revealed lower activation energies at higher temperatures leading to the gas transport facilitation. This can be granted consistency and long-term durability in polymer chains. These results highlight the unique properties of porphyrin fillers in CO₂ separation mixed matrix membranes and offer new knowledge to increase comprehension of PSf performance under various contents or environments.

Fluorescence quenching mediated detection of hydrogen peroxide using tungsten incorporated graphitic carbon nitride nanoflakes

A reliable, non-enzymatic detection for H₂O₂ with high sensitivity and accuracy is of profound importance and getting considerable interest due to its usefulness in biological systems. Therefore, this work was aimed to develop a sensitive method for the detection of H₂O₂ using rhodamine B as a fluorescence system and tungsten doped graphitic carbon nitride (W/GCN) as catalysts. Fluorescence quenching and colorimetric properties of the chromogenic-dye probe were used as a detection strategy of H₂O₂. The enhanced catalytic property of nanoflakes of W/GCN was attributed to the unique structural characteristics, influenced by the dopant, that not only tuned its bandgap but also enhanced separation of electron-hole pairs as compared to planar and larger sized nanosheets of pristine GCN. This low-cost and rapid assay offered a very low limit of detection of 8 nM for the fluorescence quenching method and 20 nM for the colorimetric method. The linear range for fluorescence quenching and colorimetric H₂O₂ assays were from 10-500 nM and 35-400 nM, respectively. Therefore, this novel method of using W/GCN nanoflakes in fluorescence quenching and colorimetric based detections of H₂O₂ is expected to catch more interest on the topic of using non-enzymatic platforms for sensitive and selective detection of different analysts.

N-Doped Graphene Oxide Decorated with PtCo Nanoparticles for Immobilization of Double-Stranded Deoxyribonucleic Acid and Investigation of Clenbuterol-Induced DNA Damage

We demonstrate here a facile hydrothermal-assisted formation of PtCo alloy nanoparticles (NPs) and their simultaneous anchoring on the graphitic surface of N-doped graphene oxide (NGO). Doping induced nanopores in the carbon surface to facilitate the uniform and homogeneous anchoring of alloy nanoparticles. It was revealed that the formation of PtCo NPs on an NGO interface plodded excellent tendency toward double-stranded deoxyribonucleic acid (dsDNA). The dsDNA immobilization was enabled by the presence of several oxidation states of Pt and Co. The same property was further used to monitor the direct detection of dsDNA damage induced by clenbuterol via screen-printed carbon electrodes. Cyclic voltammetric and electrochemical impedance spectroscopic characterization traced well the dsDNA attachment on the modified electrode surface. Differential pulsed voltammetry was further used as a tool to monitor the characteristic guanine peak before and after incubating with clenbuterol used as a damage probe for the dsDNA. The findings can further be appurtenant in exploring dsDNA immobilization protocols and developing analytical methods for determination of various dsDNA damaging agents.

A nanocomposite prepared from magnetite nanoparticles, polyaniline and carboxy-modified graphene oxide for non-enzymatic sensing of glucose

The authors report on the synthesis of carboxy functionalized graphene oxide (fGO) decorated with magnetite (Fe₃O₄) nanoparticles. The resulting nanomaterial was used to prepare a composite with polyaniline (PANI) which was characterized by UV-vis, Fourier transform-infrared and Raman spectroscopies. Its surface morphologies were characterized by atomic force and scanning electron microscopies. A screen-printed carbon electrode was then modified with the nanocomposite to obtain an enzyme-free glucose sensor. The large surface of fGO and Fe₃O₄ along with the enhanced charge transfer capability of PANI warrant a pronounced electrochemical response (typically measured at 0.18 V versus Ag/AgCl) which is suppressed in the presence of glucose. This reduction of current by glucose was used to design a sensitive method for quantification of glucose. The response of the modified SPCE is linear in the 0.05 μM - 5 mM glucose concentration range, and the lower detection limit is 0.01 μM. Graphical abstract Schematic illustration of in-situ anchoring of Iron oxide on functionalized graphene oxide and synthesis of its polymeric nanocomposite for non-enzymatic detection of Glucose. The nanocomposite modified screen printed interface enabled monitoring of glucose at lower potential with higher precision. GO (graphene oxide), fGO (functionalized graphene oxide), PANI (polyaniline).

One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker

Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications.

N′-[(E)-1-(3-Fluorophenyl)ethylidene]formohydrazide

In the title compound, C₉H₉FN₂O, the dihedral angle between the fluoro­benzene ring and the mean plane of the side chain is 15.59 (14)°. In the crystal, the mol­ecules form inversion dimers linked by pairs of N—H⋯O hydrogen bonds, resulting in R₂²(8) loops. These dimers are reinforced by C—H⋯O inter­actions.

3-Hydr-oxy-N'-[(Z)-(5-methyl-2-fur-yl)methyl-idene]naphthalene-2-carbo-hydrazide

The asymmetric unit of title compound, C₁₇H₁₄N₂O₃, contains three independent mol­ecules. In one of these mol­ecules, the 5-methyl-2-furyl group is disordered over two sets of sites with an occupancy ratio of 0.747 (3):0.253 (3). In the two ordered mol­ecules, the furan and naphthalene rings are oriented at dihedral angles of 11.05 (12) and 32.2 (5)°. In the disordered mol­ecule, the furan rings with major and minor occupancies are oriented at dihedral angles of 41.4 (2) and 26.6 (13)°, respectively, with the corresponding naphthalene ring. An intra­molecular O—H⋯O hydrogen bond occurs within each mol­ecule. In the crystal, mol­ecules are linked by N—H⋯O, N—H⋯(N,O) and C—H⋯O inter­actions.

N'-[(E)-(5-Methyl-furan-2-yl)methyl-idene]formohydrazide

The title compound, C₇H₈N₂O₂, is almost planar (r.m.s. deviation for non-H atoms = 0.029 Å). In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate an R₂²(8) ring motif.

N'-[(1E)-1-(4-Chloro-phen-yl)ethyl-idene]formohydrazide

The structure of the title compound, C₉H₉ClN₂O, consists of centrosymmetric dimers due to inter­molecular N—H⋯O hydrogen bonding, forming R₂²(8) ring motifs. The dihedral angle between the p-chloro­phenyl unit and the remaining heavy-atom group is 6.77 (17)°.

Mirizzi syndrome--a report of 3 cases with a review of the present classifications

We report three cases of Mirizzi syndrome, two with external compression of the common hepatic duct and another with cystobiliary fistula. All patients presented with jaundice. The diagnosis was suggested by ultrasonography and confirmed by endoscopic retrograde cholangiography (ERC). All three had the stones removed surgically, one through a choledochotomy, another through an opening in the gall bladder and the third at the time of subtotal cholecystectomy. We would like to propose a simple classification of Mirizzi syndrome, based on surgical procedures necessary for the correction of the pathological anatomy. If it involves the removal of calculi with some form of cholecystectomy, we consider it as Type I, whereas Type II involves the construction of a hepaticojejunostomy apart from the removal of calculi.