Chitosan lecithin nanocomposite based electrochemical biosensor for glycine detection in biological matrices.

Increased glycine concentrations are associated with altered metabolism of cancer cells and is reflected in the bodily fluids of the brain cancer patients. Various studies have been conducted in past to detect glycine as an imaging biomarker via NMR Spectroscopy tools. However, the use is limited because of the low concentration and different in vivo detection due to overlapping of peaks with myo-inositol in same spectral position. Alongside, little is known about the electrochemical potential of Glycine as a biomarker for brain cancer. The prime impetus of this study was to check the feasibility of glycine as non-invasive biomarker for brain cancer. A divergent approach to detect glycine "non-enzymatically" via unique chitosan lecithin nanocomposite has been utilised during this study. The electrochemical inactivity at provided potential that prevented glycine to get oxidized or reduced without mediator was compensated utilising the chitosan-lecithin nanocomposite. Thus, a redox mediator (Prussian blue) was used for high sensitivity and indirect detection of glycine. The chitosan nanoparticles-lecithin nanocomposite is used as a matrix. The electrochemical analysis of the onco-metabolomic biomarker (glycine) utilizing cyclic voltammetry in glycine spiked multi-Purpose artificial urine was performed to check distribution of glycine over physiological range of glycine. A wide linear range of response varying over the physiological range from 7 to 240 µM with a LOD 8.5 µM was obtained, showing potential of detection in biological samples. We have further evaluated our results via simulating the interaction of mediator and matrix with Glycine by HOMO-LUMO band fluctuations.

Ultralight crystalline hybrid composite material for highly efficient sequestration of radioiodine.

Considering the importance of sustainable nuclear energy, effective management of radioactive nuclear waste, such as sequestration of radioiodine has inflicted a significant research attention in recent years. Despite the fact that materials have been reported for the adsorption of iodine, development of effective adsorbent with significantly improved segregation properties for widespread practical applications still remain exceedingly difficult due to lack of proper design strategies. Herein, utilizing unique hybridization synthetic strategy, a composite crystalline aerogel material has been fabricated by covalent stepping of an amino-functionalized stable cationic discrete metal-organic polyhedra with dual-pore containing imine-functionalized covalent organic framework. The ultralight hybrid composite exhibits large surface area with hierarchical macro-micro porosity and multifunctional binding sites, which collectively interact with iodine. The developed nano-adsorbent demonstrate ultrahigh vapor and aqueous-phase iodine adsorption capacities of 9.98 g.g-1 and 4.74 g.g-1, respectively, in static conditions with fast adsorption kinetics, high retention efficiency, reusability and recovery.

Nanotrap Grafted Anionic MOF for Superior Uranium Extraction from Seawater.

On-demand uranium extraction from seawater (UES) can mitigate growing sustainable energy needs, while high salinity and low concentration hinder its recovery. A novel anionic metal-organic framework (iMOF-1A) is demonstrated adorned with rare Lewis basic pyrazinic sites as uranyl-specific nanotrap serving as robust ion exchange material for selective uranium extraction, rendering its intrinsic ionic characteristics to minimize leaching. Ionic adsorbents sequestrate 99.8% of the uranium in 120 mins (from 20,000 ppb to 24 ppb) and adsorb large amounts of 1336.8 mg g-1 and 625.6 mg g-1 from uranium-spiked deionized water and artificial seawater, respectively, with high distribution coefficient, Kd U ≥ 0.97 × 106  mL g-1 . The material offers a very high enrichment index of ≈5754 and it achieves the UES standard of 6.0 mg g-1 in 16 days, and harvests 9.42 mg g-1 in 30 days from natural seawater. Isothermal titration calorimetry (ITC) studies quantify thermodynamic parameters, previously uncharted in uranium sorption experiments. Infrared nearfield nanospectroscopy (nano-FTIR) and tip-force microscopy (TFM) enable chemical and mechanical elucidation of host-guest interaction at atomic level in sub-micron crystals revealing extant capture events throughout the crystal rather than surface solely. Comprehensive experimentally guided computational studies reveal ultrahigh-selectivity for uranium from seawater, marking mechanistic insight.

A Xanthan-Gum-Stabilized PEG-Conjugated Nanocurcumin Complex: Telescoping Synthesis for Enhanced Permeation Potential.

We report a facile room temperature telescoping synthesis of a nanocurcumin complex with 17.5-fold permeation enhancement as determined by comparative in vitro permeation study with raw curcumin. The permeation results were further validated with in silico drug absorption prediction using ADMET predictors.

Ordered Macro/Microporous Ionic Organic Framework for Efficient Separation of Toxic Pollutants from Water.

In case of pollutant segregation, fast mass diffusion is a fundamental criterion in order to achieve improved performance. The rapid mass transport through porous materials can be achieved by availing large open pores followed by easy and complete accessibility of functional sites. Inducing macroporosity into such materials could serve as ideal solution providing access to large macropores that offer unhindered transport of analyte and full exposure to interactive sites. Moreover, the challenge to configure the ionic-functionality with macroporosity could emerge as an unparalleled avenue toward pollutants separation. Herein, we strategized a synthetic protocol for construction of a positively charged hierarchically-porous ordered interconnected macro-structure of organic framework where the size and number of macropores can easily be tuned. The ordered macropores with strong electrostatic interaction synergistically exhibited ultrafast removal efficiency towards various toxic pollutants.

Hydroxy-Functionalized Hypercrosslinked Polymers (HCPs) as Dual Phase Radioactive Iodine Scavengers: Synergy of Porosity and Functionality.

Large-scale nuclear power plant production of iodine radionuclides (129 I, 131 I) pose huge threat in the events of nuclear disaster. Effective removal of radioiodine from nuclear waste is one of the most critical challenge because of the drawbacks of state-of-the-art adsorbents such as high cost, low uptake capacity and non-recyclability. Herein, two hydroxy-functionalized (-OH) hypercrosslinked polymers (HCPs), namely HCP-91 and HCP-92, have been synthesized and employed towards capture of iodine. High chemical stability along with synergistic harmony of high porosity and functionality of these materials makes them suitable candidates for capture of iodine from both vapor phase and water medium. Moreover, both the HCPs showed superior iodine removal performance from water in terms of fast kinetics and high removal efficiency (2.9 g g-1 and 2.49 g g-1 for HCP-91 and HCP-92 respectively). The role of functionality (-OH groups) and porosity has been established with the help of HCP-91, HCP-92 and non-functionalized biphenyl HCP for the efficient capture of I3 - ions from water. In addition, both HCPs exhibited excellent selectivity and recyclability towards triiodide ions, rendering the potential of these materials towards real-time applications. Lastly, Density functional theoretical studies revealed key insights and corroborate well with the experimental findings.

Strain assisted magnetoelectric coupling in ordered nanomagnets of CoFe2O4/SrRuO3/(Pb(Mg1/3Nb2/3)O3-PbTiO3) heterostructures.

We have explored the electric field controlled magnetization in the nanodot CoFe2O4/SrRuO3/PMN-PT (CFO/SRO/PMN-PT) heterostructures. Ordered ferromagnetic CFO nanodots (∼300 nm lateral dimension) are developed on the PMN-PT substrate (ferroelectric as well as piezoelectric) using a nanostencil-mask pattering method during pulsed laser deposition. The nanostructures reveal electric field induced magnetization reversal in the single domain CFO nanodots through transfer of piezostrains from the piezoelectric PMN-PT substrate to the CFO. Further, electric field modulated spin structure of CFO nanomagnets is analyzed by using x-ray magnetic circular dichroism (XMCD). The XMCD analysis reveals cations (Fe3+/Co2+) redistribution on the octahedral and tetrahedral site in the electric field poled CFO nanodots, establishing the strain induced magneto-electric coupling effects. The CFO/SRO/PMN-PT nanodots structure demonstrate multilevel switching of ME coupling coefficient (α) by applying selective positive and negative electric fields in a non-volatile manner. The retention of two stable states ofαis illustrated for ∼106seconds, which can be employed to store the digital data in non-volatile memory devices. Thus the voltage controlled magnetization in the nanodot structures leads a path towards the invention of energy efficient high-density memory devices.

Unveiling the Impact of Diverse Morphology of Ionic Porous Organic Polymers with Mechanistic Insight on the Ultrafast and Selective Removal of Toxic Pollutants from Water.

In recent years, detoxification of contaminated water by different types of materials has received a great deal of attention. However, lack of methodical in-depth understanding of the role of various physical properties of such materials toward improved sorption performance limits their applicable efficiencies. In perspective, decontamination of oxoanion-polluted water by porous materials with different morphologies are unexplored due to a shortfall of proper synthetic strategies. Herein, systematic optimization of sequestration performance toward efficient decontamination of toxic oxoanion-polluted water has been demonstrated by varying the morphologies of an imidazolium-based cationic polymeric network [ionic porous organic polymers (iPOP-5)]. Detailed morphological evolution showed that the chemically stable ionic polymer exhibited several morphologies such as spherical, nanotube, and flakes. Among them, the flakelike material [iPOP-5(F)] showed ultrafast capture efficiency (up to ∼99 and >85% removal within less than 1 min) with high saturation capacities (301 and 610 mg g-1) toward chromate [Cr(VI)] and perrhenate [Re(VII)] oxoanions, respectively, in water. On the other hand, the spherical-shaped polymer [iPOP-5(S)] exhibited relatively slow removal kinetics (>5 min for complete removal) toward both Cr(VI) and Re(VII) oxoanions. Notably, iPOP-5(F) eliminated Cr(VI) and Re(VII) selectively even in the presence of excessive (∼100-fold) competing anions from both high- and low-concentration contaminated water. Further, the compound demonstrated efficient separation of those oxoanions in a wide pH range as well as in various water systems (such as potable, lake, river, sea, and tannery water) with superior regeneration ability. Moreover, as a proof of concept, a column exchange-based water treatment experiment by iPOP-5(F) has been performed to reduce the concentration of Cr(VI) and Re(VII) below the WHO permitted level. Mechanistic investigation suggested that the rare in situ exfoliation of flakes into thin nanosheets helps to achieve ultrafast capture efficiency. In addition, detailed theoretical binding energy calculations were executed in order to understand such rapid, selective binding of chromate and perrhenate oxoanions with iPOP-5(F) over other nonmetal-based anions.

Trap Inlaid Cationic Hybrid Composite Material for Efficient Segregation of Toxic Chemicals from Water.

Metal-based oxoanions are potentially toxic pollutants that can cause serious water pollution. Therefore, the segregation of such species has recently received significant research attention. Even though several adsorbents have been employed for effective management of chemicals, their limited microporous nature along with non-monolithic applicability has thwarted their large-scale real-time application. Herein, we developed a unique anion exchangeable hybrid composite aerogel material (IPcomp-6), integrating a stable cationic metal-organic polyhedron with a hierarchically porous metal-organic gel. The composite scavenger demonstrated a highly selective and very fast segregation efficiency for various hazardous oxoanions such as, HAsO42- , SeO42- , ReO4- , CrO42- , MnO4- , in water, in the presence of 100-fold excess of other coexisting anions. The material was able to selectively eliminate trace HAsO42- even at low concentration to well below the AsV limit in drinking water defined by WHO.

Unfolding the Role of Building Units of MOFs with Mechanistic Insight Towards Selective Metal Ions Detection in Water.

The potential emergence of fluorescence-based techniques has propelled research towards developing probes that can sense trace metal ions specifically. Although luminescent metal-organic frameworks (MOFs) are well suited for this application, the role of building blocks towards detection is not fully understood. In this work, a systematic screening by varying number of Lewis basic (pyridyl-N atoms) sites is carried out in a series of isostructural, robust UiO-67 MOFs, and targeting a model metal ion-Fe3+ . All the three fluorescent MOFs are seen to present quenching response towards Fe3+ ions in water. However, UiO-67@N exhibits highly selective and sensitive response, whereas emission of both UiO-67 and UiO-67@NN is quenched by several metal ions. Detailed experimental and theoretical mechanistic investigation is carried out in addition to demonstration of UiO-67@N being able to sense trace amount of Fe3+ ions in synthetic biological water sample. Further, UiO-67@N based mixed-matrix membrane (MMM) has been prepared and employed to mimic the real time Fe3+ ions detection in water.

Functionalized Ionic Porous Organic Polymers Exhibiting High Iodine Uptake from Both the Vapor and Aqueous Medium.

Large-scale generation of radioactive iodine (129I, 131I) in nuclear power plants pose a critical threat in the event of fallout, thus rendering the development of iodine sequestering materials (from both the vapor and aqueous medium) highly pivotal. Herein, we report two chemically stable ionic polymers containing multiple binding sites, including phenyl rings, imidazolium cations, and bromide anions, which in synergy promote adsorption of iodine/triiodide anions. In brief, exceptional iodine uptake (from the vapor phase) was observed at nuclear fuel reprocessing conditions. Furthermore, the ionic nature propelled removal of >99% of I3- from water within 30 min. Additionally, benchmark uptake capacities, as well as unprecedented selectivity, were observed for I3-anions. The excellent affinity (distribution coefficient, ∼105 mL/g) enabled iodine capture from seawater-spiked samples. Moreover, iodine-loaded compounds showed conductivity (10-4 S/cm, 10-6 S/cm), placing them among the best known conducting porous organic polymers. Lastly, DFT studies unveiled key insights in coherence with the experimental findings.

Imidazolium-Functionalized Chemically Robust Ionic Porous Organic Polymers (iPOPs) toward Toxic Oxo-Pollutants Capture from Water.

Fabricating new and efficient materials aimed at containment of water contamination, in particular removing toxic heavy metal based oxo-anions (e. g. CrO4 2- , TcO4 - ) holds paramount importance. In this work, we report two new highly stable imidazolium based ionic porous organic polymers (iPOPs) decorated with multiple interaction sites along with electrostatics driven adsorptive removal of such oxo-anions from water. Both the iPOPs (namely, iPOP-3 and iPOP-4) exhibited rapid sieving kinetics and very high saturation uptake capacity for CrO4 2- anions (170 and 141 mg g-1 for iPOP-3 and iPOP-4 respectively) and ReO4 - (515.5 and 350.3 mg g-1 for iPOP-3 and iPOP-4 respectively), where ReO4 - anions being the non-radioactive surrogative counterpart of radioactive TcO4 - ions. Noticeably, both iPOPs showed exceptional selectivity towards CrO4 2- and ReO4 - even in presence of several other concurrent anions such as Br- , Cl- , SO4 2- , NO3 - etc. The theoretical binding energy calculations via DFT method further confirmed the preferential interaction sites as well as binding energies of both iPOPs towards CrO4 2- and ReO4 - over all other competing anions which corroborates with the experimental high capacity and selectivity of iPOPs toward such oxo-anions.

A luminescent cationic MOF for bimodal recognition of chromium and arsenic based oxo-anions in water.

Water pollution from heavy metals and their toxic oxo-anionic derivatives such as CrO42-, Cr2O72-, HAsO42-, and HAsO32- has become one of the most critical environmental issues. To address this, herein, we report a new hydrolytically stable luminescent Zn(ii) based cationic metal organic framework (MOF), iMOF-4C, which further successfully exhibited a rare dual "turn off/on" fluorescence response toward Cr(vi), As(v) and As(iii) based oxo-anions respectively in water medium. In addition, iMOF-4C was found to maintain its superior selectivity in the presence of other concurrent anions (e.g. SO42-, Cl-, Br-, ClO4-, NO3-, SCN- and CO32-). More importantly, iMOF-4C exhibited an excellent selective and sensitive luminescence "turn-off" response towards CrO42- and Cr2O72- anions in water medium with the quenching constant (Ksv) values as high as 1.31 × 105 M-1 (CrO42-) and 4.85 × 105 M-1 (Cr2O72-), which are found to be the highest among the values reported in the regime of MOFs. Interestingly, iMOF-4C showed fluorescence "turn-on" response toward HAsO42- and HAsO32- with an enhancement coefficient (Kec) of 1.98 × 104 M-1 and 3.56 × 103 M-1 respectively. The high sensitivity and low detection limits make iMOF-4C more feasible for real-time sensing of such toxic oxo-anions in an aqueous medium. Furthermore, the probable sensing mechanism has been investigated by DFT calculation studies and discussed in detail.

CuO/ZnO Heterojunction Nanorod Arrays Prepared by Photochemical Method with Improved UV Detecting Performance.

CuO/ZnO heterojunction nanorod arrays were synthesized using a facile photochemical deposition strategy. The morphology of CuO was related to the concentration of Cu2+ in the Cu(NO3)2 solution, UV illumination time, and the air annealing temperature. A possible reaction mechanism was proposed. In the photochemical deposition process, the OH- was generated in the vicinity of the ZnO nanorod arrays and reacted with Cu2+ and NO3- in the solution to form Cu2(NO3)(OH)3/ZnO heterojunction nanorod arrays firstly, which were converted into CuO/ZnO heterojunction nanorod arrays completely after air annealing at a low temperature. The fabricated CuO/ZnO heterojunction nanorod arrays exhibits a well-defined rectifying characteristic and an improved photo-response performance compared with pure ZnO nanorod arrays.

Nanoscale LuFeO3: shape dependent ortho/hexa-phase constitution and nanogenerator application.

In multiferroic LuFeO3 the hexagonal (-h) phase is an intermediate metastable phase encountered during the amorphous to orthorhombic (-o) transformation and is ferroelectric in nature. Thus far it has only been stabilized in a substrate-supported few layered ultrathin film form. Herein we show that the surface-induced strain field intrinsically present in nano-systems can self-stabilize this phase and the hexagonal to orthorhombic phase constitution ratio depends on the shape of the nanomaterial. Thus, nanoparticles (nanofibres) strain-stabilize the o : h ratio of about 75 : 25 (23 : 77). The inclusion of nano-LuFeO3 into PDMS renders impressive nanogenerator performance, consistent with the ferroelectric phase content.

Self-Assembled, Fluorine-Rich Porous Organic Polymers: A Class of Mechanically Stiff and Hydrophobic Materials.

Fluorous organic building blocks were utilized to develop two self-assembled, hydrophobic, fluorinated porous organic polymers (FPOPs), namely, FPOP-100 and FPOP-101. Comprehensive mechanical analyses of these functionalised triazine network polymers marked the introduction of mechanical stiffness among all porous organic network materials; the recorded stiffnesses are analogous to those of their organic-inorganic hybrid polymer congeners, that is, metal-organic frameworks. Furthermore, this study introduces a new paradigm for the simultaneous installation of mechanical stiffness and high surface hydrophobicity into polymeric organic networks, with the potential for transfer among all porous solids. Control experiments with non-fluorinated congeners underlined the key role of fluorine, in particular, bis-trifluoromethyl functionalization in realizing the dual features of mechanical stiffness and superhydrophobicity.

Controlling the ferroelectric and resistive switching properties of a BiFeO3 thin film prepared using sub-5 nm dimension nanoparticles.

In recent years, BiFeO3 has attracted significant attention as an interesting multiferroic material in the exploration of fundamental science and development of novel applications. Our previous study (Phys. Chem. Chem. Phys.18, 2016, 25409) highlighted the interesting physicochemical features of BiFeO3 of sub-5 nm dimension. The study also accentuated the existence of weak ferroelectricity at sub-5 nm dimensions in BiFeO3. Based on this feature, we have prepared thin films using sub-5 nm BiFeO3 nanoparticles and explored various physicochemical properties of the thin film. We report that during the formation of the thin film, the nanoparticles aggregated; particularly, annihilation of their nanotwinning nature was observed. Qualitatively, the Gibbs free energy change ΔG governed the abovementioned processes. The thin film exhibited an R3c phase and enhanced Bi-O-Fe coordination as compared to the sub-5 nm nanoparticles. Raman spectroscopy under the influence of a magnetic field shows a magnetoelectric effect, spin phonon coupling, and magnetic anisotropy. We report room-temperature ferroelectric behavior in the thin film, which enhances with the application of a magnetic field; this confirms the multiferroic nature of the thin film. The thin film shows polarization switching ability at multiple voltages and read-write operation at low bias (±0.5 V). Furthermore, the thin film shows negative differential-complementary resistive switching behavior in the nano-microampere current range. We report nearly stable 1-bit operation for 102 cycles, 105 voltage pulses, and 105 s, demonstrating the paradigm device applications. The observed results thus show that the thin films prepared using sub-5 nm BiFeO3 nanoparticles are a promising candidate for future spintronics and memory applications. The reported approach can also be pertinent to explore the physicochemical properties and develop potential applications of several other nanoparticles.

Observation of nanotwinning and room temperature ferromagnetism in sub-5 nm BiFeO3 nanoparticles: a combined experimental and theoretical study.

Particle size significantly affects the properties and therefore the potential applications of multiferroics. However, is there special particle size effect in BiFeO3, which has a spiral modulated spin structure? This is still under investigation for sub-5 nm BiFeO3. In this report, the structural, electronic and magnetic properties are investigated for chemically synthesized BiFeO3 nanoparticles with an average size of 3 nm. We observed nanotwinning features in the specific size regime of the nanoparticles (2-4 nm). A weak Bi-O-Fe coordination and weak covalent nature has been observed in the nanoparticles through high-resolution electron energy loss spectroscopy and theoretical analysis, confirming that BiFeO3 nanoparticles a retain rudimentary R3c phase even at sub-5 nm dimensions. The R3c phase of sub-5 nm BiFeO3 nanoparticles has also been confirmed using Raman spectroscopy and Raman mapping of the vibrational modes. The nanoparticles display cluster spin glass, room temperature ferromagnetism, and a metamictization-davidite phase. The observation of weak magnetic entropy features confirmed the presence of a weak correlation between the magnetic and ferroelectric components. To support our experimental observations, we have simulated a sub-5 nm BiFeO3 nanocluster. Using density functional theory, the ferromagnetic ground state and the presence of a weak covalent nature in the nanocluster is established considering the first Brillouin zone, thus confirming our experimental results. Finding of new physicochemical features in sub-5 nm BiFeO3 would be beneficial for the understanding of the fundamental physical and chemical science as well as potential device development.

High hydroxide conductivity in a chemically stable crystalline metal-organic framework containing a water-hydroxide supramolecular chain.

A chemically stable cationic MOF encapsulating an in situ formed water-hydroxide supramolecular anionic chain is realized for high hydroxide (OH(-)) ion conductivity in the solid-state (Type A). High OH(-) ion conductivity and low activation energy of the MOF demonstrate the advantage of the in situ incorporation of OH(-) ions to achieve efficient OH(-) ion conduction in the solid-state.