MoS42− intercalated NiFeTi LDH as an efficient and selective adsorbent for elimination of heavy metals

The enormous increase of heavy metal pollution has led to a rise in demand for synthesizing efficient and stable adsorbents for its treatment. Therefore, we have designed a novel adsorbent by introducing (MoS₄)²⁻ moieties within the layers of NiFeTi LDH-NO₃, via an ion exchange mechanism, as a stable and efficient adsorbent to deal with the increasing water pollution due to heavy metals. Characterization techniques such as XRD, FTIR, TGA, SEM, TEM, and Raman spectroscopy were used to confirm the formation of (MoS₄)²⁻ intercalated NiFeTi LDH and structural changes after the adsorption process. The efficiency of the material was tested with six heavy metal ions, among which it was found to be effective for toxic Pb²⁺ and Ag⁺ ions. When selectivity was studied with all six of the metal ions copresent in one solution, the material showed greater selectivity for Pb²⁺ and Ag⁺ ions with the selectivity order of Ni²⁺ < Cu²⁺ < Zn²⁺ < Fe³⁺ < Pb²⁺ < Ag⁺, with great adsorption capacities of 653 mg g⁻¹ for Pb²⁺ and 856 mg g⁻¹ for Ag⁺ metal ions. Further, the kinetics adsorption study for both the metal ions had a great correlation with the pseudo-second-order model and supported the chemisorption process via the formation of M–S bonding. The adsorption process obeyed the Langmuir model. Therefore, the MoS₄-LDH material could be a promising adsorbent for the removal of heavy metals.

Elimination of the heavy metals by using the MoS₄-LDH adsorbent.     

A novel water-soluble naked-eye probe with a large Stokes shift for selective optical sensing of Hg2+ and its application in water samples and living cells

A water-soluble and colorimetric fluorescent probe with a large Stokes shift (139 nm) for rapidly detecting Hg²⁺, namely Hcy-mP, was synthesized by using an indole derivative and 2,4-dihydroxybenzaldehyde as starting materials. This probe demonstrates good selectivity for Hg²⁺ over other metal ions including Ag⁺, Pb²⁺, Cd²⁺, Cr³⁺, Zn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, K⁺, Na⁺, Mg²⁺, and Ca²⁺ in aqueous solution. With the increase in concentration of Hg²⁺, the color of the solution changed from pale yellow to pink and the fluorescence intensity decreased slightly. When 5-equivalents of EDTA were added to the solution with Hg²⁺, the fluorescence intensity of this probe was restored. The probe has been applied to the detection of Hg²⁺ in real water samples. Moreover, this probe was confirmed to have low cytotoxicity and excellent cell membrane permeability. The effect of Hcy-mP–Hg²⁺ towards living cells by confocal fluorescence was also investigated.

A water-soluble and colorimetric fluorescent probe with a large Stokes shift (139 nm) for rapidly detecting Hg²⁺, namely Hcy-mP, was synthesized by using an indole derivative and 2,4-dihydroxybenzaldehyde as starting materials.     

Super rapid removal of copper,cadmium and lead ions from water by NTA-silica gel

Copper (Cu²⁺), cadmium (Cd²⁺) and lead ions (Pb²⁺) are toxic to human beings and other organisms. In this study, a silica gel material modified with nitrilotriacetic acid (NTA-silica gel) was sensibly designed and prepared via a simple amidation procedure for the removal of Cu²⁺, Cd²⁺ and Pb²⁺ from water. The NTA-silica gels showed rapid removal performances for the three metal ions (Pb²⁺ (<2 min), Cu²⁺ and Cd²⁺ (<20 min)) with relatively high adsorption capacities (63.5, 53.14 and 76.22 mg g⁻¹ for Cu²⁺, Cd²⁺ and Pb²⁺, respectively). At the same concentration of 20 mg L⁻¹, the removal efficiencies of the three metals by the adsorbent ranged from 96% to 99%. The Freundlich and Langmuir models were utilized to fit the adsorption isotherms. The adsorption kinetics for the three metal ions was pseudo-second-order kinetics. The removal performance of the NTA-silica gels increased in a wide pH range (2–9) and maintained in the presence of competitive metal ions (Na⁺, Mg²⁺, Ca²⁺ and Al³⁺) with different concentrations. In addition, the NTA-silica gels were easily regenerated (washed with 1% HNO₃) and reused for 5 cycles with high adsorption capacity. This study indicates that the NTA-silica gel is a reusable adsorbent for the rapid, convenient, and efficient removal of Cu²⁺, Cd²⁺, and Pb²⁺ from contaminated aquatic environments.

A silica gel material modified with nitrilotriacetic acid (NTA-silica gel) was sensibly designed and prepared via a simple method for the super rapid removal of Cu²⁺, Cd²⁺ and Pb²⁺ from water.     

Synthesis and spectroscopic investigation of a novel sensitive and selective fluorescent chemosensor for Ag+ based on a BINOL–glucose derivative

Based on a versatile 2,2′-binaphthol (BINOL) backbone, a novel BINOL–glucose derivative fluorescent sensor was synthesized using a click reaction. The fluorescence responses of the BINOL–glucose derivative (S,β-d)-1 conclude that it can be used as a specific fluorescent chemical sensor for Ag⁺ in the presence of a large number of competing metal ions without any obvious interference from other metal ions. Mass spectrometric and NMR spectroscopic data were used to study the mechanism, and implied the formation of a 1 + 1 complex between BINOL–glucose 1 and Ag⁺. Both the oxygen atoms of S-BINOL and two nitrogen atoms of triazole were involved in coordinating the silver ion.

A BINOL–glucose derivative fluorescent sensor was synthesized to detect only Ag⁺ with high selectivity and sensitivity in a 1 + 1 formation.     

Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

Silver in its ionic form (Ag⁺), but not the bulk metal (Ag⁰), is toxic to microbial life forms and has been used for many years in the treatment of wound infections. The prevalence of bacterial resistance to silver is considered low due to the nonspecific nature of its toxicity. However, the recent increased use of silver as an antimicrobial agent for medical, consumer, and industrial products has raised concern that widespread silver resistance may emerge. Pseudomonas aeruginosa is a common pathogen that produces pyocyanin, a redox toxin and a reductant for molecular oxygen and ferric (Fe³⁺) ions. The objective of this study was to determine whether pyocyanin reduces Ag⁺ to Ag⁰, which may contribute to silver resistance due to lower bioavailability of the cation. Using surface plasmon resonance spectroscopy and scanning electron microscopy, pyocyanin was confirmed to be a reductant for Ag⁺, forming Ag⁰ nanoparticles and reducing the bioavailability of free Ag⁺ by >95% within minutes. Similarly, a pyocyanin-producing strain of P. aeruginosa (PA14) reduced Ag⁺ but not a pyocyanin-deficient (ΔphzM) strain of the bacterium. Challenge of each strain with Ag⁺ (as AgNO₃) gave MICs of 20 and 5 μg/ml for the PA14 and ΔphzM strains, respectively. Removal of pyocyanin from the medium strain PA14 was grown in or its addition to the medium that ΔphzM mutant was grown in gave MICs of 5 and 20 μg/ml, respectively. Clinical isolates demonstrated similar pyocyanin-dependent resistance to Ag⁺. We conclude that pseudomonal silver resistance exists independently of previously recognized intracellular mechanisms and may be more prevalent than previously considered.     

Functionalization of silver nanoparticles with mPEGylated luteolin for selective visual detection of Hg2+ in water sample

A novel colorimetric sensor based on mPEGylated luteolin-functionalized silver nanoparticles (mPEGylated luteolin-AgNPs) in an aqueous solution was prepared. The mPEGylated luteolin-AgNP solution was utilized to detect Hg²⁺ with high sensitivity and selectivity in the presence of other metal cations including Na⁺, K⁺, Mg²⁺, Zn²⁺, Ni²⁺, Mn²⁺, Ba²⁺, Pb²⁺, Sr²⁺, Ca²⁺, Cd²⁺, Al³⁺ and Cu²⁺. The solution could be induced to aggregate, and a color change from yellow-brown to colorless was observed in the presence of Hg²⁺. Meanwhile, the sensor was successfully used to detect Hg²⁺ in tap water with satisfactory recovery ranges using the standard addition method.

A novel colorimetric sensor for selective detection of Hg²⁺ based on mPEGylated luteolin functionalized silver nanoparticles was prepared.     

Electrochemical heavy metal removal from water using PVC waste-derived N,S co-doped carbon materials

The removal of heavy metal contaminants has aroused global attention due to water shortage and the lax control on the discharge of heavy metal pollutants. Capacitive deionization (CDI) has emerged as a robust, energy-/cost-efficient technique for water treatment. Herein, we reported the simple synthesis of N, S-co-doped carbon materials (NS-C) derived from PVC plastic wastes as CDI electrode materials for the efficient removal of heavy metal ions (HMIs). The NS-C exhibited a large specific surface area (∼1230 m² g⁻¹) and contained heavy heteroatom doping (∼4.55 at% N and ∼13.30 at% S). The CDI electrode fabricated using NS-C showed high removal efficiency (94–99%), high capacity (36–62 mg g⁻¹), and good regeneration capability for the adsorption of various kinds of low-concentration heavy metal ions (including Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Pb²⁺, and Cd²⁺). Moreover, PVC plastic wastes that are heavily accumulated in the environment and extremely hard to be decomposed and recycled were applied as the carbon source in this study for the fabrication of NS-C, which further rendered the importance of our study in practically treating hazardous waste (HMIs) with waste (PVC plastic wastes) in a clean and efficient way.

N, S-codoped carbon materials derived from PVC plastic wastes were used for electrochemically removing heavy metal pollutants from water.     

Bis-BODIPY linked-triazole based on catechol core for selective dual detection of Ag+ and Hg2+

Herein, we introduced a new chemosensor, bis-BODIPY linked-triazole based on catechol (BODIPY-OO) prepared by bridging two units of BODIPY fluorophore/triazole binding group with a catechol unit. A solution of this compound displayed 4- and 2-fold enhancements in fluorescence intensity after adding a mole equivalent amount of Ag⁺ and Hg²⁺ ions in methanol media, respectively. ¹H NMR titrations of BODIPY-OO with Ag⁺ and Hg²⁺ suggested that the triazole was involved in the recognition process. BODIPY-OO showed high sensitivity toward Ag⁺ and Hg²⁺ over other metal ions with detection limits of 0.45 μM and 1 μM, respectively. It can also distinguish Hg²⁺ from Ag⁺ by addition of an EDTA. This compound can therefore be employed as practical fluorescent probe for monitoring the presence of Ag⁺ and Hg²⁺ ions.

BODIPY–triazole–catechol combination serves as a “turn-on” fluorescent probe for dual detection and differentiation of Hg²⁺ and Ag⁺ ions.     

Factors governing the competition between group IA and IB cations for monensin A: a DFT/PCM study

The affinity of monensin A to bind monovalent metal cations was evaluated by means of density functional theory (DFT) combined with polarizable continuum model (PCM) computations. The effect of various factors on complex formation between the monensinate A anion and group IA and IB metal ions was assessed. Competition between Na⁺ taken as a reference and monovalent metal cations was estimated using the Gibbs free energy for substituting the ligand-bound Na⁺ with its rival ions in the process [M⁺-solution] + [Mon⁻Na⁺] → [Mon⁻M⁺] + [Na⁺-solution] (M⁺ = Li⁺, K⁺, Rb⁺, Cs⁺, Cu⁺, Ag⁺ and Au⁺). The calculations revealed that the decrease in size of the cations accompanied by an increase of their accepting ability enhances the metal selectivity towards ligand donor atoms. In the gas-phase the affinity of monensinate A decreases in the order Cu⁺ > Li⁺ > Na⁺ > Au⁺ > Ag⁺ > K⁺ > Rb⁺ > Cs⁺. The complex formation can be manipulated by changing the solvent used. The polyether ionophore selectively binds Na⁺ ions in polar solvents but could become Li⁺ or Cu⁺-selective in low-polarity solvents.

The results obtained suggest that the metal selectivity of monensin can be modulated by changing the solvents used.     

Photocatalytic dye-degradation activity of nano-crystalline Ti1−xMxO2−δ (M =Ag,Pd, Fe,Ni and x = 0, 0.01) for water pollution abatement

Nanocrystalline metal-ion (M = Fe, Ni, Ag, and Pd) doped and undoped anatase-TiO₂ powders were prepared using a solution combustion method. The photocatalytic degradation of different dyes such as methylene blue (MB), rhodamine B (RB), rhodamine B base (RBB), and thionine acetate (TA) was investigated under UV exposure. The degradation rate of the dyes were found to be better in the case of Ag⁺ and Pd²⁺ doped TiO₂, whereas Fe³⁺ and Ni²⁺ doped TiO₂ showed lower photocatalytic activity compared to undoped TiO₂ nanoparticles. Combustion synthesized catalysts exhibited much better activity compared to the commercial Degussa P25 (75% anatase + 25% rutile) TiO₂ photocatalyst. The intermediate states created in the band gap of the TiO₂ photocatalyst due to doping of first row transition metal ions (such as Fe³⁺ and Ni²⁺) into the TiO₂ lattice act as recombination centres and the electrons present in the d-orbital quench the photogenerated holes by indirect recombination, hence increasing e⁻–h⁺ recombination rates. As a result, a decrease in the photocatalytic activity of TiO₂ doped with first row transition metal ions is observed. However, in the case of noble metal ions (such as Ag⁺ and Pd²⁺) in TiO₂, photoreduction of Ag⁺ and Pd²⁺ ions occurs upon UV irradiation, hence the noble metal-ions act as electron scavengers. Consequently, the lifetime of the holes (h⁺) increases and hence higher photocatalytic oxidation activity of the dyes is observed. A novel strategy of electron scavenging is envisaged here to develop Ag⁺ and Pd²⁺ doped TiO₂ to increase the photocatalytic oxidation of organic dyes for the development of better water pollution abatement catalysts. Redox-pair stabilization in the TiO₂ lattice similar to photo-chromic glasses play a defining role in enhancing the photocatalytic activity of the catalyst and is a key finding for the development of superior photocatalysts. With the help of UV-vis and fluorescence spectroscopy, the mechanisms of the superior oxidation activity of Pd²⁺ and Ag⁺ doped TiO₂ nanoparticles are explained.

Redox-pair stabilization in TiO₂ lattice by doping of Ag⁺ and Pd²⁺ ions play a defining role in enhancing the photocatalytic activity of the catalyst by scavenging electrons generated through UV-irradiation on the catalyst.     

Reduction of silver ions in molybdates: elucidation of framework acidity as the factor controlling charge balance mechanisms in aqueous zinc-ion electrolyte

A percolating network of high electrical conductivity needed to operate electrodes at a fast rate can be formed by in situ reduction of Ag⁺ originating from mixed metal oxide lattices, but few studies have elucidated trends in this mechanism as a function of Ag⁺ concentration and structure. Candidates compared for the first time here are spinel Ag₂MoO₄, monoclinic and triclinic Ag₂Mo₂O₇, and Ag₂Mo₃O₁₀·2H₂O, which have reduction potentials for Ag⁺ and Mo⁶⁺ strongly decoupled by up to ∼600 mV in aqueous zinc-ion electrolyte. Under these conditions, Ag⁰ is the first reduction product and a decrease of charge transfer resistance by ∼100× is observed within 2.5% consumption of total Ag⁺ independent of initial structure. However, resistance metrics alone poorly describe materials which are robust to reducing silver with high energy at faster rates. Instead, after accounting for crystallinity and morphology differences, we find that the acidity of the molybdate framework is responsible for a switch in charge balance mechanism from the bulk formation of a mixed ZnMoO_x to pseudocapacitive Zn²⁺ precipitation, and that this mechanism switch is associated with minimized losses to rate, voltage and capacity yields as carbon/binder free electrodes relative to composites. The location of this acidity cutoff near the pH of the ZnSO₄ electrolyte may suggest a design principle for future low-carbon electrodes beyond molybdate framework structures.

Across four molybdates, reduction of silver ions in aqueous zinc electrolyte is more facile with increasing acidity.     

A highly sensitive and selective fluorescent probe without quencher for detection of Pb2+ ions based on aggregation-caused quenching phenomenon

Lead is a highly toxic heavy metal, and various functional nucleic acid (FNA)-based biosensors have been developed for the detection of Pb²⁺ in environmental monitoring. However, most fluorescence biosensors that have been reported were designed on the basis of a double-labeled (fluorophore and quencher group) DNA sequence, which not only involved an inconvenient organic synthesis but also restricted their wider use in practical applications. Here, we utilized a G-rich DNA sequence as a recognition probe and conjugated fluorene (CF) to develop a fluorescence sensor without a quencher based on the aggregation-caused quenching (ACQ) effect. In the presence of Pb²⁺, the degree of aggregation of CF was reduced because Pb²⁺ induced the formation of a G-quadruplex structure of the CF-DNA probe, and the fluorescence signal increased with the concentration of Pb²⁺ (0–1 μM), with a limit of detection of 0.36 nM. This fluorescent probe without a quencher enables the sensitive and selective detection of Pb²⁺. On the basis of these advantages, the CF-DNA probe represents a promising analytical method for detecting Pb²⁺.

Fluorescent probe with only a fluorophore but no quencher for detecting Pb²⁺ on the basis of the aggregation-caused quenching (ACQ) phenomenon.     

Nanochannel-based sensor for the detection of lead ions in traditional Chinese medicine

Lead ions (Pb²⁺) are used in the quality control of traditional Chinese medicine (TCM) preparations because they are highly toxic to human health. At present, sophisticated analytical instrumentation and complicated procedures for sample analysis are needed for the determination of Pb²⁺. Herein, a simple, fast, and sensitive peptide-modified nanochannel sensor to detect Pb²⁺ in TCM is reported, which is based on a Pb²⁺-specific peptide modified porous anodized aluminum membrane (PAAM). This peptide-based nanochannel clearly has the highest selectivity for Pb²⁺ when compared to other heavy metal ions, including As²⁺, Cd³⁺, Co²⁺, Cr²⁺, Cu²⁺, Fe³⁺, Hg²⁺, Mg²⁺, Mn²⁺, Ni²⁺, and Zn²⁺. Based on linear ranges from 0.01 to 0.16 μM and 10 to 100 μM, the detection limit was calculated to be 0.005 μM. Moreover, this peptide-based nanochannel sensor was successfully used to detect Pb²⁺ in complex TCM samples. In addition, when compared with the gold standard atomic absorption spectrophotometry (AAS) method, the recovery of the peptide-modified nanochannel sensor was between 87.7% and 116.8%. The experimental results prove that this new sensor is able to achieve accurate detection of Pb²⁺ in TCM samples. Thus, this sensor system could provide a simple assay for sensitive and selective detection of Pb²⁺ in TCM, thereby showing great potential in the practical application for the quality control of heavy metals in TCM.

The nanochannel-based sensor is able to achieve detection of Pb²⁺ in TCM samples.     

The use of acrylic yarn modified with amidoxime and carboxylate-containing polymer for lead removal from drinking water

Amidoxime and carboxylate-containing polymer adsorbents derived from acrylic yarn exhibit high adsorption capacity for lead(ii) (Pb²⁺) ions in water. The adsorption process follows pseudo-second-order kinetics and fits the extended Langmuir isotherm model with the maximum adsorption capacity of Pb²⁺ with 238 mg lead per gram of the fiber at room temperature. Endothermic (ΔH° = 20.3 kJ per mole), spontaneous, and with the increase in the entropy of Pb²⁺ adsorption was observed from the thermodynamic studies. Dynamic column adsorption experiments showed that the fiber can process 4.3 L of water spiked with 1 ppm of lead(ii) solution at a flow rate of 4.4 mL per min under the specified conditions. The selectivity of Pb²⁺ with the competitive metal ions showed varying results with highly selective for Pb²⁺ in a binary solution with sodium and calcium and varying degrees of competitiveness with transition metal ions. This efficient and easily prepared fiber adsorbent appears to be a promising new material for the remediation of lead-contaminated aquatic environments and potable waters.

Amidoxime and carboxylate-containing polymer adsorbents derived from acrylic yarn exhibit high adsorption capacity for lead (Pb²⁺) ions in water.     

Metal oxide QD based ultrasensitive microsphere fluorescent sensor for copper,chromium and iron ions in water

Herein we developed a rapid, cheap, and water-soluble ultra-sensitive ZnO quantum dot (QD) based metal sensor for detecting different hazardous metal ions up to the picomolar range in water. Various spectroscopic and microscopic techniques confirmed the formation of 2.15 ± 0.46 μm of ZnO QD conjugated CMC microspheres (ZCM microspheres) which contain 5.5 ± 0.5 nm fluorescent zinc oxide (ZnO) QDs. Our system, as a promising sensor, exhibited excellent photostability and affinity towards various heavy metal ions. The detection limits were calculated to be 16 pM for Cu²⁺ and 0.18 nM for Cr⁶⁺ ions which are better than previously reported values. The simple fluorescence ‘turn off’ property of our ZCM microsphere sensor system can serve a two-in-one purpose by not only detecting the heavy metals but also quantifying them. Nonetheless, pattern recognition for different heavy metals helped us to detect and identify multiple heavy metal ions. Finally, their practical applications on real samples also demonstrated that the ZCM sensor can be effectively utilized for detection of Cr⁶⁺, Fe³⁺, Cu²⁺ present in the real water samples. This study may inspire future research and design of target fluorescent metal oxide QDs with specific functions.

Herein we developed a rapid, cheap, and water-soluble ultra-sensitive ZnO quantum dot (QD) based metal sensor for detecting different hazardous metal ions up to the picomolar range in water.     

Selective determination of Ag+ in the presence of Cd2+, Hg2+ and Cu2+ based on their different interactions with gold nanoclusters

In this work, a fluorescence method was developed for selective detection of Ag⁺ in the presence of Cd²⁺, Hg²⁺, and Cu²⁺ based on gold nanoclusters (AuNCs). That is, bovine serum albumin (BSA) templated AuNCs with double emission peaks were synthesized using BSA as a protective agent. AuNCs with uniform distribution and average size between 2.0 and 2.2 nm were synthesized using a green and simple method, and showed bright orange-red fluorescence under ultraviolet light. AuNCs have two emission peaks at 450 nm and 630 nm with an excitation wavelength of 365 nm. Under alkaline conditions, Cd²⁺ can combine with the surface sulfhydryl groups of BSA–AuNCs to form Cd–S bonds, which cause AuNCs to aggregate, resulting in an increase in fluorescence intensity at 630 nm. Conversely, due to the d¹⁰–d¹⁰ metal affinity interaction, the addition of Hg²⁺ can reduce the fluorescence peak at 630 nm. Ag⁺ was reduced to Ag⁰ by gold nuclei in AuNCs, forming a stable hybrid Au@ AgNCs species with blue-shifted and enhanced fluorescence. Finally, the paramagnetic behavior of Cu²⁺ combined with BSA causes the excited electrons of the gold cluster to lose their energy via ISC, eventually leading to simultaneous quenching of the two emission peaks. The results show that the limit of detection (LOD) of Ag⁺, Hg²⁺, Cd²⁺ and Cu²⁺ is 1.19 μM, 3.39 μM, 1.83 μM and 5.95 μM, respectively.

A fluorescence method was developed for selective detection of Ag⁺ in the presence of Cd²⁺, Hg²⁺, and Cu²⁺ based on gold nanoclusters. The limit of detection for Ag⁺, Hg²⁺, Cd²⁺ and Cu²⁺ is 1.19 μM, 3.39 μM, 1.83 μM and 5.95 μM, respectively.     

Plasmonic nanoprobes based on the shape transition of Au/Ag core–shell nanorods to dumbbells for sensitive Hg-ion detection

We report a sensitive and selective localized surface plasmon resonance (LSPR) nanoprobe for the detection of mercuric ions (Hg²⁺) using gold/silver core–shell nanorods as an optical nanosubstrate. Sulfide can quickly react with silver atoms to generate Ag₂S at room temperature in the presence of oxygen. The transformation from Ag shell to Ag₂S on the nanorod surface results in its LSPR absorption band shifting to a longer wavelength, which is attributed to their different refractive indices. Interestingly, the morphology also changed from a rod-like to dumbbell shape. However, in the presence of Hg²⁺, this morphology transformation is inhibited because the sulfide reacts with free Hg²⁺ prior to the Ag atoms. The amount of Ag₂S reduced with the increasing concentration of Hg²⁺, and the absorption band shift was also decreased. According to this “rod-like to dumbbell or not” shape change, a sensitive and selective LSPR nanoprobe was established, assisted by UV-Vis absorption spectroscopy. The detection limit of this probe for Hg²⁺ was as low as 13 nM. The efficiency of this probe in complex samples was evaluated by the detection of Hg²⁺ in spiked water samples.

Sensitive plasmonic nanoprobes for the sensitive detection of mercury ions based on a “rod-like to dumbbell or not” morphology transition of the Au/Ag core–shell hybrid nanorods.     

Co-assembly of charge complementary peptides and their applications as organic dye/heavy metal ion (Pb2+, Hg2+) absorbents and arsenic(iii/v) detectors

Learning from nature, molecular self-assembly has been used extensively to generate interesting materials using a bottom up approach. The enthusiasm in this field of research stems from the unique properties of these materials and their diverse applications. The field has not been limited to studying assembly of similar types of molecules but extended to multi component systems via the co-assembly phenomenon. We have designed two charge complementary peptides to study their co-assembly in mechanistic detail in the present work. The cooperative self-assembly is mainly driven by electrostatic interaction that is aided by aromatic interactions, hydrogen bonding interactions and hydrophobic interactions. The hydrogels obtained have been employed in waste water remediation. Both the self-assembled and co-assembled hydrogels are capable of removal of different kinds of organic dyes (cationic, anionic and neutral) and toxic metal ions (Ni²⁺, Co²⁺, Pb²⁺ and Hg²⁺) individually and as a mixture from water with high efficiency. Additionally, the peptides developed in this study can act as ion sensors and detect arsenic in its most toxic (III/V) oxidation states. Molecular understanding of the assembly process is of fundamental importance in the rational design of such simple, robust yet economically viable materials with versatile and novel applications.

Self- and co-assembled gels from charge complementary peptides with waste water remediation applications.     

Measurement of selected ions related to oxidative stress and energy metabolism in Saudi autistic children

Objectives:Autism is a developmental disorder characterized by social and emotional deficits, language impairments and stereotyped behaviors that manifest in early postnatal life. This study aims to clarify the role of selected ions related to energy metabolism as a consequence of oxidative stress in the deterioration accompanied autism.Materials and methods:Malonaldehyde as measure of lipid peroxidation, Na⁺/K⁺ ion pump (ATPase), together with the concentrations of Na⁺, K⁺, Mg²⁺, Ca²⁺ and Pb²⁺ were determined in plasma of 30 Saudi autistic patients and compared to 30 age-matching control samples.Results:The obtained data recorded that Saudi autistic patients have a remarkable higher activities of Na⁺/K⁺ ATPase and high levels of lipid peroxidation compared to control. In addition, they have significantly elevated levels of K⁺ and Pb²⁺ while Ca²⁺ recorded a significantly lower level compared to age-matching control subjects. On the other hand both Mg²⁺ and Na⁺ were non-significantly changed in autistic patients.Conclusion:Alteration of the selected measured ions confirms that oxidative stress and defective mitochondrial energy production could represent the primary causative factor in the pathogenesis of autism.