Josefina Pons

Recent Trends in Macro-, Micro-, and Nanomaterial-Based Tools and Strategies for Heavy-Metal Detection

Recent Trends in Macro-, Micro-, and Nanomaterial-Based Tools and Strategies for Heavy-Metal Detection Gemma Aragay, Josefina Pons, and Arben Merkoc-i* Nanobioelectronics & Biosensors Group, Institut Catal a de Nanotecnologia (CIN2, ICN-CSIC), 08193, Bellaterra, Barcelona, Spain Departament of Chemistry, Universitat Aut onoma de Barcelona, 08193, Bellaterra, Barcelona, Spain ICREA, Barcelona, Spain

Multiphoton laser direct writing of two-dimensional silver structures.

We report a novel and efficient method for the laser direct writing of two-dimensional silver structures. Multiphoton absorption of a small fraction of the output of a Ti:sapphire oscillator is sufficient to photoreduce silver nitrate in a thin film of polyvinylpyrrolidone that has been spin-coated on a substrate. The polymer can then be washed away, leaving a pattern consisting of highly interconnected silver nanoparticles. We report the characterization of the silver patterns using scanning electron and atomic force microscopies, and demonstrate the application of this technique in the creation of diffraction gratings.

All-integrated and highly sensitive paper based device with sample treatment platform for Cd2+ immunodetection in drinking/tap waters.

Nowadays, the development of systems, devices, or methods that integrate several process steps into one multifunctional step for clinical, environmental, or industrial purposes constitutes a challenge for many ongoing research projects. Here, we present a new integrated paper based cadmium (Cd(2+)) immunosensing system in lateral flow format, which integrates the sample treatment process with the analyte detection process. The principle of Cd(2+) detection is based on competitive reaction between the cadmium-ethylenediaminetetraacetic acid-bovine serum albumin-gold nanoparticles (Cd-EDTA-BSA-AuNP) conjugate deposited on the conjugation pad strip and the Cd-EDTA complex formed in the analysis sample for the same binding sites of the 2A81G5 monoclonal antibody (mAb), specific to Cd-EDTA but not Cd(2+) free, which is immobilized onto the test line. This platform operates without any sample pretreatment step for Cd(2+) detection thanks to an extra conjugation pad that ensures Cd(2+) complexation with EDTA and interference masking through ovalbumin (OVA). The detection and quantification limits found for the device were 0.1 and 0.4 ppb, respectively, these being the lowest limits reported up to now for metal sensors based on paper. The accuracy of the device was evaluated by addition of known quantities of Cd(2+) to different drinking water samples and subsequent Cd(2+) content analysis. Sample recoveries ranged from 95 to 105% and the coefficient of variation for the intermediate precision assay was less than 10%. In addition, the results obtained here were compared with those obtained with the well-established inductively coupled plasma emission spectroscopy (ICPES) and the analysis of certificate standard samples.

Enhanced electrochemical detection of heavy metals at heated graphite nanoparticle-based screen-printed electrodes

The effect of temperature upon the electrochemical stripping performance of a heavy metal sensor based on carbon nanoparticles is studied. The morphological changes of the sensing surface during the multidetection of Cd2+, Pb2+, Cu2+ and Hg2+ ions are studied by TEM and SEM. The effect of the temperature on the heavy metal deposition using carbon nanoparticle-based SPEs is also compared to a sensor that does not contain carbon nanoparticles. The effect of temperature seems to be more pronounced for the nanoparticle-based sensor. This phenomenon is clarified by the electrochemical response as well as the TEM and SEM images of the sensing materials used. In addition, the response performance of the nanoparticle-based sensors for increasing concentrations of heavy metals from 5–100 μg L−1 for Cd2+, Pb2+ and Cu2+ and from 1 to 10 μg L−1 for Hg2+, in both single and multiple detections with potential for real applications, is presented. The nanoparticle-based sensor seems to be stable for up to one month while being used in continuous monitoring of heavy metals in seawater.

High sensitive gold-nanoparticle based lateral flow Immunodevice for Cd2+ detection in drinking waters

In this work for first time a lateral flow immunosensor device (LFID) for Cd(2+) determination in drinking and tap waters using the Cd-EDTA-BSA-AuNP conjugate as signal producer tool is introduced. The principle of working is based on competitive reaction between the Cd-EDTA-BSA-AuNP conjugate deposited on the conjugation pad strip and the Cd-EDTA complex formed in the analysis sample for the same binding sites of the 2A81G5 monoclonal antibody, specific to Cd-EDTA but not Cd(2+) free, which is immobilized onto the test line. The device has a large response range within 0.4-2000ppb, being the linear response between 0.4 and 10ppb. The quantification and detection limits of 0.4 and 0.1ppb, respectively, represent the lowest ones reported so far for paper based metal sensors. The obtained detection limit is 50 times lower than the maximum contamination level required for drinking water. Here we also show a new option for increasing the sensibility in the LFDs with competitive format, through the decreasing in concentrations of the Cd-EDTA-BSA-AuNP conjugate deposited in the conjugation strip and the mAbs deposited in the test and control zones until to reach optimized concentrations. It is an important result take into account that the increase in sensibility is one of the challenges in the field of LFD sensors, where are focused many of the ongoing researches. In addition, a specificity study of the device for several metal interferences, where potential metal interferences are masked with the use of the EDTA and OVA optimized concentrations, is presented too.

Copper complexes with a pyrazole derivative ligand. Crystal structure of tetrakis{[(3,5-bis(pyridin-2-yl)pyrazolate)-(aqua)copper(II) nitrate monohydrate}

Abstract Reaction of the pyrazole-derived ligand 3,5-bis(pyridin-2-yl)pyrazole (bpypz) with Cu(NO3)2, CuCl2 and CuBr2 yields polynuclear copper(II) compounds with remarkable structural and magnetic properties. The magnetic behaviour was studied by fitting the experimental data with a dimer and tetramer magnetic model. Strong antiferromagnetic exchange interactions were found in all cases. The molecular structure of the nitrate compound was solved by X-ray diffraction methods. The compound is tetranuclear, orthorhombic, space group Fddd, a = 18.572(4), b = 23.816(8), c = 27.337(9) A, V= 12092 A3, Z = 8.

Organometallic rhodium (I) complexes with 1-alkylaminopyrazole ligands

Abstract New bidentate NN ′ and tridentate NN ′ N 1-alkylaminopyrazoles were synthesized and characterized by elemental analyses and spectroscopic methods. The reaction of [RhCl(cod) 2 ] (cod=cycloocta-1,5-diene) with one equivalent of L 1-alkylaminopyrazoles afforded Rh 2 Cl 2 (L)(cod) 2 complexes (L= NN ′ and NN ′ N ). These rhodium (I) compounds were studied by IR, 1 H- and 13 C-NMR and liquid mass (with electrospray and APCI interfaces) spectrometries. The 1 H-NMR spectra and molar conductances of these complexes suggested the presence of 1:1 electrolyte species, [Rh(L)cod] + [RhCl 2 (cod)] − , in solution. A combined electrospray and APCI liquid mass spectroscopy study confirmed the presence of both [Rh(L)cod] + and [RhCl 2 (cod)] − species in solution but the existence of a neutral molecular form of complexes in solution could not be demonstrated.

Dinuclear μ-pyrazole nickel(II), cobalt(II), cadmium(II) and zinc(II) complexes with dinucleating pyrazole-derived ligands

Abstract New pyrazole-derived ligands, 3,5-bis(2-pyridyl)pyrazole (HL), 2-(6-methyl) pyridyl-2-pyridyl-3,5-pyrazole (HL1) and 3,5-bis-2-(6-methyl)pyridyl-3,5-pyrazole (HL2), are reported. Complexes of formulae [ML(NO3)]·xH2O (M = CoII, NiII, ZnII and CdII), [ML(NCS)]·H2O (M = CoII, NiII, ZnII and CdII), [ML1(NO3)]·H2O (M = NiII and CoII), [M2L2(NO3)2(OH)]·H2O (M = NiII and CoII), [M2L1Cl2(OH)] (M = CoII and NiII) were synthesized and characterized by IR and UV-vis spectroscopies and magnetic susceptibility measurements. Dinuclear compounds containing a di-μ-pyrazole bridge are found in nitrate and thiocyanate complexes with the first two ligands, while mixed μ-hydroxo, μ-pyrazole-bridged structures are found in chloride complexes with the second ligand and nitrate complexes with the last ligand.

Reaction of platinum(II) derivatives with 1-hydroxyalkyl-3,5-dimethylpyrazole ligands. Cleavage of the N(pz)C(sp3) bond. X-ray crystal structure of cis-[PtCl2(HL2)2] (HL2=1-(2-hydroxyethyl)-3,5-dimethylpyrazole) and trans-[PtCl2(dmpz)2] (dmpz=3,5-dimethylpyrazole)

The reactions of 1-hydroxymethyl-3,5-dimethylpyrazole (HL 1 ) and 1-(2-hydroxyethyl)-3,5-dimethylpyrazole (HL 2 ) with several platinum starting materials ([PtCl 2 (CH 3 CN) 2 ], cis - and trans -[PtCl 2 (PhCN) 2 ], PtCl 2 and K 2 PtCl 4 ) under different conditions have been examined and compared with those obtained from the reactions with Pd(II). cis and trans Pt(II) adducts are obtained in a different ratio depending on the metallic starting complex. The reaction of HL 1 with any of the Pt(II) complexes differs from that with Pd(II) and also from the equivalent reaction of HL 2 with Pt(II). This reaction implies the rupture of the ligand: the cleavage of the N(pz)C(sp 3 ) bond leads to [PtCl 2 (dmpz) 2 ] (dmpz=3,5-dimethylpyrazole). For comparison, the direct reaction of dmpz with Pt(II) has also been studied. The crystal structure of cis -[PtCl 2 (HL 2 ) 2 ] and trans -[PtCl 2 (dmpz) 2 ] are here reported.

Ion-directed assembly of gold nanorods: a strategy for mercury detection.

Water-soluble gold nanorods (Au NRs) have been functionalized with an N-alkylaminopyrazole ligand, 1-[2-(octylamino)ethyl]-3,5-diphenylpyrazole (PyL), that has been demonstrated able to coordinate heavy metal ions. The N-alkylaminopyrazole functionalized Au NRs have been characterized by electron microscopy and spectroscopic investigation and tested in optical detection experiments of different ions, namely, Zn(2+), Cd(2+), Hg(2+), Cu(2+), Pb(2+), and As(3+). In particular, the exposure of the functionalized NRs to increasing amounts of Hg(2+) ions has resulted in a gradual red-shift and broadening of the longitudinal plasmon band, up to 900 nm. Interestingly, a significantly different response has been recorded for the other tested ions. In fact, no significant shift in the longitudinal plasmon band has been observed for any of them, while a nearly linear reduction in the plasmon band intensity versus ion concentration in solution has been detected. The very high sensitivity for Hg(2+) with respect to other investigated ions, with a limit of detection of 3 ppt, demonstrates that the functionalization of Au NRs with PyL is a very effective method to be implemented in a reliable colorimetric sensing device, able to push further down the detection limit achieved by applying similar strategies to spherical Au NPs.