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An ultra-wideband Vivaldi antipodal antenna with high gain is presented. A CSRR array and T-shaped strips were developed to embedded in the tapered slot antenna, which improves VSWR and gain performances, especially in the low frequency regions. Simulation results have been presented with a fractional impedance bandwidth of 186% from 1 GHz to 28 GHz for VSWR

Mass cytometry is a highly multiplexed single-cell analysis platform that uses metal-tagged reagents to identify multiple cellular biomarkers. The current metal-tagged reagent preparation employs thiol–maleimide chemistry to covalently couple maleimide-functionalized metal-chelating polymers (MCPs) with antibodies (Abs), a process that requires partial reduction of the Ab to form reactive thiol groups. However, some classes of Abs (for example, IgM) as well as biomolecules lacking cysteine residues have been challenging to label using this method. This inherent limitation led us to develop a new conjugation strategy for labeling a wide range of biomolecules and affinity reagents. In this report, we present a metal tagging approach using a new class of azide- or transcyclooctene-terminated MCPs with copper(I)-free strain-promoted alkyne–azide cycloaddition or tetrazine–alkene click chemistry reactions, in which biomolecules with -NH2 functional groups are selectively activated with a dibenzocyclooctyne or ...

A novel instrument for real time analysis of individual biological cells or other microparticles is described. The instrument is based on inductively coupled plasma time-of-flight mass spectrometry and comprises a three-aperture plasma-vacuum interface, a dc quadrupole turning optics for decoupling ions from neutral components, an rf quadrupole ion guide discriminating against low-mass dominant plasma ions, a point-to-parallel focusing dc quadrupole doublet, an orthogonal acceleration reflectron analyzer, a discrete dynode fast ion detector, and an 8-bit 1 GHz digitizer. A high spectrum generation frequency of 76.8 kHz provides capability for collecting multiple spectra from each particle-induced transient ion cloud, typically of 200-300 micros duration. It is shown that the transients can be resolved and characterized individually at a peak frequency of 1100 particles per second. Design considerations and optimization data are presented. The figures of merit of the instrument are measured under standard inductively coupled plasma (ICP) operating conditions (3% cerium oxide ratio). At mass resolution (full width at half-maximum) M/DeltaM900 for m/z = 159, the sensitivity with a standard sample introduction system of1.4 x 10(8) ion counts per second per mg L(-1) of Tb and an abundance sensitivity of (6 x 10(-4))-(1.4 x 10(-3)) (trailing and leading masses, respectively) are shown. The mass range (m/z = 125-215) and abundance sensitivity are sufficient for elemental immunoassay with up to 60 distinct available elemental tags. When15 elemental tags are used, a higher sensitivity mode at lower resolution (M/DeltaM500) can be used, which provides2.4 x 10(8) cps per mg L(-1) of Tb, at (1.5 x 10(-3))-(5.0 x 10(-3)) abundance sensitivity. The real-time simultaneous detection of multiple isotopes from individual 1.8 microm polystyrene beads labeled with lanthanides is shown. A real time single cell 20 antigen expression assay of model cell lines and leukemia patient samples immuno-labeled with lanthanide-tagged antibodies is presented.

To identify a rare (e.g., diseased or foreign) cell in a complex mixture, or to understand the proteomic complexity[1,2] of cells, one needs to be able to measure simultaneously and quantitatively a large number of proteins or other biomarkers that may be present in a complex sample. This is a difficult task and is beyond the reach of current capabilities. To address a problem of this complexity, we have begun to develop a high-sensitivity assay[3–6] based upon elemental tags that will enable the simultaneous measurement of many proteins in a single sample. The advantage of this approach lies in the large number of available elements and isotopes (potentially greater than 79) found in low abundance in biological systems, which will allow multiple tags to be used simultaneously. Inductively coupled plasma mass spectrometry (ICP-MS) is an ideal technique for detecting and quantifying these tags, as ICP-MS provides excellent resolution between the tag masses and an exceptional dynamic range (nine orders of magnitude).[7] This method allows one to overcome some of the limitations of currently available fluorescent tagging approaches.[8] These limitations arise from the spectral overlap of different dyes and the difficulty in measuring simultaneously targets that differ in abundance by an order of magnitude or more. Other benefits of ICP-MS detection include the high sensitivity, which is comparable to that of radioimmunoassays or chemiluminescent assays,[3] insensitivity of elemental tags to photobleaching and storage time, as well as the stability of the tagged sample so that it can be stored or shipped for analysis. We discuss herein the development of a new class of elemental tags for ICP-MS detection and their use for tagging of antibodies chosen to allow specific recognition of distinguishing cell surface markers. By using this technique it should be possible to achieve detection limits on the order of parts per billion, which will allow the detection of cell surface markers with copy numbers as low as 100.

Multiwalled carbon nanotubes (MWNTs) with two different diameters were dispersed within poly( is an element of-caprolactone) (PCL) by melt-blending and coprecipitation, respectively, with the purpose to impart good electromagnetic interference shielding properties to the polyester. Transmission electron microscopy showed that the MWNTs were uniformly dispersed as single nanotubes within the matrix. Because the nanotubes were broken down during melt-blending, the percolation threshold was observed at a lower filler content in the case of coprecipitation. Substitution of poly(ethylene-co-octene), poly( vinyl chloride), polypropylene, and polystyrene for PCL resulted in a much lower shielding efficiency. Finally, polycarbonate and poly( methyl methacrylate) appeared as promising substitutes for PCL, suggesting that pi-pi interactions between the nanotubes and constitutive carbonyl units of the polymers would be beneficial to the dispersion and ultimately to the electrical properties of the nanocomposites.

We report passivation of CdSe and CdSe/ZnS nanocrystals (NCs) with poly(N,N-dimethylaminoethyl methacrylate) (PDMA) through a ligand exchange process. We present the results from various techniques that were used to verify that ligand exchange occurred, including 1H NMR, 31P NMR, and changes in solubility/colloidal properties, hydrodynamic radius, and photoluminescence. We have examined the effect of polymer molecular weight on the surface passivation and quantum yields of the NCs. As additional evidence for the binding of the polymer to the surface of the NC, we were able to modify the polymer chemically to render the NC−polymer moiety water-soluble.

Pyrene-containing polymers have been prepared for noncovalent sidewall functionalization of multiwalled carbon nanotubes (MWNTs). (1-Pyrene)methyl 2-methyl-2-propenoate (PyM-MP) has been synthesized and copolymerized with methyl methacrylate (MMA). Poly(ethylene-co-butylene)-b-poly(MMA-co-PyMMP) diblocks have also been synthesized. The surface of MWNTs, produced by both the CCVD and arc discharge methods, has been modified by these copolymers for making them dispersible in a variety of organic solvents. The modified MWNTs have been characterized by thermogravimetric analysis, transmission electron microscopy, and atomic force microscopy.

Multi-walled carbon nanotubes (MWNTs) have been successfully modified by polystyrene, poly(ɛ-caprolactone), and their block copolymers by addition reaction of the alkoxyamine-terminated precursors. Polymer-modified MWNTs are easily dispersed in good solvents for the grafted polymer, such as toluene and THF. This observation has been confirmed by TEM analysis. The grafting ratio of polystyrene chains at the surface of MWNTs depends on the polymer molecular weight.

A highly versatile strategy was implemented in order to attach a range of polymer grafts and functional groups along the backbone of poly(e-caprolactone). α-Chloro-e-caprolactone (αCleCL) was first prepared by the Baeyer−Villiger oxidation of α-chlorocyclohexanone. This monomer (αCleCL) was then copolymerized with e-caprolactone in the presence of 2,2-dibutyl-2-stanna-1,3-dioxepane. Finally, the pendant activated chlorides of the copolymer were used to initiate (i) the “grafting from” of poly(methyl methacrylate) by atom transfer radical polymerization and (ii) the grafting of benzoate groups by atom transfer radical addition of 3-butenyl benzoate.

Multi-walled carbon nanotubes (MWNTs) have been successfully modified with polyacrylonitrile (PAN) by a cathodic electrochemical process. The surface-modified MWNTs afforded are then dispersible in good solvents for PAN, such as N,N-dimethylformamide (DMF). Collected from a dilute dispersion, these MWNTs are essentially disentangled, as confirmed by transmission electron microscopy (TEM) analysis. From the differential scanning calorimetry (DSC) traces for polyacrylonitrile and polyacrylonitrile-grafted MWNTs, the maximum grafting ratio is estimated at 0.28.

A pure unsaturated cyclic ester, 6,7-dihydro-2(3H)-oxepinone (DHO2), was prepared by a new synthetic route. The copolymerization of DHO2 with ϵ-caprolactone (ϵCL) was initiated by aluminum isopropoxide [Al(OiPr)3] at 0 °C as an easy way to produce unsaturated aliphatic polyesters with nonconjugated CC double bonds in a controlled manner. The chain growth was living, as certified by the agreement between the experimental molecular weight at total monomer conversion and the value predicted from the initial monomer/initiator molar ratio. The polydispersity was reasonably low (weight-average molecular weight/number-average molecular weight ≤ 1.2). The homopolymerization of DHO2 was, however, not controlled because of fast intramolecular transesterification. Copolymers of DHO2 and ϵCL were quantitatively oxidized with the formation of epoxides containing chains. The extent of the epoxidation allowed the thermal properties and thermal stability of the copolyesters to be modulated. The epoxidized copolyesters were successfully converted into thioaminated chains, which were then quaternized into polycations. No degradation occurred during the chemical modification. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2286–2297, 2002

Poly(δ-valerolactone) [poly(δVL)] of high molecular weight (∼40 000) and low polydispersity index (∼1.05) was prepared by activated monomer cationic ring-opening polymerization of δ-VL initiated by the alcohol/HCl·Et2O system. A series of functional alcohols, e.g., 9-anthracenemethanol, 2-hydroxyethyl acrylate, 3-buten-1-ol, 2-bromoethanol, and 5-norbornene-2-methanol, were successfully used to prepare asymmetric telechelic poly(δVL), i.e., chains end-capped by the functional group of the alcohol in α-position and by an ω-hydroxyl group. Ring-opening polymerization of δ-VL in the presence of α-methoxy-ω-hydroxylpoly(ethylene oxide) and poly(ethylene glycol) led to amphiphilic di- and triblock copolymers, respectively. The polydispersity index of all these (co)polymers was low (∼1.10).

γ-Acryloyloxyethyl-γ-butyrolactone is formed as a byproduct when the polymerization of γ-acryloyloxy-e-caprolactone is initiated with aluminium isopropoxide in toluene. The extent of this side reaction decreases with decreasing temperature and is dependent on whether the reaction is stopped as soon as monomer conversion is complete or not. A two-step backbiting mechanism is proposed for this intramolecular transesterification reaction.

Homopolymerization of the unsaturated cyclic ester, 6,7-dihydro-2(5H)-oxepinone (DHO), and copolymerization with e-caprolactone (eCL) are an easy way to produce unsaturated aliphatic polyesters in a controlled manner. Polymerization of DHO initiated by Al(OiPr)3 in toluene at room temperature proceeds by a coordination−insertion mechanism and is living as certified by the agreement between the experimental molecular weight at total monomer conversion and the value predicted from the initial monomer to initiator molar ratio. The polydispersity is also low (Mw/Mn ≤ 1.2). Random copolymerization of DHO and eCL leads to the same conclusion. Beyond the complete monomer conversion, the poly(DHO) chains experience mainly intermolecular transesterification reactions at the same rate as poly(eCL) under the same conditions. The livingness of the ROP of both DHO and eCL allows diblock copolymers to be synthesized with predicted composition and molecular weight. Homopoly(DHO) is semicrystalline with Tm at 35 °C and T...

New functional aliphatic polyesters were prepared by chemical modification of brominated copolyesters. Poly(e-caprolactone)-co-poly(γ-(2-bromo-2-methylpropionate)-e-caprolactone) copolymer was prep...

The aluminum alkoxide mediated ring opening polymerization of functional lactones, such as γ-ethylene ketal-ϵ-caprolactone (TOSUO), γ-(triethylsilyloxy)-ϵ-caprolactone (SCL) and γ-bromo-ϵ-caprolactone (γBrCL), is a versatile route to polyesters containing ketal, ketone, alcohol and bromide groups. As result of living polyaddition mechanism, random and block copolymerization of ϵCL and γBrCL has been successfully carried out. The reactivity ratios are quite similar (1.08 for ϵ-CL, and 1.12 for γBrCL). These random copolymers are semicrystalline when they contain less than 30 mol% of γBrCL, otherwise they are amorphous. No transesterification reaction occurs during the sequential polymerization of ϵ-CL and γBrCL leading to block copolymers. Reaction of poly(ϵCL-co-γBrCL) with pyridine provides quantitatively a polycationic polyester. Furthermore, the reaction of this random copolymer with 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU) is a route to unsaturated polyesters, whose the non conjugated double bonds can be quantitatively converted into epoxides by reaction with m-chloroperbenzoic acid (mCPBA). No chain degradation is detected during these derivatization reactions of poly(ϵCL-co-γBrCL).

The living free radical ring-opening polymerization of 2-methylene-4-phenyl-1,3-dioxolane (MPDO) in the presence of ethyl α-bromobutyrate/CuBr/2,2'-bipyridine at various temperatures has been investigated. In comparison with the conventional ring-opening polymerization of MPDO, a lower content of ring-opened unit in the polymer was found. The results of ln[M] 0 /[M]) against polymerization time, (M n ) th and (M n ) NMR vs conversion, and GPC of the polymers are strongly indicative of the living polymerization process. Initiator efficiency was measured. The mechanism of polymerization, and the effect of pyridine on the polymerization mechanism were discussed.

We describe the synthesis and characterization of metal-chelating polymers with a degree of polymerization of 67 and 79, high diethylenetriaminepentaacetic acid (DTPA) functionality, M(w)/M(n) ≤ 1.17, and a maleimide as an orthogonal functional group for conjugation to antibodies. The polymeric disulfide form of the DP(n) = 79 DTPA polymer was analyzed by thermogravimetric analysis to determine moisture and sodium-ion content and by isothermal titration calorimetry (ITC) to determine the Gd(3+) binding capacity. These results showed each chain binds 68 ± 7 Gd(3+) per chain. Secondary goat antimouse IgG was covalently labeled with the maleimide form of the DTPA polymer (DP(n) = 79) carrying (159)Tb. Conventional ICPMS analysis of this conjugate showed each antibody carried an average of 161 ± 4 (159)Tb atoms. This result was combined with the ITC result to show there are an average of 2.4 ± 0.3 polymer chains attached to each antibody. Eleven monoclonal primary antibodies were labeled with different lanthanide isotopes using the same labeling methodology. Single cell analysis of whole umbilical cord blood stained with a mixture of 11 metal-tagged antibodies was performed by mass cytometry.

Advances in the development of highly multiplexed bio-analytical assays with inductively coupled plasma mass spectrometry (ICP-MS) detection are discussed. Use of novel reagents specifically designed for immunological methods utilizing elemental analysis is presented. The major steps of method development, including selection of elements for tags, validation of tagged reagents, and examples of multiplexed assays, are considered in detail. The paper further describes experimental protocols for elemental tagging of antibodies, immunostaining of live and fixed human leukemia cells, and preparation of samples for ICP-MS analysis. Quantitative analysis of surface antigens on model cell lines using a cocktail of seven lanthanide labeled antibodies demonstrated high specificity and concordance with conventional immunophenotyping.

The enumeration of absolute cell numbers and cell proliferation in clinical samples is important for diagnostic and research purposes. Detection of cellular DNA with fluorescent dyes is the most commonly used approach for cell enumeration in cytometry. Inductively coupled plasma mass spectrometry (ICPMS) has been recently introduced to the field of protein and cell surface antigen identification via ICPMS-linked immunoassays using element-labeled affinity reagents such as gold and lanthanide-conjugated antibodies. In the present work, we describe novel methods for using metallointercalators that irreversibly bind DNA and low concentrations of rare earth metals added to cell growth media for rapid and sensitive measurement of cell numbers by mass spectrometry. We show that Ir- and Rh-containing metallointercalators are useful reagents for labeling cells and normalizing signals when studying antigen expression on different types and numbers of cells. Results are presented for solution analysis performed by conventional ICPMS and compared to measurements obtained on the novel flow cytometer mass spectrometer (FC-MS) instrument, designed to analyze multiple antigens and DNA simultaneously in single cells.

Nanoparticles can be used for decoration and functionalization of single polymer molecules that have been adsorbed to a solid substrate. Initial attempts to prepare Prussian Blue nanoclusters by a layer-by-layer deposition technique of hexacyanoferrate anions and ferric cations onto isolated polycation chains in water failed because of the desorption of the first layer upon deposition of the next one. A simple method for the preparation of charge-stabilized Prussian Blue nanoparticles of readily adjustable size is reported. Prussian Blue nanoparticles have been purified by addition of non-solvents and redispersed in water without aggregation. Thus formed Prussian Blue nanoparticles are crystalline and display a long-range ferromagnetic ordering at 5.1 K. Prussian Blue nanoparticles were selectively deposited along single polycation molecules to form a one-dimensional array or were attached to the surface of carbon nanotubes (CNTs) functionalized with poly2-vinylpyridine (P2VP). These nanoparticle-based nano-structures might be useful materials for manufacture of electrooptical devices, or mechanically robust ion-sieving membranes.

In this paper, we present a new shielding and absorbing composite based on carbon nanotubes (CNTs) dispersed inside a polymer dielectric material. The extremely high aspect ratio of CNTs and their remarkable conductive properties lead to good absorbing properties with very low concentrations. A broadband characterization technique is used to measure the microwave electrical properties of CNT composites. It is shown that a conduction level of 1 S/m is reached for only 0.35 wt % of a CNT, while, for a classical absorbing composite based on carbon black, 20% concentration is mandatory. The conductive properties are explained by a phenomenological electrical model and successfully correlated with rheological data aiming at monitoring the dispersion of conductive inclusions in polymer matrices

Ring-opening polymerization (ROP) and ring-opening metathesis polymerization (ROMP) of an unsaturated ε-caprolactone, 6,7-dihydro-2(3H)-oxepinone (DHO2), are alternative routes to produce unsaturated aliphatic polyesters with the same molecular structure. Polymerization of DHO2 initiated by Al isopropoxide in toluene at room temperature or at 0°C proceeds by a coordination-insertion mechanism, although intramolecular transesterification takes place beyond complete monomer conversion. The molecular weight distribution is narrow as long as monomer conversion does not exceed 90%. Ring-opening metathesis polymerization of DHO2 initiated by Schrock’s Mo-based catalyst, 1, at 60°C allows higher molecular weight unsaturated polyester to be prepared, even though an intramolecular side reaction also operates. The structure of poly(DHO2) synthesized by ROP and ROMP is the same, as confirmed by 1H, 13C NMR, and FT-IR spectra. Copolymers of DHO2 with norbornene, cis-cyclooctene, and 1,5-cyclooctadiene have been successfully prepared.

This paper reports on the decisive effect that solvent has on the atom transfer radical polymerization of methyl methacrylate (MMA) at low temperature. In butanone and in the presence of a copper(I)/bipyridine complex, the polymerization is controlled and the molecular weight distribution is narrow, at 0 °C and even lower. This control is maintained when e-caprolactone (CL) is substituted for butanone. The use of this polymerizable solvent together with a novel dual initiator, 2-hydroxyethyl, 2'- methyl-2'-bromopropionate, is an efficient strategy to prepare PMMA-b-PCL diblock polymers in a one-pot process.