Popcorn‐Shaped Magnetic Core–Plasmonic Shell Multifunctional Nanoparticles for the Targeted Magnetic Separation and Enrichment,Label‐Free SERS Imaging,and Photothermal Destruction of Multidrug‐Resistant Bacteria

Over the last few years, one of the most important and complex problems facing our society is treating infectious diseases caused by multidrug‐resistant bacteria (MDRB), by using current market‐existing antibiotics. Driven by this need, we report for the first time the development of the multifunctional popcorn‐shaped iron magnetic core–gold plasmonic shell nanotechnology‐driven approach for targeted magnetic separation and enrichment, label‐free surface‐enhanced Raman spectroscopy (SERS) detection, and the selective photothermal destruction of MDR Salmonella DT104. Due to the presence of the “lightning‐rod effect”, the core–shell popcorn‐shaped gold‐nanoparticle tips provided a huge field of SERS enhancement. The experimental data show that the M3038 antibody‐conjugated nanoparticles can be used for targeted separation and SERS imaging of MDR Salmonella DT104. A targeted photothermal‐lysis experiment, by using 670 nm light at 1.5 W cm^?2 for 10 min, results in selective and irreparable cellular‐damage to MDR Salmonella. We discuss the possible mechanism and operating principle for the targeted separation, label‐free SERS imaging, and photothermal destruction of MDRB by using the popcorn‐shaped magnetic/plasmonic nanotechnology.     

Phenotyping Metastatic Brain Tumors Applying Spectrochemical Analyses: Segregation of Different Cancer Types

Metastatic brain tumors represent a significant proportion of tumors identified intraoperatively. A rapid diagnostic method, circumventing the need for histopathology studies, could prove clinically useful. As many spectroscopic studies have shown ability to differentitate between different tumor types, this technique was evaluated for use within metastatic brain tumors. Spectrochemical approaches [Raman and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) spectroscopy] were applied to determine how readily they may identify the primary site for the metastatic tumor. Metastases were from primary adenocarcinomas of lung (n?=?7) and colorectum (n?=?7), and for comparison, metastatic melanoma (n?=?7). The objective was to determine if Raman or ATR-FTIR spectroscopy could delineate the origin of the primary tumor. The results demonstrate that there are marked similarities between the two adenocarcinoma groups and whilst Raman and ATR-FTIR can distinguish the three groups with limited success, classification accuracy is greatly improved when combining the adenocarcinoma groups. The use of such techniques in the clinical setting is more likely to be found intraoperatively, determining the presence of a tumor and suggesting the tumor class; however, traditional histopathology would still be needed to identify the primary origin of the tumor.     

Plasma Copolymerization of Acrylic Acid with Hexamethyldisilazane

Polymerization of acrylic acid with hexamethyldisilazane (HMSZ) was carried out in a mixture by use of pulsed and continuous wave plasmas. The polymer deposition rate and the chemical structures of product films were investigated with regard to the power effects of the plasmas. A copolymer-like structure was formed in general, but the products were not necessarily composed of the simple agglomeration of the polymer components. The power consumed in plasma polymerization influenced the chemical structure, and oxide, in the form of Si—O, was produced more densely in the polymers at higher rather than lower powers. The polymer structure was related to the chemical properties, and the surface wetting was also changed by the power used in the plasma copolymerization. The films were moderately hydrophilic in the polymers produced at lower wattages, but became as hydrophobic as those from HMSZ when prepared at high wattages.     

Structural, spectroscopic and redox properties of uranyl complexes with a maleonitrile containing ligand

The reaction of uranyl nitrate hexahydrate with the maleonitrile containing Schiff base 2,3-bis[(4-diethylamino-2-hydroxybenzylidene)amino]but-2-enedinitrile (salmnt((Et(2)N)(2))H(2)) in methanol produces [UO(2)(salmnt((Et2N)2))(H(2)O)] (1) where the uranyl equatorial coordination plane is completed by the N(2)O(2) tetradentate cavity of the (salmnt((Et(2)N)(2)))(2-) ligand and a water molecule. The coordinated water molecule readily undergoes exchange with pyridine (py), dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF) and triphenylphosphine oxide (TPPO) to give a series of [UO(2)(salmnt((Et(2)N)(2)))(L)] complexes (L = py, DMSO, DMF, TPPO; 2-5, respectively). X-Ray crystallography of 1-5 show that the (salmnt((Et(2)N)(2)))(2-) ligand is distorted when coordinated to the uranyl moiety, in contrast to the planar structure observed for the free protonated ligand (salmnt((Et(2)N)(2))H(2)). The Raman spectra of 1-5 only display extremely weak bands (819-828 cm(-1)) that can be assigned to the typically symmetric O=U=O stretch. This stretching mode is also observed in the infrared spectra for all complexes 1-5 (818-826 cm(-1)) predominantly caused by the distortion of the tetradentate (salmnt((Et(2)N)(2)))(2-) ligand about the uranyl equatorial plane resulting in a change in dipole for this bond stretch. The solution behaviour of 2-5 was studied using NMR, electronic absorption and emission spectroscopy, and cyclic voltammetry. Complexes 2-5 exhibit intense absorptions in the visible region of the spectrum due to intramolecular charge transfer (ICT) transitions and the luminescence lifetimes (< 5 ns) indicate the emission arises from ligand-centred excited states. Reversible redox processes assigned to the {UO(2)}(2+)/{UO(2)}(+) couple are observed for complexes 2-5 (2: E(1/2) = -1.80 V; 3,5: E(1/2) = -1.78 V; 4: E(1/2) = -1.81 V : vs. ferrocenium/ferrocene {Fc(+)/Fc}, 0.1 M Bu(4)NPF(6)) in dichloromethane (DCM). These are some of the most negative half potentials for the {UO(2)}(2+)/{UO(2)}(+) couple observed to date and indicate the strong electron donating nature of the (salmnt((Et(2)N)(2)))(2-) ligand. Multiple uranyl redox processes are clearly seen for [UO(2)(salmnt((Et(2)N)(2)))(L)] in L (L = py, DMSO, DMF; 2-4: 0.1 M Bu(4)NPF(6)) indicating the relative instability of these complexes when competing ligands are present, but the reversible {UO(2)}(2+)/{UO(2)}(+) couple for the intact complexes can still be assigned and shows the position of this couple can be modulated by the solvation environment. Several redox processes were also observed between +0.2 and +1.2 V (vs. Fc(+)/Fc) that prove the redox active nature of the maleonitrile-containing ligand.     

Progress toward an expanded eukaryotic genetic code

Expanding the eukaryotic genetic code to include unnatural amino acids with novel properties would provide powerful tools for manipulating protein function in eukaryotic cells. Toward this goal, a general approach with potential for isolating aminoacyl-tRNA synthetases that incorporate unnatural amino acids with high fidelity into proteins in Saccharomyces cerevisiae is described. The method is based on activation of GAL4-responsive HIS3, URA3, or lacZ reporter genes by suppression of amber codons in GAL4. The optimization of GAL4 reporters is described, and the positive and negative selection of active Escherichia coli tyrosyl-tRNA synthetase (EcTyrRS)/tRNA(CUA) is demonstrated. Importantly, both selections can be performed on a single cell and with a range of stringencies. This method will facilitate the isolation of a range of aminoacyl-tRNA synthetase (aaRS)/tRNA(CUA) activities from large libraries of mutant synthetases.     

GENETIC AND PHYSIOLOGICAL STUDIES OF THE EFFECT OF LIGHT ON THE DEVELOPMENT OF THE MOSS, PHYSCOMITRELLA PATENS

The germination of Physcomitrella patens spores only occurs when wet spores are exposed to light. Depending on their ripeness, spores require from 44 to 64 h illumination to bring about maximum germination. There is a lag period of about 15 h between the reception of sufficient light to elicit germination before germination can be observed. Wavelengths in the range 640–64080 nm are much more effective in inducing germination than longer or shorter wavelengths, but far-red reversal of red light induction of germination has not been demonstrated. Light also has very marked effects on protonemal and gametophore development. In darkness, only caulonemata are produced, and these grow negatively geotropically. No new gametophores develop but existing gametophores grow negatively geotropically, etiolate and bear only scale leaves. In light, chloronemata, as well as caulonemata are produced, the former grow positively phototropically, while the latter grow at right angles to the direction of light, and neither cell type is sensitive to gravity. In the light, gametophores grow positively phototropically, are indifferent to gravity, produce large leaves and do not etiolate. All these responses to light by protonemata and gametophores are shown by cultures growing in a 23 h dark/l h red light cycle, but if this red light treatment is followed by 15min far-red light, the effect of the red light is reversed, indicating an involvement of phytochrome in the mediation of these responses. Mutants showing abnormal growth in the dark have been isolated, as well as mutants having abnormal phototropic responses. The latter type has lost the phototropic response of both the protonemal cell types, as well as of gametophores, indicating that these different responses may share a common component.     

Synthesis and properties of polyaromatic dendrimers possessing a repetitive amide-ester coupling sequence

A series of novel polyaromatic dendrimers that feature tris-(2-ethylamino)amine as the central core unit has been synthesized up to the third generation by employing a convergent growth strategy. The building blocks 1,3-diamino-2-hydroxypropane and 4-carboxybenzaldehyde were used for dendron construction, a process that involved the cyclic repetition of esterification, oxidation and selective amidation steps. Molecular modelling of this class of dendrimers has been used to predict potential solution state conformations employing molecular mechanics and molecular dynamic simulations. In addition, the results of preliminary metal binding studies using the first generation dendritic system are also outlined.     

Introduction of bis-discotic and bis-calamitic mesogenic addends to C 60

The synthesis and characterization of four C 60 Bingel cyclopropanation adducts incorporating bis-biphenylene (three adducts) and bis-triphenylene (one adduct) moieties are described. The thermal analysis (POM and DSC) of these materials reveals that they are not liquid crystalline. However, two of the precursor bis-biphenylene malonate esters possess monotropic mesophases. Furthermore, each of the corresponding C₆₀adducts is miscible in the melts of the precursor malonate ester, and at low dopings, retains the liquid crystalline monotropic mesophases of the precursor.