Modular synthesis of semiconducting graft co-polymers to achieve ‘clickable’ fluorescent nanoparticles with long circulation and specific cancer targeting

Semiconducting polymer nanoparticles (SPNs) are explored for applications in cancer theranostics because of their high absorption coefficients, photostability, and biocompatibility. However, SPNs are susceptible to aggregation and protein fouling in physiological conditions, which can be detrimental for in vivo applications. Here, a method for achieving colloidally stable and low-fouling SPNs is described by grafting poly(ethylene glycol) (PEG) onto the backbone of the fluorescent semiconducting polymer, poly(9,9′-dioctylfluorene-5-fluoro-2,1,3-benzothiadiazole), in a simple one-step substitution reaction, postpolymerization. Further, by utilizing azide-functionalized PEG, anti-human epidermal growth factor receptor 2 (HER2) antibodies, antibody fragments, or affibodies are site-specifically “clicked” onto the SPN surface, which allows the functionalized SPNs to specifically target HER2-positive cancer cells. In vivo, the PEGylated SPNs are found to have excellent circulation efficiencies in zebrafish embryos for up to seven days postinjection. SPNs functionalized with affibodies are then shown to be able to target HER2 expressing cancer cells in a zebrafish xenograft model. The covalent PEGylated SPN system described herein shows great potential for cancer theranostics

The degree of positive ionization of sputtered metal clusters

The results of recent experimental studies of the degree of positive ionization of clusters sputtered from a number of metal surfaces by keV-ion bombardment are analyzed in terms of an earlier proposed model. The model assumes that in addition to electron exchange, there exists another mechanism of cluster ionization - thermionic emission of electrons from clusters. The calculations qualitatively reproduce the experimental data. (C) 2001 Elsevier Science B.V. All rights reserved

Effect of the electronic subsystem excitation on the ionisation probability of atoms sputtered from metals by atomic and molecular projectiles

In the present work an effect of excitation of the metal electronic subsystem on the ionisation probability of atoms sputtered under fast ion bombardment has been studied. Atomic and molecular primary ions with the same velocity were used to produce different degrees of the electronic excitations. Information on the ionisation probability was obtained from the kinetic energy distributions of Nb+ and Ta+ ions sputtered from the respective clean Nb and Ta targets by Au-m(-) projectiles (1 less than or equal tom less than or equal to3) with the energy of E-0 = 6 keV per atom. It was found that, as compared with the atomic ion bombardment (m = 1), the molecular one (m = 2,3) leads to the increase of the ionisation probability P-m(+) (P-1(+) < P-2(+) < P-3(+)). Such an effect depends on the kinetic energy E of the secondary ions, increasing with decreasing E. It was shown that the bombardment of metals by the molecular projectiles produces non-additive sputtering of atomic ions, which is determined by the joint action of such two factors as non-additive sputtering of atoms and non-additive process of their charge state formation. The results obtained are discussed in the framework of the model where the charge state formation occurs in electron exchange between sputtered atoms and a local surface area excited by the impact of the projectile. (C) 2001 Elsevier Science B.V. All rights reserved

X-Ray and spectroscopic re-investigation of urotropine-p-nitrophenol complex

The product of the reaction between urotropine and p-nitrophenol, reported as a 1:1 adduct that belongs to the triclinic P 1 space group, is, in fact, a 1:2 [C6H12N4]. (p-HOC6H4NO2](2). [H2O] hydrate that crystallizes in the monoclinic C2 space group. In the crystal structure, one nitrogen atom of the urotropine moiety is linked by a hydrogen bond to the hydroxyl group of a p-nitrophenol molecule [N . . .O = 2.655 (7) Angstrom]; the [C6H12N4]. [p-HOC6H4NO2] entities are linked into a linear one-dimensional chain through the lattice water molecule [O . . .N = 2.871 (8), O . . .O = 2.878 (7) Angstrom]. The other p-nitrophenol moiety is disordered over two positions across the two-fold axis; its interaction with adjacent water molecules [O . . .O = 2.53 (1), 2.57 (2) Angstrom] holds neighboring chains together. The FTIR spectrum of the complex in the solid indicate the formation of OH . . .N intermolecular hydrogen bond described by an asymmetric double minimum potential and weak Zundel's polarizability. The spectroscopic measurements in solution demonstrate the dissociation of the complex observed in the solid and prove the presence of the 1:1 complexes urotropine-p-nitrophenol. In these complexes no proton transfer from p-nitrophenol to urotropine is observed. (C) 2001 Elsevier Science B.V. All rights reserved

Evaluation of the elastic properties of bulk metallic glasses

The development of bulk metallic glasses as a prominent class of functional and structural materials has attracted considerable interest in the last years. One of the fundamental physical quantities necessary to describe the mechanical properties of the materials is the bulk modulus. In the present article, a simple method to estimate the bulk modulus and its pressure derivative is proposed. It is shown that these quantities can be estimated from the values of the constituent elements and their compositions. Comparison with measured data shows good agreement. The physical background of the method is discussed based on the jellium model of metals