Nanotechnology-Assisted Cell Tracking

The usefulness of nanoparticles (NPs) in the diagnostic and/or therapeutic sector is derived from their aptitude for navigating intra-and extracellular barriers successfully and to be spatiotemporally targeted. In this context, the optimization of NP delivery platforms is technologically related to the exploitation of the mechanisms involved in the NP–cell interaction. This review provides a detailed overview of the available technologies focusing on cell–NP interaction/detection by describing their applications in the fields of cancer and regenerative medicine. Specifically, a literature survey has been performed to analyze the key nanocarrier-impacting elements, such as NP typology and functionalization, the ability to tune cell interaction mechanisms under in vitro and in vivo conditions by framing, and at the same time, the imaging devices supporting NP delivery assessment, and consideration of their specificity and sensitivity. Although the large amount of literature information on the designs and applications of cell membrane-coated NPs has reached the extent at which it could be considered a mature branch of nanomedicine ready to be translated to the clinic, the technology applied to the biomimetic functionalization strategy of the design of NPs for directing cell labelling and intracellular retention appears less advanced. These approaches, if properly scaled up, will present diverse biomedical applications and make a positive impact on human health

Spatial Guilds in the Serengeti Food Web Revealed by a Bayesian Group Model

Food webs, networks of feeding relationships among organisms, provide fundamental insights into mechanisms that determine ecosystem stability and persistence. Despite long-standing interest in the compartmental structure of food webs, past network analyses of food webs have been constrained by a standard definition of compartments, or modules, that requires many links within compartments and few links between them. Empirical analyses have been further limited by low-resolution data for primary producers. In this paper, we present a Bayesian computational method for identifying group structure in food webs using a flexible definition of a group that can describe both functional roles and standard compartments. The Serengeti ecosystem provides an opportunity to examine structure in a newly compiled food web that includes species-level resolution among plants, allowing us to address whether groups in the food web correspond to tightly-connected compartments or functional groups, and whether network structure reflects spatial or trophic organization, or a combination of the two. We have compiled the major mammalian and plant components of the Serengeti food web from published literature, and we infer its group structure using our method. We find that network structure corresponds to spatially distinct plant groups coupled at higher trophic levels by groups of herbivores, which are in turn coupled by carnivore groups. Thus the group structure of the Serengeti web represents a mixture of trophic guild structure and spatial patterns, in contrast to the standard compartments typically identified in ecological networks. From data consisting only of nodes and links, the group structure that emerges supports recent ideas on spatial coupling and energy channels in ecosystems that have been proposed as important for persistence.Comment: 28 pages, 6 figures (+ 3 supporting), 2 tables (+ 4 supporting

Species-specific, pan-European diameter increment models based on data of 2.3 million trees

ResearchBackground: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obtained from National Forest Inventories or from long-term research plots. Many of these models include country- and location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to apply models outside the region or country they were developed for. However, there is a clear need for more generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires the development of models that are applicable across the European continent. The purpose of this study is to develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil and nutrient deposition. Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables was done using a combination of forward and backward selection methods. The explained variance ranged from 10% to 53% depending on the species. Variables related to forest structure (basal area of the stand and relative size of the tree) contributed most to the explained variance, but environmental variables were important to account for spatial patterns. The type of environmental variables included differed greatly among species. Conclusions: The presented diameter increment models are the first of their kind that are applicable at the European scale. This is an important step towards the development of a new generation of forest development simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and applicable to a wider range of management systems than before. This allows European scale but detailed analyses concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etcinfo:eu-repo/semantics/publishedVersio

Coordination features of a hybrid scorpionate/phosphane ligand exemplified with iridium

Although the pentacoordinated complex [Ir{(allyl)B(CH2PPh2)(pz)2}(cod)] (1; pz=pyrazolyl, cod=1,5-cyclooctadiene), isolated from the reaction of [{Ir(μ-Cl)(cod)}2] with [Li(tmen)][B(allyl)(CH2PPh2)- (pz)2] (tmen=N,N,N′,N′-tetramethylethane-1,2-diamine), shows behavior similar to that of the related hydridotris(pyrazolyl)borate complex, the carbonyl derivatives behave in a quite different way. On carbonylation of 1, the metalmetal-bonded complex [(Ir{(allyl)B(CH2PPh2)(pz)2}CO)2(μ-CO)] (2) that results has a single ketonic carbonyl bridge. This bridging carbonyl is labile such that upon treatment of 2 with PMe3 the pentacoordinated IrI complex [Ir(CO){(pz)B(η2-CH2CHCH2)(CH2PPh2)(pz)}(PMe3)] (3) was isolated. Complex 3 shows a unique fac coordination of the hybrid ligand with the allyl group η2-bonded to the metal in the equatorial plane of a distorted trigonal bipyramid with one pyrazolate group remaining uncoordinated. This unusual feature can be rationalized on the basis of the electron-rich nature of the metal center. The related complex [Ir(CO){(pz)B(η2-CH2CHCH2)(CH2PPh2)(pz)}(PPh3)] (4) was found to exist in solution as a temperature-dependent equilibrium between the cis-pentacoordinated and trans square planar isomers with respect to the phosphorus donor atoms. Protonation of 3 with different acids is selective at the iridium center and gives the cationic hydrides [Ir{(allyl)B(CH2PPh2)(pz)2}(CO)H(PMe3)]X (X=BF4 (5), MeCO2 (6), and Cl (7)). Complex 7 further reacts with HCl to generate the unexpected product [Ir(CO)Cl{(Hpz)B(CH2PPh2)(pz)CH2CH(Me)}(PMe3)]Cl (9; Hpz=protonated pyrazolyl group) formed by the insertion of the hydride into the Ir-(η2-allyl) bond. In contrast, protonation of complex 4 with HCl stops at the hydrido complex [Ir{(allyl)B(CH2PPh2)(pz)2}(CO)H(PPh3)]Cl (8). X-ray diffraction studies carried out on complexes 2, 3, and 9 show the versatility of the hybrid scorpionate ligand in its coordination.Generous financial support from MEC/FEDER (Project CTQ2005-06807/BQU) and DGA (Research group E70) is gratefully acknowledged. J.A.C. thanks the Ministerio de Educación y Ciencia for a fellowship.Peer reviewe

Peripheral SH-functionalisation of carbosilane dendrimers including the synthesis of the model compound dimethylbis(propanethiol)silane and their interaction with rhodium complexes

Treatment of the allyl-containing compounds Me2Si(CH2CH[double bond, length as m-dash]CH2)2 and MeSi(CH2CH[double bond, length as m-dash]CH2)3 with thioacetic acid in the presence of AIBN gave Me2Si[(CH2)3SC(O)CH3]2 and MeSi[(CH2)3SC(O)CH3]3, respectively, which were reduced with LiAlH4 to the dithiols Me2Si[(CH2)3SH]2 (3) and MeSi[(CH2)3SH]3 (4). This protocol was applied to the first and second generations of the doubly and triply-branched carbosilane allyl dendrimers, Si[(CH2)3SiMe(CH2CH[double bond, length as m-dash]CH2)2]4 (G(1)allyl-8), Si[(CH2)3SiMe{(CH2)3SiMe(CH2CH[double bond, length as m-dash]CH2)2}2]4 (G(2)allyl-16), Si[(CH2)3Si(CH2CH[double bond, length as m-dash]CH2)3]4 (G(1)allyl-12), and Si[(CH2)3Si{(CH2)3Si(CH2CH[double bond, length as m-dash]CH2)3}3]4 (G(2)allyl-36) to give the corresponding SH functionalised surface dendrimers Si[(CH2)3SiMe(CH2CH2CH2SH)2]4 (G(1)SH-8), G(2)SH-16, G(1)SH-12, and G(2)SH-36. Reactions of 3 with [M(acac)(diolefin)] (M = Rh, Ir; diolefin = 1,5-cyclooctadiene, 2,5-norbornadiene) gave the compounds of the type [M2(µ-Me2Si[(CH2)3S]2)(diolefin)2]n. These diolefin complexes are octanuclear (n = 4) in solution while the complex [Rh2(µ-Me2Si[(CH2)3S]2)(cod)2]n (5) is tetranuclear in the solid state. The structure of 5, solved by X-ray diffraction methods, consists of a 20-membered metallomacrocycle formed by two dimethylbis(propylthiolate)silane moieties bridging four fragments Rh(cod) in a µ2 fashion through the sulfur atoms. Treatment of [Rh(acac)(CO)2] with 3 gave [Rh2(µ-Me2Si[(CH2)3S]2)(CO)4]n, which is a mixture of tetra (n = 2) and octanuclear (n = 4) complexes in a 2 : 1 ratio in solution, while the related complex [Rh2(µ-Me2Si[(CH2)3S]2)(CO)2(PPh3)2]2 is tetranuclear. Reactions of [Rh(acac)(L–L)] (L–L = cod, (CO)2, (CO)(PPh3)) with 4 and the dendrimers G(1)SH-8, G(2)SH-16, and G(1)SH-12, gave microcrystalline solids of formulae [Rh3(MeSi[(CH2)3S]3)(L–L)3]n, [Si[(CH2)3SiMe{(CH2)3SRh(cod)}2]4]n ([G(1)Rh(cod)-8]n), [Si[(CH2)3Si{(CH2)3SRh(cod)}3]4]n ([G(1)Rh(cod)-12]n), etc., which presumably are tridimensional coordination polymers.The financial support from Ministerio de Ciencia y Tecnología (MCyT(DGI)/FEDER) Project BQU2002-0074 is gratefully acknowledged. J. A. C. thanks Ministerio de Educación y Ciencia for a fellowship.Peer reviewe

Unprecedented hybrid scorpionate/phosphine ligand able to be anchored to carbosilane dendrimers

The synthesis of a novel hybrid pyrazolate/phosphine anionic ligand [CH2CHCH2B(CH2PPh2)(pz)2]- is described. Coordination of this ligand to metals in a fac tridentate fashion occurs in the complexes [CH2CHCH2B(CH2PPh2)(pz)2M(cod)], prepared by reactions of the lithium salt of the ligand with [M(μ-Cl)(cod)]2 (M = Rh, Ir). They are pentacoordinated, with the rhodium complex showing a distorted trigonal-bipyramidal structure in the solid state, as determined by X-ray diffraction methods. Furthermore, the ligand has been linked to the periphery of a carbosilane dendrimer, resulting in the polyanionic dendrimer [Li(TMED)]4[Si{(CH2)3SiMe2(CH2)3B(CH2PPh2)(pz)2}4], which leads further to the corresponding metallodendrimer with four rhodium atoms.The financial support from MCyT(DGI)/FEDER (Project BQU2002-0074) and MEC/FEDER (Project CTQ2005-06807/BQU) is gratefully acknowledged. J.A.C. thanks Ministerio de Educacion y Ciencia for a fellowship. V.H. thanks Akademisches Auslandsamt der Westfalischen Wilhelms, Universitat Munster, for an Erasmus fellowship.Peer reviewe