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The orientation of phosphate bridges as well as the VO6 octahedron arrangement determine the effectiveness of exchange pathways leading to specific magnetic properties. This was concluded in an analysis of the magnetic behavior of several oxovanadium(IV) phosphates which show magnetic diversity, due partly to the possible involvement of phosphate groups in the spin transfer between V(super IV) centers. These and previous results are part of a topological scheme leading to a magnetostructural correlation allowing predictions on the magnitude of magnetic interaction in related oxovanadium phosphates.

Chemical research has established a way of creating layered oxovanadium phosphate hydrates M(VOPO4)2.nH2O using Ba2+ cations and arsenate anions. A partial charge model and valence matching principle were used. X-ray single crystal data analysis is used to identify the barium lamellar derivative Ba(VOPO4)2.4H20. Structure determination analysis is discussed.

A synthetic approach to a V-P-O framework is reported based on the concept that the framework in the final solid is influenced by the properties of ionic aggregates in solution. A revised version of the partial charge model by Livage is applied to the synthesis of a reported oxovanadium phosphate and a novel V(IV)-Fe(III) bimetallic oxovanadium phosphate (H3N(CH2)2NH3)2(H3N(CH2)2NH2)(FeIII(H2O)2(VIVO)8(OH)4(HPO4)4(PO4)4).-4H2O. Both compounds have structural directing agents in the form of ethylenediamine.

A layer transition metal hypophosphite serves as host lattice for intercalation reactions. Several two-dimensional systems arise due to the low connectivity of pseudotetrahedral species and related anions. Water and pyridine intercalation processes are studied using thermal analysis, variable-temperature X-ray powder diffraction and spectroscopic techniques.

The synthesis and characterization of (eta5-C5H5)Fe(eta5-C5H4) CH=N(CH2)2N= CH(eta5-C5H4)Fe(eta5-C5H5), its related amine and the pentanuclear complex (Cu(Fc2L)2(NO3)2).2CH3OH were reported. The pentanuclear complex consisted of (Cu(Fc2L)2(NO3)2) neutral units and methanol molecules as analyzed by single-crystal X-ray crystallography. Potentiometric titrations were performed to investigate the reactions of (eta5-C5H5)Fe(eta5- C5H4)CH2NH(CH2)2NHCH2(eta5-C5H4)Fe(eta5-C5H5),FcL with copper(II).

Nanoparticle–cell–nanoparticle communication by stigmergy was demonstrated using two capped nanodevices. The first community of nanoparticles (i.e.S(RA)IFN) is loaded with 9-cis-retinoic acid and capped with interferon-γ, whereas the second community of nanoparticles (i.e.S(sulf)PIC) is loaded with sulforhodamine B and capped with poly(I:C). The uptake of S(RA)IFN by SK-BR-3 breast cancer cells enhanced the expression of TLR3 receptor facilitating the subsequent uptake of S(sulf)PIC and cell killing. [ABSTRACT FROM AUTHOR]

This work reports the synthesis, characterization, and sensing behavior of a hybrid nanodevice for the detection of the potent abuse drug 25I‐NBOMe. The system is based on mesoporous silica nanoparticles, loaded with a fluorescent dye, functionalized with a serotonin derivative and capped with the 5‐HT2A receptor antibody. In the presence of 25I‐NBOMe the capping antibody is displaced, leading to pore opening and rhodamine B release. This delivery was ascribed to 5‐HT2A receptor antibody detachment from the surface due to its stronger coordination with 25I‐NBOMe present in the solution. The prepared nanodevice allowed the sensitive (limit of detection of 0.6 μm) and selective recognition of the 25I‐NBOMe drug (cocaine, heroin, mescaline, lysergic acid diethylamide, MDMA, and morphine were unable to induce pore opening and rhodamine B release). This nanodevice acts as a highly sensitive and selective fluorometric probe for the 25I‐NBOMe illicit drug in artificial saliva and in sweets. [ABSTRACT FROM AUTHOR]

A detailed study on the behavior of a pH-driven and anion-controlled nano-supramolecular gate-like ensemble obtained by anchoring suitable polyamines on the pore outlets of mesoporous materials of the type MCM-41 is reported. The results provide insight into the pH-controlled open/close mechanism attributed to hydrogen-bonding interactions between amines (open-gate) and Coulombic repulsion between ammonium groups (closed-gate).

Here, a new bio‐inspired nanoarchitectonics approach for the design of optical probes is presented. It is based on nanodevices that combine 1) an enzymatic receptor subunit, 2) a signaling subunit (consisting of a labeled reporter attached to a silica surface), and 3) a mechanism of communication between the two sites based on the production of chemical messengers by the enzymatic subunit, which induces the detachment of the reporter molecules from the silica surface. As a proof of concept, a urea nanosensor based on the release of Alexa‐Fluor‐647‐labeled oligonucleotide from enzyme‐functionalized Janus gold–mesoporous‐silica nanoparticles (Au–MSNPs) was developed. The Janus particles were functionalized on the silica face with amino groups to which the labeled oligonucleotides were attached by electrostatic interactions, whereas the gold face was used for grafting urease enzymes. The nanodevice was able to release the fluorescent oligonucleotide through the enzyme‐mediated hydrolysis of urea to ammonia and the subsequent deprotonation of amino groups on the silica face. This simple nanodevice was applied for the fluorometric detection of urea in real human blood samples and for the identification of adulterated milk. Given the large variety of enzymes and reporter species that could be combined, this is a general new paradigm that could be applied to the design of a number of optical probes for the detection of target analytes. Designing biosensors: A new paradigm for the design of optical sensors based on nanodevices incorporating an enzymatic receptor subunit and a hybrid signaling subunit that communicate through chemical messengers is presented. As a proof of concept, a urea nanosensor based on the release of an oligonucleotide labeled with Alexa Fluor 647 from urease‐functionalized Janus gold–mesoporous‐silica nanoparticles (Au–MSNPs) was developed. [ABSTRACT FROM AUTHOR]

Probe 1, which contains an anilinopyridine chromophore and an aza-oxa macrocyclic subunit, presented an absorption band centered at 340 nm in acetonitrile. Addition of Fe(III), Cr(III) and Hg(II) induced the growth of a new absorption band at 430 nm (with color change from colorless to yellow), whereas in the presence of Cu(II), Zn(II) and Pb(II), less marked changes were observed. The color changes observed upon addition of Fe(III), Cr(III) and Hg(II) were ascribed to the formation of 1:1 stoichiometry complexes with probe 1. Coordination of Fe(III), Cr(III) and Hg(II) with the pyridine fragment of 1 induced an enhancement of the charge transfer character accompanied with a marked bathochromic shift that was reflected in a color change from colorless to yellow. The strength of the interaction between probe 1 and Fe(III) cation was modulated upon interaction with anions. Of all the anions tested, only cyanide was able to induce the bleaching of the yellow 1·Fe(III) complex solution. This bleaching was ascribed to the formation of 1·Fe(III)-CN complex that restored, to some extent, the optical features of the free probe allowing the chromogenic sensing of cyanide. Besides, 1·Fe(III) complex was used to detect cyanide in acetonitrile-water 90:10 v/v mixtures with good recoveries. [ABSTRACT FROM AUTHOR]

Abstract: Apoptotic signaling pathways are altered in numerous pathologies such as cancer. In this scenario, caspase‐9/PP2Acα interaction constitutes a key target with pharmacological interest to re‐establish apoptosis in tumor cells. Very recently, a short peptide (C9h) known to disrupt caspase‐9/PP2Acα interaction with subsequent apoptosis induction was described. Here, we prepared two sets of mesoporous silica nanoparticles loaded with safranin O (S2) or with C9h peptide (S4) and functionalized with ϵ‐polylysine as capping unit. Aqueous suspensions of both nanoparticles showed negligible cargo release whereas in the presence of pronase, a marked delivery of safranin O or C9h was observed. Confocal microscopy studies carried out with HeLa cells indicated that both materials were internalized and were able to release their entrapped cargos. Besides, a marked decrease in HeLa cell viability (ca. 50 %) was observed when treated with C9h‐loaded S4 nanoparticles. Moreover, S4 provides peptide protection from degradation additionally allowing for a dose reduction to observe an apoptotic effect when compared with C9h alone or in combination with a cell‐penetrating peptide (i.e., Mut3DPT‐C9h). Flow cytometry studies, by means of Annexin V‐FITC staining, showed the activation of apoptotic pathways in HeLa as a consequence of S4 internalization, release of C9h peptide and disruption of caspase‐9/PP2Acα interaction. [ABSTRACT FROM AUTHOR]

Magnetic micro-sized mesoporous silica particles were used for the preparation of a gated material able to release an entrapped cargo in the presence of an azo-reducing agent and, to some extent, at acidic pH. The magnetic mesoporous microparticles were loaded with safranin O and the external surface was functionalized with an azo derivative 1 (bearing a carbamate linkage) yielding solid S1. Aqueous suspensions of S1 at pH 7.4 showed negligible safranin O release due to the presence of the bulky azo derivative attached onto the external surface of the inorganic scaffold. However, in the presence of sodium dithionite (azoreductive agent), a remarkable safranin O delivery was observed. At acidic pH, a certain safranin O release from S1 was also found. The pH-triggered safranin O delivery was ascribed to the acid-induced hydrolysis of the carbamate moiety that linked the bulky azo derivatives onto the mesoporous inorganic magnetic support. The controlled release behavior of S1 was also tested using a model that simulated the gastro intestinal tract. [ABSTRACT FROM AUTHOR]

Aptamers have been used as recognition elements for several molecules due to their great affinity and selectivity. Additionally, mesoporous nanomaterials have demonstrated great potential in sensing applications. Based on these concepts, we report herein the use of two aptamer-capped mesoporous silica materials for the selective detection of ochratoxin A (OTA). A specific aptamer for OTA was used to block the pores of rhodamine B-loaded mesoporous silica nanoparticles. Two solids were prepared in which the aptamer capped the porous scaffolds by using a covalent or electrostatic approach. Whereas the prepared materials remained capped in water, dye delivery was selectively observed in the presence of OTA. The protocol showed excellent analytical performance in terms of sensitivity (limit of detection: 0.5-0.05 n m), reproducibility, and selectivity. Moreover, the aptasensors were tested for OTA detection in commercial foodstuff matrices, which demonstrated their potential applicability in real samples. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles loaded with rhodamine B and capped with a bisphenol A aptamer were used for the selective and sensitive detection of this lethal chemical. The pores of the nanoparticles are selectively opened in the presence of bisphenol A (through its selective coordination with the aptamer) with subsequent rhodamine B delivery. With this capped material a limit of detection as low as 3.5 μ m of bisphenol A was measured. [ABSTRACT FROM AUTHOR]

A nanoporous anodic alumina (NAA)-based sensor system for the detection of Mycoplasma was developed through the implementation of "molecular gates" selective to the presence of this bacterium. The capped support showed a negligible cargo release, while presence of Mycoplasma genomic DNA resulted in the release of rhodamine B fluorescent dye. This sensor system presents a limit of detection of 20 genomic DNA copies .μL-1 and was applied to the detection of Mycoplasma bacteria in competitive environments, such as culture cell media. [ABSTRACT FROM AUTHOR]

Within nanotechnology, gold and silver nanostructures have unique physical, chemical, and electronic properties [1,2], which make them suitable for a number of applications. Moreover, biosynthetic methods are considered to be a safer alternative to conventional physicochemical procedures for both the environmental and biomedical applications, due to their eco-friendly nature and the avoidance of toxic chemicals in the synthesis. For this reason, employing bio routes in the synthesis of functionalized silver nanoparticles (FAgNP) have gained importance recently in this field. In the present study, we report the rapid synthesis of FAgNP through the extract of pepino (Solanum muricatum) leaves and employing microwave oven irradiation. The core-shell globular morphology and characterization of the different shaped and sized FAgNP, with a core of 20-50 nm of diameter is established using the UV-Visible spectroscopy (UV-vis), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Zeta potential and dynamic light scanning (DLS) studies. Moreover, cytotoxic studies employing HeLa (human cervix carcinoma) cells were undertaken to understand FAgNP interactions with cells. HeLa cells showed significant dose dependent antiproliferative activity in the presence of FAgNP at relatively low concentrations. The calculated IC50 value was 37.5 µg/mL, similar to others obtained for FAgNPs against HeLa cells. [ABSTRACT FROM AUTHOR]

We describe herein a Toll-like receptor 3 (TLR3) targeting delivery system based on mesoporous silica nanoparticles capped with the synthetic double stranded RNA polyinosinic-polycytidylic acid (poly(I:C)) for controlled cargo delivery in SK-BR-3 breast carcinoma cells. Our results show that poly(I:C)-conjugated nanoparticles efficiently targeted breast cancer cells due to dsRNA-TLR3 interaction. Such interaction also triggered apoptotic pathways in SK-BR-3, significantly decreasing cells viability. Poly(I:C) cytotoxic effect in breast carcinoma cells was enhanced by loading nanoparticles′ mesopores with the anthracyclinic antibiotic doxorubicin, a commonly used chemotherapeutic agent. [ABSTRACT FROM AUTHOR]

The design of comparatively simple and modularly configurable artificial systems able to communicate through the exchange of chemical messengers is, to the best of our knowledge, an unexplored field. As a proof-of-concept, we present here a family of nanoparticles that have been designed to communicate with one another in a hierarchical manner. The concept involves the use of capped mesoporous silica supports in which the messenger delivered by a first type of gated nanoparticle is used to open a second type of nanoparticle, which delivers another messenger that opens a third group of gated nanoobjects. We believe that the conceptual idea that nanodevices can be designed to communicate with one another may result in novel applications and will boost further advances towards cooperative systems with complex behavior as a result of the communication between simple abiotic individual components. [ABSTRACT FROM AUTHOR]

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Three new hybrid gated mesoporous materials ( SN3-1, SNH2-2, and SN3-3) loaded with the dye [Ru(bipy)3]2+ (bipy=bipyridine) and capped with different tetrathiafulvalene (TTF) derivatives (having different sizes and shapes and incorporating different numbers of sulfur atoms) have been prepared. The materials SN3-1 and SN3-3 are functionalized on their external surfaces with the TTF derivatives 1 and 3, respectively, which were attached by employing the 'click' chemistry reaction, whereas SNH2-2 incorporates the TTF derivative 2, which was anchored to the solid through an amidation reaction. The final gated materials have been characterized by standard techniques. Suspensions of these solids in acetonitrile showed 'zero release', most likely because of the formation of dense TTF networks around the pore outlets. The release of the entrapped [Ru(bipy)3]2+ dye from SN3-1, SNH2-2, and SN3-3 was studied in the presence of selected explosives (Tetryl, TNT, TNB, DNT, RDX, PETN, PA, and TATP). SNH2-2 showed a fairly selective response to Tetryl, whereas for SN3-1 and SN3-3 dye release was found to occur with Tetryl, TNT, and TNB. The uncapping process in the three materials can be ascribed to the formation of charge-transfer complexes between the electron-donating TTF units and the electron-accepting nitroaromatic explosives. Finally, solids SNH2-2 and SN3-1 have been tested for Tetryl detection in soil with good results, pointing toward a possible use of these or similar hybrid capped materials as probes for the selective chromo-fluorogenic detection of nitroaromatic explosives. [ABSTRACT FROM AUTHOR]

Blue with CO2! A new approach for the chromogenic sensing of carbon dioxide using silica nanoparticles functionalized with amino and thiol moieties has been reported. The presence of CO2 in suspensions of the hybrid silica nanoparticles controlled the access of a squaraine dye to the surface of the nanoparticles resulting in a chromogenic response (see figure). [ABSTRACT FROM AUTHOR]

Come and gate it: DNA‐capped mesoporous silica nanoparticles loaded with a dye are used to detect the common contaminate Mycoplasma in real contaminated cell‐culture media without needing polymerase chain reaction (PCR) techniques, at a detection limit in the range of 70 DNA genome copies μL−1. [ABSTRACT FROM AUTHOR]

Mit DNA verschlossene und mit Farbstoff beladene mesoporöse Siliciumdioxid ‐ Nanopartikel wurden zum Nachweis von Mycoplasma bis zu einer Nachweisgrenze von ca. 70 genomischen DNA ‐ Kopien pro μL in real kontaminierten Zellkulturmedien ohne die Hilfe von PCR ‐ Techniken eingesetzt. [ABSTRACT FROM AUTHOR]

The preparation of a new capped silica mesoporous material, Rh-Azo-S, for on-command delivery applications in the presence of target enzymes is described. The material consists of nanometric mesoporous MCM-41-like supports loaded with Rhodamine B and capped with an azopyridine derivative. The material was designed to show 'zero delivery' and to display a cargo release in the presence of reductases and esterases, which are usually present in the colon, mainly due to intestinal microflora. The opening and cargo release of Rh-Azo-S in vitro studies were assessed and seen to occur in the presence of these enzymes, whereas no delivery was noted in the presence of pepsine. Moreover, Rh-Azo-S nanoparticles were used to study controlled Rhodamine B dye delivery in intracellular media. HeLa cells were employed for testing the 'non'-toxicity of nanoparticles. Moreover, delivery of the dye in these cells, through internalization and enzyme-mediated gate opening, was confirmed by confocal microscopy. Furthermore, the nanoparticles capped with the Azo group and loaded with a cytotoxic camptothecin ( CPT) were also prepared (solid CPT-Azo-S) and used as delivery nanodevices in HeLa cells. When this solid was employed, the cell viability decreased significantly due to internalization of the nanoparticles and delivery of the cytotoxic agent. [ABSTRACT FROM AUTHOR]

Bis-functionalised silica surfaces have been designed in order to develop selective and sensitive probes for the chromo-fluorogenic detection of certain guests. The designed system consists of a siliceous support bis-functinalised with thiol and polyamine groups. Thiol groups are suitable reactive centres (R) that are know to react with squaraine dyes (D) inducing bleaching, whereas polyamines act as host sites (H) able to coordinate certain target guests (G). In the absence of G, the reactive groups (R) react with the dye resulting in a bleaching of the solution. On the contrary, the presence of certain guest (G) results in a control of the reaction kinetic between R and D and eventually in a complete reaction inhibition. Different functionalised solids S1xwere prepared by reaction of the siliceous surface with different concentrations of mercaptopropyltrimethoxysilane (MPTS) and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (N3TS). The final materials (solids S1ato S1d) were characterized employing standard procedures. In a first step the reactivity of the signaling dye D (squaraine I) with the reactive centre R (thiol groups) was studied as a function of the pH using solid S1dthat showed a most suitable response. At pH 7 and pH 5 there was a quick reaction between the squaraine and the thiol groups on the surface. On the contrary this reaction is significantly slower at pH 3 due to the different degree of protonation of the amines as a function of the pH. Additionally the reaction of S1dwith the squaraine Ihas been studied in the presence of a range of inorganic anions with different structural dimensions and charges, including chloride, perchlorate, nitrate, sulfate, phosphate and pyrophosphate. At pH 3 the reaction of the dye with the thiol groups is still effective in the presence of chloride and perchlorate, but the reaction is highly inhibited in the presence of the anions nitrate, sulfate, phosphate and pyrophosphate. At pH 7 the squaraine Ireacts very fast with the thiol groups in the presence of all the anions studied. In contrast, at pH 5 only pyrophosphate is able to inhibit, to a certain extent, the reaction of the squaraine with the thiols, resulting in a selective chromo-fluorogenic detection of this anion in pure water. Finally, the observed behaviour was discussed in terms of both, the kinetic rates of the reaction between the thiol and the squaraine groups and the thermodynamic interaction reaction between the anions and the polyamine moieties. [ABSTRACT FROM AUTHOR]