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The aim of this study is to determine the efficiency of loading and release of several zwitterionic, neutral, anionic and cationic dyes into/from mesoporous nanoparticles to find the optimum loading and release conditions for their application in detection protocols. The loading is carried out for MCM-41 type silica supports suspended in phosphate-buffered saline (PBS) buffer (pH 7.4) or in acetonitrile, involving the dyes (rhodamine B chloride, rhodamine 101 chloride, rhodamine 101 perchlorate, rhodamine 101 inner salt, meso-(4-hydroxyphenyl)-boron–dipyrromethene (BODIPY), sulforhodamine B sodium salt and fluorescein 27). As a general trend, rhodamine-based dyes are loaded with higher efficiency, when compared with BODIPY and fluorescein dyes. Between the rhodamine-based dyes, their charge and the solvent in which the loading process is carried out play important roles for the amount of cargo that can be loaded into the materials. The delivery experiments carried out in PBS buffer at pH 7.4 reveal for all the materials that anionic dyes are more efficiently released compared to their neutral or cationic counterparts. The overall best performance is achieved with the negatively charged sulforhodamine B dye in acetonitrile. This material also shows a high delivery degree in PBS buffer.

The synthesis, characterization, and application of mesoporous materials containing boron–dipyrromethene (BODIPY) moieties that allow the sensitive and selective detection of HgII in aqueous environments by fluorescence enhancement is reported. For this purpose, BODIPY dye I containing a thia‐aza crown ether receptor as the fluorescent probe for the detection of HgII in aqueous environments is encapsulated into mesoporous materials to avoid self‐quenching or aggregation in water. Determination of HgII is accomplished within a few seconds with high selectivity and sensitivity, reaching a limit of detection of 12 ppt. The determination of trace amounts of HgII in natural waters and in fish extracts is demonstrated by using our sensing material. The incorporation of the material into several μ‐PAD strips yields a portable, cheap, quick, and easy‐to‐handle tool for trace HgII analysis in water.

[EN] A novel mesoporous silica material containing boron-dipyrromethene (BODIPY) moieties (I) is employed for the detection of nerve agent simulants (NASs) and the organophosphate nerve or chemical warfare agents (CWAs) Sarin (GB), Soman (GD), and Tabun (GA) in aqueous environments. The reactive BODIPY dye with an optimum positioned hydroxyl group undergoes acylation reactions with phosph(on)ate substrates, yielding a bicyclic ring. Due to aggregation of the dyes in water, the sensitivity of the free dye in solution is very low. Only after immobilization of the BODIPY moieties into the silica substrates is aggregation inhibited and a sensitive determination of the NASs diethyl cyanophosphonate (DCNP), diethyl chlorophosphate (DCP) and diisopropyl fluorophosphate (DFP) possible. The signaling mode is a strong quenching of the fluorescence, reaching LODs in the pM range. The best performing hybrid material was singled out from a library of hybrid silicas varying in morphology and surface functionalization. The response to actual CWAs such as GB, GD, and GA has also been tested, offering similar behavior as for the simulants. The proposed reaction mechanism has been verified by investigation of other model materials, containing for instance BODIPY moieties without an optimum hydroxyl group (III) or a BODIPY dye with an all-aliphatic counterpart (IV). The latter can only form a monocyclic reaction product, showing much less reactivity as I. Assays with other possible competitors have been additionally carried out, showing favorably low cross-reactivities. Finally, the determination of NASs in several natural waters has been demonstrated. (C) 2017 Elsevier B.V. All rights reserved., Financial support from the Alexander von Humboldt Foundation, Germany's Federal Ministry for Economic Affairs and Energy, the Generalitat Valenciana (Project PROMETEOII/2014/047), the Spanish Government and European FEDER funds (Project MAT2015-64139-C4) is gratefully acknowledged. We thank S. Selve (Technical University Berlin) for TEM images, A. Zehl (Humboldt University Berlin) for elemental analysis, D. Pfeifer and C. Jager (BAM, Div. 1.3) for NMR support, A. Zimathies (BAM, Div. 1.3) for N2 adsorption/desorption measurements and T. Fischer (BAM, Div. 1.9) for support with the fluorescence decay measurements.

[EN] The synthesis of capped mesoporous silica nanoparticles (MSN) conjugated with an antibody (AB) as a gatekeeper has been carried out in order to obtain a delivery system able to release an entrapped cargo (dye) in the presence of a target molecule (antigen) to which the conjugated antibody binds selectively. In particular, MSN loaded with rhodamine B and functionalized on the external surface with a suitable derivative of N-(t-butyl)- 3-oxo-(5a,17b)-4-aza-androst-1-ene-17-carboxamide (finasteride) have been prepared (S1). The addition of polyclonal antibodies against finasteride induced capping of the pores due to the interaction with the anchored hapten-like finasteride derivative to give a MSN¿hapten¿AB nanoparticle S1-AB. It was found that the addition of capped material S1-AB to water solutions containing finasteride resulted in displacement of the antibody, pore uncapping and entrapped-dye release. The response of the gated material is highly selective, and only finasteride, among other steroids, was able to induce a significant uncapping process. Compared with finasteride, the finasteride metabolite was able to release 17% of the dye, whereas the exogen steroids testosterone, metenolone and 16-b-hydroxystanozolol only induced very little release of rhodamine B (lower than 10%) from aqueous suspensions containing sensing solid S1-AB. A detection limit as low as 20 ppb was found for the fluorimetric detection of finasteride. In order to evaluate a possible application of the material for label-free detection of finasteride, the capped material was isolated and stored to give final sensing solid S1-AB-i. It was found to display a similar behavior towards finasteride as to that shown by freshly prepared S1-AB; even after a period of two months, no significant loss of selectivity or sensitivity was noted. Moreover, to study the application for the detection of finasteride in biological samples, this ¿aged¿ material, S1-AB-i, was tested using commercially available blank urine as matrix. Samples containing 70 and 90% blank urine were spiked with a defined amount of finasteride, and the concentration was determined using capped S1-AB-i. Recovery ranges from 94% to 118% were reached., Financial support from the Spanish Government (project MAT2009-14564-C04-01) and the Generalitat Valenciana (Spain) (projects PROMETEO/2009/016 and PROMETEO/2010/008) is gratefully acknowledged. E. C. thanks the Minesterio de Ciencia e Innovacion (MICINN, Spain) for her fellowship.

The Front Cover shows how differences in color and fluorescence on a test strip can be easily read out with a mobile device. Two reference spots frame the sensitive spot that indicates the presence of trace amounts of HgII below the threshold in a natural water sample. This dipstick contains a hybrid material that combines boron‐dipyrromethene (BODIPY) probes sterically loaded into specifically tailored mesoporous silica particles, allowing for ultrasensitive HgII detection through enhanced fluorescence within a few seconds. More information can be found in the Full Paper by K. Rurack and co‐workers on page 957 in Issue 12, 2018 (DOI: https://doi.org/10.1002/open.201800111).

Test strips that in combination with a portable fluorescence reader or digital camera can rapidly and selectively detect chemical warfare agents (CWAs) such as Tabun (GA), Sarin (GB), and Soman (GD) and their simulants in the gas phase have been developed. The strips contain spots of a hybrid indicator material consisting of a fluorescent BODIPY indicator covalently anchored into the channels of mesoporous SBA silica microparticles. The fluorescence quenching response allows the sensitive detection of CWAs in the mu g m(-3) range in a few seconds., Financial support from the Alexander von Humboldt Foundation, the German Federal Ministry for Economic Affairs and Energy, European FEDER funds (MAT2012-38429-C04), the Generalitat Valenciana (PROMETEOII/2014/047), and the Spanish Government is gratefully acknowledged. We thank S. Selve (Technical University Berlin) for TEM images, A. Zehl (Humboldt University Berlin) for elemental analysis, D. Pfeifer (BAM, Div. 1.3) for NMR, A. Zimathies (BAM 1.3) for N2 adsorption/desorption, S. Ewald and A. Lehmann (BAM 1.5 & 1.8) for MS support, and T. Fischer (BAM 1.9) for support with the fluorescence decay measurements.

This critical review is focused on examples reported in the year 2009 dealing with the design of chromogenic and fluorogenic chemosensors or reagents for anions (264 references).

[EN] Antibodygated MSNs that are loaded with a rhodamine dye and that can be used for the determination of the presence of peroxide-based explosive TATP with a lateral-flow fluorescence reader have been designed and prepared, thereby allowing for detection limits in the lower ppb range. The mechanism of the detection relies on a displacement of the antibody from the surface of the hybrid material because of highly affine antibody-TATP interactions, which release a much larger number of entrapped dye molecules from the pores than antibodies are displaced. The high selectivity of the antibody is retained in the gated material, thus allowing for a remarkable discrimination against H2O2. System design and optimization led to straightforward integration into a lateral-flow assay without further treatment or conditioning of the test strips while guaranteeing fast overall assay times of minus or equal 10 min. Moreover, besides showing a remarkable robustness, the inherent architecture of the assay relies on a single-step immunochemical reaction, that is, it can dispense with secondary (labeled) antibodies and enables ratiometric signal assessment in the presence of the analyte by simple comparison of the fluorescence signals in two zones. Because of the modularity of the approach, the concept is easily generalizable and applicable for many small-molecule analytes. For instance, assays can be imagined that contain various hybrids of S1-AB(n) type, for which each material capped with a certain antibody is loaded with a different dye, thus envisioning multiplexed analysis with such simple assays., Financial support from the Spanish Government (MAT2009-14564-C04-01), the Generalitat Valenciana (PROMETEO/2009/016), the Innovationsfonds (BAM/Bundesministerium fur Wirtschaft und Technologie), and BAM's PhD Program (M.A.W.) is gratefully acknowledged. E.C. thanks the Ministerio de Educacion for a fellowship. We are indebted to J. Schenk, BAM-1.0, for help with the piezo dispenser and S. Fischer and W. Weigel, Scienion AG, Berlin, for support with the spotter.

Hybrid nanoparticles with a large specific surface area are a particularly exciting vehicle for delivery applications. Such highly porous or container-like structures, usually prepared from silica and frequently from gold, can incorporate a large number of chemical substances such as drug and/or indicator molecules. When equipped with a chemically or physically addressable gating function at the openings of the voids, the release of the cargo can be controlled at will. Because many more molecules can be stored as cargo in the pores of the support than there are functional groups as anchoring sites for the gating entities attached to the outer surface (for efficient pore capping), the systems possess inherent features of (signal) amplification. The present article will introduce various design strategies for different types of physical (light, temperature, magnetism) and chemical (pH, metal ions, anion, small organic molecules, enzymes) stimuli in connection with drug and indicator release. We will highlight exciting aspects of combining both features in theranostic applications and will stress which requirements still have to be met by many of the systems to be readily applicable in a sensory context., Financial support from the Innovationsfonds (BAM/Bundesministerium fur Wirtschaft und Technologie), the Spanish Government (project MAT2012-38429-C04-01) and the Generalitat Valenciana (project PROMETEO/2009/016) is gratefully acknowledged.

The present study reports a novel approach for the chromogenic sensing of CO2 using silica nanoparticles N1 functionalized with amino and thiol moieties. The reaction of CO2 present in air with the hybrid silica nanoparticles controlled the access of a squaraine dye to the surface of nanoparticles, due to formation of carbamates between amino groups and carbon dioxide. This competitive reaction results in a simple chromogenic response to CO2. By using these bifunctionalized nanoparticles CO2 detection was achieved using suspensions of N1 in phosphate buffer or by using N1 directly in contact with air containing CO2. The use of nanoparticles that can be easily functionalized with two or more individual groups that are able to react with dyes and CO2, and the possible use of a wide range of different dyes (for signalling), makes this approach highly appealing and versatile for the design of chromo¿fluorogenic dosimeters for the evaluation of the accumulative exposure to CO2 in different environments, Financial support from the Spanish Government (project MAT2012-38429-C04-01) and the Generalitat Valencia (project PROMETEO/2009/016) is gratefully acknowledged. A. A. thanks the Generalitat Valencia for a Santiago Grisolia fellowship. M. E. M. is grateful to the Spanish Ministerio de Ciencia e Innovacion for an FPU grant.

A new chromo-fluorogenic sensing protocol for anionic surfactants in aqueous environments using silica functionalised nanoparticles containing imidazolium and thiol groups has been developed. © 2011 The Royal Society of Chemistry., Financial support from the Spanish Government (project MAT2009-14564-C04-01) and the Generalitat Valencia (project PROMETEO/2009/016) is gratefully acknowledged. E. C. and C. G. thank the MICINN and the UPV for fellowships.