Il lavoro descritto in questo documento è stato sostenuto da una sovvenzione da parte del Fondo per l&#39;Innovazione CII-HK / PolyU. Ulteriore supporto è stato fornito dal Piano di Shenzhen Pavone (KQTD2015071616442225) e il governo cinese programma &quot;Mille Talent&quot; (Y62HB31601). Inoltre, l&#39;aiuto da parte del Dipartimento di Biologia Applicata e Tecnologia Chimica del Politecnico di Hong Kong e l&#39;Istituto Politecnico di Hong Kong di Ricerca per lo Sviluppo Urbano Sostenibile (RISUD) è apprezzato.

1. Trattamento di HGM <ol><li> Posizionare il HGM in un bicchiere da 500 mL con 200 ml di alcool assoluto; la bassa densità di ininterrotta HGM induce a sospendere in alcool, ma perché la densità di rotture HGM è maggiore di quello dell&#39;alcool, precipita nella soluzione. Dopo 30 min, raccogliere il HGM sospesa con un cucchiaio pulito ed asciutto a 80 ° C in un forno per ulteriore applicazione. </li></ol> 2. Sintesi di MCHGM <ol><li> Porre 5 g di ininterrotta HGM, 47,5 mL di etanolo e 2,5 ml di acqua DI in un pallone a tre colli. Mescolare utilizzando un mescolatore a 400 giri / min per 20 min (premiscelazione). </li><li> Mescolare 15 g del TBT, 1 g di PFOTES, e 30 mL di alcol assoluto in un becher da 200 ml. Versare la miscela in un imbuto a pressione costante. </li><li> Inserire l&#39;imbuto a pressione costante in uno dei fori del pallone a tre colli. Goccia la miscela contenuta nell&#39;imbuto a pressione costante nel pallone a tre colli ad una velocità di1 goccia ogni 7 s, che si ottiene regolando la valvola dell&#39;imbuto pressione costante. Continuare la reazione per 3 ore. </li><li> Versare il composto dal pallone a tre colli in un reattore idrotermale. Mettere il reattore sigillato in un manicotto di acciaio adatto in un forno a 180 ° per 6 h. NOTA: Assicurarsi che il reattore ha una copertura adeguata. Dopo che è coperto, mettere il reattore nel manicotto di acciaio. Il manicotto deve essere sigillato con un coperchio. </li><li> Dopo che la reazione è terminata, raccogliere i campioni in sospensione nel reattore idrotermale con un grande cucchiaio. Essiccare i campioni a 80 ° C per 4 ore per ottenere MCHGM. </li></ol> 3. Sintesi di F-SCHGM <ol><li> Aggiungere 5 g di ininterrotta HGM, 47,5 mL di etanolo assoluto, e 2,5 ml di acqua DI ad un pallone a tre colli. Mescolare utilizzando un mescolatore a 400 giri / min per 20 min (premiscelazione). Mescolare 1 g di PFOTES e 30 mL di etanolo assoluto in un becher da 200 ml. Trasferire il PFOTES e assoluta emiscela thanol ad un imbuto a pressione costante. </li><li> Inserire l&#39;imbuto a pressione costante nel pallone a tre colli. Goccia la miscela contenuta nell&#39;imbuto a pressione costante nel pallone a tre colli ad una velocità di 1 goccia per 7 s. Lasciate che la reazione di una durata di 3 ore. </li><li> Trasferire il composto dal pallone a tre colli da un reattore idrotermale. Mettere il reattore sigillato in un forno a 180 ° per 6 h. Dopo che la reazione è terminata, raccogliere i campioni in sospensione nel reattore idrotermale con un grande cucchiaio. Essiccare i campioni a 80 ° C per 4 h per ottenere F-SCHGM. </li></ol> 4. Sintesi di Ti-SCHGM <ol><li> Porre 5 g di ininterrotta HGM, 47,5 mL di etanolo assoluto, e 2,5 mL di acqua deionizzata in un pallone a tre colli. Mescolare a 400 giri / min per 20 min (pre-miscelazione). Mescolare 15 g di OTC e 30 mL di etanolo assoluto in un becher da 200 ml. Trasferire il TBT e miscela di etanolo assoluto ad un imbuto a pressione costante. </li><li> Inserire le costanti-presAssicurarsi imbuto nel pallone a tre colli. Goccia la miscela nell&#39;imbuto a pressione costante nel pallone a tre colli ad una velocità di 1 goccia per 7 s. Lasciate che la reazione di una durata di 3 ore. </li><li> Trasferire il composto dal pallone a tre colli da un reattore idrotermale. Mettere il reattore sigillato in un forno a 180 ° per 6 h. Raccogliere i campioni nel reattore idrotermale dopo la reazione è terminata. Essiccare i campioni a 80 ° C per 4 h per ottenere Ti-SCHGM. </li></ol> 5. Caratterizzazioni <ol><li> Condurre caratterizzazioni XRD su tutti i campioni. Raccogliere i dati utilizzando un sistema polivalente diffrazione di raggi X è molto versatile con Cu Ka radiazioni (λ = 0,15,406 mila nm) e una 2θ che varia da 10 ° a 80 °. </li><li> Acquisire microscopio elettronico a scansione 20, 21 immagini dopo spruzzando i campioni con oro. Durante le prove SEM, conduce l&#39;EDS è su un&#39;area specifica. </li><li> misurare laangolo di contatto utilizzando un contatto angolo goniometro 22; il volume delle gocce d&#39;acqua dovrebbe essere di 10 microlitri. </li><li> Misurare l&#39;angolo di scivolamento 23 cambiando l&#39;angolo di inclinazione della superficie. Minimizzare l&#39;angolo finché la goccia d&#39;acqua può semplicemente scivolare giù. <ol><li> Bastone nastro biadesivo su una lastra di vetro (dimensioni: 26 mm x 76 mm x 2 mm). Usando un cucchiaio, posizionare uniformemente le polveri (F-SCHGM o MCHGM) sul nastro. Utilizzando un iniettore, aggiungere una goccia d&#39;acqua (volume: 0,05 mL) alla superficie della polvere. </li><li> Mettere la lastra di vetro sulla piattaforma del motore del goniometro contatto angolo. Inclinare la lastra di vetro inclinando la piattaforma motore a una velocità di 1 ° / s. Arrestare il motore quando la goccia d&#39;acqua inizia a scorrere; l&#39;angolo di inclinazione è l&#39;angolo di scorrimento. </li></ol></li><li> Misurare le spettri di riflettività utilizzando uno spettrofotometro 24. NOTA: La lunghezza d&#39;onda è da 450 nm a 2.550 nm. </li><li> Misurare la conducibilità termica di tutti i campioniutilizzando un misuratore di conducibilità termica 25. </li></ol>

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The authors have nothing to disclose.

In questo manoscritto, il passo critico nel protocollo è il processo idrotermale. Essa influenza la formazione di TiO 2, la riflettività finale, e il superhydrophobicity. Il controllo della temperatura e tempo di reazione sono anche abbastanza significativi. Se le condizioni di reazione cambiano, i prodotti finali possono essere viziata. Questo metodo fornisce un modo semplice per sintetizzare superhydrophobic e altamente IR-riflettente HGM in un&#39;unica fase. Nella ricerca pr...

microsfere cave di vetro (HGM) sono materiali inorganici di dimensioni variabili da 10 a 100 um. Essi dimostrano molte caratteristiche utili, come dispersione eccellente, capacità di flusso elevata, bassa densità, e proprietà di isolamento termico superiori 1, 2, 3, 4. A causa della loro struttura cava, HGM ha una bassissima conducibilità termica 10, 11. Per queste ragioni, sono applicati in molti settori, tra cui aerospaziale 5, esplorazione altura 6, 7, 8 stoccaggio di idrogeno, 9, ecc Tuttavia, ancora mostrano alcuni svantaggi, come la bassa resistenza. Inoltre, la luce IR è in grado di trasmettere attraverso HGM e riscaldare il soggetto dietro. Perciòe, modificazioni superficiali su HGM sono essenziali per ridurre il trasferimento termico radiativo. Un metodo efficace è quello di rivestire un materiale IR-bloccanti sulla superficie HGM. Come un semiconduttore, TiO 2 è stato utilizzato in molti settori, come fotocatalisi 12, 13, sviluppo celle solari, sensore fabbricazione 14, applicazioni ambientali 15, e accumulo di energia 16. Inoltre, mostra anche a bassa emissività nel visibile e dell&#39;infrarosso 17, 18, 19. Pertanto, per i nostri scopi, TiO 2 era una selezione prudente a causa del suo prezzo relativamente basso e alto rendimento. Tuttavia, il rivestimento è abbastanza facile per gli inquinanti al fallo, che colpisce seriamente la riflettività di TiO2. La riflettività deve ridurre gradualmente. Pertanto, un self-pulizia rivestimento è essenziale per evitare che il rivestimento da incrostazioni e per prolungare il tempo di lavoro di un tale rivestimento. In questo manoscritto, un metodo soft-chimica è stata utilizzata per sviluppare superhydrophobic TiO2 Rivestiti HGM. Tetrabutil titanato (OTC) e 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOTES) sono stati selezionati come sorgente Ti e agente superidrofobica, rispettivamente. Sono stati idrolizzati e depositate sulla superficie HGM. Poi, dopo il processo idrotermico, l&#39;anatasio TiO 2 formata sulla superficie HGM, e le proprietà superhydrophobic rimasto. Per confronto, PFOTES singolo rivestito HGM (F-SCHGM) e TiO 2 single-rivestito HGM (Ti-SCHGM) sono stati sintetizzati pure. Lo schema di sintesi è illustrato in Figura 1.

<table><tbody><tr><td>HGM</td><td>Technical Institute of Physics and Chemistry, Chinese Academy of Science</td><td>N/A</td><td>N/A</td></tr><tr><td>TBT</td><td>Sigma-Aldrich</td><td>CAS#: 5593-70-4</td><td>Analytical grade</td></tr><tr><td>Ethyl Alcohol</td><td>Sigma-Aldrich</td><td>CAS#: 64-17-5</td><td>Analytical grade</td></tr><tr><td>PFOTES</td><td>Sigma-Aldrich</td><td>CAS#: 51851-37-7</td><td>98%</td></tr></tbody></table>

tio2-coated hollow glass microspheres with superhydrophobic and high ir-reflective properties synthesized by a soft-chemistry method

Questo manoscritto propone un metodo soft-chimica per sviluppare microsfere cave di vetro superhydrophobic e altamente IR-riflettenti (HGM). L&#39;anatasio TiO 2 ed un agente superhydrophobic sono state rivestite in superficie HGM in un unico passaggio. TBT e PFOTES stati selezionati come sorgente di Ti e l&#39;agente superidrofobica, rispettivamente. Entrambi sono stati rivestiti sulla HGM, e dopo il processo idrotermico, il TBT rivolto a anatasio TiO 2. In questo modo, un PFOTES / TiO 2 Rivestiti HGM (MCHGM) fu preparato. Per confronto, PFOTES singolo rivestito HGM (F-SCHGM) e TiO 2 single-rivestito HGM (Ti-SCHGM) sono stati sintetizzati pure. I PFOTES e TiO 2 rivestimenti sulla superficie HGM state dimostrate mediante diffrazione di raggi X (XRD), microscopia elettronica a scansione (SEM), e caratterizzazioni rivelatore a dispersione di energia (EDS). Il MCHGM mostrato un maggiore angolo di contatto (153 °), ma un angolo inferiore scorrevole (16 °) rispetto F-SCHGM, con un angolo di contatto di 141,26; e un angolo di 67 ° scorrevole. Inoltre, sia Ti-SCHGM e MCHGM visualizzati valori IR riflettività simili, che erano superiori a circa il 5,8% rispetto all&#39;originale HGM e F-SCHGM. Inoltre, il rivestimento PFOTES appena cambiato la conducibilità termica. Pertanto, F-SCHGM, con una conducibilità termica di 0,0479 W / (m · K), era piuttosto come l&#39;originale HGM, che era 0,0475 W / (m · K). MCHGM e Ti-SCHGM erano anche simili. I loro valori di conducibilità termica erano 0,0543 W / (m · K) e 0,0543 W / (m · K), rispettivamente. Il rivestimento TiO 2 leggermente aumentato la conduttività termica, ma con l&#39;aumento della riflettività, la struttura complessiva isolamento termico è stata migliorata. Infine, poiché la proprietà IR-riflettente è fornita dal rivestimento HGM, se il rivestimento viene sporcata, la riflettività diminuisce. Pertanto, con il rivestimento superhydrophobic, la superficie è protetta da incrostazioni, e la sua durata è anche prolungato.

I test in fase 4.4 rivelano molte caratteristiche e proprietà dei campioni. La XRD (Figura 2) riflette la formazione di anatasio TiO 2. Il SEM (Figura 3) e EDS (Figura 4) visualizzare la TiO 2 e PFOTES che sono rivestite in superficie HGM. L&#39;angolo di contatto (figura 5) e l&#39;angolo di scorrimento (Figura 6) Test rappresentano la superhydrophobicity. Il test trasmittanza Vis...

Watch this Scientific Journal Video about TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method at JoVE.com

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

TiO<sub&gt; 2</sub&gt; Rivestiti microsfere cave di vetro con proprietà superidrofobiche e High IR-riflettenti sintetizzato da un metodo Soft-chimica

This manuscript proposes a soft-chemistry method to develop superhydrophobic and highly IR-reflective hollow glass microspheres (HGM). The anatase TiO2 ...

tio2-coated-hollow-glass-microspheres-with-superhydrophobic-high-ir

Research

JoVE Journal

Chemistry

TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

10.0K Views.  City University of Hong Kong. This manuscript proposes a soft-chemistry method to synthesize superhydrophobic, TiO2-coated hollow glass microspheres (HGM) with high IR-reflective properties.

Video: TiO2-coated Hollow Glass Microspheres with Superhydrophobic and High IR-reflective Properties Synthesized by a Soft-chemistry Method

Fabrication of Silica Ultra High Quality Factor Microresonators

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the quality factor (Q) of the cavity, can be in excess of 500ns for cavities with Q factors above 100 million. As a result of their low material losses, silica microcavities have demonstrated some of the longest photon lifetimes to date1-2. Since a portion of the circulating light extends outside the resonator, these devices can also be used to probe the surroundings. This interaction has enabled numerous experiments in biology, such as single molecule biodetection and antibody-antigen kinetics, as well as discoveries in other fields, such as development of ultra-low-threshold microlasers, characterization of thin films, and cavity quantum electrodynamics studies.3-7
The two primary silica resonant cavity geometries are the microsphere and the microtoroid. Both devices rely on a carbon dioxide laser reflow step to achieve their ultra-high-Q factors (Q&gt;100 million).1-2,8-9 However, there are several notable differences between the two structures. Silica microspheres are free-standing, supported by a single optical fiber, whereas silica microtoroids can be fabricated on a silicon wafer in large arrays using a combination of lithography and etching steps. These differences influence which device is optimal for a given experiment.
Here, we present detailed fabrication protocols for both types of resonant cavities. While the fabrication of microsphere resonant cavities is fairly straightforward, the fabrication of microtoroid resonant cavities requires additional specialized equipment and facilities (cleanroom). Therefore, this additional requirement may also influence which device is selected for a given experiment.
Introduction
An optical resonator efficiently confines light at specific wavelengths, known as the resonant wavelengths of the device. 1-2 The common figure of merit for these optical resonators is the quality factor or Q. This term describes the photon lifetime (&tau;o) within the resonator, which is directly related to the resonator's optical losses. Therefore, an optical resonator with a high Q factor has low optical losses, long photon lifetimes, and very low photon decay rates (1/&tau;o). As a result of the long photon lifetimes, it is possible to build-up extremely large circulating optical field intensities in these devices. This very unique property has allowed these devices to be used as laser sources and integrated biosensors.10
A unique sub-class of resonators is the whispering gallery mode optical microcavity. In these devices, the light is confined in circular orbits at the periphery. Therefore, the field is not completely confined within the device, but evanesces into the environment. Whispering gallery mode optical cavities have demonstrated some of the highest quality factors of any optical resonant cavity to date.9,11 Therefore, these devices are used throughout science and engineering, including in fundamental physics studies and in telecommunications as well as in biodetection experiments. 3-7,12
Optical microcavities can be fabricated from a wide range of materials and in a wide variety of geometries. A few examples include silica and silicon microtoroids, silicon, silicon nitride, and silica microdisks, micropillars, and silica and polymer microrings.13-17 The range in quality factor (Q) varies as dramatically as the geometry. Although both geometry and high Q are important considerations in any field, in many applications, there is far greater leverage in boosting device performance through Q enhancement. Among the numerous options detailed previously, the silica microsphere and the silica microtoroid resonator have achieved some of the highest Q factors to date.1,9 Additionally, as a result of the extremely low optical loss of silica from the visible through the near-IR, both microspheres and microtoroids are able to maintain their Q factors over a wide range of testing wavelengths.18 Finally, because silica is inherently biocompatible, it is routinely used in biodetection experiments.
In addition to high material absorption, there are several other potential loss mechanisms, including surface roughness, radiation loss, and contamination loss.2 Through an optimization of the device size, it is possible to eliminate radiation losses, which arise from poor optical field confinement within the device. Similarly, by storing a device in an appropriately clean environment, contamination of the surface can be minimized. Therefore, in addition to material loss, surface scattering is the primary loss mechanism of concern.2,8
In silica devices, surface scattering is minimized by using a laser reflow technique, which melts the silica through surface tension induced reflow. While spherical optical resonators have been studied for many years, it is only with recent advances in fabrication technologies that researchers been able to fabricate high quality silica optical toroidal microresonators (Q&gt;100 million) on a silicon substrate, thus paving the way for integration with microfluidics.1
The present series of protocols details how to fabricate both silica microsphere and microtoroid resonant cavities. While silica microsphere resonant cavities are well-established, microtoroid resonant cavities were only recently invented.1 As many of the fundamental methods used to fabricate the microsphere are also used in the more complex microtoroid fabrication procedure, by including both in a single protocol it will enable researchers to more easily trouble-shoot their experiments.

We describe the use of a carbon dioxide laser reflow technique to fabricate silica resonant cavities, including free-standing microspheres and on-chip microtoroids. The reflow method removes surface imperfections, allowing long photon lifetimes within both devices. The resulting devices have ultra high quality factors, enabling applications ranging from telecommunications to biodetection.

Fabbricazione di Microrisonatori silice Ultra High Quality Factor

Whispering gallery resonant cavities confine light in circular orbits at their periphery.1-2 The photon storage lifetime in the cavity, quantified by the ...

Ricerca

Ingegneria

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials.
Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4.
To promote a photovoltaic charge separation, we use a composite two-layer solid of PbS and TiO2 films. In this configuration, photoinduced electrons are injected into TiO2 and are subsequently picked up by an FTO electrode, while holes are channeled to a Au electrode via PbS layer6. To develop the latter we introduce a Semiconductor Matrix Encapsulated Nanocrystal Arrays (SMENA) strategy, which allows bonding PbS NCs into the surrounding matrix of CdS semiconductor. As a result, fabricated solids exhibit excellent thermal stability, attributed to the heteroepitaxial structure of nanocrystal-matrix interfaces, and show compelling light-harvesting performance in prototype solar cells7.

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

Raccolta di energia solare per mezzo di separatori di carica-nanocristalli e loro Solidi

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials ...

Attaching Biological Probes to Silica Optical Biosensors Using Silane Coupling Agents

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) technique), make use of various surface modification techniques, that can, for example, prevent surface fouling, tune the hydrophobicity / hydrophilicity of the surface, adapt to a variety of electronic environments, and most frequently, induce specificity towards a target of interest.1-5 These techniques extend the functionality of otherwise highly sensitive biosensors to real-world applications in complex environments, such as blood, urine, and wastewater analysis.2,6-7 While commercial biosensing platforms, such as Biacore, have well-understood, standard techniques for performing such surface modifications, these techniques have not been translated in a standardized fashion to other label-free biosensing platforms, such as Whispering Gallery Mode (WGM) optical resonators.8-9
WGM optical resonators represent a promising technology for performing label-free detection of a wide variety of species at ultra-low concentrations.6,10-12 The high sensitivity of these platforms is a result of their unique geometric optics: WGM optical resonators confine circulating light at specific, integral resonance frequencies.13 Like the SPR platforms, the optical field is not totally confined to the sensor device, but evanesces; this "evanescent tail" can then interact with species in the surrounding environment. This interaction causes the effective refractive index of the optical field to change, resulting in a slight, but detectable, shift in the resonance frequency of the device. Because the optical field circulates, it can interact many times with the environment, resulting in an inherent amplification of the signal, and very high sensitivities to minor changes in the environment.2,14-15
To perform targeted detection in complex environments, these platforms must be paired with a probe molecule (usually one half of a binding pair, e.g. antibodies / antigens) through surface modification.2 Although WGM optical resonators can be fabricated in several geometries from a variety of material systems, the silica microsphere is the most common. These microspheres are generally fabricated on the end of an optical fiber, which provides a "stem" by which the microspheres can be handled during functionalization and detection experiments. Silica surface chemistries may be applied to attach probe molecules to their surfaces; however, traditional techniques generated for planar substrates are often not adequate for these three-dimensional structures, as any changes to the surface of the microspheres (dust, contamination, surface defects, and uneven coatings) can have severe, negative consequences on their detection capabilities. Here, we demonstrate a facile approach for the surface functionalization of silica microsphere WGM optical resonators using silane coupling agents to bridge the inorganic surface and the biological environment, by attaching biotin to the silica surface.8,16 Although we use silica microsphere WGM resonators as the sensor system in this report, the protocols are general and can be used to functionalize the surface of any silica device with biotin.

Biosensors interface with complex, biological environments and perform targeted detection by combining highly sensitive sensors with highly specific probes attached to the sensor via surface modification. Here, we demonstrate the surface functionalization of silica optical sensors with biotin using silane coupling agents to bridge the sensor and the biological environment.

Collegamento sonde biologiche ai biosensori ottici che utilizza silice agenti di accoppiamento silanici

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) ...

Bioingegneria

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

Sintesi e caratterizzazione di supramolecolari colloidi

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Chimica

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

Fabbricazione di microsfere di polimeri per risonatore ottico e applicazioni laser

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Synthesizing Sodium Tungstate and Sodium Molybdate Microcapsules via Bacterial Mineral Excretion

We present a method, the bacterial mineral excretion (BME), for synthesizing two kinds of microcapsules, sodium tungstate and sodium molybdate, and the two metal oxides&#39; corresponding nanoparticles&#8212;the former being as small as 22 nm and the latter 15 nm. We fed two strains of bacteria, Shewanella algae and Pandoraea sp., with various concentrations of tungstate or molybdate ions. The concentrations of tungstate and molybdate were adjusted to make microcapsules of different length-to-diameter ratios. We found that the higher the concentration the smaller the nanoparticles were. The nanoparticles came in with three length-to-diameter ratios: 10:1, 3:1 and 1:1, which were achieved by feeding the bacteria respectively with a low concentration, a medium concentration, and a high concentration. The images of the hollow microcapsules were taken via the scanning electron microsphere (SEM). Their crystal structures were verified by X-ray diffraction (XRD)&#8212;the crystal structure of molybdate microcapsules is Na2MoO4 and that of tungstate microcapsules is Na2WO4 with Na2W2O7. These syntheses all were accomplished under a near ambient condition.

This work presents a protocol for manufacture sodium tungstate and sodium molybdate microcapsules via bacteria and their corresponding nanoparticles.

Sintetizzando il tungstato di sodio e sodio molibdato microcapsule tramite escrezione minerale batterica

We present a method, the bacterial mineral excretion (BME), for synthesizing two kinds of microcapsules, sodium tungstate and sodium molybdate, and the ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in industry. The wettability of the produced surface was analyzed by bouncing drop experiments and the topography was analyzed by confocal microscopy. In addition, we show various methodologies to measure its durability and anti-icing properties. Superhydrophobic surfaces hold a special texture that must be preserved to keep their water-repellency. To fabricate durable surfaces, we followed two strategies to incorporate a resistant texture. The first strategy is a direct incorporation of roughness to the metal substrate by acid etching. After this surface texturization, the surface energy was decreased by silanization or fluoropolymer deposition. The second strategy is the growth of a ceria layer (after surface texturization) that should enhance the surface hardness and corrosion resistance. The surface energy was decreased with a stearic acid film.
The durability of the superhydrophobic surfaces was examined by a particle impact test, mechanical wear by lateral abrasion, and UV-ozone resistance. The anti-icing properties were explored by studying the ability to repeal subcooled water, freezing delay, and ice adhesion.

We illustrate several methodologies to produce superhydrophobic metal surfaces and to explore their durability and anti-icing properties.

Fabbricazione di superfici superidrofobiche metalliche per applicazioni Anti-Icing

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe a novel protocol employing the TiO2 photocatalysis to locally alter cell affinity of the substrate surface. For this experiment, a thin TiO2 film was sputter-coated on a glass coverslip, and the TiO2 surface was subsequently modified with an organosilane monolayer derived from octadecyltrichlorosilane (OTS), which inhibits cell adhesion. The sample was immersed in a cell culture medium, and focused UV light was irradiated to an octagonal region. When a neuronal cell line PC12 cells were plated on the sample, cells adhered only on the UV-irradiated area. We further show that this surface modification can also be performed in situ, i.e., even when cells are growing on the substrate. Proper modification of the surface required an extracellular matrix protein collagen to be present in the medium at the time of UV irradiation. The technique presented here can potentially be employed in patterning multiple cell types for constructing coculture systems or to arbitrarily manipulate cells under culture.

Photopatterning Proteins and Cells in Aqueous Environment Using TiO2 Photocatalysis

We describe a protocol for modifying cell affinity of a scaffold surface in aqueous environment. The method takes advantage of titanium dioxide photocatalysis to decompose organic film in the photo-irradiated region. We show that it can be used to create microdomains of scaffolding proteins, both ex situ and in situ.

Photopatterning proteine ​​e cellule in acquosa ambiente utilizzando TiO<sub&gt; 2</sub&gt; Fotocatalisi

Organic contaminants adsorbed on the surface of titanium dioxide (TiO2) can be decomposed by photocatalysis under ultraviolet (UV) light. Here we describe ...

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

Un Facile metodo sintetico per ottenere bismuto Oxyiodide microsfere altamente funzionale per i processi fotocatalitici di depurazione delle acque

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

We present microfabrication protocols for rendering intrinsically wetting materials repellent to liquids (omniphobic) by creating gas-entrapping microtextures (GEMs) on them comprising cavities and pillars with reentrant and doubly reentrant features. Specifically, we use SiO2/Si as the model system and share protocols for two-dimensional (2D) designing, photolithography, isotropic/anisotropic etching techniques, thermal oxide growth, piranha cleaning, and storage towards achieving those microtextures. Even though the conventional wisdom indicates that roughening intrinsically wetting surfaces (&#952;o &#60; 90&#176;) renders them even more wetting (&#952;r &#60; &#952;o &#60; 90&#176;), GEMs demonstrate liquid repellence despite the intrinsic wettability of the substrate. For instance, despite the intrinsic wettability of silica &#952;o &#8776; 40&#176; for the water/air system, and &#952;o &#8776; 20&#176; for the hexadecane/air system, GEMs comprising cavities entrap air robustly on immersion in those liquids, and the apparent contact angles for the droplets are &#952;r &#62; 90&#176;. The reentrant and doubly reentrant features in the GEMs stabilize the intruding liquid meniscus thereby trapping the liquid-solid-vapor system in metastable air-filled states (Cassie states) and delaying wetting transitions to the thermodynamically-stable fully-filled state (Wenzel state) by, for instance, hours to months. Similarly, SiO2/Si surfaces with arrays of reentrant and doubly reentrant micropillars demonstrate extremely high contact angles (&#952;r &#8776; 150&#176;&#8211;160&#176;) and low contact angle hysteresis for the probe liquids, thus characterized as superomniphobic. However, on immersion in the same liquids, those surfaces dramatically lose their superomniphobicity and get fully-filled within &#60;1 s. To address this challenge, we present protocols for hybrid designs that comprise arrays of doubly reentrant pillars surrounded by walls with doubly reentrant profiles. Indeed, hybrid microtextures entrap air on immersion in the probe liquids. To summarize, the protocols described here should enable the investigation of GEMs in the context of achieving omniphobicity without chemical coatings, such as perfluorocarbons, which might unlock the scope of inexpensive common materials for applications as omniphobic materials. Silica microtextures could also serve as templates for soft materials.

Rendering SiO2/Si Surfaces Omniphobic by Carving Gas-Entrapping Microtextures Comprising Reentrant and Doubly Reentrant Cavities or Pillars

This work presents microfabrication protocols for achieving cavities and pillars with reentrant and doubly reentrant profiles on SiO2/Si wafers using photolithography and dry etching. Resulting microtextured surfaces demonstrate remarkable liquid repellence, characterized by robust long-term entrapment of air under wetting liquids, despite the intrinsic wettability of silica.

Rendering di siO2/Si Superfici omnifobiche da intaglio Gas-Entrapping Microtextures Comprising Reentrant e Doubly Reentrant Cavities or Pillars

TiO

Riepilogo

Esplora Altri Video

Capitoli in questo video

Fabbricazione di Microrisonatori silice Ultra High Quality Factor

Raccolta di energia solare per mezzo di separatori di carica-nanocristalli e loro Solidi

Collegamento sonde biologiche ai biosensori ottici che utilizza silice agenti di accoppiamento silanici

Sintesi e caratterizzazione di supramolecolari colloidi

Fabbricazione di microsfere di polimeri per risonatore ottico e applicazioni laser

Sintetizzando il tungstato di sodio e sodio molibdato microcapsule tramite escrezione minerale batterica

Fabbricazione di superfici superidrofobiche metalliche per applicazioni Anti-Icing

Photopatterning proteine e cellule in acquosa ambiente utilizzando TiO

Un Facile metodo sintetico per ottenere bismuto Oxyiodide microsfere altamente funzionale per i processi fotocatalitici di depurazione delle acque

Rendering di siO₂/Si Superfici omnifobiche da intaglio Gas-Entrapping Microtextures Comprising Reentrant e Doubly Reentrant Cavities or Pillars

TiO

Riepilogo

Esplora Altri Video

Capitoli in questo video

Fabbricazione di Microrisonatori silice Ultra High Quality Factor

Raccolta di energia solare per mezzo di separatori di carica-nanocristalli e loro Solidi

Collegamento sonde biologiche ai biosensori ottici che utilizza silice agenti di accoppiamento silanici

Sintesi e caratterizzazione di supramolecolari colloidi

Fabbricazione di microsfere di polimeri per risonatore ottico e applicazioni laser

Sintetizzando il tungstato di sodio e sodio molibdato microcapsule tramite escrezione minerale batterica

Fabbricazione di superfici superidrofobiche metalliche per applicazioni Anti-Icing

Photopatterning proteine ​​e cellule in acquosa ambiente utilizzando TiO

Un Facile metodo sintetico per ottenere bismuto Oxyiodide microsfere altamente funzionale per i processi fotocatalitici di depurazione delle acque

Rendering di siO2/Si Superfici omnifobiche da intaglio Gas-Entrapping Microtextures Comprising Reentrant e Doubly Reentrant Cavities or Pillars

Photopatterning proteine e cellule in acquosa ambiente utilizzando TiO

Rendering di siO₂/Si Superfici omnifobiche da intaglio Gas-Entrapping Microtextures Comprising Reentrant e Doubly Reentrant Cavities or Pillars