Diffusion of single dye molecules in hydrated TiO<sub>2</sub> mesoporous films

Angiolini, Juan Francisco; Stortz, Martín; Steinberg, Paula Y.; Mocskos, Esteban; Bruno, Luciana; Soler-Illia, Galo J. A. A.; Angelomé, Paula C.; Wolosiuk, Alejandro; Levi, Valeria

doi:10.1039/c7cp05186g

Cited by 17 publications

(22 citation statements)

References 48 publications

(39 reference statements)

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“…Moreover, these results indicate that, for all tested cases, the TF film is fully accessible for molecule diffusion from the external solution to the metal NP surface. nm, a pore diameter around 8 nm according to ellipsometric porosimetry 48 , and a porosity of 45 %, as determined by XRR. The formation of the NPs inside the mesoporous TiO 2 thin film was achieved by repeating the adsorption-reduction process as described above.…”

Section: Resultsmentioning

confidence: 99%

Au Nanoparticles–Mesoporous TiO₂ Thin Films Composites as SERS Sensors: A Systematic Performance Analysis

et al. 2018

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The combination of plasmonic nanoparticles and mesoporous materials is of much interest in applications such as sensing or catalysis. The production of such hybrid materials can be done in various ways, leading to different architectures. We present a comparative study of the SERS performance of different nanocomposite architectures comprising mesoporous TiO 2 thin films and Au nanoparticles (NPs). The selection of TiO 2 as mesoporous support material was based on its high chemical and mechanical stability. Au NPs of different sizes and shapes were placed at different locations of the composite and used as a plasmonic material compatible with the synthesis conditions of the mesoporous films, displaying a high chemical stability. Using pnitrothiophenol as a molecular probe, we evaluated the performance toward surface-enhanced Raman scattering (SERS) sensing, on the basis of minimum acquisition time, spot-to-spot reproducibility and limit of detection. The obtained results indicate that each platform features different sensing capabilities. While systems comprising Au NPs within the mesopores allow working with low acquisition times and present high signal uniformity, only a detection limit of μM was achieved. On the other hand, those systems made of branched Au NPs covered with mesoporous films require low acquisition times and can achieve detection limits as low as 10 pM, but signal uniformity is compromised. We propose that careful comparison of different SERS platforms based on Au NPs and mesoporous thin films will facilitate selecting an appropriate configuration for any desired application.

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Section: Resultsmentioning

confidence: 99%

Au Nanoparticles–Mesoporous TiO₂ Thin Films Composites as SERS Sensors: A Systematic Performance Analysis

et al. 2018

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“…The fluorescence intensities of each bleached region and a reference, unbleached region of the nucleus were determined for every time point and normalized to the average intensity of the same region before the photobleaching. Then, the ratio between the normalized intensity of the bleached and reference regions was calculated [106] and fitted with an empirical simple exponential equation (Eq. 2) to obtain a characteristic recovery time (τ c ):…”

Section: Fluorescence Recovery After Photobleachingmentioning

confidence: 99%

Unraveling the molecular interactions involved in phase separation of glucocorticoid receptor

et al. 2020

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Background: Functional compartmentalization has emerged as an important factor modulating the kinetics and specificity of biochemical reactions in the nucleus, including those involved in transcriptional regulation. The glucocorticoid receptor (GR) is a ligand-activated transcription factor that translocates to the nucleus upon hormone stimulation and distributes between the nucleoplasm and membraneless compartments named nuclear foci. While a liquid-liquid phase separation process has been recently proposed to drive the formation of many nuclear compartments, the mechanisms governing the heterogeneous organization of GR in the nucleus and the functional relevance of foci formation remain elusive. Results: We dissected some of the molecular interactions involved in the formation of GR condensates and analyzed the GR structural determinants relevant to this process. We show that GR foci present properties consistent with those expected for biomolecular condensates formed by a liquid-liquid phase separation process in living human cells. Their formation requires an initial interaction of GR with certain chromatin regions at specific locations within the nucleus. Surprisingly, the intrinsically disordered region of GR is not essential for condensate formation, in contrast to many nuclear proteins that require disordered regions to phase separate, while the ligandbinding domain seems essential for that process. We finally show that GR condensates include Mediator, a protein complex involved in transcription regulation. Conclusions: We show that GR foci have properties of liquid condensates and propose that active GR molecules interact with chromatin and recruit multivalent cofactors whose interactions with additional molecules lead to the formation of a focus. The biological relevance of the interactions occurring in GR condensates supports their involvement in transcription regulation.

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“…72 During desorption, the relative pressure at which the liquid water evaporates from the porous network ( Figure 3a) provides information on the size of necks connecting the pores (Figure 3b), thus offering critically important information on the changing the nature of the SDA, 75 but here we demonstrate that it is possible to swell both the pore volume and pore interconnections using a swelling agent. It has been shown that the size of pore interconnections can have a direct impact on the liquid and vapour infiltration within the porous network 76,77 In more general terms, mass transport of molecules through porous films is strongly dependent on open pores which are highly interconnected allowing for efficient diffusion of molecules through the network. 78 Such applications include electrochemistry, 79 nanoparticle synthesis, 75 sensing, 75,77 controlled release 80 and photocatalysis.…”

Section: Both Samples Exhibited Hysteresis Loops Between the Adsorptimentioning

confidence: 99%

Tuning Pore Dimensions of Mesoporous Inorganic Films by Homopolymer Swelling

Reid¹,

Fernandez²,

Schmidt‐Hansberg³

et al. 2019

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The functionality and applications of mesoporous inorganic films are closely linked to their mesopore dimensions. For material architectures derived from block copolymer (BCP) micelle co-assembly, the pore size is typically manipulated by changing the molecular weight corresponding to the pore-forming block. However, bespoke BCP synthesis is often a costly and time-consuming process. An alternative method for pore size tuning involves the use of swelling agents, such as homopolymers (HPs), which selectively interact with the core-forming block to increase the micelle size in solution. In this work, poly(isobutylene)-block-poly(ethylene oxide) (PIB-b-PEO) micelles were swollen with poly(isobutylene) HP in solution and co-assembled with aluminosilicate sol with the aim of increasing the resulting pore dimensions. An analytical approach implementing spectroscopic ellipsometry (SE) and ellipsometric porosimetry (EP) alongside the more commonly used atomic force microscopy (AFM) and small angle x-ray scattering in transmission (SAXS) and grazing-incidence (GISAXS) modes enabled to study the material evolution from solution processing through to the manifestation of the mesoporous inorganic film after BCP removal. In-depth SE/EP analysis evidenced an increase of over 40% in mesopore diameter with HP swelling and a consistent scaling of the overall void volume and number of pores. Importantly, our analytical tool-box enabled us to study the effect of swelling on the connecting necks between adjacent pores, with observed increases as high as ≈35%, knowledge of which is crucial to sensing, electrochemical and other mass transfer-dependent applications.

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Diffusion of single dye molecules in hydrated TiO₂ mesoporous films

Cited by 17 publications

References 48 publications

Au Nanoparticles–Mesoporous TiO₂ Thin Films Composites as SERS Sensors: A Systematic Performance Analysis

Au Nanoparticles–Mesoporous TiO₂ Thin Films Composites as SERS Sensors: A Systematic Performance Analysis

Unraveling the molecular interactions involved in phase separation of glucocorticoid receptor

Tuning Pore Dimensions of Mesoporous Inorganic Films by Homopolymer Swelling

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Diffusion of single dye molecules in hydrated TiO2 mesoporous films

Cited by 17 publications

References 48 publications

Au Nanoparticles–Mesoporous TiO2 Thin Films Composites as SERS Sensors: A Systematic Performance Analysis

Au Nanoparticles–Mesoporous TiO2 Thin Films Composites as SERS Sensors: A Systematic Performance Analysis

Unraveling the molecular interactions involved in phase separation of glucocorticoid receptor

Tuning Pore Dimensions of Mesoporous Inorganic Films by Homopolymer Swelling

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Product

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Diffusion of single dye molecules in hydrated TiO₂ mesoporous films

Au Nanoparticles–Mesoporous TiO₂ Thin Films Composites as SERS Sensors: A Systematic Performance Analysis

Au Nanoparticles–Mesoporous TiO₂ Thin Films Composites as SERS Sensors: A Systematic Performance Analysis