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Eygeris Y, White EV, Wang Q, Carpenter JE, Grünwald M, Zharov I. Responsive Nanoporous Membranes with Size Selectivity and Charge Rejection from Self-Assembly of Polyelectrolyte "Hairy" Nanoparticles. ACS APPLIED MATERIALS & INTERFACES 2019; 11:3407-3416. [PMID: 30589251 DOI: 10.1021/acsami.8b17483] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report the preparation and characterization of charged nanoporous membranes by self-assembly of "hairy" silica nanoparticles (HNPs) functionalized with polyelectrolyte copolymer brushes. We show that HNP membranes possess high water flux, have well-defined pore sizes, and rejection up to 80% of charged species in solution. The properties of these membranes can be tuned by controlling the length and composition of polymer brushes and the electrolyte concentration in solution. We demonstrate that membrane pore sizes undergo changes of up to 40% in response to changes in the ionic strength of the salt solution. Using MD computer simulations of a coarse-grained model, we link these tunable properties to the conformations of polymer chains in the spaces between randomly packed HNPs. As polymer length increases, the polymers fill the interparticle gaps, and the pore size decreases markedly. On the basis of their straightforward fabrication and tunable properties, HNP membranes may find applications in size- and charge-selective separations, water desalination, and responsive devices.
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Affiliation(s)
| | | | | | | | | | - Ilya Zharov
- A. M. Butlerov Chemistry Institute , Kazan Federal University , 18 Kremlyovskaya Street , Kazan 420008 , Russia
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Yao L, Filice FP, Yang Q, Ding Z, Su B. Quantitative Assessment of Molecular Transport through Sub-3 nm Silica Nanochannels by Scanning Electrochemical Microscopy. Anal Chem 2018; 91:1548-1556. [DOI: 10.1021/acs.analchem.8b04795] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Lina Yao
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University, Hangzhou 310012, China
- Department of Chemistry, Western University, London N6A 5B7, Canada
| | - Fraser P. Filice
- Department of Chemistry, Western University, London N6A 5B7, Canada
| | - Qian Yang
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University, Hangzhou 310012, China
| | - Zhifeng Ding
- Department of Chemistry, Western University, London N6A 5B7, Canada
| | - Bin Su
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University, Hangzhou 310012, China
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Ignacio-de Leon PAA, Eygeris Y, Haynes R, Zharov I. Diffusion of Proteins across Silica Colloidal Crystals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10333-10339. [PMID: 30086633 DOI: 10.1021/acs.langmuir.8b01261] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We studied the diffusion of three model proteins, lysozyme (Lz), bovine hemoglobin (BHb), and bovine serum albumin (BSA), normal to the (111) plane of sintered silica colloidal crystals with three different pore "radii" (7.5, 19, and 27 nm). We demonstrated that these colloidal crystals exhibit size selectivity when the nanopores are sufficiently small (7.5 and 19 nm). Because these nanopores are still larger than the diffusing proteins, the observed size selectivity can be attributed to the tortuosity of the colloidal nanopores. Larger (27 nm) nanopores led to higher transport rates but at the cost of selectivity. In addition to the size selectivity, we also demonstrated that 19 nm nanopores possess shape selectivity for the proteins of comparable molecular weights. We showed that the high temperature sintering required for the preparation of sintered colloidal crystals reduces the extent of interactions between the proteins and the nanopore surface, which appear to play a minor role in the diffusion, and that transport selectivity is decided solely by protein size and shape. Taken together, our observations suggest that sintered silica colloidal crystals constitute promising nanoporous membranes for protein separations, with easily controllable pore size, size and shape selectivity, and minimal surface fouling.
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Affiliation(s)
| | - Yulia Eygeris
- Department of Chemistry , University of Utah , 315 S 1400 E , Salt Lake City , Utah 84112 , United States
| | - Robert Haynes
- Department of Chemistry , University of Utah , 315 S 1400 E , Salt Lake City , Utah 84112 , United States
| | - Ilya Zharov
- Department of Chemistry , University of Utah , 315 S 1400 E , Salt Lake City , Utah 84112 , United States
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Ouyang W, Han J, Wang W. Nanofluidic crystals: nanofluidics in a close-packed nanoparticle array. LAB ON A CHIP 2017; 17:3006-3025. [PMID: 28752878 PMCID: PMC5602602 DOI: 10.1039/c7lc00588a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
With various promising applications demonstrated, nanofluidics has been of broad research interest in the past decade. As nanofluidics matures from a proof of concept towards practical applications, it faces two major barriers: expensive nanofabrication and ultra-low throughput. To date, the only material that enables nanofabrication-free, high-throughput, yet precisely controllable nanofluidic systems is the close-packed nanoparticle array, i.e. nanofluidic crystals. Recently, significant progress in nanofluidics has been made using nanofluidic crystals, including high-current ionic diodes, high-power energy harvesters, efficient biomolecular separation, and facile biosensors. Nanofluidic crystals are seen as a key to applying nanofluidic concepts to real-world applications. In this review, we introduce the key concepts and models in nanofluidic crystals, summarize the fabrication methods, and discuss the various applications of nanofluidic crystals in depth, highlighting their advantages in terms of simple fabrication, low cost, flexibility, and high throughput. Finally, we provide our perspectives on the future of nanofluidic crystals and their potential impacts.
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Affiliation(s)
- Wei Ouyang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, United States
- Institute of Microelectronics, Peking University, Beijing, 100871, P.R. China
| | - Jongyoon Han
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, United States
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, United States
| | - Wei Wang
- Institute of Microelectronics, Peking University, Beijing, 100871, P.R. China
- National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Beijing, 100871, P.R. China
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Wang C, Yang H, Tian L, Wang S, Gao N, Zhang W, Wang P, Yin X, Li G. Facile fabrication of highly controllable gating systems based on the combination of inverse opal structure and dynamic covalent chemistry. NANOSCALE 2017; 9:7268-7275. [PMID: 28524916 DOI: 10.1039/c7nr00881c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A three-dimensional (3D) inverse opal with periodic and porous structures has shown great potential for applications not only in optics and optoelectronics, but also in functional membranes. In this work, the benzaldehyde group was initially introduced into a 3D nanoporous inverse opal, serving as a platform for fabricating functional membranes. By employing the dynamic covalent approach, a highly controllable gating system was facilely fabricated to achieve modulable and reversible transport features. It was found that the physical/chemical properties and pore size of the gating system could easily be regulated through post-modification with amines. As a demonstration, the gated nanopores were modified with three kinds of amines to control the wettability, surface charge and nanopore size which in turn was exploited to achieve selective mass transport, including hydrophobic molecules, cations and anions, and the transport with respect to the physical steric hindrance. In particular, the gating system showed extraordinary reversibility and could recover to its pristine state by simply changing pH values. Due to the unlimited variety provided by the Schiff base reaction, the inverse opal described here exhibits a significant extendibility and could be easily post-modified with stimuli-responsive molecules for special purposes. Furthermore, this work can be extended to employ other dynamic covalent routes, for example Diels-Alder, ester exchange and disulfide exchange-based routes.
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Affiliation(s)
- Chen Wang
- Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
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Lin X, Yang Q, Yan F, Zhang B, Su B. Gated Molecular Transport in Highly Ordered Heterogeneous Nanochannel Array Electrode. ACS APPLIED MATERIALS & INTERFACES 2016; 8:33343-33349. [PMID: 27934137 DOI: 10.1021/acsami.6b13772] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In biology, all protein channels share a common feature of containing narrow pore regions with hydrophobic functional groups and selectivity filter regions abundant with charged residues, which work together to account for fast and selective mass transport in and out of cells. In this work, an ultrathin layer of polydimethylsiloxane (PDMS) was evaporated on the top orifices of charged silica nanochannels (2-3 nm in diameter and 60 nm in length) vertically attached to the electrode surface, and the resulting structure is designated as heterogeneous silica nanochannels (HSNs). As evidenced by voltammetric studies, the transport of ionic species in these HSNs was controlled by both hydrophobic rejection and electrostatic force arising from the top PDMS layer and from the bottom silica nanochannels, respectively. Anionic species encountered both hydrophobic rejection and electrostatic repulsion forces, and thus, their transport was strongly prohibited, while the transport of cationic species was permitted once the electrostatic attraction exceeded the hydrophobic rejection. Moreover, the magnitude of hydrophobic force could be regulated by the PDMS layer thickness, and that of the electrostatic force can be modulated by the salt concentration, solution pH, or applied voltage. It was demonstrated that the HSNs could be activated from an OFF state (no ion can transport) to an ON state (only cation transport occurs) by decreasing the salt concentration, increasing the solution pH, or applying negative voltages.
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Affiliation(s)
- Xingyu Lin
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University , Hangzhou 310058, P.R. China
| | - Qian Yang
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University , Hangzhou 310058, P.R. China
| | - Fei Yan
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University , Hangzhou 310058, P.R. China
| | - Bowen Zhang
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University , Hangzhou 310058, P.R. China
| | - Bin Su
- Institute of Analytical Chemistry, Department of Chemistry, Zhejiang University , Hangzhou 310058, P.R. China
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Ma C, Xu W, Wichert WRA, Bohn PW. Ion Accumulation and Migration Effects on Redox Cycling in Nanopore Electrode Arrays at Low Ionic Strength. ACS NANO 2016; 10:3658-64. [PMID: 26910572 DOI: 10.1021/acsnano.6b00049] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Ion permselectivity can lead to accumulation in zero-dimensional nanopores, producing a significant increase in ion concentration, an effect which may be combined with unscreened ion migration to improve sensitivity in electrochemical measurements, as demonstrated by the enormous current amplification (∼2000-fold) previously observed in nanopore electrode arrays (NEA) in the absence of supporting electrolyte. Ionic strength is a key experimental factor that governs the magnitude of the additional current amplification (AFad) beyond simple redox cycling through both ion accumulation and ion migration effects. Separate contributions from ion accumulation and ion migration to the overall AFad were identified by studying NEAs with varying geometries, with larger AFad values being achieved in NEAs with smaller pores. In addition, larger AFad values were observed for Ru(NH3)6(3/2+) than for ferrocenium/ferrocene (Fc(+)/Fc) in aqueous solution, indicating that coupling efficiency in redox cycling can significantly affect AFad. While charged species are required to observe migration effects or ion accumulation, poising the top electrode at an oxidizing potential converts neutral species to cations, which can then exhibit current amplification similar to starting with the cation. The electrical double layer effect was also demonstrated for Fc/Fc(+) in acetonitrile and 1,2-dichloroethane, producing AFad up to 100× at low ionic strength. The pronounced AFad effects demonstrate the advantage of coupling redox cycling with ion accumulation and migration effects for ultrasensitive electrochemical measurements.
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Affiliation(s)
- Chaoxiong Ma
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Wei Xu
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - William R A Wichert
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Paul W Bohn
- Department of Chemistry and Biochemistry and ‡Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
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Zharov I, Khabibullin A. Surface-modified silica colloidal crystals: nanoporous films and membranes with controlled ionic and molecular transport. Acc Chem Res 2014; 47:440-9. [PMID: 24397245 DOI: 10.1021/ar400157w] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Nanoporous membranes are important for the study of the transport of small molecules and macromolecules through confined spaces and in applications ranging from separation of biomacromolecules and pharmaceuticals to sensing and controlled release of drugs. For many of these applications, chemists need to gate the ionic and molecular flux through the nanopores, which in turn depends on the ability to control the nanopore geometry and surface chemistry. Most commonly used nanoporous membrane materials are based on polymers. However, the nanostructure of polymeric membranes is not well-defined, and their surface is hard to modify. Inorganic nanoporous materials are attractive alternatives for polymers in the preparation of nanoporous membranes. In this Account, we describe the preparation and surface modification of inorganic nanoporous films and membranes self-assembled from silica colloidal spheres. These spheres form colloidal crystals with close-packed face centered cubic lattices upon vertical deposition from colloidal solutions. Silica colloidal crystals contain ordered arrays of interconnected three dimensional voids, which function as nanopores. We can prepare silica colloidal crystals as supported thin films on various flat solid surfaces or obtain free-standing silica colloidal membranes by sintering the colloidal crystals above 1000 °C. Unmodified silica colloidal membranes are capable of size-selective separation of macromolecules, and we can surface-modify them in a well-defined and controlled manner with small molecules and polymers. For the surface modification with small molecules, we use silanol chemistry. We grow polymer brushes with narrow molecular weight distribution and controlled length on the colloidal nanopore surface using atom transfer radical polymerization or ring-opening polymerization. We can control the flux in the resulting surface-modified nanoporous films and membranes by pH and ionic strength, temperature, light, and small molecule binding. When we modify the surface of the colloidal nanopores with ionizable moieties, they can generate an electric field inside the nanopores, which repels ions of the same charge and attracts ions of the opposite charge. This allows us to electrostatically gate the ionic flux through colloidal nanopores, controlled by pH and ionic strength of the solution when surface amines or sulfonic acids are present or by irradiation with light in the case of surface spiropyran moieties. When we modify the surface of the colloidal nanopores with chiral moieties capable of stereoselective binding of enantiomers, we generate colloidal films with chiral permselectivity. By filling the colloidal nanopores with polymer brushes attached to the pore surface, we can control the ionic flux through the corresponding films and membranes electrostatically using reversibly ionizable polymer brushes. By filling the colloidal nanopores with polymer brushes whose conformation reversibly changes in response to pH, ionic strength, temperature, or small molecule binding, we can control the molecular flux sterically. There are various potential applications for surface-modified silica colloidal films and membranes. Due to their ordered nanoporous structure and mechanical durability, they are beneficial in nanofluidics, nanofiltration, separations, and fuel cells and as catalyst supports. Reversible gating of flux by external stimuli may be useful in drug release, in size-, charge-, and structure-selective separations, and in microfluidic and sensing devices.
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Affiliation(s)
- Ilya Zharov
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Amir Khabibullin
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
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Rutkowska IA, Koster MD, Blanchard GJ, Kulesza PJ. Nanoporous Platinum Electrodes as Substrates for Metal Oxide-Supported Noble Metal Electrocatalytic Nanoparticles: Synergistic Effects During Electrooxidation of Ethanol. Aust J Chem 2014. [DOI: 10.1071/ch14264] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Electrocatalytic oxidation of ethanol in acid medium (0.5 mol dm–3 H2SO4) was significantly enhanced by not only supporting bimetallic PtRu nanoparticles on nanostructured metal oxides (TiO2 or WO3), but also by depositing such catalytic systems on planar nanoporous platinized electrode substrates. Incorporation of TiO2 or WO3 into the electrocatalytic interface was likely to improve proton mobility and to provide –OH groups capable of inducing the removal of poisoning species, such as CO, from the Pt sites in the bimetallic PtRu catalyst. Synergistic interactions between ruthenium and titania were also possible. Regularly porous nanostructured platinum substrate also permitted development of submicro ‘reactors’ where reactant molecules, electrolyte ions, and all active components (TiO2 or WO3, Pt substrate, PtRu catalytic sites) could co-exist and become easily accessible. While WO3 was able to undergo fast reversible redox transitions to non-stoichiometric oxides, efficient utilization of inert (non-electroactive) TiO2 required admixing with carbon nanotubes to ensure easy charge distribution and good conductivity at the electrocatalytic interface.
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Ignacio-de Leon PA, Cichelli JA, Abelow AE, Zharov I. Pore-Filled Nanoporous Silica Colloidal Films with Enantioselective Permeability. Z Anorg Allg Chem 2013. [DOI: 10.1002/zaac.201300408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Panja D, Barkema GT, Kolomeisky AB. Through the eye of the needle: recent advances in understanding biopolymer translocation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:413101. [PMID: 24025200 DOI: 10.1088/0953-8984/25/41/413101] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In recent years polymer translocation, i.e., transport of polymeric molecules through nanometer-sized pores and channels embedded in membranes, has witnessed strong advances. It is now possible to observe single-molecule polymer dynamics during the motion through channels with unprecedented spatial and temporal resolution. These striking experimental studies have stimulated many theoretical developments. In this short theory-experiment review, we discuss recent progress in this field with a strong focus on non-equilibrium aspects of polymer dynamics during the translocation process.
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Affiliation(s)
- Debabrata Panja
- Institute for Theoretical Physics, Universiteit Utrecht, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands. Institute for Theoretical Physics, Universiteit van Amsterdam, Science Park 904, Postbus 94485, 1090 GL Amsterdam, The Netherlands
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Mousavi MPS, Bühlmann P. Reference Electrodes with Salt Bridges Contained in Nanoporous Glass: An Underappreciated Source of Error. Anal Chem 2013; 85:8895-901. [DOI: 10.1021/ac402170u] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maral P. S. Mousavi
- Department of Chemistry, University of Minnesota, 207 Pleasant
Street South East, Minneapolis, Minnesota 55455, United States
| | - Philippe Bühlmann
- Department of Chemistry, University of Minnesota, 207 Pleasant
Street South East, Minneapolis, Minnesota 55455, United States
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13
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Fast screening of ketamine in biological samples based on molecularly imprinted photonic hydrogels. Anal Chim Acta 2013; 771:86-94. [DOI: 10.1016/j.aca.2013.01.055] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 01/24/2013] [Accepted: 01/28/2013] [Indexed: 11/23/2022]
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Abelow AE, White RJ, Plaxco KW, Zharov I. Nanoporous silica colloidal films with molecular transport gated by aptamers responsive to small molecules. ACTA ACUST UNITED AC 2011. [DOI: 10.1135/cccc2011022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We report the preparation of colloidal nanoporous silica films whose function mimics that of protein channels in gating the transport of small molecules across a cell membrane. Specifically, we report a means of controlling the molecular flux through colloidal nanopores that employ aptamer oligonucleotides binding to a specific organic small molecule (cocaine). These biomacromolecules have been introduced onto the nanopore surface by attaching pre-made oligonucleotides to the activated nanopore surface. The aptamers change their conformation in response to the binding events, and thus alter the free volume of the colloidal nanopores available for molecular transport.
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Dimos MM, Blanchard G. Electro-catalytic oxidation of 1,2-propanediol at nanoporous and planar solid Pt electrodes. J Electroanal Chem (Lausanne) 2011. [DOI: 10.1016/j.jelechem.2011.01.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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de la Escosura-Muñiz A, Merkoçi A. A nanochannel/nanoparticle-based filtering and sensing platform for direct detection of a cancer biomarker in blood. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2011; 7:675-682. [PMID: 21294272 DOI: 10.1002/smll.201002349] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Indexed: 05/30/2023]
Abstract
A rapid nanochannel-based immunoassay capable of the filtering and subsequent detection of proteins in whole blood without any sample preparation is described. This is accomplished by using a nanoporous/nanochannel membrane modified with antibodies, the conductivity of which toward a redox indicator is tuned by primary and secondary immunoreactions with proteins and gold nanoparticles. This interesting nanopore blockage by gold nanoparticles is enhanced by silver deposition that further decreases the diffusion of the signaling indicator through the nanochannel. The efficiency of the nanochannels to act as immunoreaction platforms including the use of nanoparticles is also monitored by microscopic techniques. Successful detection of immunoglobulins including a cancer biomarker is achieved in buffer as well as in whole blood. This system constitutes an efficient immunoassay capable of detecting up to 52 U mL(-1) of CA15-3. The developed nanochannel/nanoparticle-based device can be used for several other proteins and extended also to DNA detection with interest not only for diagnostics but also environmental monitoring, food analysis, safety, and security applications.
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Affiliation(s)
- Alfredo de la Escosura-Muñiz
- Nanobioelectronics & Biosensors Group, CIN2 (ICN-CSIC), Catalan Institute of Nanotechnology, Campus de la UAB Bellaterra, Barcelona 08193, Spain
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Ignacio-de Leon PAA, Zharov I. Size-selective molecular transport through silica colloidal nanopores. Chem Commun (Camb) 2010; 47:553-5. [PMID: 21103608 DOI: 10.1039/c0cc02101f] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diffusion rate of dye-labelled PAMAM dendrimers through free-standing silica colloidal crystals was studied as a function of the dendrimer generation and nanopore size to determine the transport selectivity.
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Abelow AE, Schepelina O, White RJ, Vallée-Bélisle A, Plaxco KW, Zharov I. Biomimetic glass nanopores employing aptamer gates responsive to a small molecule. Chem Commun (Camb) 2010; 46:7984-6. [PMID: 20865192 DOI: 10.1039/c0cc02649b] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the preparation of 20 and 65 nm radii glass nanopores whose surface is modified with DNA aptamers controlling the molecular transport through the nanopores in response to small molecule binding.
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Affiliation(s)
- Alexis E Abelow
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, USA
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Cherdhirankorn T, Retsch M, Jonas U, Butt HJ, Koynov K. Tracer diffusion in silica inverse opals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:10141-10146. [PMID: 20232884 DOI: 10.1021/la1002572] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We employed fluorescence correlation spectroscopy (FCS) to study the diffusion of small fluorescence tracers in liquid filled silica inverse opals. The inverse opals consisted of a nanoporous silica scaffold spanning a hexagonal crystal of spherical voids of 360 nm diameter connected by circular pores of 70 nm diameter. The diffusion of Alexa Fluor 488 in water and of perylene-3,4,9,10-tetracarboxylic diimide (PDI) in toluene was studied. Three diffusion modes could be distinguished: (1) Free diffusion limited by the geometric constraints given by the inverse opal, where, as compared to the free solution, this diffusion is slowed down by a factor of 3-4, (2) slow diffusion inside the nanoporous matrix of the silica scaffold, and (3) diffusion limited by adsorption. On the length scale of the focus of a confocal microscope of roughly 400 nm diffusion was non-Fickian in all cases.
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Brozek EM, Zharov I. Internal Functionalization and Surface Modification of Vinylsilsesquioxane Nanoparticles. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2010; 21:1451-1456. [PMID: 20046982 PMCID: PMC2699302 DOI: 10.1021/cm801894w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The interior of 237 nm spherical vinylsilsesquioxane nanoparticles has been covalently modified and their surface functionalized under mild conditions to yield a novel type of hybrid silsesquioxane nanoparticles. Data obtained from thermogravimetric and elemental analysis show that the vinyl groups inside the nanoparticles can be easily brominated or hydroborated, leading to the nanoparticles containing 59.9 wt% of bromine or 3.6 wt% of boron, respectively. Our results demonstrate that the vinyl groups inside the nanoparticles are highly accessible, which may lead to the preparation of a host of hybrid organosilica nanoparticles with complex structures. We also show that the surface of the brominated and boronated nanoparticles is unhindered for further amination.
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Affiliation(s)
- Eric M. Brozek
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Ilya Zharov
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
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Sawangphruk M, Foord JS. Permselective properties of polystyrene opal films at diamond electrode surfaces. Phys Chem Chem Phys 2010; 12:7856-64. [DOI: 10.1039/b926005f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Calvo A, Yameen B, Williams FJ, Soler-Illia GJ, Azzaroni O. Mesoporous Films and Polymer Brushes Helping Each Other To Modulate Ionic Transport in Nanoconfined Environments. An Interesting Example of Synergism in Functional Hybrid Assemblies. J Am Chem Soc 2009; 131:10866-8. [DOI: 10.1021/ja9031067] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alejandra Calvo
- Gerencia de Química, CNEA, Centro Atómico Constituyentes, Av. Gral. Paz 1499, San Martín B1650KNA, Argentina, Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, Departamento de Química de Superficies y Recubrimientos, TENARIS, Simini 250, B2804MHA Campana, Argentina, and Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)-CONICET, Universidad Nacional de La Plata, CC 16 Sucursal 4 (1900) La Plata, Argentina
| | - Basit Yameen
- Gerencia de Química, CNEA, Centro Atómico Constituyentes, Av. Gral. Paz 1499, San Martín B1650KNA, Argentina, Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, Departamento de Química de Superficies y Recubrimientos, TENARIS, Simini 250, B2804MHA Campana, Argentina, and Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)-CONICET, Universidad Nacional de La Plata, CC 16 Sucursal 4 (1900) La Plata, Argentina
| | - Federico J. Williams
- Gerencia de Química, CNEA, Centro Atómico Constituyentes, Av. Gral. Paz 1499, San Martín B1650KNA, Argentina, Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, Departamento de Química de Superficies y Recubrimientos, TENARIS, Simini 250, B2804MHA Campana, Argentina, and Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)-CONICET, Universidad Nacional de La Plata, CC 16 Sucursal 4 (1900) La Plata, Argentina
| | - Galo J.A.A. Soler-Illia
- Gerencia de Química, CNEA, Centro Atómico Constituyentes, Av. Gral. Paz 1499, San Martín B1650KNA, Argentina, Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, Departamento de Química de Superficies y Recubrimientos, TENARIS, Simini 250, B2804MHA Campana, Argentina, and Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)-CONICET, Universidad Nacional de La Plata, CC 16 Sucursal 4 (1900) La Plata, Argentina
| | - Omar Azzaroni
- Gerencia de Química, CNEA, Centro Atómico Constituyentes, Av. Gral. Paz 1499, San Martín B1650KNA, Argentina, Max-Planck-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, Departamento de Química de Superficies y Recubrimientos, TENARIS, Simini 250, B2804MHA Campana, Argentina, and Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)-CONICET, Universidad Nacional de La Plata, CC 16 Sucursal 4 (1900) La Plata, Argentina
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24
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Bohaty AK, Smith JJ, Zharov I. Free-standing silica colloidal nanoporous membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3096-3101. [PMID: 19437715 DOI: 10.1021/la801922a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We prepared robust free-standing 200 microm-thick colloidal membranes (nanofrits) with a relatively large area and no mechanical defects by sintering silica colloidal films. The silica spheres used to prepare the nanofrits were 338, 300, or 251 nm in diameter, leading to 25, 22.5, and 19 nm nanopore sizes, respectively. The room-temperature diffusional flux through these membranes is of the order of 3.6 x 10(-10) mol s(-1) cm(-2) for a Fe(bpy)32+ ion in acetonitrile test solution in the absence of applied pressure and is in good agreement with the calculated diffusional flux for colloidal crystals of the same thickness. To evaluate the feasibility of nanofrit surface modification, we treated them with 3-aminopropyltriethoxysilane after rehydroxylation. We found, by measuring the surface coverage for dansyl amide on the surface, that the number of the amines on the nanofrit surface is lower as compared to that observed for colloidal films not treated with heat. As a result, the selectivity for the transport of Fe(bpy)3(2+) through the aminated nanofrits in the presence of acid is lower than the selectivity observed for amine-modified colloidal films.
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Affiliation(s)
- Andrew K Bohaty
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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25
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Calvo A, Yameen B, Williams FJ, Azzaroni O, Soler-Illia GJAA. Facile molecular design of hybrid functional assemblies with controllable transport properties: mesoporous films meet polyelectrolyte brushes. Chem Commun (Camb) 2009:2553-5. [DOI: 10.1039/b822489g] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Zelcer A, Wolosiuk A, Soler-Illia GJAA. Carbonaceous submicron sized islands: a surface patterning route to hierarchical macro/mesoporous thin films. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b902378j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Schepelina O, Zharov I. Poly(2-(dimethylamino)ethyl methacrylate)-modified nanoporous Colloidal films with pH and ion response. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:14188-14194. [PMID: 19053656 DOI: 10.1021/la802453z] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes were grown using surface-initiated atom transfer radical polymerization on the nanopore surface inside the colloidal films assembled from 255 nm silica spheres. The molecular transport through PDMAEMA-modified colloidal nanopores was studied as a function of pH and ionic strength by measuring the flux of neutral and positively charged redox-active species across the colloidal films using cyclic voltammetry. Nanopores modified with PDMAEMA brushes exhibited pH- and ion-dependent behavior as follows. The diffusion rates decreased with decreasing pH as a result of electrostatic interactions and steric hindrance. At low pH (in the protonated state) the diffusion rates increased with increasing salt concentration because of the charge screening. We also quaternized the surface-grafted PDMAEMA, which led to the formation of strong polyelectrolyte brushes that hindered the diffusion of neutral molecules through the nanopores due to steric effects and the diffusion of positively charged species due to both electrostatic and steric effects.
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Affiliation(s)
- Olga Schepelina
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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28
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Brewer DD, Allen J, Miller MR, de Santos JM, Kumar S, Norris DJ, Tsapatsis M, Scriven LE. Mechanistic principles of colloidal crystal growth by evaporation-induced convective steering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:13683-13693. [PMID: 18989941 DOI: 10.1021/la802180d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We simulate evaporation-driven self-assembly of colloidal crystals using an equivalent network model. Relationships between a regular hexagonally close-packed array of hard, monodisperse spheres, the associated pore space, and selectivity mechanisms for face-centered cubic microstructure propagation are described. By accounting for contact line rearrangement and evaporation at a series of exposed menisci, the equivalent network model describes creeping flow of solvent into and through a rigid colloidal crystal. Observations concerning colloidal crystal growth are interpreted in terms of the convective steering hypothesis, which posits that solvent flow into and through the pore space of the crystal may play a major role in colloidal self-assembly. Aspects of the convective steering and deposition of high-Peclet-number rigid spherical particles at a crystal boundary are inferred from spatially resolved solvent flow into the crystal. Gradients in local flow through boundary channels were predicted due to the channels' spatial distribution relative to a pinned free surface contact line. On the basis of a uniform solvent and particle flux as the criterion for stability of a particular growth plane, these network simulations suggest the stability of a declining {311} crystal interface, a symmetry plane which exclusively propagates fcc microstructure. Network simulations of alternate crystal planes suggest preferential growth front evolution to the declining {311} interface, in consistent agreement with the proposed stability mechanism for preferential fcc microstructure propagation in convective assembly.
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Affiliation(s)
- Damien D Brewer
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455-0132, USA.
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29
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Huang XJ, Li Y, Choi YK. A chestnut-like hierarchical architecture of a SWCNT/microsphere composite on an electrode for electroanalysis. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.01.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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30
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Smith JJ, Zharov I. Ion transport in sulfonated nanoporous colloidal films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:2650-2654. [PMID: 18275224 DOI: 10.1021/la7013072] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The surface of self-assembled nanoporous silica colloidal crystalline films comprised of 184-nm-diameter silica spheres has been sulfonated using 1,3-propanesultone. The transport of ions through the sulfonated films has been studied using cyclic voltammetry in water as a function of ion charge, pH, and solution ionic strength. We found that the flux of anions through the sulfonated colloidal films is reduced, while the flux of cations is increased, compared to the unmodified colloidal films. This behavior is pH-dependent and is due to electrostatic repulsion/attraction that can be modulated by changing the ionic strength of the contacting solution.
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Affiliation(s)
- Joanna J Smith
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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31
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Smith JJ, Abbaraju RR, Zharov I. Proton transport in assemblies of silica colloidal spheres. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b807419d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Schepelina O, Zharov I. PNIPAAM-modified nanoporous colloidal films with positive and negative temperature gating. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:12704-9. [PMID: 17975940 DOI: 10.1021/la702008j] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The surface of nanopores in colloidal films, assembled from 205 nm silica spheres, was modified with poly(N-isopropylacrylamide), PNIPAAM, brushes using surface-initiated ATRP. The polymer thickness inside nanopores was controlled by the polymerization time. The diffusion through PNIPAAM-modified colloidal films was measured using cyclic voltammetry and studied as a function of temperature and polymer brush thickness. Nanopores modified with a thin PNIPAAM brush exhibited a positive gating behavior, where diffusion rates increased with increasing temperature. Nanopores modified with a thick PNIPAAM layer showed a negative gating behavior where diffusion rates decreased with increasing temperature. The observed temperature response is consistent with two transport mechanisms, one in which molecules diffuse through the nanopores whose volume increases with increasing temperature as the PNIPAAM brush collapses onto the nanopore surface (positive gating) and the second one where molecules diffuse through the porous PNIPAAM that fills the entire nanopore opening and collapses onto itself, becoming hydrophobic and impermeable (negative gating).
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Affiliation(s)
- Olga Schepelina
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
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33
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Snyder MA, Lee JA, Davis TM, Scriven LE, Tsapatsis M. Silica nanoparticle crystals and ordered coatings using lys-sil and a novel coating device. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:9924-8. [PMID: 17625899 DOI: 10.1021/la701063v] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Silica nanoparticles with a narrow particle size distribution and controlled diameters of 10-20 nm are synthesized via hydrolysis and hydrothermal aging of tetraethylorthosilicate in an aqueous L-lysine solution. Cryo-transmission electron microscopy (cryo-TEM) reveals that the silica nanoparticles assemble to form close-packed nanoparticle crystals over short length scales on carbon-coated grids. Evaporative drying of the same sols results in nanoparticle stability and remarkable long-range facile ordering of the silica nanoparticles over scales greater than 10 microm. Whereas small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) discount the possibility of a core (silica)-shell (lysine) structure, the possibility remains for lysine occlusion within the silica nanoparticles and concomitant hydrogen bonding effects driving self-assembly. Facile ordering of the silica nanoparticles into multilayer and monolayer coatings over square-centimeter areas by evaporation-induced self-assembly is demonstrated using a novel dip-coating device.
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Affiliation(s)
- Mark A Snyder
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Cichelli J, Zharov I. Chiral permselectivity in nanoporous opal films surface-modified with chiral selector moieties. ACTA ACUST UNITED AC 2007. [DOI: 10.1039/b617607k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Schepelina O, Zharov I. Polymer-modified opal nanopores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:10523-7. [PMID: 17129025 DOI: 10.1021/la061170d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The surface of nanopores in opal films, assembled from 205 nm silica spheres, was modified with poly(acrylamide) brushes using surface-initiated atom transfer radical polymerization. The colloidal crystal lattice remained unperturbed by the polymerization. The polymer brush thickness was controlled by polymerization time and was monitored by measuring the flux of redox species across the opal film using cyclic voltammetry. The nanopore size and polymer brush thickness were calculated on the basis of the limiting current change. Polymer brush thickness increased over the course of 26 h of polymerization in a logarithmic manner from 1.3 to 8.5 nm, leading to nanopores as small as 7.5 nm.
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Affiliation(s)
- Olga Schepelina
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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36
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Wang G, Bohaty AK, Zharov I, White HS. Photon Gated Transport at the Glass Nanopore Electrode. J Am Chem Soc 2006; 128:13553-8. [PMID: 17031969 DOI: 10.1021/ja064274j] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interior surface of the glass nanopore electrode was modified with spiropyran moieties to impart photochemical control of molecular transport through the pore orifice (15-90 nm radius). In low ionic strength acetonitrile solutions, diffusion of a positively charged species (Fe(bpy)(3)(2+)) is electrostatically blocked with approximately 100% efficiency by UV light-induced conversion of the neutral surface-bound spiropyran to its protonated merocyanine form (MEH+). Transport through the pore orifice is restored by either irradiation of the electrode with visible light to convert MEH+ back to spiropyran or addition of a sufficient quantity of supporting electrolyte to screen the electrostatic field associated with MEH+. The transport of neutral redox species through spiropyran-modified glass nanopores is not affected by light, allowing photoselective transport of redox molecules to the electrode surface based on charge discrimination. The glass nanopore electrode can also be employed as a photochemical trap, by UV light conversion of surface-bound spiropyran to MEH+, preventing Fe(bpy)(3)(2+) initially in the pore from diffusing through the orifice.
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Affiliation(s)
- Gangli Wang
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, UT 84112, USA
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37
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Bohaty AK, Zharov I. Suspended self-assembled opal membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:5533-6. [PMID: 16768467 DOI: 10.1021/la0602463] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Suspended self-assembled opal membranes have been prepared from 440- or 170-nm-diameter silica spheres by evaporation of their colloidal solutions over vertically oriented 0.3-mm-thick silicon wafers containing frustum-shaped openings. Robust 0.5 x 0.5 mm(2) membranes with a thickness of ca. 300 mum have been reproducibly prepared using 170 nm silica spheres. The membranes show regular fcc packing with an exposed (111) orientation and are formed in a process that involves drawing silica spheres into the opening with the solvent meniscus.
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Affiliation(s)
- Andrew K Bohaty
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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38
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Abstract
Nanoporous 7 mum thin opal films comprising 35 layers of 200 nm diameter SiO2 spheres were assembled on Pt electrodes and modified with chiral selector moieties on the silica surface. Diffusion of chiral redox species through the opals was studied by cyclic voltammetry. The chiral opal films demonstrate high selectivity for transport of one enantiomer over the other. This chiral permselectivity is attributed to the surface-facilitated transport utilizing noncovalent interactions between the chiral permeant molecules and surface-bound chiral selectors.
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Affiliation(s)
- Julie Cichelli
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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