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Kulkarni SA, Lyles VD, Serem WK, Lu L, Kumar R, Garno JC. Solvent-responsive properties of octadecyltrichlorosiloxane nanostructures investigated using atomic force microscopy in liquid. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:5466-5473. [PMID: 24788214 DOI: 10.1021/la500799u] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
An emerging challenge for nanoscale measurements is to capture and quantify the magnitude of structural changes in response to environmental changes. Certain environmental parameters can affect the nanoscale morphology of samples, such as changing the pH, solvent polarity, ionic strength, and temperature. We prepared test platforms of n-octadecyltrichlorosilane ring nanostructures to study surface morphology changes at the nanoscale in selected liquid media compared to dry conditions in air. Particle lithography combined with organosilane vapor deposition was used to fabricate nanostructures of regular dimensions. Multilayer nanostructures of OTS were used as a test platform for scanning probe studies of solvent-responsive properties where the sides of designed ring structures expose a 3D interface for studying the interaction of solvents with molecular side groups. In dry, ambient conditions, nanostructures of OTS were first imaged using contact mode atomic force microscopy (AFM). Next, ethanol or buffer was introduced to the sample cell, and images were acquired using the same probe. We observed substantial changes in the lateral and vertical dimensions of the ring nanostructures in AFM topography frames; the sizes of the rings were observed to swell by tens of nanometers. Even after heat treatment of samples to promote cross-linking, the samples still evidenced swelling in liquid media. This research will have consequences for studies of the properties of nanomaterials, such as solvent-responsive organic films and polymers.
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Affiliation(s)
- Shalaka A Kulkarni
- Department of Chemistry, Louisiana State University , 232 Choppin Hall, Baton Rouge, Louisiana 70803, United States
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Zhang Z, Berns AE, Willbold S, Buitenhuis J. Synthesis of poly(ethylene glycol) (PEG)-grafted colloidal silica particles with improved stability in aqueous solvents. J Colloid Interface Sci 2007; 310:446-55. [PMID: 17346738 DOI: 10.1016/j.jcis.2007.02.024] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Revised: 01/15/2007] [Accepted: 02/02/2007] [Indexed: 11/18/2022]
Abstract
The known grafting procedures of colloidal silica particles with poly(ethylene glycol) (PEG) lead to grafting layers that detach from the silica surface and dissolve in water within a few days. We present a new grafting procedure of PEG onto silica with a significant improvement of the stability of the grafting layers in aqueous solvents. Moreover, the procedure avoids any dry states or other circumstances leading to strong aggregation of the particles. To achieve the improved water stability, Stöber silica particles are first pre-coated with a silane coupling agent (3-aminopropyl)triethoxysilane (APS) to incorporate active amine groups. The water solubility of the pre-coating layer was minimized using a combination of APS with bis-(trimethoxysilylpropyl)amine (BTMOSPA) or bis-(triethoxysilyl)ethane (BTEOSE). These pre-coated particles were then reacted with N-succinimidyl ester of mono-methoxy poly(ethylene glycol) carboxylic acid to form PEG-grafted silica particles. The particles form stable dispersions in aqueous solutions as well as several organic solvents.
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Affiliation(s)
- Zhenkun Zhang
- Forschungszentrum Jülich GmbH, IFF-Weiche Materie, D-52425 Jülich, Germany
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Reed J, Mishra B, Pittenger B, Magonov S, Troke J, Teitell MA, Gimzewski JK. Single molecule transcription profiling with AFM. NANOTECHNOLOGY 2007; 18:44032. [PMID: 20721301 PMCID: PMC2922717 DOI: 10.1088/0957-4484/18/4/044032] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Established techniques for global gene expression profiling, such as microarrays, face fundamental sensitivity constraints. Due to greatly increasing interest in examining minute samples from micro-dissected tissues, including single cells, unorthodox approaches, including molecular nanotechnologies, are being explored in this application. Here, we examine the use of single molecule, ordered restriction mapping, combined with AFM, to measure gene transcription levels from very low abundance samples. We frame the problem mathematically, using coding theory, and present an analysis of the critical error sources that may serve as a guide to designing future studies. We follow with experiments detailing the construction of high density, single molecule, ordered restriction maps from plasmids and from cDNA molecules, using two different enzymes, a result not previously reported. We discuss these results in the context of our calculations.
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Affiliation(s)
- Jason Reed
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA
| | - Bud Mishra
- Department of Computer Science and Mathematics, Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
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- Department of Pathology and the Center for Cell Control, an NIH Nanomedicine Development Center, UCLA, Los Angeles, CA 90095, USA
| | - Michael A Teitell
- Department of Pathology and the Center for Cell Control, an NIH Nanomedicine Development Center, UCLA, Los Angeles, CA 90095, USA
- California Nanosystems Institute (CNSI), Los Angeles, CA 90095, USA
| | - James K Gimzewski
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, CA 90095, USA
- California Nanosystems Institute (CNSI), Los Angeles, CA 90095, USA
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Yim H, Kent MS, Mendez S, Lopez GP, Satija S, Seo Y. Effects of Grafting Density and Molecular Weight on the Temperature-Dependent Conformational Change of Poly(N-isopropylacrylamide) Grafted Chains in Water. Macromolecules 2006. [DOI: 10.1021/ma0520949] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yim H, Kent MS, Tallant DR, Garcia MJ, Majewski J. Hygrothermal degradation of (3-glycidoxypropyl)trimethoxysilane films studied by neutron and X-ray reflectivity and attenuated total reflection infrared spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:4382-92. [PMID: 16032851 DOI: 10.1021/la0474870] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Thin films of organosilanes have great technological importance in the areas of adhesion promotion, durability, and corrosion resistance. However, it is well-known that water can degrade organosilane films, particularly at elevated temperatures. In this work, X-ray and neutron reflectivity (XR and NR) were combined with attenuated total reflection infrared (ATR-IR) spectroscopy to study the chemical and structural changes within thin films of (3-glycidoxypropyl)trimethoxysilane (GPS) after exposure for various periods of time to air saturated with either D2O or H2O at 80 degrees C. For NR and XR, ultrathin (approximately 100 A) films were prepared by spin-coating. Both D2O and H2O provide neutron scattering contrast with GPS. Variations in the neutron scattering length density (SLD) profiles (a function of mass density and atomic composition) with conditioning time were measured after drying the samples out and also swelled with H2O or D2O vapor at room temperature. For samples that were dried out prior to measurement, little or no change was observed for H2O conditioning up to 3.5 days, but large changes were observed after 30 days of conditioning. The range of conditioning time for this structural change was narrowed to between 4 and 10 days with XR. The SLD profiles indicated that the top portion of the GPS film was transformed into a thick low-density layer after conditioning, but the bottom portion showed little structural change. A previous NR study of as-prepared GPS films involving swelling with deuterated nitrobenzene showed that the central portion of the film has much lower cross-link density than the region nearest the substrate. The present data show that the central portion also swells to a much greater extent with water and hydrolyzes more rapidly. The chemical degradation mechanism was identified by IR as hydrolysis of siloxane bonds. For ATR-IR, GPS films were prepared by dip-coating, which resulted in a greater and more variable thickness than for the spin-coated samples. The IR spectra revealed an increase in vicinal silanol generation over the first 3 days of conditioning followed by geminal silanol generation. Thus, the structural change detected by NR and XR roughly coincided with the onset of geminal silanol generation. Finally, little change in the reflectivity data was observed for films conditioned with D2O at 80 degrees C for 1 month. This indicates that hydrolysis of Si-O-Si is much slower with D2O than with H2O.
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Affiliation(s)
- H Yim
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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Benkoski JJ, Kramer EJ, Yim H, Kent MS, Hall J. The effects of network structure on the resistance of silane coupling agent layers to water-assisted crack growth. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:3246-58. [PMID: 15875854 DOI: 10.1021/la035920k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Silane adhesion promoters are commonly used to improve the adhesion, durability, and corrosion resistance of polymer-oxide interfaces. The current study investigates a model interface consisting of the natural oxide of(100) Si and an epoxy cured from diglycidyl ether ofbisphenol A (DGEBA) and triethylenetetraamine (TETA). The thickness of (3-glycidoxypropyl)trimethoxysilane (GPS) films placed between the two materials provided the structural variable. Five surface treatments were investigated: a bare interface, a rough monolayer film, a smooth monolayer film, a 5 nm thick film, and a 10 nm thick film. Previous neutron reflection experiments revealed large extension ratios (>2) when the 5 and 10 nm thick GPS films were exposed to deuterated nitrobenzene vapor. Despite the larger extension ratio for the 5 nm thick film, the epoxy/Si fracture energy (Gc) was equal to that of the 10 nm thick film under ambient conditions. Even the smooth monolayer exhibited the same Gc. Only when the monolayer included a significant number of agglomerates did the Gc drop to levels closer to that of the bare interface. When immersed in water at room temperature for 1 week, the threshold energy release rate (Gth) was nearly equal to Gc for the smooth monolayer, 5 nm thick film, and 10 nm thick film. While the Gth for all three films decreased with increasing water temperature, the Gth of the smooth monolayer decreased more rapidly. The bare interface was similarly sensitive to temperature; however, the Gth of the rough monolayer did not change significantly as the temperature was raised. Despite the influence of pH on hydrolysis, the Gth was insensitive to the pH of the water for all surface treatments.
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Affiliation(s)
- J J Benkoski
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, USA
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Jeon H, Wyatt J, Harper-Nixon D, Weinkauf D. Characterization of thin polymer-like films formed by plasma polymerization of methylmethacrylate: A neutron reflectivity study. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/polb.20131] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Granick S, Kumar SK, Amis EJ, Antonietti M, Balazs AC, Chakraborty AK, Grest GS, Hawker C, Janmey P, Kramer EJ, Nuzzo R, Russell TP, Safinya CR. Macromolecules at surfaces: Research challenges and opportunities from tribology to biology. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/polb.10669] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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