Switchable Assembly of Stable, Ordered Molecular Layers

Auer, Frank; Schubert, Dirk W.; Stamm, Manfred; Arnebrant, Thomas; Swietlow, Aleksander; Zizlsperger, Manfred; Sellergren, Börje

doi:10.1002/(sici)1521-3765(19990401)5:4<1150::aid-chem1150>3.0.co;2-5

Cited by 20 publications

(36 citation statements)

References 22 publications

(32 reference statements)

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“…On the least ordered SAM (MUA), the thickness increases continuously with increasing amphiphile chain length. Thus, for n = 7, the thickness corresponds to a monolayer of molecules oriented with their alkyl chains nearly perpendicular to the surface, whereas an increasing tendency for bilayer formation is seen with increasing chain length 9. This contrasts with the behavior on the more ordered SAMs of MPA and MHA.…”

Section: Resultsmentioning

confidence: 84%

“… [a] Ellipsometry was performed on dry surfaces in air and the thickness was calculated assuming a layer refractive index of 1.45. The neutron reflectivity was measured in D 2 O as previously described9 with a specially designed cuvette. The molecular length was estimated assuming an extended conformation of all‐ trans alkyl chains.…”

Section: Resultsmentioning

confidence: 99%

“…Substrates : The preparation of the gold substrates and the thiol SAMs followed, with a few exceptions, previously described procedures 9. The substrates for ellipsometry and IRAS were prepared by vapor deposition of gold (2000 Å thickness) onto glass slides or silicon wafers containing adhesive layers (300 Å) of chromium or titanium.…”

Section: Methodsmentioning

confidence: 99%

“…8 Ordered multimolecular assemblies that can be repeatedly formed and destabilized on a practical timescale have been reported only rarely in the literature 8. 9 Recently, we showed that bola‐amphiphiles of the type α , ω ‐bis(4‐amidinophenoxy)alkanes assemble spontaneously and rapidly on SAMs of mercaptoalkanoic acids on gold or on pure gold substrates (Scheme ) 9. Conditions could be found that allow repeated assembly–test–disassembly cycles of the layer structure.…”

Section: Introductionmentioning

confidence: 99%

“…Conditions could be found that allow repeated assembly–test–disassembly cycles of the layer structure. This restorable substrate concept was demonstrated for the detection of single mismatches in DNA hybridization experiments10 for selective detection of phosphate‐containing biomolecules,11 for the charge‐selective adsorption of plasma proteins,9 and for the rapid formation of dense layers of gold nanoparticles 12. After the “sensing” or adsorption event, the layers could be destabilized and the substrate restored.…”

Section: Introductionmentioning

confidence: 99%

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Odd–Even Chain Length‐Dependent Order in pH‐Switchable Self‐Assembled Layers

Auer¹,

Nelles

Sellergren

2004

Chemistry A European J

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The reversible self-assembly of a series of bipolar amphiphiles, alpha,omega-bis(3- or 4-amidinophenoxy)alkanes (chain length n = 5-12), on mercaptoalkanoic acid-functionalized gold surfaces (chain length n = 10, 11, 14, 15) has been studied by in-situ ellipsometry, IR reflection absorption spectroscopy (IRAS), and atomic force microscopy (AFM). The layer order, amphiphile orientation, and tendency to form bilayers depends on the position of the amidine substituent, the alkyl chain length of both the amidine amphiphile and the underlying acid self-assembled monolayer (SAM), and whether the amidine alkyl chain contained an even or odd number of methylene groups. Thus, para-substituted bisbenzamidines containing more than six methylene groups (n>6) and with an odd number (n = 7, 9, 11) tended to form bilayered structures, whereas those containing an even number formed monolayers when adsorbed on SAMs of the long-chain acids (n = 14, 15). This behavior also correlated with the average tilt angle of the benzene moieties of the amphiphiles, as estimated by IRAS. The odd-numbered chains gave lower tilt angles than the even-numbered ones, and a possible model that accounts for these results is proposed. IRAS also revealed a higher order of the odd-numbered chains and an increasing hydrogen-bonding contribution with increasing chain length. Additional evidence for the proposed bilayered assemblies and their reversibility was obtained by AFM. Images obtained from the assembly of decamidine on a SAM of mercaptohexadecanoic acid in a pH 9 borate buffer revealed domains of similar size to that of the underlying acid SAM (20-30 nm), but less densely packed. By acidifying the solution, the second layer was destabilized and a very smooth layer with few defects appeared. Further acidification to pH 3 also destabilized the first layer.

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Section: Resultsmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Odd–Even Chain Length‐Dependent Order in pH‐Switchable Self‐Assembled Layers

Auer¹,

Nelles

Sellergren

2004

Chemistry A European J

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Stimuli‐Responsive Monolayers

Scaramuzzo¹,

Barteri²,

Jonkheijm³

et al. 2013

Organic Nanomaterials

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Stimuli‐Responsive Surfaces in Biomedical Applications

Pranzetti¹,

Preece²,

Mendes³

2013

Intelligent Stimuli‐Responsive Materials

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Nature provides mechanisms that are able to dynamically control specific and nonspecific interactions between cells and biological surfaces [1,2]. Scientists have long tried to reproduce these dynamic biological events and have recently made an important step in that direction by creating artificial stimuli-responsive surfaces [3][4][5][6][7]. These smart substrates present modulatory surface properties that are able to respond to external chemical/biochemical [8][9][10][11][12], thermal [13][14][15], electrical [16][17][18][19][20], and optical stimuli [21][22][23][24][25][26][27][28][29][30][31]. Due to their dynamic nature such substrates are very appealing for applications in the biomedical field [32]. Progress to date has led to control over biomolecule activity [33] and immobilization of a diverse array of proteins, including enzymes [34] and antibodies [35]. These prior achievements have encouraged researchers to take the challenge of using dynamic surfaces to modulate larger and more complex systems, such as bacteria [36] and mammalian cells [37].Achieving control over surface properties could provide new insights in the understanding of cell behavior and can offer distinct benefits with regard to the development of medical devices. For instance, the modulation of cell attachment and detachment could lead to the prevention of unwanted bacteria fouling on implants, reducing the risk of infections and rejection [38][39][40][41][42]. Furthermore, dynamic surfaces able to present on demand regulatory signals to a cell could provide unprecedented opportunities in studies of cell responses in real-time. Cells in tissues adhere to and interact with their extracellular environment via specialized cell-cell and cell-extracellular

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Switchable Assembly of Stable, Ordered Molecular Layers

Cited by 20 publications

References 22 publications

Odd–Even Chain Length‐Dependent Order in pH‐Switchable Self‐Assembled Layers

Odd–Even Chain Length‐Dependent Order in pH‐Switchable Self‐Assembled Layers

Stimuli‐Responsive Monolayers

Stimuli‐Responsive Surfaces in Biomedical Applications

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