scholarly journals Effect of Humidity and Hydrophobicity on the Tribological Properties of Self-Assembled Monolayers

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Yen-Chih Liao ◽  
William Hargrove ◽  
Brandon L. Weeks
Keyword(s):  
Tribological Properties ◽  
Lateral Force ◽  
Bulk Water ◽  
Self Assembled Monolayers ◽  
Lateral Force Microscopy ◽  
Force Microscopy ◽  
Gold Substrates ◽  
Assembled Monolayers ◽  
Force Signal ◽  
The Difference

The tribological properties of two distinctive alkanethiol SAMs, 16-mercaptohexadecanoic acid (MHA) and 1-octadecanethiol (ODT), on gold substrates in various humidity conditions were examined by lateral force microscopy (LFM). The results suggest that hydrophobic ODT SAM is insensitive to humidity. The difference of lateral force signal is within ±10% regardless of humidity. The lateral force signal of hydrophilic MHA SAMs has a significant decrease in signal in humid environments. The influence of bulk water was also investigated by LFM. By imaging under water, the capillary force is eliminated on ODT SAMs, which leads to a lower lateral force. However, the lateral force image was reversed on MHA SAMs, which suggested that hydrophobic forces dominated in water.

Compositional Mapping of Micropatterned, Mixed Self-Assembled Monolayers by Lateral Force Microscopy

Langmuir ◽  
1998 ◽  
Vol 14 (3) ◽  
pp. 660-666 ◽  
Author(s):  
Yuqing Zhou ◽  
Hongyou Fan ◽  
Tommy Fong ◽  
Gabriel P. Lopez
Keyword(s):  
Lateral Force ◽  
Self Assembled Monolayers ◽  
Lateral Force Microscopy ◽  
Force Microscopy ◽  
Assembled Monolayers ◽  
Self Assembled

Preparation, Characterization, and Electrical Properties of a Self-Assembled meso-Pyridyl Porphyrin Monolayer on Gold Surfaces

2005 ◽  
Vol 58 (11) ◽  
pp. 810 ◽  
Author(s):  
Amarchand Sathyapalan ◽  
Anup Lohani ◽  
Sangita Santra ◽  
Saurabh Goyal ◽  
M. Ravikanth ◽  
...  
Keyword(s):  
Soret Band ◽  
Gold Surface ◽  
Scanning Tunneling Spectroscopy ◽  
Uv Absorption ◽  
Self Assembled Monolayers ◽  
Scanning Tunneling ◽  
Force Microscopy ◽  
Gold Substrates ◽  
Assembled Monolayers ◽  
Self Assembled

A meso-pyridyl porphyrin, 5-(4-(2-(4-(S-acetylthiomethyl)phenyl)ethynyl)phenyl)-10,15,20-tris(4-pyridyl) porphyrin was synthesized by coupling of 5-{4-ethynyl}phenyl-10,15,20-tris(4-pyridyl) porphyrin with 4-(S-acetylthiomethyl)-4-iodobenzene under mild palladium coupling conditions. The meso-pyridyl porphyrin was used for the preparation of self assembled monolayers on gold substrates. The gold substrates were made by the thermal evaporation of gold on oxidized Si(100) surfaces. The self-assembled monolayers (SAMs) were characterized using ground state UV absorption and X-ray photoelectron spectroscopic (XPS) techniques and also by scanning probe microscopy (SPM) techniques. The UV-absorption spectra of the porphyrin monolayer exhibited a 10 nm red shift in the Soret band compared to the porphyrin in CHCl3 solution. This indicates that the porphyrin molecules are aligned on the gold substrate in a side-by-side orientation. The typical shifts in the binding energy by XPS revealed that the chemisorption of the thiolate species of the porphyrin to the surface occurs through a strong sulfur–gold bonding mechanism. Basic hexagonal (√3×√3) R 30° well ordered self-assembled monolayers of meso-pyridyl porphyrin was observed by molecular-resolution atomic force microscopy (AFM). Room temperature current–voltage (I–V) spectra by scanning tunneling spectroscopy (STS) at varying set point current were collected to study the electronic transport properties of the monolayers on the gold surface.

In-Silico Prediction on the MSAMS-Assisted Immobilization of Bovine Serum Albumin on 10MHz Piezoelectric Immunosensors

2019 ◽  
Vol 07 (01n02) ◽  
pp. 1950001 ◽  
Author(s):  
Kaory Barrientos Urdinola ◽  
Paula Andrea Marín Muñoz ◽  
Pedronel Araque Marín ◽  
Marisol Jaramillo Grajales
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Molecular Model ◽  
Self Assembled Monolayers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Gold Substrates ◽  
Assembled Monolayers ◽  
Sensitivity Specificity

The biological sensing interface on the active area of a piezo transducer is responsible for the sensitivity, specificity, reusability, and reproducibility of these devices. Among the approaches used to functionalize piezo transducers, mixed self-assembled monolayers (MSAMs) are one of the most successful, given that they allow the obtaining of semi-crystalline molecular arrays and the arrangement of a bioreceptor on the surface. But, to deploy MSAMs on a substrate effectively, one must optimize and characterize the structural ratio between them and the bioreceptor. In this paper, we developed a molecular model of the interaction between Bovine Serum Albumin (BSA) and MSAMs-functionalized gold substrates. First, we evaluated the conditions for the functionalization of the substrates and found that a 50:1 16-mercaptohexadecaonic acid (MHDA) to 11 mercapto-1-undecanol (MUA) ratio produced the best features on the surface. We also evaluated the specific conditions to immobilize BSA on MSAMs (using the afore-established ratio) via Atomic Force Microscopy (AFM), and then on a 10[Formula: see text]MHz quartz crystal microbalance (QCM), and with the data obtained we concluded that a structural ratio of 0.005 (MSAM/BSA) is obtained when 1[Formula: see text][Formula: see text]M MHDA and 200[Formula: see text][Formula: see text]g/mL BSA were used, provided the most suitable conditions for the functionalization of a piezo transducer.

scholarly journals Protein- and Cell-Resistance of Zwitterionic Peptide-Based Self-Assembled Monolayers: Anti-Biofouling Tests and Surface Force Analysis

2021 ◽  
Vol 9 ◽  
Author(s):  
Ryongsok Chang ◽  
Evan Angelo Quimada Mondarte ◽  
Debabrata Palai ◽  
Taito Sekine ◽  
Aki Kashiwazaki ◽  
...  
Keyword(s):  
Surface Force ◽  
Amino Acid Sequences ◽  
Self Assembled Monolayers ◽  
Clear Correlation ◽  
Interfacial Water ◽  
Cell Resistance ◽  
Force Microscopy ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
The Difference

Peptide-based self-assembled monolayers (peptide-SAMs) with specific zwitterionic amino acid sequences express an anti-biofouling property. In this work, we performed protein adsorption and cell adhesion tests using peptide-SAMs with repeating units of various zwitterionic pairs of amino acids (EK, DK, ER, and DR). The SAMs with the repeating units of EK and DK (EK and DK SAMs) manifested excellent bioinertness, whereas the SAMs with the repeating units of ER and DR (ER and DR SAMs) adhered proteins and cells. We also performed surface force measurements using atomic force microscopy to elucidate the mechanism underlying the difference in the anti-biofouling property. Our measurements revealed that water-induced repulsion with a range of about 8 nm acts between EK SAMs (immobilized on both probe and substrate) and DK SAMs, whereas such repulsion was not observed for ER and DR SAMs. The strength of the repulsion exhibited a clear correlation with the protein- and cell-resistance of the SAMs, indicating that the interfacial water in the vicinity of EK and DK SAMs is considered as a physical barrier to deter protein and cells from their adsorption or adhesion. The range of the repulsion observed for EK and DK SAMs is longer than 8 nm, indicating that the hydrogen bonding state of the interfacial water with a thickness of 4 nm is modified by EK and DK SAMs, resulting in the expression of the anti-biofouling property.

Nanoporous Thin Films Formed from Photocleavable Diblock Copolymers on Gold Substrates Modified with Thiolate Self-Assembled Monolayers

Langmuir ◽  
2020 ◽  
Vol 36 (31) ◽  
pp. 9259-9268 ◽  
Author(s):  
Takashi Ito ◽  
Herman Coceancigh ◽  
Yi Yi ◽  
Jay N. Sharma ◽  
Fred C. Parks ◽  
...  
Keyword(s):  
Thin Films ◽  
Diblock Copolymers ◽  
Self Assembled Monolayers ◽  
Gold Substrates ◽  
Assembled Monolayers ◽  
Self Assembled
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