Elaine Cooper

Growth of human osteoblast‐like cells on alkanethiol on gold self‐assembled monolayers: The effect of surface chemistry

Primary human osteoblasts were cultured on self-assembled monolayers (SAMs) of alkylthiols on gold with carboxylic acid and methyl termini, and the kinetics of cell attachment and proliferation were measured. Over 90 min approximately twice as many cells attached to carboxylic-acid-terminated monolayers as attached to methyl-terminated monolayers. After 24 h the number of cells attached to carboxylic-acid-terminated monolayers was ten times that attached to the methyl-terminated monolayers. Cell morphology and cytoskeletal actin organization also were found to be different. Osteoblasts were cultured on SAMs that were patterned by photolithographic techniques. Cells attached almost exclusively to carboxylic-acid-functionalized areas of the patterned surfaces, leaving methyl-functionalized regions bare. The patterns strongly influenced the morphology of the attached cells. After 24 h, cells were observed to bridge between carboxylic-acid-terminated regions separated by 75 microns, methyl-terminated regions but not those separated by 150 microns methyl-terminated regions. After 6 days in culture osteoblasts formed multilayers on the carboxylic-acid-terminated regions of the pattern.

Rates of attachment of fibroblasts to self-assembled monolayers formed by the adsorption of alkylthiols onto gold surfaces

Self-assembled monolayers (SAMs) of alkylthiols on gold surfaces have been prepared and characterised by contact angle goniometry and X-ray photoelectron spectroscopy. Murine 3T3 fibroblasts were cultured on single-component monolayers of adsorbates with carboxylic acid and methyl termini, and the rates of cellular attachment measured over 90 minutes. Cell attachment was found to be approximately twice as rapid for carboxylic acid-terminated monolayers as for methyl-terminated monolayers. After 24 hours, substantially greater numbers of 3T3 cells were found to be attached to the hydrophilic monolayers than were attached to the hydrophobic ones. Murine 3T3 cells were also cultured on patterned SAMs which were prepared using UV photochemistry and characterised using scanning electron microscopy. The cells attached exclusively to the acid-functionalised areas of the patterned surface, leaving the methyl-functionalised regions bare. The patterns also strongly influenced the morphology of the attached cells.

A comparative study of cell attachment to self assembled monolayers and plasma polymers

The first comparative study of cell attachment to self-assembled monolayers (SAMs) and plasma-deposited films is reported. Osteoblast-like cells attached extensively to acid-terminated alkyl thiol SAMs and to a plasma co-polymer of acrylic acid and octa-1,7-diene (acid-PCP). However, they attached poorly to methyl-terminated SAMs and a plasma polymer of octa-1,7-diene (OD-PP).

The effect of alkyl chain length and terminal group chemistry on the attachment and growth of murine 3T3 fibroblasts and primary human osteoblasts on self-assembled monolayers of alkanethiols on gold

Murine 3T3 fibroblasts and primary human osteoblasts have been cultured on self-assembled monolayers (SAMs) formed by the adsorption of alkanethiols of varying terminal group and alkyl chain length on gold. It has been found that the interactions of both cell types with SAMs are influenced by surprisingly subtle changes in adsorbate structure. Both the nature of the adsorbate terminal group and the length of the alkyl chain have a significant influence on cellular attachment and growth. For both cell types, attachment and growth on the carboxylic acid terminated SAMs was extensive and was accompanied by a high degree of cell spreading. In contrast, attachment and growth on long-chain methyl terminated SAMs were poor. Attachment and growth on short-chain methyl terminated SAMs were intermediate, with reasonable numbers of attached cells being observed and some degree of cell spreading. Sharply contrasting behaviour was observed for the two cell types when cultured on hydroxy terminated SAMs. It was found that fibroblasts attached poorly to these surfaces, while osteoblasts attached and grew nearly as successfully on short-chain hydroxy terminated SAMs as on carboxylic acid terminated SAMs. Osteoblasts attached less well to long-chain hydroxy terminated SAMs, but better than to methyl terminated SAMs.

A SEXAFS investigation of self-assembled monolayers on silver

Abstract Sulfur K-edge surface extended X-ray absorption fine structure (SEXAFS) measurements have been carried out on self-assembled monolayers (SAMs) of alkylthiols adsorbed onto evaporated silver surfaces. By using the Auger yield method, it was found that adequate data could be obtained to allow a preliminary determination of the adsorption site of the S head groups on the predominantly (111) Ag surface. For SAMs of butanethiol and octanethiol, the three-fold hollow site was identified as the most probable position for the S atom. In addition to studies of as-prepared monolayers, the evolution of the NEXAFS spectra of octanethiol SAMs on silver which were progressively photo-oxidised was also investigated. The results supported the model derived for this process from other techniques.