Evaluation of laser spallation as a technique for measurement of cell adhesion strength

Abstract

Cell adhesion to material surfaces is one of the fundamental phenomena of cellular response to implanted devices. Controlling the strength, dynamics, and mechanics of cell adhesion offer opportunities for designing novel biomaterials for tissue engineering and biotechnology. Many techniques have been developed for the purpose of quantifying various types of cell-biomaterial interaction. One method to evaluate cell affinity for a biomaterial is to measure the stress required to remove adherent cells from the material. This study investigates the possibility of using laser spallation, a technique previously developed for measuring the tensile strength of thin film interfaces, for evaluation of initial cell attachment strength. MC3T3-E1 preosteoblasts were cultured on fibronectin-coated polystyrene, a surface known to engage cells in receptor mediated adhesion, and untreated polystyrene, which elicit nonspecific adhesion mechanisms during early stages of cell attachment. The laser spallation technique effectively detached cells from polymer substrates and also distinguished relative cell adhesion strengths to surfaces with known differences in cell binding affinities. Scanning electron micrographs determined that cell detachment resulting from laser spallation left a cleaner surface than jet impingement, possibly suggesting a more complete detachment mechanism. Absolute values of adhesion strengths determined by laser spallation were significantly higher than those found using jet impingement, a previously reported hydrodynamic technique.

Measurement of the tensile strength of cell–biomaterial interface using the laser spallation technique

“…Our experiments provide only an overall strength number, without quantifying the relative contributions of cell surface area, receptor number and receptor binding affinity. Previously [13], high-resolution SEM of polystyrene surfaces from which MC3T3 cells were detached showed the presence of cell debris, suggesting that although most of the debonding occurred at the interface between the substrate and cell membrane and receptor, other types of cohesive failure were also produced. Further analysis of the cell debris revealed positive staining against phospholipid membrane dye and integrin antibodies, suggesting that not all of the detachment was simple de-adhesion.…”

“…An alternative measure would be the stress required to detach 50% of cells, deduced from a curve ranging from the threshold to complete detachment in the stress-waveloaded area. This strategy was adopted in our previous research [13]. The relative merits of these detachment criteria should depend upon the specific application for which the cell adhesion data is sought.…”

“…In this study, a laser spallation technique that was previously modified [13] to measure the attachment strength of MC3T3-E1 preosteoblasts on various types of polystyrene surfaces was used to measure adhesion of additional cell types (osteoblast, chondrocyte and fibroblast) and substrates (untreated and fibronectin-coated polystyrene and titanium substrates). The effect of culturing the cells in serum and serum-free conditions on resulting cell adhesion strength was also investigated.…”

Determination of adhesion strength of pre-bond contaminated composite-to-metal bonded joints by centrifuge tests

“…The principle of centrifuge force has been used for many years as the main mechanical separation process for solids from liquids or for liquids from liquids [9,10] in various applications, e.g. food industry [11], bioengineering [12], ice removal on ground and air transportation industry [13], etc. The centrifuge test is a multi-sample, single-lap fast test.…”

Analysis of flexible substrates for clinical translation of laser-generated shockwave therapy

“…It is also postulated that if the physical length of the shockwaves are on the same scale as the bacterial cells themselves, the same physical stresses occur against their plasma membranes, potentially leading to cellular death, but that analysis is outside the scope of this study. Development of optimized LGS generation has been conducted using soda-lime glass or fused silica glass as the carrier substrate [15,16]. However, the rigid structure of glass is not compatible with clinical translation.…”