Gradient substrate assembly for quantifying cellular response to biomaterials

Abstract

Using quantitative fluorescence microscopy in conjunction with a method of gradient substrate assembly established in their group, the authors were able to introduce and measure reproducible changes in cellular morphology and cell density by manipulating polymer grafting density. The mechanism behind this change in cellular behavior was explained by a semiempirical, geometric model that describes the effect of the spatial distribution of the polymer on protein attachment. A 10-fold increase in graft density of poly(2-hydroxyethyl methacrylate) [PHEMA] along the surface of a gradient sample, preexposed to bovine fibronectin, caused a change in the size of fibroblasts on the surface (i.e., cell spreading) from (1238 +/- 704) to (377 +/- 216) microm(2). The results were in quantitative agreement with those obtained on three separate gradient samples. Both cellular response and fibronectin adsorption (as measured via ellipsometry) were found to vary sigmoidally with graft density of PHEMA, demonstrating the high degree of correlation between the two phenomena. A simple, rigid-disk model accounting for the surface coverage of PHEMA was able to predict the amount of adsorbed fibronectin with a correlation coefficient of 0.97. Maximal cell adhesion and cell spreading were found to occur at fibronectin surface densities of 50 and 100 ng/cm(2), respectively. The results demonstrate the role of gradient substrate assembly as a method for quantifying the relationship between protein and cellular response to technologically relevant polymeric materials.

Development of peptide-functionalized synthetic hydrogel microarrays for stem cell and tissue engineering applications

“…Here, as a functional indicator, the extent of cell spreading was observed to parallel the shifts in the cell attachment at different peptide concentrations, shown with RGD SG (0.5mM-15mM) in Figure S3. Specifically, less spreading was observed at low peptide concentrations (0.5 and 1mM), consistent with previous literature suggesting the ligand density is able to influence (stem) cell morphology [53, 55, 58]. In this manuscript, we focused on high-density peptides due to the current lack of high affinity ligands for biomaterials development [59–61].…”

Surface-Bound Soft Matter Gradients

“…biotin). 10,24,123,156,149,217,226,[229][230][231][232][233][234][235][236][237][238][239][240] In addition, surface-bound gradients have also been used to investigate systematically platelet adhesion, 241,242 enzyme immobilization, 243 cell adhesion ( Figures 15 and 16), 11,21,31,64,65,[72][73][74]108,117,118,139,140,142,150,235,[244][245][246][247][248][249][250][251][252][253][254][255][256][257][258]…”

Biomimetic strategies for fracture repair: Engineering the cell microenvironment for directed tissue formation

“…The development of polymer array technologies is aimed at the simultaneous screening of several factors or polymer blends, thus downscaling the resources and time needed for the screening process. One such approach involved the development of materials employing varying physical properties or chemical concentrations 68,69 (the emergence of polymer array technologies has been extensively reviewed elsewhere 70 ). Some studies have leveraged recent developments in microfabrication through robotic liquid-dispensing technology to examine various conditions.…”