Platelet adhesion onto chargeable functional group gradient surfaces

Abstract

Functional group gradients were prepared on low-density polyethylene (PE) sheets. The surface density of grafted functional groups was gradually changed along the sample length by way of corona discharge treatment with gradually increasing power following graft copolymerization of acrylic acid (AA), sodium p-styrene sulfonate (NaSS), or N,N-dimethyl aminopropyl acrylamide (DMAPAA). AA and NaSS are negatively chargeable and DMAPAA is positively chargeable in phosphate-buffered saline or plasma solution at pH 7.3-7.4. The prepared functional group gradient surfaces were characterized by measurement of the water contact angle, by electron spectroscopy for chemical analysis, and by Fourier transform infrared spectroscopy in the attenuated total reflectance mode. All these measurements indicated that the functional groups were grafted onto the PE surfaces with gradually increasing density. The platelets adhered to the functional group gradient surfaces along the sample length were counted and observed by scanning electron microscopy. It was observed that the platelet adhesion to the gradient surfaces decreased gradually with the increasing surface density of functional groups. This may be related to the hydrophilicity of the surfaces. The DMAPAA-grafted surface showed a large amount of platelet adhesion, probably due to its positive charge character, while the AA-grafted surface, which is charged negatively, showed poor platelet adhesion. However, the NaSS-grafted surface, which is also charged negatively, showed a relatively large amount of platelet adhesion. This may be associated with the existence of an aromatic ring close to the ionizable group in NaSS. It seems that surface functional groups and their charge character, as well as wettability, play important roles for platelet adhesion.

Species and Density of Implant Surface Chemistry Affect the Extent of Foreign Body Reactions

“…This observation can be correlated with previous studies which have linked the negatively charged surface functionality inhibiting the migration of negatively charged cells towards the functionalized surface. 43,68,[78][79][80] Rather unexpectedly, we find that the density of surface functionality has little or no influence on tissuereactions to microsphere implants. These results contradict many in vitro observations which found cell adhesion to be directly correlated to the density of functionalization.…”

“…11,[18][19][20]23,57,58,60 Surface chemical properties of implant materials have been shown to affect protein adsorption and acute cellular responses. 33,34,42,[61][62][63][64][65][66][67][68][69] In the present study, we examined the hypothesis that biomaterial-mediated fibrotic reactions could be substantially reduced by altering both the type and/ordensity of surface functionality…”

Influence of substratum surface chemistry/energy and topography on the human fetal osteoblastic cell line hFOB 1.19: Phenotypic and genotypic responses observed in vitro☆

“…Adherent cells then slowly (typically within hours) spread over the surface, depending on compatibility with the surface, expressing a strong 'biological component of adhesion' [38] that includes secretion of extracellular matrix (ECM) and results in the flattening of cells on the substratum [2] (spreadcell length is about 3-10 times height [9]). Needless to say, (protein) composition of the fluid phase can greatly affect the entire cell adhesion process [31,33,[55][56][57][58][59]. Thus, it is apparent that the short-term (<3 days) cell adhesion/proliferation process spans a broad range of time and length scales.…”

Mechanical and Biological Properties of Bio-Inspired Nano-Fibrous Elastic Materials from Collagen

“…Polanowska-Grabowska and coworkers reported that the platelet adhesion rate on a gelatin-coated surface was lower than on collagen-coated or fibrinogen-coated surfaces [48]. However, blood coagulation is known to depend on material properties, such as surface-free energy, surface charge, and wettability; these properties govern protein adsorption involving platelet adhesion [49,50]. Experiments using human whole blood are needed to test the clinical applications of the gels.…”