Amine-Rich Organic Thin Films for Cell Culture: Possible Electrostatic Effects in Cell-Surface Interactions

In recent communications from these laboratories, we observed that amine-rich thin organic layers are very efficient surfaces for the adhesion of mammalian cells. We prepare such deposits by plasma polymerization at low pressure, atmospheric pressure, or by vacuum-ultraviolet photo-polymerization. More recently, we have also investigated a commercially available material, Parylene diX AM. In this article we first briefly introduce literature relating to electrostatic interactions between cells, proteins, and charged surfaces. We then present certain selected cell-response results that pertain to applications in orthopedic and cardiovascular medicine: we discuss the influence of surface properties on the observed behaviors of two particular cell lines, human U937 monocytes, and Chinese hamster ovary cells. Particular emphasis is placed on possible electrostatic attractive forces due to positively charged R-NH3+ groups and negatively charged proteins and cells, respectively. Experiments carried out with electrets, polymers with high positive or negative surface potentials are added for comparison

Reduction of X-ray generation in high-intensity laser ion acceleration

In this paper, we report on measurements of bremsstrahlung in laser ion acceleration experiments from ultra-thin, polymer-based target foils. The influence of laser polarization on the generated γ radiation, the maximum achievable proton energy and the total proton number is investigated. A clear benefit in terms of γ radiation reduction by the use of circular polarized light can be observed. At the same time, the total number of accelerated protons was increased

Adhesion of U-937 Monocytes on Different Amine-Functionalised Polymer Surfaces

Human U-937 monocytes are notoriously reluctant to adhere to normally cell-adhering surfaces, for example tissue-culture poly(styrene). In earlier work, these laboratories observed that organic thin films prepared by plasma- or ultraviolet-assisted polymerisation, so-called PVP:N, did facilitate the adhesion and proliferation of U-937 under the condition that the concentration of primary amines exceed a critical value, [NH 2] crit 4.2 at.%. That criterion being satisfied by pristine Parylene diX AM, we have compared its performance with those of particular types of PVP:N, L-PPE:N and UV-PE:N. Here, we report a study of aging of these coating types in atmospheric air, then of time-dependent adhesion of U-937 cells. Although there are similarities, the coatings also manifest interesting differences that so far elude detailed understanding. Human U-937 monocytes do not adhere to normally cell-adhering surfaces, e.g. tissue-culture poly(styrene). We reported that organic thin films did facilitate the adhesion and proliferation of U-937, provided that the concentration of primary amines exceed a critical value, [NH 2] crit 4.2 at.%. That criterion being satisfied by pristine Parylene diX AM, we have compared its performance with L-PPE:N and UV-PE:N, particular types of PVP:N. We report aging of these coating types in atmospheric air, then of time-dependent adhesion of U-937 cells. The coatings manifest interesting differences that so far elude detailed understanding

Oligonucleotide and Parylene Surface Coating of Polystyrene and ePTFE for Improved Endothelial Cell Attachment and Hemocompatibility

In vivo self-endothelialization by endothelial cell adhesion on cardiovascular implants is highly desirable. DNA-oligonucleotides are an intriguing coating material with nonimmunogenic characteristics and the feasibility of easy and rapid chemical fabrication. The objective of this study was the creation of cell adhesive DNA-oligonucleotide coatings on vascular implant surfaces. DNA-oligonucleotides immobilized by adsorption on parylene (poly(monoaminomethyl-para-xylene)) coated polystyrene and ePTFE were resistant to high shear stress (9.5 N/m2) and human blood serum for up to 96 h. Adhesion of murine endothelial progenitor cells, HUVECs and endothelial cells from human adult saphenous veins as well as viability over a period of 14 days of HUVECs on oligonucleotide coated samples under dynamic culture conditions was significantly enhanced (P<0.05). Oligonucleotide-coated surfaces revealed low thrombogenicity and excellent hemocompatibility after incubation with human blood. These properties suggest the suitability of immobilization of DNA-oligonucleotides for biofunctionalization of blood vessel substitutes for improved in vivo endothelialization