Inhibition of lens epithelial cell growth via immobilisation of hyaluronic acid on atmospheric pressure plasma modified polystyrene

Abstract

Naturally occurring macromolecules have the potential for providing non-fouling coatings on substrates based on a steric entropic principle. In order for this effect to occur, the macromolecules that adhered to the surface must have the correct chemical conformation. This article reports on the immobilisation of hyaluronic acid (HA) onto polystyrene substrates for the purpose of repelling cellular adhesion thereon. In order to create a polystyrene surface capable of adhering HA in the required orientation substrates were treated by atmospheric pressure plasma processing in air. The resulting oxidised surfaces were then aminated by the chemisorption of the 3-aminopropyltrimethoxysilane (APTMS) linker molecule. Three distinct chemical states were found for the APTMS amine group: a neutral, a protonated and a hydrogen bonded state, as determined by X-ray photoelectron spectroscopy (XPS). Carbodiimide coupling of HA at two different macromolecular concentrations (1 mg cm À3 and 3 mg cm À3) to the aminated surfaces on oxidized polystyrene resulted in covalent immobilisation of the polysaccharide. The chemistry and topography of the polymer surface at each stage of the coating process were analysed by a combination of XPS, ToF-SIMS, and AFM. XPS demonstrates that HA was successfully grafted to the aminated PS surfaces. The degree of chemical homogeneity on the surfaces was determined by ToF-SIMS. Changes in topography resulting from the immobilization process were evident in the AFM images. In vitro studies of the response of human lens epithelial cells (LEC) to the HA-modified polystyrene indicated a significant reduction in cell numbers at all time points post-seeding compared to the control. These results coupled with the surface analysis data indicate that the immobilization method based on atmospheric plasma activation of the polymer surface creates a HA layer with a steric conformation capable of inhibiting cellular attachment.

Competitive protein adsorption on polysaccharide and hyaluronate modified surfaces

“…For our hyaluronized silicon surfaces made at the NaHA concentration of 1.2 mg ml −1 , XPS used under the same conditions as for dextran showed the ratio of C to N on average to be 10.8 (streptococcus zooepidemicus NaHA), 11.2 (human NaHA), and 11.4 (rooster comb NaHA). These values are all consistent with XPS results for HA films determined in chemisorptions experiments (D'Sa et al 2011; Suh et al 2005). Given that the ellipsometric data presented in Figure 2 indicate the HA films to be much thicker than the 2.5 nm detection depth used, it is unlikely that these measurements include interference from other chemical constituents present.…”

“…Park et al (Park et al 2003) found that fibroblasts did not spread on HA-containing gel surfaces. Polystyrene surfaces modified via immobilization of hyaluronic acid have been shown to resist attachment of human lens epithelial cells for application in ocular medicine (D'Sa et al 2011). Patterned surfaces of dextran and HA show preferential attachment of macrophages to the dextranized regions (Tsai et al 2011b).…”

Bottom-up fabrication of zwitterionic polymer brushes on intraocular lens for improved biocompatibility

“…For example, treating IOL surface with plasma or immobilizing with heparin, poly(ethylene glycol), or phosphorylcholine can reduce the bioadhesion better than coating with inert materials. [11][12][13][14][15][16] However, bioadhesion can still be found on coated hydrophilic surfaces, which may be due to the undesired surface coating by common hydrophilic molecules. A more effective antifouling coating is essential for IOL surface modifications.…”

Biomaterials for ocular reconstruction

“…Several groups have studied the effects of changing surface chemistry with the addition of various functional groups such as amine, carboxyl and hydroxyl groups, to encourage cell attachment in various cell types [78][79][80]. The cellular response could also be controlled by incorporating ECM molecules such as glycosaminoglycan [70,81,82].…”

“…One method that has been investigated to alleviate PCO is surface modification of IOLs to control the cellular response [57, [70][71][72][73]. It is widely known that material properties such as the surface chemistry, wettability and roughness can affect the cellular response [74][75][76][77].…”