Abstract
Purpose: :
The immobilisation of hydrophilic polysaccharide surface coatings has been shown to be very promising for non-fouling applications on substrates. This study reports on the covalent immobilization of hyaluronic acid (HA) on plasma treated surfaces. The plasma used here is an atmospheric dielectric barrier discharge (DBD) reactor. The advantages of using an atmospheric plasma is that it avoids the high engineering costs generally associated with traditional vacuum based plasmas. These HA grafted polymer surfaces are evaluated in terms of cellular and bacterial response as potential candidates for contact lens and intraocular lens applications.
Methods: :
PMMA and PS surfaces were modified at atmospheric pressure using a laboratory scale DBD system. Characterisation of the polymeric film surfaces pre - and post -processing was determined by monitoring static water contact angle, x-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectrometry (ToF-SIMS) and atomic force microscopy (AFM). Lens epithelial cell (LEC) response was determined by cell adhesion (Crystal violet) and viability assays (MTT). Bacterial response was measured by analyzing the number of colony forming units (CFUs) of Staphylococcus aureus on the various treated surfaces.
Results: :
This study has examined a novel route to tether HA onto DBD functionalized surfaces. HA was successfully grafted onto PMMA and PS. The various surface conditions were confirmed using XPS, ToF-SIMS and AFM analysis. Additionally, ToF-SIMS imaging showed the coatings to be homogenous over a 100 µm area. The nature of the morphology of LECs varied depending on the substrate. Cells on the pristine PMMA and PS were partially spread with actin stress fibres dominant along the long axis of the cells and reduced fibres in the interior of the cells. Cells on the DBD-treated surfaces had a well spread morphology with higher cell areas relative to the pristine surfaces. LECs on the HA-modified surfaces were rounded and detaching. These HA-modified surfaces were also capable of reducing the number of adherent bacteria CFUs when compared to the controls.
Conclusions: :
n the present study, HA has been successfully immobilized onto PMMA and PS. HA grafted surfaces were effective in repelling cellular response and decreasing bacterial adhesion.
Keywords: contact lens • intraocular lens • posterior capsular opacification (PCO)