Photocrosslinkable hyaluronic acid as an internal wetting agent in model conventional and silicone hydrogel contact lenses
ABSTRACT Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal wetting agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications.
SourceAvailable from: Lyndon W JonesInvestigative ophthalmology & visual science 09/2013; 54(11). DOI:10.1167/iovs.13-13215 · 3.66 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Objectives: The ability of hyaluronic acid (HA) to act as a functional additive in model silicone hydrogel contact lenses to alter the uptake and release characteristics of timolol was investigated. Methods: Model contact lenses were prepared using 2 primary formulations: 2-hydroxyethyl methacrylate (HEMA) with 3-methacryloxypropyltris (trimethylsiloxy) silane (TRIS) in a 9:1 (wt:wt) ratio or N,N-dimethylacrylamide (DMA) with TRIS in a 1:1 (wt:wt) ratio. Ethylene glycol dimethacrylate (EGDMA) was used as the cross-linker. Four different model lens compositions were explored: unmodified controls, lenses containing HA, lenses that were molecularly imprinted with timolol maleate, and those that were both imprinted and contained HA. Model lenses were then used in subsequent materials characterization, drug loading, and drug release studies. Results: Hyaluronic acid was shown to have the ability to act as a functional additive in these model contact lenses, significantly increasing the drug loading and release mass. This ability seemed to be independent of molecular imprinting, but its efficacy was related to the concentration of HA contained within model lenses and the concentration of drug loading solution used to facilitate uptake. Timolol release was sustained for a duration of approximately 2 days, and the dose of drug was shown to be controlled by both HA-drug interactions and molecular imprinting within the silicone hydrogels. Conclusions: Hyaluronic acid, although different than typical functional monomers used in molecular imprinting, can be a useful additive to modify the mass of drug release from model silicone hydrogel lenses.Eye & Contact Lens Science & Clinical Practice 09/2014; 40(5):269-276. DOI:10.1097/ICL.0000000000000033 · 1.68 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: In this work peptide-pyrazole based self-assembled nanofibers were utilized as templates for preparation of biocomposites for potential applications as scaffolds for cartilage tissue engineering. To enhance chondrocyte attachment and proliferation as well as to mimic the extracellular matrix of cartilage tissue, we incorporated the peptide sequence HDSQLEALIKFM that has recently been shown to have an affinity toward chondrocytes. We then incorporated collagen, hyaluronate and chondroitin sulfate, all of which are integral components of cartilage. We utilized the layer-by-layer assembly method to design the biocomposites which were found to be highly biocompatible and supported adherence of chondrocytes. The morphologies of the formed composites were confirmed by transmission electron microscopy and scanning electron microscopy while the binding interactions were probed by fourier transform infrared (FTIR) spectroscopy, and contact angle measurements. The results showed an extensive fibrous network was grown and each layer contributed to the composite making it mimic the ECM of cartilage tissue. Due to their stability and ability to allow cell proliferation and attachment, our results suggest that the biocomposites could potentially be used as a scaffolds in cartilage tissue engineering.Political Communication 10/2014; 4(10). DOI:10.1166/jbt.2014.1237 · 1.24 Impact Factor