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: sciencedirect.com[show abstract] [hide abstract]
ABSTRACT: Biomimetic poly(2-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) brushes with graft density 0.06-0.39 chains/nm2 and chain length 5-200 monomer units were prepared from silicon wafer surfaces by combining self-assembly of initiator and surface-initiated atom transfer radical polymerization (ATRP). Water contact angle, X-ray photoelectron spectroscopy, and atomic force microscopy were used to characterize the modified surfaces. These surfaces with well-controlled poly(MPC) brushes were tested for protein repelling performance. Fibrinogen adsorption from tris-buffered saline at pH 7.4 decreased significantly with increasing graft density and/or chain length of poly(MPC) and reached a level of < 10 ng/cm2 at graft density > or = 0.29 chains/nm2 and chain length > or = 100 units, compared to ca. 570 ng/cm2 for the unmodified samples. While the fibrinogen adsorption was determined by both graft density and chain length, it showed a stronger dependence on graft density than on chain length.Biomaterials 02/2006; 27(6):847-55. · 7.60 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Hyaluronan (HA) is a natural polysaccharide abundant in biological tissues and it can be modified to prepare biomaterials. In this work, HA modified with glycidyl methacrylate was photocrosslinked to form the first network (PHA), and then a series of highly porous PHA/N,N-dimethylacrylamide (DAAm) hydrogels (PHA/DAAm) with high mechanical strength were obtained by incorporating a second network of photocrosslinked DAAm into PHA network. Due to the synergistic effect produced by double network (DN) structure, despite containing 90% of water, the resulting PHA/DAAm hydrogel showed a compressive modulus and a fracture stress over 0.5 MPa and 5.2 MPa, respectively. Compared to the photocrosslinked hyaluronan single network hydrogel, which is generally very brittle and fractures easily, the PHA/DAAm hydrogels are ductile. Mouse dermal fibroblast was used as a model cell line to validate in vitro non-cytotoxicity of the PHA/DAAm hydrogels. Cells deposited extracellular matrix on the surface of these hydrogels and this was confirmed by positive staining of Type I collagen by Sirius Red. The PHA/DAAm hydrogels were also resistant to biodegradation and largely retained their excellent mechanical properties even after 2 months of co-culturing with fibroblasts.Biomaterials 06/2008; 29(14):2153-63. · 7.60 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: A novel hyaluronic acid-poly(ethylene glycol)-poly(lactide-co-glycolide) (HA-PEG-PLGA) copolymer was synthesized and characterized by infrared and nuclear magnetic resonance spectroscopy. The nanoparticles of doxorubicin (DOX)-loaded HA-PEG-PLGA were prepared and compared with monomethoxy(polyethylene glycol) (MPEG)-PLGA nanoparticles. Nanoparticles were prepared using drug-to-polymer ratios of 1:1 to 1:3. Drug-to-polymer ratio of 1:1 is considered the optimum formulation on the basis of low particle size and high entrapment efficiency. The optimized nanoparticles were characterized for morphology, particle size measurements, differential scanning calorimetry, x-ray diffractometer measurement, drug content, hemolytic toxicity, subacute toxicity, and in vitro DOX release. The in vitro DOX release study was performed at pH 7.4 using a dialysis membrane. HA-PEG-PLGA nanoparticles were able to sustain the release for up to 15 days. The tissue distribution studies were performed with DOX-loaded HA-PEG-PLGA and MPEG-PLGA nanoparticles after intravenous (IV) injection in Ehrlich ascites tumor-bearing mice. The tissue distribution studies showed a higher concentration of DOX in the tumor as compared with MPEG-PLGA nanoparticles. The in vivo tumor inhibition study was also performed after IV injection of DOX-loaded HA-PEG-PLGA nanoparticles up to 15 days. DOX-loaded HA-PEG-PLGA nanoparticles were able to deliver a higher amount of DOX as compared with MPEG-PLGA nanoparticles. The DOX-loaded HA-PEG-PLGA nanoparticles reduced tumor volume significantly as compared with MPEG-PLGA nanoparticles.Nanomedicine: nanotechnology, biology, and medicine 01/2008; 3(4):246-57. · 6.93 Impact Factor