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Dong H.,Carnegie Mellon University | Huang J.,CIBA Vision Corporation | Koepsel R.R.,McGowan Institute for Regenerative Medicine | Ye P.,Carnegie Mellon University | And 2 more authors.
Biomacromolecules | Year: 2011

Highly efficient recyclable antibacterial magnetite nanoparticles consisting of a magnetic Fe3O4 core with an antibacterial poly(quaternary ammonium) (PQA) coating were prepared in an efficient four-step process. The synthetic pathway included: (1) preparation of Fe3O 4 nanoparticles via coprecipitation of Fe2+/Fe 3+ in the presence of an alkaline solution; (2) attachment of an ATRP initiating functionality to the surface of the nanoparticles; (3) surface-initiated atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA); and (4) transformation of PDMAEMA brushes to PQA via quaternization with ethyl bromide. The success of the surface functionalization was confirmed by FT-IR, thermal gravimetric analysis (TGA), elemental analysis, and transmission electron microscopy (TEM). The PQA-modified magnetite nanoparticles were dispersed in water and exhibited a response to an external magnetic field, making the nanoparticles easy to remove from water after antibacterial tests. The PQA-modified magnetite nanoparticles retained 100% biocidal efficiency against E. coli (105 to 106E. coli/mg nanoparticles) during eight exposure/collect/recycle procedures without washing with any solvents or water. © 2011 American Chemical Society. Source

Sankaridurg P.,Brien Holden Vision Institute | Sankaridurg P.,Vision Cooperative Research Center | Sankaridurg P.,University of New South Wales | Holden B.,Brien Holden Vision Institute | And 18 more authors.
Investigative Ophthalmology and Visual Science | Year: 2011

Purpose. To determine whether a novel optical treatment using contact lenses to reduce relative peripheral hyperopia can slow the rate of progress of myopia. Methods. Chinese children, aged 7 to 14 years, with baseline myopia from sphere -0.75 to -3.50 D and cylinder ≤1.00 D, were fitted with novel contact lenses (n = 45) and followed up for 12 months, and their progress was compared with that of a group (n = 40) matched for age, sex, refractive error, axial length, and parental myopia wearing normal, single-vision, spherocylindrical spectacles. Results. On adjusting for parental myopia, sex, age, baseline spherical equivalent (SphE) values, and compliance, the estimated progression in SphE at 12 months was 34% less, at -0.57 D, with the novel contact lenses (95% confidence interval [CI], -0.45 -0.69 D) than at -0.86 D, with spectacle lenses (95% CI, -0.74 to -0.99 D). For an average baseline age of 11.2 years, baseline SphE of -2.10 D, a baseline axial length of 24.6 mm, and 320 days of compliant lens wear, the estimated increase in axial length (AL) was 33% less at 0.27 mm (95% CI, 0.22-0.32 mm) than at 0.40 mm (95% CI, 0.35-0.45 mm) for the contact lens and spectacle lens groups, respectively. Conclusions. The 12-month data support the hypothesis that reducing peripheral hyperopia can alter central refractive development and reduce the rate of progress of myopia. © 2011 The Association for Research in Vision and Ophthalmology, Inc. Source

Baio J.E.,University of Washington | Weidner T.,University of Washington | Samuel N.T.,University of Washington | Samuel N.T.,CIBA Vision Corporation | And 4 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2010

The ability to orient biologically active proteins on surfaces is a major challenge in the design, construction, and successful deployment of many medical technologies. As methods to orient biomolecules are developed, it is also essential to develop techniques that can accurately determine the orientation and structure of these materials. In this study, two model protein and peptide systems are presented to highlight the strengths of three surface analysis techniques for characterizing protein films: time-of-flight secondary-ion mass spectrometry (ToF-SIMS), sum-frequency generation (SFG) vibrational spectroscopy, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy. First, the orientation of Protein G B1, a rigid 6 kDa domain covalently attached to a maleimide-functionalized self-assembled monolayer, was examined using ToF-SIMS. Although the thickness of the Protein G layer was similar to the ToF-SIMS sampling depth, orientation of Protein G was successfully determined by analyzing the C2H5S+ intensity, a secondary-ion derived from a methionine residue located at one end of the protein. Next, the secondary structure of a 13-mer leucine-lysine peptide (LK 310) adsorbed onto hydrophilic quartz and hydrophobic fluorocarbon surfaces was examined. SFG spectra indicated that the peptide's lysine side chains were ordered on the quartz surface, while the peptide's leucine side chains were ordered on the fluorocarbon surface. NEXAFS results provided complementary information about the structure of the LK 310 film and the orientations of amide bonds within the LK 310 peptide. © 2010 American Vacuum Society. Source

Weidner T.,University of Washington | Samuel N.T.,University of Washington | Samuel N.T.,CIBA Vision Corporation | McCrea K.,Polymer Technology Group Inc. | And 3 more authors.
Biointerphases | Year: 2010

The structure, orientation, and formation of amphiphilic α-helix model peptide films on fluorocarbon surfaces has been monitored with sum frequency generation SFG vibrational spectroscopy, near-edge x-ray absorption fine structure NEXAFS spectroscopy, and x-ray photoelectron spectroscopy XPS. The -helix peptide is a 14-mer of hydrophilic lysine and hydrophobic leucine residues with a hydrophobic periodicity of 3.5. This periodicity yields a rigid amphiphilic peptide with leucine and lysine side chains located on opposite sides. XPS composition analysis confirms the formation of a peptide film that covers about 75% of the surface. NEXAFS data are consistent with chemically intact adsorption of the peptides. A weak linear dichroism of the amide φ is likely due to the broad distribution of amide bond orientations inherent to the -helical secondary structure. SFG spectra exhibit strong peaks near 2865 and 2935 cm- related to aligned leucine side chains interacting with the hydrophobic surface. Water modes near 3200 and 3400 cm- indicate ordering of water molecules in the adsorbed-peptide fluorocarbon surface interfacial region. Amide I peaks observed near 1655 cm- confirm that the secondary structure is preserved in the adsorbed peptide. A kinetic study of the film formation process using XPS and SFG showed rapid adsorption of the peptides followed by a longer assembly process. Peptide SFG spectra taken at the air-buffer interface showed features related to well-ordered peptide films. Moving samples through the buffer surface led to the transfer of ordered peptide films onto the substrates. © 2010 American Vacuum Society. Source

Ciba Vision Corporation | Date: 2010-06-04

An ophthalmic lens suited for extended-wear periods of at least one day on the eye without a clinically significant amount of corneal swelling and without substantial wearer discomfort. In one embodiment, an opthalmic lens is a copolymerization product of at least one oxyperm, at least one ionoperm, and a crosslinker. In one embodiment, a lens has a tensile modulus of less than about 3.0 MPa, yet in another embodiment, the tensile modulus is between about 0.5 to about 1.5 MPa.

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