Friction Measurements on Contact Lenses in a Physiologically Relevant Environment: Effect of Testing Conditions on Friction.

Purpose: To characterize the effect of lubricant composition and in vitro ageing on the coefficient of friction (CoF) of a wide range of commercially available soft contact lenses (SCLs).

Methods: The CoF of SCLs was characterized by means of microtribometry against a mucin-coated glass disk. One reusable (RU) silicone-hydrogel (SiHy) lens, senofilcon A, and two daily disposable (DD) lenses, etafilcon A (hydrogel) and nelfilcon A (hydrogel), were tested under different lubricant solutions, including a tear-like fluid (TLF) containing proteins and lipids.

Coefficient of Friction of Human Corneal Tissue.

Purpose: A novel property evaluation methodology was used to determine the elusive value for the human corneal coefficient of friction (CoF).

Methods: Using a microtribometer on 28 fresh human donor corneas with intact epithelia, the CoF was determined in 4 test solutions (≥5 corneas/solution): tear-mimicking solution (TMS) in borate-buffered saline (TMS-PS), TMS in phosphate-buffered saline (TMS-PBS), TMS with HEPES-buffered saline (TMS-HEPES), and tear-like fluid in PBS (TLF-PBS).

Results: Mean (SD) CoF values ranged from 0.

Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses.

Background: Limbal ring (also known as 'circle') contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or 'enclosed' within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of 'circle' contact lenses.

Dip-pen nanolithography of high-melting-temperature molecules.

Direct nanopatterning of a number of high-melting-temperature molecules has been systematically investigated by dip-pen nanolithography (DPN). By tuning DPN experimental conditions, all of the high-melting-temperature molecules transported smoothly from the atomic force microscope (AFM) tip to the surface at room temperature without tip preheating. Water meniscus formation between the tip and substrate is found to play a critical role in patterning high-melting-temperature molecules.

Electrochemical and optical properties of two dimensional electrostatic assembly of Au nanocrystals.

The spectroscopic and electrochemical properties of two-dimensional electrostatic assembly of Au nanocrystals are examined on poly-L-lysine (pLys) modified gold electrodes. The surface preparation for the nanoparticle deposition involved the self-assembly of a monolayer of 11-mercaptoundecanoic acid on the electrode surface, followed by the electrostatic deposition of pLys from aqueous solution. The polyelectrolyte layer acts as the electrostatic anchor for the Au particles.

Photocurrent responses at dye sensitised ultrathin polyelectrolyte multilayers supported on gold electrodes.

The photoelectrochemical behaviour of ionic conducting ultrathin multilayers formed by sequential deposition of poly-L-lysine and poly-L-glutamic acid on modified gold electrodes is investigated upon sensitisation by zinc mesotetrakis(p-sulfonatophenyl)porphyrin.