Extraction Efficiency of an Extraction Buffer Used to Quantify Lysozyme Deposition on Conventional and Silicone Hydrogel Contact Lens Materials

Abstract

TFA/ACN is extremely efficient at extracting lysozyme deposited on etafilcon lenses. However, it does not extract all the lysozyme deposited on silicone hydrogel lenses, and alternative extraction procedures should be sought.

Efficacy of an Extraction Solvent Used to Quantify Albumin Deposition on Hydrogel Contact Lens Materials

“…Free iodide was removed from the radiolabeled albumin by extensive dialysis against PBS, and the percentage of free iodide was determined based on the precipitation of protein with trichloroacetic acid and the radioactivity of the supernatant (as described previously). 47,56 In all cases, the samples that had free iodide of less than 1% were used in the study. 125 I-labeled albumin was added to unlabeled solution such that the samples had a counting rate of 10 6 disintegrations per minute/mL (DPM/mL).…”

“…56 Following this, the lenses were carefully removed from the vials and were placed in the sterile, 5 mL (12 ϫ 75 mm), nonpyrogenic, polypropylene round-bottom tubes, and radioactive counts were determined again on the lenses using a Gamma Counter. This count gave the total quantity of labeled albumin that remained on the lenses following its extraction (Lens DPM).…”

“…A comparison of the concentration of various ATPS components from previous in vitro doping experiments, for comparative purposes, is described elsewhere. 56 The simple albumin doping solution was prepared at a concentration of 0.2 mg/mL, using phosphate-buffered saline (PBS) at a pH 7.4. Albumin was labeled with 125 I using the iodine mono-chloride (ICl) method, as described in previous studies.…”

“…32,45,46,48,[53][54][55] Our group has recently reported on the efficacy of this technique for extracting lysozyme from SH and FDA group IV contact lens materials. 56 However, the efficacy of this technique in extracting other major tear proteins (including albumin) from SH and CH contact lens materials has not been reported. Thus, the purpose of this study was to quantify the percentage of albumin extracted by TFA/ACN from SH and etafilcon lens materials, by artificially incubating lenses in 125 I-labeled albumin.…”

A Solid-Phase Assay for the Quantitation of Total Protein Eluted from Balafilcon, Lotrafilcon, and Etafilcon Contact Lenses

“…18,[24][25][26][27] Our laboratory has determined that the mixture 50:50 acetonitrile: 0.2% trifluoroacetic acid, which was found to quantitatively elute proteins from etafilcon lenses, extracts 66% of in vitro loaded lysozyme from lotrafilcon lenses and 57% from balafilcon lenses. 28 Chemical treatment of contact lens materials for protein elution includes the possibility of co-extracting polymeric components, which might subsequently interfere with the assay of total protein. Potential interference from lens cross-reactivity becomes more important with lens materials absorbing very low amounts of protein, particularly the lotrafilcon lens material.…”