Comparative 1H-NMR studies on the physical state of water in soft contact lens and mouse lens

Abstract

The physical state of water in mouse lenses (2-, 4- or 8-wk-ohl) and soft contact lenses (SCLs, water content from 18.4 to 79.2%) were studied by measuring spin-lattice relaxation times ( T 1) and apparent intermolecular cross-relaxation times ( T 1S) from irradiated protein or polymer protons to water protons, using 360 MHz 1H-NMR spectrometer at 25°C. (1) 1 T 1 values of SCLs increased gradually with increasingly dry weight ( W(%)). 1 T is values of SCLs were approximately zero at W of 20.8 and 26.8%, increased gradually from 26.8% and then steeply above ∼ 50%. (2) A plot of 1 T 1 vs. W(%) of mouse lenses was almost equal to that of SCLs. However, a plot of 1 T is vs. W(%) was an approximately straight line with the intercept at W of 23% and with the slope which is almost equal to that of SCLs above W of ∼ 50%. The plot of 1 T is vs. W(%) of mouse lenses might indicate the significant change in the physical state of water and/or protein-water interactions above W of 23%.