Weak Gelation of Hydrophobic Guar by Albumin in Simulated Human Tear Solutions

This initial study shows that hydrophobic modification of guar polymers used in eye drops forms weak gels with human serum albumin (HSA), suggesting that modified guar may offer advantages for treatment of dry eye diseases that lead to elevated HSA concentrations in tears. Specifically, hydroxypropyl guar samples were oxidized and derivatized with linear alkyl amines to give a series of modified guar polymers (MGuar) bearing hydroxypropyl, N-alkylamide, and carboxyl moieties. MGuar interactions with lysozyme and HSA were measured by binding and rheological methods as functions of the alkyl chain length and the extent of hydrophobic modification. HSA binds MGuar, giving weak gels, whereas lysozyme shows little tendency to bind MGuar or to interfere with HSA binding. Six mole percent substitution of decyl hydrophobes gave the strongest gels in the presence of HSA.