Purpose: The aim was to develop a method to assess the electrostatic properties of human tear samples, and to evaluate their modifications induced by the wear of contact lenses (CLs). Method: The barrier method was developed for the measurement of the isoelectric point (IEP) on relatively small quantities. The method was applied to compare three groups: tears (TNW) of non-wearers, tears (TW_etaf) of regular wearers of etafilcon A CLs, and tears (TW_omaf) of regular wearers of omafilcon A CLs. Zeta potential (ζ) as a function of pH was measured by a Zetasizer Nano ZS90 (Malvern Instruments) on 40%-diluted samples, obtained by mixing 57 μL of tears of different subjects of the same group with 85 μL of HCl aqueous solution. IEP was deduced as the pH at which ζ is zero, i.e. the net electric charge on tear constituents being neutralized. Results: Within an error of about 0.05, IEPs were found to be 2.90 (TNW), 2.80 (TW_omaf), and 3.16 (TW_etaf). On average, a lower H+ concentration is needed to neutralize the surface charge of the tear components of etafilcon A wearers, compared to both TNW and TW_omaf. Conclusion: IEP measurements on tear samples of wearers of different types of CLs are proposed in order to enhance the knowledge on the modifications of the profile of charged species in tears. The TW_etaf results, compared to those of the other groups, are compatible with an increase, due to the wear of etafilcon A CLs, of the relative concentration of high-IEP proteins.

Colciago, S., Picarazzi, S., Lecchi, M., D'Arienzo, M., Tavazzi, S., Zeri, F. (2019). Zeta potential of tear samples: A tool to explore the effects of wear of contact lenses. CONTACT LENS & ANTERIOR EYE, 42(5), 487-491 [10.1016/j.clae.2019.06.003].

Zeta potential of tear samples: A tool to explore the effects of wear of contact lenses

Lecchi, M;D'Arienzo, M;Tavazzi, S;Zeri, F
2019

Abstract

Purpose: The aim was to develop a method to assess the electrostatic properties of human tear samples, and to evaluate their modifications induced by the wear of contact lenses (CLs). Method: The barrier method was developed for the measurement of the isoelectric point (IEP) on relatively small quantities. The method was applied to compare three groups: tears (TNW) of non-wearers, tears (TW_etaf) of regular wearers of etafilcon A CLs, and tears (TW_omaf) of regular wearers of omafilcon A CLs. Zeta potential (ζ) as a function of pH was measured by a Zetasizer Nano ZS90 (Malvern Instruments) on 40%-diluted samples, obtained by mixing 57 μL of tears of different subjects of the same group with 85 μL of HCl aqueous solution. IEP was deduced as the pH at which ζ is zero, i.e. the net electric charge on tear constituents being neutralized. Results: Within an error of about 0.05, IEPs were found to be 2.90 (TNW), 2.80 (TW_omaf), and 3.16 (TW_etaf). On average, a lower H+ concentration is needed to neutralize the surface charge of the tear components of etafilcon A wearers, compared to both TNW and TW_omaf. Conclusion: IEP measurements on tear samples of wearers of different types of CLs are proposed in order to enhance the knowledge on the modifications of the profile of charged species in tears. The TW_etaf results, compared to those of the other groups, are compatible with an increase, due to the wear of etafilcon A CLs, of the relative concentration of high-IEP proteins.
Articolo in rivista - Articolo scientifico
Contact lenses; Isoelectric point; Proteins; Tears; Zeta potential;
English
2019
42
5
487
491
reserved
Colciago, S., Picarazzi, S., Lecchi, M., D'Arienzo, M., Tavazzi, S., Zeri, F. (2019). Zeta potential of tear samples: A tool to explore the effects of wear of contact lenses. CONTACT LENS & ANTERIOR EYE, 42(5), 487-491 [10.1016/j.clae.2019.06.003].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/253976
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