Tannic Acid-Modified Silver Nanoparticles in Conjunction with Contact Lens Solutions Are Useful for Progress against the Adhesion of Acanthamoeba spp. to Contact Lenses

Abstract

Acanthamoeba spp. are amphizoic amoebae that are widely distributed in the environment and capable of entering the human body. They can cause pathogenic effects in different tissues and organs, including Acanthamoeba keratitis (AK), which may result in a loss of visual acuity and blindness. The diagnostics, treatment, and prevention of AK are still challenging. More than 90% of AK cases are related to the irresponsible wearing of contact lenses. However, even proper lens care does not sufficiently protect against this eye disease, as amoebae have been also found in contact lens solutions and contact lens storage containers. The adhesion of the amoebae to the contact lens surface is the first step in developing this eye infection. To limit the incidence of AK, it is important to enhance the anti-adhesive activity of the most popular contact lens solutions. Currently, silver nanoparticles (AgNPs) are used as modern antimicrobial agents. Their effectiveness against Acanthamoeba spp., especially with the addition of plant metabolites, such as tannic acid, has been confirmed. Here, we present the results of our further studies on the anti-adhesion potential of tannic acid-modified silver nanoparticles (AgTANPs) in combination with selected contact lens solutions against Acanthamoeba spp. on four groups of contact lenses. The obtained results showed an increased anti-adhesion activity of contact lens solutions in conjunction with AgTANPs with a limited cytotoxicity effect compared to contact lens solutions acting alone. This may provide a benefit in improving the prevention of amoebae eye infections. However, there is still a need for further studies on different pathogenic strains of Acanthamoeba in order to assess the adhesion of the cysts to the contact lens surface and to reveal a more comprehensive picture of the activity of AgTANPs and contact lens solutions.

Keywords: Acanthamoeba keratitis; Acanthamoeba spp.; anti-adhesion potential; contact lens solutions; contact lenses; nanoparticles; tannic acid.

Figure 1

Trophozoite adhesion to the contact lens surface after 90-min incubation (×400 magnification): (A) FDA group 1; (B) FDA group 2; (C) FDA group 3; (D) FDA group 4.

Figure 2

Trophozoites adhered to FDA group 3 contact lenses’ surface after 4 h of incubation (×400 magnification): (A) water control; (B) SCA solution control; (C) SCA + 1.25 ppm AgTANPs; (D) SCA + 2.5 ppm AgTANPs; (E) SCA + 5 ppm AgTANPs; (F) SCA + 10 ppm AgTANPs. The AgTANPs dose-dependent adhesion reduction (AR) in trophozoites is visible in the photos (C–F).