In this study, we report a new multifunctional nanoparticle with antioxidative and antibacterial activities in vitro. ZnO@GA nanoparticles were fabricated by coordinated covalent bonding of the antioxidant gallic acid (GA) on the surface of ZnO nanoparticles. This addition imparts both antioxidant activity and high affinity for the bacterial cell membrane. Antioxidative activities at various concentrations were evaluated using a 2,2′-azino-bis(ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging method. Antibacterial activities were evaluated against Gram-positive bacteria (Staphylococcus aureus: S. aureus), including several strains of methicillin-resistant S. aureus (MRSA), and Gram-negative bacteria (Escherichia coli). The functionalized ZnO@GA nanoparticles showed good antioxidative activity (69.71%), and the bactericidal activity of these nanoparticles was also increased compared to that of non-functionalized ZnO nanoparticles, with particularly effective inhibition and high selectivity for MRSA strains. The results indicate that multifunctional ZnO nanoparticles conjugated to GA molecules via a simple surface modification process displaying both antioxidant and antibacterial activity, suggesting a possibility to use it as an antibacterial agent for removing MRSA.

Dry eye disease is a multifactorial disorder of the eye and tear film with potential damage to the ocular surface. Various treatment approaches for this disorder aim to alleviate disease symptoms and restore the normal ophthalmic environment. The most widely used dosage form is eye drops of different drugs with 5% bioavailability. The use of contact lenses to deliver drugs increases bioavailability by up to 50%. Cyclosporin A is a hydrophobic drug loaded onto contact lenses to treat dry eye disease with significant improvement. The tear is a source of vital biomarkers for various systemic and ocular disorders. Several biomarkers related to dry eye disease have been identified. Contact lens sensing technology has become sufficiently advanced to detect specific biomarkers and predict disease conditions accurately. This review focuses on dry eye disease treatment with cyclosporin A-loaded contact lenses, contact lens biosensors for ocular biomarkers of dry eye disease, and the possibility of integrating sensors in therapeutic contact lenses.

In this work, antioxidant hydrogels were prepared by the construction of an interpenetrating chitosan network and functionalization with gallic acid. The poly(2-hydroxyethyl methacrylate) p(HEMA)-based hydrogels were first synthesized and subsequently surface-modified with an interpenetrating polymer network (IPN) structure prepared with methacrylamide chitosan via free radical polymerization. The resulting chitosan-IPN hydrogels were surface-functionalized with gallic acid through an amide coupling reaction, which afforded the antioxidant hydrogels. Notably, gallic-acid-modified hydrogels based on a longer chitosan backbone exhibited superior antioxidant activity than their counterpart with a shorter chitosan moiety; this correlated to the amount of gallic acid attached to the chitosan backbone. Moreover, the surface contact angles of the chitosan-modified hydrogels decreased, indicating that surface functionalization of the hydrogels with chitosan-IPN increased the wettability because of the presence of the hydrophilic chitosan network chain. Our study indicates that chitosan-IPN hydrogels may facilitate the development of applications in biomedical devices and ophthalmic materials.

We report a novel zinc oxide (ZnO) nanoparticle with antioxidant properties, prepared by immobilizing the antioxidant 3-(3,4-dihydroxyphenyl)-2-propenoic acid (caffeic acid, CA) on the surfaces of micro-dielectric barrier discharge (DBD) plasma-treated ZnO nanoparticles. The microstructure and physical properties of ZnO@CA nanoparticles were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), infrared spectroscopy, and steady state spectroscopic methods. The antioxidant activity of ZnO@CA nanoparticles was evaluated using an ABTS (3-ethyl-benzothiazoline-6-sulfonic acid) radical cation decolorization assay. ZnO@CA nanoparticles exhibited robust antioxidant activity. Moreover, ZnO@CA nanoparticles showed strong antibacterial activity against Gram-positive bacteria (Staphylococcus aureus) including resistant bacteria such as methicillin-resistant S. aureus and against Gram-negative bacteria (Escherichia coli). Although Gram-negative bacteria appeared to be more resistant to ZnO@CA nanoparticles than Gram-positive bacteria, the antibacterial activity of ZnO@CA nanoparticles was dependent on particle concentration. The antioxidant and antibacterial activity of ZnO@CA may be useful for various biomedical and nanoindustrial applications.