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Sudeep Kumar Gade, Richard Hoskins, Stephen Rimmer, Prashant Garg, Venkata Vamsi Krishna Venuganti; Corneal penetration of functionalized poly (N-isopropylacrylamide) (PNIPAM) polymers. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5691.
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© ARVO (1962-2015); The Authors (2016-present)
To study corneal penetration, cytotoxicity and cell uptake of PNIPAM polymers synthesized for the delivery of antimicrobial agents.
Functionalized PNIPAM polymers (Nile red tagged) of different chain lengths and moieties were synthesized. The polymers tested for corneal penetration study were a) X13002-601 15:1 b) X13002-401 25:1 c) RH3-66 extended 25:1 polymer. Cytotoxicity of the polymers was tested on human corneal epithelial cells (HCEC) and cell uptake studies were carried out using flow cytometer both at room temperature (26 ± 1 degree Centigrade) and at 37 degree Centigrade. In vitro human corneal permeation studies were performed both passively and using iontophoresis using Franz’s diffusion cells. 1.0 mg/ml polymer concentration was used and the permeation was studied on intact and Staphylococcus aureus infected cornea. The penetration was analyzed using confocal laser scanning microscopy (CLSM).
Viability of HCEC cells after incubation with different PNIPAM polymers at 1-5 mg/ml showed concentration dependent cytotoxicity. Below 5 mg/ml, cells were found to be >98% viable. Flow cytometry data did not show any polymer binding to the cells at 37 degree Centigrade because the LCST of the polymers is >32 degree Centigrade. However, polymer uptake was observed at room temperature suggesting temperature dependent binding and uptake mechanism. Passively, incubation of PNIPAM polymers for 4 hours on uninfected and infected corneas showed mean penetration of ~55 and 80 µm respectively. However, upon application of constant current (0.45 mA/cm2), corneal penetration significantly improved to ~122 and 134 µm respectively for intact and infected corneas. RH3-66 extended 25:1 polymer showed highest corneal penetration of about 150 µm in the infected tissue.
The data suggests that the polymers can be utilized for ocular drug delivery. Further, application of iontophoresis makes absorption into the tissues more efficient.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
CLSM images of intact and S. aureus infected human cornea after incubation with PNIPAM polymers using iontophoresis. a) X13002-601 15:1 b) X13002-401 25:1 c) RH3-66 extended 25:1 polymer.
Quantitative fluorescence intensity analysis of in vitro PNIPAM polymers penetration through human cornea.
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