Martens, P.Ly, M.Adams, D.Penzkover, K.Strudwick, X.Cowin, A.Poole-Warren, L.2017-12-102017-12-102015Journal of Biomaterials Applications, 2015; 30(3):257-2680885-32821530-8022http://hdl.handle.net/2440/109906Gene silencing using small interfering RNA has been proposed as a therapy for cancer, viral infections and other diseases. This study aimed to investigate whether layer-by-layer polymer surface modification could deliver small interfering RNA to decrease fibrotic processes associated with medical device implantation. Anti-green fluorescent protein labelled small interfering RNA was applied to tissue culture plates and polyurethane using a layer-by-layer technique with small interfering RNA and poly-L-lysine. In vitro studies showed that the level of down-regulation of green fluorescent protein was directly related to the number of coatings applied. This layer-by-layer coating technique was then used to generate Rhodamine-Flii small interfering RNA-coated implants for in vivo studies of small interfering RNA delivery via subcutaneous implantation in mice. After two days, Rh-positive cells were observed on the implants' surface indicating cellular uptake of the Rhodamine-Flii small interfering RNA. Decreased Flii gene expression was observed in tissue surrounding the Rhodamine-Flii small interfering RNA coated implants for up to seven days post implantation, returning to baseline by day 21. Genes downstream from Flii, including TGF-β1 and TGF-β3, showed significantly altered expression confirming a functional effect of the Rhodamine-Flii small interfering RNA on gene expression. This research demonstrates proof-of-principle that small interfering RNA can be delivered via layer-by-layer coatings on biomaterials and thereby can alter the fibrotic process.en© The Author(s) 2015Animal model; drug delivery; polyurethane; siRNAJournal article003007750210.1177/08853282155794220003617673000012-s2.0-84942093074267928Cowin, A. [0000-0003-2885-2080]