Block copolymers nanofilms have been shown to mimick key natural biological processes. Scientists from University of California-Los Angeles and Northwestern University have examined the application in nanomedicine of a copolymeric nanomembrane matrix loading anti-inflammatory dexamethasone.

Nanomembranes were prepared by Langmuir-Blodgett deposition of polymethyloxazoline-polydimethylsiloxane-polymethyloxazoline (PMOXA-PDMS-PMOXA) copolymer via interfacial addition to a subphase of water, followed by the interlacing of the polymers with dexamethasone. This copolymer possess amphiphilic properties by being composed of alternating hydrophilic and hydrophobic groups. Dexamethasone integration with the amphiphiles was confirmed by surface pressure isotherms and fluorescence microscopy.

The dexamethasone-copolymer mixture, named PolyDex, was found to inhibit LPS (lipopolysaccharide)-mediated induction of IL-12p40 (interleukine 12 p40 subunit), IL-6 (interleukine 6), TNF-α (tumor necrosis factor alpha), IP-10 (interferon gamma inducible protein 10) and iNOS (inducible nitric oxide synthase). Studies of polymer-based activity upon inflammatory gene expression and DNA fragmentation assays demonstrated that the supression of inflammatory gene expression was due to dexamethasone activity. 

Gene expression analysis also demonstrated that the varying degrees of inflammatory gene supression was dependent on the number of deposition cycles conducted. The Langmuir-Blodgett layer-by-layer deposition technique permits the capability to determine the amount of drug deposited on top of the substrate due to the number of film deposition cycles conducted. 

In order to characterize the in vivo PolyDex activity, uncoated and PolyDex-coated polyethylene disks were implanted in mice. Following punch biopsies with tissue imagery via hematoxylin/eosin and macrophage specific staining, PolyDex coating was found to prevent accumulation of infiltrating immune cells to disk implantation site.

According to the authors, this study shows that composite nanofilms provide an excellent platform for adjustable targeted drug delivery systems.

Source: Chow EKH, Pierstorff E, Cheng G, Ho D. ACS Nano 2(1) (2008) 33-40