Delivery of optical contrast agents using Triton-X100, part 2: enhanced mucosal permeation for the detection of cancer biomarkers.

Uniform delivery of optical contrast agents through mucosal tissue has proven a significant challenge. Topical permeation enhancers that have proven useful for skin demonstrate limited success in mucosal tissue. We sought to develop a topical permeation strategy capable of delivering tissue-impermeant molecular-specific contrast agents through mucosal epithelium in a uniform, controlled manner. We demonstrate that Triton-X100 can be utilized to deliver targeted and untargeted optical contrast agents through freshly excised normal mucosal epithelium and epithelial cancer. Macromolecules up to 150 kDa in size were successfully delivered via transcellular and paracellular routes. The depth of Triton-mediated permeation was modulated by varying the treatment time and concentration. Uniform epithelial penetration to a depth of 500 mum was achieved in approximately 1.5 h for molecules of 40 kDa or less. Larger optical probes required longer treatment times. Coadministration of molecular-specific contrast agents with Triton-X100 treatment facilitated simultaneous labeling of biomarkers on the cell membrane, in the cytoplasm, and in the nucleus with high specificity. Together, these data suggest that Triton-X100 is a promising topical permeation enhancer for mucosal delivery of tissue-impermeant molecular-specific optical contrast agents.