title: Molecular interactions of exogenous chemical agents with collagen--implications for tissue optical clearing.
abstract: Reduction of optical scattering in turbid biological tissues using nonreactive chemical agents has potential applications for light-based diagnostics and therapeutics. Optical clearing effects by exogenous chemical agents, in particular sugars and sugar alcohols, have been found to be temporary with tissue rehydration. Applications with dermatologic laser therapies are now being investigated, but suffer from the inability of studied agents to penetrate the superficial layers of human skin. Selection, design, and refinement of topically effective chemical agents are hindered by a lack of fundamental understanding of tissue clearing mechanisms. We present recent work, particularly from the biochemistry community, detailing molecular interactions between chemical agents and collagen. This body of work demonstrates the perturbative effects of sugars and sugar alcohols on collagen high-order structures at micro- and nanometer length scales by screening noncovalent bonding forces. In addition, these studies emphasize the nonreactive nature of agent-collagen interactions and the ability of noncovalent bonding forces to recover with agent removal and drive reassembly of destabilized collagen structures. A mechanism of tissue optical clearing is proposed based on agent destabilization of high-order collagen structures.
authors.affiliation: Texas A&M University, Department of Biomedical Engineering, 337 Zachry Engineering Center, 3120 TAMU, College Station, Texas 77843, USA. ayeh@tamu.edu
authors.forename: Alvin T
authors.initials: AT
authors.lastname: Yeh
authors.forename: Jason
authors.initials: J
authors.lastname: Hirshburg
mesh_terms: D000818:Animals; D001665:Binding Sites; D002241:Carbohydrates / Q000737:chemistry* / Q000493:pharmacokinetics; D002468:Cell Physiological Phenomena; D003094:Collagen / Q000737:chemistry* / Q000378:metabolism; D003238:Connective Tissue / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D019281:Dimerization; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008657:Metabolic Clearance Rate; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D011485:Protein Binding; D012995:Solubility; D013402:Sugar Alcohols / Q000737:chemistry* / Q000493:pharmacokinetics
chemical_list: D002241:Carbohydrates; D013402:Sugar Alcohols; D003094:Collagen