Stretching Collagen: Using Fluorophores in Collagen Mimetic Peptides as a Proposed Enantiomeric Sorting Technique

Abstract

Approximately half of all therapeutic drugs sold on the market today are chiral. Chirality is the feature of a molecule whose mirror image is not superimposable. These pairs of molecules are known as enantiomers, and for medications, one enantiomer is typically biologically active for a specific function (eutomer), while the other (distomer) is not. A problem presents itself when the distomer is biologically active in another part of the body, which could cause significant harm. There are several methods currently in use to either separate enantiomers or perform stereoselective reactions that produce the desired enantiomer. However, none of these methods are universal, and some of them can be quite costly. Collagen mimetic peptides are naturally chiral and can exhibit reversible trimerization, making them attractive platforms for development of adjunct therapies. This research aims to create two fluorescent naphthalimide isomers to be embedded within collagen mimetic peptides. These isomers are designed to act as walls of a ‘capsule’ that could potentially trap drug molecules, while reporting that they have done so via changes in their emission behavior. Two collagen mimetic peptide systems were created based on the two naphthalimide isomers. One system, at a relatively high concentration, can fold in a first-order manner. When putative guest compounds are introduced, the fluorescence intensity differs significantly after heating the system and allowing it cool, during which time encapsulation is presumed to be occurring. These results indicate that the peptides react to the presence of the model drugs, though they may not be able to differentiate between enantiomers. Additional studies are warranted to study the effects of other guests on the fluorescent output of the system.