Oligomeric Hydrogels Self‐Assembled from Reduction‐Controlled Condensation

Abstract

AbstractPolymer hydrogels and small‐molecule‐based (SMB) supramolecular hydrogels have been widely explored. But oligomeric hydrogels have remained a challenge because synthetic difficulties of the oligomers and control of their amphiphilicities. Reported herein is the rational design of two precursors Cys(SEt)‐Lys‐CBT (1) and (Cys‐Lys‐CBT)2 (2) (CBT=2‐cyano‐6‐aminobenzothiazole) and the use of a biocompatible condensation to prepare oligomeric hydrogels. Glutathione reduction of 1 or 2 yields the same gelator Cys‐Lys‐CBT (3) which condenses with each other to yield amphiphilic cyclic oligomers. The oligomers instantly self‐assemble into nanofibers and form oligomeric hydrogels with similar mechanic properties. Chemical analyses indicated that the major condensation product in both two hydrogels is a cyclic dimer. Considering its biocompatibility, optimal mechanical strength, and biodegradability, we believe that our oligomeric hydrogel might be useful for long‐term drug delivery in the future.