Photoresponsive retinal-modified silk-elastin copolymer.

Journal of the American Chemical Society (2013-02-07)
Zhongyuan Sun, Guokui Qin, Xiaoxia Xia, Mark Cronin-Golomb, Fiorenzo G Omenetto, David L Kaplan
ABSTRACT

The chimeric proteins, silk-elastin-like protein polymers (SELPs), consist of repeating units of silk and elastin to retain the mechanical strength of silk, while incorporating the dynamic environmental sensitivity of elastin. A retinal-modified SELP was prepared, modified, and studied for photodynamic responses. The protein was designed, cloned, expressed, and purified with lysine present in the elastin repeats. The purified protein was then chemically modified with the biocompatible moiety retinal via the lysine side chains. Structural changes with the polymer were assessed before and after retinal modification using Fourier transform infrared spectroscopy and circular dichroism spectroscopy. Optical studies and spectral analysis were performed before and after retinal modification. The random-coil fraction of the protein increased after retinal modification while the β-sheet fraction significantly decreased. Birefringence of the modified protein was induced when irradiated with a linearly polarized 488 nm laser light. Retinal modification of this protein offers a useful strategy for potential use in biosensors, controlled drug delivery, and other areas of biomedical engineering.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Elastin from bovine neck ligament, powder
Sigma-Aldrich
Elastin, soluble from bovine neck ligament, salt-free, lyophilized powder
Sigma-Aldrich
Elastin from human skin, insoluble powder
Sigma-Aldrich
Elastin, soluble from human aorta, lyophilized powder
Sigma-Aldrich
Elastin from mouse lung, powder
Sigma-Aldrich
Elastin, soluble from human lung, lyophilized powder