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Active Modulation of States of Prestress in Self-Assembled Short Peptide Gels
- Cox, Henry, Cao, Meiwen, Xu, Hai, Waigh, Thomas A., Lu, Jian R.
- Biomacromolecules 2019 v.20 no.4 pp. 1719-1730
- artificial intelligence, crosslinking, fluorescence microscopy, hydrogels, models, modulus of elasticity, osmotic pressure, solutes, synthetic peptides, temperature, therapeutics, viscoelasticity, wavelengths
- Peptide hydrogels are excellent candidates for medical therapeutics due to their tuneable viscoelastic properties, however, in vivo they will be subject to various osmotic pressures, temperature changes, and biological co-solutes, which could alter their performance. Peptide hydrogels formed from the synthetic peptide I₃K have a temperature-induced hardening of their shear modulus by a factor of 2. We show that the addition of uncross-linked poly(N-isopropylacrylamide) chains to the peptide gels increases the gels’ temperature sensitivity by 3 orders of magnitude through the control of osmotic swelling and cross-linking. Using machine learning combined with single-molecule fluorescence microscopy, we measured the modulation of states of prestress in the gels on the level of single peptide fibers. A new self-consistent mixture model was developed to simultaneously quantify the energy and the length distributions of the states of prestress. Switching the temperature from 20 to 40 °C causes 6-fold increases in the number of states of prestress. At the higher temperature, many of the fibers experience constrained buckling with characteristic small wavelength oscillations in their curvature.