Enzyme Induced Stiffening of Nanoparticle鈥揌ydrogel Composites with Structural Color

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• 作者：Omar B. Ayyub ; Peter Kofinas
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：9
• 期：8
• 页码：8004-8011
• 全文大小：626K
• ISSN：1936-086X

文摘

The passive monitoring of biological environments by soft materials has a variety of nanobiotechnology applications; however, invoking distinct transitions in geometric, mechanical or optical properties remains a prevalent design challenge. We demonstrate here that close-packed nanoparticle鈥揾ydrogel composites can progress through a substantial shift in such properties by the use of a chemical-to-physical cross-link transition mediated by the catalytic activity of different proteases. Catalytic cleavage of the original hydrogel network structure initiates the self-assembled formation of a secondary, physically cross-linked network, causing a 1200% increase in storage modulus. Furthermore, this unique mechanism can be fabricated as a 3D photonic crystal with broad (鈭?40 nm), visible responses to the targeted enzymes. Moreover, the material provided threshold responses, requiring a certain extent of proteolytic activity before the transition occurred. This allowed for the fabrication of Boolean logic gates (OR and AND), which responded to a specific assortment of proteases. Ultimately, this mechanism enables the design of stimuli-responsive hydrogels, which can proceed through a secondary network formation, after an energetic barrier has been breached. Protease responsive hydrogel nanocomposites, described here, could offer avenues in degradation-stiffening and collapsing materials for a variety of biomaterial applications.