Biomimetic Elastin-Like Polypeptides as Materials for the Activation of Mechanophoric Catalysts

Abstract

Elastin-like polypeptides (ELPs) are well known for their elastic and thermoresponsive behaviors. Their elasticity originates from the formation of a β-spiral which is the consequence of stacking type-II β-turns, formed from individual VPGVG pentapeptide units. Here, the synthesis of ELPs of varying chain lengths [VPGVG, (VPGVG) 2 , and (VPGVG) 4 ] and their coupling to a mechanoresponsive catalyst are reported. The attached ELP chains can act as "molecular springs," allowing for an efficient uptake and transmission of an applied force to the mechanophoric bond. This leads to stress-induced activation of the mechanophoric catalyst, in turn transforming mechanical energy into a "click" reaction. Secondary structure analysis via IR and CD spectroscopy revealed that the β-spiral formation of the ELP is not affected by the coupling process and the β-spiral is still intact in the mechanocatalyst after the coupling. Mechanochemical activation of the synthesized catalysts by an external applied force, studied via ultrasonication, showed conversions of the copper(I)-catalyzed alkyne-azide "click" reaction (CuAAC) up to 5.6% with an increasing chain length of the peptide, proving the potential to incorporate this chemistry into biomaterial engineering.

Mechanochemical Release of Non‐Covalently Bound Guests from a Polymer‐Decorated Supramolecular Cage

“…Concomitantly, the mechanochemical activation of various metal−ligand bonds (metallocenes; [8] Zn, Cu, Ni, and Rh complexes; [9a,b] N‐heterocyclic carbene complexes with Ag, Ru, [9c–i] and Cu; [9j–m] as well as Pd phosphanes [9n] ) was successfully carried out. In addition, force activation of supramolecular rotaxanes bearing poly(methyl acrylate) (PMA) backbones was achieved by bond scission at the rotaxane junction, [10a,c,d] while on the other hand, catenanes are able to effectively distribute tensile deformation in macrocycles and can thus be considered a mechanical protecting group [10b] …”

Mechanochemische Freisetzung nichtkovalent gebundener Gäste aus einem mit Polymerketten dekorierten supramolekularen Käfig

“…Zudem wurde über eine Vielzahl von responsiven Systemen berichtet, welche Licht [7a–c] oder chemische Stimuli als Trigger verwenden [7d,e] . Zusätzlich wurde die mechanochemische Aktivierung verschiedener Metall‐Liganden‐Bindungen – d. h. Metallocene, [8] Zn‐, Cu‐, Ni‐ und Rh‐Komplexe, [9a,b] N‐heterocyclische Carbenkomplexe mit Ag, Ru [9c–i] und Cu [9j–m] sowie Pd‐Phosphane [9n] – durchgeführt. Darüber hinaus wurde die kraftinduzierte Aktivierung von supramolekularen Rotaxanen mit Poly(methylacrylat) (PMA)‐Rückgrat durch Bindungsspaltung an der Rotaxan‐Verbindungstelle erzielt [10a,c,d] .…”

Reversible regulation of metallo-base-pair interactions for DNA dehybridization by ultrasound

“…Tailoring the force-sensitivity of a mechanophore can be achieved by relying on supramolecular interactions, among which the polymer mechanochemical activation of various metal-ligand bonds is well-investigated. For example, Pd and Pt pincer complexes, 13 Pd coordination cages; 10 metallocenes; [14][15][16] Zn, Cu, Ni, Rh, and Ru acetylacetonates; 17,18 Nheterocyclic carbene complexes with Ag, Ru, [19][20][21][22][23] and Cu; [24][25][26][27] as well as Pd phosphanes 28 were successfully activated by force. However, all of the above examples use synthetic polymers and mechanophores, while the use of biomacromolecular units remains unexplored in this context.…”