Injectable nanomaterials as matrix precursors

Natural extra cellular matrices (ECMs) are characterized by a complex hyer-archical organization centred at the nano scale. From a simplistic point of view, 

More recently, the issue of in situ forming fibrillar matrices has been tackled with the development of self-assembling synthetic peptides. Two main classes of such peptides can be recognized the first one takes inspiration from the association properties of amyloid protein, with a self-assembly primarily based on the formation of /3-sheets and on hydrophobic association this latter feature is often obtained by alternating ionic and hydrophobic aminoacidic residues, although the presence of hydrophobic end-groups can promote similar effects.  

A second class of peptides takes the elastin (VPGVG) motif as an inspiration to produce thermosensitive j8-spirals, which allows a temperature-triggered formation of fibrillar hydrogels.  

The infinite possibilities that we have to synthesize a peptide sequence provide great versatility in designing the final stmcture and properties of the self-assembled hydrogel. However, unwanted immune responses when these gels are applied in vivo still remain a challenge. 

A typical example is offered by Pluronics, i.e. triblock copolymers of PEG and poly(propylene glycol) (PPG) Pluronic suspensions, above a critical concentration, are typically liquid at room temperature, but undergo a very fast 

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