Hierarchical Assembly of Atomically Precise Metal Clusters as a Luminescent Strain Sensor

Abstract

We demonstrate the formation of a versatile luminescent organo-inorganic layered hybrid material, composed of bovine serum albumin (BSA)-protected Au30 clusters and aminoclay sheets. X-ray diffraction revealed the intercalation of Au30@BSA in the layered superstructure of aminoclay sheets. Coulombic attraction of the clusters and the clay initiates the interaction, and the appropriate size of the clusters allowed them to intercalate within the lamellar aminoclay galleries. Electron microscopy measurements confirmed the hierarchical structure of the material and also showed the cluster-attached clay sheets. Zeta potential measurement and dynamic light scattering probed the gradual formation of the ordered aggregates in solution. The hybrid material could be stretched up to 300% without fracture. The emergence of a new peak in the luminescence spectrum was observed during the course of mechanical stretching. This peak increased in intensity gradually with the degree of elongation or strain of the material. A mechanochromic luminescence response was further demonstrated with a writing experiment on a luminescent mat of the material, made by electrospinning.

Mechanochromic luminescence of a bionanocomposite hydrogel

“…14 c The gel displayed a reversible change of the emission intensity upon deformation to 300% strain by the reorganization of pyrene. 14 c More recently, it was reported that a film consisting of bovine serum albumin (BSA)@Au 30 clusters intercalated in an “aminoclay”, which is a layered silicate with aminopropyl groups exposed on the surface, and poly(vinyl alcohol) (PVA), 15 exhibited a mechanochromic response from red to white upon stretching at 300% strain. The mechanochromism was explained by the structural distortion of the clusters confined within the aminoclay.…”

“…The mechanochromism was explained by the structural distortion of the clusters confined within the aminoclay. 15…”

Molecular Materials through Microdroplets: Synthesis of Protein-Protected Luminescent Clusters of Noble Metals

“…This favors the formation of a Au 30 core inside a BSA molecule. This cluster was previously reported and studied with different techniques. ,, We followed the same ratio of metal ion/protein concentration during electrospray synthesis. As a result, the Au 30 core was formed.…”

Architecturing materials at mesoscale: some current trends

“…Two examples are to be mentioned. (1) By using C 58 fullerenes as perfect mono-sized building blocks, micrometer-thick films have been formed on inert surfaces and subsequently, their mechanical properties have been measured [199]; (2) a nano-inorganic layered hybrid material, composed of bovine serum albumin (BSA)-protected atomically precise Au 30 clusters and aminoclay sheets was synthesized and its luminescence properties were studied and applied in a strain sensor [200]. The availability of well-defined clusters in sufficient quantities opens up opportunities for the design of novel materials structures, as will be described in the following paragraphs.…”