A functional immobilization of semiconductor nanoparticles (quantum dots) on nanoporous aluminium oxide

Abstract

6421 28 26652 Semiconductor nanoparticles (so-called 'quantum dots ', QDs) are investigated for about 20 years because of their unique fluorescent and semiconductive properties. QDs were mainly used for analytical systems outside and inside a living organism. However, for most of these analytical systems, surface of QDs has to be modified. Immobilization techniques for semiconductor nanoparticles are showing wide interests within solar-cell technologies and biosensor development. A functional inorganic/organic hybrid nanosystem could be realized by combination of an inorganic synthesis of semiconductor nanoparticles with commonly used amino acid chemistry on the surface of extremely hydrophilic aluminium oxide filter membranes. 3-Aminopropyle-triethoxysilane (APTES), allyloxytrimethylsilane and Fmoc-(S-t-Bu)-cystine were used for surface modification. After cleavage of protective groups Fmoc and t-Bu, semiconductor nanoparticles were immobilized by self-assembly on filter surface. The immobilization can be explained according to commonly used ligand-exchange reactions. This technique results in strongly fluorescent surfaces presenting an additional amino-group for further functionalization. The obtained membranes are suitable for various diagnostic applications like multi-parameter immunoassays and array applications at nanoscale.

Porous Anodic Aluminum Oxide: Anodization and Templated Synthesis of Functional Nanostructures

“…Decoration of inorganic nanoparticles on the pore wall surface of AAO often imparts new properties to porous AAO. This decoration can be facilitated by surface modification of the pore wall surface with an organic monolayer or polymer, − but can also be achieved directly on the AAO. ,, Ko and Tsukruk immobilized AuNPs on pore walls modified with poly­(diallydimethylammonium chloride) (PDDA) polyelectrolyte by passing cetyltrimethylammonium bromide (CTAB)-stabilized AuNP solution through the AAO membrane. On an explosive molecule, 2,4-dinitrotoluene, the AuNP-decorated AAOs with 3D nanochannel arrays exhibited Raman enhancement with a factor of about 10 5 , as compared to that observed on a AuNP monolayer with identical surface densities of AuNPs.…”

Orthogonal Functionalization of Nanoporous Substrates: Control of 3D Surface Functionality

“…Hence, this strategy prevents the study of processes occurring within the porous network using various optical methods. Silane-based orthogonal functionalizations of AAO appear to be well-suited to circumvent this problem, − but challenging to implement because spatial selectivity is difficult to achieve. Voelcker and co-workers report on a silane-based strategy to selectively functionalize the aluminum surface before the anodization process that generates AAO, which results in a selective functionalization of the pore rims.…”

Layer-by-Layer Quantum Dot Constructs Using Self-Assembly Methods

“…For example, it has been shown that encapsulation of quantum dots into layer-by-layer polymer films on the substrate surfaces resulted in the enhanced photoemission of quantum dots . Similarly, it has been shown using silane chemistries with both Fmoc- and t -butyl protection groups on aluminum oxide membranes provided a method to simultaneously immobilize enzymes or antibodies with the quantum dots …”