Reaching Biocompatibility with Nanoclays: Eliminating the Cytotoxicity of Ir(III) Complexes

Abstract

Cyclometalated Ir complexes are promising candidates for biomedical applications but high cytotoxicity limits their use as imaging and sensing agents. We herein introduce the use of Laponite as carrier for triplet-emitting cyclometalated Ir complexes. Laponite is a versatile nanoplatform because of its biocompatibility, dispersion stability and large surface area that readily adsorbs functional nonpolar and cationic molecules. These inorganic-organic hybrid nanomaterials mask cytotoxicity, show efficient cell uptake and increase luminescent properties and photostability. By camouflaging intrinsic cytotoxicity, this simple method potentially extends the palette of available imaging and sensing dyes to any metal-organic complexes, especially those that are usually cytotoxic.

Intermolecular Interactions and Self-Assembly in Pt(II) Complex–Nanoclay Hybrids as Luminescent Reporters for Spectrally Resolved PLIM

“…27 Supramolecular scaffolding offers additional benefits, as the hybrids formed by adsorption onto nanoclays are known to stabilize triplet states by reducing vibrational relaxation resulting in prolonged τ and enhanced Φ L . 19,28 Our previous studies involving LAP-based hybrids with aluminum(III) or silicon(IV) phthalocyanines demonstrated their improved photophysical properties in H 2 O, if compared with the native chromophores. 29,30 Gruner et al…”

“…18 Interestingly, both aqueous solubility and 3 O 2 insensitivity can be also achieved employing layered nanoclays such as Laponite (LAP) as carriers for phosphorescent species. 19 LAP constitutes a transparent nanocarrier with a high aspect ratio. 20 LAP has been extensively used in biomedical applications such as drug delivery, 21,22 bioimaging, 23,24 ative medicine.…”

“…have also reported on the use of LAP as a nanocarrier for Ir(III) complexes, masking the cytotoxicity of the coordination compounds and enhancing both their photophysical properties and their photostability. 19 Recently, we reported on the comparative photophysical investigation of such arrays as dry powders and in hydrogels to demonstrate the importance of H 2 O in tuning the excited-state properties, which were dominated by the bulk of the ligands affecting the interaction between discs and hence between the adsorbed molecular entities. 31 In the present article we examine the capabilities of such hybrids in dilute aqueous dispersions and demonstrate the relevance of intermolecular interactions on the nanodiscs' self-assembly, which in turn affect intermolecular coupling as well as the resulting photophysical, colloidal, and morphological properties.…”

“…This result indicates that the hybrids were internalized by the cells during the coincubation, since the luminescence signal would be more evenly distributed if the nanodiscs were nonspecifically attached to the outer surface of the cells, as it was previously reported in the bibliographic literature. 19 The investigation of the exact location, uptake mechanism of the hybrids, and the possible trafficking to various intracellular destinations can be very complex 39 and is the object of ongoing investigation.…”

Binary Mixtures of Colloidal Cellulose Nanocrystals and Laponite for Preparation of Functional Nanocomposites

“…Meanwhile, inorganic nanofillers have gained prominence nowadays, especially layered aluminosilicates used extensively in polymer nanocomposites 38,39 . Among them, Laponite, a synthetic clay mineral having a disk shape morphology, possesses appealing properties like biocompatibility 40 , hydrophilicity 41 and biodegradability 42 . A positive charge deficiency is created in the Laponite sheet by substituting lithium atoms in place of few magnesium atoms in the octahedral layer (Scheme 1) [43][44][45] .…”