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Issue 7, 2015
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Luminescent platinum(ii) complexes with self-assembly and anti-cancer properties: hydrogel, pH dependent emission color and sustained-release properties under physiological conditions

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Abstract

Supramolecular interactions are of paramount importance in biology and chemistry, and can be used to develop new vehicles for drug delivery. Recently, there is a surge of interest on self-assembled functional supramolecular structures driven by intermolecular metal–metal interactions in cellular conditions. Herein we report a series of luminescent Pt(II) complexes [Pt(C^N^Npyr)(C[triple bond, length as m-dash]NR)]+ [HC^N^Npyr = 2-phenyl-6-(1H-pyrazol-3-yl)-pyridine)] containing pincer type ligands having pyrazole moieties. These Pt(II) complexes exert potent cytotoxicity to a panel of cancer cell lines including primary bladder cancer cells and display strong phosphorescence that is highly sensitive to the local environment. The self-assembly of these complexes is significantly affected by pH of the solution medium. Based on TEM, SEM, ESI-MS, absorption and emission spectroscopy, and fluorescence microscopy together with cell based assays, [Pt(C^N^Npyr)(C[triple bond, length as m-dash]NR)]+ complexes were observed to self-assemble into orange phosphorescent polymeric aggregates driven by intermolecular Pt(II)–Pt(II) and ligand–ligand interactions in a low-pH physiological medium. Importantly, the intracellular assembly and dis-assembly of [Pt(C^N^Npyr)(C[triple bond, length as m-dash]NR)]+ are accompanied by change of emission color from orange to green. These [Pt(C^N^Npyr)(C[triple bond, length as m-dash]NR)]+ complexes accumulated in the lysosomes of cancer cells, increased the lysosomal membrane permeability and induced cell death. One of these platinum(II) complexes formed hydrogels which displayed pH-responsive and sustained release properties, leading to low-pH-stimulated and time-dependent cytotoxicity towards cancer cells. These hydrogels can function as vehicles to deliver anti-cancer agent cargo, such as the bioactive natural products studied in this work.

Graphical abstract: Luminescent platinum(ii) complexes with self-assembly and anti-cancer properties: hydrogel, pH dependent emission color and sustained-release properties under physiological conditions

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Supplementary files

Article information


Submitted
24 Nov 2014
Accepted
13 Apr 2015
First published
28 Apr 2015

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2015,6, 3823-3830
Article type
Edge Article

Luminescent platinum(II) complexes with self-assembly and anti-cancer properties: hydrogel, pH dependent emission color and sustained-release properties under physiological conditions

J. L. Tsai, T. Zou, J. Liu, T. Chen, A. O. Chan, C. Yang, C. Lok and C. Che, Chem. Sci., 2015, 6, 3823 DOI: 10.1039/C4SC03635B

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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