Water-soluble conjugated polymeric micelles as a carrier for studying Pt(iv) release and imaging in living cells

Abstract

Here, polyethylene glycol (PEG) was fixed on the side chains of a poly(p-phenyleneethynylene) (PPE) core via an esterification reaction, thus forming hydrophilic conjugated polymeric micelles (CPMs). Due to the alkynyl group of the main chain of PPE, the micelles can coordinate with platinum ions to form platinum-substituted cyclopropene structures, and these water-soluble CPMs can act as carriers of Pt(IV). Meanwhile, because Pt(IV) can also quench the fluorescence of the PPE main chain, Pt(IV) loading content can be detected through the degree of CPM fluorescence quenching. Cell experiments show that the CPMs have low toxicity and can preferentially distribute in the cell nucleus. Therefore, the CPMs, as Pt(IV) carrier, can eliminate the shortcomings of some platinum compounds, which do not have nuclear targeting capability in cells. Furthermore, the PPE fluorescence recovers after Pt(IV) is captured in the cell nucleus. In this work, the CPMs have been applied to carry Pt(IV) into MCF-7 cells. The results show that Pt(IV) is directly delivered to the cell nucleus and bound by DNA, because the PPE fluorescence is again observed in the cell nucleus. After 24 h, obvious apoptosis can be observed, indicating that Pt-DNA coordination efficaciously blocks DNA replication, transcription, and cell division. We believe that this kind of platinum carrier will have good application prospects in the field of tumor chemotherapy and imaging.