Biocompatibility and cytotoxicity of novel photoinitiator π-conjugated dithienophosphole derivatives and their triggered polymers.

Photoinitiators have widely been applied to industry, and now increasingly to clinical therapy. A novel high-performance photoinitiation system based on π-conjugated dithienophosphole derivatives (DTPs), including Ph-DTP and TPA-DTP, has recently been developed with high extinction coefficients and amazing polymerization initiating abilities at a relatively low dose in both the near-UV and visible light ranges, and TPA-DTP has better absorption characteristics than Ph-TPA. The purpose of this study was to evaluate cytotoxicity of DTPs and cytocompatibility of their initiated polymers by a MTT assay and calcein AM/propidium iodide staining. The cytotoxicity of Ph-DTP or TPA-DTP exposed to non-irradiation or irradiation is lower than bis (2,4,6-trimethylbenzoyl)-phenylphosphine oxide (BAPO) applied widely to industry. No obvious cytotoxicity was observed in the TPA-DTP-treated primary cells and various cell lines, while the activated Ph-DTP inhibited the cell viability and resulted in the massive cellular apoptosis and necrosis. Compared to camphorquinone (CQ) applied widely to clinical dental prosthetic restoration, the cytocompatibility of DTPs-photopolymerized BisGMA/TEGDMA polymers was inferior to CQ although their extracts exhibited low toxicity, indicating that TPA-DTP but not Ph-DTP is more suitable for industrial application. These results provide a novel insight into underlying potential application of DTPs to industrial deep polymerization or clinical tissue engineering rehabilitation.