An ALP-responsive, anionic iridium complex for specific recognition of osteosarcoma cells.

Area of Science:

• Coordination Chemistry
• Biomedical Diagnostics
• Materials Science

Background:

• Anionic Iridium(III) complexes are emissive and stable but suffer from poor cellular permeability, limiting their use in cell-based diagnostics.
• Osteosarcoma cells overexpress alkaline phosphatase (ALP), presenting a potential target for specific diagnostic agents.

Purpose of the Study:

• To develop an alkaline phosphatase (ALP)-responsive, anionic, aggregation-induced emission (AIE)-active Iridium(III) complex for specific osteosarcoma cell recognition.
• To overcome the cellular permeability barrier of anionic Iridium(III) complexes for enhanced biomedical applications.

Main Methods:

• Design and synthesis of an anionic Iridium(III) complex (Ir1) containing phosphate moieties.
• Investigation of ALP-mediated hydrolysis of Ir1 to a dephosphorylated, positively charged complex (Ir2).
• Evaluation of cellular uptake, biocompatibility, and AIE properties of Ir1 and Ir2 in osteoblast and osteosarcoma cells.

Main Results:

• The anionic Ir1 complex exhibited low cellular uptake and good biocompatibility with normal cells due to charge repulsion.
• ALP-mediated dephosphorylation yielded Ir2, which showed increased lipophilicity and cellular uptake.
• Ir2 activated AIE properties and specifically recognized osteosarcoma cells with high ALP expression.

Conclusions:

• ALP serves as an effective trigger to enhance the cellular permeability of phosphate ester-containing Iridium(III) complexes.
• The developed ALP-responsive Iridium(III) complex shows promise for specific osteosarcoma cell detection in biomedical diagnostics.
• This strategy broadens the application scope of anionic Iridium(III) complexes in advanced biomedical fields.