Folate-polyethylene glycol conjugated near-infrared fluorescence probe with high targeting affinity and sensitivity for in vivo early tumor diagnosis

Purpose: The purpose of this study is to synthesize a folate-polyethylene glycol (PEG) conjugated near-infrared fluorescence probe (fPI-01) for diagnosis of folate receptor (FR)-overexpressed tumors with high sensitivity and specificity. Procedures: fPI-01 was synthesized, purified, and characterized. Its cytotoxicity and affinity to tumor cells were determined in vitro. The dynamics and biodistribution of the probe was monitored in normal nude mice. And the tumor-targeting capability was investigated in nude mice bearing different tumor xenograft. Results: fPI-01 was successfully synthesized with strengthened optical properties. Cells experiments showed the probe had high FR affinity and without apparent cytotoxicity. Animal experiments indicated the probe excreted through urine by kidney. And its tumor-targeting ability was demonstrated on different tumor-bearing mice, with high sensitivity and tumor-to-normal tissue contrast ratio (10:1). Conclusions: fPI-01 is a promising optical agent for diagnosis of FR-positive tumors, especially in their early stage.