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Tumor-Targeted Squaraine Dye for Near-Infrared Fluorescence-Guided Photodynamic Therapy
Yoonbin Park1,2, Min Ho Park3, Hoon Hyun1,2
1Department of Biomedical Sciences, Chonnam National University Medical School, Hwasun 58128, Republic of Korea.
Abstract:
Many efforts have been made to develop near-infrared (NIR) fluorescent dyes with high efficiency for the NIR laser-induced phototherapy of cancer. However, the low tumor targetability and high nonspecific tissue uptake of NIR dyes in vivo limit their applications in preclinical cancer imaging and therapy. Among the various NIR dyes, squaraine (SQ) dyes are widely used due to their high molar extinction coefficient, intense fluorescence, and excellent photostability. Previously, benzoindole-derived SQ (BSQ) was prepared by incorporating carboxypentyl benzoindolium end groups into a classical SQ backbone, followed by conjugating with cyclic RGD peptides for tumor-targeted imaging. In this study, we demonstrate that the structure-inherent tumor-targeting BSQ not only shows a high fluorescence quantum yield in serum but also exhibits superior reactive oxygen species (ROS) generation capability under the 671 nm laser irradiation for effective photodynamic therapy (PDT) in vitro and in vivo. Without targeting ligands, the BSQ was preferentially accumulated in tumor tissue 24 h post-injection, which was the optimal timing of the laser irradiation to induce increments of ROS production. Therefore, this work provides a promising strategy for the development of photodynamic therapeutic SQ dyes for targeted cancer therapy.
Insights
Researchers developed a novel near-infrared squaraine (SQ) dye that targets tumors effectively for cancer photodynamic therapy (PDT). This structure-inherent targeting dye shows high efficiency in generating reactive oxygen species (ROS) for cancer treatment.
Area of Science:
- Biomedical Engineering
- Materials Science
- Oncology
Background:
- Near-infrared (NIR) fluorescent dyes are crucial for cancer phototherapy but often suffer from poor tumor targeting and high uptake by healthy tissues.
- Squaraine (SQ) dyes offer high molar extinction coefficients, intense fluorescence, and photostability, making them promising candidates for NIR applications.
- Previous benzoindole-derived SQ (BSQ) dyes required conjugation with targeting ligands for tumor specificity.
Purpose of the Study:
- To develop a novel BSQ dye with inherent tumor-targeting capabilities for enhanced cancer photodynamic therapy (PDT).
- To evaluate the in vitro and in vivo efficacy of the BSQ dye in generating reactive oxygen species (ROS) upon laser irradiation for cancer treatment.
Main Methods:
- Synthesis of a novel benzoindole-derived squaraine (BSQ) dye with inherent tumor-targeting properties.
- Assessment of the BSQ dye's fluorescence quantum yield in serum and its reactive oxygen species (ROS) generation under 671 nm laser irradiation.
- In vitro and in vivo evaluation of the BSQ dye's tumor accumulation, biodistribution, and therapeutic efficacy in a preclinical cancer model.
Main Results:
- The BSQ dye demonstrated a high fluorescence quantum yield in serum.
- The BSQ dye exhibited superior reactive oxygen species (ROS) generation under laser irradiation, crucial for effective photodynamic therapy (PDT).
- Without specific targeting ligands, the BSQ dye preferentially accumulated in tumor tissues 24 hours post-injection, indicating optimal timing for laser treatment and enhanced ROS production.
Conclusions:
- The developed BSQ dye possesses intrinsic tumor-targeting capabilities, overcoming limitations of traditional NIR dyes.
- This BSQ dye is a promising candidate for targeted cancer photodynamic therapy (PDT) due to its efficient ROS generation and preferential tumor accumulation.
- The study presents a novel strategy for designing effective photodynamic therapeutic SQ dyes for targeted cancer treatment.
