Small molecule fluorophores often face challenges such as short blood half-life, limited physicochemical and optical stability, and poor pharmacokinetics. To overcome these limitations, we conjugated the zwitterionic near-infrared fluorophore ZW800-PEG to human serum albumin (HSA), creating HSA-ZW800-PEG. This conjugation notably improves chemical, physical, and optical stability under physiological conditions, addressing issues commonly encountered with small molecules in biological applications. Additionally, the high molecular weight and extinction coefficient of HSA-ZW800-PEG enhances biodistribution and tumor targeting through the enhanced permeability and retention effect. The unique distribution and elimination dynamics, along with the significantly extended blood half-life of HSA-ZW800-PEG, contribute to improved tumor targetability in both subcutaneous and orthotopic xenograft tumor-bearing animal models. This modification not only influences the pharmacokinetic profile, affecting retention time and clearance patterns, but also enhances bioavailability for targeting tissues. Our study guides further development and optimization of targeted imaging agents and drug-delivery systems.

Despite significant advancements in bioimaging technology, only a limited number of fluorophores are currently approved for clinical applications. Indocyanine green (ICG) is the first FDA-approved near-infrared (NIR) fluorophore and has significantly advanced clinical interventions over the past three decades. However, its single-channel imaging at 800 nm emission is often insufficient for capturing comprehensive diagnostic information during surgery. In this study, we evaluate indocyanine blue (ICB), an ICG analog with a shorter polymethine bridge, as a promising candidate for multi-channel NIR imaging. ICB demonstrated peak absorption and emission approximately 100 nm shorter than ICG in aqueous solutions, placing it within the 700 nm range of the NIR window. Furthermore, ICB exhibited favorable solubility and optical properties in aqueous environments, supporting its potential for in vivo imaging applications. Notably, ICB shows rapid systemic clearance, likely due to its lower molecular weight, which facilitates clear visualization in angiography, cholangiography, and lymph node mapping with minimal background interference. Additionally, dual-channel imaging of tumors and lymph nodes was achieved using a tumor-targeting fluorophore in conjunction with ICB, illustrating the potential for enhanced intraoperative guidance. ICB emitting at 700 nm, therefore, can be useful in NIR imaging, broadening the possibilities for improved diagnostic accuracy and therapeutic outcomes in clinical settings.

Autodynamic cancer therapy possesses tremendous potential for enhancing therapeutic efficacy by initiating the treatment process autonomously within targeted cells. However, challenges related to biocompatibility and targeted delivery have hindered its clinical translation owing to the induction of adverse effects and cytotoxicity in healthy cells. In this study, a novel approach for auto‐initiated dynamic therapy by conjugating zwitterionic near‐infrared fluorophores to a cell‐penetrating peptide is proposed. This enables efficient cellular uptake and specific targeting of therapy to desired cells while avoiding off‐target uptake. The zwitterionic bioconjugate causes cancer‐specific toxicity following its internalization into the targeted cells, triggered by specific intracellular conditions in lysosomes. This innovative approach enables selective targeting of lysosomes in malignant cells while minimizing cytotoxic effects on normal cells. By targeting lysosomes, the method overcomes inherent risks and side effects associated with conventional cancer treatments, offering a selective and effective approach to cancer therapy.