Cell‐Penetrating Peptide‐Conjugated BF₂‐Oxasmaragdyrins as NIRF Imaging and Photothermal Agents

Abstract

Cell-penetrating peptides (CPPs) are excellent cell internalizing agents for hydrophobic drug/dye moieties. We exploited this property of CPPs for the cell internalization of BF 2-oxasmaragdyrin by constructing covalent conjugates of BF 2-oxasmaragdyrin with CPPs (CRGDK and polyarginine (R 9)) using a solidphase peptide synthesis (SPPS) methodology. The CPP-conjugated BF 2-oxasmaragdyrins were purified by reversed-phase HPLC and characterized by mass spectrometry. The CPPconjugated BF 2-oxasmaragdyrins were found to be photostable, absorb in the visible-NIR region (400-700 nm), emit in the NIRÀ I region (~715-720 nm) with moderate quantum yields, and be biocompatible, with excellent cellular imaging potential in breast cancer cells (MDA-MB-231). The R 9 conjugate, being the first water-soluble BF 2-oxasmaragdyrin, also possesses excellent photothermal transduction efficacy with 750 nm laser irradiation and is a potential theranostic agent.

BF2-Oxasmaragdyrin Nanoparticles: A Non-toxic, Photostable, Enhanced Non-radiative Decay-Assisted Efficient Photothermal Cancer Theragnostic Agent

“…The 25-oxasmaragdyrins absorb and emit in the vis–NIR region with moderate quantum yields and singlet state lifetimes. The photophysical properties were further improved by synthesizing BF 2 - and PO 2 -complexes of 25-oxasmaragdyrins. , Though these molecules have good photophysical properties, their potential for biological applications was not explored due to their poor aqueous solubility. − A perusal of literature revealed that various dye-based formulations have been employed for NIRF imaging and in photothermal therapeutic applications. − …”

Bioinspired carrier-free peptide conjugated BF2-oxasmaragdyrin dye-based nano self-assemblies: a photostable NIR cancer theragnostic agent

“…The 25-oxasmaragdyrins absorb and emit in the Vis-NIR region with moderate quantum yields and singlet state lifetimes. Recently, our group reported the synthesis of BF 2 -and PO 2 -complexes of 25-oxasmaragdyrins [28][29][30] , which exhibit improved photophysical properties compared to those of freebase 25-oxasmaragdyrin, and the NIRF imaging potential has been demonstrated 31,32 .…”