Dual-Dye Nanoparticle Inks for Multimodal Visualization in Surgical Applications

High Resolution Image Download MS PowerPoint Slide Multimodal imaging agents that improve the sensitivity and specificity of tissue visualization in surgery are critical for improving patient care outcomes. Single-modality dyes and nanoparticles have been adopted for tissue marking and visualization, including endoscopic and laparoscopic visualization. Engineering effective multimodal contrast agents has the potential to enhance the accuracy of detection and visualization in surgical procedures while reducing or eliminating tissue interference. Furthermore, expanding the detection range of formulations used in surgical visualization can enhance the flexibility of this approach and facilitate their wider adoption. Here, we describe a dual-dye (DD) nanoparticle ink (DD-Ink) formulated with Rose Bengal and Indocyanine Green, encapsulated in a derivatized chitosan nanoparticle matrix. The DD-Ink formulation forms a stable, dark-colored, injectable suspension that provides excellent tissue contrast under white light. In addition, the use of dual dyes results in inks that absorb light across both the visible and near-infrared (NIR) regions of the absorption spectrum and facilitate contrast against white light. Nanoparticle encapsulation resulted in uniquely broad, plateau-like absorption across the near-infrared (NIR) wavelength range of 650–900 nm for ICG and DD-Ink, which, to our knowledge, is not seen in current imaging agents. DD-Ink did not stimulate key inflammatory signaling in macrophages in vitro and demonstrated excellent spatial localization, contrast to white light, and fluorescence emission in ex vivo tissue. The ability of these inks to absorb NIR light enabled effective photoacoustic imaging and photothermal activation across multiple NIR wavelengths. Injections in live mice demonstrated that the DD-Ink did not cause adverse reactions and exhibited dual-imaging capability, with visualization under both white-light and fluorescence modalities. Our findings indicate that the DD-Ink provides strong NIR absorption over a wide range and enables multimodal imaging, i.e., white-light contrast, NIR fluorescence, and photoacoustic contrast, in vitro and ex vivo models.