Multiple dyes applications for fluorescent convertible polymer capsules as macrophages tracking labels

Area of Science:

• Biotechnology and Biomedical Engineering
• Cell Biology and Imaging

Background:

• Tracing individual cell pathways is vital for understanding cell behavior, communication, migration, and fate.
• Current optical labeling methods often rely on genetic modification, which is unsuitable for certain cell types like macrophages due to toxicity.

Purpose of the Study:

• To develop an alternative, non-genetic method for labeling macrophages using photoconvertible micron-sized capsules.
• To evaluate the efficacy, safety, and applicability of these capsules for individual cell tracking.

Main Methods:

• Scalable synthesis of micron-sized capsules using thermal treatment in polyvinyl alcohol gel, encapsulating various fluorescent dyes.
• Evaluation of capsule properties (fluorescence, photostability, photoconversion) using confocal laser scanning microscopy.
• Cellular studies on RAW 264.7 and bone marrow-derived macrophages to assess viability, uptake, mobility, and photoconversion.

Main Results:

• Capsules containing rhodamine B and rhodamine 6G demonstrated suitable brightness, photostability, and photoconversion for intracellular use.
• Mass spectrometry revealed deethylation leading to spectral blue shifts upon irradiation.
• Macrophages showed robust capsule uptake with minimal cytotoxicity and negligible impact on cell motility.

Conclusions:

• Photoconvertible micron-sized capsules serve as a viable alternative to photoconvertible proteins for individual cell labeling, particularly in macrophages.
• This novel labeling strategy holds significant potential for advancing research in cell dynamics and personalized medicine.