Resorbable optical fibers for interstitial photodynamic therapy-assessment of photosensitizer spatial distribution in tumors.

Abstract

Significance: Optical-quality bioresorbable implants, which gradually dissolve within the body, are gaining increasing interest due to their potential to eliminate the need for revision surgeries. These implants show significant promise in treating deep-seated tumors in high-risk areas, such as the brain, and offer extended capabilities for monitoring interstitial physiological parameters or pharmacokinetics through photonic technologies.

Aim: A proof-of-principle validation has been conducted on calcium phosphate glass (CPG)-based bioresorbable optical fibers to assess their capability to monitor the spatial distribution of photosensitizing (PS) drugs in tumors-an essential parameter to optimize for enhanced treatment outcomes in photodynamic therapy (PDT).

Approach: Ex vivo validation was performed on liquid phantoms with solid tumor-mimicking inclusions containing the fluorescent PS drug. In-house developed bioresorbable fibers, with optical characteristics similar to silica fibers used in current PDT systems, were utilized. For the first time, these fibers were used for the interstitial acquisition of fluorescent signals, followed by the tomographic reconstruction of the drug distribution in the phantom. The results were compared with those obtained from a standard clinical system equipped with silica fibers.

Results: The reconstructed drug distribution with bioresorbable fibers agreed with that obtained using the same system with standard silica fibers.

Conclusions: We reveal the potential of further exploring CPG bioresorbable optical fibers for interstitial PDT.