Biodegradable and biocompatible poly(lactic acid) optical fibers for fiber-guided photothermal therapy of breast cancer cells in vitro.

Breast cancer remains one of the leading causes of cancer-related mortality among women worldwide, while conventional clinical treatments are often limited by high invasiveness, severe side effects, and insufficient spatial control over therapeutic energy delivery. Fiber-based optical platforms offer a compelling strategy for minimally invasive photothermal therapy by enabling precise and localized light transmission within biological tissues. Here, we report a scalable extrusion-thermal drawing strategy for fabricating biodegradable and biocompatible poly(lactic acid)-based optical fibers (BPOFs) and demonstrate their application as biodegradable optical waveguides for fiber-mediated photothermal ablation of breast cancer cells. Owing to the intrinsic biodegradability and biosafety of poly(lactic acid), the resulting BPOFs exhibit excellent structural uniformity, mechanical flexibility, and efficient near-infrared light guidance, with a low propagation loss of 0.33 dB cm-1 at 808 nm. By integrating indocyanine green (ICG) at the distal fiber interface as a photothermal transduction layer, the system enables efficient optical-to-thermal energy conversion and spatially confined heat generation under near-infrared laser irradiation. In vitro studies reveal that BPOF-guided photothermal treatment induces a pronounced time-dependent cytotoxic effect on MCF-7 breast cancer cells, leading to significant suppression of cell viability. Collectively, this work highlights biodegradable polymer optical fibers as a versatile photonic interface for controllable light-tissue interaction, with promising potential for future minimally invasive photothermal applications.