Introduction: The study of triple-negative breast cancer cells detection is one of the important research fields in modern biomedical engineering, due to its aggressive behavior and limited targeting options. One of the promising methods for cancer cell detection is using Molecularly Imprinted Polymers (MIPs) with polydopamine (PDA) as the primary polymer. The main idea of this combination is based on the properties of dopamine, as it shows good compatibility with cells, biomimicry, and biodegradability. By creating specific cell recognition cavities within this PDA-based MIP layer directly on the fiber surface, the platform shows high selectivity level performance. Methods and Materials: Using bulk imprinting strategy, dopamine was polymerized under alkaline conditions, where pH was in range of 8.0-9.0. For control group, the non-imprinted polymers (NIPs) were prepared by mixing phosphate buffer solution (PBS) with PDA, while MIPs were functionalized with HCC1806 and MDA-MB231 cancer cell lines. During detection process, the response groups were divided into two categories: target and cross groups. Optical responses of these groups were determined by using fiber-optic interrogator at different cell concentrations and the morphology was evaluated via scanning electron microscopy. Results and Conclusion: The provided optical fiber technology shows great detection, stability, and biocompatibility levels for novel technology and has a great potential for further development towards the label-free detection platforms’ integration.

Breast cancer remains a major cause of cancer-related mortality in women, and its substantial molecular heterogeneity highlights the need for methods capable of characterizing tumor cells at the cellular level. CD44, a transmembrane glycoprotein associated with breast cancer progression, metastasis, and cancer stem-like phenotypes, is a promising biomarker for selective recognition of aggressive, basal-like cell populations. However, conventional approaches to evaluating CD44 expression including immunohistochemistry, immunofluorescence, and flow cytometry require labeling and multi-step sample preparation. In this work, a gold-coated, polydimethylsiloxane (PDMS)-based extrinsic semi-distributed interferometric (SDI) optical fiber biosensor functionalized with anti-CD44 antibodies was developed for label-free, selective detection of CD44-expressing HCC1806 breast cancer cells. The functionalized sensor exhibited a concentration-dependent response with a limit of detection (LoD) of 2.51 cells/mL, while the antibody-free control sensor exposed to HCC1806 cells and the anti-CD44-functionalized sensor exposed to CD44-low HEK293 cells showed only minimal responses, supporting selective detection under the tested conditions. These results support the potential of the antibody-functionalized ESDI platform for label-free detection of CD44-expressing cells, providing a groundwork for its validation in clinical samples as a step toward tumor-cell diagnostics.