Specific, sensitive, and reliable sensing of cancer cells based on quantum dot/hydrogel-coated double optical fiber ball

For clinical applications, a sensor of cancer cells should exhibit high sensitivity, have a small and robust sensing structure, and exhibit good anti-interference. This paper presents a novel biosensor for the recognition and concentration detection of biotin receptor (BR)-overexpressed cancer cells. This biosensor uses a hydrogel composed of biotin-quantum dots (BQDs) grafted onto oxidized sodium alginate with carboxymethyl chitosan (BQDs-g-OSA/CMCS) and a double optical fiber ball (DOFB) sensing structure. The developed BQDs-g-QSA/CMCS hydrogel exhibited specific recognition capabilities for cancer cells and an excellent fluorescence stability. Meanwhile, the proposed DOFB structure was small and presented a strong robustness and integrated fluorescence excitation and reception, which are favorable for in vivo sensing. In addition, in-depth study of the sensing performance of the sensor was conducted by utilizing streptavidin (SV) protein and BR-overexpressed cancer cells (leukemia cells, K562). The experimental results revealed a linear relationship between the photoluminescence intensity of the sensor and concentrations of SV and K562, with minimum detection concentrations of 1.62 nM and 1.0 × 103 cells/mL, respectively. In addition, the specificity of the sensor was confirmed through investigation of the its response to another BR-overexpressed cancer cell type (lung cancer cells, A549) and normal cells (human gastric mucosal epithelial, GES-1). The sensor exhibited similar responses to A549 as to K562 cells but not to GES-1 cells, which indicates its specificity toward cancer cells with BR overexpression. In summary, the proposed sensor offers important potential for applications in cancer diagnosis and treatment.