Construction\nof a Three-Dimensional-Printed Immunosensing\nPlatform Based on Smartphone Photothermal Signal Integration

The combination of the photothermal effect and immunoassay\nserves\nas a potent tool for crafting cost-effective and user-friendly biosensing\nsystems. To ensure efficient light-to-heat conversion, we integrated\nthree-dimensional-printed (3D printed) technology to devise a novel\ndesign. This design functions as the structural support for both the\ncell phone and laser probe, as well as a means for sample handling.\nThe main body features a three-way cavity structure, securing the\ntest sample at a fixed position to maintain consistent light distance\nand angle, thereby minimizing testing errors. Card slot insert facilitates\nprecise sample positioning to ensure the adequacy of receiving light.\nThe sample holder’s wide front and narrow back design enables\nthe accommodation of fixed samples while providing a broad field of\nview, with intervals therein effectively preventing cascading heat.\nOur design employs MB@MOF235 (methylene blue adsorbed by iron terephthalate)\nas the photothermal reagent, successfully enabling the detection of\nα-fetoprotein (AFP). The detection range spans from 0.01 to\n50 ng/mL, with a lower detection limit (LOD) of 0.032 pg/mL. The detection\nmethod, combining simplicity, portability, and visualization, offers\na reliable reference for furthering precision medicine toward personalized\nmedicine. Meanwhile, to verify the method’s accuracy electrochemical\ntesting was conducted to support the proof using the electro-oxidizing\nactivity of MB.