Medical-Oriented Multifunctional Janus Heterostructure Films: Integrated Design for Electromagnetic Shielding, Thermal Regulation, and Antibacterial Triple Functionality.

The increasing prevalence of high-frequency electromagnetic interference (EMI) and bacterial contamination in medical environments demands multifunctional shielding materials that integrate EMI shielding, thermal management, and antimicrobial properties. Herein, an asymmetric trilayer composite film is fabricated via in situ growth of CuS nanoparticles on bacterial cellulose (CuS@BC) and vacuum-assisted assembly with Ti3C2Tx MXene and BC/Fe3O4 layers. The resulting structure exhibits an exceptional EMI shielding effectiveness of 67.5 dB in the X-band, enabled by a synergistic "reflection-absorption-reabsorption" mechanism. The film also demonstrates dual-mode thermal management, achieving 72.6 °C under Joule heating (at 2.0 V) and 126.6 °C under NIR irradiation (808 nm, 1.0 W/cm2). Furthermore, it shows broad-spectrum antibacterial efficacy exceeding 99.9% against both Staphylococcus aureus and Escherichia coli, without compromising shielding performance. This work provides a new paradigm for flexible multifunctional materials suited to advanced medical electronic applications.