Multifunctional Cellulose Nanofiber Films With Embedded Highly Oriented MXene Flakes

Ultrathin transparent photonic films that are simultaneously robust, cytocompatible, and actively antimicrobial remain rare. Here, the critical physical properties of freestanding micrometer-thick films composed of layered cellulose nanofibers intercalated with Ti₃C₂T_x MXene nanosheets (CNF-MXene) are established. Correlated co-alignment of MXene flakes with near-perfect in-plane order is achieved in the cellulose nanofiber matrix by vacuum-assisted filtration. The Herman's orientation parameter of MXene nanosheets reaches up to 0.94, approaching the theoretical limit of 1.0 for perfect orientational order. Flow-assisted alignment and nanofiber-mediated confinement are proposed to suppress MXene restacking and lock the unique film architecture into a stable scaffold. This highly ordered structure yields a significant increase in mechanical strength and elastic modulus. Moreover, co-alignment of individual flakes at ultralow volume fractions (below 1%) creates accessible, photothermally active surface sites within optically clear films. As a result, these ultrathin CNF-MXene membranes combine near-infrared-activated photothermal antimicrobial behavior and molecular adsorption of organic dye as a proxy for accessibility, highlighting a distinctive multifunctional platform for active bio-based films with strong potential for wound-healing applications and long-term functionality preservation.