Morphology Engineering of Aggregation-Induced Emission-Based Metal–Organic Frameworks Templated with Cellulose Nanocrystals for Lactic Acid Detection

Strategic morphology engineering of metal–organic frameworks (MOFs) confers on them intriguing functionalities and expanded applications. Herein, we constructed a series of luminescent MOF composites (MOF@CNCs), through in situ growing of aggregation-induced-emission luminogen (AIEgen)-based MOFs onto cellulose nanocrystals (CNCs). By adjustment of the CNC contents, the morphology of MOF@CNCs can be precisely regulated, evolving from needle-like to rod-like and ultimately to flake-like structures resembling floral nanoclusters. Notably, MOF@CNCs performed a pronounced fluorescence enhancement response to lactic acid (LA), a significant biomarker. Particularly, MOF@CNC-1 exhibited superior sensitivity, surpassing other MOF@CNCs with a linear detection range of 0–70 mM for LA, which fully covered the physiological concentration of 2–20 mmol/L during the transition from rest to intense physical activity. Taking advantage of the distinctive sensitivity of the MOF@CNC-1 suspension, we developed fluorescent test strips for assessing LA level quantitatively. This work introduced a strategy to design MOF composites, leveraging CNC templating to enhance the photoluminescence sensing performance for biomarkers.