Stimuli-responsive polymer-metal-organic framework composites for biomedical applications

Widespread use of metal-organic frameworks (MOFs) is limited by concerns about their structural adaptabilities, stabilities, and durabilities. Extensive research in this area has explored combining MOFs with polymers to form composite materials that exhibit the adaptable characteristics, such as flexibility, biocompatibility, and processability, of MOFs and address the abovementioned issues. To improve the dispersions, solubilities, and durabilities of these systems under physiological conditions, two primary categories of these composites, namely polymer-embedded and polymer-grafted hybrids, have been developed. Multifaceted nature of these platforms has enabled their use in a wide range of biomedical applications. Despite these advances, previous studies have not systematically examined the stimuli-responsive (SR) mechanisms or biomedical performances of polymer systems, MOFs, and corresponding hybrid counterparts. Accordingly, this review focuses on the stimuli-induced functional mechanisms of MOFs and polymer-MOF hybrids for healthcare and diagnostic applications. The objectives of this review are as follows: (i) comparing SR polymers and MOF-based systems in terms of responsiveness and biomedical functionality; (ii) summarizing recent advances (2023-2026), coordination bond instability, framework degradation under physiological conditions, and sensitivity activators, such as light, pH, and redox conditions, which may affect structural integrity and therapeutic performance; (iii) describing external mechanisms based on the use of light, heat, and magnetic platforms for precision therapy; and (iv) discussing significant challenges related to framework integrity, synthetic difficulties, flexibility, and material design and offering guidance for computation.