pH-Triggered and Targeted Delivery of Curcumin: From Dendritic Polymers to Natural and Synthetic Nanocarriers.

Curcumin, a bioactive compound with broad therapeutic potential, faces critical challenges in clinical translation due to its low water solubility, poor bioavailability, and rapid metabolism. This review provides a comprehensive and critical overview of recent advances in curcumin delivery systems, with a particular emphasis on dendritic polymer-based strategies and pH-responsive formulations. We first highlight the rational design and fabrication of curcumin-dendrimer conjugates through self-assembly and covalent coupling, emphasizing their enhanced targeting efficiency, stability, and intrinsic fluorescence for bioimaging applications. Next, we explore how dual-function systems-integrating pH sensitivity with co-delivery or imaging functions-can overcome conventional delivery barriers. Special attention is given to nanoformulations using natural polysaccharides and Eudragit coatings that enable controlled, site-specific release in acidic tumor microenvironments. By evaluating current limitations and proposing future directions, this review aims to inspire the development of more robust, multifunctional, and clinically translatable curcumin-based nanotherapeutics.