Green luminescent, monodisperse, smooth, porous and hollow spheres were simply prepared by Cu(2+) and temperature mediated oxidative coupling assembly of green tea polyphenols in water. These polymeric tea polyphenol spheres are GSH responsive, acid resistant but alkali-responsive, ideally used as platform for controlled delivery of functional guests.
Nanoformulations offer the opportunity to overcome the shortcomings of drug molecules, such as low solubility, side effects, insufficient stability, etc., but in most of the current nanomedicines, nanocarriers as excipients do not directly participate in the therapy procedure. Accordingly, it is promising to develop the nanotherapeutics composed entirely of pharmaceutically active molecules. Tea polyphenols, especially epigallocatechin gallate (EGCG), are a kind of natural antioxidants with various biological and health beneficial effects and are extensively investigated as nutrients and anticancer drugs. Here, the sizetunable and highly active polyphenol nanoparticles were conveniently synthesized in water and could be massively produced with a simple facility. Compared to the previous strategies, either molecular assembly via oxidative coupling or combination with other biomacromolecules, the present preparation was conducted by the amino acid-triggered Mannish condensation reactions, thus permitting the flexible molecular design of various polyphenol nanoparticles by selecting different amino acids. This straightforward and ultrafast method actually opens up a novel means to make use of naturally reproducible polyphenols. Moreover, inheriting the salient properties of EGCG, these nanoparticles show strong antioxidation capacity, 10-fold higher than the extensively investigated polydopamine nanoparticles, and they are biosafe but have therapeutic effects, according to the in vitro and in vivo assessments of anticancer activity, which is promising for various biomedical purposes.
Various nanotechnologies have been extensively developed to prepare nanoparticles with different features for satisfying the requirements of diverse fields, but the current achievements are confined to different material systems for the limited acquisition with desirable properties. Here, we demonstrated a flexible strategy based on the broad selectivity of amines in the condensation of green tea polyphenol-EGCG (epigallocatechin gallate), formaldehyde, and amines for the rational design and preparation of versatile nanomaterials. With EGCG as the sole material system and amines (R−NH 2 ) of various functional R groups as the selectable modules, the modular assembly of polyphenolactivated condensation was straightforward and completed in one step, giving rise to different polyphenolic nanoparticles variable in surface chemistry (−amine, −aldehyde, and −carboxyl), shapes (sphere, dumbbell, walnut), internal structures (solid, hollow, and porous), stimuli responsiveness (-s-s-), and fluorescence. The flexibility of the polyphenolic condensation for versatile nanoparticles was further demonstrated by the incorporation of amino-containing anticancer or antibacterial drugs into polyphenolic nanoparticles as nanodrugs. The present study totally involved the use of 13 different amines to synthesize 18 different nanoparticles, not only convincingly specifying the enormous value of the polyphenolic condensation as platform for modular assembly of versatile nanoparticles but also revolutionizing the current strategies and methodologies for encapsulated applications of tea polyphenols.
Molecular assembly of green tea polyphenols and keratins into size-controlled, colloidally stable and functional nanoparticles for enhanced cancer therapy was achieved.
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