Rapid Cu(II)-Directed Self Assembly of Esterified Tea Polyphenol Oligomers to Controlled Release Nanoflower Carrier

Abstract

In this study, novel tea polyphenolic-copper hybrid nanoflowers were assembled with tea polyphenol palmitate oligomers generated simply through air oxidation. It was revealed that the growth of tea polyphenolic-based hybrid nanoflowers was notably faster than protein-based ones, presumably owing to rigid polyphenolic molecular architecture and the resultant different growth mechanism. The structures and composition investigation by FT-IR, X-ray, and SEM-EDS unveiled that the whole framework of the nanoflowers was composed of complexes of tea polyphenolic oligomers and copper phosphate crystals. The tea polyphenolic hybrid nanoflowers demonstrated high loading capacity of curcumin due to flower-like porous structure and hydrophobic pockets furnished by lipophilic side chains. The nanoflowers exhibited remarkable protection capacity for carried curcumin from UV irradiation and thermal treatment. Controlled release of the nanoflowers could be readily achieved by adjustment of pH condition. Owing to high assembly efficiency, biocompatibility, and natural abundance, tea polyphenols are intriguing organic components to generate nanoflowers.

Hybrid Nanoflowers Bloom From Disintegrated Food Proteins Towards Natural Pigments Stabilization

“…The growth process of HNFs prepared with SPH at an E/S ratio of 0.15% (Supporting Figure 1) was further recorded for better understanding the formation of HNFs. Upon addition of SPH to phosphate buffer and CuSO 4 solution, primary copper phosphate precipitates are generated first (a, f), which in turn transform into agglomerates within 3 h (b, g), probably facilitated by the coordinating ability of the amide groups in the protein backbone to Cu 2+ . , Meanwhile, the agglomerates can provide locations for nucleation, initiating the growth of HNFs, where scaffolds appear in branched structures. At 12 h, a few HNFs finished their growth, with the scaffold structures becoming plump since proteins serve as the “flesh” to fill the scaffolds (c, h).…”

“…Optical microscopy and scanning electron microscopy (SEM) were used to characterize the morphologies of HNFs; 16,35 energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) were used to determine the hybridization of the protein and metal phosphate to confirm the formation of HNFs. 9,16 We demonstrate that these proteins indeed have poor ability to form HNFs. However, decomposition of these food proteins by enzymatic hydrolysis can markedly promote the formation of highly hierarchical HNFs with different morphologies.…”

“…In addition to the aforementioned applications of HNFs, researchers are also attempting to develop HNFs as delivery systems in most recent years due to the high surface-to-weight ratio property of HNFs. Among organic materials, only polysaccharides and polyphenols have been explored to carry some small biomolecules (e.g., 5-flurouracil and curcumin) for now. Compared to those two types of organic materials, protein is one of the most used biomaterials in the design of delivery systems because it not only can be easily obtained from numerous food resources but also has abundant functional groups that can combine with other biomolecules through hydrophobic interactions, hydrogen bonds, and electrostatic interactions. − Once incorporated into high surface-to-weight ratio HNFs, proteins might have a better stabilization of loaded cargos due to the synergistic effects of immobilized proteins as shown in enzyme protein-based HNFs. − However, the preparation of protein-based HNFs currently mostly employs enzyme proteins for immobilization of enzymes to improve their stability and activity. ,, Food proteins have been rarely found to effectively produce HNFs and are limited to BSA, , concanavalin A, immunoglobulin G, human serum albumin, hemoglobin, and streptavidin using the primitive method as introduced by Ge et al Moreover, in most cases, these proteins are used because of their special enzyme mimicking activities or specific affinity with some substrates (especially antibodies), and the prepared HNFs are mainly applied as biomimetic catalysts or biosensors.…”

“…In this article, we investigate the performance of 11 proteins from common food materials including pulses (pea and mung bean), oil seeds (soy bean and peanut), cereals (oat, rice, and brown rice), root (potato), algae (chlorella), and milk (whey protein and casein) in forming HNFs and the role of enzymatic hydrolysis in improving such capabilities. Optical microscopy and scanning electron microscopy (SEM) were used to characterize the morphologies of HNFs; , energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) were used to determine the hybridization of the protein and metal phosphate to confirm the formation of HNFs. , We demonstrate that these proteins indeed have poor ability to form HNFs. However, decomposition of these food proteins by enzymatic hydrolysis can markedly promote the formation of highly hierarchical HNFs with different morphologies.…”

“…1,11−14 In addition to the aforementioned applications of HNFs, researchers are also attempting to develop HNFs as delivery systems in most recent years due to the high surface-to-weight ratio property of HNFs. Among organic materials, only polysaccharides 15 and polyphenols 16 have been explored to carry some small biomolecules (e.g., 5-flurouracil and curcumin) for now. Compared to those two types of organic materials, protein is one of the most used biomaterials in the design of delivery systems because it not only can be easily obtained from numerous food resources but also has abundant functional groups that can combine with other biomolecules through hydrophobic interactions, hydrogen bonds, and electrostatic interactions.…”