National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, PR China.
College of Biomedical Engineering, Sichuan University, Chengdu 610064, PR China.
ACS Appl Bio Mater. 2024 Mar 18;7(3):1763-1777. doi: 10.1021/acsabm.3c01178. Epub 2024 Feb 20.
Encapsulation of plant polyphenols with micro-/nano-carriers for enhanced bioavailability has been well documented, but the preparation of these carriers and subsequent loading of polyphenols is a multiple process, which is generally complicated with potentially unexpected negative effects on the bioactivity of the polyphenols. Here, we reported a convenient method to assemble carrier-free polyphenol nanoparticles (NPs) based on oxidative coupling polymerization. The effectiveness was assessed with five different polyphenols including pyrocatechol (PY), catechin (CA), epigallocatechin gallate (EGCG), tannic acid (TA), and proanthocyanidin (PC). The structural characteristics of these assembled nanoparticles (PY NPs, CA NPs, EG NPs, TA NPs, and PC NPs) were systematically analyzed with dynamic light scattering (DLS), transmission electron microscopy (TEM), UV-visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR). All NPs were colloidally stable with varying NaCl concentrations from 0 to 300 mM, were acid-resistant and alkali-intolerant, and were suitable for oral administration. An array of antioxidant assays further confirmed the superior antioxidant capabilities of NPs over Trolox and polyphenol monomers, indicating that the oxidative polymerization of polyphenols did not compromise the polyphenol activity of NPs. The simulated digestion studies validated that these responsive NPs were actually gastrointestinal pH-responsive and applicable to the gastrointestinal physiological environment. The bioaccessibility assessments by using a static digestion model revealed that better results were achieved with NPs than polyphenol monomers, with TA NPs showing about 1.5-fold higher bioaccessibility than other polyphenol nanoparticles. The present study with five polyphenols demonstrated that the oxidative polymerization of polyphenols provides an effective platform to assemble various carrier-free NPs with enhanced antioxidant activity, favorable stability, and improved bioaccessibility, which could be used promisingly as a functional food ingredient in food matrices or as oral drug delivery candidates for helping to manage human health or treating various gastrointestinal disorders in both the pharmaceutical and nutritional fields.
用微/纳米载体对植物多酚进行包封以提高其生物利用度已有大量文献记载，但这些载体的制备以及随后的多酚负载是一个多步骤过程，通常会对多酚的生物活性产生潜在的意外负面影响。在这里，我们报道了一种基于氧化偶联聚合来组装无载体多酚纳米颗粒（NPs）的简便方法。我们用 5 种不同的多酚包括邻苯二酚（PY）、儿茶素（CA）、表没食子儿茶素没食子酸酯（EGCG）、单宁酸（TA）和原花青素（PC）来评估这种方法的有效性。通过动态光散射（DLS）、透射电子显微镜（TEM）、紫外-可见分光光度法和傅里叶变换红外光谱（FTIR）系统地分析了这些组装的纳米颗粒（PY NPs、CA NPs、EG NPs、TA NPs 和 PC NPs）的结构特征。所有 NPs 在 0 至 300mM 的不同 NaCl 浓度下均具有胶体稳定性，耐酸不耐碱，适合口服给药。一系列抗氧化测定进一步证实 NPs 具有优于 Trolox 和多酚单体的优越抗氧化能力，表明多酚的氧化聚合并未降低 NPs 的多酚活性。模拟消化研究验证了这些响应性 NPs 实际上是胃肠道 pH 响应的，适用于胃肠道生理环境。使用静态消化模型进行的生物可及性评估表明，与多酚单体相比，NPs 具有更好的效果，其中 TA NPs 的生物可及性比其他多酚纳米颗粒高约 1.5 倍。本研究用 5 种多酚证明了多酚的氧化聚合提供了一个有效的平台，可以组装具有增强的抗氧化活性、良好的稳定性和提高的生物可及性的各种无载体 NPs，这些 NPs 可以作为功能性食品成分用于食品基质中，或作为口服药物输送候选物，以帮助管理人类健康或治疗药物和营养领域中的各种胃肠道疾病。
