Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
J Colloid Interface Sci. 2024 Jan 15;654(Pt B):967-978. doi: 10.1016/j.jcis.2023.10.119. Epub 2023 Oct 24.
In this study, an efficient synthetic strategy and potential route to obtain a photo-reactive silver-containing cytosine-functionalized polypropylene glycol polymer (Ag-Cy-PPG) was developed by combining a hydrophilic oligomeric polypropylene glycol (PPG) backbone with dual pH-sensitive/photo-reactive cytosine-silver-cytosine (Cy-Ag-Cy) linkages. The resulting photo-responsive Ag-Cy-PPG holds great promise as a multifunctional biomedical material that generates spherical-like nanogels in water; the nanogels exhibit high antibacterial activity and thus may significantly enhance the efficacy of antibacterial treatment. Due to the formation of photo-dimerized Cy-Ag-Cy cross-linkages after UV irradiation, Ag-Cy-PPG converts into water-soluble cross-linked nanogels that possess a series of interesting chemical and physical properties, such as intense and stable fluorescence behavior, highly sensitive pH-responsive characteristics, on/off switchable phase transition behavior, and well-controlled release of silver ions (Ag) in mildly acidic aqueous solution. Importantly, antibacterial tests clearly demonstrated that irradiated Ag-Cy-PPG nanogels exhibited strong antibacterial activity at low doses (MIC values of < 50 μg/mL) against gram-positive and gram-negative bacterial pathogens, whereas non-irradiated Ag-Cy-PPG nanogels did not inhibit the viability of bacterial pathogens. These results indicate that irradiated Ag-Cy-PPG nanogels undergo a highly sensitive structural change in the bacterial microenvironment due to their relatively unstable π-conjugated structures (compared to non-irradiated nanogels); this change results in a rapid structural response that promotes intracellular release of Ag and induces potent antibacterial ability. Overall, this newly created metallo-supramolecular system may potentially provide an efficient route to dramatically enhance the therapeutic effectiveness of antibacterial treatments.
在这项研究中，通过将亲水性寡聚丙二醇（PPG）主链与双 pH 敏感/光反应胞嘧啶-银-胞嘧啶（Cy-Ag-Cy）键结合，开发了一种高效的合成策略和潜在途径来获得光反应性含银胞嘧啶功能化聚丙二醇聚合物（Ag-Cy-PPG）。所得光响应性 Ag-Cy-PPG 有望成为一种多功能生物医学材料，可在水中生成类似球形的纳米凝胶；纳米凝胶表现出高抗菌活性，因此可能显著增强抗菌治疗的效果。由于在 UV 照射后形成光二聚化的 Cy-Ag-Cy 交联，Ag-Cy-PPG 转化为水溶性交联纳米凝胶，具有一系列有趣的化学和物理性质，例如强烈和稳定的荧光行为、高度敏感的 pH 响应特性、开/关可切换的相转变行为以及在温和酸性水溶液中银离子（Ag）的良好控制释放。重要的是，抗菌测试清楚地表明，照射的 Ag-Cy-PPG 纳米凝胶在低剂量（MIC 值<50μg/mL）下对革兰氏阳性和革兰氏阴性细菌病原体表现出强烈的抗菌活性，而未照射的 Ag-Cy-PPG 纳米凝胶不会抑制细菌病原体的活力。这些结果表明，照射的 Ag-Cy-PPG 纳米凝胶由于其相对不稳定的π共轭结构（与未照射的纳米凝胶相比），在细菌微环境中经历了高度敏感的结构变化；这种变化导致快速的结构响应，促进细胞内 Ag 的释放，并诱导强大的抗菌能力。总体而言，这种新创建的金属超分子系统可能为显著增强抗菌治疗的疗效提供一条有效途径。
