College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, North Ren Min Road No. 2999, Shanghai 201620, China.
Department of Cardiac Surgery, Zhongshan Hospital, Fudan University, Shanghai 200032, China.
Acta Biomater. 2020 Jan 1;101:436-443. doi: 10.1016/j.actbio.2019.10.035. Epub 2019 Oct 28.
Protein-templated gold nanoclusters have attracted attention in fluorescence imaging due to their simple synthesis and good biocompatibility. However, limitations still exist such as poor colloid stability and undesirable fluorescence intensity. Here we describe the self-assembly of keratin-templated gold nanoclusters via a simple and mild preparation process, including keratin-templated synthesis of gold nanoclusters (AuNCs@Keratin), silver ions modification of AuNCs@Keratin (AuNCs-Ag@Keratin), and gadolinium ions-induced aggregation of AuNCs-Ag@Keratin (AuNCs-Ag@Keratin-Gd). It was demonstrated that the AuNCs-Ag@Keratin-Gd obtained an enhanced fluorescence intensity (6.5 times that of AuNCs@Keratin), high colloid stability for more than 4 months, and good biocompatibility. Moreover, the AuNCs-Ag@Keratin-Gd holds promise in multifunctional applications such as near-infrared (NIR) fluorescence imaging, magnetic resonance (MR) imaging, and redox-responsive drug delivery, extending the applicability of fluorescent gold nanoclusters, especially in biomedical fields. STATEMENT OF SIGNIFICANCE: Assembly-induced fluorescence enhancement has been rarely reported on as it relates to the protein-templated gold nanoclusters (AuNCs). In this work, self-assembly of protein-templated AuNCs was developed for enhanced fluorescence intensity and multifunctional applications, including bioimaging and responsive drug delivery. A cysteine-rich protein, keratin, was utilized as the template to synthesize AuNCs, which underwent silver ion modification and gadolinium ion-induced aggregation. The silver modification of the keratin-templated AuNCs facilitated the formation of a dense aggregate after gadolinium ion-induced assembly, thus generating an enhanced fluorescence intensity. Such a mechanism was confirmed by fluorescence correlation spectroscopy analysis. We believe that this work will extend the applicability of the fluorescent gold nanoclusters, especially in biomedical fields, and provided an effective approach for the mechanism analysis of the assembly-induced fluorescence enhancement via fluorescence correlation spectroscopy.
基于简单的合成方法和良好的生物相容性，蛋白模板金纳米团簇在荧光成像领域受到了广泛关注。然而，其仍存在胶体稳定性差和荧光强度不理想等局限性。本研究通过一种简单温和的制备工艺，描述了角蛋白模板金纳米团簇的自组装过程，包括角蛋白模板合成金纳米团簇（AuNCs@Keratin）、AuNCs@Keratin 的银离子修饰（AuNCs-Ag@Keratin）以及 AuNCs-Ag@Keratin 的镓离子诱导聚集（AuNCs-Ag@Keratin-Gd）。结果表明，所制备的 AuNCs-Ag@Keratin-Gd 具有增强的荧光强度（是 AuNCs@Keratin 的 6.5 倍）、超过 4 个月的高胶体稳定性和良好的生物相容性。此外，AuNCs-Ag@Keratin-Gd 在多功能应用方面具有广阔的应用前景，如近红外（NIR）荧光成像、磁共振（MR）成像和氧化还原响应性药物递送，扩展了荧光金纳米团簇的适用性，特别是在生物医学领域。
与蛋白模板金纳米团簇（AuNCs）相关的组装诱导荧光增强现象鲜有报道。在这项工作中，开发了基于蛋白模板的 AuNCs 自组装方法，以提高荧光强度并实现多功能应用，包括生物成像和响应性药物递送。角蛋白作为模板合成 AuNCs，然后进行银离子修饰和镓离子诱导聚集。角蛋白模板 AuNCs 的银离子修饰促进了镓离子诱导组装后致密聚集体的形成，从而产生增强的荧光强度。荧光相关光谱分析证实了这一机制。我们相信，这项工作将扩展荧光金纳米团簇的适用性，特别是在生物医学领域，并为通过荧光相关光谱分析研究组装诱导荧光增强的机制提供了一种有效的方法。
