Department of Chemistry, State University of New York at Potsdam, Potsdam, NY 13676, USA.
Biomaterials. 2011 Apr;32(12):3312-21. doi: 10.1016/j.biomaterials.2010.12.064.
In view of the prospective applications of polyamine coatings in functional gold nanoparticles for use as carriers in gene delivery systems, in tissue repair and as bactericidal and virucidal non-toxic vehicle, we have investigated the interactions of poly-l-lysine (PLL) with gold nanoparticles (AuNP). Since direct binding of PLL to AuNP is not strong at neutral pH, we have focused on PLL interactions with carboxylated self-assembled monolayers (SAM) on AuNP, such as the citrate-capped AuNP. The double-shell nanoparticles AuNP@Cit/PLL thus produced do not contain any toxic thiols. We have observed strong electrostatic interactions between polycationic chains of PLL and AuNP@Cit in weakly acidic to weakly alkaline solutions (pH 5-9), as evidenced by the bathochromic shift of the local surface plasmon (SP) band and strong increase in resonance elastic light scattering (RELS) intensity. The stoichiometry of interactions evaluated on the basis of RELS data indicates on a hyper-Langmuirian type of interactions with stoichiometric coefficient n = 1.35 (PLL : AuNP@Cit). From the RELS titration data, a shift of the deprotonation constant for the bound PLL has been determined (pK(a) = 11.6 for the bound PLL vs. 10.48 for the free PLL). The deprotonation of PLL leads to AuNP aggregate disassembly, evidenced by sharp RELS decline and hypsochromic shift of SP band. We have found that under these conditions, a residual aggregation due to the interparticle interactions between β-sheets of PLL overcoat become predominant. The molecular dynamics simulations indicate that multiple hydrogen bonds can also be formed between the PLL linker and the shell molecules of AuNP@Cit. The double-shell nanoparticles, AuNP@Cit/PLL, have been shown to attract DNA molecules using highly sensitive RELS measurements presenting the proof-of-concept for the suitability of this non-toxic nanostructured material for gene delivery applications. The advantage of the proposed material is no toxicity related to the ligand release in gene delivery processes in contrast to the thiol-functionalized AuNP.
鉴于多胺涂层在功能性金纳米粒子中的应用前景，这些纳米粒子可用作基因传递系统中的载体、组织修复材料以及杀菌和杀病毒的无毒载体，我们研究了聚-L-赖氨酸（PLL）与金纳米粒子（AuNP）的相互作用。由于在中性 pH 下 PLL 与 AuNP 的直接结合不牢固，我们专注于 PLL 与 AuNP 上的羧基自组装单层（SAM）的相互作用，例如柠檬酸封端的 AuNP。由此产生的 AuNP@Cit/PLL 双层纳米粒子不含任何有毒的硫醇。我们观察到带正电荷的 PLL 与 AuNP@Cit 在弱酸性到弱碱性溶液（pH 5-9）之间存在强烈的静电相互作用，这表现为局域表面等离子体（SP）带的红移和共振弹性光散射（RELS）强度的强烈增加。根据 RELS 数据评估的相互作用的化学计量表明，在超朗缪尔型相互作用中，化学计量系数 n=1.35（PLL：AuNP@Cit）。从 RELS 滴定数据中，确定了结合 PLL 的去质子化常数的变化（结合 PLL 的 pK(a)=11.6 与游离 PLL 的 pK(a)=10.48 相比）。PLL 的去质子化导致 AuNP 聚集物的解体，这表现为 RELS 急剧下降和 SP 带的蓝移。我们发现，在这些条件下，由于 PLL 覆盖层中β-折叠之间的颗粒间相互作用，会出现残留的聚集。分子动力学模拟表明，PLL 连接子与 AuNP@Cit 的壳分子之间也可以形成多个氢键。通过使用高度灵敏的 RELS 测量，已经证明双层纳米粒子 AuNP@Cit/PLL 可以吸引 DNA 分子，这为这种无毒纳米结构材料在基因传递应用中的适用性提供了概念验证。与硫醇功能化的 AuNP 相比，该材料的优点在于在基因传递过程中没有与配体释放相关的毒性。
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