Gold nanorods (GNR) and gold nanospheres (GNS) of different surface charges; neutral -poly ethylene glycol (PEG), negatively charged poly acrylic acid (PAA), and positively charged poly allyl amine hydrochloride (PAH), were synthesized and characterized, and their colloidal stability was investigated using UV-Vis absorption spectra and zeta potential measurements. Gold nanoparticles (GNP) were loaded at different concentrations (from 1.0 to 6.0 nM) into two hydrogels prepared in water; 18% w/v Poloxamer 407 and 1.5% w/v hydroxypropyl methylcellulose (HPMC). The GNP hydrogels were characterized in terms of GNP colloidal stability, and the rheological properties of the GNP hydrogels. GNP loaded into HPMC hydrogel demonstrated poor stability and exhibited separation into two layers. On the contrary, colloidal stability of the GNP was preserved upon loading into Poloxamer 407 hydrogel. The rheology study demonstrates that Poloxamer 407 hydrogel was able to accommodate GNR or GNS at concentrations lower than 6.0 nM with no apparent change in the measured rheology parameters. PAH-coated GNP caused the largest decrease in the low shear rate viscosity values. The elastic modulus was higher than the viscous modulus at the entire concentration range and the values of the phase shift angle did not exceed 10 degrees indicating prevail elastic property. As a conclusion, Poloxamer 407 hydrogel is a good candidate as a topical vehicle for both GNR and GNS at concentrations lower than 6.0 nM.

中文翻译：

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金纳米粒子负载聚合物水凝胶的胶体稳定性和流变特性：纳米粒子形状、表面改性和浓度的影响

不同表面电荷的金纳米棒（GNR）和金纳米球（GNS）；合成并表征了中性聚乙二醇 (PEG)、带负电荷的聚丙烯酸 (PAA) 和带正电荷的聚烯丙胺盐酸盐 (PAH)，并使用紫外-可见吸收光谱和 zeta 电位测量研究了它们的胶体稳定性. 将不同浓度（从 1.0 到 6.0 nM）的金纳米粒子 (GNP) 装入两种在水中制备的水凝胶中；18% w/v 泊洛沙姆 407 和 1.5% w/v 羟丙基甲基纤维素 (HPMC)。GNP 水凝胶的特征在于 GNP 胶体稳定性和 GNP 水凝胶的流变特性。加载到 HPMC 水凝胶中的 GNP 表现出较差的稳定性并表现出分成两层。相反，GNP 的胶体稳定性在装入泊洛沙姆 407 水凝胶后得以保留。流变学研究表明，泊洛沙姆 407 水凝胶能够适应浓度低于 6.0 nM 的 GNR 或 GNS，而测得的流变学参数没有明显变化。PAH 包覆的 GNP 导致低剪切速率粘度值的最大下降。在整个浓度范围内，弹性模量高于粘性模量，相移角的值不超过 10 度，表明弹性性能占优势。总之，泊洛沙姆 407 水凝胶是一个很好的候选者，可作为 GNR 和 GNS 浓度低于 6.0 nM 的局部载体。0 nM，测得的流变参数没有明显变化。PAH 包覆的 GNP 导致低剪切速率粘度值的最大下降。在整个浓度范围内，弹性模量高于粘性模量，相移角的值不超过 10 度，表明弹性性能占优势。总之，泊洛沙姆 407 水凝胶是一个很好的候选者，可作为 GNR 和 GNS 浓度低于 6.0 nM 的局部载体。0 nM，测得的流变参数没有明显变化。PAH 包覆的 GNP 导致低剪切速率粘度值的最大下降。在整个浓度范围内，弹性模量高于粘性模量，相移角的值不超过 10 度，表明弹性性能占优势。总之，泊洛沙姆 407 水凝胶是一个很好的候选者，可作为 GNR 和 GNS 浓度低于 6.0 nM 的局部载体。