Department of Chemistry , University of Turku , FI-20014 Turku , Finland.
Doctoral Programme in Physical and Chemical Sciences , University of Turku Graduate School (UTUGS) , FI-20014 Turku , Finland.
Langmuir. 2018 Jul 3;34(26):7759-7766. doi: 10.1021/acs.langmuir.8b00869. Epub 2018 Jun 22.
Aqueous solutions are the basis for most biomedical assays, but they quench the upconversion luminescence significantly. Surface modifications of upconverting nanoparticles are vital for shielding the obtained luminescence. Modifications also provide new possibilities for further use by introducing attaching sites for biomolecule conjugation. We demonstrate the use of a layer-by-layer surface modification method combining varying lengths of negatively charged polyelectrolytes with positive neodymium ions in coating the upconverting NaYF:Yb,Er nanoparticles. We confirmed the formation of the bilayers and investigated the surface properties with Fourier transform infrared and reflectance spectroscopy, thermal analysis, and ζ-potential measurements. The effect of the coating on the upconversion luminescence properties was characterized, and the bilayers with the highest improvement in emission intensity were identified. In addition, studies for the nanoparticle and surface stability were carried out in aqueous environments. It was observed that the bilayers were able to shield the materials' luminescence from quenching also in the presence of phosphate buffer that is currently considered the most disruptive environment for the nanoparticles.
水溶液是大多数生物医学分析的基础，但它们会显著猝灭上转换发光。上转换纳米粒子的表面修饰对于屏蔽所获得的发光至关重要。修饰还通过引入用于生物分子缀合的附着位点，为进一步的应用提供了新的可能性。我们展示了一种逐层表面修饰方法，该方法结合了不同长度的带负电荷的聚电解质与正钕离子，用于包覆上转换的 NaYF:Yb,Er 纳米粒子。我们证实了双层的形成，并通过傅里叶变换红外和反射光谱、热分析和 ζ-电位测量研究了表面性质。对涂层对上转换发光性能的影响进行了表征，并确定了发射强度提高最大的双层。此外，还在水相环境中进行了纳米粒子和表面稳定性的研究。观察到在存在当前被认为对纳米粒子最具破坏性的磷酸盐缓冲液的情况下，双层能够屏蔽材料的发光，防止其猝灭。
