Upconverting phosphors (UCPs) convert multiple low energy photons into higher energy emission via the process of photon upconversion and offer an attractive alternative to organic fluorophores for use as luminescent probes. Examples of biosensors utilizing the apparent energy transfer of UCPs and nanophosphors (UCNPs) with biomolecules have started to appear in the literature but very few exploit the covalent anchoring of the biomolecule to the surface of the UCP to improve the sensitivity of the systems. Here, we demonstrate a robust and versatile method for the covalent attachment of biomolecules to the surface of a variety of UCPs and UCNPs in which the UCPs were capped with functionalized silica in order to provide a surface to covalently conjugate biomolecules with surface-accessible cysteines. Variants of BM3Heme, cytochrome C, glucose oxidase, and glutathione reductase were then attached via maleimide-thiol coupling. BM3Heme, glucose oxidase, and glutathione reductase were shown to retain their activity when coupled to the UCPs potentially opening up opportunities for biosensing applications.

上转换荧光粉 (UCP) 通过光子上转换过程将多个低能光子转换为更高能量的发射，并为用作发光探针的有机荧光团提供了一种有吸引力的替代品。利用 UCP 和纳米磷光体 (UCNP) 与生物分子的表观能量转移的生物传感器的例子已经开始出现在文献中，但很少有人利用生物分子与 UCP 表面的共价锚定来提高系统的灵敏度。在这里，我们展示了一种将生物分子共价附着到各种 UCP 和 UCNP 表面的稳健且通用的方法，其中 UCP 用功能化二氧化硅封端，以便为生物分子与表面可及的半胱氨酸共价结合提供表面。然后通过马来酰亚胺-硫醇偶联连接 BM3Heme、细胞色素 C、葡萄糖氧化酶和谷胱甘肽还原酶的变体。 BM3血红素、葡萄糖氧化酶和谷胱甘肽还原酶在与 UCP 偶联时被证明可以保留其活性，这可能为生物传感应用开辟机会。