We describe a material that allows for high spatial resolution pH mapping through tissue using X-ray excited luminescence chemical imaging (XELCI). This is especially useful for detecting implant associated infection and elucidating how the local biochemical environment changes during infection and treatment. To acquire one pixel in the image, a focused X-ray beam irradiates a small region of scintillators coated on the implant and the X-ray excited optical luminescence spectrum is modulated by indicator dyes to provide a chemically sensitive measurement with low background. Scanning the X-ray beam across the implant surface generates high spatial resolution chemical measurements. Two associated challenges are 1) to make robust sensors that can be implanted in tissue to measure local chemical concentrations and specifically for metal orthopedic implants, and 2) to conformally coat the implant surface with scintillators and pH indicator dyes in order to make measurements over a large area. Previously, we have physically pressed or glued a pH-sensitive hydrogel sensor to the surface of an implant, but this is impractical for imaging over large irregular device areas such as an orthopedic plate with holes and edges. Herein we describe a chemically sensitive and biocompatible XELI sensor material containing scintillator particles (Gd₂O₂S:Eu) and a pH sensitive hydrogel coating using a roughened epoxy coating. A two-part commercial grade epoxy film was tested and found to make the coating of pH sensitive layer adhere better to the titanium surface. Sugar and salt particles were added to the surface of the epoxy as it cured to create a roughened surface and increase surface area. On this roughened surface, a secondary layer of diacrylated polyethylene glycol (PEG) hydrogel, containing a pH sensitive dye, was polymerized. This layer was found to adhere well to the epoxy-coated implant unlike other previously tested polymer surfaces which delaminated when exposed to water or humidity. The focused X-ray beam enabled 0.5 mm spatial resolution through 1 cm thick tissue. The pH sensor coated orthopedic plate was imaged with XELCI through tissue with different pH to acquire a calibration curve. The plates were also imaged through tissue with low pH region from a Staphylococcus aureus biofilm grown on one section. These studies demonstrate the use of pH sensor coated orthopedic plates for mapping the surface pH through tissue during biofilm formation using XELCI.

中文翻译：

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带有X射线闪烁器和pH指示剂的整形外科板的保形涂层，用于通过组织进行X射线激发发光化学成像。

我们描述了一种材料，该材料允许使用X射线激发发光化学成像（XELCI）通过组织进行高空间分辨率的pH映射。这对于检测植入物相关感染以及阐明感染和治疗过程中局部生化环境的变化特别有用。为了获取图像中的一个像素，聚焦的X射线束会照射覆盖在植入物上的闪烁体的一小部分，并且X射线激发的光致发光光谱会被指示剂染料调制，从而提供低背景化学敏感的测量结果。跨植入物表面扫描X射线束可产生高空间分辨率的化学测量值。与之相关的两个挑战是：1）制造坚固的传感器，可以将其植入组织中以测量局部化学浓度，特别是金属整形外科植入物； 2）用闪烁体和pH指示剂染料适形地覆盖植入物表面，以便在大面积。以前，我们已经将pH敏感的水凝胶传感器物理压制或粘合到了植入物的表面，但这对于在较大的不规则设备区域（例如带有孔和边缘的矫形板）上成像是不切实际的。本文中，我们描述了一种具有闪烁体颗粒（Gd）的化学敏感且生物相容的XELI传感器材料 我们已经将pH敏感的水凝胶传感器物理地压在或粘合到了植入物的表面上，但这对于在较大的不规则设备区域（例如带有孔和边缘的矫形板）上成像是不切实际的。本文中，我们描述了一种具有闪烁体颗粒（Gd）的化学敏感且生物相容的XELI传感器材料 我们已经将pH敏感的水凝胶传感器物理地压在或粘合到了植入物的表面上，但这对于在较大的不规则设备区域（例如带有孔和边缘的矫形板）上成像是不切实际的。本文中，我们描述了一种具有闪烁体颗粒（Gd）的化学敏感且生物相容的XELI传感器材料₂ O ₂S：Eu）和使用粗糙的环氧涂层的pH敏感水凝胶涂层。测试了由两部分组成的商业级环氧树脂膜，发现该膜能使pH敏感层的涂层更好地粘附到钛表面。糖和盐颗粒在固化时被添加到环氧树脂的表面，以形成粗糙的表面并增加表面积。在该粗糙化的表面上，聚合了含有pH敏感染料的二丙烯酸聚乙二醇（PEG）水凝胶第二层。发现该层可以很好地粘附到环氧树脂涂层的植入物上，这与其他先前测试过的聚合物表面不同，后者在暴露于水或湿气时会分层。聚焦的X射线束可通过1厘米厚的组织实现0.5毫米的空间分辨率。用XELCI通过具有不同pH值的组织对涂有pH传感器的矫形板进行XELCI成像，以获取校准曲线。还通过低pH区域的组织对板进行成像，该组织来自在一个切片上生长的金黄色葡萄球菌生物膜。这些研究表明，使用XELCI在生物膜形成过程中使用pH传感器涂覆的矫形板来绘制组织表面的pH值。