Many therapeutic drugs require monitoring of their concentration in blood followed by dose adjustments in order to ensure efficacy while minimizing adverse effects. It would be highly desirable to perform such measurements rapidly and with reduced sample volumes to support point-of-care testing. Here, we demonstrate that the concentration of small therapeutics can be determined in whole blood within paper-like membranes using Fluorescence Polarization Immunoassay (FPIA). Different types of paper-like materials such as glass microfibers, cellulose and filter paper were investigated for artefacts such as scattering or autofluorescence. Accurate determination of the fluorescence polarization of red-emitting fluorophores at sub-nanomolar concentrations was feasible within glass fiber membranes. This enabled the development of a competitive immunoassay for the quantification of the antibiotic tobramycin using only 1 μL of plasma in glass fiber micro-chambers. Furthermore, the same membrane was used for transversal separation of blood cells followed by accurate FPIA read-out at the bottom part of the micro-chamber. For quantification of tobramycin, 1 μL of whole blood was incubated with the immunoassay reagents during only 3 min before deposition in the micro-chamber and analysis. Within the therapeutic window, coefficients of variation were around 20% and recoveries between 80 and 105%. Owing to the simplified procedure requiring no centrifugation, the reduced blood sample volume and the rapid analysis time, we envision that this novel method supports the performance of therapeutic drug monitoring directly at the point of care.

许多治疗药物需要监测它们在血液中的浓度，然后调整剂量，以确保疗效，同时尽量减少副作用。非常希望快速执行此类测量并减少样本量以支持即时测试。在这里，我们证明可以使用荧光偏振免疫测定法 (FPIA) 在纸状膜内的全血中确定小量治疗剂的浓度。研究了不同类型的纸状材料，如玻璃微纤维、纤维素和滤纸，以寻找散射或自发荧光等伪影。在玻璃纤维膜内准确测定亚纳摩尔浓度的红色发射荧光团的荧光偏振是可行的。这使得开发一种竞争性免疫测定法能够在玻璃纤维微室中仅使用 1 μL 血浆对抗生素妥布霉素进行定量。此外，相同的膜用于血细胞的横向分离，然后在微室底部进行准确的 FPIA 读数。对于妥布霉素的定量，1 μL 全血与免疫测定试剂一起孵育仅 3 分钟，然后沉积在微室中并进行分析。在治疗窗口内，变异系数约为 20%，回收率在 80% 到 105% 之间。由于不需要离心的简化程序、减少的血液样本量和快速的分析时间，我们设想这种新方法支持直接在护理点进行治疗药物监测。