Wiederoder M S, Smith S, Madzivhandila P, Mager D, Moodley K, DeVoe D L, Land K J
Council for Scientific and Industrial Research, Pretoria, South Africa.
Karlsruhe Institute of Technology, Karlsruhe, Germany.
Biomicrofluidics. 2017 Sep 12;11(5):054101. doi: 10.1063/1.5002644. eCollection 2017 Sep.
The presented work demonstrates novel functionalities of hybrid paper-polymer centrifugal devices for assay performance enhancement that leverage the advantages of both paper-based and centrifugal microfluidic platforms. The fluid flow is manipulated by balancing the capillary force of paper inserts with the centrifugal force generated by disc rotation to enhance the signal of a colorimetric lateral flow immunoassay for pathogenic . Low-cost centrifugation for pre-concentration of bacteria was demonstrated by sample sedimentation at high rotational speeds before supernatant removal by a paper insert via capillary force after deceleration. The live bacteria capture efficiency of the device was similar to a commercial centrifuge. This pre-concentrated sample when combined with gold nanoparticle immunoconjugate probes resulted in a detection limit that is 10× lower than a non-concentrated sample for a lateral flow immunoassay. Signal enhancement was also demonstrated through rotational speed variation to prevent the flow for on-device incubation and to reduce the flow rate, thus increasing the sample residence time for the improved capture of gold nanoparticle-bacteria complexes in an integrated paper microfluidic assay. Finally, multiple sequential steps including sample pre-concentration, filtration, incubation, target capture by an integrated paper microfluidic assay, silver enhancement and quenching, and index matching were completed within a single device. The detection limit was 10 colony forming units per ml, a 100× improvement over a similar paper-based lateral flow assay. The techniques utilize the advantages of paper-based microfluidic devices, while facilitating additional functionalities with a centrifugal microfluidic platform for detection performance enhancement in a low-cost, automated platform amenable to point-of-care environments.
所展示的工作展示了用于增强检测性能的混合纸聚合物离心装置的新功能，该装置利用了基于纸的和离心微流控平台的优势。通过平衡纸插入物的毛细作用力与圆盘旋转产生的离心力来操纵流体流动，以增强用于病原体的比色侧向流动免疫分析的信号。通过在高速旋转时进行样品沉降，然后在减速后通过纸插入物利用毛细作用力去除上清液，证明了用于细菌预浓缩的低成本离心方法。该装置对活细菌的捕获效率与商用离心机相似。当这种预浓缩样品与金纳米颗粒免疫共轭探针结合时，对于侧向流动免疫分析，其检测限比未浓缩样品低10倍。还通过改变转速来证明信号增强，以防止流动用于装置上的孵育并降低流速，从而增加样品停留时间，以在集成纸微流控分析中更好地捕获金纳米颗粒 - 细菌复合物。最后，在单个装置内完成了多个连续步骤，包括样品预浓缩、过滤、孵育、通过集成纸微流控分析进行目标捕获、银增强和淬灭以及折射率匹配。检测限为每毫升10个菌落形成单位，比类似的基于纸的侧向流动分析提高了100倍。这些技术利用了基于纸的微流控装置的优势，同时通过离心微流控平台促进了额外的功能，以在适用于即时检测环境的低成本、自动化平台中提高检测性能。
