Lucas Lonnie J, Chesler Jennine N, Yoon Jeong-Yeol
Department of Agricultural and Biosystems Engineering, The University of Arizona, Tucson, AZ 85721-0038, USA.
Biosens Bioelectron. 2007 Dec 15;23(5):675-81. doi: 10.1016/j.bios.2007.08.004. Epub 2007 Aug 11.
Double detection of microsphere light scattering and quantum dot emission was demonstrated for lab-on-a-chip immunoassay without using stationary support. We conjugated quantum dots (QDs) onto microspheres to enable multiplex assays as well as to enhance the limit of detection (LOD). We named this configuration "nano-on-micro" or "NOM". Upon radiation with UV light (380nm), a stronger light scattering signal is observed with NOMs than QDs or microspheres alone. Additionally, NOMs are easier to handle than QDs. Since QDs also provide fluorescent emission, we are able to utilize an increase in light scattering for detecting antigen-antibody reaction and a decrease in QD emission to identify which antibody (or antigen) is present. Two types of NOM combinations were used. One batch of microspheres was coated with QDs emitting at 655 nm and mouse IgG (mIgG); the other with QDs emitting at 605 nm and bovine serum albumin (BSA). A mixture of these two NOMs was used to identify either anti-mIgG or anti-BSA. NOM particles and target solutions were mixed in a microfluidic device (using highly carboxylated microspheres as previously demonstrated by our group) and on-chip detection was performed using proximity optical fibers. Forward light scattering at 380 nm was collected. With the positive target, the scattering signal was increased. The LOD was as low as 50 ng ml(-1) (330 pM) with p<0.05. Fluorescent emission (655 or 605 nm) was simultaneously collected. With the positive target, the emission signal was attenuated. Therefore, we were able to detect two different antibodies simultaneously with two different detection protocols. We believe this NOM bioassay has the ability to screen for and detect multiple antibodies with minimal sample processing and handling (one-step lab-on-a-chip immunoassay).
在不使用固定支撑物的情况下，实现了用于芯片实验室免疫分析的微球光散射和量子点发射的双重检测。我们将量子点（QD）偶联到微球上，以实现多重分析并提高检测限（LOD）。我们将这种配置命名为“纳米在微球上”或“NOM”。在用紫外线（380nm）照射时，与单独的量子点或微球相比，NOM显示出更强的光散射信号。此外，NOM比量子点更易于处理。由于量子点也能提供荧光发射，我们能够利用光散射的增加来检测抗原-抗体反应，并利用量子点发射的减少来识别存在哪种抗体（或抗原）。使用了两种类型的NOM组合。一批微球包被发射655nm光的量子点和小鼠IgG（mIgG）；另一批包被发射605nm光的量子点和牛血清白蛋白（BSA）。使用这两种NOM的混合物来识别抗mIgG或抗BSA。将NOM颗粒和靶溶液在微流控装置中混合（使用我们小组先前证明的高度羧化微球），并使用近场光纤进行芯片上检测。收集380nm处的前向光散射。有阳性靶标时，散射信号增加。检测限低至50 ng ml(-1)（330 pM），p<0.05。同时收集荧光发射（655或605nm）。有阳性靶标时，发射信号减弱。因此，我们能够通过两种不同的检测方案同时检测两种不同的抗体。我们相信这种NOM生物分析方法有能力以最少的样品处理和操作（一步式芯片实验室免疫分析）来筛选和检测多种抗体。
