New Design forDetection Cell Applied in Magnetic Particle‐Based Electrochemiluminescence Assays

Abstract

Electrochemiluminescence (ECL) is a powerful technique for sensitive detecting a variety of analytes such as alkylamine, proteins, etc. [1][2][3]. To improve the performance of ECL systems such as sensitivity and stability, much effort has been taken by using auxiliary materials (e.g. nanomaterials [4]). Magnetic particles (MPs) belong to one kind of nanomaterials with interesting magnetic properties and can be employed in many ECL applications to achieve analyte concentration and in-situ electrode regeneration [5]. With the emergency of graphene, MPs have been endowing with much more positive functionality [6]. Many efforts have been devoted to introduction of MPs into ECL assays for sensitive analyte detection [7,8]. Despite of the efforts, scarce report has been presented on systematic study about the MPs effects on the ECL efficiency.As an important branch of this field, the detection cell design is the prerequisite to further development the MPs based-ECL strategy. However, in many present ECL instruments (e.g. the CE-ECL system made by Xian Remex Analytic Instrument Co., Ltd., China), the photomultiplier tubes (PMT) was under the working electrode (WE) side (see Figure 1A), this configuration was convenient for traditional ECL assays but difficult to realize the MPs-based ECL ones because the luminescence would be possibly hindered by the external magnet that also was placed under the electrode side. Meanwhile, for the previous cell used for the instrument in which the PMT was above the WE side, the impurity precipitates could deposit on the electrode surface due to the gravity effect and bring negative effects on the detection results. Moreover, the electrode was not convenient for mounting and dismounting as well as the physical cleaning of the WE (Elecsys Service Manual, p. 70). The existing problems mentioned above have inspired us to develop a new design configuration ( Figure 1B) of detection cell that is suitable for convenient and efficient MPs-based ECL detection assays. Based on the cell, effects of different MPs with and without graphene on ECL efficiency were studied systematically.The configuration and actual image of the cell was designed as shown in Figure 1C and 1D: the whole cell body is cylindrical (height 2.8 cm, diameter 3.9 cm). A rectangular surface on one side of the cell was cut out along the y-axis direction. The sample reservoir 1, which is also cylindrical (height 1.0 cm, diameter 0.3 cm), is set at the lower half of the inside cell. The bottom of the sample reservoir is covered with a circular quartz glass and O-ring seal, via which the effective light collection can be ensured and the solution leakage can be avoided. Both the accommodating holes of the reference electrode 7 and the counter electrode 8 are connected with the sample reservoir 1. The two accommodating holes cross the bottom of sample reservoir 1 at acute angles (458). The accommodating groove of WE (labeled as 2) is connected with top side of the sample reservoir 1. The sheet WE 9 is of the same size as the accommo...