Force-driven DLD (f-DLD), which are driven by external forces, could also achieve the purpose of separating particles of different sizes [10]. displacement (DLD)-based microfluidic methods have been proposed to effectively individual biological [1,2,3,4] and nonbiological particles SR10067 [5]. They are passive methods in which particles flow within the fluid through a periodic array of hurdles. The separating efficiency can be improved by optimizing the geometry of the hurdles [6,7,8] and some factors of P2RY5 the viscoelastic fluid [9]. Force-driven DLD (f-DLD), which are driven by external causes, could also accomplish the purpose of separating particles of different sizes [10]. Compared to DLD methods, f-DLD methods do not require the precise design of the microstructure or extra pumps. Some external forces, such as centrifugal pressure [11], electric field pressure [12,13,14] and gravity [15,16] have been proved to generate f-DLD for the efficient separation of particles of different sizes. The motion of magnetic beads in microchannels driven by magnetic causes has been widely used in various applications for the manipulation of biological species, such as CTC sorting SR10067 [17,18,19], DNA extraction [20] and antigen detection [21]. Targets carried by magnetic beads were captured at specific sites under the combined actions of the magnetic pressure and the fluid for further detections [22]. However, using magnetic pressure to drive microbeads in a DLD system is rarely reported. In this study, we designed a novel magnetic-driven DLD (m-DLD) separating device and exhibited its overall performance. The magnetic field produced by a permanent magnet was used to drive magnetic beads to circulation through a periodic array of cylindrical hurdles. No extra actuating elements such as syringe pumps were required. The effects of forcing angle and inlet width around the separating efficiency of magnetic particles of different sizes were explored. This m-DLD device with optimal parameters was further used as a simple method for the antibody acknowledgement and separation in a mixture answer of antibodies. The trajectories of the magnetic beads transporting different antibodies were analyzed to distinguish the types of antibodies. This m-DLD separating device shows potential SR10067 as a simple and portable biosensing device for realizing and separating a mixture of multiple types of target molecules at the same time. 2. Materials and Methods 2.1. Reagents Ferroferric oxide (Fe3O4) magnetic beads (50 mg/mL) with diameters of 10 m, 20 m and 40 m were purchased from Suzhou Zhiyi Microspheres (Suzhou, China). The surface of the bead was altered with carboxyl functional groups for coupling proteins. Alpha-fetoprotein protein (AFP), mouse anti-human AFP, prostate specific antigen (PSA), mouse anti-human PSA, hepatitis B surface antigen (HBsAg) and mouse anti-human HBsAg were purchased from Zhengzhou Cell To Antibody & Antigen Biotech (Zhengzhou, China). FITC-conjugated affinipure goat anti-mouse IgG was purchased from Proteintech Group (Chicago, IL, USA). Sorbitol was purchased from Dingguo Biotechnology (Beijing, China). 4-Morpholineethanesulfonic acid hydrate (MES), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), N-hydroxysuccinimide (NHS), bovine serum albumin (BSA), and immunostaining fixative were purchased from Shanghai Yuanye Bio-Technology (Shanghai, China). 2.2. Microfluidic Chip Design and Fabrication The m-DLD chip in this study is usually 1.2 cm long to ensure that the magnetic force is large enough to drive the motion of magnetic beads, and the SR10067 number of the micropillar row is enough for a better separating efficiency. One inlet, five stores (respectively labeled as 1, 2, 3, 4 and 5 in Physique 1a) and two stages of mirrored round micropillars array are fabricated. The middle SR10067 outlet of the first stage, which is usually connected to the inlet of the second stage, is defined as the Joint (Physique 1c). At the entrance of.
Force-driven DLD (f-DLD), which are driven by external forces, could also achieve the purpose of separating particles of different sizes [10]
