An integrated lab-on-a-disc for automated cell-based allergen screening bioassays.

We have utilized various valving scheme to leverage purely rotation-regulated flow control to enable comprehensive cell-based bioassays (CBBs) on centrifuge-based lab-on-a-disc (LOAD). A LOAD has been developed to examine allergic degranulation from live basophils for allergens screening for the first time, which can also be adjusted to suit a wide range of CBBs. In this system, controlled allergic reaction together with mediator separation from basophils using siphon valving and centrifugal sedimentation are realized inside microstructured network. The entire degranulation analysis process including on-demand release of samples, reaction and degranulation, allergic mediator separation and detection is executed in an automatic sequence within a single run. To validate our cell-based approach, detection of degranulation mediated by known secretagagues, ionomycin or chemotatic peptide formyl-methionine-leucine-pheylalanine (fMLP), is first demonstrated. Further experiments using real allergens house dust mite protein (Der p1) and its corresponding human serum IgE also show positive results. The overall efficiency of the assay is 80.6%, which is comparable to other conventional methods. With 4 identical units on a disc running in a parallel format, the device offers the possibility of single-step, multiplexed allergens screening. The device is capable of reporting a result within 30 min. It has many desirable merits including fast and multiplexed analysis, low cost, single-step operation, minimal sample volume, less discomfort and most importantly increased safety as patients are no longer susceptible to possible anaphylactic shock reactions induced by the common skin-prick-test. The flexibility of the flow control within the device makes it suitable to a wide range of CBBs.