A Smart Shipping Incubator for Biodosimetry Logistics in Radiation Countermeasure Operations

Mass nuclear catastrophe is a serious concern for society at large when considering the rising threat of terrorism and the risks associated with harnessing nuclear energy. In the case of a mass nuclear/radiological event that requires hundreds of thousands of individuals to be assessed for radiation exposure, a rapid biodosimetry triage tool is crucial [1]. The Cytokinesis Block Micronucleus Assay (CBMN) is a promising cytogenetic biodosimetry assay for triage [2]; however, it requires shipping samples to a central laboratory (1-3 days) followed by a lengthy cell culture process (~3 days) before the first dose estimate can be available. The total ~ 1 week response time is too long for effective medical care intervention. A shipping incubator could cut the response time in half (~3 days) by culturing samples in transit; however, possible shipping delays beyond 2 days without the addition of a necessary reagent (Cyto-B) would ruin the integrity of the samples—for accurate CBMN assay endpoint observation, Cyto-B must be added within a 24-44 hour window after sample culture is initiated. Here, we propose a “Smart” Shipping Incubator (SSI) that can add Cyto-B while samples are in transit through a centrifugal system equipped with microfluidic capillary valve caps. The custom centrifugal system was constructed with CNC machined and 3D printed plastic parts, controlled by a custom printed circuit board (PBC) microcontroller, and housed inside a commercial shipping incubator (iQ5 from MicroQ Technologies). Teflon-coated, pre-pulled glass micropipettes (FivePhoton BioChemicals) were used as microfluidic capillary valve caps. Release of Cyto-B was characterized by a desktop centrifugal system at different tip sizes and relative centrifugal forces (RCFs). A theoretical model of Cyto-B release was also deduced to aid the optimization of the process. The CBMN assay was conducted both in the SSI with centrifugal Cyto-B release and in a standard CO2 incubator with manual addition of Cyto-B as the control. The expected mechanical shock during shipment was measured to be less than 25g. Optimal Cyto-B release was found to be at 35g RCF with a Teflon-coated 40 µm tip. Similar CBMN dose curves of micronuclei per binucleated cells (MN/BN) vs. exposed radiation (Gy) were produced for samples assessed conventionally and with the SSI. The similarities between the two methods suggest that centrifugation does not significantly affect the CBMN assay.