Objective Method for Presumptive Field-Testing of Illicit Drug Possession Using Centrifugal Microdevices and Smartphone Analysis.

Current colorimetric presumptive identification of illicit drugs for determining illegal possession of controlled substances by law enforcement relies solely on the subjective interpretation of color change using drug- or class-specific reactions. Here, we describe the use of inexpensive polyester-toner, rotation-driven microfluidic devices with a smartphone as a potential alternative for current presumptive colorimetric field-testing of illicit drugs, allowing for an objective and user-friendly image analysis technique for detection. The centrifugal microfluidic platform accommodates simultaneous presumptive testing of material from a single input to multiple reaction chambers, enabling rapid screening. Hue and saturation image analysis parameters are used to define threshold values for the detection of cocaine and methamphetamine as proof-of-principle with 0.25 and 0.75 mg/mL limits of detection, respectively, with nonvolatile reagents stored on-board and smartphone for detection. Reported LODs are lower than those concentrations used in the field. Additionally, the developed objective detection method addresses the testing of drugs with various common cutting agents, including those known to produce false negative and positive results. We demonstrate the effectiveness of the method by successfully identifying the composition of 30 unknown samples.

Rapid detection of Clostridium difficile via magnetic bead aggregation in cost-effective polyester microdevices with cell phone image analysis.

Pathogen detection has traditionally been accomplished by utilizing methods such as cell culture, immunoassays, and nucleic acid amplification tests; however, these methods are not easily implemented in resource-limited settings because special equipment for detection and thermal cycling is often required. In this study, we present a magnetic bead aggregation assay coupled to an inexpensive microfluidic fabrication technique that allows for cell phone detection and analysis of a notable pathogen in less than one hour. Detection is achieved through the use of a custom-built system that allows for fluid flow control via centrifugal force, as well as manipulation of magnetic beads with an adjustable rotating magnetic field. Cell phone image capture and analysis is housed in a 3D-printed case with LED backlighting and a lid-mounted Android phone. A custom-written application (app.) is employed to interrogate images for the extent of aggregation present following loop-mediated isothermal amplification (LAMP) coupled to product-inhibited bead aggregation (PiBA) for detection of target sequences. Clostridium difficile is a pathogen of increasing interest due to its causative role in intestinal infections following antibiotic treatment, and was therefore chosen as the pathogen of interest in the present study to demonstrate the rapid, cost-effective, and sequence-specific detection capabilities of the microfluidic platform described herein.

Long-Segment Intradural Extramedullary Teratoma of Dorsolumbar Spinal Cord in an Adolescent: A Rare Tumor with Review of Literature.

Spinal intradural extramedullary teratomas are rare tumors arising from more than one germ cell layers and are more common in children than in older age groups. Teratomas are more commonly seen in intracranial compartment and are extremely rare in the spine. They are difficult to diagnose pre-operatively and the definitive diagnosis is usually done by histopathologic evaluation. Intraspinal teratomas should be considered in the differential diagnosis of any intradural extramedullary tumor of the spine. We reviewed the literature and reported a rare case of intradural extramedullary teratoma in an adolescent located in dorsolumbar spine without any history of prior spinal procedure.

Hematocrit analysis through the use of an inexpensive centrifugal polyester-toner device with finger-to-chip blood loading capability.

Hematocrit (HCT) measurements are important clinical diagnostic variables that help physicians diagnose and treat various medical conditions, ailments, and diseases. In this work, we present the HCT Disc, a centrifugal microdevice fabricated by a Print, Cut and Laminate (PCL) method to generate a 12-sample HCT device from materials costing <0.5 USD (polyester and toner or PeT). Following introduction from a drop of blood (finger stick), whole blood metering and cell sedimentation are controlled by centrifugal force, only requiring a CD player motor as external hardware and, ultimately, a cell phone for detection. The sedimented volume from patient blood in the HCT Disc was analyzed using a conventional scanner/custom algorithm for analysis of the image to determine a hematocrit value, and these were compared to values generated in a clinical laboratory, which correlated well. To enhance portability and assure simplicity of the HCT measurement, values from image analysis by a cell phone using a custom application was compared to the scanner. Fifteen samples were analyzed with cell phone image analysis system and were found to be within 4% of the HCT values determined in the clinical lab. We demonstrate the feasibility of the PeT device for HCT measurement, and highlight its uniquely low cost (<0.5 USD), speed (sample-to-answer <8 min), multiplexability (12 samples), low volume whole blood requirement (<3 µL), rotation speeds (<4000 rpm) needed for effective measurement as well as the direct finger-to-chip sample loading capability.

Optical Imaging of Paramagnetic Bead-DNA Aggregation Inhibition Allows for Low Copy Number Detection of Infectious Pathogens.

DNA-paramagnetic silica bead aggregation in a rotating magnetic field facilitates the quantification of DNA with femtogram sensitivity, but yields no sequence-specific information. Here we provide an original description of aggregation inhibition for the detection of DNA and RNA in a sequence-specific manner following loop-mediated isothermal amplification (LAMP). The fragments generated via LAMP fail to induce chaotrope-mediated bead aggregation; however, due to their ability to passivate the bead surface, they effectively inhibit bead aggregation by longer 'trigger' DNA. We demonstrate the utility of aggregation inhibition as a method for the detection of bacterial and viral pathogens with sensitivity that approaches single copies of the target. We successfully use this methodology for the detection of notable food-borne pathogens Escherichia coli O157:H7 and Salmonella enterica, as well as Rift Valley fever virus, a weaponizable virus of national security concern. We also show the concentration dependence of aggregation inhibition, suggesting the potential for quantification of target nucleic acid in clinical and environmental samples. Lastly, we demonstrate the ability to rapidly detect infectious pathogens by utilizing a cell phone and custom-written application (App), making this novel detection modality fully portable for point-of-care use.