A guanidinium-rich polymer as a new universal bioreceptor for multiplex detection of bacteria from environmental samples.

Protamine, a guanidinium rich polymer, is proposed as a universal bioreceptor for bacteria, towards rapid and handheld bacteria detection from complex environmental water samples without the need for specific antibodies or primers. Escherichia coli K12, Salmonella Typhimurium, and Staphylococcus aureus (MSSA) were assayed, representing gram-negative, gram-positive, rod- and round-shaped bacteria. Samples and the protamine conjugated fluorescent particles were sequentially loaded to the paper microfluidic chips and flowed through the channels spontaneously via capillary action. The particles were aggregated via protamine-bacteria membrane interactions and unbound particles were rinsed via capillary action. A low-cost smartphone fluorescence microscope was designed, fabricated, and imaged the paper channels. A unique image processing algorithm isolated only the aggregated particles to detect all three bacteria (p < 0.05) with a detection limit of 101-102 CFU/mL. Protamine did not induce any particle aggregation with a model protein, algae, and virus. Successful bacteria detection was also demonstrated with environmental field water samples. Total assay time was < 10 min with neither extraction nor enrichment steps. In summary, a guanidinium-rich polymer showed a promise as a universal bioreceptor for bacteria and can be used on a paper microfluidic chip and smartphone quantification towards rapid and handheld detection.

Translationally Relevant Magnetic Resonance Imaging Markers in a Ferret Model of Closed Head Injury.

Pre-clinical models of traumatic brain injury (TBI) have been the primary experimental tool for understanding the potential mechanisms and cellular alterations that follow brain injury, but the human relevance and translational value of these models are often called into question. Efforts to better recapitulate injury biomechanics and the use of non-rodent species with neuroanatomical similarities to humans may address these concerns and promise to advance experimental studies toward clinical impact. In addition to improving translational aspects of animal models, it is also advantageous to establish pre-clinical outcomes that can be directly compared with the same outcomes in humans. Non-invasive imaging and particularly MRI is promising for this purpose given that MRI is a primary tool for clinical diagnosis and at the same time increasingly available at the pre-clinical level. The objective of this study was to identify which commonly used radiologic markers of TBI outcomes can be found also in a translationally relevant pre-clinical model of TBI. The ferret was selected as a human relevant species for this study with folded cortical geometry and relatively high white matter content and the closed head injury model of engineered rotation and acceleration (CHIMERA) TBI model was selected for biomechanical similarities to human injury. A comprehensive battery of MRI protocols based on common data elements (CDEs) for human TBI was collected longitudinally for the identification of MRI markers and voxelwise analysis of T2, contrast enhancement and diffusion tensor MRI values. The most prominent MRI findings were consistent with focal hemorrhage and edema in the brain stem region following high severity injury as well as vascular and meningeal injury evident by contrast enhancement. While conventional MRI outcomes were not highly conspicuous in less severe cases, quantitative voxelwise analysis indicated diffusivity and anisotropy alterations in the acute and chronic periods after TBI. The main conclusions of this study support the translational relevance of closed head TBI models in intermediate species and identify brain stem and meningeal vulnerability. Additionally, the MRI findings highlight a subset of CDEs with promise to bridge pre-clinical studies with human TBI outcomes.