A simple, disposable, and integrated electronic-tube cap (E-tube cap) for DNA detection at the point-of-care was designed, fabricated, and tested. The E-tube cap contains a 3D printed electrode substrate for DNA extraction and label-free pH sensing detection. One Flinders Technology Associates (Whatman FTA) membrane was incorporated into the 3D printed electrode substrate for the isolation, concentration, and purification of DNA.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2019
Physical forces have a profound effect on growth, morphology, locomotion, and survival of organisms. At the level of individual cells, the role of mechanical forces is well recognized in eukaryotic physiology, but much less is known about prokaryotic organisms. Recent findings suggest an effect of physical forces on bacterial shape, cell division, motility, virulence, and biofilm initiation, but it remains unclear how mechanical forces applied to a bacterium are translated at the molecular level.
View Article and Find Full Text PDFWe report the first characterization study of commercial prototype carbon nanotube (CNT) membranes consisting of sub-1.27-nm-diameter CNTs traversing a large-area nonporous polysulfone film. The membranes show rejection of NaCl and MgSO at higher ionic strengths than have previously been reported in CNT membranes, and specific size selectivity for analytes with diameters below 1.
View Article and Find Full Text PDFUnlabelled: Diffuse matrix damage in rat cortical bone has been observed to self-repair efficiently in 2 weeks without activating bone remodeling, and unlike the case with linear cracks, the local osteocytes at the sites of diffuse damage remain healthy. However, the reason(s) for such high efficiency of matrix repair remains unclear. We hypothesized that transport of minerals and other compounds essential for damage repair is enhanced at the damaged sites and further increased by the application of tensile loading.
View Article and Find Full Text PDFThe aim of this study was to understand the polymer degradation and drug release mechanism from PLGA microspheres embedded in a PVA hydrogel. Two types of microspheres were prepared with different molecular weight PLGA polymers (approximately 25 and 7 kDa) to achieve different drug release profiles, with a 9-day lag phase and without a lag phase, respectively. The kinetics of water uptake into the microspheres coincided with the drug release profiles for both formulations.
View Article and Find Full Text PDFThe ability to resist mechanical forces is necessary for the survival and division of bacteria and has traditionally been probed using specialized, low-throughput techniques such as atomic force microscopy and optical tweezers. Here we demonstrate a microfluidic technique to profile the stiffness of individual bacteria and populations of bacteria. The approach is similar to micropipette aspiration used to characterize the biomechanical performance of eukaryotic cells.
View Article and Find Full Text PDFThe mechanisms underlying the detection of critically loaded or micro-damaged regions of bone by bone cells are still a matter of debate. Our previous studies showed that calcium efflux originates from pre-failure regions of bone matrix and MC3T3-E1 osteoblasts respond to such efflux by an increase in the intracellular calcium concentration. The mechanisms by which the intracellular calcium concentration increases in response to an increase in the pericellular calcium concentration are unknown.
View Article and Find Full Text PDFThe two main types of mechanical stimuli used in cellular-level bone mechanotransduction studies are substrate strain and flow-induced shear stress. A subset of studies has investigated which of these stimuli induces the primary mechanotransduction effect on bone cells. The shortcomings of these experiments are twofold.
View Article and Find Full Text PDFThe mechanisms by which bone cells sense critically loaded regions of bone are still a matter of ongoing debate. Animal models to investigate response to microdamage involve post mortem immunohistological analysis and do not allow real-time monitoring of cellular response during the emergence of the damage in bone. Most in vitro mechanical stimulation studies are conducted on non-bone substrates, neglecting the damage-related alterations in the pericellular niche and their potential effects on bone cells.
View Article and Find Full Text PDFTopographical cues from the extracellular microenvironment can influence cellular activity including proliferation and differentiation. Information on the effects of material topography on tenogenic differentiation of human mesenchymal stem cells (human MSCs) is limited. A methodology using the principles of isoelectric focusing has previously been developed in our laboratory to synthesize electrochemically aligned collagen (ELAC) threads that mimics the packing density, alignment and strength of collagen dense connective tissues.
View Article and Find Full Text PDFBiomed Opt Express
November 2010
We demonstrate that the unique characteristics of random lasing in bone can be used to assess nanoscale structural alterations as a mechanical or structural biosensor, given that bone is a partially disordered biological nanostructure. In this proof-of-concept study, we conduct photoluminescence experiments on cortical bone specimens that are loaded in tension under mechanical testing. The ultra-high sensitivity, the large detection area, and the simple detection scheme of random lasers allow us to detect prefailure damage in bone at very small strains before any microscale damage occurs.
View Article and Find Full Text PDFGiven that bone is an intriguing nanostructured dielectric as a partially disordered complex structure, we apply an elastic light scattering-based approach to image prefailure deformation and damage of bovine cortical bone under mechanical testing. We demonstrate that our imaging method can capture nanoscale deformation in a relatively large area. The unique structure, the high anisotropic property of bone, and the system configuration further allow us to use the transfer matrix method to study possible spectroscopic manifestations of prefailure deformation.
View Article and Find Full Text PDFOwing to the low-loss and high refractive index variations derived from the basic building block of bone structure, we, for the first time to our knowledge, demonstrate coherent random lasing action originated from the bone structure infiltrated with laser dye, revealing that bone tissue is an ideal biological material for random lasing. Our numerical simulation shows that random lasers are extremely sensitive to subtle structural changes even at nanoscales and can potentially be an excellent tool for probing nanoscale structural alterations in real time as a novel spectroscopic modality.
View Article and Find Full Text PDFA prominent opacity is evident in the process zone of notched thin wafers of bone loaded in tension. Being recoverable upon unloading, this opaque zone can be stained only when the sample is under load, unlike the classically reported forms of damage which take up the stain in the unloaded state. Furthermore, despite the stain uptake, microcracks are absent in the stained area examined by high magnification optical microscopy and atomic force microscopy (AFM).
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