Exosomes are secreted by most cell types and circulate in body fluids. Recent studies have revealed that exosomes play a significant role in intercellular communication and are closely associated with the pathogenesis of disease. Therefore, exosomes are considered promising biomarkers for disease diagnosis. However, exosomes are always mixed with other components of body fluids. Consequently, separation methods for exosomes that allow high‐purity and high‐throughput separation with a high recovery rate and detection techniques for exosomes that are rapid, highly sensitive, highly specific, and have a low detection limit are indispensable for diagnostic applications. For decades, many exosome separation and detection techniques have been developed to achieve the aforementioned goals. However, in most cases, these two techniques are performed separately, which increases operation complexity, time consumption, and cost. The emergence of microfluidics offers a promising way to integrate exosome separation and detection functions into a single chip. Herein, an overview of conventional and microfluidics‐based techniques for exosome separation and detection is presented. Moreover, the advantages and drawbacks of these techniques are compared.
A chemiresistive
gas sensor based on a three-dimensional Ag-modified
reduced graphene oxide (3D Ag-rGO) aerogel is reported. We improve
the graphene-based sensor performance by optimization of operating
temperature, chemical modification, and new design of the material
geometrical structure. The self-assembly and Ag nanoparticle (NP)
decoration of the Ag-rGO aerogel are realized by a facile, one-step
hydrothermal method. An integrated low-power microheater fabricated
on a micromachined SiO2 membrane is employed to enhance
the performance of the sensor with a fast response to NO2 and a shortened recovery time. The 3D Ag-rGO-based sensor at a temperature
of 133 °C exhibits the highest response. At the same time, the
response to other gases is suppressed while the response of the Ag-rGO
sensor toward ammonia at 133 °C is reduced to half of the value
at room temperature, demonstrating a greatly improved selectivity
toward NO2. Additionally, the sensor exhibits a remarkably
fast response to 50 ppb NO2 and a low limit of detection
of 6.9 ppb.
Malignant glioma is a highly aggressive brain tumor with a poor prognosis. Chemotherapy has been observed to prolong overall survival rate and temozolomide (TMZ), a promising chemotherapeutic agent for treating glioblastoma (GBM), possesses the most effective clinical activity at present, although drug resistance limits its clinical outcome. Growing evidence supports the concept that initial and recurrent GBM may derive from glioblastoma stem cells, which may be responsible for drug resistance. However, the molecular mechanisms underlying this resistance remain to be elucidated. In the present study, a TMZ-resistant GBM cell line, U251R, was developed and subsequently divided into two subpopulations according to the CD133 immunophenotype. No significant difference was identified in the expression of O6-methylguanine-DNA-methyltransferase (MGMT) between CD133+ U251R cells and CD133− U251R cells, whereas the CD133+ cell population was more resistant to TMZ-induced growth inhibition and cell death. TMZ achieves its cytotoxic effect by inducing DNA lesions and p53 upregulated modulator of apoptosis (PUMA) is an essential mediator of DNA damage-induced apoptosis independently of p53 status. Therefore, whether PUMA effectively enhances growth suppression and induces apoptosis when combined with TMZ was investigated. Consequently, it was found that adenoviruses expressing wild-type-PUMA not only lead to the apoptosis of CD133+ U251R cells alone, but also significantly increase their sensitivity toward TMZ by elevating the Bcl-2-associated X protein/B-cell lymphoma-2 ratio without alterations in MGMT expression. Therefore, PUMA may be a suitable target for intervention to improve the therapeutic efficacy of TMZ.
Recovery
of vanadium from various sources is important to the environment
and industry. This work investigates vanadium leaching from a spent
selective catalytic reduction catalyst by sulfuric acid at atmospheric
pressure. It includes the effects of stirring speed, solid to liquid
ratio, temperature, and sulfuric acid concentration on the vanadium
recovery yield. The results show that the vanadium recovery yield
increases with increases in temperature, sulfuric acid concentration,
and leaching time and decreases with an increase in solid to liquid
ratio. The leaching data can not be described well by kinetic models
commonly adopted for similar processes in the literature. The Avrami
equation, originally developed for crystallization, is found to be
most suitable. The leaching is controlled by diffusion in the solid
with an activation energy of 5.90 kJ/mol.
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