Background
MicroRNAs have short sequences of 20 ~ 25-nucleotides which are similar among family members and play crucial regulatory roles in numerous biological processes, such as in cell development, metabolism, proliferation, differentiation, and apoptosis.
Results
We reported a strategy for the construction of a dual-emission fluorescent sensor using carbon dots (CDs) and confirmed their applications for ratiometric microRNA-21 sensing and bioimaging of cancer cells in a microfluidic device. The composition of blue CDs (B-CDs) and yellow CDs (Y-CDs) depicts dual-emission behavior which is centered at 409 and 543 nm under an excitation wavelength of 360 nm. With increasing microRNA-21 concentration, the robust and specific binding of DNA probe functionalized B-CDs to complementary microRNA-21 target induced perturbations of probe structure and led to changing fluorescence intensity in both wavelengths. Consequently, the ratio of turn-on signal to turn-off signal is greatly altered. With monitoring of the inherent ratiometric fluorescence variation (ΔF540nm/ΔF410nm), as-prepared BY-CDs were established as an efficient platform for ratiometric fluorescent microRNA-21 sensing, with a wide linear range of 0.15 fM to 2.46 pM and a detection limit of 50 aM.
Conclusions
Furthermore, the proposed assay was applied for detecting microRNA-21 in dilute human serum samples with satisfactory recovery and also in MCF-7 cell lines in the range 3000 to 45,000 (cell mL−1) with a detection limit (3 cells in 10 μL), demonstrating the potential of the assay for clinic diagnosis of microRNA-associated disease. More importantly, the images revealed that MCF-7 cells well labeled with BY-CDs could exhibit the applicability of the proposed microfluidic system as an effective cell trapping device in bioimaging.
Graphical Abstract
Angiogenesis is a strictly controlled process defined as the formation of new blood vessels essential for certain physiologic and pathologic conditions where the latter includes tumor growth, development, and metastasis. Thus, inhibiting angiogenesis along with other anticancer strategies such as chemotherapy seems to be invaluable for reaching an optimal outcome in cancer patients. It has been shown that some natural plant-derived compounds are capable of preventing the formation of these new blood vessels in the tumor and also inhibit the proliferation and growth of the cancer cells. In this review, we intend to introduce plants with anti-angiogenic properties and discuss their related features.
Nowadays, nanofibers have various applications in the field of medical biology including drug delivery systems (DDSs) and tissue engineering. Many methods have been developed to produce drug release polymers; the most important and applicable of which is known as electrospinning. In this method, the nanoscale and microscale fibers are used as the functional polymers in the DDSs. A variety of electrospinning methods can be used for delivery systems and tissue engineering. The nanofibers loaded with anticancer drugs have attracted a lot of attention in the last decade. Electrospun parameters include voltage, feed rate, rotary collector, pipette or needle hole diameter, the distance between nozzle tip to collector plate, viscosity and molecular weight of the polymer, surface tension, solubility of polymer, soluble electrical conductivity, dielectric constant, and evaporability of the solution; all could be manipulated to regulate the drug release rate in order via changing the diameter of the nanofibers. In addition to directly loading the drug on nanofibers, the nanoparticles are also used to improve the drug efficacy and reduce the required dose, especially in the case of harmful drugs. Depending on the need, various nanoparticles and nanocarriers are being applied along with the drug. Nanocarriers such as viruses, micelles, and liposomes function highly specific since they carry specific ligands on their surface. Magnetic nanoparticles also have a great therapeutic effect on cancer cells when exposed to heat and magnetic fields. Carbon nanoparticles, such as graphene and graphene oxide, due to their layering, can pass through the cell membrane and deliver the drug to the intracellular space.
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