ABSTRACT
@#Small interfering RNA-based RNA interference(RNAi)is an emerging treatment which has attracted more and more attention from both academia and industry. Studies on clinical translation of siRNA are popular in biomedical field, where safe and efficient carriers are necessary. As novel drug/gene vectors, dendrimers are widely used in siRNA delivery due to their unique and precise structure, multiple terminal groups and nano-sized chemophysical properties. Here, we present an overall view of current studies on dendrimer-based siRNA delivery systems, with the aim to provide an understanding of future siRNA therapeutics which could be used in clinic.
ABSTRACT
@#In comparison with the traditional two-dimensional tumor cell culture, the three-dimensional tumor spheroid culture can not only provide with an in vivo-like growth environment for tumor cells, but also maintain maximum cell activities. Therefore, the three-dimensional tumor spheroid culture is widely used in oncology research. In particular, the three-dimensional tumor cells retain the material and structural basis of the microenvironment of tumor in vivo, which is closer to the actual physiological environment, allowing it to be an ideal in vitro model for evaluating the tumor treatment response and drug resistance in tumors. This review summarizes the mechanisms of drug resistance in three-dimensional tumor cells, especially those induced by the morphology and microenvironment of three-dimensional tumor spheres, and puts forward the problems existing in the current three-dimensional tumor cells model, as well as the future development direction.
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BACKGROUND:Hydroxyapatite-coated titanium substrates improve the biocompatibility and have the property of intimating ossteointegration with host bonebed. However, hydroxyapatite lacks the necessary mechanical strength and degrades easily in the extracelular fluids, which may affect the stability of the titanium implant. OBJECTIVE:To study the synthesis and characterization of lanthanum-incorporated hydroxyapatite coatings. METHODS: Lanthanum-incorporated hydroxyapatite coatings were prepared by hydroxyapatite and 10%, 20% and 30% lanthanum, respectively, by means of sol-gel, which were then deposited on titanium substrates with dip-withdrawal technique. Surface morphology and crystaline microstructure of the coatings were observed by scanning electron microscope. The presence of functional groups for the obtained samples was performed by Fourier transform infrared absorption spectroscopy and X-ray diffraction. The Ca2+ concentration released from the coatings was measured by atomic absorption spectrometry for analysis of degradation property. RESULTS AND CONCLUSION: With the increase of lanthanum content, the diffraction peak and crystalinity of lanthanum-incorporated hydroxyapatite coatings were increased, but the whole structure of lanthanum-incorporated hydroxyapatites had little changes. The crystal structure maintained stable with charge balance. The lanthanum-incorporated hydroxyapatite coatings showed uniform and high-dense structure and were free of cracks, indicating the coatings had good bonding strength. Under the simulated biological environment, based on the determination of Ca2+ release from the coatings, we can conclude the lanthanum-incorporated hydroxyapatite coatings have a stronger acidoresistance.