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Peptide nucleic acid (PNA) is an oligomer, in which the phosphate backbone has been replaced by a pseudopeptide backbone that is meant to mimic DNA. Peptide nucleic acids are of the utmost importance in the biomedical field because of their ability to hybridize with neutral nucleic acids and their special chemical and biological properties. In recent years, PNAs have emerged in nanobiotechnology for cancer diagnosis and therapy due to their high affinity and sequence selectivity toward corresponding DNA and RNA. In this review, we summarize the recent progresses that have been made in cancer detection and therapy with PNA biotechnology. In addition, we emphasize nanoparticle PNA-based strategies for the efficient delivery of drugs in anticancer therapies.

The high-density tungsten bronze Sr 2 NaNb 5 O 15 ceramics without abnormal grain growth were successfully synthesized by a two-step solid-state reaction method in this work. The phase evolution and reaction mechanism in SrNb 2 O 6 and NaNbO 3 solid solutions were analyzed by X-ray diffraction and differential scanning calorimetry. The results showed that the Sr 2 NaNb 5 O 15 phase could exist stably in the temperature range of 11001-13601C, and would be decomposed to SrNb 2 O 6 and NaNbO 3 phases at temperatures above 13601C. It was also found that the sintering temperature could significantly affect the density, microstructure, and electric properties of Sr 2 NaNb 5 O 15 ceramics. When the sintering temperature was 13401C, the ceramic with a near-theoretical density and a uniform and fine-grained microstructure was obtained, exhibiting outstanding electrical properties: e m 5 2210, tan d 5 0.023, T c 5 2801C, P r 5 11.71 lC/cm 2 , and E c 5 16.15 kV/cm. Further increasing the temperature to 13601C led to the existence of some molten areas and cracks on the surface of ceramics obtained, which could significantly deteriorate the electric properties. In addition, no abnormal large grains (450 lm) could be found in the system and the reason was also discussed in this paper.

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