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Obesity is a complex metabolic disease that is a serious detriment to both children and adult health, which induces a variety of diseases, such as cardiovascular disease, type II diabetes, hypertension and cancer. Although adverse effects of obesity on female reproduction or oocyte development have been well recognized, its harmfulness to male fertility is still unclear because of reported conflicting results. The aim of this study was to determine whether diet-induced obesity impairs male fertility and furthermore to uncover its underlying mechanisms. Thus, male C57BL/6 mice fed a high-fat diet (HFD) for 10 weeks served as a model of diet-induced obesity. The results clearly show that the percentage of sperm motility and progressive motility significantly decreased, whereas the proportion of teratozoospermia dramatically increased in HFD mice compared to those in normal diet fed controls. Besides, the sperm acrosome reaction fell accompanied by a decline in testosterone level and an increase in estradiol level in the HFD group. This alteration of sperm function parameters strongly indicated that the fertility of HFD mice was indeed impaired, which was also validated by a low pregnancy rate in their mated normal female. Moreover, testicular morphological analyses revealed that seminiferous epithelia were severely atrophic, and cell adhesions between spermatogenic cells and Sertoli cells were loosely arranged in HFD mice. Meanwhile, the integrity of the blood-testis barrier was severely interrupted consistent with declines in the tight junction related proteins, occludin, ZO-1 and androgen receptor, but instead endocytic vesicle-associated protein, clathrin rose. Taken together, obesity can impair male fertility through declines in the sperm function parameters, sex hormone level, whereas during spermatogenesis damage to the blood-testis barrier (BTB) integrity may be one of the crucial underlying factors accounting for this change.

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The two-dimensional arrays of various metal nanowires with diameters ranging from 15 to 70 nm have been fabricated by electrodepositing metals of Cu, Ag, Au, Ni, and Co into the nanoholes of the anodic aluminum oxide (AAO) films, followed by partial removal of the film. The strong surface-enhanced Raman scattering (SERS) effects were observed from the metal nanowire arrays including Ni, Co metals that were normally considered to be non-SERS active substrates. It has been shown that metal nanowire arrays can serve as very good SERS active substrates, especially for transition metals. The SERS intensity of the probe molecule adsorbed at the nanowires depends critically on the length of the nanowires explored at the surface. And the band frequency is very sensitive to the diameter, which reflects the change in the electronic property of metal nanowires. Applying this probe molecule strategy, SERS could develop into a diagnostic tool of metal nanowires (nanorods).

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