Uniform silver-containing metal nanostructures with well-defined nanogaps hold great promise for ultrasensitive surface-enhanced Raman scattering （SERS） analyses. Nevertheless, the direct synthesis of such nanostruc...Uniform silver-containing metal nanostructures with well-defined nanogaps hold great promise for ultrasensitive surface-enhanced Raman scattering （SERS） analyses. Nevertheless, the direct synthesis of such nanostructures with strong and stable SERS signals remains extremely challenging. Here, we report a DNA-mediated approach for the direct synthesis of gold-silver nano-mushrooms with interior nanogaps. The SERS intensities of these nano-mushrooms were critically dependent on the area of the nanogap between the gold head and the silver cap. We found that the formation of nanogaps was finely tunable by controlling the surface density of 6-carboxy-X-rhodamine （ROX） labeled single-stranded DNA （ssDNA） on the gold nanoparticles. We obtained nano-mushrooms in high yield with a high SERS signal enhancement factor of -1.0×109, much higher than that for Au-Ag nanostructures without nanogaps. Measurements for single nano- mushrooms show that these structures have both sensitive and reproducible SERS signals.展开更多
Monitoring telomerase activity with high sensitive and reliable is of great importance to cancer analysis. In this paper, we report a sensitive and facile method to detect telomerase activity using AIEgens mod- ified ...Monitoring telomerase activity with high sensitive and reliable is of great importance to cancer analysis. In this paper, we report a sensitive and facile method to detect telomerase activity using AIEgens mod- ified probe （TPE-Py-DNA） as a fluorescence reporter and exonuclease llI （Exo lIl） as a signal amplifier. With the aid of telomerase, repeat units （TrAGGG）n are extended from the end of template substrate oligonucleotides （TS primer） that form duplex DNAs with TPE-Py-DNA. Then, Exo llI catalyzes the diges- tion of duplex DNAs, liberating elongation product and releasing hydrophobic TPE-Py. The released hydrophobic TPE-Py aggregate together and produce a telomerase-activity-related fluorescence signal. The liberated product hybridizes with another TPE-Py-DNA probe, starting the second cycle. Finally, we obtain the target-to-signal amplification ratio of 1 ：N2. This strategy exhibits good performance for detecting clinical urine samples （distinguishing 15 cancer patients＇ samples from 8 healthy ones） and checking intracellular telomerase activity （differentiating cell lines including HeLa, MDA-MB-231, MCF-7, A375, HLF and MRC-5 from the cells pretreated with telomerase-related drug）, which shows its potential in clinical diagnosis as well as therapeutic monitoring of cancer.展开更多
It has been found that a triple-node feed-forward motif has a function of signal amplification, where two input nodes receive the external weak signal and jointly modulate the response of the third output node [Liang ...It has been found that a triple-node feed-forward motif has a function of signal amplification, where two input nodes receive the external weak signal and jointly modulate the response of the third output node [Liang et al.,Phys. Rev. E 88（2013） 012910]. We here show that the signal amplification can be further enhanced by adding a link between the two input nodes in the feed-forward motif. We further reveal that the coupling strength of the link regulates the enhancement of signal amplification in the modified feed-forward motif. We finally analyze the mechanism of signal amplification of such simple structure.展开更多
Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled ...Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are fh-stly built, then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure （NF）.展开更多
基金We thank the National Basic Research Program of China （973 program） （Nos. 2013CB932802 and 2012CB932600）,Alexander von Humboldt Foundation, and the National Natural Science Foundation of China （Nos. 91127037 and 91123037） for financial support.
文摘Uniform silver-containing metal nanostructures with well-defined nanogaps hold great promise for ultrasensitive surface-enhanced Raman scattering （SERS） analyses. Nevertheless, the direct synthesis of such nanostructures with strong and stable SERS signals remains extremely challenging. Here, we report a DNA-mediated approach for the direct synthesis of gold-silver nano-mushrooms with interior nanogaps. The SERS intensities of these nano-mushrooms were critically dependent on the area of the nanogap between the gold head and the silver cap. We found that the formation of nanogaps was finely tunable by controlling the surface density of 6-carboxy-X-rhodamine （ROX） labeled single-stranded DNA （ssDNA） on the gold nanoparticles. We obtained nano-mushrooms in high yield with a high SERS signal enhancement factor of -1.0×109, much higher than that for Au-Ag nanostructures without nanogaps. Measurements for single nano- mushrooms show that these structures have both sensitive and reproducible SERS signals.
基金supported by the National Natural Science Foundation of China(21375042,21405054,21525523,21574048,and21404028)the National Basic Research Program of China(2015CB932600,2013CB933000,and 2016YFF0100800)+1 种基金the Special Fund for Strategic New Industry Development of Shenzhen,China(JCYJ20150616144425376)1000 Young Talent Program(to F.Xia)
文摘Monitoring telomerase activity with high sensitive and reliable is of great importance to cancer analysis. In this paper, we report a sensitive and facile method to detect telomerase activity using AIEgens mod- ified probe （TPE-Py-DNA） as a fluorescence reporter and exonuclease llI （Exo lIl） as a signal amplifier. With the aid of telomerase, repeat units （TrAGGG）n are extended from the end of template substrate oligonucleotides （TS primer） that form duplex DNAs with TPE-Py-DNA. Then, Exo llI catalyzes the diges- tion of duplex DNAs, liberating elongation product and releasing hydrophobic TPE-Py. The released hydrophobic TPE-Py aggregate together and produce a telomerase-activity-related fluorescence signal. The liberated product hybridizes with another TPE-Py-DNA probe, starting the second cycle. Finally, we obtain the target-to-signal amplification ratio of 1 ：N2. This strategy exhibits good performance for detecting clinical urine samples （distinguishing 15 cancer patients＇ samples from 8 healthy ones） and checking intracellular telomerase activity （differentiating cell lines including HeLa, MDA-MB-231, MCF-7, A375, HLF and MRC-5 from the cells pretreated with telomerase-related drug）, which shows its potential in clinical diagnosis as well as therapeutic monitoring of cancer.
基金Supported by the Program for Professor of Special Appointment（Eastern Scholar） at Shanghai Institutions of Higher Learning under Grant No.QD2015016 the National Natural Science Foundation of China under Grant Nos.11505114 and 11305078
文摘It has been found that a triple-node feed-forward motif has a function of signal amplification, where two input nodes receive the external weak signal and jointly modulate the response of the third output node [Liang et al.,Phys. Rev. E 88（2013） 012910]. We here show that the signal amplification can be further enhanced by adding a link between the two input nodes in the feed-forward motif. We further reveal that the coupling strength of the link regulates the enhancement of signal amplification in the modified feed-forward motif. We finally analyze the mechanism of signal amplification of such simple structure.
基金supported by the National Basic Research Program of China (973 Program) (No.2010CB328304)
文摘Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are fh-stly built, then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure （NF）.
