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1.
Biosens Bioelectron ; 156: 112128, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32174556

RESUMO

Field effect transistor (FET) biosensors based on low-dimensional materials have the advantages of small in size, simple structure, fast response and high sensitivity. In this work, a field-effect transistor biosensor based on molybdenum disulfide/graphene (MoS2/graphene) hybrid nanostructure was proposed and fabricated for DNA hybridization detection. The biosensor achieved an effective response to DNA concentrations in a broad range from 10 aM to 100 pM and a limit of detection (LOD) of 10 aM was obtained, which was one or more orders of magnitude lower than the reported result. The sensing mechanisms (donor and gating effects) of the FET sensor were discussed. A larger voltage shift of the charge neutral point was obtained due to a strengthened donor effect and a weakened gating effect caused by the introduction of MoS2 layers. Such FET sensor shows high specificity for different matching degrees of complementary DNA, indicating the potential use of such a sensor in disease diagnosis.

2.
Opt Express ; 27(18): 25091-25106, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31510388

RESUMO

We report a structure to form a hybrid system in which a mesh is sandwiched between Au nanoparticles (AuNPs) and Ag nanoparticles (AgNPs). This self-assembly method uses smaller and denser AgNPs "hot spots" that are spin-coated on a AuNPs@GO mesh nanostructure formed by the reaction of GO@MoS2 and HAuCl4 to form AuNPs@GO mesh@AgNPs SERS substrates. Sub-40-nm mesh and 10-nm gaps ensure the landing sites and spacing of the AgNPs. Consequently, the design integrates the strong plasmonic effects of AgNPs and AuNPs with the biological compatibility of the GO mesh. Crystal violet (CV) as low as 10-15 M can be detected, which confirms the ultrahigh sensitivity of AuNPs@GO mesh@AgNPs. Furthermore, the reproducibility, stability, and finite-difference time-domain (FDTD) simulations confirm the value of this SERS substrate. This material can be used for label-free DNA detection, and the AuNPs@GO mesh@AgNPs substrate facilitated single-molecule DNA detection limits.

3.
Nanomaterials (Basel) ; 9(9)2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31466375

RESUMO

In this study, a double-end pumped high-power passively mode-locked erbium-doped fiber laser (EDFL) was realized by employing a few-layered In2Se3 flakes as a saturable absorber (SA). Herein, the uniform large-scale In2Se3 flakes were synthesized by the physical vapor deposition (PVD) method. The PVD-In2Se3 SA exhibited a remarkable damage threshold of higher than 24 mJ/cm2. Meanwhile, the PVD-In2Se3 SA had a modulation depth and saturable intensity of 18.75% and 6.8 MW/cm2, respectively. Based on the In2Se3 SA, the stable bright pulses emitting at 1559.4 nm with an average output power/pulse energy/pulse duration of 122.4 mW/5.8 nJ/14.4 ns were obtained successfully. To our knowledge, 122.4 mW was the new major breakthrough of mode-locked Er-doped fiber lasers. In addition, this is the first demonstration of the dark-bright pulse pair generation based on In2Se3 SA. The maximum average output power of the dark-bright pulse reached 121.2 mW, which also showed significant enhancement in comparison with previous works. Our excellent experiment results fully prove the superiority of our experimental design scheme and indicate that the PVD-In2Se3 could operate as a promising highly-nonlinear photonic material for a high-power fiber laser.

4.
J Phys Chem Lett ; 10(13): 3676-3680, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31204810

RESUMO

The vertically interlaced hierarchical structure (HS) of ZnO nanosheets (NSs)@Ag nanoravines (NRs) as a quasi optical cavity (QOC) for Raman enhancement has been studied experimentally and theoretically in this work. A novel synergism of near- and far-field effects of Ag NRs is facilitated by the multiple oscillation of light inside the ZnO QOC, providing wide distributions of "hot spots" in a large space. The "spatial hot spots" in the HS bring reliable signal collection in in situ Raman detection. Without any specific materials and methods adopted, this HS provides researchers a new way to adjust the light in the fields of Raman enhancement.

5.
Biosens Bioelectron ; 137: 255-262, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31121462

RESUMO

A suspended carbon nanotube (SCNT)-based field effective transistor (SCNT-FET), which was fabricated by utilizing the surface tension of liquid silver to suspend a CNT between two Pd electrodes, was proposed for the detection of DNA hybridization. Benefits from the separation between the CNT and the substrates could be observed; namely, the conductivity of a SCNT-FET was much higher (two orders of magnitude) than that of a FET based on an unsuspended CNT and about 50% sensing surface of CNT was freed from substrate. The Slater-Koster tight-binding method was adopted for geometry optimization and transport property calculation of the SCNT bound with DNA. The result showed that the conductance (G = 1/R) of the SCNT decreased in order with the binding of single-stranded DNA (SSDNA, probe DNA) and double-stranded DNA (DSDNA) and that the ability of DSDNA to weaken the conductivity of the SCNT was several times higher than that of SSDNA. SEM and Raman spectroscopy were used to demonstrate that DNA could be bound successfully onto the SCNT using a 1-pyrenebutanoic acid succinimidyl ester (PBASE) as a linkage. Ultra-high sensitivity detection of DNA [with a limit of detection (LOD) as low as 10 aM] was obtained using such an SCNT-FET, which showed a lower value than that of a previously reported FET DNA biosensor whose sensing materials were in direct contact with the substrate.


Assuntos
Técnicas Biossensoriais , DNA/isolamento & purificação , Hibridização de Ácido Nucleico , DNA/química , Sondas de DNA/química , DNA de Cadeia Simples/química , Condutividade Elétrica , Limite de Detecção , Nanotubos de Carbono/química , Análise Espectral Raman , Transistores Eletrônicos
6.
Appl Opt ; 58(10): 2695-2701, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31045075

RESUMO

We reported on the generation of pulse bunch and large-energy dark pulses in a mode-locked ytterbium-doped linear-cavity fiber laser based on Bi2Se3 as a saturable absorber (SA). Bi2Se3 nanosheets were successfully synthesized by the chemical vapor deposition (CVD) method and transferred to the end facet of a fiber connector for the proposed SA. Its saturation intensity and modulation depth were measured to be 52 MW/cm2 and 14.5%, respectively. By inserting the Bi2Se3-based SA into the Yb-doped all-fiber linear cavity, stable pulse bunches were observed. In addition, dark soliton operation with a maximum average output power of 32.6 mW and a pulse energy of 61.8 nJ were also achieved. To the best of our knowledge, this is the first demonstration of a dark soliton within a linear cavity with much larger pulse energy than previous works. Our study fully indicated that CVD-Bi2Se3 could be an excellent SA for achieving large-energy pulse operations.

7.
Opt Express ; 27(7): 9879-9894, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31045136

RESUMO

To realize fast detection of trace hazardous chemicals, a SERS substrate with the structure of a blackberry-like silver/graphene oxide nanoparticle cluster (Ag/GO NPC) has been designed and prepared through a quick capillarity-assistant self-assembly technology in this paper. Benefitting from the abundant "hot spots" and active oxygen sites brought by this Ag/GO NPC, the substrate shows good Raman performance for malachite green (MG), a common abusive germicide in aquaculture, with lowest limit of detection below 0.1 µg/L (3.48 × 10-10 mol/L). Detailed analyses are taken on both the formation process and enhancement mechanism of this SERS substrate, and the finite-difference time-domain simulations are utilized as well to prove our hypotheses. Further constructing this structure on polyethylene terephthalate (PET) film, a translucent flexible SERS substrate can be obtained, realizing a fast in situ detection of trace MG in the fishpond subsequently. In consideration of the facile preparation process, good SERS enhancement and affordable materials (PET, Cu, Ag and GO, etc.), this substrate presents high cost performance and a promising application prospect.

8.
Nanomaterials (Basel) ; 9(5)2019 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-31060316

RESUMO

We demonstrate the generation of versatile mode-locked operations in an Er-doped fiber laser with an indium tin oxide (ITO) saturable absorber (SA). As an epsilon-near-zero material, ITO has been only used to fashion a mode-locked fiber laser as an ITO nanoparticle-polyvinyl alcohol SA. However, this type of SA cannot work at high power or ensure that the SA materials can be transmitted by the light. Thus, we covered the end face of a fiber with a uniform ITO film using the radio frequency magnetron sputtering technology to fabricate a novel ITO SA. Using this new type of SA, single-wavelength pulses, dual-wavelength pulses, and triple-wavelength multi-pulses were achieved easily. The pulse durations of these mode-locked operations were 1.67, 6.91, and 1 ns, respectively. At the dual-wavelength mode-locked state, the fiber laser could achieve an output power of 2.91 mW and a pulse energy of 1.48 nJ. This study reveals that such a proposed film-type ITO SA has excellent nonlinear absorption properties, which can promote the application of ITO film for ultrafast photonics.

9.
Lasers Med Sci ; 34(9): 1849-1855, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30989458

RESUMO

Despite the rapid development of medical science, the diagnosis of lung cancer is still quite challenging. Due to the ultrahigh detection sensitivity of surface-enhanced Raman spectroscopy (SERS), SERS has a broad application prospect in biomedicine, especially in the field of tumor blood detection. Although Raman spectroscopy can diagnose lung cancer through tissue slices, its weak cross sections are problematic. In this study, silver nanoparticles (AgNPs) were added to the surface of lung tissue slices to enhance the Raman scattering signals of biomolecules. The electromagnetic field distribution of AgNPs prepared was simulated using the COMSOL software. SERS obtained from the slices reflected the difference in biochemical molecules between normal (n = 23) and cancerous (n = 23) lung tissues. Principal component-linear discriminate analysis (PCA-LDA) was utilized to classify lung cancer and healthy lung tissues. The receiver operating characteristic curve gave the sensitivity (95.7%) and specificity (95.7%) of the PCA-LDA method. This study sheds new light on the general applicability of SERS analysis of tissue slices in clinical trials.


Assuntos
Neoplasias Pulmonares/diagnóstico , Análise Espectral Raman/métodos , Estatística como Assunto , Adulto , Idoso , Feminino , Humanos , Masculino , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Pessoa de Meia-Idade , Análise Multivariada , Análise de Componente Principal , Prata/química , Coloração e Rotulagem
10.
Opt Express ; 27(3): 3000-3013, 2019 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-30732328

RESUMO

In recent years, biomaterials have increasingly attracted attention on surface-enhanced Raman spectroscopy (SERS) due to their well Raman performance while metal particles are combined with biological substrates. Therefore, we propose an environmentally friendly substrate based on silver-plated cicada wings with seamless graphene layer (Gr-AgNPs-C.w.), which can be prepared with a simple and inexpensive method. Compared with AgNPs-C.w., Gr-AgNPs-C.w. hybrids show better SERS performance with high sensitivity, good uniformity and good stability with R6G detection. The minimum detected concentration can reach 10-15 M, and the value of R2 can reach 0.996, respectively. Theoretical simulation demonstrates the situation of electromagnetic field through COMSOL software. In addition, due to the affinity of graphene for biomolecules, we can successfully detect the DNA biomolecules through a simple process. Therefore, this cheap and efficient natural SERS substrate has great potential for a considerable number of biochemical SERS applications and can broaden the way in which multiple SERS platforms derived from other natural materials are prepared.


Assuntos
DNA/análise , Grafite/química , Hemípteros/química , Nanopartículas Metálicas/química , Prata/química , Análise Espectral Raman/métodos , Animais
11.
Opt Express ; 27(3): 3483-3495, 2019 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-30732368

RESUMO

A D-shape plastic optical fiber (D-POF) surface plasmon resonance (SPR) biosensor based on the graphene/Au film (G/Au) was proposed and experimentally demonstrated for detection of DNA hybridization process. To improve the detection performance of SPR sensors, the Physical Vapor Deposition (PVD) method was used to evaporate the Au film directly onto the graphene grown on copper foil, and the Au film acted as a role of traditional Polymethyl Methacrylate (PMMA). The process made graphene and Au film form seamless contact. Next, the G/Au was transferred onto the D-shape fiber together. We explored the G/Au SPR sensor by using the finite element method (FEM) and obtained the optimum materials thickness to form configuration. Compared to other plastic optical fiber experiments, the proposed sensor's sensitivity was improved effectively and calculated as 1227 nm/RIU in a range of glucose solution. Meanwhile, our proposed sensor successfully distinguishes hybridization and single nucleotide polymorphisms (SNP) by observing the resonance wavelength change. It also exhibits a satisfactory linear response (R2 = 0.996) to the target DNA liquids with respective concentrations of 0.1nM to1µM, which shows this method's wide potential in medical diagnostics.

12.
Appl Opt ; 57(30): 8811-8818, 2018 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-30461861

RESUMO

Different large-energy mode-locked operations were successfully obtained within a Bi2Se3-based Er-doped fiber laser. First, mode-locked operation with maximum pulse energy of 17.2 nJ and pulse width of 187 ns under a pulse repetition rate of 537.6 kHz was obtained under the pump power of 680 mW. In addition, the characteristics of dark solitons and soliton rains, which also exhibit large pulse energies, have been investigated experimentally. Our results fully proved that Bi2Se3 was an excellent candidate for investigating various mode-locked operations with large pulse energy due to its high nonlinear effect and high damage threshold.

13.
Opt Express ; 26(18): 23831-23843, 2018 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-30184879

RESUMO

The heterogeneous metal nanostructures have attracted great interest in various applications due to the synergistic effects between two noble metals, especially in surface enhanced Raman scattering (SERS) region. Herein, we prepared a 3D SERS active substrate based on heterogeneous and cross-distributed metal structure hybridized with MoS2by in situ synthesizing gold nanoparticles (AuNPs) on MoS2 membrane. The AuNPs-AgNPs/MoS2/P-Si hybrid SERS substrate were characterized by a scanning electron microscope (SEM), a transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) to investigate the character and the content of elements. In virtue of the heterogeneous and cross-distributed structure and ultra-narrow interparticle gap generating strong electric fields enhancement, the ultra-low concentration of probe molecule were detected (the LOD of 10-12 M for R6G and CV, 10-11 M for MG), serving the optimal SERS performance. The excellent uniformity and reproducibility were achieved by the proposed substrate. Moreover, the flexible MoS2/AuNPs-AgNPs/PMMA pyramidal SERS substrate was applied to detect melamine molecule in liquid milk (the LOD reached 10-9 M), which revealed great potential to be an outstanding SERS substrate for biological and chemical detection.

14.
Appl Spectrosc ; 72(11): 1613-1620, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30063384

RESUMO

Surface-enhanced Raman spectroscopy (SERS) is a powerful spectroscopy technique to detect and characterize molecules at a very low concentration level. The two-dimensional (2D) semi-conductor layered material, tin diselenide (SnSe2), is used as a new substrate for enhancing the Raman signals of adsorbed molecules. Three kinds of molecules-Rhodamine 6G (R6G), crystal violet (CV), and methylene blue (MB)-are used as probe molecules to evaluate the SERS performance of SnSe2. The Raman signals of different molecules can be enhanced by SnSe2 nanoplates (NPs). The distinguishable Raman signal of R6G molecules can be obtained for adsorbent concentrations as low as 10-17 mol/L. Based on a detailed analysis of the bandgap structure and opto-electrical properties of SnSe2 NPs, we discuss the process of charge transfer and the Raman enhancement mechanism of SnSe2 NP. The high Raman sensitivity of SnSe2 NPs is related to the charge transfer between molecules and SnSe2, 2D layered structure, and indirect bandgap of few-layered SnSe2. The research results will help to expand the application of SnSe2 in microanalysis, improve the measurement accuracy of SERS, and possibly find use in optoelectronic device integration.

15.
Opt Express ; 26(17): 21626-21641, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30130866

RESUMO

The highly enhanced local electromagnetic field occurring through nanometer gap between the plamonic nanostructures provides the dominant contribution in surface enhancement Raman scattering (SERS) enhancement. Thence, we designed the remarkable SERS platform (AuNPs/WS2@AuNPs hybrids) by introducing bilayer WS2 film as the precise nanospacer. Bilayer WS2 film can realize the facile and tight combination with AuNPs via the thermal decomposition approach. Dense three-dimension (3D) hot spots provided by this hybrid plasmonic nanostructures are responsible for the extremely satisfying SERS performances. Using rhodamine 6G (R6G) as the probe molecules, the AuNPs/WS2@AuNPs hybrids perform the excellent sensitivity with the minimum detectable concentration as low as 10-11 M. Uniform and reproducible SERS signals illustrate that the synthesized SERS hybrids perform the splendid spot-to-spot reproducibility (RSD~5.4%) and substrate-to-substrate reproducibility (RSD~5.7%). The stability of AuNPs and the protection of WS2 film endow this hybrid plasmonic nanostructures with the brilliant anti-oxidation stability. Moreover, the enhanced electric field distribution simulated with the COMSOL software proves the remarkable SERS performance in theory. Therefore, AuNPs/WS2@AuNPs substrate not only widens the SERS research filed of WS2, but also shows vast potential as excellent SERS sensor for practical applicability.

16.
Opt Express ; 26(17): 21784-21796, 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30130880

RESUMO

Various flexible SERS sensors have attracted widespread concern in performing the direct identification of the analytes adsorbed on arbitrary surfaces. Here, a sample method was proposed to integrate plasmonic nanoparticles into polydimethylsiloxane (PDMS) to fabricate flexible substrate for the decoration of silver nanoparticles (AgNPs). The flexible SERS sensor based on AgNPs/AgNPs-PDMS offers highly sensitive Raman detection with enhancement factor up to 8.3 × 109, which can be attributed to the integrative effects from both the increase of the light absorption of the embedded AgNPs in PDMS substrate and the EM enhancement from the adjacent top-top, bottom-bottom and top-bottom AgNPs. After undergoing the cyclic mechanical deformation, the SERS substrate still maintains high mechanical stability and stable SERS signals. However, upon stretching the flexible substrate, there was an amusing phenomenon that SERS signals can be highly increased, which results from that the reduction of lateral nanogaps between top and bottom of the PDMS boundary strengthens the trigger of the plasmon coupling as demonstrated by the simulated result. This result reveals that the tuning and the coupling of the electromagnetic fields can be effectively controlled by the macroscopic mechanical solicitation. That will have an important significance for practical applications in strain-dependent sensors and detectors.

17.
Opt Express ; 26(16): 20649-20660, 2018 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-30119373

RESUMO

The novel fluorescent nanofiber membranes of CsPbX3 (FNMs/CPX, X = Cl, Br, I) with a wide photoluminescence range from 405 nm to 675 nm are fabricated by a one-step electrospinning method in this paper. Owing to the polymer cladding, these FNMs/CPX show much better thermal and humid stability compared to the common CsPbX3 particles, and the corresponding white light-emitting diode prepared by them also exhibits excellent optical properties. Without adopting any complicated processes, this method opens up a brand new way for the perovskite materials using in lighting and display fields.

18.
Nanomaterials (Basel) ; 8(7)2018 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-29996504

RESUMO

As a new atomically layered, two-dimensional material, tin (IV) diselenide (SnSe2) has attracted extensive attention due to its compelling application in electronics and optoelectronics. However, the great challenge of impurities and the preparation of high-quality ultrathin SnSe2 nanoflakes has hindered far-reaching research and SnSe2 practical applications so far. Therefore, a facile chemical vapor deposition (CVD) method is employed to synthesize large-scale ultrathin SnSe2 flakes on mica substrates using SnSe and Se powder as precursors. The structural characteristics and crystalline quality of the product were investigated. Moreover, Raman characterizations indicate that the intensity of A1g peak and Eg peak, and the Raman shift of Eg are associated with the thickness of the SnSe2 nanoflakes. The ultrathin SnSe2 nanoflakes show a strong surface-enhanced Raman spectroscopy (SERS) activity for Rhodamine 6G (R6G) molecules. Theoretical explanations for the enhancement principle based on the chemical enhancement mechanism and charge transfer diagram between R6G and SnSe2 are provided. The results demonstrate that the ultrathin SnSe2 flakes are high-quality single crystal and can be exploited for microanalysis detection and optoelectronic application.

19.
Opt Express ; 26(7): 9017-9026, 2018 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-29715860

RESUMO

Previously, PbS/CdS core/shell quantum dots with excellent optical properties have been widely used as light-harvesting materials in solar cell and biomarkers in bio-medicine. However, the nonlinear absorption characteristics of PbS/CdS core/shell quantum dots have been rarely investigated. In this work, PbS/CdS core/shell quantum dots were successfully employed as nonlinear saturable absorber (SA) for demonstrating a mode-locked Er-doped fiber laser. Based on a film-type SA, which was prepared by incorporating the quantum dots with the polyvinyl alcohol (PVA), mode-locked Er-doped operation with a pulse width of 54 ps and a maximum average output power of 2.71 mW at the repetition rate of 3.302 MHz was obtained. Our long-time stable results indicate that the CdS shell can effectively protect the PbS core from the effect of photo-oxidation and PbS/CdS core/shell quantum dots were efficient SA candidates for demonstrating pulse fiber lasers due to its tunable absorption peak and excellent saturable absorption properties.

20.
Opt Express ; 26(8): 10023-10037, 2018 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-29715945

RESUMO

The development of paper-based SERS substrates that can allow multi-component detection in real-word scenarios is of great value for applications in molecule detection under complex conditions. Here, a multifunctional SERS-based paper sensing substrate has been developed through the uniform patterning of high-density arrays of GO-isolated Ag nanoparticles on the hydrophilic porous cellulose paper strip (GO@AgNP@paper). Wet-chemical synthesis was used to provide the cover of SERS hot spots on any part of the paper, not just limited surface deposition. In virtue of the inherent ability of paper to deliver analytes by the capillary force, the detection ability of the GO@AgNP@paper substrate was greatly promoted, allowing as low as 10-19M R6G detection from microliter-volume (50 µL) samples. For the components with different polarity, the paper substrate can be used as an all-in-one machine to achieve the integration of separation and high-sensitive detection for ultralow mixture components, which improves the practical application value of SERS-based paper devices.

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