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1.
Phys Chem Chem Phys ; 26(14): 10814-10823, 2024 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-38517064

RESUMO

Active control of the surface-enhanced Raman scattering (SERS) enhancement shows great potential for realizing smart detection of different molecules. However, conventional methods usually involve time-consuming structural design or a sophisticated fabrication process. Herein, we reported an electrically tunable field effect transistor (FET) comprising a WOx/MoOx hybrid as the SERS active layer. In the experiment, WOx/MoOx hybrids were first prepared by mixing different molar ratios of WOx and MoOx oxides. Then, R6G molecules were used as Raman reporters, showing that the intensity of the SERS signal observed on the most optimal hybrids (molar ratio = 1 : 3) could be increased by two times as high as that observed on a single WOx or MoOx based substrate, which was ascribed to enhanced charge transfer efficiency by the constructed nano-heterojunction between the WOx and MoOx oxides. Thereafter, a back-gate FET was fabricated on a SiO2/Si substrate, and the most optimal WOx/MoOx hybrid was deposited as the gate channel and the SERS active layer. After that, a series of gate biases (from -15 V to 15 V) were implemented to actively tune the SERS performance of the FET. It is evident that the SERS EF can be further tuned from 2.39 × 107 (-15 V) to 6.55 × 107 (+10 V), which is ∼7.4/4.1 times higher than that observed on the pure WOx device (8.81 × 106) or pure MoOx (1.61 × 107) device, respectively. Finally, the mechanism behind the electrical tuning strategy was investigated. It is revealed that a positive voltage would bend the conduction band down, which increased the electron density near the Fermi level. Consequently, it triggered the resonance charge transfer and significantly improved the SERS performance. In contrast, a negative gate voltage attracted the holes to the Fermi level, which deferred the charge transfer process, and caused the reduction of the SERS enhancement.

2.
Colloids Surf B Biointerfaces ; 237: 113833, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38484444

RESUMO

As a rapid, highly sensitive, and user-friendly technique, surface-enhanced Raman scattering (SERS) has an extraordinary appeal to home self-test of COVID-19 during the post pandemic era. However, most of the existing SERS substrates have been still criticized in stability, repeatability, and sample enrichment. To address these obstacles, a novel non-metallic SERS substrate with porous surfaces and array geometry was developed by in-situ growing ZIF-67 particles on two-dimensional violet phosphorus (VP) matrix. Chemical enhancement was prominently promoted by the synergistic photoinduced charge transfer resonance in the hybrid band structure of the ZIF-67@VP substrate, facilitating a noble metal-similar enhancement factor of 6.11 × 107. The biocompatible ZIF-67@VP porous array with attractive enhancement capability and high anchoring efficiency was further utilized to monitoring SARS-CoV-2 spike protein in practical saliva samples based on a sandwich immunostructure, achieving a limit of detection of 1.7 ng/mL assisted by black phosphorus nanosheets. This nonmetallic immunoassay strategy with exceptional sensitivity and specificity is predicted to extend the utilization of SERS obstacle in daily infectious disease screening.


Assuntos
COVID-19 , Humanos , COVID-19/diagnóstico , Porosidade , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , Imunoensaio , Fósforo , Análise Espectral Raman
3.
Spectrochim Acta A Mol Biomol Spectrosc ; 310: 123962, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38309005

RESUMO

The Surface-enhanced Raman scattering (SERS) is an attractive optical detecting method with high sensitivity and detectivity, however challenges on large-area signal uniformity and complex spectra analysis methods always retards its wide application. Herein, a highly sensitive and uniform SERS detection strategy supported by porous carbon film/WO3-x nanosheets (PorC/WO3-x) based noble-metal-free SERS substrate and deep learning algorithm are reported. Experimentally, the PorC/WO3-x substrate was prepared by high-temperature annealing the PorC/WO3 films under the argon atmosphere. The defect density of the WO3 was controlled by tuning the reducing reaction time during the annealing process. The SERS performance was evaluated by using R6G as the Raman reporter, it showed that the SERS intensity obtained on the substrate with the optimal annealing time of 3 h was about 8 times as high as that obtained on the PorC/WO3 substrate without annealing treatment. And detection limit of 10-7 M and Raman enhancement factor of 106 could be achieved. Moreover, the above optimal SERS substrate was utilized to detect flavonoids of quercetin, 3-hydroxyflavone and flavone, and a deep learning algorithms was incorporated to identify the quercetin. It revealed that quercetin can be accurately detected within the above flavonoids, and lowest detectable concentration of 10-5 M can be achieved.

4.
Spectrochim Acta A Mol Biomol Spectrosc ; 309: 123805, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38154300

RESUMO

Biomimetic materials with fascinating natural micro-nano surface structures offer a good choice for the simple fabrication of surface-enhanced Raman scattering (SERS) substrate. This study presented a novel sodium carboxymethylcellulose (NaCMC)-Ag biomimetic substrate which was fabricated through the reverse replication of micro-nano structures from cantaloupe peel. Particularly, silicon nanoparticles (Si NPs) were doped into this flexible biomimetic substrate in its fabrication process. Abundant electromagnetic "hotspots" could be effectively excited in this Ag densely covered matrix which maintained numerous protrusions as well as vertical and horizontal grooves. Specifically, the doped Si NPs exhibited a robust intrinsic Raman peak, which could be employed as an internal standard to calibrate the target signal. In this regard, the biomimetic substrate with the optimal electromagnetic enhancement and the quantitative calibration capabilities exhibited a high enhancement factor and a remedied linear relationship in the detection. After a perfect uniformity of signal was proved by the corrected SERS mapping, the biomimetic SERS substrate was finally utilized in the practical analysis of methylene blue (MB) and ß-carotene with ultra-low limit of detection, highlighting its importance in practical detection scenarios.

5.
Mater Today Bio ; 23: 100853, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38024845

RESUMO

Engineered scaffolds are used for repairing damaged esophagus to allow the precise alignment and movement of smooth muscle for peristalsis. However, most of these scaffolds focus solely on inducing cell alignment through directional apparatus, often overlooking the promotion of muscle tissue formation and causing reduced esophageal muscle repair effectiveness. To address this issue, we first introduced aligned nano-ferroferric oxide (Fe3O4) assemblies on a micropatterned poly(ethylene glycol) (PEG) hydrogel to form micro-/nano-stripes. Further modification using a gold coating was found to enhance cellular adhesion, orientation and organization within these micro-/nano-stripes, which consequently prevented excessive adhesion of smooth muscle cells (SMCs) to the thin PEG ridges, thereby effectively confining the cells to the Fe3O4-laid channels. This architectural design promotes the alignment of the cytoskeleton and elongation of actin filaments, leading to the organized formation of muscle bundles and a tendency for SMCs to adopt synthetic phenotypes. Muscle patches are harvested from the micro-/nano-stripes and transplanted into a rat esophageal defect model. In vivo experiments demonstrate the exceptional viability of these muscle patches and their ability to accelerate the regeneration of esophageal tissue. Overall, this study presents an efficient strategy for constructing muscle patches with directional alignment and muscle bundle formation of SMCs, holding significant promise for muscle tissue regeneration.

6.
ACS Appl Mater Interfaces ; 15(35): 42026-42036, 2023 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-37612785

RESUMO

The significant boost in surface-enhanced Raman scattering (SERS) by the chemical enhancement of semiconducting oxides is a pivotal finding. It offers a prospective path toward high uniformity and low-cost SERS substrates. However, a detailed understanding of factors that influence the charge transfer process is still insufficient. Herein, we reveal the important role of defect-induced band offset and electron lifetime change in SERS evolution observed in a MoO3 oxide semiconductor. By modulating the density of oxygen vacancy defects using ultraviolet (UV) light irradiation, SERS is found to be improved with irradiation time in the first place, but such improvement later deteriorates for prolonged irradiation even if more defects are generated. Insights into the observed SERS evolution are provided by ultraviolet photoelectron spectroscopy and femtosecond time-resolved transient absorption spectroscopy measurements. Results reveal that (1) a suitable offset between the energy band of the substrate and the orbitals of molecules is facilitated by a certain defect density and (2) defect states with relatively long electron lifetime are essential to achieve optimal SERS performance.

7.
Spectrochim Acta A Mol Biomol Spectrosc ; 300: 122971, 2023 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-37295203

RESUMO

Surface enhanced Raman scattering (SERS) is a rapid and non-destructive spectral detection technique, and has been widely implemented on trace-level molecule detection. In this work, a hybrid SERS substrate constructed by porous carbon film and silver nanoparticles (PCs/Ag NPs) was developed and then used for imatinib (IMT) detection in bio-environment. The PCs/Ag NPs was prepared by direct carbonizing the gelatin-AgNO3 film in the air atmosphere, and an enhancement factor (EF) of 106 was achieved with R6G as the Raman reporter. Hereafter, this SERS substrate was used as the label-free sensing platform to detect the IMT in the serum, and the experimental results indicate that the substrate is conducive to eliminating the interference from the complex biological molecules in the serum, and the characteristic Raman peaks belonging to IMT (10-4 M) are accurately resolved. Furthermore, the SERS substrate was used to trace the IMT in the whole blood, the trace of ultra-low concertation of IMT is rapidly discovered without any pretreatment. Thus, this work finally suggests that the proposed sensing platform provides a rapid and reliable method for IMT detection in the bio-environment and offers a potential for its application in therapeutic drug monitoring.


Assuntos
Nanopartículas Metálicas , Nanopartículas Metálicas/química , Mesilato de Imatinib , Prata/química , Porosidade , Carbono , Análise Espectral Raman/métodos
8.
ACS Omega ; 8(21): 18523-18529, 2023 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-37273592

RESUMO

Surface-enhanced Raman scattering (SERS) is a spectral detection technology with high sensitivity and detectivity and can be used to detect the fingerprint information of the molecules with ultralow concentration. Herein, a kind of immunostructure constructed by Ag nanoparticle/porous carbon (Ag NP/PorC) films as the immunosubstrate and Ag NCs as the immunoprobes was presented for ultralow level prostate-specific antigen (PSA) detection. Experimentally, the Ag NP/PorC film was first prepared with a facile method by carbonizing the gelatin-AgNO3 film in air, and Ag NCs were synthesized by the hydrothermal method. Then, the Ag NP/PorC film was modified by PSA antibodies as the substrate, while Ag NCs were decorated by R6G and PSA antibodies for probes. The sandwiched SERS detection embodiment was constructed by the immunoreaction between the PSA and PSA antibody predecorated on the substrate and probes. Our results show that the proposed SERS-type immunoassay is highly sensitive and selective to a wide range of PSA concentrations from 10-5 to 10-12 g/mL. Thereafter, it was also implemented to detect the PSA level in human serum, and the results successfully reproduce the PSA levels as those measured by the chemiluminescence method with a recovery rate above 90%. All in all, this SERS-type immunoassay provides a promising method for the early diagnosis of prostate cancer.

9.
Colloids Surf B Biointerfaces ; 227: 113338, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37167693

RESUMO

To improve the curability of cancer patients, it is essential to propose an early diagnosis technology with ultra-high sensitivity and reliable biocompatibility. Herein, a sophisticated nonmetallic SERS-based immunosensor, comprised by a MoS2 @Fe3O4 nanoflower-based immunoprobe with magnetism and a black phosphorus (BP) nanosheet-based immunosubstrate, was proposed for the specific in-situ monitoring of ferritin (FER). The sandwich immunosensor was endowed with an excellent SERS performance mainly ascribed to a synergistic chemical enhancement as well as an additional electrostatic adsorption effect, achieving a limit of detection down to 7.3 × 10-5 µg/mL. Particularly, all the Raman label, target FER, and anti-FER could be completely degraded within 70 min under visible light irradiation owing to the favorable photocatalytic activities of MoS2 and BP which could be then effectively separated and collected with the assistance of an external magnet. Such a recyclable nonmetallic immunosensor holds great potential and practicality in the clinical screening of cancer.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Humanos , Molibdênio , Imunoensaio , Ouro , Fenômenos Magnéticos , Análise Espectral Raman
10.
Spectrochim Acta A Mol Biomol Spectrosc ; 299: 122801, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37187146

RESUMO

Surface-enhanced Raman scattering (SERS) technology enables to satisfy the increasing demand of clinical drug monitoring due to the superiority of fingerprint recognition, real-time response, and nondestructive collection. Here, a novel graphitic carbon nitride (g-C3N4)/ molybdenum disulfide (MoS2)/Ag composite substrate with a 3D surface structure was successfully developed for the recyclable detection of gefitinib in serum. Attributed to the uniform and dense "hotspots" on the shrubby active surfaces in conjunction with the potential synergistic chemical enhancement of g-C3N4/MoS2 heterosystem, a remarkable SERS sensitivity with an attractive enhancement factor value of 3.3 × 107 was demonstrated. Meanwhile, a type-II heterojunction between g-C3N4 and MoS2 enabled more efficient diffusion of photogenerated e--h+ pairs assisted by the localized surface plasmon resonance of Ag NPs, which contributed to the reliable recyclable detection of gefitinib. The ultra-low limit of detection at 10-5 mg/mL and high recycling rates of gefitinib beyond 90% in serum were successfully realized. The results demonstrated the as-prepared SERS substrate has tremendous potential to be untilized for in-situ drug diagnostics.


Assuntos
Nanopartículas Metálicas , Molibdênio , Gefitinibe , Molibdênio/química , Ressonância de Plasmônio de Superfície , Análise Espectral Raman/métodos , Nanopartículas Metálicas/química
11.
Phys Chem Chem Phys ; 25(15): 10820-10826, 2023 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-37013421

RESUMO

Surface-enhanced Raman scattering (SERS) is a non-destructive spectral analysis technique. It has the virtues of high detectivity and sensitivity, which have been extensively studied for low-trace molecule detection. In the choices of SERS substrate materials, low-cost and abundant reserved transition metal oxide/chalcogenide materials have been regarded as promising substitutes for noble metals; however, their inferior SERS enhancement severely limits their practical application. Herein, a class of MoS2/MoOx heterostructures have been demonstrated with significantly improved SERS performance. Experimentally, MoS2/MoOx heterostructures were prepared by precisely controlled oxidation of MoS2 nanospheres in an ultraviolet-ozone environment, and the optimal SERS substrate was obtained with 14 hours of ultraviolet-ozone irradiation. SERS measurements revealed superior SERS performance with a detection limit of 10-7 M (rhodamine 6G) and an enhancement factor of 7.477 × 106 (R6G@10-7 M) could be obtained. Finally, the intuitive SERS enhancement mechanism was investigated via energy band analysis. It revealed that the constructed heterostructures enhanced the electron-hole separation, and the electrons were successively transferred to the analytes and significantly promoted the molecular polarizability, improving the SERS performance.

12.
Food Chem ; 418: 136011, 2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-37001358

RESUMO

Typically, for accurate quantitative tests of molecules, considering the actual solute concentration in the environment with different water activities (Aws) is essential. Accordingly, for effective detection of food substances, this paper proposes a non-destructive pluggable sensor to capture and monitor four free purines based on surface-enhanced Raman scattering characteristics such as sensitivity, uniformity, repeatability, and stability. In particular, we investigate the impact of Aw on the evaluation of purine detection and its deviation corrections. Furthermore, the recoveries of purine from three food products, including fish (Aw: 0.99), ham (Aw: 0.91), and bacon (Aw: 0.73), are subsequently explored to validate the reliability of the proposed method. The results indicate that the proposed non-destructive pluggable sensor performs better when the Aw is considered. Therefore, this strategy for achieving more reliable quantitative detection by rectifying deviations based on the Aw can significantly help monitor food quality.


Assuntos
Nanopartículas Metálicas , Análise Espectral Raman , Animais , Limite de Detecção , Purinas , Reprodutibilidade dos Testes , Análise Espectral Raman/métodos , Análise de Alimentos , Alimentos
13.
Analyst ; 148(8): 1752-1763, 2023 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-36951197

RESUMO

Owing to its promising biocompatibility and reliable sensitivity, semiconductor-guided surface-enhanced Raman scattering (SERS) technology has aroused widespread concern in clinical immunoassays. Herein, the well-improved light capture capability of MoS2 with a novel three-dimensional (3D) flower-like morphology was combined with the synergistic chemical enhancement from a MoS2@red phosphorus (RP) hybrid system, facilitating an attractive non-metallic SERS-based detection of ferritin in serum. Owing to the remarkable enhancement factors of both the immunoprobe and immunosubstrate, which were comparable to noble metal, an extremely low limit detection of 11.5 pg mL-1 was achieved in the absence of fluorescence interference. In particular, the trace ferritin in the clinical serum sample was successfully monitored, demonstrating superior sensitivity to the traditional chemiluminescent method. Overall, this study convincingly revealed the feasibility and reliability of SERS-based immunoassays induced by biocompatible semiconductors, which has opened a new way to implement the detection and tracking of biomarkers in the human body.


Assuntos
Ouro , Molibdênio , Humanos , Reprodutibilidade dos Testes , Imunoensaio/métodos , Análise Espectral Raman/métodos
14.
Sci Total Environ ; 872: 162277, 2023 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-36801332

RESUMO

The growing persistence of harmful ion or drug molecular residues has always been considered as a matter of concern due to its importance in biological and environmental processes, which requires taking measures to maintain environmental health sustainably and effectively. Inspired by the multi-system and visual quantitative detection of nitrogen-doped carbon dots (N-CDs), we develop a novel cascade nano-system based on dual emission carbon dots for on-site visual quantitative detection of curcumin and fluoride ion (F-). Herein, tris (hydroxymethyl) aminomethane (Tris) and m-dihydroxybenzene (m-DHB) are elected as reaction precursors to synthesize dual-emission N-CDs by a one-step hydrothermal method. The obtained N-CDs exhibit dual emission peaks at 426 nm (blue) and 528 nm (green) with quantum yields of 53 % and 71 %, respectively. Then, trace curcumin and F- intelligent off-on-off sensing probe is formed by taking advantage of the activated cascade effect. As for the occurrence of inner filter effect (IFE) and fluorescence resonance energy transfer (FRET), the green fluorescence of N-CDs quenches remarkably, called as OFF initial state. Then the curcumin-F- complex leads to the hypochromatic shift of the absorption band from 532 to 430 nm, which activates the green fluorescence of N-CDs, named as ON state. Meanwhile, the blue fluorescence of N-CDs is quenched due to the FRET, called as OFF terminal state. This system shows good linear relationships from 0 to 35 µM and 0 to 40 µM with low detection limits of 29 nM and 42 nM for curcumin and F- ratiometric detection, respectively. Moreover, a smartphone-assisted analyzer is developed for on-site quantitative detection. Furthermore, we design a logic gate for logistics information storage, which proves the possibility of a logic gate based on N-CDs in practical application. Thus, our work will provide an effective strategy for environmental quantitative monitoring and information storage encryption.


Assuntos
Curcumina , Pontos Quânticos , Pontos Quânticos/química , Carbono/química , Nitrogênio/química , Smartphone , Espectrometria de Fluorescência/métodos , Corantes Fluorescentes
15.
Food Chem ; 411: 135514, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-36724609

RESUMO

The design of intelligent and real-time sensing devices is significant in the medical drug monitoring field, but it is still highly challenging. Here, ratiometric fluorescent detections of ofloxacin (OFL) and its L-isomer levofloxacin (LEV) constructed from tri-doped graphene quantum dots (T-GQDs) are reported, and the detection limits reach as low as 46/67 nM toward OFL/LEV due to the intermolecular electron transfer (intermolecular ET) effect. After adding OFL/LEV, the generation of electrostatic bond provides a channel for the intermolecular ET from the edge of T-GQDs to OFL/LEV, resulting in the fluorescence quenching at 414 nm and the fluorescence promoting at 498 nm. Furthermore, a smartphone can be used for the visual and quantitative detection of OFL and LEV by identifying the RGB values of test paper and drink samples. This work not only reveals the physics mechanism of ratiometric detection, but also develops a convenient smartphone diagnostic for OFL and LEV.


Assuntos
Grafite , Pontos Quânticos , Ofloxacino , Corantes Fluorescentes/química , Grafite/química , Pontos Quânticos/química , Elétrons , Espectrometria de Fluorescência/métodos
16.
Anal Methods ; 15(10): 1261-1273, 2023 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-36846932

RESUMO

Two essential factors in powerful surface-enhanced Raman spectroscopy analysis of trace pesticide residues are viz., high sensitivity and efficient sampling. Herein, owing to elastic properties, a stretched Ag nanowire (Ag NW)-tape under the strain of 15% formed a wrinkled structure with periodic microridges and microgrooves, where abundant nanogaps were generated by the aggregated Ag NWs. Compared with the unstretched Ag NW-tape substrate, an appreciable signal enhancement of the modified 4-mercaptobenzoic acid (4-MBA) molecules with a ratio of 2.6 was discerned from the sophisticated SERS substrate due to the electromagnetic enhancement induced by the relatively high density of "hot spots" around the Ag NW aggregates. The as-fabricated Ag NW-tape substrate performed admirably in detecting 4-MBA and demonstrated an enhancement factor of 1.16 × 106. Moreover, for the in situ detection of tetramethylthiuram disulfide, thiabendazole, and their mixture, the relatively high recovery rates of over 88% were favorably realized by the Ag NW-tape substrate with superior sensitivity, distinct flexibility, and adhesiveness. This fascinating SERS substrate, dependent on the flexible and adhesive Ag NW-tape, is promising for application in SERS analysis of trace residues on various practical surfaces.

17.
Biosens Bioelectron ; 227: 115160, 2023 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-36827796

RESUMO

Recently, non-metallic SERS-based immunoassay has attracted much attention due to its attractive chemical enhancement (CM), chemical stability, and biocompatibility. Herein, metallic (1T)-semiconductor (2H) mixed-phase magnetic molybdenum disulfide (MoS2) was rationally developed and combined with two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets to realize a SERS-based recyclable immunoassay of CA125. The Fe3O4 core promoted the reliable stacking of MoS2 nanoflakes into a flower-like shape with fully-exposed active surface. Particularly, the existence of 1T phase facilitated a noble-metal-comparable SERS activity due to the high electron density-induced charge transfer process with elevated efficiency. Moreover, a conversion from bulk to 2D nanosheet was swimmingly achieved for g-C3N4 via acid etching, whose large surface area full of active electrons and functional groups triggered an enhancement factor (EF) of 7.8 × 106. Based on a typical sandwich immunostructure, a limit of detection (LOD) as 4.96 × 10-4 IU/mL was demonstrated for CA125 in a recyclable process. Finally, such an immunosensor was employed to analyze clinical samples, indicating its prodigious potentiality in the early recognition and monitoring of cancer.


Assuntos
Técnicas Biossensoriais , Molibdênio , Imunoensaio , Antígeno Ca-125 , Elétrons
18.
Anal Chim Acta ; 1239: 340706, 2023 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-36628714

RESUMO

The appearance of multi-drug resistant Escherichia coli makes the combination of tetracyclines (TCs) and quercetin (QCT) more common to fight stubborn bacterial infections so that the effective detections of TCs and QCT are essential and necessary. Here, a novel fluorescence probe for differentiating TCs and QCT is developed based on the nitrogen and copper co-doped carbon dots (N, Cu-CDs). The N, Cu-CDs are prepared from ethylene diamine tetraacetic acid (EDTA) and anhydrous copper chloride as precursors through hydrothermal process and exhibit bright blue fluorescence with excellent optical stability. With the presence of four tetracyclines (DOX, TC, CTC and OTC), the fluorescence intensity of N, Cu-CDs is quenched directly due to the internal filtration effect (IFE), and the detection limit obtained through single-signal fluorescence sensing is as low as 23.8 nM for DOX, 37.2 nM for TC, 43.8 nM for OTC and 28.8 nM for CTC. More remarkably, three dimensional ratiometric fluorescence probe for detecting QCT is proposed based on the appearance of another emission at (410 nm, 490 nm) due to electron transform (ET) process. This new method shows a good linear relationship in the range of 10-100 µM with a low detection limit of 59.3 nM. Furthermore, a dual-channel fluorescence sensing platform based on microfluidics paper-based analytical devices (µPADs) is developed for simultaneously visual discrimination of TCs (DOX is chosen as the typical detecting model for TCs) and QCT. This investigation provides a new way for the development of CDs as multifunction fluorescence probes.


Assuntos
Pontos Quânticos , Tetraciclinas , Espectrometria de Fluorescência/métodos , Quercetina , Carbono , Cobre , Antibacterianos , Corantes Fluorescentes , Transferência de Energia
19.
Opt Express ; 30(17): 30430-30440, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-36242147

RESUMO

On-chip nonvolatile photonic switches enabled by phase change materials (PCMs) are promising building blocks for power-efficient programmable photonic integrated circuits. However, large absorption loss in conventional PCMs (such as Ge2Sb2Te5) interacting with weak evanescent waves in silicon waveguides usually leads to high insertion loss and a large device footprint. In this paper, we propose a 2×2 photonic switch based on two-mode interference in a multimode slot waveguide (MSW) with ultralow loss Sb2S3 integrated inside the slot region. The MSW supports two lowest order TE modes, i.e., symmetric TE00 and antisymmetric TE01 modes, and the phase of Sb2S3 could actively tune two-mode interference behavior. Owing to the enhanced electric field in the slot, the interaction strength between modal field and Sb2S3 could be boosted, and a photonic switch containing a ∼9.4 µm-long Sb2S3-MSW hybrid section could effectively alter the light transmission between bar and cross ports upon the phase change of Sb2S3 with a cross talk (CT) less than -13.6 dB and an insertion loss (IL) less than 0.26 dB in the telecommunication C-band. Especially at 1550 nm, the CT in the amorphous (crystalline) Sb2S3 is -36.1 dB (-31.1 dB) with a corresponding IL of 0.073 dB (0.055 dB). The proposed 2×2 photonic switch is compact in size and compatible with on-chip microheaters, which may find promising applications in reconfigurable photonic devices.

20.
Spectrochim Acta A Mol Biomol Spectrosc ; 283: 121732, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-35985232

RESUMO

Strapping plasmonic substrate with a reliable ability to anchor molecules and achieve reproducible result provides trustworthy opportunities for flourishing surface-enhanced Raman scattering (SERS) technique. Herein, a facile controllable in-situ anisotropic growth strategy was exploited to anchor gold nanowires (Au NWs) onto two-dimensional g-C3N4 nanosheets (g-C3N4/Au NWs), facilitating a sensitive and recyclable SERS sensor for gaseous analytes. Benefiting from the attractive enrichment effect of the brush-like surface formed by numerous small Au NWs as well as their rich nanotips-mediated enhancement capability, the hybrid substrate showed an outstanding performance in SERS-based detection of trace 4-Aminothiophenol (4-ATP) molecules, demonstrating a monitoring limitation down to 10-8 M even in atmosphere. Satisfyingly, under visible light illumination, the efficient green photocatalytic ability derived from the g-C3N4 supporting matrix rendered reusable capability for the substrate, whose SERS signal was kept at a persistent high level throughout 6 cycles. Attributed to the narrow line width of SERS spectrum, the 4-ATP assay under the interference of 2-naphthalenethiol (2-NAT) was acquired in gas phase and the dependable recovery rates from 85.4 to 93.9% were confirmed as well. Thanks to the intriguing features including excellent sensitivity and recyclability, the g-C3N4/Au NWs substrate proposed here will pave the way toward the potential application of SERS technique in multiplexed gaseous detection.


Assuntos
Nanopartículas Metálicas , Nanofios , Trifosfato de Adenosina , Gases , Ouro/química , Nanopartículas Metálicas/química , Nanofios/química , Análise Espectral Raman/métodos
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