Enhancement Factor Research Articles

Rapid detection of melamine by DNA Walker mediated SERS sensing technique based on signal amplification function.

A new method is proposed for detecting typical melamine dopants in food using surface-enhanced Raman scattering (SERS) biosensing technology. Melamine specific aptamer was used as the identification probe, and gold magnets (AuNPs@MNPs) and small gold nanoparticles (AuNPs@MBA) were used as the basis for Raman detection. The Raman signal of the detection system can directly detect melamine quantitatively. Under optimized conditions, the detection of melamine was carried out in the low concentration range of 0.001-500mg/kg, the enhancement factor (EF) was 2.3 × 107, and the detection limit was 0.001mg/kg. The method is sensitive and rapid, and can be used for the rapid detection of melamine in the field environment.

A breakthrough in phytochemical profiling: ultra-sensitive surface-enhanced Raman spectroscopy platform for detecting bioactive components in medicinal and edible plants.

A perennial challenge in harnessing the rich biological activity of medicinal and edible plants is the accurate identification and sensitive detection of their active compounds. In this study, an innovative, ultra-sensitive detection platform for plant chemical profiling is created using surface-enhanced Raman spectroscopy (SERS) technology. The platform uses silver nanoparticles as the enhancing substrate, excess sodium borohydride prevents substrate oxidation, and methanol enables the tested molecules to be better adsorbed onto the silver nanoparticles. Subsequently, nanoparticle aggregation to form stable "hot spots" is induced by Ca2+, and the Raman signal of the target molecule is strongly enhanced. At the same time, deuterated methanol was used as the internal standard for quantitative determination. The method has excellent reproducibility, RSD ≤ 1.79%, and the enhancement factor of this method for the detection of active ingredients in the medicinal plant Coptis chinensis was 1.24 × 109, with detection limits as low as 3 fM. The platform successfully compared the alkaloid distribution in different parts of Coptis chinensis: root > leaf > stem, and the difference in content between different batches of Coptis chinensis decoction was successfully evaluated. The analytical technology adopted by the platform can speed up the determination of Coptis chinensis and reduce the cost of analysis, not only making better use of these valuable resources but also promoting development and innovation in the food and pharmaceutical industries. This study provides a new method for the development, evaluation, and comprehensive utilization of both medicinal and edible plants. It is expected that this method will be extended to the modern rapid detection of other medicinal and edible plants and will provide technical support for the vigorous development of the medicinal and edible plants industry.

Enhancing Multi-Spectral Fingerprint Sensing for Trace Explosive Molecules with All-Silicon Metasurfaces.

Spectroscopy is a powerful tool to identify the specific fingerprints of analytes in a label-free way. However, conventional sensing methods face unavoidable barriers in analyzing trace-amount target molecules due to the difficulties of enhancing the broadband molecular absorption. Here, we propose a sensing scheme to achieve strong fingerprint absorption based on the angular-scanning strategy on an all-silicon metasurface. By integrating the mid-infrared and terahertz sensing units into a single metasurface, the sensor can efficiently identify 2,4-DNT with high sensitivity. The results reveal that the fingerprint peak in the enhanced fingerprint spectrum is formed by the linked envelope. It exhibits a significant enhancement factor exceeding 64-fold in the terahertz region and more than 55-fold in the mid-infrared region. Particularly, the corresponding identification limit of 2,4-DNT is 1.32 µg cm-2, respectively. Our study will provide a novel research idea in identifying trace-amount explosives and advance practical applications of absorption spectroscopy enhancement identification in civil and military security industries.

A tailored dual core-shell magnetic SERS substrate with precise shell-thickness control for trace organophosphorus pesticides residues detection

For addressing the challenges of strong affinity SERS substrate to organophosphorus pesticides (OPs), herein, a rapid water-assisted layer-by-layer heteronuclear growth method was investigated to grow uniform UiO-66 shell with controllable thickness outside the magnetic core and provide abundant defect sites for OPs adsorption. By further assembling the tailored Au@Ag, a highly sensitive SERS substrate Fe3O4-COOH@UiO-66/Au@Ag (FCUAA) was synthesized with a SERS enhancement factor of 2.11 × 107. The substrate's suitability for the actual vegetable samples (cowpeas and peppers) was confirmed under both destructive and non-destructive detection conditions, showing a strong SERS response to fenthion and triazophos, with limits of detection of 1.21 × 10-5 and 2.96 × 10-3 mg/kg in the vegetables under destructive conditions, and 0.13 and 1.39 ng/cm2 for non-destructive detection, respectively. The FCUAA substrate had high SERS performance, effective adsorption capability for OPs, and demonstrated good applicability, thus exhibiting great potential for rapid detection of trace OPs residues in the food industry.

Broadband and high-enhancement-factor integrated long-wave infrared sensor using the photonic crystal assisted subwavelength grating waveguide

In this paper, a broadband and high-enhancement-factor integrated long-wave infrared sensor using the photonic crystal assisted subwavelength grating waveguide is presented, optimized, and analyzed in detail. By reasonably designing the structure and optimizing the corresponding parameters, the dispersion relationship can be adjusted to realize a relatively flat band and the slow-light effect can be introduced to improve the interaction between light and matter so that large and stable slow-light enhancement factors are obtained in a wide wavelength range, achieving high-performance detection of multiple types of matter. For the optimized sensor, the operating bandwidth from 7.65142 to 7.71125 µm is realized. When C2H2, HNO3, CH4, H2O2, or N2O is treated as the target matter, the corresponding slow-light enhancement factor at 7.677 µm, 7.661 µm, 7.670 µm, 7.7 µm, or 7.705 µm is, respectively, 4.3405, 4.3432, 4.3194, 5.1584, or 5.9745; the relevant sensitivity is 0.2394Wmol−1L, 0.3466Wmol−1L, 0.3639Wmol−1L, 0.2058Wmol−1L, or 0.4791Wmol−1L; and the minimum detectable concentration is 0.6032 ppb, 0.4164 ppb, 0.3966 ppb, 0.7019 ppb, or 0.3010 ppb.

Innovative Synthesis of Adhesive-Assisted and Recyclable Fe3O4@PD-Ag Photomagnetic Nanocomposites as SERS probes for Ultrasensitive Thiram Detection on Fruit Peels

Surface-enhanced Raman spectroscopy (SERS) with enormous advantages has emerged as a powerful tool for both highly sensitive structural detection of analytes and various imaging applications. A notable advancement in the realm of multifunctional SERS substrates is the integration of magnetic nanoparticles endowed with magnetic manipulation capabilities and noble metal nanoparticles exhibiting plasmonic resonance properties. This synergistic combination offers substantial practical benefits for trace analysis across diverse fields. In this paper, a new paradigm of Fe3O4@PEI-DTC-Ag (Fe3O4@PD-Ag) photomagnetic nanocomposites based on magnetic Fe3O4 nanoparticles (NPs), the noble metal silver quantum dots (Ag QDs) and the adhesive layer polyethyleneimine dithiocarbamate (PEI-DTC) for convenient recycling and ultrasensitive SERS detection was developed by engineering hydrothermal and seed-growth methods. The SERS performance of the Fe3O4@PD-Ag substrates with varying amounts of Ag was evaluated by detecting 4-aminothiophenol (4-ATP). Among the tested samples, Fe3O4@PD-Ag-4 with a silver solution volume of 200 ml exhibited the optimal performance, showcasing an enhancement factor (EF) of 4.418 × 105. Moreover, the relative standard deviations (RSDs) were calculated to be less than 11.5 %, demonstrating the SERS substrates exhibit good uniformity and spectral reproducibility. Of note, the SERS substrate has demonstrated successful trace detection of thiram molecules, achieving a limit of detection (LOD) of up to 10-9 M. The intensity of SERS signals shows a linear correlation with the logarithm of thiram concentration, ranging from 10-4 to 10-9 M, thus providing compelling evidence for quantitative detection. Importantly, the Fe3O4@PD-Ag-4 SERS substrate also showcases outstanding performance for detecting thiram in real food, underscoring its significant potential for application in food safety monitoring.

Constraining nucleon effective masses with flow and stopping observables from the SπRIT experiment

Properties of the nuclear equation of state (EoS) can be probed by measuring the dynamical properties of nucleus-nucleus collisions. In this study, we present the directed flow (v1), elliptic flow (v2) and stopping (VarXZ) measured in fixed target Sn + Sn collisions at ▪ with the SπRIT Time Projection Chamber. We perform Bayesian analyses in which EoS parameters are varied simultaneously within the Improved Quantum Molecular Dynamics-Skyrme (ImQMD-Sky) transport code to obtain a multivariate correlated constraint. The varied parameters include symmetry energy, S0, and slope of the symmetry energy, L, at saturation density, isoscalar effective mass, ms⁎/mN, isovector effective mass, mv⁎/mN and the in-medium cross-section enhancement factor η. We find that the flow and VarXZ observables are sensitive to the splitting of proton and neutron effective masses and the in-medium cross-section. Comparisons of ImQMD-Sky predictions to the SπRIT data suggest a narrow range of preferred values for ms⁎/mN, mv⁎/mN and η.

EC-QCL sensing system–incorporated adaptive baseline correction algorithm for simultaneous detection of multiple gas components

In this study, we presented a multi-gas sensor developed by employing an external cavity quantum cascade laser (EC-QCL)-integrated adaptive baseline correction algorithm for the simultaneous detection of ammonia (NH3), ozone (O3), and carbon dioxide (CO2). The EC-QCL sensing system was selected due to its high wavelength resolution and wide tuning range (1033–1068 cm−1), enabling the simultaneous measurement of multi-gases. The system complexity was effectively decreased and the superimposed noise was avoided by employing an adaptive baseline correction algorithm based on differential transformation and B-Spline approximation (ADTBA), which enabled the resolution of the uneven EC-QCL baseline signals. The performance validation of the ADTBA algorithm by comparing it with the conventional polynomial fitting for detecting the spectra of NH3, O3, and CO2 showed that the former outperformed the latter. The results showed a sensitivity enhancement factor of 3.7, indicating that the newly developed algorithm can generate a high-quality gas absorption spectrum. Allan deviation analysis of the system's responsiveness revealed an averaging time of 120 s resulting in sensitivities of 1.3, 26.7, and 37.0 ppm for NH3, O3, and CO2, respectively.

Multicomponent image-based modeling of water flow in heterogeneous wet shale nanopores

Shale contains abundant multicomponent nanopores with different wettability. Water flow in multicomponent nanoporous systems is still unclear due to the effects of mineral composition, complex pore-throat topology, and heterogeneous wettability. This work develops a contact angle-dependent numerical model for nanoconfined water flow considering heterogeneous wettability, slip effect, and effective viscosity. Water flow in single-component (i.e., clay, organic, inorganic) and multicomponent nanoporous media reconstructed utilizing image fusion techniques is systematically investigated. Results show that the enhancement factor increases exponentially, and the tortuosity increases with increasing contact angle. Water flow is inhibited under strongly hydrophilic conditions, with the enhancement factor linearly negatively correlated with specific surface area. Under hydrophobic conditions, the throat aspect ratio is inversely related to the enhancement factor, which is suppressed in quasi-circular pores. Water flow is restricted in clay pores and enhanced in organic pores due to the differences in pore-throat size and wettability. For the heterogeneous wetting system, the global flow is enhanced compared to no slip and homogeneous wetting conditions. Affected by clay and organic pores with different wettability, the velocity is non-uniformly enhanced, and the effect diminishes as water flows. This work provides a numerical perspective for water flow in heterogeneous wet nanoporous systems.

Fabrication of amino- and hydroxyl dual-functionalized magnetic microporous organic network for extraction of zearalenone from traditional Chinese medicine prior to the HPLC determination

Efficient enrichment of trace zearalenone (ZEN) from the complex traditional Chinese medicine (TCM) samples is quite difficult, but of great significance for TCM quality control. Herein, we reported a novel magnetic solid phase extraction (MSPE) strategy for ZEN enrichment using the amino- and hydroxyl dual-functionalized magnetic microporous organic network (Fe3O4@MON-NH2-OH) as an advanced adsorbent combined with the high-performance liquid chromatography (HPLC) determination. Efficient extraction of ZEN was achieved via the possible hydrogen bonding, hydrophobic, and π-π interactions between Fe3O4@MON-NH2-OH and ZEN. The adsorption capacity of Fe3O4@MON-NH2-OH for ZEN was 215.0 mg g−1 at the room temperature, which was much higher than most of the reported adsorbents. Under the optimal condition, the developed Fe3O4@MON-NH2-OH-MSPE-HPLC method exhibited wide linear range (5–2500 μg L−1), low limits of detection (1.4–35 μg L−1), less adsorbent consumption (5 mg), and large enhancement factor (95) for ZEN. The proposed method was successfully applied to detect trace ZEN from 10 kinds of real TCM samples. Conclusively, this work demonstrates the Fe3O4@MON-NH2-OH can effectively extract trace ZEN from the complex TCM matrices, which may open up a new way for the application of MONs in the enrichment and extraction of trace contaminants or active constituents from the complex TCM samples.

Flexible SERS sensor based on the photodecoration of Au-NPs on Co3O4 NWs/carbon fiber cloth for the ultrasensitive detection of methylene blue in the curved fish surfaces

BackgroundDevelopment of flexible platform via the surface-enhanced Raman spectroscopy (SERS) technique has gained enormous attention as a low-cost and portable substrate for a wide range application. In particular, the fabrication of semiconductors and tuning their surface morphologies with plasmonic nanoparticles are considered to be a fascinating strategy to create numerous hotspots to yield superior SERS enhancement. ResultsThis work involved fabricating a flexible SERS active substrate using the carbon fiber cloth (CFC), which is hydrothermally grown with cobalt oxide nanowires (Co3O4 NWs) and photodecorated with plasmonic gold nanoparticles (Au-NPs) for the ultrasensitive detection of organic dye, methylene blue (MB). The proposed substrate exhibits high enhancement factor (4.5 × 1010), low limit of detection (1.42 × 10−10 M), good uniformity (6.27 %), superior reproducibility (6.30 %) and demonstrate an excellent mechanical strength up to 40 cycles towards the MB detection. The residues of the MB are directly detected on the fish surfaces by adopting a facile swab-sampling technique. Additionally, the proposed flexible SERS sensor exhibit a successful photodegradation of MB at 90 min under UVC light irradiation. Significance and noveltyThe proposed flexible SERS methodology for detecting MB in the curved surfaces exhibited a superior SERS enhancement owing to the synergistic effect raised from the Co3O4 NWs (chemical enhancement) and Au NPs (electromagnetic enhancement). These findings indicate that the CFC-based flexible SERS sensor is a promising candidate for detecting various organic pollutants in real-time and on non-planar surfaces.

Wet torrefaction of biomass waste into high quality hydrochar and value-added liquid products using different zeolite catalysts

Wet torrefaction (WT) proves to be a highly efficient pretreatment method for biomass waste, resulting in the production of hydrochar and valuable liquid products. In this study, a groundbreaking chemocatalytic approach is introduced, employing various zeolite catalysts (H-ZSM-5, H-Beta, H–Y, H-USY, and H-Mordenite) in a batch reactor under a nitrogen atmosphere. This method enables the simultaneous one-pot production of levulinic acid (LA) and/or bio-ethanol during the WT process of wood cellulose pulp residue (WCPR), ultimately yielding high-quality solid fuel. The WT process involves at 220 and 260 °C, H2O/WCPR = 10, and torrefaction time at 15, 30 and 60 min. The study identifies that at 220 °C and 15 min, as the optimal temperature and time, for bio-ethanol production, achieving a selectivity of 59.0 % with the H–Y catalyst, while the highest amount of bio-ethanol (75.6 %) was detected in presence of H-USY zeolite at 260 °C after 60 min. In addition, it was found the formation of relatively high amount of LA (62.0 %) at 220 °C after 60 min but using the H-ZSM-5 catalyst. For the WT + Mordenite sample (220 °C, 60 min), the highest carbon content of 71.5 % is achieved, resulting in the higher heating value (HHV) of 27.3 MJ/kg, an enhancement factor of 1.36, and carbon enrichment of 1.48, with the sequence of element removal during WT prioritized as DO > DH > DC and the weight loss of 68 %. Finally, the reaction mechanism was proposed to elucidate the formation of liquid products after WT of WCPR with participation of zeolite catalysts. The main pathway involving the direct conversion of cellulose into hydroxyacetone, followed by the subsequent generation of ethanol through the C–C cleavage of hydroxyacetone while LA formed via well-known route which includes cellulose hydrolysis to form glucose, conversion to 5-HMF and the subsequent transformation of 5-HMF into LA.

Potential of a deep eutectic solvent in silver nanoparticle fabrication for antibiotic residue detection.

Deep eutectic solvents (DESs) have recently emerged as an alternative solvent for nanoparticle synthesis. There have been numerous advancements in the fabrication of silver nanoparticles (Ag NPs), but the potential of DESs in Ag NP synthesis was neither considered nor studied carefully. In this study, we present a novel strategy to fabricate Ag NPs in a DES (Ag NPs-DES). The DES composed of ᴅ-glucose, urea, and glycerol does not contain any anions to precipitate with Ag+ cations. Our Ag NPs-DES sample is used in a surface-enhanced Raman scattering (SERS) sensor. The two analytes for SERS quantitation are nitrofurantoin (NFT) and sulfadiazine (SDZ) whose residues can be traced down to 10-8 M. The highest enhancement factors (EFs) are competitive at 6.29 × 107 and 1.69 × 107 for NFT and SDZ, respectively. Besides, the linearity coefficients are extremely close to 1 in the range of 10-8 to 10-3 M of concentration, and the SERS substrate shows remarkable uniformity along with great selectivity. This powerful SERS performance indicates that DESs have tremendous potential in the synthesis of nanomaterials for biosensor substrate construction.

Macroscopic Superlattice Membranes Self-Assembled from Gold Nanobipyramids with Precisely Tunable Tip Arrangements for SERS.

A persistent challenge in utilizing Au nanocrystals for surface-enhanced Raman spectroscopy (SERS) lies in achieving controllable superstructures that maximize SERS performance. Here, a novel strategy is proposed to enhance the SERS performance by precisely adjusting the tip arrangements of Au nanobipyramids (BPs) in two-dimensional (2D) superlattices (SLs). This is achieved through ligand-exchange of Au BPs, followed by liquid-air interfacial assembly, resulting in large-area, transferrable SL membranes. The key to controlling the arrangement of Au BPs in the SLs is the regulation of the amount of free ligands added during self-assembly, which allows for the precise formation of various configurations such as tilted SLs, tip-on-tip SLs, and tip-to-tip SLs. Among these configurations, tip-on-tip SLs exhibit the highest enhancement factor for SERS, reaching an impressive value of 1.95×108, with uniform and consistent SERS signals across a large area. The experimental findings are further corroborated by simulations using the finite element method. This study establishes an efficient method for engineering the microstructure of 2D SLs composed of Au BPs, highlighting the importance of fine-tuning the tip arrangements of Au BPs to regulate SERS performance.

Macroscopic Superlattice Membranes Self‐Assembled from Gold Nanobipyramids with Precisely Tunable Tip Arrangements for SERS

AbstractA persistent challenge in utilizing Au nanocrystals for surface‐enhanced Raman spectroscopy (SERS) lies in achieving controllable superstructures that maximize SERS performance. Here, a novel strategy is proposed to enhance the SERS performance by precisely adjusting the tip arrangements of Au nanobipyramids (BPs) in two‐dimensional (2D) superlattices (SLs). This is achieved through ligand‐exchange of Au BPs, followed by liquid‐air interfacial assembly, resulting in large‐area, transferrable SL membranes. The key to controlling the arrangement of Au BPs in the SLs is the regulation of the amount of free ligands added during self‐assembly, which allows for the precise formation of various configurations such as tilted SLs, tip‐on‐tip SLs, and tip‐to‐tip SLs. Among these configurations, tip‐on‐tip SLs exhibit the highest enhancement factor for SERS, reaching an impressive value of 1.95×108, with uniform and consistent SERS signals across a large area. The experimental findings are further corroborated by simulations using the finite element method. This study establishes an efficient method for engineering the microstructure of 2D SLs composed of Au BPs, highlighting the importance of fine‐tuning the tip arrangements of Au BPs to regulate SERS performance.

Dual-functional nano-photosensitizers: Eosin-Y decorated gold nanorods for plasmon-enhanced fluorescence and singlet oxygen generation.

Photosensitizer (PS) with enhanced fluorescence is attractive for image-guided photodynamic therapy (PDT) due to its dual functional role in Singlet Oxygen Generation (SOG) and producing high fluorescence signals. Here, Eosin-Y (Ey) decorated polymer coated gold nanorods (GNRs) of different aspect ratios are synthesized and introduced as novel plasmon-enhanced nano-photosensitizers for this purpose. We show, upon excitation at 519 nm, simultaneous enhancement in fluorescence and SOG was achieved for the hybrid nanostructure. The best enhancement factors of 110 and 18 for metal-enhanced fluorescence and metal-enhanced SOG, respectively, are obtained with GNRs of length 133 nm and width 45 nm, where Ey is positioned at 12.6 nm from the metal core using layer-by-layer assembly of oppositely charged polymers. The observed plasmonic effect is critically analysed by comparing the near field damping rate along with decay length, far field scattering and nonradiative energy transfer of the nanohybrids.

Cation Chain Length of Nonhalogenated Ionic Liquids Matters in Enhancing SERS of Cytochrome c on Zr-Al-Co-O Nanotube Arrays.

Surface-enhanced Raman scattering (SERS) is a remarkably powerful analytical technique enabling trace-level detection of biological molecules. The interaction of a probe molecule with the SERS substrate shows important distinctions in the SERS spectra, providing inherent fingerprint information on the probe molecule. Herein, nonhalogenated phosphonium-based ionic liquids (ILs) containing cations with varying chain lengths were used as trace additives to amplify the interaction between the cytochrome c (Cyt c) and Zr-Al-Co-O (ZACO) nanotube arrays, strengthening the SERS signals. An increased enhancement factor (EF) by 2.5-41.2 times compared with the system without ILs was achieved. The improvement of the SERS sensitivity with the introduction of these ILs is strongly dependent on the cation chain length, in which the increasing magnitude of EF is more pronounced in the system with a longer alkyl chain length on the cation. Comparing the interaction forces measured by Cyt c-grafted atomic force microscopy (AFM) probes on ZACO substrates with those predicted by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the van der Waals forces became increasingly dominant as the chain length of the cations increased, associated with stronger Cyt c-ZACO XDLVO interaction forces. The major contributing component, van der Waals force, stems from the longer cation chains of the IL, which act as a bridge to connect Cyt c and the ZACO substrate, promoting the anchoring of the Cyt c molecules onto the substrate, thereby benefiting SERS enhancement.

Radioprotective Effects of Thymus Vulgaris L. Essential Oil on Human Peripheral Blood Mononuclear Cells

Purpose: Generated free radicals by ionizing radiations, as powerful cytotoxic agents, can damage DNA and proteins. Thymus vulgaris L (thyme) plant is a rich source of antioxidant phenolic compounds, which makes it a preferable candidate for medical applications. Given this, we set out the present study to investigate the effectiveness of thyme essential oil on Human Peripheral Blood Mononuclear Cells (PBMCs) as a radioprotector agent against ionizing radiations.
 Materials and Methods: We extracted the thyme essential oil by the conventional Clevenger extraction method. Heparinized peripheral blood samples were also collected from five male volunteers, aged 22-25, without a history of smoking and irradiation. PBMCs were isolated and the maximum nontoxic concentrations (85µg/ml (of thyme essential oil were determined based on the result of the MTT method. In the next step, the PBMCs were cultured in the presence of thyme essential oil before and after X-irradiation with doses of 0.25 and 2.00 Gy.
 Results: The most radioprotective effect was observed in the dose of 2.00 Gy for thyme-treated cells 24 hours before the irradiation (p-value ≤ 0.001) by a survival enhancement factor of 1.67, compared to the control group.
 Conclusion: Our results showed that thyme essential oil can be used as an effective radioprotector agent for PBMCs against ionizing radiations. The most radioprotective effect was observed in the presence of thyme essential oil during irradiation.

Two-dimensional tellurium nanosheet: A novel sensitive and stable surface-enhanced Raman scattering substrate

Two-dimensional (2D) materials with merits such as low cost, high chemical inertness and tunable electronic structure have become favorable candidates for next generation of surface-enhanced Raman scattering (SERS) platforms. However, the SERS sensitivity of 2D materials still needs to be improved and the large-scale synthesis methods should be developed to meet the requirements of practical applications. In this work, we explored performances of a brand-new SERS substrate made of 2D Te nanosheets (NSs), which exhibited thickness-dependent SERS properties, with thinner nanosheets yielding stronger SERS intensity. Under optimized conditions, the limits of detection (LODs) reached the order of 10−9 M combining with SERS enhancement factors (EFs) as high as 105 for copper phthalocyanine (CuPc) and methylene blue (MB). This impressive SERS performance could be attributed to the strong interaction and photoinduced charge transfer (PICT) processes between 2D Te NSs and molecules. Benefiting from the appropriate positions of valence band (VB) and conduction band (CB), the 2D Te NSs showed significant Raman enhancement for various molecules. Furthermore, the 2D Te NSs exhibited good air-stability for up to ∼2 months. These outstanding performances establish 2D Te NSs as a favorable SERS detection material with enormous potential in practical applications.

In silico identification and in vitro validation of alpha-hederin as a potent inhibitor of Wnt/β-catenin signaling pathway in breast cancer stem cells.

Cancer stem cells (CSCs) play a vital role in metastasis, recurrence and chemoresistance in breast cancer. β-catenin, which is a frequently over activated protein in CSCs, binds to T-cell factor/lymphoid enhancer factor (Tcf/Lef) family transcription factors leading to ectopic expression of Wnt pathway responsive genes necessary for the maintenance and action of CSCs. With the aim of identifying a small molecules that can effectively eliminate CSCs, molecular docking studies were performed against the Tcf/Lef binding hotspot on β-catenin using a library of 100 natural or synthetic small molecules. Small molecule ligands giving docking energy better than -7kcal/mol were further investigated by binding interactions analysis and molecular dynamics (MD) simulations. These compounds were then investigated in vitro, for cytotoxicity against CSCs isolated from MDA-MB-231 triple negative breast cancer cells. Alpha-hederin (AH) was identified as the only compound in the selected library that has cytotoxicity against breast CSCs. AH was further investigated for it's ability to regulate Wnt pathway target genes (Cyclin D1 and CD44)and the tumor suppressor p53by real-time quantitative PCR. Absorption, distribution, metabolism, excretion and toxicity properties of the AH was predicted in silico. AH significantly down regulated the transcription of Cyclin D1 and CD44 while up-regulating the transcription of p53. AH was predicted to have acceptable drug likeness. Although AH is currently known to inhibit the growth of various cancer cells in vitro, present study demonstrated for the first time that it is a potent inhibitor of Wnt/β-catenin signaling pathway and induce apoptosis in breast CSCs.