Small For Age Research Articles

The unexpected flavone synthase-like activity of polyphenol oxidase in tomato

The biosynthesis of flavones has drawn considerable attention. However, the presence of flavones and their biosynthesis in tomato (Solanum lycopersicum) remain unclear. Here, we confirmed that flavones are present in MicroTom tomato and unexpectedly found that a tomato polyphenol oxidase (SlPPO F) possesses a flavone synthase-like activity and catalyzes the conversion of eriodictyol to luteolin without the need for any cofactor. SlPPO F showed a similar Km value to that of other polyphenol oxidases, and could be inhibited by ascorbic acid. The flavone synthase-like activity of SlPPO F exhibited strict substrate specificity and only accepted flavanones with two hydroxyl groups (3′ and 4′) on the B ring as substrates. SlPPO F showed higher catalytic efficiency and better thermostability than type I flavone synthase from Apium graveolens, suggesting its possible application in enzyme engineering. In summary, we identified flavones in tomato and unraveled a polyphenol oxidase exhibiting flavone synthase-like activity.

Visible Light Photocatalytic Activity of Ag/WO3 Nanoparticles and its Antibacterial Activity Under Ambient Light and in The Dark

Nanomaterial such as metals and metal oxide photocatalysts have emerged as important tools for removing contaminants from wastewater and as antibacterial agents to prevent infections; this is mainly due to their stability under different irradiation conditions. Herein, the catalytic and antimicrobial activities of nanocrystalline silver (Ag), supported on tungsten oxide (WO3) nanoparticles prepared using the deposition-precipitation synthesis technique, are studied. The synthesized material was characterized as XRD, XPS, TEM, and TEM-EDS to investigate their physio-chemical properties. HRTEM, XPS analysis shows that the photocatalyst has a large sheet-like morphology with well-dispersed small metallic Ag particles (<3 nm) on the WO3 nanoparticle's surface, with most particles near the edges. Ultraviolet–visible spectra analysis observed a large redshift in the absorbing band edge and decreased bandgap energy from 2.6 to 2.1 eV. Photocatalytic analysis at different concentrations of 1% Ag/WO3 under visible light indicated a high degradation efficiency. The largest degradation efficiency of Methylene Blue (MB) under visible light irradiation was (∼80%) in 120 min at 1 g/L catalyst dosage. The photodegradation of MB under visible light as a function of catalyst dose followed the pseudo-first-order kinetics. In addition, the catalyst shows high degradation efficiency and significant dose-dependent inhibition of Gram-negative E. Coli and the Gram-positive S. aureus. Furthermore, the catalyst showed excellent stability and recyclability.

Consumer Acceptability and Sensory Profile of Three New Celery (Apium graveolens) Hybrids and Their Parental Genotypes

Celery is a stalky green vegetable that is grown and consumed globally and used in many cuisines for its distinctive taste and flavour. Previous investigations identified the aroma composition of celery and profiled its sensory characteristics using a trained panel; however, evaluation of the sensory characteristics of celery combined with a consumer panel, where consumer preferences and acceptability are determined, is novel. In this study, three parental genotypes (12, 22 and 25) and three new hybrids (12x22, 22x12 and 25x12) were presented to a trained sensory panel (n = 12) for profiling and a consumer panel (n = 118), where liking and preference were assessed. Celery samples were analysed by SPME GC–MS and significant differences in aroma composition between all samples were identified, causing significant differences in the sensory profile. Furthermore, significant differences in attributes assessed for liking (appearance, aroma, texture and overall) were identified. Consumer segmentation identified three groups of consumers exhibiting differences in the hedonic reaction to the samples. Sweet and bitter taste along with overall flavour were identified as drivers of liking. Hybrid 25x12 was found to be the hybrid that exhibited high intensities for most of the attributes assessed.

Arsenic content and phenolic compounds in parsley (Petroselinum crispum (Mill.) Fuss) and celery (Apium graveolens L.) cultivated in Vojvodina region, Serbia

Randomly collected samples of parsley and celery from different localities were analyzed to determine their quality based on arsenic concentrations, phenolic constituents and the antioxidant capacity of their edible parts. Arsenic concentrations were found in the range: parsley root (0.16 μg/g d.m.) &lt; celery root (0.19 μg/g d.m.) &lt; parsley leaf (0.35 μg/g d.m.) &lt; celery leaf (0.45 μg/g d.m.). Total phenolic contents in roots were similar in both species and varied significantly depending on the cultivation site: 5.03-9.18 mg eqGA/g DE in parsley and 5.04-8.50 mg eqGA/g DE in celery. Lower total flavonoids content was recorded in celery. Among the phenolic acids, ferulic, chlorogenic and several cinnamic acids dominated. Apigenin and its glucosides dominated among flavonoids. Based on the principal component analysis (PCA) it can be concluded that the As content varied depending on the geographical origin of the samples. Also, phenolic compounds showed a significant contribution on PCA clustirng, indicating that cultivation site has a clear significant impact on the metabolites profile, while As content in plants did not significantly affect phenolic compound profile.

Determination of Chemical Composition, In Vitro and In Silico Evaluation of Essential Oil from Leaves of Apium graveolens Grown in Saudi Arabia.

The aim of this study was to explore the composition and evaluate the in silico and in vitro antioxidants and antimicrobial and anti-inflammatory effects of Apium graveolens var. dulce leaves essential oil (AGO) collected from Al-Kharj (Saudi Arabia). AGO was isolated using the hydro-distillation method, and its composition was studied using gas-chromatography-mass Spectrometry (GC–MS), antimicrobial activities using well diffusion assay, and antioxidant and anti-inflammatory activities using spectrophotometric methods. The pharmacological activities of their major compounds were predicted using PASS (prediction of activity spectra for substances) and drug-likening properties by ADME (absorption, distribution, metabolism, and excretion) through web-based online tools. Isocnidilide (40.1%) was identified as the major constituent of AGO along with β-Selinene, Senkyunolide A, Phytyl acetate, and 3-Butylphthalide. AGO exhibited a superior antibacterial activity, and the strongest activity was detected against Gram-positive bacteria and Candida albicans. Additionally, it exhibited a weaker antioxidant potential and stronger anti-inflammatory effects. PASS prediction supported the pharmacological finding, whereas ADMET revealed the safety of AGO. The molecular docking of isocnidilide was carried out for antibacterial (DNA gyrase), antioxidant (tyrosinase), and anti-inflammatory (cyclooxygenase-2) activities. The docking simulation results were involved hydrophilic interactions and demonstrated high binding affinity of isocnidilide for anti-inflammatory protein (cycloxygenase-2). The presence of isocnidilide makes AGO a potential anti-inflammatory and antimicrobial agent. AGO, and its major metabolite isocnidilide, may be a suitable candidate for the future drug development.

Influence of Ag Clusters on the Electronic Structures of β-Ga2O3 Photocatalyst Surfaces.

In order to understand the photocatalytic carbon dioxide reduction over Ag-loaded β-Ga2O3 photocatalysts, first principles calculations based on density functional theory were performed on the surface model of a Ag cluster-adsorbed β-Ga2O3 system. The stable adsorption structures of Agn (n = 1 to 4) clusters on the β-Ga2O3 (100) surface were determined. In the electronic structure analysis, the valence states of all Ag clusters mixed with the top of the O 2p valence band of Ga2O3, leading the Fermi level of Agn/β-Ga2O3 to shift to the bottom of the conduction band. It was also revealed that the unoccupied states of Agn clusters overlapped with the Ga unoccupied states, and occupied electronic states of Ag clusters were formed in the band gap. These calculation results corresponded to the experimental ones obtained in our previous study, i.e., small Ag clusters had strong interaction with the Ga2O3 surface, enhancing the electron transfer between the Ag clusters and the Ga2O3 surface. That is, excited electrons toward Agn clusters or the perimeter of Ag-Ga2O3 should be the important key to promote photocatalytic CO2 reduction.

Detection of celery (Apium graveolens) allergen in foods of animal and plant origin by droplet digital PCR assay

Celery is included among the allergenic foods that, under the EU 1169/2011 regulation, must be declared in the ingredient list. However, disposition covers only allergens that are voluntary used as ingredients and not the accidental presence of allergens in a food as consequence of cross contamination. To guarantee compliance with food allergen regulations and protect health of food-allergic consumers are needed specific and sensitive methods to detect the presence of allergens in foods. Detection of allergens relies of protein- and DNA-based methods. Real-time PCR (RT-PCR) targeting sequences from the mannitol dehydrogenase (Mtd) gene is currently the method of choice for detection and quantification of celery in foods. However, quantification by RT-PCR methods needs standard calibration curves of the target DNA. To overcome this limitation in the present study the use of a droplet digital PCR (dd-PCR) assay has been proposed for the quantification of celery in foods. A preliminarily optimization of the dd-PCR protocol was conducted using serial DNA dilution extracted from celery powder. Ideal primer probe concentrations were 0.9 μM of both forward and reverse primers and 0.250 μM of probe. The optimal annealing temperature was at 60 °C. The limit of detection (LOD) was 0.20 ± 0.12 Cp/μL while the limit of quantification (LOQ) was 0.83 ± 0.20 Cp/μL. The dd-PCR assay showed no cross-reactivity with other vegetal species, indicating a good specificity. No effect of food matrix was observed on the dd-PCR performance. The method was able to quantify the presence of celery in commercial foods of animal and plant origin.

Mesoporous silica nanosheets with well-dispersed small Ag nanoparticles for the construction of robust transparent antibacterial nanocoatings

The fabrication of robust transparent antibacterial nanocoatings on the surface of device and equipment has significant implication for protecting human from bacterial infections in daily life. However, it still faces some challenges such as low antibacterial efficiency and poor mechanical stability, which hinder their wide applications. Therefore, it is urgent to explore the design and fabrication of superior antibacterial nanocoatings with high-robustness. In this work, robust transparent antibacterial nanocoatings were successfully fabricated by employing two-dimensional mesoporous nanosheets as a novel building block. Aminopropyl-modified mesoporous silica nanosheets (MSNSs-NH 2 ) with uniform pore sizes of ca. 5–8 nm were first fabricated by one-pot liquid-liquid interface growth method, and were employed as a carrier to achieve well-dispersed loading of many small Ag nanoparticles (NPs) of ca. 2–4 nm to form MSNSs-NH 2 @Ag as antibacterial agent. Next, robust transparent antibacterial nanocoatings were prepared by simple dip-coating method without any post-processing. It is worth noting that the use of two-dimensional MSNSs-NH 2 with large spreading area not only facilitates the uniform loading of small Ag NPs for high antibacterial capacity of nanocoatings, but also is beneficial to enhance the mechanical robustness of nanocoatings due to the firm spreadability of single layer mesoporous nanosheets on the flat substrates. The optimal coated glass slide exhibits the enhanced transmittance (94.2% at 535 nm), high-mechanical robustness (pencil hardness test: ≥3H, tape adhesion test: ≥4B) and excellent antibacterial activity (at least killing 80% bacteria) toward Gram-negative Escherichia coli . This work may provide an exploration strategy to construct multifunctional nanocoatings by using the novel mesoporous nanosheets as a building block. Robust transparent antibacterial nanocoatings were fabricated by employing Ag nanoparticles-loaded mesoporous silica nanosheets as building block. • The two-dimensional aminopropyl-modified mesoporous silica nanosheets (MSNSs-NH2) was chosen as a novel building block. • Many small Ag nanoparticles (NPs) are uniformly loaded on the MSNSs-NH2. • The single layer spreadability of nanosheet not only decreases its usage amount, but also enhances mechanical robustness. • The robust transparent antibacterial nanocoatings were prepared by simple dip-coating method without any post-processing.

Efficacious CO2 Adsorption and Activation on Ag Nanoparticles/CuO Mesoporous Nanosheets Heterostructure for CO2 Electroreduction to CO.

It is an ongoing pursuit for researchers to precisely control the catalyst's surface for high-performance CO2 electrochemical reduction (CO2ER). In this work, CuO mesoporous nanosheets (CuO MNSs) with rough edges decorated by small Ag nanoparticles (Ag NPs) with a tunable amount of Ag were synthesized on a Cu foil at normal atmospheric temperature through two-step solution-phase reactions for CO2ER to CO. In this special Ag NPs/CuO MNSs heterostructure, the mesoporous CuO NSs with rough edges favored gas infiltration, while decorated Ag NPs expanded the active sites for CO2 molecule adsorption. Ag NPs endowed Ag NPs/CuO MNSs with good electrical conductivity and promoted the adsorbed CO2 molecules to obtain electrons from the catalyst. Especially, the Ag-CuO interface stabilized the *COOH intermediate with strong bonding, which is important in boosting CO2ER to CO. The optimal Ag1.01%/CuO can catalyze CO2ER to CO with a Faradaic efficiency of 91.2% and a partial current density of 10.5 mA cm-2 at -0.7 V. Moreover, it exhibited prominent catalytic stability, retaining 97.8% of the initial current density and 97.6% of the original Faradaic efficiency for CO after 12 h of testing at -0.7 V. Notably, the Faradaic efficiency of CO on Ag1.01%/CuO can retain over 80% in the potential area from -0.6 to -0.9 V, embodying its high selectivity for CO. This work develops precious metal/metal oxide heterostructures with a low precious metal loading for efficacious CO2ER to CO and beyond.

Efektifitas Berbagai Zat Pengatur Tumbuh (ZPT) Alami Pada Pertumbuhan Tanaman Seledri (Apium graveolens L.)

The experiment was carried out in Ciumbuleuit, Hegarmanah Sub-district, Cidadap District, Bandung City, with an altitude of 875 meters above sea level with the Andosol order. The time of the experiment was started from June - August 2020. The purpose of this study was to study and analyze the effectiveness of the best natural growth regulators (ZPT) on the growth of celery (Apium graveolens L.). The experimental design used was a simple randomized block design (RBD) with four treatments and repeated six times. The treatments were A = 100% water (control), B = 30% shallot extract, C = 30% bean sprout extract, and D = 30% coconut water. The results showed that different natural ZPT administration had an effect on the growth of celery plants. And the experimental results based on independent tests showed that giving D treatment, coconut water at a concentration of 30% affected the growth of plant height 21 DAS, number of leaves 35 DAS and 42 DAS, leaf length 35 DAS and 42 DAS and the number of tillers 42 DAS on celery plants compared other treatment.

Foliar silicate application improves the tolerance of celery grown under heat stress conditions

Temperature rise is one of the most challenging climate change impacts that increase the intensity of heat stress. In this investigated the production of celery (Apium graveolens var. rapaceum F1 hybrid)) was tested during the late season. The experiment was carried out during the two successive summer seasons of 2019 and 2020 in Giza Governorate, Egypt. The experimental design is a split-plot, the main plots consist of three low tunnel cover treatments, and three spray treatments with three replicates in sub-main plots. Results showed that the use of white net cover gave the highest vegetative growth and yield followed by the black net. Values of plant yield were 951, 765, and 660 g/plant for white, black and without cover, respectively, in the first season. The foliar application of 3 mM of potassium silicate produced the highest vegetative growth and yield compared to the control treatment. Referring to the effect of spray foliar application of potassium silicate on yield 1.5 mM (S1), 3 mM (S2), and control were 892, 795, and 689 g/plant in the first season, respectively. The best combination that delivered the highest vegetative growth and yield was a cover low tunnel with a white net combined with S2 foliar application.

Investigating the Relationship of Genotype and Geographical Location on Volatile Composition and Sensory Profile of Celery (Apium graveolens).

Numerous varieties of celery are grown in multiple countries to maintain supply, demand and availability for all seasons; thus, there is an expectation for a consistent product in terms of taste, flavour, and overall quality. Differences in climate, agronomy and soil composition will all contribute to inconsistencies. This study investigated the volatile and sensory profile of eight celery genotypes grown in the UK (2018) and Spain (2019). Headspace analysis determined the volatile composition of eight genotypes, followed by assessment of the sensory profile using a trained panel. Significant differences in the volatile composition and sensory profile were observed; genotype and geographical location both exerted influences. Two genotypes exhibited similar aroma composition and sensory profile in both locations, making them good candidates to drive breeding programmes aimed at producing varieties that consistently display these distinctive sensory properties. Celery samples harvested in the UK exhibited a higher proportion of sesquiterpenes and phthalides, whereas samples harvested in Spain expressed a higher aldehyde and ketone content. Studying the relationship between growing environment and genotype will provide information to guide growers in how to consistently produce a high-quality crop.

Giving Boiled Celery Leaves to Reduce Blood Pressure in Elderly People with Hypertension

The high incidence of hypertension in the elderly and uncontrolled triggers degenerative diseases such as congestive heart failure, kidney failure, and vascular disease such as stroke and peripheral arterial disease. The high incidence of hypertension is directly proportional to the high complications that occur, so adequate nonpharmacologic treatment is needed. Celery (Apium graveolens L.) is one of the types of herbal therapy used to treat hypertension. Traditional Chinese society has long used celery to lower blood pressure. The purpose of this study was to determine the effect of celery leaf decoction on elderly blood pressure in patients with hypertension in the Mambi Health Center, Mamasa District. His research method is a quasi-experimental method, using a time-series research design. This study took a sample of 20 people. The sampling techniques were consecutive sampling, and the measuring instruments used were observation sheets and spigmanometers. Analyzed by the Friedman test with a significance level of alpha = 0.05. The results of the study obtained statistical tests showing that there were significant differences by comparing systolic blood pressure before, 3 days of administration and 7 days of administration of celery leaves, obtaining a mean value which decreased from the first day, the third day and the days of 2.75, 2.23 and 1.03 with a value of 0.000 &lt;0.05, as well as Diastolic blood pressure, respectively, 2.75, 1.98 and 1.30 with p value of 0.000 &lt;0.05, which means there is an effect of giving celery leaf decoction to reduce systolic and diastolic blood pressure

Optimization of Volatile Compounds Extraction from Industrial Celery (Apium graveolens) By-Products by Using Response Surface Methodology and Study of Their Potential as Antioxidant Sources.

In this study, the potential of industrial celery by-products (the stalk and root) serving as sources of aromatics and antioxidants was investigated. A headspace solid phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) procedure was optimized to isolate volatile compounds from celery by-products. A Box–Behnken experimental design was proposed to optimize the procedure through a response surface methodology. The optimal extraction conditions were found to be 1.6 g of homogenized fresh by-product at 30 °C for 60 min. Under these conditions, 26 volatile compounds in stalk and root samples were identified, monoterpenes and sesquiterpenes being the main components. The content of limonene and γ-terpinene found in the stalk was significantly higher in comparison with root samples. Total phenolic content and antioxidant activity (ABTS and FRAP) results underlined the celery wastes studied as good sources of free radical scavengers. This work suggests the potential application of these by-products in the food industry and opens new pathways to valorize celery residues, contributing to the circular economy.

Evaluation of Apium graveolens from different geographical origins based on TLC-fingerprint and chemometrics

Apium graveolens (celery) has various roles both in the food and medicine sectors. It grows very well in the tropical and subtropical areas of Africa and Asia, including Indonesia. This Apiaceae member contains a number of phytoconstituents, and geographical origin is known to significantly determine the type and concentration of phytochemicals in plant material. This study was carried out to validate and develop thin layer chromatography (TLC)-based fingerprinting combined with chemometrics, i.e., Principal Component Analysis (PCA) and Cluster Analysis (CA), to evaluate the quality of celery harvested from thirteen different geographical origins in Indonesia. The mobile phase was first optimized with a simplex axial design, resulting in 2-propanol, toluene, and dichloromethane (1:6:1) as the optimum mobile phase for a stable and precise TLC system in the celery sample analysis. When analyzed with chemometrics, the TLC-fingerprints could discriminate celeries from various origins. The PCA score plot of the first two principal components (PCs) and CA clearly distinguished the samples’ properties and classified them into four clusters. Samples grouped into one cluster were concluded to have comparable quality, while those in different clusters had different qualities.

Dl-3-N-Butylphthalide Presents Anti-Cancer Activity in Lung Cancer by Targeting PD-1/PD-L1 Signaling.

IntroductionLung cancer serves as one of the most malignant cancer types. Immunotherapy targeting PD-1/PD-L1 axis is a promising strategy for cancer treatment. Dl-3-N-butylphthalide (NBP), a small molecule compound extracted from the seeds of Apium graveolens, possesses a large range of biological effects and demonstrates anti-cancer activities. However, the role of NBP in the modulation of lung cancer remains obscure.MethodsIn this study, we aimed to explore the effect of NBP on PD-L1 signaling and the progression of lung cancer.ResultsSignificantly, the treatment of NBP repressed the proliferation of lung cancer cells in vitro. Tumorigenicity analysis in nude mice showed that the tumor volume and tumor weight were attenuated by the treatment of NBP in the mice. Meanwhile, the levels of Ki-67 and PD-L1 were reduced by the treatment of NBP in the tumor tissues of the mice. NBP suppressed IFN-γ-induced PD-L1 enhancement in lung cancer cells. The treatment of NBP inhibited PD-L1 expression in lung cancer cells co-cultured with unstimulated PBMCs or activated T cell. NBP inhibited PD-1 expression in activated T cells co-cultured with lung cancer cells. Conditioned medium from activated T cells increased PD-L1 expression, and NBP reversed this effect. Co-culture with A549 and H1975 cells reduced T cell proliferation and activity, while the treatment of NBP reversed the reduction. Consistently, the treatment of NBP caused notably decreased apoptosis of co-cultured T cells. Mechanically, KAT7 was able to bind to PD-L1 promoter and epigenetically induce PD-L1 expression by promoting the enrichment of histone H3 lysine 14 acetylation (H3K14ac) and RNA polymerase II on PD-L1 promoter.DiscussionThus, we concluded that NBP repressed PD-L1 expression by targeting KAT7 and attenuated PD-1/PD-L1 axis to relieve lung cancer progression. NBP may be applied as the potential therapeutic strategy in immunotherapy of lung cancer.

Enhanced and sustainable control of Myzus persicae by repellent plants in organic pepper and eggplant greenhouses.

Repellent plants (RPs), generally used to keep pests away from crops in integrated pest management, have been shown to reduce the need for synthetic insecticide sprays in various agroecosystems. However, few studies have evaluated the pest control efficiency of RPs over the entire growth period of crops. To evaluate the effect of RPs against Myzus persicae and explore the application and management modes of RPs in the field, we planted mint (Mentha haplocalyx), mung bean (Vigna radiata), celery (Apium graveolens) and coriander (Coriandrum sativum) near the ventilation openings of commercial greenhouses. Five-month sampling results showed that mung bean and mint treatments significantly reduced M. persicae population levels over the entire growth period, whereas celery and coriander reduced aphid infestations during the main harvest period of eggplant. The four RP species showed the strongest repellence during their fast-growth periods. Mung bean and mint shortened the activity period of M. persicae in pepper by delaying the pest in reaching its peak activity. Celery and coriander reduced aphid density on eggplant during their main activity period. Mint, celery and coriander inhibited population growth in M. persicae in the laboratory, revealing the potential value of RPs in reducing M. persicae population levels in the field. Mint, mung bean, celery and coriander planted near ventilation openings could be used to control M. persicae infestations in commercial greenhouses. Early planting and timely replanting of RPs is a more effective, environmentally friendly and suitable method for organic pest control compared with chemical pesticides. © 2021 Society of Chemical Industry.

Three-dimensional surface-enhanced Raman scattering substrates constructed by integrating template-assisted electrodeposition and post-growth of silver nanoparticles

Three-dimensional (3D) plasmonic nano-arrays can provide high surface-enhanced Raman scattering (SERS) sensitivity, good spectral uniformity and excellent reproducibility. However, it is still a challenge to develop a simple and efficient method for fabrication of 3D plasmonic nano-arrays with high SERS performance. Here we report a facile approach to construct ordered arrays of silver (Ag) nanoparticles-assembled spherical micro-cavities using polystyrene (PS) sphere template-assisted electrodeposition and post-growth. The electrodeposited small Ag nanoparticles grow into bigger stable nanoparticles during the post-growth process, which could significantly improve the SERS sensitivity. The Ag nanoparticles-assembled 3D micro-cavity array provides much more hotspots in the excitation laser beam-covered volume than the two-dimensional counterpart. The relative standard deviation (RSD) of 612 cm−1 peak of rhodamine 6G (R6G) was calculated to be 8%, and the RSD of the characteristic peak taken from substrates of different batches was less than 10%. The detectable lower concentration as low as 1 fM was achieved for an aqueous solution of R6G. Such SERS substrate also showed high sensitivity to thiram (fungicide) and paraquat (herbicide) in water with limits of detection of 0.067 nM and 2.5 nM respectively. Furthermore, it also demonstrated that SERS detection of pesticide residues on fruits can be realized, showing a potential application in rapid monitoring food safety.

Significantly improved photo carrier injection by the MoS2/ZnO/HNP hybrid UV photodetector architecture

A unique ultraviolet (UV) photodetector architecture of MoS2/ZnO/HNP is explored and significantly increased photocurrent (Iph) of 4 × 10−3 A is demonstrated under the 385 nm illumination of 54.9 mW/mm2 at 10 V. This leads to the superior device performance factors: i.e., photoresponsivity of 21,111 mA/W, detectivity of 7.9 × 1011 jones and EQE of 6,800 %. These device performance factors confirm that the proposed photodetector configuration is superior as compared to the similar versions of ZnO-based UV photodetectors. The hybrid MoS2/ZnO/HNP architecture is constructed by the 2-D transition metal dichalcogenide MoS2 nanoflakes, wide-bandgapZnO quantum dots (QDs) and plasomonic PdAg hybrid nanoparticles (HNPs). The increased Iph is related to the hot carrier injection through the strongly improved localized surface plasmon resonance (LSPR) by the PdAg HNPs and additional photo carriers from the 2-D MoS2 nanoflakes on top of the original photo-induced carriers in the ZnO QD layer. The PdAg HNPs are fabricated by a unique two-step solid-state dewetting (SSD) technique, having the core-shelled PdAg NPs with the high-density small background Ag NPs. This HNP configuration offers very high-density hot spots and significantly improved LSPR. The photocurrent enhancement of MoS2/ZnO/HNP architecture is systematically studied by the finite-difference time-domain (FDTD) simulations.

Enhancement of SERS effect in Graphene-Silver hybrids

Surface enhanced Raman spectroscopy (SERS) is considered as one of the most intensively studied analytical technique. Here, Ag nanoparticles (NPs) are coated on graphene layers (GLs) to prepare a hybrid SERS substrate. GLs are known to contribute towards SERS based on chemical enhancement mechanism, and Ag NPs are based on electromagnetic enhancement mechanism. Thus, the synergetic effect of hybrid could be utilized to prepare excellent SERS substrates. Furthermore, effect of Ag NPs with varying size has been studied to check the improvement in SERS. Ten times remarkable enhancement in SERS intensities are observed from the GLs-Ag hybrid as compared to pristine GLs. Density functional theory (DFT) calculations have been carried out through small Ag clusters interaction with graphene fragments to support and understand the mechanism behind the observed phenomena. Strong adsorption of Ag3 cluster on graphene fragment reveals the substantial modification in electronic and vibrational properties of graphene fragment and considerable charge transfer from Ag3 cluster to graphene fragment. Such phenomena further result in G-band’s enhanced intensity in graphene fragment. Our experimental study and theoretical calculations set up basic understanding and open up a way to fabricate the high-performance SERS substrates for proficient sensing applications.