Decoration Of Silver Nanoparticles Research Articles

Study on the enhanced performance of visible photodetector based on hybrid structure between reduced graphene oxide and modified ZnO nanorods

Photodetectors based on Zinc oxide (ZnO) have been widely researched due to their significant advantages such as simple fabrication process, high stability, etc. However, the application range of these devices is still limited in the ultraviolet (UV) region, and their reported performance is not as high as desired. Therefore, this study introduces a simple fabrication process of a photodetector based on the hybrid structure of reduced graphene oxides and zinc oxide nanorods (ZnO NRs) decorated silver nanoparticles (Ag NPs). In this RGO/ZnO–Ag structure, the ZnO–Ag serves as a light absorption complex to generate charge carriers through the surface plasmon resonance (SPR) effect and RGO acts as a transport layer driving the photocarriers for the enhancement of photocurrent. The results show that by decorating Ag NPs onto ZnO NRs, the absorption range of ZnO was widened toward longer wavelengths (the optical band gap reduced from 3.2 eV to 3.12 eV). Besides, by incorporating an RGO transport layer, not only the response and recovery time of the ZnO–Ag device were shortened but also its performance parameters were significantly enhanced (the responsivity increased from 5.32 to 6.58 A W−1 and the photoconductive gain rose from 16.92 to 20.70). This reveals the promise of our innovation in hybrid structure of transport layer and modified ZnO for practical photodetector applications.

A new highly sensitive flexible SERS substrate: CVD graphene/copper foil decorated by Ag NPs

Graphene-mediated surface-enhanced Raman scattering (SERS) substrates are currently being investigated for their potential in ultrasensitive detection. Graphene (G) combined with plasmonic metal nanostructures is expected to provide an exceptional SERS response. Here, we prepared a flexible multilayer composite structure by directly decorating silver nanoparticles (Ag NPs) on CVD graphene/copper foil under ultrasonic conditions. Due to the multi-dimensional plasmonic coupling of precious metals, extra chemical enhancement and exceptional molecule harvesting capability of G interlayer, the as-prepared Ag/G/Cu multilayer composite structure manifested ultrahigh sensitivity with the detection limit of Rhodamine 6G (R6G) as low as 1.0 × 10-14 M and a high enhancement factor (EF) of 8.86 × 108. The high performance flexible SERS substrate, with its ingenious process and simple structure, demonstrates excellent potential for applications in environmental protection.

Decoration of silver nanoparticles over chitosan-Arabic gum hydrogel: Synthesis, characterization and investigation of its antioxidant and anti-colorectal cancer activities

The present study describes the production of hybrid biopolymer hydrogel supported Ag NPs in a sustainable manner, along with its biological investigations and characterizations. A composite hydrogel of chitosan and Arabic gum (CS-AG) was utilized as the support or template for the green synthesis of nanoparticles. By taking advantage of their electron-rich organo-functions, the biopolymers could function as both an encapsulating stabilizer of the Ag NPs and a green-metric reductant of the incoming Ag ions. The physicochemical properties of the material were evaluated using an array of advanced analytical techniques like X-ray diffraction (XRD), elemental mapping, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier Transformed Infrared Spectroscopy (FT-IR), UV–Vis spectroscopy and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Towards the biological implication, the material was used in anticancer studies against HT-29 and Caco-2 colon cancer cell lines using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)colorimetric method, as well as in the biological evaluation of antioxidant properties by the DPPH (2,2-diphenyl-1-picrylhydrazyl)method. The substance appeared to have strong anticancer properties based on the DPPH assay's noteworthy IC50 value. Remarkably, it was discovered that the percentage of malignant cell lines' cell viability decreased over the Ag NPs@CS-AG nanocomposite in a dose-dependent manner. The MTT assay produced the corresponding IC50 values against the two cell lines, which were 366.1 μg/mL and 264.5 μg/mL, respectively. At 545 nm, the absorbance rate was assessed, showing toxicity on normal cell line (CHO) up to 1927 μg/mL, which was quite insignificant.

NiAl LDH nanosheets based on Ag nanoparticles-decoration and alkali etching strategies for high performance supercapacitors

Layered double hydroxides (LDHs) represent a category of two-dimensional layered intercalation materials, showing significant potential as electrode materials for the production of high-energy-density supercapacitors due to their tunable composition, ease of synthetic modification, and low cost. Here, we constructed alkali-etched NiAl LDH-OH nanosheets/Ag nanoparticles (NPs) composite material (Ag@NiAl LDH-OH) for high-performance supercapacitors through a simple solvent-thermal reaction. The alkali treatment is employed to selectively etch some Al3+ ions, generating cation vacancies as active sites for energy storage. Additionally, under the simultaneous influence of strong alkalis and vacancies, the interlayer spacing of LDHs expands, aiding in the promotion of interlayer ion mobility. Meanwhile, the decoration of silver nanoparticles ensures excellent electron conductivity in the NiAl-LDH-OH nanosheets, thereby facilitating improved utilization of the active substance and achieving outstanding rate performance. The Ag@NiAl LDH-OH electrode, when prepared, demonstrates a significant increase in specific capacitance, reaching 1790 F g−1 at a current density of 1 A g−1. This represents approximately 7 times the specific capacitance of the pristine NiAl LDH electrode, with a capacity retention of 79 % even under a high current density of 20 A g−1. Moreover, the assembled asymmetric supercapacitor (ASC) attains a maximum energy density of 138.25 Wh kg−1 at a power density of 700 W kg−1, maintaining 81 % of its initial specific capacitance after 20000 cycles. This research introduces novel pathways for advancing high-energy-density SCs.

Surface decoration of plasmonic Ag nanospheres for enhanced visible light photocatalysis of BiVO4

The industrial concern of producing benzaldehyde (BD) more efficiently is the key aspect of this work. Therefore, the oxidation of benzyl alcohol (BA) by photocatalytic route was chosen. The amoeba-like BiVO4 (BV) particles were synthesized by co-precipitate method since it gives higher yield when compared to other methods and silver nanoparticles were decorated over its surface by photo deposition method. Due to surface plasmon resonance (SPR effect), the decorated samples showed enhanced optoelectronic properties. The band edge positions shifted to higher energy levels profitably paving the way for the production of superoxide radicals (•O2−) effectively. The optimal catalyst material was engineered in such a way that it would facilitate the production of both •O2− and BA* radicals and inhibits the production of BD* radical. The decorated silver nanoparticles aided in increasing the surface area and the number of catalytic active sites, therein a 4.7-fold increase in benzaldehyde yield was achieved when compared to pure BV. Since monoclinic BV possesses piezoelectric property, the use of ultrasound in the reaction medium boosted the efficiency of the reaction and henceforth a maximum conversion of 88.29 % was obtained. Hydrogen peroxide formed as a byproduct, adds commercial value to this reaction.

Layer-by-layer structured nanocomposite deposits from plasma-synthesized organosilicon nanoparticles and organosilicon nanoparticles decorated with Ag nanoparticles by taking advantage of cyclic nanoparticle formation in Ar/HMDSO reactive plasmas

Rational engineering of thin nanocomposite layers, deposited in reactive plasmas, requires knowledge on the plasma behavior in order to produce multifunctional deposits with tailored properties (structural, optical, electrical, etc.) This work presents an experimental study of nanoparticles synthesized in the plasma gas-phase and their subsequent use as building-blocks to form layer-by-layer nanostructures. The experiment is performed in a plasma process that successfully combines plasma polymerization of an organosilicon molecular precursor (hexamethyldisiloxane, HMDSO) and sputtering of a metallic (silver) target. Pulsed injection of the precursor is found to promote cyclic nanoparticle formation in Ar/HMDSO reactive plasmas. The plasma electron temperature is found to vary in the range 1.6—2.2 eV as derived from time-resolved optical emission spectroscopy of the plasma energetic conditions. This diagnostic method is also shown to provide a reliable tool for online monitoring of the nanoparticle synthesis process. Two types of layer-by-layer structured nanocomposites can be obtained depending on the type of nanoparticles synthesized: (i) organosilicon nanoparticles of size less than 100 nm in all studied plasma conditions for a large quantity of injected HMDSO and (ii) raspberry-like nanoparticles of size less than 150 nm when the quantity of injected HMDSO is reduced. The organosilicon nanoparticle growth follows a polydimethylsiloxane (PDMS)-like oligomerization scheme in which the R2-Si(-O)2 silicon bond tends towards the formation of polymeric structure in a R3-Si(-O)1 silicon chemical environment, containing Si-(CH2)-Si type bridges that are involved in cross-linking. The elemental composition of the raspberry-like nanoparticles is similar to that of the organosilicon nanoparticles, supplemented by the Ag component. The decorating silver nanoparticles are ∼15 nm of size, round in shape and polycrystalline. There is no evidence for silver oxides in the nanostructures. The Si-O-Ag bridges, revealed by infrared spectroscopy, suggest the presence of junction sites between the metallic and the organosilicon parts of the raspberry-like nanoparticles. The silver nanoparticles are found to decorate the organosilicon nanoparticles to form the raspberry-like nanoparticles in the plasma gas-phase, before being deposited. This reveals a very interesting phenomenon of simultaneous growth of the silver- and organosilicon-parts in the plasma without mixing during the nucleation phase.

Carbon dots-adorned silver nanoparticles as a straightforward sustainable colorimetric sensor for the rapid detection of ketotifen in eye drops and aqueous humor

The rapid and accurate detection of drug molecules in pharmaceutical formulations and biological samples is of paramount importance. In this research article, we present a novel colorimetric sensor based on carbon dots decorated silver nanoparticles (CDs/AgNPs) for the rapid detection of ketotifen (KTF), a widely used antihistamine drug. The CDs were synthesized via a facile one-step microwave-assisted method and subsequently conjugated onto AgNPs through a simple adsorption process, forming a stable CDs/AgNPs composite. The resulting composite exhibited unique optical properties, including a strong absorption peak at 410 nm with remarkable intensity reduction and color changes upon the addition of KTF. The developed colorimetric sensor exhibited a wide linear range of 3.0–40.0 µg mL−1 (R2 = 0.9996), with a %RSD of 2.41, and a low limit of detection (LOD) of 0.981 µg mL−1. Furthermore, the sensor's practical applicability was evaluated by successfully detecting KTF in eye drops and artificial aqueous humor, demonstrating a remarkable percentage recovery exceeding 96.0 %. Finally, a comprehensive evaluation of the greenness and blueness of the method was performed using analytical eco-scale, GAPI, AGREEprep, and BAGI tools. The results of these assessments indicate its exceptional sustainability. Overall, the proposed method holds significant potential for applications in pharmaceutical quality control and therapeutic monitoring, contributing to improved patient care and drug safety in the field of ophthalmology.

Edge-site selective decoration of silver nanoparticles on TiO2 nanosheets for the rapid catalytic reduction of nitroarenes

In this study, we aim to construct an edge-site selective deposition of silver nanoparticles on TiO2 nanosheets (Ag-TiO2NSs) for the catalytic reduction of toxic nitroarenes (NAs) using NaBH4 medium. The as-prepared Ag-TiO2NSs were characterized by various analytical techniques such as XRD, HR-TEM, SEM-EDAX, elemental mapping and XPS analyses. The HR-TEM images confirmed that the Ag nanoparticles (AgNPs) size of around 3.05 ± 0.5 nm in diameter exhibited the selective growth specifically on the edges of the TiO2NSs. Additionally, it was observed that the TiO2NSs exhibited a high exposure of (101) facets. The prepared Ag-TiO2NSs catalyst exhibited remarkably high catalytic activity in the reduction of 4-nitrophenol (4-NP) (∼6 min, Kapp: 9.2 × 10−3 s−1 and TOF: 1.13 × 10−6 mol mg−1 min−1), which was comparable to or surpassing the catalytic performance of most of the previously reported Ag-based catalysts. Moreover, the catalyst showed an excellent catalytic reduction ability of other NAs such as 4-nitroaniline (4-NA) (∼10 min, 2.8 × 10−3 s−1), 4-(4-nitrophenyl)morpholine (4-NM) (∼8 min, 6.0 × 10−3 s−1), and 4-(2-fluoro-4-nitrophenyl)morpholine (4-FNM) (∼11 min, 4.2 × 10−3 s−1). In addition, the Ag-TiO2NSs exhibited commendable recyclability, with a minimal decrease in the activity over four consecutive recycling operations. The exceptional catalytic performance could be attributed to the smaller size of the AgNPs along with the synergistic effect between AgNPs and their interfacial contact with the (101) facet exposure of TiO2NSs. The Ag-TiO2NSs catalyst demonstrated the potential application for the catalytic reduction of 4-NP in a fixed bed reactor, operating under mild reaction conditions.

Green Decoration of Silver Nanoparticles on Hydroxymethylated Lignin-Modified Magnetic Nanoparticles Using Cydonia oblonga Flower Extract: Evaluating of Its Catalytic, Antioxidant and Cytotoxic Effects Against 6 Thyroid Cancer Cell Lines

Green Decoration of Silver Nanoparticles on Hydroxymethylated Lignin-Modified Magnetic Nanoparticles Using Cydonia oblonga Flower Extract: Evaluating of Its Catalytic, Antioxidant and Cytotoxic Effects Against 6 Thyroid Cancer Cell Lines

One-drop chemosensing of dapoxetine hydrochloride using opto-analysis by multi-channel μPAD decorated silver nanoparticles: introducing a paper-based microfluidic portable device/sensor toward naked-eye pharmaceutical analysis by lab-on-paper technology.

Dapoxetine (DPX) belongs to the selective serotonin reuptake inhibitor (SSRI) class and functions by blocking the serotonin transporter and increasing serotonin activity, thereby delaying ejaculation. Therefore, monitoring of the concentration of DPX in human biofluids is important for clinicians. In this study, application of silver nanoparticles with the morphology of prisms (AgNPrs) for the sensitive measurement of DPX using colorimetric chemosensing and the spectrophotometric method was investigated. Also, DPX was determined in real samples using the spectrophotometry method. Based on the obtained results, all of the detection process in colorimetric assay is related to morphological reform of AgNPrs after it's specific electrostatic and covalent interaction with DPX as analyte. The UV-vis results indicate that the proposed AgNPrs-based chemosensing system has a wide range of linearity (0.01 μM to 1 mM) with a low limit of quantification of 0.01 μM in human urine samples, which is suitable for clinical analysis of this drug in human urine samples. It is important to point out that, this chemosensing strategy showed inappropriate analytical results for the detection of DPX in human urine samples which is a novelty of this platform. Finally, the optimized microfluidic paper-based analytical device (μPAD) was integrated with the colorimetric analysis of DPX to provide a time/color system for estimating analyte concentration by a portable substrate toward in situ and on-site biomedical analysis. Interestingly, the analytical validation tests showed appropriate results with great stability, which may facilitate commercialization of the engineered substrate. For the first time, in order to provide a simple and portable colorimetric/spectrophotometric recognition system to sensitive determination of DPX, an optimized pump-less microfluidic paper-based colorimetric device (μPCD) was introduced and validated for the real-time biomedical analysis of this analyte. According to the obtained results, this alternative approach is suitable for therapeutic drug monitoring (TDM) and biomedical analysis by miniaturized and cost-beneficial devices.

Ultra-sensitive mercury detection from surface wrapping of carbon dots reduced and decorated silver nanoparticles on SERS fiber probes

Highly selective and sensitive detection of toxic mercury ions (Hg2+) has become a critical issue in recent decades, due to increasing environmental and health requirements. Herein, carbon dots reduced and decorated Ag (CDs/Ag) nanoparticles based fiber probes were fabricated, providing a “turn-off” surface-enhanced Raman spectroscopy (SERS) for low-concentration Hg2+ ions detection. The CDs/Ag nanoparticles fiber probe exhibits better SERS performance than that of Ag nanoparticles fiber, attributed to the stronger electromagnetic intensities induced by localized surface plasmon resonance (LSPR) and larger hot-spot areas resulting from the interaction between silver nanoparticles and carbon dots, under 532 nm beam excitation. As low as 10−11 M Hg2+ ions can be detected through the decrease in Raman scattering intensities of CV molecules, due to the SERS inactive Hg metal layer wrapping the surface of silver nanoparticles, through the reduction of Hg2+ ions by carbon dots. The dropping of silver nanoparticles’ LSPR induced absorption peak, EDS elemental mapping, and XPS analysis all confirm that the wrapping decreases the LSPR effect and corresponding Raman intensity. Furthermore, the detection shows high selectivity and can only be applied for detecting Hg2+ ions, owing to the reduction capability of carbon dots. The close analysis results obtained using SERS fiber probes and commercial inductively coupled plasma-mass spectrometry (ICP-MS) for detecting Hg2+ ions in real water sample confirm the reliability of this detection method. This research indicates the CDs/Ag fiber probe has a great potential application for environmental Hg2+ ions detection.

Molecularly imprinted nanoparticles doped graphene oxide based electrochemical platform for highly sensitive and selective detection of L-tyrosine

A highly sensitive and selective electrochemical sensor was developed using a surface modified glassy carbon electrode (GCE) through molecularly imprinted polymerization on the surface of vinyltrimethoxysilane (VTMS) coated magnetic nanoparticle (Fe3O4) decorated silver nanoparticles incorporated graphene oxide, GO (VTMS-Fe3O4/AgGO) for L- Tyrosine (Tyr) detection. A molecular imprinting technique based on free radical polymerization was applied to synthesize molecularly imprinted Methacrylic acid (MAA) and Acrylamide (AA) grafted VTMS-Fe3O4/AgGO polymer (MAA/AA-g- VTMS-Fe3O4/AgGO) designated as MIP and non-imprinted polymer (NIP). The structure and morphology of the prepared polymers were FTIR, XRD, FE-SEM and VSM. MIP and NIP were chosen for modifying the GCE surface by drop casting process to construct the sensors and their electrochemical properties were characterized via EIS and CV. Compared with NIP/GCE sensor, MIP /GCE sensor exhibits excellent sensing response towards Tyr with a wide linear range of 0.25 × 10−13 M to 0.10 × 10−3 M and the limit of detection and limit of quantification as 0.15 × 10−13 M and 0.50 × 10−13 M, respectively with R2 value of 0.9934 by DPV technique. Moreover, MIP/GCE sensor exhibits long-time storage, excellent selectivity and good stability in multiple cycle usage. The practical applicability of MIP/GCE sensor was tested in human blood serum sample. The recovery percentage was obtained between 98.8% and 106.0% with a relative standard deviation (RSD) between 1.01% and 1.59%. Results of the investigations revealed the clinical applicability of the MIP/GCE sensor.

In-situ reduction of AgNPs on MXene surfaces for synthesis of efficient thermally conductive composites with powerful electromagnetic shielding capabilities

Thermally conductive materials are crucial for stable operation of integrated circuits, and there is high interest in improving the thermal conductivity of MXene. This study develops a facile method to enhance the chelating and reducing abilities of MXene towards metal ions by coating a thin layer of polydopamine onto the MXene surface, followed by decoration of silver nanoparticles on the nanosheet surface through in-situ reduction. Naturally abundant nanocellulose fibers were used as the matrix, and continuous thermal pathways were constructed between the fibers by vacuum filtration of the prepared nanofillers. The essential role of AgNPs in providing efficient thermal conductive networks was analyzed using the finite element analysis software. The prepared composite films exhibited an in-plane thermal conductivity up to 7.31 W/m K and demonstrated superior temperature control in heat dissipation tests. At a filler mass fraction of 30 wt%, the average electromagnetic shielding effectiveness of the film with a thickness of 0.17 mm was measured to be 25.8 dB in the X-band, which exceeds the target value for commercial applications. The outstanding performance of the composite paper has demonstrated the great potential of silver-decorated MXene for widespread application in fields such as electronic devices, aerospace, and aviation.

Silver-Decorated and Silica-Capped Magnetite Nanoparticles with Effective Antibacterial Activity and Reusability.

Fruits are safe, toxin-free, and biomolecule-rich raw materials that may be utilized to decrease metal ions and stabilize nanoparticles. Here, we demonstrate the green synthesis of magnetite nanoparticles which were first capped with a layer of silica, followed by the decoration of silver nanoparticles, termed Ag@SiO2@Fe3O4, by using lemon fruit extract as the reducing agent in a size range of ∼90 nm. The effect of the green stabilizer on the characteristics of nanoparticles was examined via different spectroscopy techniques, and the elemental composition of the multilayer-coated structures was verified. The saturation magnetization of bare Fe3O4 nanoparticles at room temperature was recorded as 78.5 emu/g, whereas it decreased to 56.4 and 43.8 emu/g for silica coating and subsequent decoration with silver nanoparticles. All nanoparticles displayed superparamagnetic behavior with almost zero coercivity. While magnetization decreased with further coating processes, the specific surface area increased with silica coating from 67 to 180 m2 g-1 and decreased after the addition of silver and reached 98 m2 g-1, which can be explained by the organization of silver nanoparticles in an island-like model. Zeta potential values also decreased from -18 to -34 mV with coating, indicating an enhanced stabilization effect of the addition of silica and silver. The antibacterial tests against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) revealed that the bare Fe3O4 and SiO2@Fe3O4 did not show sufficient effect, while Ag@SiO2@Fe3O4, even at low concentrations (≤ 200 μg/mL), displayed high antibacterial activity due to the existence of silver atoms on the surface of nanoparticles. Furthermore, the in vitro cytotoxicity assay revealed that Ag@SiO2@Fe3O4 nanoparticles were not toxic to HSF-1184 cells at 200 μg/mL concentration. Antibacterial activity during consecutive magnetic separation and recycling steps was also investigated, and nanoparticles offered a high antibacterial effect for more than 10 cycles of recycling, making them potentially useful in biomedical fields.

Photocurrent Polarity Switching and Enhanced Photoresponse in Silver Nanoparticles Decorated a-GaN-Based Photodetector

The photodetection properties of a-GaN nanorods-based photodetector and the effect of decorating silver nanoparticles are reported. For the pristine a-GaN detector, a surprising phenomenon of negative photoconductivity is observed, explained on the basis of defect states present in GaN nanorods. After the introduction of nanoparticles, the device exhibits reversal in the photocurrent polarity. The photoresponsivity reverses its sign from −0.12 A/W (bare a-GaN) to +6.75 A/W, with the introduction of nanoparticles (wavelength: 355 nm, 4.9 V bias). This current reversal and enhanced performance have been rationalized by considering passivation of surface defect states, resulting into significantly reduced dark current in the hybrid detector.

A strategy to improve dielectric permittivity of Mg–Zn ferrite by using silver nanoparticles

In this work, we used silver nanoparticles (Ag NPs) to enhance the dielectric properties of magnesium-zinc ferrite (Mg–ZnFe2O4) by enhancing local electric field with the creation of nano/micro capacitors between conducting metal particles (Ag NPs) and insulating host (Mg–ZnFe2O4). Mg–ZnFe2O4 was synthesized using the sol-gel method and silver NPs were decorated on magnesium zinc ferrite (Ag@Mg–ZnFe2O4) by employing a sonication approach. The effect of Ag NPs concentration was studied on the structural, morphological, optical, dielectric, and magnetic properties of Ag@Mg–ZnFe2O4 nanocomposite. X-ray diffraction (XRD) confirmed the presence of cubic Mg–ZnFe2O4 and face-centred cubic (FCC) Ag NPs in Ag@Mg–ZnFe2O4 nanocomposite. The structural parameters such as lattice strain, crystallite size and microstrain were correlated with Ag NPs concentration. The morphological study of Ag@Mg–ZnFe2O4 showed uniform decoration of silver at low concentrations; higher concentrations of silver led to reduced covering due to the agglomeration tendency of Ag NPs. Diffused reflectance spectroscopy (DRS) was employed to estimate the effect of Ag NPs on the optical bandgap of Mg–ZnFe2O4. The bandgap narrowing was observed due to the overlapping of the Ag conduction band with the valence band of Mg–ZnFe2O4. All Ag@Mg–ZnFe2O4 samples showed superparamagnetic behaviour and the saturation magnetization was decreased with the increase in the non-magnetic Ag nanoparticles in the nanocomposite. Impedance spectroscopy (IS) was employed to comprehensively analyze the dielectric properties of Ag@Mg–ZnFe2O4. Complex impedance plane plots confirmed the involvement of relaxation phenomena related to grains and grain boundaries in the observed dielectric properties. The decoration of silver nanoparticles was associated with the realization of a high dielectric constant (∼104) in all prepared samples at low frequency. Moreover, uniform decoration of silver was found to show a more stable dielectric constant with relatively low dielectric loss.

A novel portable immuno-device for the recognition of lymphatic vessel endothelial hyaluronan receptor-1 biomarker using GQD-AgNPrs conductive ink stabilized on the surface of cellulose.

Lymphatic vessel endothelium expresses various lymphatic marker molecules. LYVE-1, the lymphatic vessel endothelial hyaluronan (HA) receptor, a 322-residue protein belonging to the integral membrane glycoproteins which is found on lymph vessel wall and is completely absent from blood vessels. LYVE-1 is very effective in the passage of lymphocytes and tumor cells into the lymphatics. As regards cancer metastasis, in vitro studies indicate LYVE-1 to be involved in tumor cell adhesion. Researches show that, in neoplastic tissue, LYVE-1 is limited to the lymphovascular and could well be proper for studies of tumor lymphangiogenesis. So, the monitoring of LYVE-1 level in human biofluids has provided a valuable approach for research into tumor lymphangiogenesis. For the first time, an innovative paper-based electrochemical immune-platform was developed for recognition of LYVE-1. For this purpose, graphene quantum dots decorated silver nanoparticles nano-ink was synthesized and designed directly by writing pen-on paper technology on the surface of photographic paper. This nano-ink has a great surface area for biomarker immobilization. The prepared paper-based biosensor was so small and cheap and also has high stability and sensitivity. For the first time, biotinylated antibody of biomarker (LYVE-1) was immobilized on the surface of working electrode and utilized for the monitoring of specific antigen by simple immune-assay strategy. The designed biosensor showed two separated linear ranges in the range of 20-320 pg ml-1 and 0.625-10 pg ml-1, with the acceptable limit of detection (LOD) of 0.312 pg ml-1. Additionally, engineered immunosensor revealed excellent selectivity that promises its use in complex biological samples and assistance for biomarker-related disease screening in clinical studies.

Capillary Tube Surface-Enhanced Raman Scattering Substrate and High-Sensitivity Molecule Detection

Surface-enhanced Raman scattering (SERS) greatly improves molecule sensitivity compared with ordinary Raman spectroscopy. To excite and detect SERS efficiently, we fabricated glass-made microcapillary tubes decorated with silver nanoparticles inside them. The capillary tubes work as sample containers, where the required sample volume is in the order of a few nanoliters. The capillary tubes also play the role of optical waveguides. The tubes guide the excitation laser light through them so that the light illuminates whole silver nanoparticles inside the tubes at once. The tubes guide the SERS light to the tube end efficiently. The decoration of silver nanoparticles inside the tubes was performed by the silver mirror reaction. By making the tubes thinner and longer, highly sensitive SERS spectroscopy can be achieved. Our method would be a powerful tool for high-sensitivity molecule detection where the sample volume and concentration are extremely low.

Facile preparation of silver nanoparticle decorated RGO nanostructures with enhanced simultaneous detection property for hydroquinone and catechol

Well-dispersed reduced graphene oxide (RGO) nanostructures with uniform decoration of silver nanoparticles (AgNPs) on them have been prepared through a hydrothermal process followed by the freeze-drying method. The obtained graphene-layer-like structure with uniform distribution of AgNPs have then been applied on the glassy carbon electrodes (GCE) to detect different concentration of hydroquinone (HQ) and catechol (CC) in their mixed solutions. Because of such well-dispersed structure and uniform distribution of AgNPs, the AgNPs/RGO/GCE illustrated enhanced simultaneous detection performance for HQ and CC. In the HQ and CC mixed solution with pH of 6.0, the AgNPs/RGO/GCE electrode exhibits a wide linear range of HQ (0.18–130 μM) and CC (0.07–120 μM), and accurate limit of detection (2.37 × 10−2 μM for HQ and 5.8 × 10−2 μM for CC). Thus, it is believed that the AgNPs/RGO nanostructures shows a great potential of applying as possible probes for simultaneous detection of HQ and CC in real environment.

Tailorable Electronic and Electric Properties of Graphene with Selective Decoration of Silver Nanoparticles by Laser-Assisted Photoreduction.

While graphene shows great potential for diverse device applications, to broaden the scope of graphene-based device applications further, it would be necessary to tune the electronic state of graphene and its resultant electrical properties properly. Surface decoration with metal nanoparticles is one of the efficient doping methods to control the properties of two-dimensional materials. Here, we report the p-type doping effects in single-layer graphene decorated with silver nanoparticles (AgNPs) that were formed area-selectively by the facile one-step photoreduction (PR) process based on focused-laser irradiation. During the PR process, AgNPs were reduced on graphene in AgNO3 solution by laser-driven photoexcitation followed by chemical reactions. Based on scanning electron microscopy analyses, the morphology characteristics of AgNPs were shown to be modulated by the laser dwell time and power controllably. Further, p-type doping effects were demonstrated using graphene-field-effect transistor structures whose graphene channels were selectively decorated with AgNPs by the PR process, as validated by the decrease in channel resistance and the shift of the Dirac point voltage. Moreover, the growth of AgNPs was observed to be more active on the graphene channel that was laser-annealed ahead of the PR process, leading to enhancing the efficiency of this approach for altering device characteristics.