UV Lamp Illumination Research Articles

Green fabrication of fluorescent N-doped carbon quantum dots from Aegle marmelos leaves for highly selective detection of Fe3+ metal ions

This current study uses a simple, environmentally friendly, and economically advantageous Microwave method to create water-soluble carbon dots from Aegle marmelos leaves. Nitrogen-doped carbon dots (N-CQDs) that have been produced exhibit outstanding benefits such as water solubility, biocompatibility, and high stability. Essential characterization methods are used to examine it, including XRD, FTIR, HR-TEM, XPS, UV–vis, and fluorescence spectroscopy. It exhibits excitation-dependent emission behavior, blue emission under UV lamp illumination (wavelength 365 nm), and pH independence. Synthesized N-CQDs with a quantum yield of 14.21 % responded exceptionally well to Fe3+ ions, which causes fluorescence to quench. A single probe fluorescence-based system for detecting Fe3+ ions with high selectivity and sensitivity was designed. Under optimized fluorescence experimental conditions, the linear range of Fe3+ ions was 0–20 μM with a detection limit of 0.184 µM (R2 = 0.99363). The produced N-CQDs respond exceptionally well to Fe3+ ions, which causes fluorescence to quench. This study demonstrates a single probe FL-based device for detecting Fe3+ ions with high sensitivity and selectivity.

Comparison of the Use of Traditional Solvents and Nanosecond 213 nm Nd:YAG Laser in Thinning Naturally Aged Varnish on a Contemporary Oil Easel Painting

The removal of aged varnish on artistic paintings is a delicate intervention and the use of UV laser for this purpose is of special relevance. In particular, the use of nanosecond-pulsed lasers operating at 213 nm has been noted to produce good results in mock-up samples, but it has not been tested in real artworks. In this paper, we report on the application of this procedure for the first time on a contemporary oil easel painting with naturally aged varnish. The obtained results were compared with those achieved using traditional solvents, specifically a mixture of ligroin:acetone. Additionally, hot water was used to remove surface dirt. The performance of the different cleaning procedures was assessed with a range of techniques, including low-power microscopy, UV lamp illumination, laser-induced fluorescence (LIF), and laser-induced breakdown spectroscopy (LIBS). Of the tested treatments, the best performance is obtained by nanosecond laser irradiation at 213 nm using an adequate laser fluence (typically 0.14 J/cm2) that allows controlled and efficient removal of the outermost aged varnish layer without affecting the underlying non-aged varnish and paint layers.

Construction of a novel self-bleaching photochromic hydrogel embraced within the Zn-MOF@WO3 junction for assembling UV-irradiated smart rewritable device

Photochromic hydrogels, which are dynamic in response to external light stimuli, have aroused increasing attentions due to their potential applications in intelligent devices. However, achieving excellent photochromic activity with fast photoresponse and self-bleaching rates still remains a huge challenge. Herein, a novel photochromic junction of zinc-based metal–organic framework (Zn-MOF) and tungsten oxide (WO3) was established as photochromic unit and embraced within hydrogel of poly(acrylic acid-co-polyethylene glycol) [P(AA/PEG)] via the interaction of ionic and hydrogen bonding (denoted as P(AA/PEG)-Zn-MOF@WO3), following by exploiting as self-bleaching photochromic agent for assembling UV-irradiated smart rewritable device. The photoinduced electrons can be efficiently separated and migrated from Zn-MOF to WO3 in the Zn-MOF@WO3 junction after UV irradiation, thereby increasing the coloration degree. Due to the enhanced fast response to light stimuli, the P(AA/PEG)-Zn-MOF@WO3-3 hydrogel prepared using 200 mg Zn-MOF demonstrated the fast responsive photochromic behavior of 10 s under UV lamp illumination and the self-fading process could be easily performed in room condition (within 20 min). Moreover, the coloration degree of P(AA/PEG)-Zn-MOF@WO3-3 photochromic hydrogel was precisely controlled and repeated by changing the UV irradiation time. Consequently, the fast photochromic and self-fading properties of P(AA/PEG)-Zn-MOF@WO3-3 afforded rapid and easy ‘‘writing’’ and “erasing” abilities. The present work proposes a new way for the construction of the reversibly responsive photochromic hydrogel with smart optical materials, further broadening their applications in intelligence sensors, smart windows, and flexible memory devices.

Chirality Transfer from Chiral Mesoporous Silica to Perovskite CsPbBr 3 Nanocrystals: The Role of Chiral Confinement

Chirality Transfer from Chiral Mesoporous Silica to Perovskite CsPbBr ₃ Nanocrystals: The Role of Chiral Confinement

Design and synthesis of highly fluorescent and stable fullerene nanoparticles as probes for folic acid detection and targeted cancer cell imaging

Rational design and construction of fullerene derivatives play significant roles in the development of applications for sensing, marking and imaging in biomedical fields. In the present work, a novel type of C60 fluorescent nanoparticle (C60 FNP) was synthesized by a combination of thiol–ene chemistry and modification with folic acid (FA). The as-prepared C60 FNPs exhibited intense blue luminescence with a relatively high quantum yield of 26%, which is higher than that of any other reported fluorescent fullerene-based nanomaterial. Moreover, they revealed superior photobleaching resistance under constant UV lamp illumination for 5 h and excellent photostablity after 9 months of storage in water. Due to the mutual hydrogen bond interaction, the obtained C60 FNPs were capable of acting as a sensitive and specific probe for FA detection and quantification, with a liner range of 0 to 80 μM and a detection limit of 0.24 μM. Satisfactory recoveries (95.4%–105.2%) were obtained from a series of actual samples, further confirming the feasibility of this nanoprobe. Additionally, taking advantage of the FA moiety, the C60 FNPs had easy access to penetrate into cancer cells with higher expression levels of folate receptors, thereby achieving the function of targeted cellular imaging.

The inherent blue luminescence from oligomeric siloxanes

Luminescent polymers without traditional aromatic groups have attracted great attention due to their excellent biocompatibility and promising applications. Understanding of the luminescence mechanism of such polymers, however, is still in its infancy. To further reveal the fluorescence mechanism in depth, two kinds of oligomeric siloxanes were skillfully elaborated and fabricated via a convenient and facile one-pot transesterification polycondensation reaction under catalyst-free conditions. Intriguingly, oligomeric siloxanes bearing nonconventional chromophores show bright blue fluorescence under 365 nm UV lamp illumination. Our preliminary results demonstrate that oxygen clusters, namely, clustering-triggered emission (CTE), can well explain the inherent fluorescence of oligomeric siloxanes. Moreover, intermolecular hydrogen bonds are conducive to the aggregation of the molecular chains. Then, these bonds will facilitate the formation of oxygen clusters, which produce electron cloud overlap to form the unusual chromophores. In addition, the results suggest that the fluorescence intensity of oligomeric siloxanes enhances with increasing concentration. Furthermore, excitation-dependent emission behavior is observed when varying the excitation wavelength of oligomeric siloxanes. It is also found that the luminescence of oligomeric siloxanes could be effectively tuned by the solvent and metal ions. Oligomeric siloxanes bearing unconventional fluorescence units, i.e., oxygen, amino, and hydroxyl functionalities, show the intrinsic blue fluorescence that results from oxygen clusters, namely, the CTE mechanism. In addition, intermolecular hydrogen bonds are conducive to the aggregation of the molecular chains and the formation of oxygen clusters.

Copper-surrogated galvanic displacement of silver dendrite imprinted on flexible and transparent silk fibroin membrane as a SERS-active substrate and sub-dividable catalyst

By employing copper grid as a surrogate agent, we present a facial, reagent-free and cost-effective approach to imprint the exquisite silver dendroid nanostructures on flexible silk fibroin membrane, which double roles as both optical enhancers and catalytic-active sites over many chemical reactions. Unlike the conventional rigid substrates, this hybrid Ag/protein composite exhibits many previous-inaccessible properties of flexibility, transparency, biocompatibility, molecular permeability and optical manipulation. The galvanic displacement was facilitated by a high pressure uv-lamp illumination (365 nm), shortening the dendroid growth time to be within a few minutes. The resulting substrate was characterized by microscopic image, revealing a decent 3D Ag dendrite architecture and interpenetrated crystal network, which arguably enlarged the entire surface area and keenly regulated the optical/electric property of fibrillated protein film. The underlying principle of copper-initiated silver reduction and growth of crystal structure was discoursed and verified with in-situ spectroscopic interrogation. Moreover, our comprehensive study supports that sub-dividable substrate enables to perform catalytic reaction under a wide range of conditions. This exploration renders a thrust to expand biopolymeric membrane into a wide breadth of applications of bendable devices through chemical modifications, exhaustively and economically.

Utilization of photocatalytic hydrogen evolved (Zn,Sn)(O,S) nanoparticles to reduce 4-nitrophenol to 4-aminophenol

Abstract To reduce 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydrate (NaBH4) in the presence of catalyst has been widely accepted in catalysis field. Many works have claimed that the reduction reaction cannot occur without using NaBH4 as a reducing agent. Herein, we reported the hydrogen evolved Sn(II)-doped Zn(O,S) photocatalyst was synthesized by using precipitation method at 90 °C and then utilized to completely reduce 30 ppm 4-NP to 4-AP under 4 × 6 W UV lamp illumination (0.088 mW/cm2) in 3 h without using NaBH4 as a hydrogen source. It was observed that pure Zn(O,S) nanoparticles did not exhibit a 4-NP reduction, however Zn(O,S) with Sn(II) cation doping showed a 4-NP reduction behavior, as indicated by UV–vis absorbance and HPLC results. The role of Sn(II) doped into Zn(O,S) is considerably important to enhance the amount of photo-induced hydrogen ions for reducing 4-NP to 4-AP on catalyst surfaces.

Enhanced photoelectrochemical performance of TiO2 nanotube arrays with coexisted Pt nanoparticles and Co-Pi cocatalysts

Highly-ordered TiO2 nanotube arrays (TNTAs) were prepared by electrochemical anodization. Cobalt-phosphate (Co-Pi) film fabricated by electrodeposition and Pt nanoparticles (Pt NPs) fabricated by photochemical reduction were decorated onto TNTAs to enhance the photoelectrochemical (PEC) performance together. The photocurrent density of the TNTAs/Co-Pi/Pt photoelectrode could reach 0.185mA/cm2 at 1.23V versus reversible hydrogen electrode under UV lamp illumination (1mW/cm2), which is 2.65 times compared to that of the pure TNTAs photoelectrode. Electrochemistry impedance spectroscopy and Mott-Schottky analysis were conducted to explore the reasons for the enhancement of the PEC performance. Pt NPs could promote the reduction of Co(Ⅳ)-oxo intermediate to Co(II) or Co(Ⅲ) which facilitated the charge transfer in the PEC performance. The result provides a promising guideline to design a simple and efficient photoelectrode for the PEC water-splitting system.

A hydrothermal route to multicolor luminescent carbon dots from adenosine disodium triphosphate for bioimaging

In this work, phosphor and nitrogen co-doped carbon dots (N-P-doped CDs) were developed for bioimaging. The as-synthesized N-P-doped CDs emit a bright blue coloured fluorescence after exposure to a 365nm UV-lamp illumination. It is also demonstrated that the fluorescence of CDs is resistant to the interference of metal ions, saline solution, and high ionic strength environments. The bright fluorescence nature of the N-P-doped CDs has proven them to be excellent probes for cellular imaging. And this guess is further confirmed by using a laser scanning confocal microscope (LSCM). The viability study was carried out by MTT assay, suggesting the high biocompatibility of N-P-doped CDs. The results demonstrated that N-P-doped CDs may be considered as a safe material for bio-imaging and drug delivery in cancer cells.

Investigation of interface property in Al/SiO2/n-SiC structure with thin gate oxide by illumination

The reverse tunneling current of Al/SiO2/n-SiC structure employing thin gate oxide is introduced to examine the interface property by illumination. The gate current at negative bias decreases under blue LED illumination, yet increases under UV lamp illumination. Light-induced electrons captured by interface states may be emitted after the light sources are off, leading to the recovery of gate currents. Based on transient characteristics of gate current, the extracted trap level is close to the light energy for blue LED, indicating that electron capture induced by lighting may result in the reduction of gate current. Furthermore, bidirectional C–V measurements exhibit a positive voltage shift caused by electron trapping under blue LED illumination, while a negative voltage shift is observed under UV lamp illumination. Distinct trapping and detrapping behaviors can be observed from variations in I–V and C–V curves utilizing different light sources for 4H-SiC MOS capacitors with thin insulators.

Fluorescence off-on probe for drug sensing based on graphene oxide’s inherent fluorescence

Drug assay is important particularly considering the mixing of spurious entities in costly antibiotics formulations. Simple and sensitive approaches for purity assay, in that sense, are crucial. Herein, we demonstrate that graphene oxide (GO) as such is an interesting platform for drug assay. We chose amoxicillin (AMX) as a model drug for this study taking into account of its wide spread use. The intense blue fluorescence of GO at the emission wavelength of 460 nm was switched off through fluorescence quenching by Cu2+ ions and the restoration of the fluorescence of GO–Cu2+ system could be achieved by the addition of AMX. The color change was very rapid and could be seen by naked eye under UV lamp illumination at 365 nm. The linear increase in the fluorescence intensity caused by AMX enabled its sensitive detection in the range of 0.01 μM–5.47 μM with a detection limit of 5 nM. The application of the proposed probe was evaluated by estimating AMX in commercial pharmaceutical formulation and in human urine. The developed probe can provide a rapid and simple alternative for the existing spectrophotometry and chromatographic methods for AMX determination.

A ratiometric pH probe for intracellular pH imaging

A ratiometric fluorescence pH probe 2-(N-ethylcarbazole-3-vinyl)-benzothiazole (ECBT) is facilely developed by ethylene bridging of N-ethyl-3-carbazolecarboxaldehyde and benzothiazole, which is a useful fluorescent probe for strongly acidic pH sensing. The pH titration indicates remarkable fluorescence enhancement effect and an emission red-shift of 87nm with pH decreasing from 7.00 to 1.00. Furthermore, the solution color changes from light blue to orange under a UV lamp illumination. A pKa value of 1.62 and a good linearity in the pH range of 1.23–2.10 indicate that the probe can be used in quantitative fluorescence imaging under strongly acidic condition. In addition, ECBT exhibits high selectivity and sensitivity, good photostability and excellent reversibility for pH sensing. The probe is further applied successfully to imaging extreme acidity in Escherichia coli cells without influence of autofluorescence in biological systems.

A new fluorescent enhanced probe based on (E)-9-(2-nitrovinyl)-anthracene for the detection of bisulfite anions and its practical application

A new fluorescent enhanced probe based on (E)-9-(2-nitrovinyl)-anthracene is developed, which shows high selectivity and sensitivity for the detection of bisulfite anions at Na2HPO4 citric acid buffer solutions (pH 5.0). When addition of HSO3−, the fluorescence intensity is significantly enhanced and the probe displays apparent fluorescence color changes from non-fluorescence to blue under a UV lamp illumination, the solution color also changes from yellow to colorless. The detection limit is determined to be as low as 6.30μM. This offers another specific colorimetric and fluorescent probe for bisulfite anions detection, furthermore it is applied in detecting the level of bisulfite in sugar samples.

Simultaneous Determination of Concanavalin A and Peanut Agglutinin by Dual-Color Quantum Dots

In this work, we designed a novel detection strategy to realize simultaneous determination of multiplex lectin by labeling glucosamine (G1) and galactosamine (G2) with different-colored semiconductor quantum dots (QDs). On the basis of the agglutination of the aminosugar-labeled QDs induced by the exclusive binding between the lectin and sugar on the QDs surfaces, the fluorescence emission of the QDs supernatant after centrifugation decreased with relevant lectin concentration [i.e., when concanavalin A (Con A) exists alone], only green color fluorescence emission from QDs-G1 supernatant decreased, so it is peanut agglutinin (PNA) and red color fluorescence emission from QDs-G2. Moreover, since QDs can be simultaneously excited with multiple fluorescence colors and have a larger Stokes shift than organic fluorophores, when both Con A and PNA are present in the sample, both of the green and red color fluorescence emission from QDs-G1 and QDs-G2 supernatant would decrease, thus realizing the simultaneous determination of Con A and PNA. The detection limits of Con A and PNA are 0.30 and 0.18 nM (3σ), respectively. Furthermore, the present detection method not only can determine the protein/lectins by fluorescence spectral method but also can realize visualization detection by UV lamp illumination. To the best of our knowledge, this is the first report of such analytical method in multiple and simultaneous lectin detection.

Metal Complex Polymers for Electroluminescent Applications

AbstractWe report the synthesis and characterization of a soluble metal complex polymer for electroluminescent (EL) applications. The polymer was prepared by the reaction of a zinc Schiff base with 4,4′-diphenylmethane-diisocyanate. The polymer is amorphous and with glass transition temperature of 156 °C and is soluble in common organic solvents such as chloroform, tetrahydrofuran (THF), and N-methylpyrrolidinone (NMP). High optical quality films were obtained by spin-coating the polymer solution of THF. The zinc Schiff base, and the polyurethane (PU) shows strong photoluminescence under a UV-lamp illumination. Single and double layer EL devices consisting ITO/hole transfer layer (HTL)/PU/Al have been fabricated and characterized. The results indicated that the complex polymer could act as both electron transport and emissive layers for EL devices.