Sensors For Detection Of Metal Ions Research Articles

Facile Green Gamma Irradiation of Water Hyacinth Derived-Fluorescent Carbon Dots Functionalized Thiol Moiety for Metal Ion Detection.

Fluorescent sensor-based carbon dots (CDs) have significantly developed for sensing metal ions because of their great physical and optical properties, including tunable fluorescence emission, high fluorescence quantum yield, high sensitivity, non-toxicity, and biocompatibility. In this research, a green synthetic approach via simple gamma irradiation for the carbon dot synthesis from water hyacinth was developed since water hyacinth has been classified as an invasive aquatic plant containing cellulose, hemicellulose, and lignin. The thiol moiety (SH) was further functionalized on the surface functional groups of CDs as the "turn-off" fluorescent sensor for metal ion detection. Fluorescence emission displayed a red shift from 451 to 548nm when excited between 240 and 500nm. The quantum yield of CDs-SH was elucidated to be 13%, with strong blue fluorescence emission under ultraviolet irridiation (365nm), high photostability and no photobleaching. The limit of detection was determined at micromolar levels for Hg2+, Cu2+, and Fe3+. CDs-SH could be a real-time monitoring sensor for Hg2+ and Cu2+ as fluorescence quenching was observed within 2min. Furthermore, paper test-strip based CDs-SH could be applied to detect these metal ions.

Recent Progress in Membrane based Colorimetric Sensor for Metal Ion Detection

Recent Progress in Membrane based Colorimetric Sensor for Metal Ion Detection

Microalgae living sensor for metal ion detection with nanocavity-enhanced photoelectrochemistry

Metal ions are known to play various roles in living organisms; therefore, the detection of metal ions in water resources is essential for monitoring health and environmental conditions. In contrast to artificially fabricated materials and devices, biological-friendly materials such as microalgae have been explored for detecting toxic chemicals by employing fluorescence emissions and biophotovoltaic fuel cells. However, complicated fabrication, long measurement time, and low sensitivity remain the greatest challenge due to the minimal amount of bioelectricity generated from whole-cell microalgae. Herein we report the novel concept of a microalgae living biosensor by enhancing photocurrent through nanocavities formed between copper (Cu) nanoparticles and the Cu-electrode beneath. The strong energy coupling between plasmon cavity modes and excited photosynthetic fluorescence from Chlorella demonstrated that photoelectrical efficiency could be significantly amplified by more than two orders of magnitude through nanocavity confinement. Simulation results reveal that substantial near-field enhancements could help confine the electric field to the electrodes. Finally, the microalgae sensor was exploited to detect various light and heavy metal ions with a breakthrough detection limit of 50 nM. This study is envisioned to provide inspirational insights on nanocavity-enhanced electrochemistry, opening new routes for biochemical detection, water monitoring, and sustainable optoelectronics.

Fabrication of a dual-emitting dye-encapsulated metal-organic framework as a stable fluorescent sensor for metal ion detection.

Dye-loaded metal organic frameworks (MOFs) are regarded as one of the most fascinating luminescent materials for selective chemical sensing. Herein, a facile two-step synthesis procedure is reported for the successful encapsulation of fluorescein dye into porous zinc-adenine metal-organic framework (bio-MOF-1) crystals, and thus the aggregation-caused quenching of dye molecules can be eliminated in the confined MOF structure to further create dual emission centers. The as-prepared solid state fluorescein@bio-MOF-1 composite exhibits both the characteristic emissions of the fluorescein dye and bio-MOF-1, and host-guest energy transfer also occurs. Particularly, depending on the variety of the luminescence intensities of different metal ions incorporated in fluorescein@bio-MOF-1, such a host-guest system could be used for high-sensitive sensing of metal cations, especially for the drastic luminescence quenching of Fe3+ ions. The quenching effect coefficient (Ksv) for every metal ion detected is calculated, and the largest Ksv value for Fe3+ ions is determined to be 5072 M-1. Such an encapsulation strategy can be widely adopted to design new dye@MOF composites with multiple luminescent centers for metal cation sensing.

Thermo-responsive electrospun nanofibers doped with 1,10-phenanthroline-based fluorescent sensor for metal ion detection

Heavy metal ion pollution is one of the important environmental problems, and many efforts have been devoted to develop highly sensitive sensors for detection of heavy metal ions in environment. In this study, an 1,10-phenanthroline-based fluorescent sensor (F-phen) was synthesized and doped into poly(N-isopropylacrylamide-co-N-hydroxymethyl-acrylamide) (Poly(NIPAAm-co-NMA)) nanofiber films via simple electrospinning technique, where the moieties of NIPAAm and NMA were designed to exhibit thermo-responsive and chemical crosslinking functions, respectively. The electrospun nanofibers prepared from the appropriate composition of NMA in the copolymer (P3) could stabilize their fibrous morphology in aqueous environment. Among different weight ratios of F-Phen doped in nanofibers, P3-3 (3 wt% corresponding to copolymer) showed significant quenching of fluorescence as chelating with Cu2+ ion. The linear Stern–Volmer plot of nanofibers for Cu2+ was observed, and the calculated Stern–Volmer constant (K sv ) was 5.5 × 104 M−1. As compared to dip-coating films, the downward deviation to linear Stern–Volmer plots of thin films was observed, indicating a fraction of F-Phen was inaccessible to the quencher (Cu2+). The enhanced sensitivity of F-Phen-doped electrospun nanofibers is attributed to their higher surface area compared to dip-coating films. In addition, the F-Phen-doped nanofibers also exhibited an on/off switchable sensing behavior. This is due to the hydrophilic–hydrophobic change of PNIPAAm as varying temperature that controlled the metal ions to be accessible to the sensors. All of the results indicate the thermo-responsive electrospun sensing nanofibers not only enhance the sensitivity and have an on–off sensing characteristic, but also provide a simple strategy to design and fabricate effective sensing materials for detection of metal ions.

Nanosized diblock copolymer micelles as a scaffold for constructing a ratiometricfluorescent sensor for metal ion detection in aqueous media

A facile strategy was employed to create a fluorescence resonance energy transfer (FRET) basedratiometric sensing system for ferric ions in all-aqueous media by using nanosized poly(ethylene oxide)-b-polystyrene micelles as the scaffold. A hydrophobic fluorescent dye nitrobenzoxadiazolylderivative (NBD), which served as the energy transfer donor, was incorporated into themicelle core during the micelle formation; a spirolactam rhodamine derivative (SRhB-OH)was chosen as a sensitive and selective sensor for Fe(III) ions and was then ‘adsorbed’ intothe micelle core/corona interface. A highly efficient ring-opening reaction of SRhB-OHinduced by Fe(III) generates the long-wavelength rhodamine B fluorophore which can actas the energy acceptor; thus, the micelle nanoparticles can serve as a FRET-basedratiometric detection system for ferric ions. The effects of PS block length onthe ion sensing performance of the micelles were investigated, and it has beenfound that the micelles formed by the copolymer with moderate block length (PEO113-b-PS115) were preferable as the scaffold for the FRET system and exhibited asensitive and selective sensing capacity for Fe(III) with a detection limit of 1 µM. This nanoparticle-based sensing strategy may be utilized to construct otherratiometric chemosensors by replacing the current dyes with other suitable ones.