Diaminodiphenyl sulfone as a novel ligand for synthesis of gold nanoparticles for simultaneous colorimetric assay of three trivalent metal cations (Al3+, Fe3+ and Cr3+)

Multi-ion detection chemosensor based on rhodamine for turn-on fluorescence sensing and bioimaging of Fe3+, Al3+, Cr3+, and Hg2+ under different channels

A novel rhodamine-based multi-ion fluorescent sensor, RGN, was designed and synthesized for the highly selective detection of mercury ions (Hg2+) in ethanol and water systems, as well as trivalent cations (Fe3+, Al3+, and Cr3+) in acetonitrile and water systems using a two-step Schiff base reaction method. Nuclear magnetic titration experiments and theoretical calculations demonstrated that the sensor achieved the detection of the aforementioned metal ions through the fluorescence turn-on phenomenon induced by lactam ring-opening. Density functional theory (DFT) calculation results showed decreased HOMO-LUMO energy gaps and increased dipole moments, indicating the effective coordination of the sensor with the corresponding metal ions to form more stable complexes, thereby achieving detection objectives. Furthermore, the fluorescence turn-on sensor RGN exhibited relatively low detection limits, with limits of detection (LOD) for Fe3+, Al3+, Cr3+, and Hg2+ being 10.20 nM, 14.66 nM, 58.78 nM, and 73.33 nM, respectively. Finally, practical applications of sensor RGN in environmental water samples, L929 cells, and zebrafish were demonstrated, indicating its potential for detecting and tracking Fe3+, Al3+, Cr3+, and Hg2+ in environmental samples and biological systems, with prospects for biomedical applications in the diagnosis and treatment of heavy metal ion-induced diseases.

Rapid Determination of Cr3+ and Mn2+ in Water Using Laser-Induced Breakdown Spectroscopy Combined with Filter Paper Modified with Gold Nanoclusters

Excessive emissions of heavy metals not only cause environmental pollution but also pose a direct threat to human health. Therefore, rapid and accurate detection of heavy metals in the environment is of great significance. Herein, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with filter paper modified with bovine serum albumin-protected gold nanoclusters (LIBS-FP-AuNCs) for the rapid and sensitive detection of Cr3+ and Mn2+. The filter paper modified with AuNCs was used to selectively enrich Cr3+ and Mn2+. Combined with the multi-element detection capability of LIBS, this method achieved the simultaneous rapid detection of Cr3+ and Mn2+. Both elements showed linear ranges for concentrations of 10-1000 μg L-1, with limits of detection of 7.5 and 9.0 μg L-1 for Cr3+ and Mn2+, respectively. This method was successfully applied to the determination of Cr3+ and Mn2+ in real water samples, with satisfactory recoveries ranging from 94.6% to 105.1%. This method has potential application in the analysis of heavy metal pollution.

Dual-emission ciprofloxacin-gold nanoclusters enable ratiometric sensing of Cu2+, Al3+, and Hg2

An innovative triple optical sensor is presented that utilizes gold nanoclusters (GNCs) stabilized with ciprofloxacin (CIP) and bovine serum albumin (BSA). The sensor is designed to identify three critical metal ions, namely Cu2+, Al3+, and Hg2+. Under 360 nm excitation, the synthesized CIP-BSA-GNCs demonstrate dual fluorescence emission with peaks at 448 nm (blue) and 612 nm (red). The red emission is associated with the interior of the CIP-BSA-GNCs, whereas the blue emission results from the surface-bound CIP molecules. The sensitive and selective fluorescent nanosensor CIP-BSA-GNCs were employed to detect Cu2+, Al3+, and Hg2+ ions. Cu2+ effectively quenched the fluorescence intensity of the CIP-BSA-GNCs at both peaks via the internal charge transfer mechanism (ICT). Cu2+ could be detected within the concentration range 1.13 × 10-3 to 0.05 µM, with a detection limit of 0.34 nM. Al3+ increased the intensity of CIP fluorescence at 448 nm via the chelation-induced fluorescence enhancement mechanism. The fluorescence intensity of the core CIP-BSA-GNCs at 612 nm was utilized as a reference signal. Thus, the ratiometric detection of Al3+ succeeded with a limit of detection of 0.21 nM within the dynamic range 0.69 × 10-3 to 0.07 µM. Hg2+ effectively quenched the fluorescence intensity of the CIP-BSA-GNCs at 612 nm via the metallophilic interaction mechanism. The fluorescence intensity of CIP molecules at 448 nm was utilized as a reference signal. This allowed for the ratiometric detection of Hg2+ with a detection limit of 0.7 nM within the concentration range 2.3 × 10-3 to 0.1 µM.

Tannic Acid-Functionalized Silver Nanoparticles as Colorimetric Probe for the Simultaneous and Sensitive Detection of Aluminum(III) and Fluoride Ions

In this study, we employed tannic acid (TA)-functionalized silver nanoparticles (TA@AgNPs) as colorimetric probe for the simultaneous and sensitive detection of Al(III) and F- ions. The proposed sensor was based on the aggregation and anti-aggregation effects of target Al(III) and F- ions on TA@AgNPs, respectively. Because of the strong coordination bond between Al(III) ions and TA, the addition of Al(III) ions to TA@AgNPs could cause aggregation and, hence, result in a significant change in the absorption and color of the test solution. Interestingly, in the presence of F- ions, the aggregation effect of Al(III) ions on TA@AgNPs can be effectively prevented. The extent of aggregation and anti-aggregation effects was concentration-dependent and can be used for the quantitative detection of Al(III) and F- ions. The as-proposed sensor presented the sensitive detection of Al(III) and F ions with limits of detection (LOD) of 0.2 and 0.19 μM, respectively. In addition, the proposed sensor showed excellent applicability for the detection of Al(III) and F- ions in real water samples. Moreover, the sensing strategy offered a simple, rapid, and sensitive detection procedure and could be used as a potential alternative to conventional methods, which usually involve sophisticated instruments, complicated processes, and a long detection time.

Multiresponsive tetrarylethylene-based fluorescent dye with multicoloreded changes: AIEE properties, acidichromism, Al3+ recognition, and applications

A novel fluorescent sensor BTAE-PA containing two tetrarylethylene (TAE) units linked through pyrimidine-2-amine was prepared, and its optical properties were systematically studied. BTAE-PA exhibited a typical aggregation-induced emission enhancement behavior, and its fluorescent properties could be efficiently modulated by acid/base and metal ions in THF. The protonated effect could induce significant acidichromism and 'turn-on' near-infrared emission with a large Stokes shift (Δλ = 225 nm). Furthermore, BTAE-PA was highly selective toward Al³⁺ with significant absorption (yellow → orange) and fluorescence (green → red) changes. A Job's plot established the 1 : 1 stoichiometry of the complex formation between BTAE-PA and Al³⁺, and the limit of detection for Al³⁺ was determined to be 1.30 × 10^-7 mol L^-1. Finally, we also demonstrated that BTAE-PA could be made into test paper strips for 'naked-eye' detection of acid/Al³⁺, and fluorescence imaging experiments proved that BTAE-PA is capable of achieving cell imaging with good biocompatibility. Therefore, the multi-stimuli-responsive and multicoloured display performance of BTAE-PA endows the material with potential applications in security ink, acid/Al³⁺ sensing, and bio-imaging.

Smartphone-based microfluidic chip modified using pyrrolidine-1-dithiocarboxylic acid for simultaneous colorimetric determination of Cr3+ and Al3+ ions

A portable µ-chip-based colorimetric device was developed for the determination of Cr³⁺ and Al³⁺ ions. The silver nanoparticles were modified with pyrrolidine-1-dithiocarboxylic acid ammonium salt as a novel ligand for the first time. The color of modified AgNPs in the test zone immediately changes after the addition of Cr³⁺ and Al³⁺ ions. The resulting color changes were detected by the naked eye or were taken by a smartphone camera. The obtained images were analyzed by RGB software to assay the Cr³⁺ and Al³⁺ ions concentration. Under optimized experimental conditions, the linear ranges are 0.1-220 and 0.01-250 µM for Cr³⁺ and Al³⁺ ions, respectively. The probe has a limit of detections of 10.66 and 3.55 nM for Cr³⁺ and Al³⁺ in an aqueous solution. In the case of µ-chip, the concentration ranges are 0.1-200 μM and 0.01-220 μM for Cr³⁺ and Al³⁺ ions, with detection limits of 9.18 and 2.30 nM, respectively. The µ-chip showed great potential as a fast detection tool for the monitoring of Cr³⁺ and Al³⁺ ions in real samples such as river water samples.

Novel biogenic silver and gold nanoparticles for multifunctional applications: Green synthesis, catalytic and antibacterial activity, and colorimetric detection of Fe(III) ions

In this study, novel biogenic silver (AgNPs) and gold nanoparticles (AuNPs) were developed using a green approach with Ganoderma lucidum (GL) extract. The optimization of synthesis conditions for the best outcomes was conducted. The prepared materials were characterized and their applicability in catalysis, antibacterial and chemical sensing was comprehensively evaluated. The GL-AgNPs crystals were formed in a spherical shape with an average diameter of 50 nm, while GL-AuNPs exhibited multi-shaped structures with sizes ranging from 15 to 40 nm. As a catalyst, the synthesized nanoparticles showed excellent catalytic activity (>98% in 9 min) and reusability (>95% after five recycles) in converting 4-nitrophenol to 4-aminophenol. As an antimicrobial agent, GL-AuNPs were low effective in inhibiting the growth of bacteria, while GL-AgNPs expressed strong antibacterial activity against all the tested strains. The highest growth inhibition activity of GL-AgNPs was observed against B. subtilis (14.58 ± 0.35 mm), followed by B. cereus (13.8 ± 0.52 mm), P. aeruginosa (12.38 ± 0.64 mm), E. coli (11.3 ± 0.72 mm), and S. aureus (10.41 ± 0.31 mm). Besides, GL-AgNPs also demonstrated high selectivity and sensitivity in the colorimetric detection of Fe³⁺ in aqueous solution with a detection limit of 1.85 nM. Due to the suitable thickness of the protective organic layer and the appropriate particle size, GL-AgNPs validated the triple role as a high-performance catalyst, antimicrobial agent, and nanosensor for environmental monitoring and remediation.

Snail slime-based gold nanoparticles: An interesting potential ingredient in cosmetics as an antioxidant, sunscreen, and tyrosinase inhibitor

Due to their properties, snail slime-based products have been appreciated and used worldwide. So, as an alternative and innovative use of snail slime, it was adopted to induce gold nanoparticles' formation, conferring them interesting properties. By a simple, one-pot, and eco-friendly approach, 14 ± 6 nm wide hybrid gold nanoparticles, having an inorganic metallic core decorated by the slime's main components, were obtained. Among their several properties, their antioxidant and tyrosinase inhibition activity were investigated through the DPPH and ABTS and the tyrosinase assays, respectively. After assessing their non-cytotoxicity in our previous work, the results revealed positive responses, enabling their use as a potential novel multifunctional ingredient in cosmetics. Interestingly, the gold nanoparticle photostability, investigated by means of a solar simulator lamp, suggests using them in commercial cosmetic sunscreen products as a potential alternative to the commonly used inorganic sunscreen ingredients. The theoretical Sun Protection Factor was evaluated, obtaining values in the range 0-12. The proposed environmentally friendly and cost-effective protocol for nanoparticle synthesis, following the principles of Green Chemistry, opens a hugely attractive space toward the study of snail slime-based gold nanoparticles as a potential multipurpose platform in cosmetics.

Simultaneous detection of aqueous aluminum(III) and chromium(III) using Persea americana reduced and capped silver nanoparticles

There is a significant interest to develop sensing devices that detect water toxins, especially heavy metal ions. Although there have already been numerical reports on detecting toxic heavy metal ions, the use of adaptable devices could enable a broader range of sensing applications. Here, we used fresh peel extract (PeA) and dried peel extract (DPeA) of Persea americana (Avocado) as a reducing and capping agent to synthesize and stabilize AgNPs. The dimensions of NPs were controlled by tuning pH, temperature, and volume of the reducing agent. The sensitivity and selectivity of the AgNPs toward various metal ions viz. Ni(II), Cd(II), Al(III), Hg(II), Cr(III), Ba(II), Pb(II), Zn(II), Co(II), Mn(II), Cu(II), Ca(II), Mg(II), and K(I) were studied. The detection probe was found to be selective and sensitive toward Al(III) and Cr(III) ions with the detection limit of 0.04 ppm and 0.05 ppm, respectively. High-resolution transmission electron microscope (HRTEM), ultraviolet-visible (UV-Vis) spectroscopy, and dynamic light scattering (DLS) analysis results confirm an agglomeration-based mechanism for sensing both metal ions. This method can be exploited for the colorimetric detection of toxic heavy metals in real water samples.

Rapid and selective detection of aluminum ion using 1,2,3-triazole-4,5-dicarboxylic acid-functionalized gold nanoparticle-based colorimetric sensor

A highly selective, sensitive, rapid, low-cost, simple and visual colorimetric system for Al³⁺ ion detection was developed based on gold nanoparticles (AuNPs) modified with 1,2,3-triazole-4,5-dicarboxylic acid (TADA). The modified gold nanoparticles (TADA–AuNPs) were first prepared by sodium citrate (Na₃Ct) reduction of chloroauric acid (HAuCl₄) and then capped with a TADA ligand. Five TADA–AuNPs sensors were constructed with sodium citrate (Na₃Ct)/chloroauric acid (HAuCl₄) under different molar ratios. Results showed that the molar ratio of Na₃Ct/HAuCl₄, TADA–AuNPs concentration, pH range and detection time had obvious influences on the performance of this colorimetric method. The optimal detection conditions for Al³⁺ ions were as follows: Na₃Ct/HAuCl4 molar ratio of 6.4 : 1, 0.1 mM of TADA–AuNPs concentration, 4–10 pH range and 90 s of detection time. Under the optimal conditions and using diphenyl carbazone (DPC) as a Cr³⁺ masking agent, this colorimetric sensor exhibited outstanding time efficiency, selectivity and sensitivity for Al³⁺ detection. In particular, the detection limits of this sensor obtained via UV-vis and the naked eye were 15 nM and 1.5 μM, respectively, which were much lower than the current limit (3.7 μM) for drinking water in WHO regulation and better than the previous reports. Moreover, this colorimetric sensing system could be used to for on-site, trace level and real-time rapid detection of Al³⁺ in real water samples.

A colorimetric sensor based on TADA–AuNPs accompanied by a masking agent DPC was constructed, with which the rapid quantification of Al³⁺ can be realized by UV-vis spectroscopy or naked eye observation.