A triclosan turn-ON fluorescence sensor based on thiol-capped core/shell quantum dots

Eco-friendly monitoring of triclosan as an emerging antimicrobial environmental contaminant utilizing electrochemical sensors modified with CNTs nanocomposite transducer layer

Environmental appearance of antimicrobials due to frequent use of personal care products as recommended by WHO can cause serious flare-up of antimicrobial resistance. In this work, three eco-friendly microfabricated copper solid-state sensors were developed for measuring triclosan in water. Multi-walled carbon nanotubes were incorporated in sensor 2 and 3 as hydrophobic conductive inner layer. Meanwhile, β-cyclodextrin was incorporated in sensor 3 as an ionophore for selective binding of TCS in presence of interfering compounds. The obtained linear responses of sensors 1, 2 and 3 were (1 × 10- 8-1 × 10- 3 M), (1 × 10- 9-1 × 10- 3 M) and (1 × 10- 10- 1 × 10- 3 M), respectively. Limit of detection was 9.87 × 10- 9 M, 9.62 × 10- 10 M, and 9.94 × 10- 11 M, respectively. The miniaturized sensors were utilized for monitoring of triclosan in water samples.

Subppb level monitoring and UV degradation of triclosan pollutants using ZnO multipod and Ag nanocomposites

A unique nanomaterial platform was developed for trace detection and efficient degradation of triclosan (TCS). A facile spectroscopic technique for surface-enhanced Raman scattering (SERS)-supported identification and ultraviolet (UV) degradation of TCS using a SERS template based on silver spherical nanoparticle (AgNP)-modified ZnO multipods (ZnO@Ag) is reported. Core-shell composite materials of ZnO multipods with a dimension of around 3 μm and AgNPs with an average diameter of ∼27 nm was designed not only as a substrate for TCS degradation up to ∼92% upon UV irradiation (λ = 365 mm, 300 μW/cm²) but also as a monitoring platform sensitive to TCS at a detection limit as low as 10^-9 M (≈0.3 ppb). Herein, the first investigation into ZnO@Ag bimetallic composites is established for both the SERS-based detection and UV-assisted degradation of environmental TCS pollutants. The calibration curve was estimated to be linear at R² > 0.97. The validated technology was successfully used to determine the antibacterial agent and TCS in distilled or river water. The advantages of the ZnO@Ag template are highlighted over conventional detection and excellent degradation.

Smartphone-based colorimetric determination of triclosan in aqueoussamples after ultrasound assisted-dispersive liquid-liquid microextraction under optimized response surface method conditions

In the present study, a simple and low cost methodology based on ultrasonic assisted-dispersive liquid-liquid microextraction (UA-DLLME) followed by smartphone-based colorimetric measurement was introduced for the separation and determination of Triclosan (TCS) from contaminated waters. This method is based on the formation of an azo compound from the alkaline reaction of TCS with a diazonium ion, resulting from the reaction of sodium nitrite and p-sulfanilic acid in an acidic medium. The orange-brown color product was extracted into a low volume of organic phase by UA-DLLME method and RGB values were recorded with free Android app Color Grab. The effective parameters in this procedure, namely solution pH, p-sulfanilic acid and nitrite concentration, reaction time and volume of the extraction solvent were investigated and optimized by response surface methodology (RSM) based on a Box-Behnken design (BBD) model. Under optimum conditions, the calibration graph was linear in the range of 3.0 and 200 μg L^-1 of TCS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.8 and 2.7 μg L^-1, respectively. The proposed method was successfullyused for the analyses of triclosan in several water and wastewater samples and satisfactory results were obtained.

Sensitive Derivative Synchronous and Micellar Enhanced Ecofriendly Spectrofluorimetric Methods for the Determination of Atenolol, Diclofenac, and Triclosan in Drinking Tap Water

BACKGROUND

Nowadays, emergence of unexpected contaminants in drinking water is a challenging environmental problem facing humanity.

OBJECTIVE

Two eco-friendly spectrofluorimetric methods were proposed for the determination of three unexpected contaminants in drinking tap water.

METHODS

The first method is first derivative synchronous spectrofluorimetric method which was developed for simultaneous determination of atenolol (ATN) and diclofenac (DCF) without prior separation at Δλ = 70 nm and at Δλ = 80 nm for ATN and DCF, respectively. The second method was based on using sodium dodecyl sulfate (SDS) as fluorescent enhancer of triclosan (TCS) native fluorescence. TCS exhibits enhanced fluorescence at λ emission = 600 nm upon excitation at λ excitation = 299.4 nm. Solid phase extraction was carried out in both methods.

RESULTS

Linear calibration curves were obtained in concentration range of (4-3000 ng/mL) for ATN and (4-2000 ng/mL) for DCF, by measuring first derivative signal of fluorescence at 300 nm and 375.2 nm, respectively. TCS exhibits linear range (0.1-1 ng/mL) at 600 nm. Mean percentage recoveries were 101.04 ± 0.571, 99.66 ± 1.443, and 99.73 ± 0.566 for ATN, DCF, and TCS, respectively.

CONCLUSIONS

Validation of both methods were performed according to the International Conference on Harmonization guidelines. Results obtained were statistically compared with published methods and no significant differences were found. The proposed methods' greenness is evaluated using analytical Eco-scale and Green Analytical Procedure Index. A greenness comparison with previously published methods has been performed.

HIGHLIGHTS

Both methods were found to be eco-friendly and were successfully applied for the determination of the emerging contaminants in drinking tap water.

In situ monitoring of triclosan in environmental water with subnanomolar detection limits using eco-friendly electrochemical sensors modified with cyclodextrins

The environmental emergence of unexpected contaminants has gained the attention of the scientific community. A broad spectrum antimicrobial compound named triclosan (TCS) was detected in the environment as an emerging contaminant. Owing to its inherent toxicity, we have proposed eco-friendly potentiometric liquid state sensors to be used for monitoring and quantifying TCS in environmental water samples. The proposed sensors have been optimized by modifying the inner filling solution using hydrophilic 2-hydroxypropyl β-cyclodextrin as a complexing agent to be capable of minimizing the trans-membrane ion flux and hence improving the selective and sensitive determination of TCS in environmental matrices with low LOD values. The obtained linear response of the optimized sensor was (1 × 10^-9 to 1 × 10^-5 M) compared to the control sensor (1 × 10^-8 to 1 × 10^-4 M). The obtained limit of detection (LOD) value was found to be 9.86 × 10^-10 M compared to 9.78 × 10^-9 M of the control sensor. The modification of the inner filling solution of the sensor with 2-hydroxypropyl β-cyclodextrin improves not only its sensitivity but also its response time to be only 5 seconds. The electrical performance of the proposed sensor was evaluated following IUPAC recommendations. Both the pH and temperature effects were studied and optimized. Two different greenness assessment tools, Analytical Eco-scale and Green Procedure Index, were adopted upon the evaluation of the proposed sensors' greenness.

A dual luminescent sensor coordination polymer for simultaneous determination of ascorbic acid and tryptophan

Simultaneous high sensitivity detection of biomolecules is important for research in medicine, living cells and environmental samples. In this work, a water stable coordination polymer, [Cd₂(bptc)(4,4'-bpy)(H₂O)₃]ˑH₂O 1 (H₄bptc = 2,3,3',4'-biphenyl tetracarboxylic acid, 4,4'-bpy = 4,4'-bipyridine), was designed and successfully synthesized as a luminescent sensor for simultaneous recognition of Ascorbic Acid (AA) and L-Tryptophan (L-Trp) based on luminescent -OFF and -ON, respectively. Importantly, the proposed sensing system showed an excellent performance with high K_SV values of 4.85 × 10⁴ M^-1, 9.60 × 10⁷ M^-1 and low limit of detection (LOD) of 0.28 nM, 63 nM, respectively. In addition, the probable mechanisms are also discussed. The luminescent quenching behavior by AA can be mainly attributed to the static resonance energy transfer between complex 1 and the analytes. Whereas the enhancing effect of L-Trp comes from the intrinsic strong luminescence for L-Trp itself and photo-competitive mechanism between CP 1 sensor and L-Trp, supposedly. In addition, the repeatability of both systems were also investigated.

A novel strategy for selective removal and rapid collection of triclosan from aquatic environment using magnetic molecularly imprinted nano-polymers

Triclosan (TCS) is a kind of chronic toxicity to aquatic organisms. Due to its highly effective antimicrobial, TCS has been widely applied in personal-care products, which naturally poses a potential risk to the ecological system and human health since its release into water-ecological environment. Therefore, it urgently demands a selective, easily separated, recyclable, and low-cost adsorbent to remove the residues of TCS from aquatic environments. In this study, a novel magnetic molecularly imprinted nano-polymers (TMIPs) were prepared for selective adsorption and convenient collection of TCS in aquatic samples, based on a core-shell technique using TCS as template molecule and SiO₂-coated Fe₃O₄ nanoparticles as the support substrate. The functional groups, particle size, morphology and magnetic property of TMIPs were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy and vibrating sample magnetometer, respectively. The obtained TMIPs possessed excellent adsorption capacity (Q_e = 53.12 mg g^-1), speedy adsorption equilibrium time (2 min) and high selectivity (k' = 6.321) for TCS. Moreover, the pH-tolerance and stability tests manifested that the adsorption capacity of TMIPs for TCS was acid-resistance and could retain 94.2% of the maximum Q_e after 5 times removal-regeneration cycles. The feature of magnetically susceptibility can simplify the procedures of sample handling in TCS determination, because the TMIPs of TCS are easy to be recycled from aquatic samples. As an application demonstration, the toxicity test in microalgae confirmed that a tiny amount of TMIPs could significantly eliminate the toxic effect of TCS on Chlamydomonas reinhardtii via the efficient binding with TCS.

An Immunoaffinity Purification Method for the Simultaneous Analysis of Triclocarban and Triclosan in Foodstuffs by Liquid Chromatography Tandem Mass Spectrometry

Triclocarban (TCC) and triclosan (TCS) have been simultaneously detected in five kinds of foodstuffs using an immunoaffinity purification method coupled with ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) for the first time. Two highly specific monoclonal antibodies against TCC and TCS were produced and coupled to N-hydroxysuccinimide-activated Sepharose 6B gel to prepare the immunosorbent. Under the optimal conditions, mean recoveries from spiked samples by the IAC-UHPLC-MS/MS method were 70.1-92.8% for TCC and 76.6-102.5% for TCS. Intraday relative standard deviations were below 14.5%. The limits of quantification (LOQs) of TCC were 1 ng/L for beverage samples and 0.01-0.02 μg/kg for food samples. The LOQs of TCS were 0.03 μg/L for beverage samples and 0.2-0.3 μg/kg for food samples. The applicability of the method has been proven by analyzing TCC and TCS in different samples from supermarkets in Beijing. The proposed method is sufficiently sensitive and reliable for monitoring trace concentrations of TCC and TCS in food samples.

Silicon doped graphene quantum dots combined with ruthenium(iii) ions as a fluorescent probe for turn-on detection of triclosan

In this work, silicon doped graphene quantum dots (Si-GQDs) were prepared and applied for the sensitive and selective fluorescence detection of triclosan (TCS) in combination with Ru³⁺ ions.