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Smartphone-based disposable cotton-swab sensor loaded with creatinine/Cu–chlorophyllin–stabilized AuNPs for ultrasensitive RGB colorimetric detection of mercury (II) ions in aquatic environments
(2026-05-01)
Lerdpiriyaskulkij, Natee
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Detsri, Ekarat
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Teerasong, Saowapak
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Chansai, Sarayute
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Mathaweesansurn, Arjnarong
A simple, rapid, selective, and sensitive colorimetric sensor based on a disposable cotton swab loaded with Au nanoparticle–modified Cu-chlorophyllin (Au0–NPs<inf>CHL</inf>) and creatinine was developed for mercury (II) detection in aquatic environments using smartphone–based RGB analysis. Au0–NPs<inf>CHL</inf> were synthesized by ultrasonic-assisted chemical reduction, employing Cu-chlorophyllin as a stabilizing and NaBH<inf>4</inf> as a reducing agent. A vivid red Au0–NPs<inf>CHL</inf> colloidal (7.96 ± 0.29 nm) with a sharp SPR peak at 515 nm was successfully obtained. An aliquot of 75 µL of Au0-NPs<inf>CHL</inf> (0.103 ± 0.03 nmol L−1) and 25 µL of creatinine solution (40 mg L−1) were sequentially loaded into an 8.0 × 0.5 cm cotton swab, separated by a 0.5 cm air gap. Detection began by immersing the swab into Hg2+–contaminated samples for 3 min, allowing Hg2+ adsorption. Breaking the swab generated pressure differential, which, along with gravity, drove the Au0–NPs<inf>CHL</inf> to mix with creatinine. The resulting mixture migrated toward the swab tip by capillary action and reacted with adsorbed Hg2+ through metallophilic 5d10–5d10 interactions. Creatinine acted as a bridging ligand, inducing Au0–NPs<inf>CHL</inf> aggregation and shifting the SPR to 620 nm, causing a visible red-to-blue transition. This sensor enables rapid and visual detection and quantitative evaluation via smartphone RGB analysis. The system demonstrated excellent linearity from 1 to 100 µg L−1 with a low LOD of 0.82 µg L−1. Recoveries of 97.6–101.8 % confirmed high accuracy and minimal matrix interference. The disposable cotton swab RGB sensor provides a rapid, portable, and practical tool for on-site primary assessment of Hg2+ contamination in environmental samples.
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Ultrasonically anchored core–shell Au–Pt nanoparticles on g-C3N4-modified screen-printed carbon electrode for efficient electrochemical detection of diclofenac in aquatic environments
(2026-04-01)
Chinnawat, Sirinyakorn
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Detsri, Ekarat
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Thaipukdee, Piyathida
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Pho-ngernngam, Chakkaphan
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Jindaphet, Phetradar
The widespread occurrence of pharmaceutical residues, particularly diclofenac (DCF), in aquatic environments poses serious ecological and health risks due to their persistence and inefficient removal by conventional treatment systems. This study reports a highly sensitive electrochemical sensor based on a core–shell AuPt nanoparticles (Au0-Pt0<inf>NPs</inf>) decorated graphitic carbon nitride (g-C<inf>3</inf>N<inf>4</inf>) heterostructure modified screen-printed carbon electrode (SPCE) for DCF monitoring. The Au0-Pt0<inf>NPs</inf>/g-C<inf>3</inf>N<inf>4</inf> nanocomposite was prepared using the ultrasonication method, in which ultrasonic energy facilitated hydrogen bonding between the Au0-Pt0<inf>NPs</inf> and g-C<inf>3</inf>N<inf>4</inf> support. The incorporation of Au0-Pt0<inf>NPs</inf> onto the g-C<inf>3</inf>N<inf>4</inf> surface provides strong interfacial adhesion, which effectively enhances charge carrier separation and promotes rapid electron transfer across the interface on the SPCE surface during DCF analysis. Optimization of experimental parameter showed that the electrode fabricated at 1.5 mg mL−1nanocomposite concentration, 15 s interval time analysis, a scan rate of 100 mV s−1and PBS buffer at pH 7.0 exhibited the highest peak current. The Au0-Pt0<inf>NPs</inf>/g-C<inf>3</inf>N<inf>4</inf>/SPCE sensor displayed a wide linear range of 0.25–1000 μmol L−1, which LOD of 0.25 μmol L−1, along with excellent reproducibility (%RSD = 1.12%) and stability (%RSD = 0.24%, after storage for 30 day). The electrode demonstrated strong selectivity against interfering species. Validation with aquatic environments samples achieved recoveries of 98.88–103.49%, and ANOVA analysis confirmed no significant difference (p = 0.527 > 0.05) compared with HPLC results (R2 > 0.99). The synergistic effect of Au0-Pt0<inf>NPs</inf>/g-C<inf>3</inf>N<inf>4</inf> enhanced catalytic performance, making the developed SPCE platform a reliable, and cost-effective sensor for detecting of DCF pollutants.
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Smartphone RGB camera-based colorimetric platform with double-layer spherical Ca (II)-alginate/ZnONPs hydrogel liquid-core curcumin emulsion for rapid and selective detection of pyridoxine (Vitamin B6) in functional beverages
(2025-08-01)
Chinnawat, Sirinyakorn
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Detsri, Ekarat
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Lerdpiriyaskulkij, Natee
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Teerasong, Saowapak
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Mathaweesansurn, Arjnarong
A portable smartphone-based RGB colorimetric sensor was developed for the quantitative detection of pyridoxine (vitamin B6, VB-6) in functional beverages, employing a novel core–shell hydrogel probe (CUR<inf>Hydrogel</inf>), engineered with a calcium alginate matrix encapsulating a liquid-phase curcumin emulsion and externally layered by poly(diallyl dimethyl ammonium chloride)-functionalized ZnO nanoparticles (ZnONPs/PDADMAC). The CUR<inf>Hydrogel</inf> spheres were fabricated via a molecular self-assembly reverse spherification and demonstrated high mechanical stability (stiffness: 6.45 × 104 N/m, compressive strength: 1.01 × 106 N/m2) along with excellent UV-blocking photostability for up to 28 days. The CUR<inf>Hydrogel</inf> probe was applied for detecting VB-6 via a smartphone-based sensing platform. The colorimetric assay was based on a two-step strategy involving initially the formation of the colorless pyridoxine-boron complex by VB-6 and boric acid, after which the remaining boric acid binds with curcumin to produce a red rosocyanine dye. A higher VB-6 concentration yields less rosocyanine and a discernible color shift from orange to yellow, which is quantified via smartphone RGB analysis. The RGB values were assessed via a smartphone application, providing the linearity of VB-6 detection of 10–125 mg L−1 with LOD and LOQ of 2.93 mg L−1 and 9.77 mg L−1. The CUR<inf>Hydrogel</inf> exhibited excellent precision with relative standard deviations (RSDs) ranging from 0.20 to 0.27 %, while recoveries ranged from 99.84 % to 103.03 %. Particularly, the results of this method were also validated by comparing with HPLC and UV–vis spectrophotometry. The smartphone RGB camera-based colorimetric sensor of CUR<inf>Hydrogel</inf> has great potential application prospects for detecting VB-6 in functional beverage samples.
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Ultrasonic-driven chemical reduction synthesis of alizarin complexone-modified gold nanoparticles for dual-signal colorimetric and fluorometric sensing of histamine in seafood products
(2024-12-01)
Phoungsiri, Ampika
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Lerdpiriyaskulkij, Natee
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Mathaweesansurn, Arjnarong
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Detsri, Ekarat
Alizarin complexone-modified gold nanoparticles (Au0-NPs<inf>ALz</inf>) were synthesized using a proposed ultrasonic irradiation-assisted chemical reduction method. Ultrasonic irradiation powers, reaction time and alizarin complexone concentration had been proven to be the main parameters for controlling the nucleation and growth of Au0-NPs<inf>ALz</inf>. In the synthesized ultrasonic irradiation-assisted chemical reduction conditions, Au0-NPs<inf>ALz</inf> had a spherical oriented morphology with a uniform size of 17.84 ± 1.37 nm and are shiny red with a surface plasmon resonance (SPR) of 535 nm. A rapid colorimetric and fluorometric dual-mode detection strategy for selective detection of histamine in seafood was developed based on the self-assembly of Au0-NPs<inf>ALz</inf>-Ni (II) complexes. Ni (II) can capture the histamine molecules close to Au0-NPs<inf>ALz</inf> surfaces, making changes in the colorimetric and fluorometric responses of the solution. The quantitative analysis of histamine was realized through the variation of dual-signal colorimetric and fluorometric responses. Such Au0-NPs<inf>ALz</inf> sensor offered good detection sensitivity for histamine with a detection limit (LOD) of 59.32 μmol L−1 and 116.20 μmol L−1 and wide linear response within the range of 10–10000 μmol L−1 (R2 = 0.9952) and 100–5000 μmol L−1 (R2 = 0.9947) for colorimetric and fluorometric measurement, respectively. Recoveries ranging from 94.99 to 103.29 % and 97.67–106.88 % for colorimetric and fluorometric assay were obtained, showing low levels of matrix effects. Particularly, the results of the dual-mode sensor were also validated by comparing with the HPLC method for improving the assay accuracy and dependability. Ultimately, the developed Au0-NPs<inf>ALz</inf> colorimetric and fluorometric probe performs excellently in practical applications, with promising results for detecting histamine in seafood products.
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Covalent organic frameworks blended cellulose nanocrystal for in-needle syringe solid phase extraction of polycyclic aromatic hydrocarbons in dark roasted coffee
(2024-11-01)
Karaket, Ratchanok
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Khattiya, Akrarath
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Lerdpiriyaskulkij, Natee
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Mathaweesansurn, Arjnarong
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Detsri, Ekarat
A novel solid phase of an in-needle syringe solid-phase extraction system (In<inf>NS</inf>-SPE), covalent organic framework blended cellulose nanocrystal nanocomposite (COF@CNC), was prepared for the adsorption of polycyclic aromatic hydrocarbons (PAHs) in dark roasted coffee samples. Trace PAHs in dark roasted coffee were effectively extracted through π-π stacking interaction with COF@CNC. The effect of various experimental parameters on the extraction performances, including adsorbent dosage, desorption solvent and its volume, sample volume, elution flow rate, and ionic strength, were studied. The extraction efficiency, quantified as extraction recovery, was evaluated using high performance liquid chromatography equipped with fluorescence detection (HPLC-FD). Under the optimal conditions, the COF@CNC sorbent-based In<inf>NS</inf>-SPE with HPLC-FD can be used for detecting four PAHs, including acenaphthene, fluoranthene, phenanthrene, and pyrene, in the linear range of 5 to 1,000 ng mL−1, with a good correlation coefficient (R2 > 0.9968). The detection limits were found in the range of 3.07–5.49 ng mL−1. The COF@CNC sorbent exhibited good reusability (12 times, with a slight change in % recoveries). Furthermore, the proposed In<inf>NS</inf>-SPE based COF@CNC method was environmentally friendly due to the use of a small volume of desorption solvent (1.0 mL). The extraction of PAHs from dark roasted coffee using the developed tool was achieved with recoveries in the range of 82.50–105.76. It proved that the method was unaffected by the sample matrix. Therefore, the COF@CNC nanocomposite sorbent-based In<inf>NS</inf>-SPE is an effective tool for detecting PAHs in dark roasted coffee samples.
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Aggregated gallic acid-modified platinum nanoparticles as colorimetric sensor for tannic acid detection in beverages based on displacement phenomenon
(2024-10-01)
Lerdpiriyaskulkij, Natee
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Mathaweesansurn, Arjnarong
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Monvisade, Pathavuth
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Detsri, Ekarat
A new colorimetric assay for the rapid detection of tannic acid in beverage samples based on displacement phenomenon of aggregated gallic acid-modified platinum nanoparticles is developed for the first time. PtNPs were functionalized with gallic acid, promoting the formation of the green-hued aggregated nanoparticles. While colorimetry offers a rapid method for identifying tannic acid, challenges remain in sensitivity and accuracy of detection on the PtNPs colorimetric probe, particularly in the presence of anthocyanin interferences. To address this, we developed a sample preparation method to degrade anthocyanin in beverages. Tannic acid was easily displaced onto the gallic acid-coated PtNPs surfaces, causing dispersion and resulting in a visible color change from green to orange − brown. Under the optimal conditions, the colorimetric sensor exhibited a linear response in the range of 1 − 2,000 µmol/L (R2 = 0.9991). The limit of detection (LOD) and the limit of quantification (LOQ) were found at 0.02 and 0.09 µmol/L, respectively. The proposed sensor expressed superior selectivity over other interfering substances and demonstrated excellent precision with a relative standard deviation (RSD) of 1.00 %−3.36 %. More importantly, recoveries ranging from 95.0 − 104.7 % were obtained, indicating the capability of proposed colorimetric sensor to detect tannic acid rapidly and accurately in real beverage samples.
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A Ratiometric Fluorescence Amplification Using Copper Nanoclusters with o-Phenylenediamine Sensor for Determination of Mercury (II) in Natural Water
(2023-06-01)
Phoungsiri, Ampika
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Lerdpiriyaskulkij, Natee
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Monvisade, Pathavuth
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Detsri, Ekarat
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Mathaweesansurn, Arjnarong
A simple and rapid method for determining mercury (II) has been developed using L-cysteine-capped copper nanocluster (CuNCs) with o-phenylenediamine (OPD) as the sensor. The characteristic fluorescence peak of the synthesized CuNCs was observed at 460 nm. The fluorescence properties of CuNCs were strongly influenced by the addition of mercury (II). Upon addition, CuNCs were oxidized to form Cu2+. Then, the OPD were rapidly oxidized by Cu2+ to form o-phenylenediamine oxide (oxOPD), as evidenced by the strong fluorescence peak at 547 nm, resulting in a decrease in the fluorescence intensity at 460 nm and an increase in the fluorescence intensity at 547 nm. Under optimal conditions, a calibration curve between the fluorescence ratio (I547/I460) and mercury (II) concentration was constructed with a linearity of 0–1000 µg L−1. The limit of detection (LOD) and limit of quantification (LOQ) were found at 18.0 µg L−1 and 62.0 µg L−1, respectively. The recovery percentage was in the range of 96.8–106.4%. The developed method was also compared with the standard ICP-OES method. The results were found to be not significantly different at a 95% confidence level (t<inf>stat</inf> = 0.365 < t<inf>crit</inf> = 2.262). This demonstrated that the developed method could be applied for detecting mercury (II) in natural water samples.

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