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    Antimicrobial nanolayer films of chloroxylenol–carboxyethylchitosan–modified silver nanoparticles for enhanced surgical suture performance
    (2024-07-20)
    Chittratan, Pakawat
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    Chalitangkoon, Jongjit
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    Antimicrobial surgical suture materials incorporating chloroxylenol-carboxyethylchitosan-modified silver nanoparticles (CECSX-AgNPs) were successfully prepared using the Layer-by-Layer (LbL) deposition technique. Chitosan (CS) was covalently affixed with chloroxylenol as hydrophobic functional groups (PCMX), yielding chloroxylenol-chitosan (CSX) and later hydrophilic acrylic acid onto the CSX skeleton, providing a novel water-soluble antimicrobial agent of chloroxylenol-carboxyethylchitosan (CECSX). <sup>1</sup>H NMR confirmed the successful substitution of PCMX and acrylic acid onto CS, with %DS<inf>PCMX</inf> and %DS<inf>AA</inf> of 8.0 and 33.0, respectively. CECSX successfully stabilized AgNPs via the chemical reduction method, resulting in CECSX modified AgNPs. The colloidal solution exhibited a yellowish hue, spherical shape, monodispersity with an average particle size of 4.8 ± 2.4 nm, and a zeta potential value of −20.97 ± 0.03 mV. Minimum inhibitory concentration (MIC) values for CECSX-AgNPs against E. coli (ATCC25922), S. aureus (ATCC25923), and A. baumanii (ATCC19606) were determined as 25, 12.5, and 1.56 mg/L, respectively. Using the LbL deposition technique, CECSX-AgNPs were successfully deposited onto various suture materials including cotton, polyamide, and polypropylene. Remarkably, CECSX-AgNPs coated surgical sutures exhibited the highest bacterial reduction of 99.99 %. These findings underscore the efficacy of CECSX as a high-performance stabilizing agent for AgNPs production, providing outstanding antibacterial activity on diverse surgical suture materials and promoting the wound healing process.
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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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    ; ;
    Chansai, Sarayute
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    A simple, rapid, selective, and sensitive colorimetric sensor based on a disposable cotton swab loaded with Au nanoparticle–modified Cu-chlorophyllin (Au<sup>0</sup>–NPs<inf>CHL</inf>) and creatinine was developed for mercury (II) detection in aquatic environments using smartphone–based RGB analysis. Au<sup>0</sup>–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 Au<sup>0</sup>–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 Au<sup>0</sup>-NPs<inf>CHL</inf> (0.103 ± 0.03 nmol L<sup>−1</sup>) and 25 µL of creatinine solution (40 mg L<sup>−1</sup>) 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 Hg<sup>2+</sup>–contaminated samples for 3 min, allowing Hg<sup>2+</sup> adsorption. Breaking the swab generated pressure differential, which, along with gravity, drove the Au<sup>0</sup>–NPs<inf>CHL</inf> to mix with creatinine. The resulting mixture migrated toward the swab tip by capillary action and reacted with adsorbed Hg<sup>2+</sup> through metallophilic 5d<sup>10</sup>–5d<sup>10</sup> interactions. Creatinine acted as a bridging ligand, inducing Au<sup>0</sup>–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<sup>−1</sup> with a low LOD of 0.82 µg L<sup>−1</sup>. 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 Hg<sup>2+</sup> contamination in environmental samples.
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    Low-cost synthesis of gold nanoparticles from reused traditional gold leaf and its application for sensitive and selective colorimetric sensing of creatinine in urine
    (2020-01-01) ; ;
    Khongkaew, Putthiporn
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    Phechkrajang, Chutima M.
    Background: Gold nanoparticles (Au NPs) are normally prepared using standard gold (III) trichloride which is much expensive and irritant. This work is aimed at demonstrating simple and low-cost synthesis of Au NPs from the reused traditional gold leaf which is cost-free and less toxic. Methods: The reused gold leaf was donated by the local temple. It was digested and used as the precursor for the preparation of the Au NPs by Turkevich method. Poly (vinyl alcohol) (PVA) was em-ployed as a stabilizer. The as-prepared Au NPs were applied for the colorimetric determination of creatinine in urine without any sample pretreatment. Results: Long-term stability of the gold colloids was achieved for at least 3 months. Morphology and purity of the as-prepared Au NPs were the same as the ones prepared from standard gold (III) salt and standard gold foil. Colorimetric response of the Au NPs was linear to the standard creatinine up to 200 mg L<sup>-1</sup>. The limit of detection (0.16 mg L<sup>-1</sup> or 1.41 µM) was enough sensitive for urinary cre-atinine detection in patients with kidney disease. Good recoveries (97-108%) and fast analysis time (3 min) were achieved. The developed method was successfully validated against the HPLC method. Conclusion: Facile and cost-effective synthesis of the Au NPs from the reused traditional gold leaf, was accomplished. The as-prepared Au NPs were successfully applied for the determination of urinary creatinine with high sensitivity and selectivity.
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    New Chitosan-Grafted Thymol Coated on Gold Nanoparticles for Control of Cariogenic Bacteria in the Oral Cavity
    (2022-08-02)
    Chittratan, Pakawat
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    Chalitangkoon, Jongjit
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    ; ;
    Chitosan-grafted thymol (CST) coated on gold nanoparticles has been synthesized and characterized for the design of antimicrobial materials. CST was synthesized via adapting the Mannich reaction, and it acted as the capping agent for the synthesis of gold nanoparticles (AuNPs). The grafting of thymol onto the side chain of chitosan has provided a degree of substitution value (%DS<inf>NMR</inf>) of 10.0%, calculated by nuclear magnetic resonance spectroscopy. UV-visible spectrometry and elemental analysis were used to confirm the successful synthesis of CST through adapting the Mannich reaction. The appropriate concentration of CST for AuNP synthesis was found to be 0.020%w/v. A red-wine colloidal AuNP solution of 2.41-3.30 nM particle size exhibits a strong surface plasmon resonance at 502 nm, which shows negative charges at pH = 9 of -36.37 mV. This result evidenced that the AuNPs showed electrostatic repulsion and CST played a role as a capping agent to provide a good dispersion and stability state. CST coated on the AuNP surface was successfully utilized for the control of cariogenic bacteria in the oral cavity. The results obtained from this study show that the tuning of the capping agent used in the synthesis step strongly influences the latter antimicrobial activity of the nanoparticles against Streptococcus mutans ATCC 25175 and Streptococcus sobrinus ATCC 33402 activity, with an inhibition zone of 15.90 and 14.25 mm, respectively. The average minimum inhibitory concentration values against S. mutans ATCC 25175 and S. sobrinus ATCC 33402 were found to be 25 and 100 mg/L, respectively, whereas the minimum bactericidal concentration values were 100 and 200 mg/L, respectively.
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    Ultrasonic-driven synthesis of Cu-chlorophyllin-stabilized silver nanoparticles for high-efficiency antimicrobial surgical suture coatings
    (2025-12-01)
    Sombutjiraporn, Saran
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    ; ;
    A novel Cu-chlorophyllin-stabilized silver nanoparticle (Ag<sup>0</sup><inf>NPs</inf>-Chl<inf>Cu</inf>) with potent antimicrobial properties was synthesized for the first time using an ultrasonically driven chemical reduction approach. In this approach, Cu-chlorophyllin (Chl<inf>Cu</inf>) acts as a stabilizing ligand, while sodium borohydride functions as the chemical reductant. The formation mechanism of Ag<sup>0</sup>-NPs<inf>CHL</inf> was elucidated, revealing that ultrasonic irradiation facilitates the in situ reduction of Ag (I) and its subsequent incorporation into the Chl<inf>Cu</inf> complex. Four pyrrole rings coordinate with Ag<sup>0</sup><inf>NPs</inf> through four nitrogen atoms, which serve as adsorption sites for the anchorage of Ag<sup>0</sup>-NPs<inf>CHL</inf>. Characterization by XPS revealed the presence of Ag-N bonding involving pyrrole units on the FCC structure of Ag<sup>0</sup><inf>NPs</inf>. Ag<sup>0</sup><inf>NPs</inf>-Chl<inf>Cu</inf> demonstrated a zeta potential of (-) 35.57±3.54 mV with a spherical shape and an average size of 6.72±1.72 nm, resulting in a stable colloidal dispersion with a monodispersed index. The synthesized Ag<sup>0</sup>-NPs<inf>CHL</inf> nanocomposites were subsequently deposited onto polyamide surgical sutures via an electrostatic Layer-by-Layer (LbL) self-assembly technique. The coated sutures exhibited >99.9 % antibacterial efficiency against E. coli (ATCC25922), S. aureus (ATCC25923), and A. baumanii (ATCC19606). While nanoparticle accumulation was observed in human primary epidermal keratinocyte (HEKa) cells, no cytotoxic effects were detected in the epidermis. This study highlights the effectiveness of Chl<inf>Cu</inf> as a dual stabilizing and coordinating agent for Ag⁰<inf>NPs</inf>, offering a promising approach for developing antimicrobial surgical materials.
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    Supramolecular electrochemical detection of bisphenol A using a melamine-functionalized reduced graphene oxide modified screen-printed electrode
    (2026-06-01)
    Thammaso, Supinya
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    Kamsong, Wichayaporn
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    Karuwan, Chanpen
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    Saetear, Phoonthawee
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    Detection of bisphenol A (BPA), an endocrine disruptor, requires rapid and reliable methods to ensure water safety. In the current work, we present a supramolecular electrochemical sensor based on a melamine-immobilized reduced graphene oxide-modified screen-printed carbon electrode (Mel-rGO SPE) for the determination of BPA. The sensing design exploits dual supramolecular interactions: hydrogen bonding between melamine's amine groups and BPA's hydroxyl moieties, and π–π stacking between their aromatic rings. While rGO significantly enhances electron transfer, these synergistic effects improve device sensitivity. A Mel-rGO SPE was fabricated using an ink-mixing approach to produce a uniform and robust sensor. BPA detection was performed using cyclic voltammetry, and the anodic peak potential was 0.32 V. The current response provided a good correlation with BPA concentrations in the range of 1–250 μM. The detection limit was low, 0.23 μM. The Mel-rGO SPE was successfully applied to determine BPA in polycarbonate bottled water. These promising results indicate that the developed sensor is an alternative device for rapid screening of BPA contamination of water samples.
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    Ultrasensitive electrochemical aptasensors based on trimetallic AuPt-Ru nanoparticles decorated RGO with disposable and low-cost goldleaf electrode for aflatoxin B1 quantification in agricultural products
    (2025-01-01)
    Khattiya, Akrarath
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    Karaket, Ratchanok
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    Due to the significant increase in cases of liver cirrhosis and hepatocellular carcinoma associated with the agricultural products consumption contaminated with Aflatoxin B1 (AFB1), there is an urgent need for rapid AFB1 detection methods. Herein, we propose using waxberry-like heterostructure AuPt-Ru nanoparticles supported by RGO (AuPt-Ru/RGO) embedded goldleaf as a disposable and low-cost electrode (GLE<inf>AuPt-Ru/RGO</inf>) for electrochemical aptasensor detection of AFB1. The trimetallic AuPt-Ru nanocomposite was synthesized through the ultrasonic-driven chemical reduction method. The AuPt-Ru was integrated with RGO to accelerate the electron transfer and increase the specific immobilizing surface area of the thiol-5′-terminated modified aptamer (aptamer) to target AFB1 on GLE. The electrochemical aptasensor GLE<inf>AuPt-Ru/RGO</inf> shows a highly selective response for AFB1 through specific hydrogen bonding and π-π stacking interactions. The linearity of differential pulse voltammetry (DPV) measurements for AFB1 was 0.3–30.0 pg mL<sup>−1</sup> (R<sup>2</sup> = 0.9972) with a detection limit (LOD) and a quantification limit (LOQ) of 9 × 10<sup>−3</sup> pg mL<sup>−1</sup> and 3.1 × 10<sup>−2</sup> pg mL<sup>−1</sup>, respectively. The developed aptamer-based GLE<inf>AuPt-Ru/RGO</inf> performed effectively in actual samples, with recoveries ranging from 94.6 % to 107.9 % in agricultural products including dried red chili, garlic, peanuts, pepper, and Thai jasmine rice. The fabricated aptamer-based GLE-decorated AuPt-Ru/RGO exhibited excellent electrochemical behavior similar to that of a modified commercial electrode, which has great potential application prospects for detecting AFB1 in agricultural products.
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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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    ; ;
    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 (R<sup>2</sup> = 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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    Ultrasonically synthesized core-shell Au/Pt nanoparticles decorated g-C3N4heterostructures for enhanced sunlight-driven photocatalytic degradation of aflatoxin B1 in domestic wastewater
    (2025-10-01) ;
    Peensuwan, Natthakan
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    Paiboonbudsrakum, Tanyapat
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    Chiangthap, Tanawan
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    Chinnawat, Sirinyakorn
    The discharge of domestic wastewater from washing agricultural products contaminated with aflatoxin B1 (AFB1), even at low concentrations, poses significant risks to food chain integrity and public health. Core-shell Au/Pt nanoparticles anchored on a g-C3N4 heterostructure (Au-PtNPs/g-C3N4) were developed as a highly promising photocatalyst for the efficient degradation of AFB1 in domestic wastewater treatment applications. Herein, core-shell Au-PtNPs were synthesized via a straightforward one-step chemical reduction method assisted by ultrasonic irradiation. The core-shell Au-PtNPs (46.52±0.15nm) were uniformly anchored onto the g-C3N4 nanosheets via hydrogen bonding during ultrasonic dispersion. The Au-PtNPs/g-C3N4 composites were systematically characterized and evaluated for AFB1 photodegradation. Complete removal of AFB1 (50μgL-1) was accomplished within just 1min under natural sunlight using 0.50mg of catalyst at pH 7.0, demonstrating a 6.7-fold enhancement over pristine g-C3N4. Mechanistic investigations confirmed that the AuNPs core induced a surface plasmon resonance (SPR) effect that broadened visible-light absorption, while the PtNPs shell served as an efficient electron sink, facilitating charge separation. Simultaneously, the g-C3N4 nanosheets functioned as a visible-light-responsive photoactive scaffold, promoting effective charge generation and directional migration across the heterojunction interface. These synergistic effects were validated by diffuse reflectance UV-vis spectroscopy, linear sweep voltammetry, electrochemical impedance spectroscopy, photoluminescence quenching, and Mott-Schottky analysis. The combined enhancements significantly promoted the generation of reactive oxygen species (•O-2, •OH and h∗), driving the efficient photodegradation of AFB1. Thus, the Au-PtNPs/g-C3N4 photocatalyst provides a promising, sunlight-driven strategy for AFB1 detoxification in real wastewater from domestic, agricultural and food industry sources.
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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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    ; ;
    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 Cu<sup>2+</sup>. Then, the OPD were rapidly oxidized by Cu<sup>2+</sup> 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<sup>−1</sup>. The limit of detection (LOD) and limit of quantification (LOQ) were found at 18.0 µg L<sup>−1</sup> and 62.0 µg L<sup>−1</sup>, 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.