Teerasong, Saowapak

Preferred name

Teerasong, Saowapak

Alternative Name

Teerasong, S.

Main Affiliation

School of Science

saowapak.te@kmitl.ac.th

Now showing 1 - 10 of 15

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Poly(vinyl alcohol) capped silver nanoparticles for antioxidant assay based on seed-mediated nanoparticle growth
(2017-08-01)
Teerasong, Saowapak
;
Jinnarak, Amornrassamee
;
Chaneam, Sumonmarn
;
Wilairat, Prapin
;
Nacapricha, Duangjai
A simple and rapid method for measurement of total antioxidant capacity (TAC) was developed. In this work, gallic acid was used as the antioxidant standard. Poly(vinyl alcohol) embedded silver nanoparticles (PVA-AgNPs) were employed as a colorimetric sensor. The detection principle was based on the seed-mediated nanoparticle growth technique. The PVA-AgNPs act as a catalyst in the reduction of Ag+ by gallic acid by providing nucleation seeds. Ag+ was reduced to Ag° and accumulated on the PVA-AgNP surface, leading to an increase in the size of particles. The absorbance of the colloidal solution was drastically enhanced with a small red shift. Under optimal conditions, a linear response was established between the change in absorbance and the TAC value expressed in terms of gallic acid equivalents. The linear range was from 25 to 200 μM with a detection limit of 22.1 μM. Satisfactory precision was obtained with % relative standard deviation (RSD) of 2.17. The developed sensor was successfully applied for TAC assessment of commercial ginger products. The PVA-AgNP sensor offers rapid analysis (within 5 min) compared to other nanoparticle-based antioxidant assays. Synthesis of the particles and assay involved less-toxic chemicals, and is therefore a “greener” method.
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Photoregulation of Gold Nanoparticles Stabilized in a Diacetylenic Nanocapsule
(2017-01-01)
Somjid, Saowalak
;
Chompoosor, Apiwat
;
Kanokmedhakul, Somdej
;
Teerasong, Saowapak
The results of releasing a drug in a burst are unpredictable and one of the inherent drawbacks of using nanocarriers. Here, photoresponsive cationic gold nanoparticles to stabilize diacetylenic nanocapsules enabling photoregulated release of payloads are reported. The fabrication of these nanocapsules relied on an electrostatic interaction of a negatively charged diacetylenic core and a positively charged gold nanoparticle shell. Gold nanoparticles with photoresponsive ligands on their surfaces act as both hydrophobic core stabilizers and gatekeepers of the nanocapsules, while their polydiacetylene cores serve as hydrophobic drug carriers that can be tuned using UV irradiation. The morphology of nanocapsules was analyzed using TEM and dynamic light scattering. The resultant nanocapsules had a spherical shape with an average diameter of 152.9 ± 6.7 nm. Upon UV irradiation, the nanocapsules lost their integrity and an encapsulated model compound was released through diffusion. The release of a hydrophobic molecule was irradiation time dependent and thereby controllable. This light-triggered release provides an alternative strategy for controlled drug delivery.
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A silver nanoparticle thin film modified glass substrate as a colourimetric sensor for hydrogen peroxide
(2015-11-22)
Teerasong, S.
;
Sani, M.
;
Numsawat, P.
;
Martchoo, R.
;
Chompoosor, A.
In this work, a silver nanoparticle (AgNP) coated glass slide was developed as a device for sensing hydrogen peroxide. AgNPs were synthesised using borohydride reduction with a citrate stabiliser, resulting in a negatively charged stabilised particle surface. The particles were attached to the glass surface using the layer-by-layer (LbL) technique. Poly (diallyldimethylammonium chloride) and poly (styrene sulphonate) were used as cationic and anionic polyelectrolyte layers, respectively. The glass slide was modified with polyelectrolytes leaving a cationic layer on the top surface. The AgNPs were subsequently deposited on the slide via electrostatic interaction. As a result, a dark yellow film of AgNPs was obtained with maximum absorption at 410 nm. Film fabrication based on LbL assembly provided acceptable reproducibility (relative standard deviation = 6.5%). The fabricated film had long-term stability (>6 weeks). A very small quantity of AgNPs was used in this method. Fabrication was performed under ambient conditions. Therefore this fabrication was considered as a green method. The AgNP modified slide was developed to sense hydrogen peroxide. Detection is based upon oxidation of AgNPs by hydrogen peroxide. This results in a change in colour of the film from dark yellow to colourless. Linear calibration was obtained over the range of 1.0--100.0 mM of hydrogen peroxide. The device was successfully used for measuring hydrogen peroxide in urine.
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A low-cost method for determination of calcium carbonate in cement by membraneless vaporization with capacitively coupled contactless conductivity detection
(2010-05-15)
Sereenonchai, Kamonthip
;
Teerasong, Saowapak
;
Chan-Eam, Sumonmarn
;
Saetear, Phoonthawee
;
Choengchan, Nathawut
This work presents a flow analysis method for direct quantitation of calcium carbonate in cement without pretreatment of the sample. The method is based on online vaporization of CO<inf>2</inf> gas following acidification of the sample inside a small chamber that has a flow of acceptor solution passing around it. Solubilization of the CO<inf>2</inf> gas into the acceptor stream changes the conductivity of the acceptor solution causing an increase of signal at the capacitively coupled contactless conductivity detection (C4D) placed at the outlet of the vaporization chamber. This chamber is an adaption from previous work reported on 'membraneless vaporization' (MBL-VP). The method can be used in the quality control of production of mixed cement. These cement materials usually have calcium carbonate contents at high concentration range (e.g., 33-99% (w/w) CaCO<inf>3</inf>). Analysis of samples by this method is direct and convenient as it requires no sample pretreatment. The method is low-cost with satisfactory accuracy and acceptable precision. © 2010 Elsevier B.V.
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A novel colorimetric method for detection of gamma-aminobutyric acid based on silver nanoparticles
(2016-06-28)
Jinnarak, Amornrassamee
;
Teerasong, Saowapak
A novel, simple and rapid colorimetric method for determination of gamma-aminobutyric acid (GABA) was developed using a negatively charged citrate-capped silver nanoparticle (AgNP) probe. At an acidic pH of 3.8, GABA had a positive charge due to a protonation of amine groups. Therefore GABA could induce an aggregation of AgNPs due to electrostatic interaction. This caused a decrease in the surface plasmon resonance spectra of the colloidal solution at wavelength of 390 nm with a slight red shift. At the same time, the color of the suspension turned from yellow to green upon aggregation. Quantification of GABA was done spectrophotometrically. Under optimum conditions, the method showed a linear calibration in range of 100-500 mg L-1 GABA, with a detection limit of 57.7 mg L-1. The method was successfully applied to measure GABA quantities in dietary supplements.
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Sequential injection analysis with electrochemical detection as a tool for economic and rapid evaluation of total antioxidant capacity
(2011-06-15)
Chan-Eam, S.
;
Teerasong, S.
;
Damwan, K.
;
Nacapricha, D.
;
Chaisuksant, R.
This work presents a new flow-based coupled electrochemical technique for evaluation of "total antioxidant capacity (TAC)". A sequential injection (SI) with amperometric detection was applied to the TAC analysis of commercial instant ginger infusion beverages using 2,2′-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. Besides having chromogenic properties, the ABTS reagent behaves as an electroactive species at the glassy carbon electrode in phosphate buffer pH 7.0, the decrease of the cathodic current signal of the ABTS+ radical after reaction with antioxidants can be monitored. The SI system, furnished with an in-house electrochemical detection cell (ECD), was optimized with respect to the applied potential, sample and reagent volume, and flow rate to the detector. Gallic acid was used as the standard antioxidant and the capacity was reported as gallic acid equivalent (GAE) unit. TAC measurements of ginger infusions at the optimum condition were performed using the proposed technique and also with the classical batch spectrophotometric ABTS assay. TAC values obtained from our method and the standard method are in good agreement (r2 = 0.956). The SI-amperometric technique provided satisfactory precision (4.11% RSD) with rapid sample throughput (40 samples h-1). Also using this method, the consumption of the expensive ABTS reagent was greatly reduced. © 2011 Elsevier B.V. All rights reserved.
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Gold nanorods enhanced resonance Rayleigh scattering for detection of Hg2+ by in-situ mixing with single-stranded DNA
(2018-02-01)
Ngernpimai, Sawinee
;
Matulakun, Piyaporn
;
Teerasong, Saowapak
;
Puangmali, Theerapong
;
Kopwitthaya, Atcha
A resonance Rayleigh scattering (RRS) method for determination of Hg2+ concentration using positively charged gold nanorods (GNRs) and thymine-rich single-stranded DNA (ssDNA) was developed. Hg2+ can induce a conformation change of ssDNA from a random coil to a hairpin structure via thymine–Hg2+–thymine coordination. Hairpin shaped DNA possesses a high density of negative charges, therefore it caused in a drastic aggregation of GNRs. This resulted in an enhancement of RRS intensity. In this work, a change in RRS intensity proportional to the concentration of Hg2+ was monitored by spectrofluorometer at excitation and RRS wavelengths of 550 nm (λ<inf>ex</inf> = λ<inf>RRS</inf>). This method offered a detection limit of 0.23 nM, which is lower than the maximum mercury contaminant level specified by the US Environmental Protection Agency. Good precision of analysis was obtained (3.1% relative standard deviation). Furthermore, the method was simple, involving in-situ mixing and sensing in a one-pot solution. Detection was accomplished in 5 min. This makes the method advantageous in terms of convenience and rapidity of analysis. The developed method was successfully applied for detection of Hg2+ in tap water samples. Recoveries were found in range of 100.6–119.0%.
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Colorimetric sensor using silver nanoparticles for determination of hydrogen peroxide based on a flow injection system
(2013-09-01)
Teerasong, Saowapak
;
Sonsa-Ard, Thitaporn
;
Vimolkanjana, Chavin
;
Choengchan, Nathawut
;
Chompoosor, Apiwat
In this work, a colorimetric probe using a flow injection (FI) system and silver nanoparticles (AgNPs) was developed for determination of hydrogen peroxide (H2O2) concentration. AgNPs have catalytic ability for decomposition of H2O2, producing silver ions and superoxide. The reaction mechanism of H2O2 and AgNPs at various concentrations is described. H2O2 concentration was quantified by monitoring decrease in AgNPs surface plasmon resonance during the decomposition reaction. Under the optimum condition, the detection limit for H2O2 was 0.6 mg/l. The flow system developed in this study provided good precision of analysis (relative standard deviation = 2.97%) with high throughput (18 samples/h). This method was successfully applied to analysis of H2O2 in pharmaceutical and household products. Therefore, the method is feasible for on-line monitoring H2O2 in manufacturing process quality control. © Copyright 2013 American Scientific Publishers All rights reserved.
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Sequential injection for determination of gamma-aminobutyric acid based on its effect on second order light scattering of silver nanoparticles
(2016-08-01)
Jinnarak, Amornrassamee
;
Anantavichian, Pattarapon
;
Intanin, Apichai
;
Fungladda, Suchada
;
Choengchan, Nathawut
An automated sequential injection (SI) with second order light scattering (SOS) detection for determination of gamma-aminobutyric acid (GABA) was developed. Quantitation is based on electrostatic interaction between GABA and citrate-capped silver nanoparticles (AgNPs). In acetate buffer at pH 3.8, the positively charged GABA induces the nanoparticles to aggregate. This results in a change of light scattering monitored using a spectrofluorometer. In this work, working standard solutions of GABA were prepared in-line by the SI system pumping appropriate volumes of a stock solution of GABA and acetate buffer into a holding coil. Solution of AgNPs was subsequently drawn into the coil. The reaction zone was then transferred to the spectrofluorometer, set with excitation and detection wavelengths at 300 and 600 nm, respectively. Under optimised condition, the SOS intensity was proportional to the concentration of GABA. As a result, a linear curve was obtained in the range of 100–400 mg L−1 GABA, with a lower limit of detection of 39.6 mg L‐1. Good precision of analysis was achieved, with 0.6 and 3.3% relative standard deviation (RSD) for external calibration (n = 5) and standard addition (n = 3), respectively. The developed method was successfully applied for quantification of GABA in dietary supplements (2 samples) and samples of instant green tea (2 samples).
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A simple method based on one phase measurement for determination of the octanol-water partition coefficient of drugs
(2015-01-01)
Teerasong, Saowapak
;
Wattanasin, Panwadee
;
Wilairat, Prapin
;
Nacapricha, Duangjai
The octanol-water partition coefficient (P<inf>ow</inf>) is widely used to assessment of lipophilicity of drug. The Pow can be measured by determining the ratio of the concentration of the drug in octanol to its concentration in water at equilibrium. In the standard method, two calibration curves are required in order to obtain the concentration of drug in the two phases. The procedure is thus tedious and time consuming. In this work, a simple approach for determining the P<inf>ow</inf> of drug is described. Only the absorbance of one phase and volumes of octanol and water are used in the calculation; calibration curves are no longer required, making the procedure much more convenient. The method was applied to examples of hydrophobic and hydrophilic drugs. The P<inf>ow</inf> values obtained by our method agreed well with literature values (R2 = 0.998). This method is simple and capable for screening new drugs in a stage of drug discovery.

Teerasong, Saowapak

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