Toemsak Srikhirin

• PhD
• Professor (Assistant) at Mahidol University

Objectives To address the high surface roughness and poor optical properties of three-dimensional (3D) printed orthodontic clear retainers, an alternative post-processing protocol was investigated with the goal of achieving improved surface, optical, and mechanical properties while preserving dimensional accuracy. Materials and methods Samples wer...

A carbon block is a carbonaceous material used in various applications such as bearings, mechanical seals, and electrical brushes. This work aims to fabricate carbon blocks from industrial graphite waste, a residue from the cutting and tooling process of graphite block production. The ball milling process was used to fabricate ultrafine graphite wa...

Nano-enhanced organic phase change material (PCM) composite consists of stearic acid (SA, act as the thermal storage media), graphite powder(GP, function as thermal conductor), and magnesium hydroxide nanoparticles(nMH), micro-sized (MMH), function as the flame retarder), were formulated and investigated for their thermophysical properties and flam...

The preparation of cellulose-based flame retardant paper treated with sodium silicate and silicon dioxide (SiO 2 ) colloidal particle by simple immersion process is reported. Cellulose-based paper was preheated at 90°C for surface preparation. The heat treated paper was immersed in solution of sodium silicate-SiO 2 at different immersion time rangi...

Objective Patients who develop interferon-gamma autoantibodies (IFN-ɤ autoAbs) in adult-onset immunodeficiency (AOID) syndrome are more likely to develop opportunistic and recurrent intracellular infections. The assay to detect IFN-ɤ autoAbs is essential for the diagnosis and therapeutic monitoring of AOID syndrome. Therefore, this study applied th...

This paper demonstrates the use of a smartphone as a low-cost multi-channel optical fibre spectrophotometer suitable for physics laboratory classes. A custom-designed cradle and structure support were fabricated using 3D printing. The plastic optical fibres were arranged and inserted into the hole of the cradle to guide the light to the rear camera...

The aim of this study was to investigate the effect of surface modification of a polycaprolactone scaffold on promoting osteogenic differentiation of stem cells from human exfoliated deciduous teeth. Four different polycaprolactone scaffold were evaluated: untreated; coated with hyaluronic acid; coated with gelatin; and coated with hyaluronic acid...

COVID-19, caused by infection with SARS-CoV-2, has emerged and been rapidly spreading. The disease has now reached the level of a global pandemic and as a result a more rapid and simple detection method is imperative to curb the spreading of the virus. We aimed to develop a visual diagnostic platform of SARS-CoV-2 based on colorimetric RT-LAMP with...

PurposeThis study evaluated calculus removal efficacy of household vinegar and its effect on autopolymerizing orthodontic resin following repeated immersion.MethodsA total of 72 sectioned specimens of orthodontic retainers with calculus deposits following cleaning with the help of immersion in vinegar of different dilutions between 12.5% and 100%,...

In this research studied on the conjugation of antibodies on gold nanoparticles (GNPs) and the optimization in term of antibody concentration and albumin blocking concentration. Gold nanoparticleswith diameter size of ~20 nm were synthesized via chemical reduction of HAuCl4 with trisodium citrate as reducing and stabilizing agent. Gold nanoparticle...

The optical fiber deposits with gold nanorods was successfully accomplished as a biosensor device which sensing to the refractive index change on the surrounding surface. The principle is based on the localized surface plasmon resonance (LSPR) occurs on the metal surface of gold nanorods (AuNRs). The gold nanorods were coated on the glass core fibe...

Biochips for multiplex blood typing through surface plasmon resonance imaging (SPRi) readout have been previously reported based on arrays of red blood cell (RBC) specific ABO antibodies (Abs). Although conventional surfaces, such as CM-dextran, are robust and highly specific, they are time and labor intensive to generate and functionalize. This wo...

Quasi‐2D perovskites strike a good balance between high performance and stability for solar cell applications. Formamidinium iodide doping could improve thermal stability and broaden optical absorption, yet tends to cause poor morphology. The work featured on this cover presents a new strategy to optimize the morphology, electronic properties, and...

Perovskite materials show excellent photovoltaic performance along with simple processing and low‐energy requirement. Even with high power conversion efficiency (PCE), instability to moisture is still a major challenge. An effective method to enhance perovskite stability is by reducing dimensionality through incorporation of long organic cations in...

In this work, we report the in situ growth of gold nanoparticles (AuNPs) for the improvement of a transmission surface plasmon resonance (T-SPR) sensor to detect human immunoglobulin G (IgG). Human IgG was immobilized on an activated self-assembled monolayer of 11-mercaptoundecanoic on a gold-coated grating substrate. The T-SPR system was also used...

Polymethyl methacrylate (PMMA) based point of care (POC) for ABO-Rh(D) blood grouping by the naked eye was investigated. PMMA substrate was covalently linked with carboxyl methyl dextran (CMD) and coupled to the blood group specific antibodies anti A, anti B, and anti D, which were patterned into “A”, “B”, and “+”. The red read out color originated...

Perovskites have attracted considerable attention for application as high-efficiency photovoltaic devices owing to their low-cost and low-temperature fabrication. A good surface and high crystallinity are necessary for high-performance devices. We examine the negative effects of chemical ambiences on the perovskite crystal formation and morphology....

The main objective of this study was to prepare bead milled-silica nanoparticles (SiO2) as reinforcing materials for transparent hard coating films. SiO2 dispersed in Dowanol PM without any stabilizer was used as a main component in the nanocomposite hard coating films to improve hardness of Poly methyl methacrylate (PMMA) sheets. However, the majo...

The application of Surface Plasmon Resonance Imaging (SPRi) for the detection of transmembrane antigen of the Rhesus (Rh) blood group system is demonstrated. Clinically significant Rh blood group system antigens, including D, C, E, c, and e, can be simultaneously identified via solid phase immobilization assay, which offers significant time savings...

This aim of the study was to investigate the cytotoxicity of two commercial and two experimental dental flosses. Two commercial, Oral B® Essential Floss (nylon-waxed) and Thai Silk Floss (silk-waxed), and two experimental, Floss X (nylon-waxed) and Floss Xu (nylon-unwaxed) dental flosses were used. The cytotoxic assay was performed by using cell cu...

Objective: To investigate the effect of a cross-linking agent on the mechanical properties of self-cured orthodontic acrylic resin using PMMA powder (CPM-PMMA) with a compromised microstructure. Materials and methods: The mechanical properties of three sample groups were investigated in this study: CPM-PMMA, orthocryl and orthoplast. CPM-PMMA po...

The development of hard coating based on colloidal silica nanoparticles on polymethyl methacrylate (PMMA) sheet was reported. The colloidal silica was surface-modified with methyltrimethoxysilane (MTMS) and formulated to hard coating solution via sol-gel process. The hard coating solution was applied to PMMA surface by spray deposition technique. S...

Low antigenic expression of ABO subgroup system on red blood cell (RBC) is cause of discrepancy between forward and reverse blood typing in the standard agglutination technique. Neutralization agglutination is employed for verification of the detection of ABH substances in saliva. However, the neutralization technique is complicated, time-consuming...

This work developed a method to reuse the gold (Au) sensor chip for surface plasmon resonance (SPR) spectroscopy. The SPR chip, used in blood group typing, was regenerated to remove a functional layer and/or biomolecular layer by UV ozone technique. The layer on the used SPR surface consisted of a functional layer of carboxymethyldextran (CMD) and...

To compare maximum load, percentage of elongation, physical characteristics of 4 types of dental floss: (1) Thai Silk Floss (silk, waxed), (2) Oral B® Essential Floss (nylon, waxed), (3) Experimental Floss Xu (nylon, unwaxed), (4) Experimental Floss Xw (nylon, waxed). Four types of floss were tested (n=30) with a Universal Testing Machine (Instron®...

Recently, gold nanorods (AuNRs) have been developed and widely used in chemical and biological analysis because of its physical and chemical properties. The gene of antimicrobial resistance, Vancomycin-resistant enterococci (VRE), was studied by tagging to AuNRs. The aim of this work is to develop new diagnostic DNA techniques to be shorter time de...

Composite resin blocks for computer-aided design/computer-aided manufacturing (CAD/CAM) applications have recently become available. However, CAD/CAM composite resins have lower wear resistance and accumulate more plaque than CAD/CAM ceramic materials. We assessed the effects of SiO2-nanocomposite film coating of four types of CAD/CAM composite res...

Epoxy adhesive has been widely used in microelectronic production process and the technique to determine the degree of tiny dot adhesive cure is essential to evaluate the products. In this work, micro Raman spectra were demonstrated to examine the adhesive curing at small diameter of about hundred micrometers. There are two Raman peaks that can be...

The optical and mechanical properties of single layer nanocomposite films, with refractive indices (n) matched for an allyl diglycol carbonate (CR-39) substrate, with n = 1.50, were investigated. Alumina nanoparticles (ALO NPs 20 nm) and zirconia nanoparticles (ZrAc NPs 50 nm) in colloidal form were incorporated in the nanocomposites to improve fil...

Background: Miltenberger (Mi) series are the collective glycophorin hybrids in the MNS blood group system. Mi series are composed of several subtypes, for examples, GP.Mur, GP.Hop, and GP.Bun. The incompatibility of Mi series blood transfusion poses the risk of hemolysis. Due to the lack of standard antibodies for Mi series blood typing, colorimet...

The main objective of this work was to study the formation of abrasion resistance nanocomposite coating for teak wood that was fabricated from silicon dioxide nanoparticles (SNPs) and methyltrimethoxysilane (MTMS) via a sol–gel process. SNPs were used to enhance the abrasion resistance property, while MTMS acted as a matrix and rendered the flexibi...

This study reports loop-mediated isothermal amplification (LAMP) for rapid detection of methicillin-resistant Staphylococcus aureus from direct clinical specimens. Four primers including outer and inner primers were specifically designed on the two target sequences-femB to identify S. aureus and mecA to identify antibiotic-resistant gene. Reference...

In this study, surface plasmon resonance imaging (SPR imaging) was developed for the detection of Candida albicans which is a causal agent of oral infection. The detection was based on the sandwich assay. The capture antibody was covalently immobilized on the mixed self assemble monolayers (SAMs). The ratio of mixed SAMs between 11-mercaptoundecano...

In this study, protein microarrays based on sandwich immunoassays are generated to quantify the amount of alpha fetoprotein (AFP) in blood serum. For chip generation a mixture of capture antibody and a photoactive copolymer consisting of N,N-dimethylacrylamide (DMAA), methacryloyloxy benzophenone (MaBP), and Na-4-styrenesulfonate (SSNa) was spotted...

This work presents a novel method to reuse the gold (Au) sensor chip for surface plasmon resonance (SPR) spectroscopy. The SPR chip, used in ABO blood group typing, was regenerated with a functional layer and biomolecule layer on the SPR surface by UV/ozone method. The layer of used SPR consisted of a functional layer of carboxyl methylate dextran...

In this study, we demonstrate a long-range surface plasmon resonance (LR-SPR) biosensor for the detection of whole cell by captured antigens A and B on the surface of red blood cells (RBCs) as a model. The LR-SPR sensor chip consists of high-refractive index glass, a Cytop film layer, and a thin gold (Au) film, which makes the evanescent field inte...

Objectives: To develop reliable and convenient methods for Miltenberger (Mi(a) ) blood group typing. Aim: To apply real-time polymerase chain reaction (qPCR) melting curve analysis to Mi(a) blood group typing. Background: The Mi(a) blood group is the collective set of glycophorin hybrids in the MNS blood group system. Mi(a+) blood is common am...

In this study, we evaluated surface plasmon resonance imaging (SPR imaging) as a DNA biosensor for the detection of methicillin-resistant Staphylococcus aureus (MRSA) which is one of the most common causes of nosocomial infections. The DNA sample were collected from clinical specimens, including sputum and blood hemoculture were undergone LAMP ampl...

Signal enhancement based surface plasmon resonance imaging (SPR imaging) was developed using gold nanoparticle (AuNP) for detection of Acidovorax avenae subsp. citrulli (Aac). The antibodies against Aac, monoclonal antibody 11E5 (MAb 11E5) and polyclonal antibody MPC (PAb MPC), were covalently immobilized on the 1:40 of mixed self-assembled monolay...

Hepatocellular carcinoma is a one of the most common cancer in the world and the third cause of cancer-related death. The recommended screening test for patients are the detection of serum α-fetoprotein (AFP) levels and an abdominal ultrasound every 6 months to detect HCC. To inform stage of the diasease, we investigate the alpha fetoprotein (AFP)...

Aim of this work is to develop a surface plasmon resonance (SPR) technique for detection of anti-A and anti-B which are the antibodies specific to ABO blood group in serum based on solid phase immobilization of antigens on the surface. Synthetic antigens A and B were immobilized on the carboxymethyldextran (CMD) surface to measure the antibodies. T...

Solid phase microarrays have been described for use in blood typing; red blood cells (RBCs) captured on immobilized antibodies were detected using surface plasmon resonance or fluorescence. We present antibody microarray on Poly (methylmethacrylate) (PMMA) surface coupled with microfluidic system for ABO and RhD blood typing. After immobilized by a...

The phase shift on reflection from the colloidal photonic crystal film was measured by the Fabry-Pérot resonant cavity along the cross-section of the photonic crystal film without additional optical parts. The wet colloidal photonic crystal film was fabricated by dip-coating an agarose-gel-coated glass substrate into a suspension containing monodis...

Wear resistance is a limitation of artificial denture teeth. Improving the wear resistance of conventional artificial denture teeth is of value to prosthodontic patients. The purpose of this in vitro study was to evaluate the wear resistance and hardness of modified polymethyl methacrylate artificial denture teeth compared to 5 commercially availab...

The magnetic nanoparticles of cobalt-and nickel-iron oxide have been extensive interest due to their superparamagnetic properties and their potential applications in many fields. The iron, cobalt and nickel can stay in many oxidation states and are easily oxidized especially in ambient air therefore the composition and oxidation states of these oxi...

A flow-induced cell movement assay combined with a surface plasmon resonance (SPR) technique was developed to quantify the agglutination strength, derived from the standard tube agglutination test. Red blood cells (RBCs), based on the ABO blood group system, were specifically captured by anti-A and/or anti-B antibodies immobilized on a sensor surfa...

Poly (vinyl alcohol)-silver nanoparticles (PVA:AgNPs), and poly (vinyl alcohol)-silver nanoparticles-poly (3, 4-ethylene dioxythiophene)/poly (styrene sulfonate) (PVA:AgNPs: PEDOT/ PSS) were generated as ultra-fine electrospun fibers using the aligned fiber mat and aligned single fiber techniques. SEM and TEM were used to confirm the morphology, di...

This research project produced two fabricated ultrafine conductive polymeric fibers. The first fiber was fabricated from a polymer and conductive polymer solution, and the second was fabricated from a polymer and metal nanoparticle/ nanocomposite. The resulting fibers were characterized and analyzed. For all fiber samples, the ultrafine polymeric f...

Statement of problem: Polysiloxane has been used as a coupling material in restorative dental materials for several decades. However, few studies are available on the application of polysiloxane in other dental prosthesis functions. Purpose: The purpose of this study was to investigate the effects of silane-SiO2 nanocomposite films on Candida al...

The aim was to investigate particles of poly (methylmethacrylate)(PMMA) prepared by suspension polymerization using different concentration of a stabilizer and by varying of the agitation speed at 300, 400, and 500 rpm. Particle size distribution (PSD), and morphology of the PMMA powders were observed and compared with commercial orthodontic PMMA p...

Objective: To evaluate the effects of interchanging the liquid components of two commercially available orthodontic auto-polymerizing acrylic resin in their flexural properties, clarity and setting time

The DNA hybridization of methicillin-resistant staphylococcus aureus (MRSA) was investigated by using surface plasmon resonance (SPR). 3 dimensional (3D) surface, carboxymethyl dextran hydrogel, were used as the sensor surface. The surface was functionalized with streptavidin where the biotinylated DNA probe can be specifically bound. Loop-mediated...

The important parameter for the application in biomedical sensor is specificity on the specimen. However, there is the limitation in a low detection signal in real sample applications. The measurement cannot avoid contaminant from some biomolecules, components in patient samples such as blood or serum, which are effect on low detection or error dia...

A quartz crystal microbalance (QCM) technique was used to reveal the effect of alkanethiol self-assembled monolayers (SAMs) on the viscoelastic property and cell adhesion process of cultured fibroblasts (L929), by measuring the change in frequency (∆f) and resistance (∆R). Four types of SAMs having different functional groups including hydroxyl (OH...

In this work particular attention has been paid to the aging behavior of biaxially oriented polypropylene (BOPP) film surfaces modified with the acrylic acid (AAc) corona discharge treatment previously reported. Three different corona energies of 15.3, 38.2 and 76.4 kJ/m(2) were studied. The surface properties of treated films during 90 days of agi...

In this study, readily available antibodies that are used in standard agglutination tests were evaluated for their use in ABO blood typing by a surface plasmon resonance imaging (SPR imaging) technique. Five groups of antibodies, including mixed clones of anti-A, anti-B, and anti-AB, and single clones of anti-A and anti-B, were used to construct th...

Self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA) were applied on tin-doped indium oxide (ITO) surfaces and used as a working electrode for sensing DNA hybridization. The concentration of probe single stranded DNA (ssDNA), complemented with target DNA, was optimized for the highest yield immobilization on MPA/ITO platform. The ssDNA...

A polymer substrate based surface plasmon resonance (SPR) technique was developed for detection of specific monoclonal antibody 10B2 (MAb 10B2) against bacterium Acidovorax avenae subsp. citrulli (Aac). The monolayer of Aac antigen was physically immobilized on 95:5 polystryrene – copoly acrylic acid (95PSMA) for detection of antibody. The amount o...

Teak wood is widely used for the housing interior and decoration because of its beautiful grains appearance; however, it often suffers from surface damage especially in the tiling application. The remedy is to apply a protective layer such as polyurethane (PU). In this work, the sol-gel inorganic reinforced hard coating formulation based on silicon...

Objective: The aim of this in vitro study was to compare the flexural strength and flexural modulus of three formulae self-curing acrylic resin with commercial orthodontic resin.

The binary toxin produced by Lysinibacillus sphaericus is composed of BinA and BinB subunits that work together in governing toxicity against mosquito larvae. BinA is proposed to be important for toxicity, whereas BinB has been shown to act as a specific receptor-binding component. The precise function of both subunits, however, is not well establi...

In this dissertation, we studied the mechanical behaviors of HDPE fiber reinforced in cement mortar. One of our major concerns is to study the utilization of high strength high density polyethylene (HDPE) fibers obtained from different draw ratio melt spinning processing. Another major concern is to compare these fibers in term of mechanical behavi...

To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. The antimicr...

Trends in disposable and handheld biosensors have called for miniaturized and planar electrodes in the place of conventional bulky ones. In this work, thin tin-doped indium oxide (ITO) film coated on glass were used as a based electrode in a three-electrode electrochemical system to follow some biochemical activities, such as NADH and phenol activi...

The formation of scratch-resistant coating film prepared from colloidal silica and a polysiloxane matrix was investigated. Methyltrimethoxysilane (MTMS) was hydrolysed and mixed with silica sol (SiO2) at various compositions to form the hybrid hard-coating nanocomposite film. The hydrolysed MTMS (polysiloxane) acts as the polymeric binder that is c...

Two types of superparamagnetic nanoparticles, namely magnetite (Fe 30 4) and iron-platinum (FePt), with their surface modified by oleic acid and oleyleamine were synthesized using the the polyol process and dispersed in n-hexane. Vibrating-sample magnetometry (VSM) was used to characterize the FePt and the magnetic susceptibility of the Fe 3O 4 was...

Silver zirconium phosphate (AgZrP) was incorporated into nylon 6,10 fibers by using a twin screw extruder to produce antimicrobial fibers. Monofilament fibers with various degrees of AgZrP loading were prepared by the melt‐spinning process. The surface concentration of AgZrP particles was found to be dependent on AgZrP loading. A poor interface bet...

The effect of surface polarity on the adsorption of bovine serum albumin (BSA) on polystyrene (PS), 7% polystyrene-co-maleic anhydride (7%PSMAn) and 50% polystyrene-co-maleic acid (50%PSMA), at pH 7.4, was investigated. Polystyrene represented the non-polar surface while 7%PSMAn and 50%PSMA represented a low and high acid content copolymer. The amo...

Objective: This study aimed to investigate fluoride release, flexural strength and surface characteristics of three orthodontic acrylic resins (A) blended with (1) sodium fluoride powder (NaF), (2) calcium fluoride powder (CaF2), and (3) glass ionomer cement powder (GIC). Material & Methods: Acrylic resin was blended with NaF, CaF2 , and GIC to mak...

Bacillus sphaericus produces mosquito-larvicidal binary toxin composed of BinA and BinB. While BinB is expected to bind to a specific receptor on the cell membrane, BinA interacts to BinB or BinB receptor complex and translocates into the cytosol to exert its activity via unknown mechanism. To investigate functional roles of aromatic cluster in Bin...

Surface plasmon resonance (SPR) sensors with spectral interrogation provide a high refractive index resolution, a large dynamic range and a fixed optical detection module. In this work, we propose a new multichannel spectral detection unit that uses only one spectrometer to measure the reflection spectrum from multiple sensing spots serially withou...

Ultra-fine PS/BEH-PF/EHO-OPPE fibers with average diameters ranging from 0.67 to 0.92 μm were successfully prepared by electrospinning a 8.5% (w/v) tertiary blend of PS/BEH-PF/EHO-OPPE (PS/BEH-PF/EHO-OPPE = 7.5:0.5:0.5 w/w/w) in chloroform (CF) with the addition of 8% (v/v) pyridinium formate (PF). Electrospun fibers from binary blends of PS/BEH-PF...

An immunosensor based on surface plasmon resonance imaging (SPR imaging) using a specific monoclonal antibody 11E5 (MAb 11E5) was developed for the detection of the seed-borne bacterium Acidovorax avenae subsp. citrulli (Aac), which causes fruit blotch in watermelons and cantaloupes, and compared to the conventional ELISA technique. The 1:40 mixed...

UV/vis absorption and photoluminescence (PL) spectroscopy were used to examine the photophysical properties of statistical copolymers, poly(9,9-di(2-ethylhexyl)fluorene-stat-anthracene), with the mole ratio of the anthracene group ranging from 0 to 20%. The incorporation of the anthracene group into the conjugated backbone of the polyfluorene affec...

Surface plasmon resonance (SPR) sensors with spectral interrogation provide a high refractive index resolution, a large dynamic range and a fixed optical detection module. In this work, we propose a new spectral detection unit that uses only one spectrometer to measure the SPR spectrum from multiple sensing spots rapidly and serially without any me...

The adsorption of tallow alkylammonium salts onto bentonite from the Lopburi province in Thailand, and the effect of surface wettability on the formation of polymer–clay nanocomposites are reported. We looked specifically at octadecyltrimethyl ammonium chloride (S18), a popular member of the tallow alkylammonium salt family. The adsorption of S18 o...

This study utilizes atomic force microscopy to investigate the self-assembling behaviors from dilute solution into thin film of a well-known conjugated polymer, poly(9,9-di(2-ethylhexyl)fluorene) (PF2/6). We have found that the structures of nanoscale aggregates depend on various experimental parameters including concentration, substrate and solven...

This article explores photophysical properties and aggregation behaviors of conjugated polymer, poly[2-methoxy, 5-(2′-ethylhexyloxy)-1,4-phenylenevinylene](MEH−PPV), in various solvent–nonsolvent systems by utilizing UV/vis absorption and photoluminescence (PL) spectroscopy. The isolated chains of MEH-PPV dispersed in solvents including dichloromet...

A recombinant polyester-degrading hydrolase from Thermobifida sp. BCC23166 targeting on aliphatic-aromatic copolyester (rTfH) was produced in Streptomyces rimosus R7. rTfH was expressed by induction with thiostrepton as a C-terminal His(6) fusion from the native gene sequence under the control of tipA promoter and purified from the culture supernat...

The effect of lignosulfonate as admixture on geopolymer paste compared to normal cement paste were investigated to understand I) the sensitivity of the performance of lignosulfonate to geopolymer, II) the effect of incresing amount of lignosulfonate on mechanical properties, III) the effect of inceresing amount of lignosulfonate on setting time and...

The layer formation of bovine serum albumin (BSA) on a poly(styrene-co-maleic acid) (PSMA) surface was investigated by using quartz crystal microbalance (QCM) technique at various pH values. The formation of a BSA surface was examined by atomic force microscopy (AFM). To study the effect on the layer formation, the pH of solution was varied from 2...

Quartz crystal microbalance technique was used to study kinetic of formation and digestion of bovine serum albumin (BSA) protein on polystyrene-co-maleic acids (PSMA) surface. The kinetic of formation and digestion of BSA was investigated by measuring the frequency shift and resistance shift as a function of time. In order to study pH and concentra...

Biosensor structure comprising of Si3N4 micro-grating arrays coated with spin-on-glass material was investigated. This grating structure was located on the silicon groove, which etched by deep reactive ion etching process. The grating surface was attached by immobilized 23 oligonucleotides as a probe, and hybridized with a complementary target. The...

This contribution investigates photophysical change of poly(9,9-di(2-ethylhexyl)fluorene) (PF2/6) and its random copolymer with anthracene in solvent–non-solvent system. Isolated chains of the polymers in good solvent are driven to associate by addition of a poor solvent. The increase of interchain interactions upon decreasing solvent quality is fo...

An investigation into the surface plasmon resonance (SPR) sensor surface for the detection of enzyme reaction is reported. The thin polymeric film is prepared by spin casting poly (styrene-co-maleic acid) [PSMA] on a chromium/gold-coated SPR substrate. Bovine serum albumin (BSA) is adsorbed onto this surface with a mix of side-on and end-on orienta...

In this contribution, we report a versatile method for tuning optical prop- erties of poly(2-methoxy-5-(20-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) in its solution with 1,2-dichloroethane, accomplished by reacting with pyridinium for- mate (PF), a volatile organic salt. We can systematically control the positions of absorption and photolumin...

A polyhydroxyalkanote depolymerase gene from Thermobifida sp. isolate BCC23166 was cloned and expressed as a C-terminal His6-tagged fusion in Pichia pastoris. Primary structure analysis revealed that the enzyme PhaZ-Th is a member of a proposed new subgroup of SCL-PHA depolymerase containing a proline–serine repeat linker. PhaZ-Th was expressed as...

The surface of polystyrene (PS) thin films in argon plasma was modified to study the hydrophilicity properties. An inductively coupled plasma (ICP) system was used to generate the argon plasma. In the experiment, the effect of RF power levels, gas flow rate and treatment time was investigated. The surface morphology of PS films was examined by the...

The photo-induced response of an ultra thin polymeric film of poly 4′-(6-acryloxy) hexyloxy-4-methoxyazobenzene (P5) is investigated. A monolayer of P5 at a gas–water interface possesses a mean molecular area of 28.0Å2/monomer-repeat. Multilayer films of P5 were prepared by horizontal deposition at a surface pressure of 25mN/m2. The uniformity of t...

We introduce and experimentally demonstrate a fiber-connectorized optical system based on the use of a fiber-loop mirror (FLM) to study both the optical transmissivity and the optical phase retardation of a material. Our approach to investigating the optical transmissivity of a test sample is by initially adjusting the optical powers at both FLM ou...

The present contribution reports the electrospinning of PS/MEH‐PPV fibers with average diameters ranging from 0.165 to 1.190 µm from solutions of PS/MEH‐PPV (PS/MEH‐PPV = 7.5:1, w/w) in 1,2‐dichloroethane. With the addition of pyridinium formate (PF), a volatile organic salt, to the PS/MEH‐PPV solution, the electrospinnability of the resulting solu...

In this report, the role of local polymer–solvent π–π-interaction on rotational dynamics of phenyl rings of poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEH-PPV) is examined by utilizing nuclear magnetic resonance (NMR) spectroscopy. We have found that an aromatic solvent can couple strongly with the phenyl rings via favorable local...

UV/vis absorption, excitation, and emission spectroscopies are utilized to explore the association behavior of conjugated polymer, poly[2-methoxy, 5-(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV), in a homologous series of linear alcohols and solvent–nonsolvent systems. We demonstrate that the aggregation, agglomeration, and collapse of isolated...

A relationship between conformation and photophysics of poly[2-methoxy-5-(2‘-ethylhexoxy)-p-phenylenevinylene] (MEH−PPV) in dilute solution was investigated by utilizing UV/vis absorption, excitation, and emission spectroscopy. By tuning polymer−solvent interactions, a control of conjugation length which relates to state of chain collapse is achiev...

Toxicity mechanisms of Bacillus thuringiensis Cry insecticidal proteins involve membrane insertion and lytic pore formation in lipid bilayers of the target larval midgut cell membranes. The B. thuringiensis Cry4Ba mosquito-larvicidal protein has been shown to be capable of permeabilizing liposome vesicles and of forming ion channels in planar lipid...

Geometries and energy gaps of poly(para-phenylenevinylene) oligomers (OPVN) and their alkoxy derivatives were investigated, based on quantum-chemical calculations. This oligomer series includes poly(para-methoxy-PV) (DMO-OPVN), poly(para-hexoxy-PV) (DHO-OPVN) and poly(2-methoxy,5-(2′-ethyl-hexyloxy)-PV) (MEH-OPVN). Potential energy hypersurfaces of...

The melt intercalation of polystyrene (PS) into organoclay with variation in the degree of surfactant coverage by melt intercalation was investigated. The surface coverage of the organoclay was found to play a major role in controlling the type of the final composites formation. Two major types of composites were found depending upon the surface tr...

Ultrafine polystyrene (PS)/poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) fibers were successfully prepared by electrospinning of PS/MEH-PPV solutions in chloroform, 1,2-dichloroethane, and tetrahydrofuran (THF). Three concentrations of the solutions were prepared: 8.5, 16, and 23.5% (w/v), with the compositional weight ratio...

An effect of the cation-exchange capacity (CEC) on the formation of polystyrene-clay nanocomposites is reported. Two types of 2:1 layered silicates with different CECs, Wyoming (97 mequiv/100 g of clay) and bentonite H (BNH; 131 mequiv/100 g of clay) were investigated. The organoclay was prepared through the mixing of purified clay and octadecyldim...