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The efficacy of silastic sheet nasal splints in endoscopic nasal septal repair surgery: a prospective, randomized, single-blinded controlled trial

Alasousi F, Fan J, Pascual A, Hernaiz-Leonardo JC, Javer AR

Int Forum Allergy Rhinol, 2021 09;11(9):1381-1383.
PMID: 33742768 DOI: 10.1002/alr.22791
Matched MeSH terms: Dimethylpolysiloxanes*
Fulltext Latex micro-balloon pumping in centrifugal microfluidic platforms

Aeinehvand MM, Ibrahim F, Harun SW, Al-Faqheri W, Thio TH, Kazemzadeh A, et al.

Lab Chip, 2014 Mar 07;14(5):988-97.
PMID: 24441792 DOI: 10.1039/c3lc51116b

Centrifugal microfluidic platforms have emerged as point-of-care diagnostic tools. However, the unidirectional nature of the centrifugal force limits the available space for multi-step processes on a single microfluidic disc. To overcome this limitation, a passive pneumatic pumping method actuated at high rotational speeds has been previously proposed to pump liquid against the centrifugal force. In this paper, a novel micro-balloon pumping method that relies on elastic energy stored in a latex membrane is introduced. It operates at low rotational speeds and pumps a larger volume of liquid towards the centre of the disc. Two different micro-balloon pumping mechanisms have been designed to study the pump performance at a range of rotational frequencies from 0 to 1500 rpm. The behaviour of the micro-balloon pump on the centrifugal microfluidic platforms has been theoretically analysed and compared with the experimental data. The experimental data show that the developed pumping method dramatically decreases the required rotational speed to pump liquid compared to the previously developed pneumatic pumping methods. It also shows that within a range of rotational speed, a desirable volume of liquid can be stored and pumped by adjusting the size of the micro-balloon.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry
Fulltext Preliminary characterization study based on cyclic voltammetry and reliability of a fabricated Au/Ti microfluidic three-electrode sensor

Hamzah, I.H., Sidek, O., Abd Manaf, A.

ASM Science Journal, 2010;4(2):142-148.
MyJurnal

A preliminary study was carried out to fabricate a three electrode system based on electrochemical sensoring. The cyclic voltammetry (CV) technique was chosen to select the type of metal suitable for evaporation and to compare the results produced from the fabricated gold electrode with the conventional macro-electrode system. The methodology and apparatus used involved low cost apparatus and methodology such as soft lithography, wet-etching, thermal evaporation, direct current sputtering, polymethylmethacrylate moulding and polydimethylsiloxane coating. The experiment was conducted at a fixed scan rate of 100 mV/s by using 0.01 M K3Fe(CN)6 in 0.1M KCl and well known method using Randles-Sevcik equation, peak current ratio and voltage separation was used to analyze the characterization on the fabricated sensors. Electrodes of 6.5 mm2 and 0.26 mm2 were fabricated to prove the adsorption effect of the reactant and the influence of the electrode area on the value of the peak current. CV analysis proved that the fabricated sensor was reliable for a range of 24 h at 25ºC room temperature.

Matched MeSH terms: Dimethylpolysiloxanes
Solid phase microextraction using new sol-gel hybrid polydimethylsiloxane-2-hydroxymethyl-18-crown-6-coated fiber for determination of organophosphorous pesticides

Wan Ibrahim WA, Farhani H, Sanagi MM, Aboul-Enein HY

J Chromatogr A, 2010 Jul 23;1217(30):4890-7.
PMID: 20561627 DOI: 10.1016/j.chroma.2010.05.050

A new sol-gel hybrid coating, polydimethylsiloxane-2-hydroxymethyl-18-crown-6 (PDMS-2OHMe18C6) was prepared in-house for use in solid phase microextraction (SPME). The three compositions produced were assessed for its extraction efficiency towards three selected organophosphorus pesticides (OPPs) based on peak area extracted obtained from gas chromatography with electron capture detection. All three compositions showed superior extraction efficiencies compared to commercial 100 microm PDMS fiber. The composition showing best extraction performance was used to obtain optimized SPME conditions: 75 degrees C extraction temperature, 10 min extraction time, 120 rpm stirring rate, desorption time 5 min, desorption temperature 250 degrees C and 1.5% (w/v) of NaCl salt addition. The method detection limits (S/N=3) of the OPPs with the new sol-gel hybrid material ranged from 4.5 to 4.8 ng g(-1), which is well below the maximum residue limit set by Codex Alimentarius Commission and European Commission. Percentage recovery of OPPs from strawberry, green apple and grape samples with the new hybrid sol-gel SPME material ranged from 65 to 125% with good precision of the method (%RSD) ranging from 0.3 to 7.4%.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry*
ANN modeling of the penetration across a polydimethylsiloxane membrane from theoretically derived molecular descriptors

Agatonovic-Kustrin S, Beresford R, Yusof AP

J Pharm Biomed Anal, 2001 Sep;26(2):241-54.
PMID: 11470201

A quantitative structure-permeability relationship was developed using Artificial Neural Network (ANN) modeling to study penetration across a polydimethylsiloxane membrane. A set of 254 compounds and their experimentally derived maximum steady state flux values used in this study was gathered from the literature. A total of 42 molecular descriptors were calculated for each compound. A genetic algorithm was used to select important molecular descriptors and supervised ANN was used to correlate selected descriptors with the experimentally derived maximum steady-state flux through the polydimethylsiloxane membrane (log J). Calculated molecular descriptors were used as the ANN's inputs and log J as the output. Developed model indicates that molecular shape and size, inter-molecular interactions, hydrogen-bonding capacity of drugs, and conformational stability could be used to predict drug absorption through skin. A 12-descriptor nonlinear computational neural network model has been developed for the estimation of log J values for a data set of 254 drugs. Described model does not require experimental parameters and could potentially provide useful prediction of membrane penetration of new drugs and reduce the need for actual compound synthesis and flux measurements.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry*
Microfluidic formation of highly monodispersed multiple cored droplets using needle-based system in parallel mode

Lian Z, Chan Y, Luo Y, Yang X, Koh KS, Wang J, et al.

Electrophoresis, 2020 06;41(10-11):891-901.
PMID: 31998972 DOI: 10.1002/elps.201900403

Scale-up in droplet microfluidics achieved by increasing the number of devices running in parallel or increasing the droplet makers in the same device can compromise the narrow droplet-size distribution, or requires high fabrication cost, when glass- or polymer-based microdevices are used. This paper reports a novel way using parallelization of needle-based microfluidic systems to form highly monodispersed droplets with enhanced production rates yet in cost-effective way, even when forming higher order emulsions with complex inner structure. Parallelization of multiple needle-based devices could be realized by applying commercially available two-way connecters and 3D-printed four-way connectors. The production rates of droplets could be enhanced around fourfold (over 660 droplets/min) to eightfold (over 1300 droplets/min) by two-way connecters and four-way connectors, respectively, for the production of the same kind of droplets than a single droplet maker (160 droplets/min). Additionally, parallelization of four-needle sets with each needle specification ranging from 34G to 20G allows for simultaneous generation of four groups of PDMS microdroplets with each group having distinct size yet high monodispersity (CV < 3%). Up to six cores can be encapsulated in double emulsion using two parallelly connected devices via tuning the capillary number of middle phase in a range of 1.31 × 10-4 to 4.64 × 10-4 . This study leads to enhanced production yields of droplets and enables the formation of groups of droplets simultaneously to meet extensive needs of biomedical and environmental applications, such as microcapsules with variable dosages for drug delivery or drug screening, or microcapsules with wide range of absorbent loadings for water treatment.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry
Wirelessly activated device with an integrated ionic polymer metal composite (IPMC) cantilever valve for targeted drug delivery

Cheong HR, Nguyen NT, Khaw MK, Teoh BY, Chee PS

Lab Chip, 2018 10 09;18(20):3207-3215.
PMID: 30229248 DOI: 10.1039/c8lc00776d

This paper reports a wirelessly powered ionic polymer-metal composite (IPMC) soft actuator operated by external radio frequency (RF) magnetic fields for targeted drug delivery. A 183 μm thick IPMC cantilever valve was fitted with an embedded LC resonant circuit to wirelessly control the actuator when the field frequency is tuned to its resonant frequency of approximately 25 MHz. Experimental characterization of the fabricated actuator showed a cumulative cantilever deflection of 160 μm for three repeated RF ON-OFF cycles at 0.6 W input power. The device was loaded with a dye solution and immersed in DI water to demonstrate wireless drug release. The qualitative result shows the successful release of the dye solution from the device reservoir. The release rate can be controlled by tuning the RF input power. We achieved a maximum average release rate of ∼0.1 μl s-1. We further conducted an in vitro study with human tumor cells (HeLa) to demonstrate the proof of concept of the developed device. The experiments show promising results towards the intended drug delivery application.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry*
Nanoscaled Surface Modification of Poly(dimethylsiloxane) Using Carbon Nanotubes for Enhanced Oil and Organic Solvent Absorption

Ong CC, Sundera Murthe S, Mohamed NM, Perumal V, Mohamed Saheed MS

ACS Omega, 2018 Nov 30;3(11):15907-15915.
PMID: 31458235 DOI: 10.1021/acsomega.8b01566

This article demonstrates a novel nanoscale surface modification method to enhance the selectivity of porous poly(dimethylsiloxane) (PDMS) in removing oil from water. The surface modification method is simple and low cost by using sugar as a sacrificial template for temporal adhering of carbon nanotubes (CNT) before addition of PDMS prepolymer to encapsulate the CNT on its surface once polymerized. The PDMS-CNT demonstrated a tremendous increase in absorption capacity up to 3-fold compared to previously reported absorbents composed solely of PDMS. Besides showcasing excellent absorption capacity, the PDMS-CNT also shows a faster absorption rate (25 s) as compared to that of pure PDMS (40 s). The enhanced absorption rate is due to the incorporation of CNT, which roughens the surface of the polymer at the nanoscale and lowers the surface energy of porous PDMS while at the same time increasing the absorbent hydrophobicity and oleophilicity. This property makes the absorbent unique in absorbing only oil but repelling water at the same time. The PDMS-CNT is an excellent absorbent material with outstanding recyclability and selectivity for removing oil from water.

Matched MeSH terms: Dimethylpolysiloxanes
Fulltext Preparation, Characterization, and Performance Evaluation of Polysulfone Hollow Fiber Membrane with PEBAX or PDMS Coating for Oxygen Enhancement Process

Chong KC, Lai SO, Lau WJ, Thiam HS, Ismail AF, Roslan RA

Polymers (Basel), 2018 Jan 28;10(2).
PMID: 30966162 DOI: 10.3390/polym10020126

Air pollution is a widely discussed topic amongst the academic and industrial spheres as it can bring adverse effects to human health and economic loss. As humans spend most of their time at the office and at home, good indoor air quality with enriched oxygen concentration is particularly important. In this study, polysulfone (PSF) hollow fiber membranes fabricated by dry-jet wet phase inversion method were coated by a layer of polydimethylsiloxane (PDMS) or poly(ether block amide) (PEBAX) at different concentrations and used to evaluate their performance in gas separation for oxygen enrichment. The surface-coated membranes were characterized using SEM and EDX to determine the coating layer thickness and surface chemical properties, respectively. Results from the gas permeation study revealed that the PSF membrane coated with PDMS offered higher permeance and selectivity compared to the membrane coated with PEBAX. The best performing PDMS-coated membrane demonstrated oxygen and nitrogen gas permeance of 18.31 and 4.01 GPU, respectively with oxygen/nitrogen selectivity of 4.56. Meanwhile, the PEBAX-coated membrane only showed 12.23 and 3.11 GPU for oxygen and nitrogen gas, respectively with a selectivity of 3.94. It can be concluded the PDMS coating is more promising for PSF hollow fiber membrane compared to the PEBAX coating for the oxygen enrichment process.

Matched MeSH terms: Dimethylpolysiloxanes
Fulltext Molecular Dynamics Study of Poly(dimethylsiloxane) Nanostructure Distortion in a Soft Lithography Demolding Process

Abdul Manap AH, Md Izah SS, Mohamed K

ACS Omega, 2019 Dec 03;4(23):20257-20264.
PMID: 31815228 DOI: 10.1021/acsomega.9b02547

This study aims at investigating the distortion of poly(dimethylsiloxane) (PDMS) nanostructures in a soft lithography demolding process using molecular dynamics simulation. Experimental results show that after peeling, PDMS nanopillars became 10-60% longer in height than the mold size. Molecular dynamics simulations have been employed to plot the stress-strain curve of the nanopillars when subjected to uniaxial stress. Three force fields (COMPASS, CVFF, and PCFF) were used for modeling. The demolding process in soft lithography and nanoimprint lithography causes significant deformation in replication. The experimental results show clear signs of elongation after demolding. Molecular dynamics simulations are employed to study the stress-strain relationship of the PDMS nanopillars. The results from the simulation show that a PDMS nanopillar at temperature T = 300 K under tensile stress shows characteristics of flexible plastic under tensile stress and has a lower Young's modulus, ultimate tensile stress, and Poisson's ratio.

Matched MeSH terms: Dimethylpolysiloxanes
On-Demand Guided Bone Regeneration with Microbial Protection of Ornamented SPU Scaffold with Bismuth-Doped Single Crystalline Hydroxyapatite: Augmentation and Cartilage Formation

Selvakumar M, Srivastava P, Pawar HS, Francis NK, Das B, Sathishkumar G, et al.

ACS Appl Mater Interfaces, 2016 Feb 17;8(6):4086-100.
PMID: 26799576 DOI: 10.1021/acsami.5b11723

Guided bone regeneration (GBR) scaffolds are futile in many clinical applications due to infection problems. In this work, we fabricated GBR with an anti-infective scaffold by ornamenting 2D single crystalline bismuth-doped nanohydroxyapatite (Bi-nHA) rods onto segmented polyurethane (SPU). Bi-nHA with high aspect ratio was prepared without any templates. Subsequently, it was introduced into an unprecedented synthesized SPU matrix based on dual soft segments (PCL-b-PDMS) of poly(ε-caprolactone) (PCL) and poly(dimethylsiloxane) (PDMS), by an in situ technique followed by electrospinning to fabricate scaffolds. For comparison, undoped pristine nHA rods were also ornamented into it. The enzymatic ring-opening polymerization technique was adapted to synthesize soft segments of PCL-b-PDMS copolymers of SPU. Structure elucidation of the synthesized polymers is done by nuclear magnetic resonance spectroscopy. Sparingly, Bi-nHA ornamented scaffolds exhibit tremendous improvement (155%) in the mechanical properties with excellent antimicrobial activity against various human pathogens. After confirmation of high osteoconductivity, improved biodegradation, and excellent biocompatibility against osteoblast cells (in vitro), the scaffolds were implanted in rabbits by subcutaneous and intraosseous (tibial) sites. Various histological sections reveal the signatures of early cartilage formation, endochondral ossification, and rapid bone healing at 4 weeks of the critical defects filled with ornamented scaffold compared to SPU scaffold. This implies osteogenic potential and ability to provide an adequate biomimetic microenvironment for mineralization for GBR of the scaffolds. Organ toxicity studies further confirm that no tissue architecture abnormalities were observed in hepatic, cardiac, and renal tissue sections. This finding manifests the feasibility of fabricating a mechanically adequate nanofibrous SPU scaffold by a biomimetic strategy and the advantages of Bi-nHA ornamentation in promoting osteoblast phenotype progression with microbial protection (on-demand) for GBR applications.

Matched MeSH terms: Dimethylpolysiloxanes/pharmacology; Dimethylpolysiloxanes/chemistry
Fulltext Bending effects study on flexible wearable antenna for 2.45 GHz body centric wireless communications

Aslina A. Bakar, Amirul A. Mustafa, Ahmad R. Razali, Norhayati Mutalib, Amirudin Ibrahim

ESTEEM Academic Journal, 2020;16(2):75-87.
MyJurnal

This study aims to investigate the bending effects on the flexible wearable antenna by using copper nanowires and polydimethylsiloxane (PDMS). This project focuses on the bending effect on the proposed wearable antenna in the presence of skin tissue and at free space. The radiation characteristics were simulated and analyzed when the antenna was under flat and bent conditions. The performance result of return loss and radiation pattern (Efield and H-field) of proposed wearable antenna was analyzed. The material for the proposed antenna is designed to be flexible and wearable for the application of body-centric wireless communication (BCWCs) at the frequency of 2.45 GHz with the approval specifications of industrial, scientific and medical (ISM) band. Radiator for the proposed wearable antenna is fabricated using copper nanowire, and the antenna substrate is by using polydimethylsiloxane (PDMS). The performance result of the proposed wearable antenna was simulated by using CST microwave studio. From the simulated result for different bending angles, a conclusion was drawn that bending of structure can improve the impedance matching and return loss during the bent condition. However, the resonant frequency tends to shift as the antenna is bent up to 50°. At the critical angle of 70°, the frequency is shifted to a lower frequency.

Matched MeSH terms: Dimethylpolysiloxanes
Fabrication of multilayer-PDMS based microfluidic device for bio-particles concentration detection

Masrie M, Majlis BY, Yunas J

Biomed Mater Eng, 2014;24(6):1951-8.
PMID: 25226891 DOI: 10.3233/BME-141004

This paper discusses the process technology to fabricate multilayer-Polydimethylsiloxane (PDMS) based microfluidic device for bio-particles concentration detection in Lab-on-chip system. The micro chamber and the fluidic channel were fabricated using standard photolithography and soft lithography process. Conventional method by pouring PDMS on a silicon wafer and peeling after curing in soft lithography produces unspecific layer thickness. In this work, a multilayer-PDMS method is proposed to produce a layer with specific and fixed thickness micron size after bonding that act as an optimum light path length for optimum light detection. This multilayer with precise thickness is required since the microfluidic is integrated with optical transducer. Another significant advantage of this method is to provide excellent bonding between multilayer-PDMS layer and biocompatible microfluidic channel. The detail fabrication process were illustrated through scanning electron microscopy (SEM) and discussed in this work. The optical signal responses obtained from the multilayer-PDMS microfluidic channel with integrated optical transducer were compared with those obtained with the microfluidic channel from a conventional method. As a result, both optical signal responses did not show significant differences in terms of dispersion of light propagation for both media.

Matched MeSH terms: Dimethylpolysiloxanes/chemical synthesis*
Endothelial cell responses in terms of adhesion, proliferation, and morphology to stiffness of polydimethylsiloxane elastomer substrates

Ataollahi F, Pramanik S, Moradi A, Dalilottojari A, Pingguan-Murphy B, Wan Abas WA, et al.

J Biomed Mater Res A, 2015 Jul;103(7):2203-13.
PMID: 24733741 DOI: 10.1002/jbm.a.35186

Extracellular environments can regulate cell behavior because cells can actively sense their mechanical environments. This study evaluated the adhesion, proliferation and morphology of endothelial cells on polydimethylsiloxane (PDMS)/alumina (Al2 O3 ) composites and pure PDMS. The substrates were prepared from pure PDMS and its composites with 2.5, 5, 7.5, and 10 wt % Al2 O3 at a curing temperature of 50°C for 4 h. The substrates were then characterized by mechanical, structural, and morphological analyses. The cell adhesion, proliferation, and morphology of cultured bovine aortic endothelial (BAEC) cells on substrate materials were evaluated by using resazurin assay and 1,1'-dioctadecyl-1,3,3,3',3'-tetramethylindocarbocyanine perchlorate-acetylated LDL (Dil-Ac-LDL) cell staining, respectively. The composites (PDMS/2.5, 5, 7.5, and 10 wt % Al2 O3 ) exhibited higher stiffness than the pure PDMS substrate. The results also revealed that stiffer substrates promoted endothelial cell adhesion and proliferation and also induced spread morphology in the endothelial cells compared with lesser stiff substrates. Statistical analysis showed that the effect of time on cell proliferation depended on stiffness. Therefore, this study concludes that the addition of different Al2 O3 percentages to PDMS elevated substrate stiffness which in turn increased endothelial cell adhesion and proliferation significantly and induced spindle shape morphology in endothelial cells.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry*
Fulltext Iatrogenic aspiration of custom-made keel: a case report

Sharouny H, Omar RB

Iran Red Crescent Med J, 2014 Dec;16(12):e17066.
PMID: 25763237 DOI: 10.5812/ircmj.17066

INTRODUCTION: Laryngeal stenosis has various causes and treatment options. Endoscopic resection of the stenotic part with CO2 laser is one of the treatment options of laryngotracheal stenosis. Keels are useful for preventing adhesion formation, restenosis and web formation, which may happen during the later stage. They can be put in place either via the endoscopic approach or through a micro thyroidotomy and are held in place with a heavy suture through cricothyroid and thyrohyoid membranes. They are left in place for two to four weeks, and then removed through the endoscopic approach under general anesthetics.
CASE PRESENTATION: We report on a case of anterior glottis stenosis with keel aspiration for two weeks, after endoscopic CO2 laser resection of the stenotic section and keel placement. The patient was admitted to our center, where bronchoscopy was performed and the keel was removed. A new custom-made silastic keel was properly placed in raw areas and fixed to the skin with suture through the cricothyroid and thyrohyoid membranes. The keel was removed three weeks later.
CONCLUSIONS: Endoscopic keel placement should be done with heavy suture through cricothyroid and thyrohyoid membranes. Surgeons should suture the keel to the anterior laryngeal wall with specially designed Lichtenberger's needle-carriers to prevent complications such as keel aspiration, adhesion formation and imposing a second trip under general anesthetics, which put the patient at increased risk. The false vocal cord microflaps, as biological keels and a relatively new method may replace silastic keel placement in the future.

Matched MeSH terms: Dimethylpolysiloxanes
Fulltext Synthesis and Characterizations of Novel Ca-Mg-Ti-Fe-Oxides Based Ceramic Nanocrystals and Flexible Film of Polydimethylsiloxane Composite with Improved Mechanical and Dielectric Properties for Sensors

Tripathy A, Pramanik S, Manna A, Shah NF, Shasmin HN, Radzi Z, et al.

Sensors (Basel), 2016;16(3):292.
PMID: 26927116 DOI: 10.3390/s16030292

Armalcolite, a rare ceramic mineral and normally found in the lunar earth, was synthesized by solid-state step-sintering. The in situ phase-changed novel ceramic nanocrystals of Ca-Mg-Ti-Fe based oxide (CMTFOx), their chemical reactions and bonding with polydimethylsiloxane (PDMS) were determined by X-ray diffraction, infrared spectroscopy, and microscopy. Water absorption of all the CMTFOx was high. The lower dielectric loss tangent value (0.155 at 1 MHz) was obtained for the ceramic sintered at 1050 °C (S1050) and it became lowest for the S1050/PDMS nanocomposite (0.002 at 1 MHz) film, which was made by spin coating at 3000 rpm. The excellent flexibility (static modulus ≈ 0.27 MPa and elongation > 90%), viscoelastic property (tanδ = E″/E': 0.225) and glass transition temperature (Tg: -58.5 °C) were obtained for S1050/PDMS film. Parallel-plate capacitive and flexible resistive humidity sensors have been developed successfully. The best sensing performance of the present S1050 (3000%) and its flexible S1050/PDMS composite film (306%) based humidity sensors was found to be at 100 Hz, better than conventional materials.

Matched MeSH terms: Dimethylpolysiloxanes
Nano-silica embedded polydimethylsiloxane on interdigitated sensor as adhesive polymer for detecting lung cancer mutation

Abulaiti A, Salai A, Sun X, Yibulayin W, Gao Y, Gopinath SCB, et al.

Biotechnol Appl Biochem, 2021 Feb 12.
PMID: 33576539 DOI: 10.1002/bab.2122

Non-small cell lung cancer (NSCLC) incited by epidermal growth factor receptor (EGFR) mutation makes up ∼85% of lung cancer diagnosed and death cases worldwide. The presented study introduced an alternative approach in detecting EGFR mutation using nano-silica integrated with polydimethylsiloxane (PDMS) polymer on interdigitated electrode (IDE) sensor. A 400 μm gap-sized aluminum IDE was modified with nano-polymer layer, which was made up of silica nanoparticles and PDMS polymer. IDE and PDMS-coated IDE (PDMS/IDE) were imaged using electron microscopes that reveals its smooth and ideal sensor morphology. The nano-silica-integrated PDMS/IDE surface was immobilized with EGFR probe and target to specify the lung cancer detection. The sensor specificity was justified through the insignificant current readouts with one-base mismatch and noncomplementary targets. The sensitivity of nano-silica-integrated PDMS/IDE was examined with mutant target spiked in human serum, where the resulting current affirms the detection of EGFR mutation. Based on the slope of the calibration curve, the sensitivity of nano-silica-integrated PDMS/IDE was 2.24E-9 A M-1 . The sensor recognizes EGFR mutation lowest at 1 aM complementary mutant target; however, the detection limit obtained based on 3σ calculation is 10 aM with regression value of 0.97.

Matched MeSH terms: Dimethylpolysiloxanes
Determination of volatile organic compounds pollution sources in malaysian drinking water using multivariate analysis

Soh SC, Abdullah MP

Environ Monit Assess, 2007 Jan;124(1-3):39-50.
PMID: 16967208

A field investigation was conducted at all water treatment plants throughout 11 states and Federal Territory in Peninsular Malaysia. The sampling points in this study include treatment plant operation, service reservoir outlet and auxiliary outlet point at the water pipelines. Analysis was performed by solid phase micro-extraction technique with a 100 microm polydimethylsiloxane fibre using gas chromatography with mass spectrometry detection to analyse 54 volatile organic compounds (VOCs) of different chemical families in drinking water. The concentration of VOCs ranged from undetectable to 230.2 microg/l. Among all of the VOCs species, chloroform has the highest concentration and was detected in all drinking water samples. Average concentrations of total trihalomethanes (THMs) were almost similar among all states which were in the range of 28.4--33.0 microg/l. Apart from THMs, other abundant compounds detected were cis and trans-1,2-dichloroethylene, trichloroethylene, 1,2-dibromoethane, benzene, toluene, ethylbenzene, chlorobenzene, 1,4-dichlorobenzene and 1,2-dichloro - benzene. Principal component analysis (PCA) with the aid of varimax rotation, and parallel factor analysis (PARAFAC) method were used to statistically verify the correlation between VOCs and the source of pollution. The multivariate analysis pointed out that the maintenance of auxiliary pipelines in the distribution systems is vital as it can become significant point source pollution to Malaysian drinking water.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry
Optimization of headspace solid-phase microextraction for the determination of pesticide residues in vegetables and fruits

Chai M, Tan G, Lal A

Anal Sci, 2008 Feb;24(2):273-6.
PMID: 18270422

A headspace solid-phase microextraction method has been developed for the determination of 8 pesticides in vegetables and fruits by using gas chromatography with an electron capture detector. Two types of fibers (polyacrylate, 85 microm and polydimethylsiloxane, 100 microm) have been assayed and compared. The main factors: extraction and desorption parameters, ionic strength, and the effects of dilution and organic solvents, were studied and optimized. The optimized procedures resulted in more than 80% recovery for all the investigated vegetable and fruit samples with RSD values below 10%.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry
Low electric field DNA separation and in-channel amperometric detection by microchip capillary electrophoresis

Ghanim MH, Najimudin N, Ibrahim K, Abdullah MZ

IET Nanobiotechnol, 2014 Jun;8(2):77-82.
PMID: 25014078 DOI: 10.1049/iet-nbt.2012.0044

Miniaturisation of microchip capillary electrophoresis (MCE) is becoming an increasingly important research topic, particularly in areas related to micro total analysis systems or lab on a chip. One of the important features associated with the miniaturised MCE system is the portable power supply unit. In this work, a very low electric field MCE utilising an amperometric detection scheme was designed for use in DNA separation. The device was fabricated from a glass/polydimethylsiloxane hybrid engraved microchannel with platinum electrodes sputtered onto a glass substrate. Measurement was based on a three-electrode arrangement, and separation was achieved using a very low electric field of 12 V/cm and sample volume of 1.5 µl. The device was tested using two commercial DNA markers of different base pair sizes. The results are in agreement with conventional electrophoresis, but with improved resolution. The sensitivity consistently higher than 100 nA, and the separation time approximately 45 min, making this microchip an ideal tool for DNA analysis.

Matched MeSH terms: Dimethylpolysiloxanes/chemistry

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