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1.
Anal Chim Acta ; 1184: 339010, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34625258

RESUMO

This work proposed a novel and flexible immunosensor for highly selective and sensitive determination of cortisol in sweat. The flexible electrode was developed by transferring multi-walled carbon nanotubes (MWCNTs) film on polydimethylsiloxane (PDMS) substrate and subsequent electrochemical deposition of Au nanoparticles (AuNPs) on the MWCNTs surface. The obtained AuNPs/MWCNTs/PDMS electrode was then covalently immobilized with anti-cortisol monoclonal antibody (Anti-Cmab) and blocked with BSA. Scanning electron microscope confirmed that MWCNTs have been firmly combined with PDMS and AuNPs distributed uniformly on the surface of MWCNTs. The PDMS-based sensor possesses a good mechanical stability against stretching, bending and twisting, displaying stable electrochemical performance under deformation. After optimizing the analytical parameters, the developed immunosensor allowed a facile quantification of cortisol in the range of 1 fg/mL-1 µg/mL with a detection limit of 0.3 fg/mL. The cortisol immunosensor was further used to evaluate cortisol levels in human sweat, and the results corresponded closely with commercially available chemiluminescence immunoassay (CLIA) method. Results indicated that the new cortisol immunosensor could provide an effective tool for the noninvasive, point of care measurement of sweat cortisol levels and is promise to be a wearable biosensor for the healthy monitoring.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Nanotubos de Carbono , Dimetilpolisiloxanos , Técnicas Eletroquímicas , Ouro , Humanos , Hidrocortisona , Imunoensaio , Suor
2.
Shanghai Kou Qiang Yi Xue ; 30(3): 253-257, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34476440

RESUMO

PURPOSE: To investigate the effects of extracellular matrix stiffness on proliferation and osteogenic differentiation of dental pulp stem cells (DPSCs) in polydimethylsiloxane (PDMS)-based cell culture substrate model. METHODS: The premolars removed during orthodontic treatment in Changzhou NO.2 People's Hospital were collected for DPSCs culture. PDMS matrix membranes were prepared, and divided into three groups according to the different stiffness degrees, group A (binder/hardener: 10∶1; 135 kPa), group B (binder/hardener: 20∶1; 54 kPa), and group C (binder/hardener: 30∶1; 16 kPa). Group free from PDMS was set as control group. Thereafter, DPSCs cells were cultured on PDMS matrix, and various indexes were detected. The proliferation rate of DPSCs was detected by CCK-8, the osteogenic differentiation of DPSCs was detected by alizarin red staining, and the protein expression levels of osteocalcin(OCN), RUNX2, Wnt1 and ß-catenin were detected by Western blot. The data were processed with SPSS 22.0 software package. RESULTS: Alizarin red staining showed that DPSCs cells in group A had obvious morphological changes, and the cell arrangement showed obvious orientation, its morphology gradually changed from polygon and spindle shape to square shape, and calcified nodules were also observed. The number of calcified nodules among four groups were the most in the group A, followed by group B and group C, which was the lowest in control group, with significant difference (P<0.05). The cell proliferation rate and the expression of OCN, RUNX2, Wnt1 and ß-catenin were the highest in group A, followed by group B and group C, which was the lowest in control group, with significant difference(P<0.05). CONCLUSIONS: The extracellular matrix with high stiffness may promote the proliferation and osteogenic differentiation of DPSCs by activating Wnt/ß-catenin signaling pathway, which may provide a theoretical basis for periodontal tissue engineering.


Assuntos
Polpa Dentária , Osteogênese , Diferenciação Celular , Proliferação de Células , Células Cultivadas , Dimetilpolisiloxanos , Matriz Extracelular , Humanos , Células-Tronco
3.
Handchir Mikrochir Plast Chir ; 53(5): 482-487, 2021 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-34583404

RESUMO

Silastic spacer replacement for the treatment of destroyed finger joints due to degenerative, post-traumatic or rheumatoid osteoarthritis has been well established for years. In acute severely traumatized hands silastic spacer replacement is seldomly performed We report five consecutive patients in whom a defect injury of a finger joint was replaced by a silicone implant without complications during primary care. We reviewed all our patients with a follow up of at least 8 months. In all patients healing was uneventful, with no infections and a functional range of motion. No patient complained about instability. With the right patient selection, joint replacement with silastic spacers is a valuable alternative to arthrodesis in acute destroyed finger joints.


Assuntos
Artroplastia de Substituição de Dedo , Artroplastia de Substituição , Prótese Articular , Dimetilpolisiloxanos , Articulações dos Dedos/diagnóstico por imagem , Articulações dos Dedos/cirurgia , Seguimentos , Humanos , Amplitude de Movimento Articular
4.
Sensors (Basel) ; 21(18)2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34577282

RESUMO

A flexible strain sensor which integrates both pressure sensing and tension sensing functions is demonstrated with an active layer comprising of polydimethy-lsiloxane (PDMS) elastomer, liquid crystal (LC), and multi-walled carbon nanotubes (MWCNTs). The introduction of LC improves the agglomeration of MWCNTs in PDMS and decreases Young's modulus of flexible resistive sensors. The tension/pressure integrated resistive sensor not only shows a broad tensile sensing range of 140% strain but also shows a good sensitivity of the gauge factor, 40, with tensile force. Besides, the tension/pressure integrated resistive sensor also shows good linearity and sensitivity under pressure. The resistance of the pressure sensor increases as the applied pressure increases because of the decrease in the cross-sectional area of the path. The sensor also shows good hydrophobic properties which may help it to work under complex environment. The tension/pressure integrated sensor shows great promising applications in electronic skins and wearable devices.


Assuntos
Cristais Líquidos , Nanotubos de Carbono , Dispositivos Eletrônicos Vestíveis , Dimetilpolisiloxanos , Módulo de Elasticidade
5.
Food Res Int ; 148: 110632, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34507775

RESUMO

In this study, a comparison of the efficiency of the commercially available polydimethylsiloxane/divinylbenzene (PDMS/DVB) overcoated (OC) fiber used in direct immersion (DI) or in headspace (HS), has been performed by extracting volatiles through solid-phase microextraction (SPME) from a red wine and from a wine model to confirm the results. It was also investigated if a combination of DI followed by HS in a single assay (DI-HS) can provide improvements as compared to the use in DI or in HS only. Furthermore, the use of OC fiber in HS mode was compared with the use of the triphasic phase (TP, in PDMS/CAR/DVB), known to provide good results in this application. To have information also on fiber specificity, the detected analytes were subdivided into three classes depending on their boiling point. Results show that: OC fiber gives slightly better performance as compared to TP fiber, demonstrating a high efficiency of the OC fiber also in HS mode. Then, comparing the use of the commercial OC fiber in HS, DI and in the combined DI-HS mode, explored for the first time in this study to extract volatiles from wine, the combination DI-HS resulted to provide a more balanced efficiency for all the three groups of analytes, thus being a good compromise when the analytes have a broad range of volatility. Principal component analysis (PCA) and the design of experiment (DoE) were exploited to plan experiments and to help interpreting the results, highlighting that the combined DI-HS approach can be successfully applied to the characterization of wines and of other matrices, where analytes of interest have a wide range of volatility.


Assuntos
Microextração em Fase Sólida , Vinho , Dimetilpolisiloxanos , Cromatografia Gasosa-Espectrometria de Massas , Imersão , Espectrometria de Massas , Compostos de Vinila , Vinho/análise
6.
ACS Appl Mater Interfaces ; 13(33): 39135-39141, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34374274

RESUMO

Many physiochemical properties of the extracellular matrix (ECM) of muscle tissues, such as nanometer scale dimension, nanotopography, negative charge, and elasticity, must be carefully reproduced to fabricate scaffold materials mimicking muscle tissues. Hence, we developed a muscle tissue ECM-mimicking scaffold using Mo6S3I6 inorganic molecular wires (IMWs). Composed of bio-essential elements and having a nanofibrous structure with a diameter of ∼1 nm and a negative surface charge with high stability, Mo6S3I6 IMWs are ideal for mimicking natural ECM molecules. Once Mo6S3I6 IMWs were patterned on a polydimethylsiloxane surface with an elasticity of 1877.1 ± 22.2 kPa, that is, comparable to that of muscle tissues, the proliferation and α-tubulin expression of myoblasts enhanced significantly. Additionally, the repetitive one-dimensional patterns of Mo6S3I6 IMWs induced the alignment and stretching of myoblasts with enhanced α-tubulin expression and differentiation into myocytes. This study demonstrates that Mo6S3I6 IMWs are promising for mimicking the ECM of muscle tissues.


Assuntos
Materiais Biomiméticos/química , Dimetilpolisiloxanos/química , Matriz Extracelular/metabolismo , Nanofios/química , Tecidos Suporte/química , Materiais Biomiméticos/metabolismo , Diferenciação Celular , Proliferação de Células/efeitos dos fármacos , Humanos , Iodo/química , Molibdênio/química , Músculos/citologia , Mioblastos/citologia , Mioblastos/metabolismo , Enxofre/química , Propriedades de Superfície , Engenharia Tecidual , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo
7.
Sensors (Basel) ; 21(16)2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34451087

RESUMO

The advanced and widespread use of microfluidic devices, which are usually fabricated in polydimethylsiloxane (PDMS), requires the integration of many sensors, always compatible with microfluidic fabrication processes. Moreover, current limitations of the existing optical and electrochemical oxygen sensors regarding long-term stability due to sensor degradation, biofouling, fabrication processes and cost have led to the development of new approaches. Thus, this manuscript reports the development, fabrication and characterization of a low-cost and highly sensitive dissolved oxygen optical sensor based on a membrane of PDMS doped with platinum octaethylporphyrin (PtOEP) film, fabricated using standard microfluidic materials and processes. The excellent mechanical and chemical properties (high permeability to oxygen, anti-biofouling characteristics) of PDMS result in membranes with superior sensitivity compared with other matrix materials. The wide use of PtOEP in sensing applications, due to its advantage of being easily synthesized using microtechnologies, its strong phosphorescence at room temperature with a quantum yield close to 50%, its excellent Strokes Shift as well as its relatively long lifetime (75 µs), provide the suitable conditions for the development of a miniaturized luminescence optical oxygen sensor allowing long-term applications. The influence of the PDMS film thickness (0.1-2.5 mm) and the PtOEP concentration (363, 545, 727 ppm) in luminescent properties are presented. This enables to achieve low detection levels in a gas media range from 0.5% up to 20%, and in liquid media from 0.5 mg/L up to 3.3 mg/L at 1 atm, 25 °C. As a result, we propose a simple and cost-effective system based on a LED membrane photodiode system to detect low oxygen concentrations for in situ applications.


Assuntos
Platina , Porfirinas , Dimetilpolisiloxanos , Oxigênio
8.
Int J Mol Sci ; 22(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34360861

RESUMO

In response to the demand for high-performance materials, epoxy thermosetting and its composites are widely used in various industries. However, their poor toughness, resulting from the high crosslinking density of the epoxy network, must be improved to expand their application to the manufacturing of flexible products. In this study, ductile epoxy thermosetting was produced using thiol compounds with functionalities of 2 and 3 as curing agents. The mechanical properties of the epoxy were further enhanced by incorporating fumed silica into it. To increase the filler dispersion, epoxide-terminated polydimethylsiloxane was synthesized and used as a composite component. Thanks to the polysiloxane-silica interaction, the nanosilica was uniformly dispersed in the epoxy composites, and their mechanical properties improved with increasing fumed silica content up to 5 phr (parts per hundred parts of epoxy resin). The toughness and impact strength of the composite containing 5 phr nanosilica were 517 (±13) MJ/m3 and 69.8 (±1.3) KJ/m2, respectively.


Assuntos
Resinas Compostas/síntese química , Resinas Epóxi/síntese química , Dimetilpolisiloxanos/química , Teste de Materiais , Dióxido de Silício/química , Propriedades de Superfície , Resistência à Tração
9.
J Phys Chem Lett ; 12(33): 8072-8079, 2021 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-34406018

RESUMO

Mastering mechanical properties of polymers at nanometer scale is highly demanded yet remains challenging. Pioneering advances determined Young's modulus in ultrathin polymer films and attained unprecedented results including rubbery stiffening. However, many viscoelastic properties such as dynamic mechanical behavior of freestanding nanoconfined polymer films are still unknown. Here we demonstrate striking changes of stiffness and the ratio between elastic and viscous responses in thin PDMS films, using a microvibrational system which enables direct measurements of dynamic stress-strain relation of freestanding films. The results show that elastic modulus is enhanced by a factor of 135 in 50 nm films than the bulk, while the viscous response substantially increases at strains >0.05 in 125 nm films. These observations exhibit significant alterations of viscoelasticity under nanoconfinement. With insights on the underlying mechanism of these results, this study is expected to provide new evidence toward gaining a comprehensive understanding of nanoconfinement effect of soft matter.


Assuntos
Elastômeros/química , Nanotecnologia , Dimetilpolisiloxanos/química , Elasticidade , Fenômenos Mecânicos , Membranas Artificiais , Viscosidade
10.
Langmuir ; 37(36): 10732-10740, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34464138

RESUMO

Plasma-treated poly(dimethylsiloxane) (PDMS)-supported lipid bilayers are used as functional tools for studying cell membrane properties and as platforms for biotechnology applications. Self-spreading is a versatile method for forming lipid bilayers. However, few studies have focused on the effect of plasma treatment on self-spreading lipid bilayer formation. In this paper, we performed lipid bilayer self-spreading on a PDMS surface with different treatment times. Surface characterization of PDMS treated with different treatment times is evaluated by AFM and SEM, and the effects of plasma treatment of the PDMS surface on lipid bilayer self-spreading behavior is investigated by confocal microscopy. The front-edge velocity of lipid bilayers increases with the plasma treatment time. By theoretical analyses with the extended-DLVO modeling, we find that the most likely cause of the velocity change is the hydration repulsion energy between the PDMS surface and lipid bilayers. Moreover, the growth behavior of membrane lobes on the underlying self-spreading lipid bilayer was affected by topography changes in the PDMS surface resulting from plasma treatment. Our findings suggest that the growth of self-spreading lipid bilayers can be controlled by changing the plasma treatment time.


Assuntos
Dimetilpolisiloxanos , Bicamadas Lipídicas , Propriedades de Superfície
11.
Lab Chip ; 21(18): 3509-3519, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34346471

RESUMO

Microfluidic organ-on-a-chip (Organ Chip) cell culture devices are often fabricated using polydimethylsiloxane (PDMS) because it is biocompatible, transparent, elastomeric, and oxygen permeable; however, hydrophobic small molecules can absorb to PDMS, which makes it challenging to predict drug responses. Here, we describe a combined simulation and experimental approach to predict the spatial and temporal concentration profile of a drug under continuous dosing in a PDMS Organ Chip containing two parallel channels separated by a porous membrane that is lined with cultured cells, without prior knowledge of its log P value. First, a three-dimensional finite element model of drug loss into the chip was developed that incorporates absorption, adsorption, convection, and diffusion, which simulates changes in drug levels over time and space as a function of potential PDMS diffusion coefficients and log P values. By then experimentally measuring the diffusivity of the compound in PDMS and determining its partition coefficient through mass spectrometric analysis of the drug concentration in the channel outflow, it is possible to estimate the effective log P range of the compound. The diffusion and partition coefficients were experimentally derived for the antimalarial drug and potential SARS-CoV-2 therapeutic, amodiaquine, and incorporated into the model to quantitatively estimate the drug-specific concentration profile over time measured in human lung airway chips lined with bronchial epithelium interfaced with pulmonary microvascular endothelium. The same strategy can be applied to any device geometry, surface treatment, or in vitro microfluidic model to simulate the spatial and temporal gradient of a drug in 3D without prior knowledge of the partition coefficient or the rate of diffusion in PDMS. Thus, this approach may expand the use of PDMS Organ Chip devices for various forms of drug testing.


Assuntos
COVID-19 , Preparações Farmacêuticas , Dimetilpolisiloxanos , Humanos , Microfluídica , SARS-CoV-2
12.
Biomacromolecules ; 22(9): 3769-3779, 2021 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-34432419

RESUMO

Colorimetric starch film containing anthocyanins is extensively used in eco-friendly intelligent food packaging, but its high water wettability limits its practical application in the food industry. Herein, a super anti-wetting colorimetric starch film was prepared by surface modification with a nano-starch/poly(dimethylsiloxane) (PDMS) composite coating. The water sensitivity, optical properties, mechanical properties, surface morphology, and surface chemical composition of this film were systemically investigated by multiple methods. The obtained film exhibited an extremely high water contact angle (152.46°) and low sliding angle (8.15°) owing to the hierarchical micro-/nanostructure formed by nano-starch aggregates combined with the low-surface-energy PDMS covering. The anti-wettability, optical barrier, and mechanical properties of this film were also significantly improved. The self-cleaning and liquid-food-repelling abilities of this film were comprehensively confirmed. Moreover, this super anti-wetting colorimetric starch film can be applied to monitor the freshness of aquatic products without being disabled by water.


Assuntos
Antocianinas , Amido , Colorimetria , Dimetilpolisiloxanos , Molhabilidade
13.
Colloids Surf B Biointerfaces ; 207: 112003, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34343909

RESUMO

Marine biofouling of ship hulls and ocean structures causes enormous economic losses due to increased frictional drag. Thus, efforts have been exerted worldwide to eliminate biofouling. In addition, a strong demand exists for the development of a cost-effective and eco-friendly anti-biofouling coating technology. Thus, erucamide-polydimethylsiloxane (EP) coating is proposed in this study. EP exhibits a hydrophobic surface as the erucamide content and drag reduction effect increase. In this study, the drag reduction effect of the EP 2.5 is better than that of glass and polydimethylsiloxane (PDMS) surfaces. Moreover, the proposed EP coatings are observed to prevent the biofouling induced by bacteria (E. coli) and brown algae (Cladosiphon sp.). In addition, through a marine field test, the anti-biofouling effect of the EP surface is found to be better than the previously studied oleamide-PDMS (OP) surface. In the marine field test, the EP 2.5 demonstrates superior anti-biofouling performance for 5.5 months under real marine environment. The proposed eco-friendly EP coating method could be applicable to marine vehicles that require effective drag reduction and anti-biofouling properties.


Assuntos
Incrustação Biológica , Incrustação Biológica/prevenção & controle , Dimetilpolisiloxanos , Ácidos Erúcicos , Escherichia coli , Propriedades de Superfície
14.
Sensors (Basel) ; 21(15)2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34372305

RESUMO

Flexible pressure sensors with piezoresistive polymer composites can be integrated into elastomers to measure pressure changes in sealings, preemptively indicating a replacement is needed before any damage or leakage occurs. Integrating small percentages of high aspect ratio multi-walled carbon nanotubes (MWCNTs) into polymers does not significantly change its mechanical properties but highly affects its electrical properties. This research shows a pressure sensor based on homogeneous dispersed MWCNTs in polydimethylsiloxane with a high sensitivity region (0.13% kPa-1, 0-200 kPa) and sensitive up to 500 kPa. A new 3D-printed mold is developed to directly deposit the conductive polymer on the electrode structures, enabling sensor thicknesses as small as 100 µm.


Assuntos
Nanotubos de Carbono , Dimetilpolisiloxanos , Condutividade Elétrica , Eletrodos , Polímeros
15.
Colloids Surf B Biointerfaces ; 206: 111957, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34216853

RESUMO

Silicone hydrogel lenses were prepared by copolymerizing PDMS-PEGMA macromer (PGP) with various combinations of DMA, NVP, and PEGMA through UV initiated polymerization process. The resultant PGP macromer were characterized by gel permeation chromatography (GPC), and scanning electron microscope (SEM-EDS). Characterization of all the resultant co-polymers included Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), equilibrium water content (EWC), oxygen permeability (Dk), optical transparency, contact angle, mechanical properties, zeta potential, protein deposition, and cytotoxicity. The results show that higher content of hydrophilic polymers increased water uptake ability as well as improved hydrophilicity and modulus of silicone hydrogel lenses; however, oxygen permeability decreased with the decrease of PDMS content (145 barrers of PGP to 37 barrers of DP0). In addition, these silicone hydrogel lenses exhibited relatively optical transparency, anti-protein deposition, and non-cytotoxic according to an in vitro L929 fibroblast assay. Therefore, these silicone hydrogel polymers would be applicable for making contact lens.


Assuntos
Lentes de Contato Hidrofílicas , Lentes de Contato , Dimetilpolisiloxanos , Hidrogel de Polietilenoglicol-Dimetacrilato , Hidrogéis , Interações Hidrofóbicas e Hidrofílicas , Polímeros , Silicones
16.
Biosensors (Basel) ; 11(6)2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34201174

RESUMO

The development of in situ analytical devices has gained outstanding scientific interest. A solid sensing membrane composed of 1,2-naphthoquinone-4-sulfonate (NQS) derivatizing reagent embedded into a polymeric polydimethylsiloxane (PDMS) composite was proposed for in situ ammonium (NH4+) and urea (NH2CONH2) analysis in water and urine samples, respectively. Satisfactory strategies were also applied for urease-catalyzed hydrolysis of urea, either in solution or glass-supported urease immobilization. Using diffuse reflectance measurements combined with digital image processing of color intensity (RGB coordinates), qualitative and quantitative analyte detection was assessed after the colorimetric reaction took place inside the sensing membrane. A suitable linear relationship was found between the sensor response and analyte concentration, and the results were validated by a thymol-PDMS-based sensor based on the Berthelot reaction. The suggested sensing device offers advantages such as rapidity, versatility, portability, and employment of non-toxic reagents that facilitate in situ analysis in an energy-efficient manner.


Assuntos
Naftoquinonas/química , Ureia/metabolismo , Urease/metabolismo , Colorimetria , Dimetilpolisiloxanos , Polímeros , Urease/análise , Água/química
17.
ACS Biomater Sci Eng ; 7(8): 3648-3657, 2021 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-34283567

RESUMO

A liver-on-a-chip (liver-chip) is a microfluidic device carrying liver cells such as human hepatocytes. It is used to reproduce a part of liver function. Many microfluidic devices are composed of polydimethylsiloxane (PDMS), which is a type of silicone elastomer. PDMS is easy to process and suitable for cell observation, but its high hydrophobicity carries the risk of drug absorption. In this study, we evaluated drug absorption to the PDMS device and investigated the drug responsiveness of human hepatocytes cultured in the PDMS device (hepatocyte-chips). First, the absorption rates of 12 compounds to the PDMS device were measured. The absorption rates of midazolam, bufuralol, cyclosporine A, and verapamil were 92.9, 71.7, 71.4, and 99.6%, respectively, but the other compounds were poorly absorbed. Importantly, the absorption rate of the compounds was correlated with their octanol/water distribution coefficient (log D) values (R2 = 0.76). Next, hepatocyte-chips were used to examine the response to drugs, which are typically used to evaluate hepatic functions. Using the hepatocyte-chips, we could confirm the responsiveness of drugs including cytochrome P450 (CYP) inducers and farnesoid X receptor (FXR) ligands. We believe that our findings will contribute to drug discovery research using PDMS-based liver-chips.


Assuntos
Dispositivos Lab-On-A-Chip , Pesquisa Farmacêutica , Dimetilpolisiloxanos , Hepatócitos , Humanos , Interações Hidrofóbicas e Hidrofílicas
18.
J Appl Clin Med Phys ; 22(8): 72-82, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34231949

RESUMO

PURPOSE: Eye plaques are widely used for ocular melanoma and provide an effective alternative to enucleation with adequate tumor control. A COMS plaque utilizes a Silastic insert for precise positioning of the radioactive seeds with respect to the scleral surface of the eye; however, due to manufacturing variability, the insert may unintentionally increase or decrease the distance between the sources and tumor. The purpose of this work is to provide guidance in measuring and identifying outliers in Silastic inserts. The importance of regular quality assurance (QA) is illustrated in an experience where a systematic problem was detected and the manufacturer's 22-mm mold was corrected. METHODS: A detailed description of the molds and manufacturing process used to produce Silastic inserts is provided, including photographs of the process steps. The variability in Silastic insert production was evaluated by measuring the thickness of 124 Silastic inserts. An estimate of how the observed Silastic thickness discrepancies impact the dose to the tumor and critical eye structures was performed using homogeneous dose calculations. A standard QA protocol was developed to guide the clinical user. RESULTS: Thickness of the measured Silastic inserts ranged from 1.22 to 2.67 mm, demonstrating variation from the 2.25 mm standard. Six of the 22-mm inserts were outliers (Δthickness >3 standard deviations) and were excluded from the statistics. The outliers were investigated with the help of the manufacturer, who discovered that a systematic error was accidentally introduced into the 22-mm mold. CONCLUSIONS: Due to manufacturing errors or variability, the Silastic inserts used in COMS eye plaques may be thicker or thinner than the design standard. Such variations may impact tumor control or increase the risk of normal tissue side effects. A standardized QA program is recommended to detect variations and communicate unusual findings to the manufacturer.


Assuntos
Braquiterapia , Neoplasias Oculares , Dimetilpolisiloxanos , Neoplasias Oculares/radioterapia , Humanos , Radioisótopos do Iodo , Método de Monte Carlo , Dosagem Radioterapêutica
19.
Talanta ; 233: 122514, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215129

RESUMO

Channel-based microfluidic devices integrating the separation step and detection system are key factors to expand microanalysis application. However, these devices still depend on macroscale external equipment for pre-treatment of the sample, separation, or detection. The integration of all steps in only one stage is critical to improving feasibility. Herein, we use a low-cost protocol to solve part of the challenge by designing a dual-mode system onto single polydimethylsiloxane (PDMS)-based platform - overall dimensions of 65 mm length × 20 mm width × 14 mm height and the inner diameter of 297±10 µm height × 605±19 µm width - for column-free separation and simultaneous detection. As a proof-of-concept, we used this all-in-one PDMS platform to separate - without the packet-based phase - and determine salicylic acid (SA) and caffeine (CAF) with a detection limit of 0.20 and 0.18 µmol L-1 and quantification limit of 0.70 and 0.60 µmol L-1 for SA and CAF, respectively. We separated the mixture using forced convection into a chemically treated microchannel while detecting the analytes in amperometric mode. Here, we report new insights into how integrating analytes separation and further electroanalysis into a single miniaturized device.


Assuntos
Dimetilpolisiloxanos , Dispositivos Lab-On-A-Chip
20.
Molecules ; 26(12)2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34204423

RESUMO

The exploration of nonhazardous nanoparticles to fabricate a template-driven superhydrophobic surface is of great ecological importance for oil/water separation in practice. In this work, nano-hydroxyapatite (nano-HAp) with good biocompatibility was easily developed from discarded oyster shells and well incorporated with polydimethylsiloxane (PDMS) to create a superhydrophobic surface on a polyurethane (PU) sponge using a facile solution-immersion method. The obtained nano-HAp coated PU (nano-HAp/PU) sponge exhibited both excellent oil/water selectivity with water contact angles of over 150° and higher absorption capacity for various organic solvents and oils than the original PU sponge, which can be assigned to the nano-HAp coating surface with rough microstructures. Moreover, the superhydrophobic nano-HAp/PU sponge was found to be mechanically stable with no obvious decrease of oil recovery capacity from water in 10 cycles. This work presented that the oyster shell could be a promising alternative to superhydrophobic coatings, which was not only beneficial to oil-containing wastewater treatment, but also favorable for sustainable aquaculture.


Assuntos
Exoesqueleto/química , Durapatita/química , Recuperação e Remediação Ambiental/métodos , Exoesqueleto/metabolismo , Animais , Carbonato de Cálcio/química , Dimetilpolisiloxanos/química , Durapatita/isolamento & purificação , Interações Hidrofóbicas e Hidrofílicas , Nanopartículas/química , Óleos/química , Ostreidae/metabolismo , Poluição por Petróleo/análise , Poluição por Petróleo/prevenção & controle , Solventes , Propriedades de Superfície , Água/química , Purificação da Água/métodos
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