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1.
Artigo em Inglês | MEDLINE | ID: mdl-35665644

RESUMO

This work proposes a new method for biomonitoring studies focused on the screening and quantification of xenobiotics in blood-derived samples. The performance of a polydimethylsiloxane/divinylbenzene/polydimethylsiloxane (PDMS/DVB/PDMS) biocompatible extraction phase was investigated for extraction of pesticides and pharmaceuticals from plasma samples via direct immersion solid-phase microextraction (SPME) prior to gas chromatography-mass spectrometry. Under the optimum extraction settings, which included an attentive optimization of the fiber rinsing conditions, the microextraction device was able to endure 100 consecutive extractions from undiluted and diluted plasma with an overall reproducibility up to 28% for all the analytes tested, except chlorpyrifos-methyl. Optimized conditions were used to validate a quantitative method using matrix-matched calibration with isotopically labeled internal standard correction. Accuracy and precision values obtained for analysis of bovine plasma were within 96-132% and 0.05-5.82% respectively. LLOQs for all the analytes were at 1 µg L-1 and LDR ranged within 1-100 µg L-1. The applicability of this method to plasma from different species (human, rat, rabbit) was also investigated. This work represents the first step toward broader use of the biocompatible PDMS/DVB/PDMS extraction phases for analysis of multiclass xenobiotics in plasma and other complex biofluids.


Assuntos
Microextração em Fase Sólida , Xenobióticos , Animais , Bovinos , Dimetilpolisiloxanos/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Plasma , Coelhos , Ratos , Reprodutibilidade dos Testes , Microextração em Fase Sólida/métodos
2.
Molecules ; 27(11)2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-35684326

RESUMO

Particle deposition on the surface of a drying chamber is the main drawback in the spray drying process, reducing product recovery and affecting the quality of the product. In view of this, the potential application of chemical surface modification to produce a hydrophobic surface that reduces the powder adhesion (biofouling) on the wall of the drying chamber is investigated in this study. A hydrophobic polydimethylsiloxane (PDMS) solution was used in the vertical dipping method at room temperature to determine the optimum coating parameters on borosilicate glass and stainless steel substrates, which were used to mimic the wall surface of the drying chamber, to achieve highly hydrophobic surfaces. A single-factor experiment was used to define the range of the PDMS concentration and treatment duration using the Response Surface Methodology (RSM). The Central Composite Rotatable Design (CCRD) was used to study the effects of the concentration of the PDMS solution (X1, %) and the treatment duration (X2, h) on the contact angle of the substrates (°), which reflected the hydrophobicity of the surface. A three-dimensional response surface was constructed to examine the influence of the PDMS concentration and treatment duration on contact angle readings, which serve as an indicator of the surface's hydrophobic characteristics. Based on the optimisation study, the PDMS coating for the borosilicate glass achieved an optimum contact angle of 99.33° through the combination of a PDMS concentration of X1 = 1% (w/v) and treatment time of X2 = 4.94 h, while the PDMS coating for the stainless steel substrate achieved an optimum contact angle of 98.31° with a PDMS concentration of X1 = 1% (w/v) and treatment time of X2 = 1 h. Additionally, the infrared spectra identified several new peaks that appeared on the PDMS-treated surfaces, which represented the presence of Si-O-Si, Si-CH3, CH2, and CH3 functional groups for the substrates coated with PDMS. Furthermore, the surface morphology analysis using the Field Emission Scanning Electron Microscopy (FESEM) showed the presence of significant roughness and a uniform nanostructure on the surface of the PDMS-treated substrates, which indicates the reduction in wettability and the potential effect of unwanted biofouling on the spray drying chamber. The application of PDMS and PTFE on the optimally coated substrates successfully reduced the amount of full cream milk particles that adhered to the surface. The low surface energy of the treated surface (19-27 mJ/m2) and the slightly higher surface tension of the full cream milk (54-59 mJ/m2) resulted in a high contact angle (102-103°) and reduced the adhesion work on the treated substrates (41-46 mJ/m2) as compared to the native substrates.


Assuntos
Dimetilpolisiloxanos , Aço Inoxidável , Dimetilpolisiloxanos/química , Interações Hidrofóbicas e Hidrofílicas , Propriedades de Superfície , Molhabilidade
3.
Molecules ; 27(11)2022 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-35684423

RESUMO

Limited tissue selectivity and targeting of anticancer therapeutics in systemic administration can produce harmful side effects in the body. Various polymer nano-vehicles have been developed to encapsulate therapeutics and prevent premature drug release. Dually responsive polymeric vesicles (polymersomes) assembled from temperature-/pH-sensitive block copolymers are particularly interesting for the delivery of encapsulated therapeutics to targeted tumors and inflamed tissues. We have previously demonstrated that temperature-responsive poly(N-vinylcaprolactam) (PVCL)-b-poly(dimethylsiloxane) (PDMS)-b-PVCL polymersomes exhibit high loading efficiency of anticancer therapeutics in physiological conditions. However, the in-vivo toxicity of these polymersomes as biocompatible materials has not yet been explored. Nevertheless, developing an advanced therapeutic nanocarrier must provide the knowledge of possible risks from the material's toxicity to support its future clinical research in humans. Herein, we studied pH-induced degradation of PVCL10-b-PDMS65-b-PVCL10 vesicles in-situ and their dually (pH- and temperature-) responsive release of the anticancer drug, doxorubicin, using NMR, DLS, TEM, and absorbance spectroscopy. The toxic potential of the polymersomes was evaluated in-vivo by intravenous injection (40 mg kg-1 single dose) of PVCL10-PDMS65-PVCL10 vesicles to mice. The sub-acute toxicity study (14 days) included gravimetric, histological, and hematological analyses and provided evidence for good biocompatibility and non-toxicity of the biomaterial. These results show the potential of these vesicles to be used in clinical research.


Assuntos
Portadores de Fármacos , Polímeros , Animais , Materiais Biocompatíveis , Caprolactama/análogos & derivados , Dimetilpolisiloxanos , Doxorrubicina/química , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos , Camundongos , Polímeros/química
4.
Molecules ; 27(11)2022 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-35684515

RESUMO

At this time, the development of advanced elastic dielectric materials for use in organic devices, particularly in organic field-effect transistors, is of considerable interest to the scientific community. In the present work, flexible poly(dimethylsiloxane) (PDMS) specimens cross-linked by means of ZnCl2-bipyridine coordination with an addition of 0.001 wt. %, 0.0025 wt. %, 0.005 wt. %, 0.04 wt. %, 0.2 wt. %, and 0.4 wt. % of gold nanoparticles (AuNPs) were prepared in order to understand the effect of AuNPs on the electrical properties of the composite materials formed. The broadband dielectric spectroscopy measurements revealed one order of magnitude decrease in loss tangent, compared to the coordinated system, upon an introduction of 0.001 wt. % of AuNPs into the polymeric matrix. An introduction of AuNPs causes damping of conductivity within the low-temperature range investigated. These effects can be explained as a result of trapping the Cl- counter ions by the nanoparticles. The study has shown that even a very low concentration of AuNPs (0.001 wt. %) still brings about effective trapping of Cl- counter anions, therefore improving the dielectric properties of the investigated systems. The modification proposed reveals new perspectives for using AuNPs in polymers cross-linked by metal-ligand coordination systems.


Assuntos
Ouro , Nanopartículas Metálicas , Dimetilpolisiloxanos/química , Ouro/química , Ligantes , Nanopartículas Metálicas/química , Polímeros/química
5.
Sensors (Basel) ; 22(11)2022 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-35684658

RESUMO

This work presents research on unique optofluidic systems in the form of air channels fabricated in PDMS and infiltrated with liquid crystalline material. The proposed LC:PDMS structures represent an innovative solution due to the use of microchannel electrodes filled with a liquid metal alloy. The latter allows for the easy and dynamic reconfiguration of the system and eliminates technological issues experienced by other research groups. The paper discusses the design, fabrication, and testing methods for tunable LC:PDMS structures. Particular emphasis was placed on determining their properties after applying an external electric field, depending on the geometrical parameters of the system. The conclusions of the performed investigations may contribute to the definition of guidelines for both LC:PDMS devices and a new class of potential sensing elements utilizing polymers and liquid crystals in their structures.


Assuntos
Dimetilpolisiloxanos , Cristais Líquidos , Dimetilpolisiloxanos/química , Eletricidade , Cristais Líquidos/química , Polímeros/química
6.
Sensors (Basel) ; 22(11)2022 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-35684803

RESUMO

Wearable sensors are gaining attention in human health monitoring applications, even if their usability is limited due to battery need. Flexible nanogenerators (NGs) converting biomechanical energy into electrical energy offer an interesting solution, as they can supply the sensors or extend the battery lifetime. Herein, flexible generators based on lead-free barium titanate (BaTiO3) and a polydimethylsiloxane (PDMS) polymer have been developed. A comparative study was performed to investigate the impact of multiwalled carbon nanotubes (MWCNTs) via structural, morphological, electrical, and electromechanical measurements. This study demonstrated that MWCNTs boosts the performance of the NG at the percolation threshold. This enhancement is attributed to the enhanced conductivity that promotes charge transfer and enhanced mechanical property and piezoceramics particles distribution. The nanogenerator delivers a maximum open-circuit voltage (VOC) up to 1.5 V and output power of 40 nW, which is two times higher than NG without MWCNTs. Additionally, the performance can be tuned by controlling the composite thickness and the applied frequency. Thicker NG shows a better performance, which enlarges their potential use for harvesting biomechanical energy efficiently up to 11.22 V under palm striking. The voltage output dependency on temperature was also investigated. The results show that the output voltage changes enormously with the temperature.


Assuntos
Nanotubos de Carbono , Polímeros , Compostos de Bário , Dimetilpolisiloxanos , Fontes de Energia Elétrica , Humanos , Titânio
7.
J Colloid Interface Sci ; 623: 832-844, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35636292

RESUMO

Marine optical instruments are commonly suffering serious biofouling problem caused by the adhesion of marine microorganisms, which severely affects the instruments to monitor the marine environment. Herein, we developed a robust solid slippery surface (SSS) by fabricated a covalently attached polydimethylsiloxane (PDMS) layer on glass substrate to solve the biofouling problem of marine optical instrument windows. The SSS could effectively inhibit the settlements of marine microorganism (bacteria and alga) in various environmental conditions, resulting from the high flexibility of PDMS molecular chains, and thus could maintain its high underwater-transparency. The antifouling mechanism of SSS was results from the weak nonspecific electrostatic Lifshitz-van der Waals forces and less specific hydrogen bonds between SSS and microorganism, which was been confirmed via both single bacterial force spectroscopy measurement and molecular dynamics simulation. Compared with the traditional slippery lubricant-infused porous surface (SLIPS), the SSS exhibited a better robust mechanical stability than that of the SLIPS. In addition, our study provides a valuable method to fabricated the SSS with reliable underwater-transmittance and antifouling properties, which is promised for the applications for the antifouling of marine optical instruments.


Assuntos
Incrustação Biológica , Bactérias , Incrustação Biológica/prevenção & controle , Dimetilpolisiloxanos , Porosidade , Propriedades de Superfície
8.
ACS Appl Mater Interfaces ; 14(21): 24840-24849, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35584034

RESUMO

Patterning elastomers is an essential process for the application of elastomers to stretchable bioelectric devices. In general, replication of a mold and laser ablation are used for patterning elastomers. However, these methods are inefficient and time consuming due to complex patterning procedures and a heat-induced curing mechanism. In this work, we developed a photopatternable elastomer called thiol-ene cross-linked poly(dimethylsiloxane) (TC-PDMS). TC-PDMS showed high-resolution patternability (∼100 µm) through a direct patterning process. It also had high stretchability (∼140%) and low Young's modulus (∼2.9 MPa) similar to conventional PDMS. To demonstrate its practicability in stretchable bioelectric devices, TC-PDMS was applied to a passivation layer of an intrinsically stretchable organic electrochemical transistor (OECT), which showed a low leakage current (∼20 µA) and a high transconductance (0.432 mS) at high strain (60%). The stretchable OECT was able to record electrocardiographic (ECG) signals from human skin, and the measured ECG signals exhibited a high signal-to-noise ratio of 12.2 dB.


Assuntos
Dimetilpolisiloxanos , Elastômeros , Módulo de Elasticidade , Humanos , Pele
9.
ACS Sens ; 7(5): 1467-1475, 2022 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-35537189

RESUMO

This work presents an imprinted polymer-based thermal biomimetic sensor for the detection of Escherichia coli. A novel and facile bacteria imprinting protocol for polydimethylsiloxane (PDMS) films was investigated, and these receptor layers were functionalized with graphene oxide (GO) in order to improve the overall sensitivity of the sensor. Upon the recognition and binding of the target to the densely imprinted polymers, a concentration-dependent measurable change in temperature was observed. The limit of detection attained for the sensor employing PDMS-GO imprints was 80 ± 10 CFU/mL, a full order lower than neat PDMS imprints (670 ± 140 CFU/mL), illustrating the beneficial effect of the dopant on the thermo-dynamical properties of the interfacial layer. A parallel benchmarking of the thermal sensor with a commercial impedance analyzer was performed in order to prove the possibility of using the developed PDMS-GO receptors with multiple readout platforms. Moreover, S. aureus, C. sakazakii and an additional E. coli strain were employed as analogue species for the assessment of the selectivity of the device. Finally, because of the potential that this biomimetic platform possesses as a low-cost, rapid, and on-site tool for monitoring E. coli contamination in food safety applications, spiked fruit juice was analyzed as a real sample. Reproducible and sensitive results fulfill the limit requirements of the applicable European microbiological regulation.


Assuntos
Impressão Molecular , Biomimética , Dimetilpolisiloxanos , Escherichia coli , Grafite , Impressão Molecular/métodos , Polímeros/química , Staphylococcus aureus
10.
Int J Mol Sci ; 23(9)2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35563526

RESUMO

Chitosan (CS)/poly(ethylene oxide) (PEO)-based nanofiber mats have attracted particular attention as advanced materials for medical and pharmaceutical applications. In the scope of present studies, solution blow spinning was applied to produce nanofibers from PEO and CS and physicochemical and biopharmaceutical studies were carried out to investigate their potential as wound nanomaterial for skin healing and regeneration. Additional coating with hydrophobic poly(dimethylsiloxane) was applied to favor removal of nanofibers from the wound surface. Unmodified nanofibers displayed highly porous structure with the presence of uniform, randomly aligned nanofibers, in contrast to coated materials in which almost all the free spaces were filled in with poly(dimethylsiloxane). Infrared spectroscopy indicated that solution blow technique did not influence the molecular nature of native polymers. Obtained nanofibers exhibited sufficient wound exudate absorbency, which appears beneficial to moisturize the wound bed during the healing process. Formulations displayed greater tensile strength as compared to commercial hydrofiber-like dressing materials comprised of carboxymethylcellulose sodium or calcium alginate, which points toward their protective function against mechanical stress. Coating with hydrophobic poly(dimethylsiloxane) (applied to favor nanofiber removal from the wound surface) impacted porosity and decreased both mechanical properties and adherence to excised human skin, though the obtained values were comparable to those attained for commercial hydrofiber-like materials. In vitro cytotoxicity and irritancy studies showed biocompatibility and no skin irritant response of nanofibers in contact with a reconstituted three-dimensional human skin model, while scratch assay using human fibroblast cell line HDFa revealed the valuable potential of CS/PEO nanofibers to promote cell migration at an early stage of injury.


Assuntos
Quitosana , Nanofibras , Antibacterianos/química , Quitosana/química , Dimetilpolisiloxanos , Óxido de Etileno , Humanos , Nanofibras/química , Polietilenoglicóis/química
11.
Int J Mol Sci ; 23(9)2022 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-35563610

RESUMO

BACKGROUND: medical device-induced infections affect millions of lives worldwide and innovative preventive strategies are urgently required. Antimicrobial peptides (AMPs) appear as ideal candidates to efficiently functionalize medical devices surfaces and prevent bacterial infections. In this scenario, here, we produced antimicrobial polydimethylsiloxane (PDMS) by loading this polymer with an antimicrobial peptide identified in human apolipoprotein B, r(P)ApoBLPro. METHODS: once obtained loaded PDMS, its structure, anti-infective properties, ability to release the peptide, stability, and biocompatibility were evaluated by FTIR spectroscopy, water contact angle measurements, broth microdilution method, time-killing kinetic assays, quartz crystal microbalance analyses, MTT assays, and scanning electron microscopy analyses. RESULTS: PDMS was loaded with r(P)ApoBLPro peptide which was found to be present not only in the bulk matrix of the polymer but also on its surface. ApoB-derived peptide was found to retain its antimicrobial properties once loaded into PDMS and the antimicrobial material was found to be stable upon storage at 4 °C for a prolonged time interval. A gradual and significant release (70% of the total amount) of the peptide from PDMS was also demonstrated upon 400 min incubation and the antimicrobial material was found to be endowed with anti-adhesive properties and with the ability to prevent biofilm attachment. Furthermore, PDMS loaded with r(P)ApoBLPro peptide was found not to affect the viability of eukaryotic cells. CONCLUSIONS: an easy procedure to functionalize PDMS with r(P)ApoBLPro peptide has been here developed and the obtained functionalized material has been found to be stable, antimicrobial, and biocompatible.


Assuntos
Anti-Infecciosos , Infecções Bacterianas , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Apolipoproteínas B/química , Biofilmes , Dimetilpolisiloxanos/química , Humanos , Peptídeos/farmacologia , Polímeros/farmacologia
12.
BMJ Case Rep ; 15(5)2022 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-35618340

RESUMO

Bariatric surgery is an effective treatment for obesity and obesity-related complications. Weight regain after surgery plagues all methods of bariatric procedures including the minigastric bypass. The use of a 'silastic ring' around the gastric pouch has been shown to reduce weight regain. We present here a very rare complication of silastic ring use, in which a loop of small bowel had herniated through the ring and produced a closed loop small bowel obstruction. The patient was successfully treated with an emergency laparotomy to resect the silastic ring and release the herniated bowel. This case highlights the hernia risk that silastic rings pose and cautions careful consideration before their use.


Assuntos
Cirurgia Bariátrica , Derivação Gástrica , Obstrução Intestinal , Obesidade Mórbida , Cirurgia Bariátrica/efeitos adversos , Dimetilpolisiloxanos , Derivação Gástrica/efeitos adversos , Derivação Gástrica/métodos , Hérnia/diagnóstico por imagem , Hérnia/etiologia , Humanos , Obstrução Intestinal/diagnóstico por imagem , Obstrução Intestinal/etiologia , Obstrução Intestinal/cirurgia , Obesidade/complicações , Obesidade/cirurgia , Obesidade Mórbida/complicações , Obesidade Mórbida/cirurgia , Ganho de Peso
13.
J Colloid Interface Sci ; 622: 419-430, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35525145

RESUMO

Bacterial infections related to medical devices can cause severe problems, whose solution requires in-depth understanding of the interactions between bacteria and surfaces. This work investigates the influence of surface physicochemistry on bacterial attachment and detachment under flow through both empirical and simulation studies. We employed polydimethylsiloxane (PDMS) substrates having different degrees of crosslinking as the model material and the extended Derjaguin - Landau - Verwey - Overbeek model as the simulation method. Experimentally, the different PDMS materials led to similar numbers of attached bacteria, which can be rationalized by the identical energy barriers simulated between bacteria and the different materials. However, different numbers of residual bacteria after detachment were observed, which was suggested by simulation that the detachment process is determined by the interfacial physicochemistry rather than the mechanical property of a material. This finding is further supported by analyzing the bacteria detachment from PDMS substrates from which non-crosslinked polymer chains had been removed: similar numbers of residual bacteria were found on the extracted PDMS substrates. The knowledge gained in this work can facilitate the projection of bacterial colonization on a given surface.


Assuntos
Bactérias , Dimetilpolisiloxanos , Aderência Bacteriana , Simulação por Computador , Dimetilpolisiloxanos/química , Propriedades de Superfície
14.
Int J Mol Sci ; 23(10)2022 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-35628204

RESUMO

Protein entrapment has multiple applications in enzymatic hydrolysis, drug delivery, etc. Here, we report the studies that successfully utilized the Box-Behnken design to model and optimize the parameters of ß-galactosidase entrapment in sol-gel-derived silica composites. We have also demonstrated the influence of polymer-polydimethylsiloxane as a composite modifying agent on the activity of entrapped enzymes. We have determined how different sol-gel process parameters influence the activity of entrapped enzymes. The highest impact on ß-galactosidase activity was exerted by the water:tetramethoxysilane ratio, followed by polydimethylsiloxane content. Optimized synthesis parameters have been utilized to obtain a composite with maximum ß-galactosidase activity. Performed porosity studies have shown that the addition of polydimethylsiloxane increased the pore diameter. Microscopy studies demonstrated that polydimethylsiloxane-modified composites are softer and less rough. Studies of ß-galactosidase activity using the o-NPG test showed statistically significant shifts in the enzyme temperature and pH profiles compared to the soluble form. An improvement in the reusability of the enzyme and a significant increase in the thermal stability was also observed. When lactose was used, a strong correlation was observed between the substrate concentration and the type of the catalyzed reaction. Moreover, we have demonstrated that the yields and rates of both lactose hydrolysis and galactooligosaccharides formation were correlated with reaction temperature and with the presence of polydimethylsiloxane. All these findings provide the opportunity for industrial use of optimized PDMS-modified silica composites in lactose elimination from dairy products, e.g., milk or whey.


Assuntos
Lactose , Dióxido de Silício , Dimetilpolisiloxanos , Lactose/química , Sílica Gel , Soro do Leite/metabolismo , beta-Galactosidase/metabolismo
15.
Proc Natl Acad Sci U S A ; 119(20): e2122468119, 2022 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-35549547

RESUMO

Due to their augmented properties, biomimetic polymer/lipid hybrid compartments are a promising substitute for natural liposomes in multiple applications, but the protein-free fusion of those semisynthetic membranes is unexplored to date. Here, we study the charge-mediated fusion of hybrid vesicles composed of poly(dimethylsiloxane)-graft-poly(ethylene oxide) and different lipids and analyze the process by size distribution and the mixing of membrane species at µm and nano scales. Remarkably, the membrane mixing of oppositely charged hybrids surpasses by far the degree in liposomes, which we correlate with properties like membrane disorder, rigidity, and ability of amphiphiles for flip-flop. Furthermore, we employ the integration of two respiratory proteins as a functional content mixing assay for different membrane compositions. This reveals that fusion is also attainable with neutral and cationic hybrids and that the charge is not the sole determinant of the final adenosine triphosphate synthesis rate, substantiating the importance of reconstitution environment. Finally, we employ this fusion strategy for the delivery of membrane proteins to giant unilamellar vesicles as a way to automate the assembly of synthetic cells.


Assuntos
Dimetilpolisiloxanos , Sistemas de Liberação de Medicamentos , Polietilenoglicóis , Dimetilpolisiloxanos/química , Membranas Artificiais , Fosfolipídeos/química , Polietilenoglicóis/química
16.
Mater Sci Eng C Mater Biol Appl ; 135: 112687, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35581080

RESUMO

Conventionally, macro-textured surfaces comprising several hundred micrometer-sized patterns are used to minimize silicone-based breast implant complications, including capsular contracture. However, because of the recent cases of breast implant-associated anaplastic large cell lymphoma from macro-textured implants, there is a strong demand for nano- or micro-textured silicone implants with dimensions smaller than sub-micrometers. Herein, we propose a simple and cost-effective topographical surface modification strategy for silicone-based implants. Several hundred nanometer to sub-micrometer wide groove-type micro-textures were fabricated on a polydimethylsiloxane surface using electrospun polyvinylpyrrolidone fibers as a sacrificial template. The aligned and randomly oriented micro-textures were prepared by controlling the electrospun fiber orientation. In vitro experiments demonstrated that the micro-textured polydimethylsiloxane was cytocompatible and suppressed differentiation of fibroblasts into myofibroblasts. Importantly, the aligned micro-texture promoted the polarization of macrophages into the anti-inflammatory M2 phenotype. Long-term in vivo studies established that the micro-textures potently suppressed various factors affecting foreign body reactions by downregulating profibrotic cytokine gene expression and reducing the fibroblast and myofibroblast counts, the cells playing important roles in the immune response. Thus, the thickness and collagen density of fibrous capsules were decreased, demonstrating that the micro-textured surface effectively inhibited capsular contracture. Although the aligned micro-textures contributed to the polarization of macrophages to the M2 phenotype both in vitro and in vivo, foreign body reaction by both the aligned and randomly oriented micro-textures are similar.


Assuntos
Implantes de Mama , Contratura , Dimetilpolisiloxanos , Fibrose , Humanos , Silicones , Propriedades de Superfície
17.
Anal Bioanal Chem ; 414(17): 4987-4998, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35608670

RESUMO

Headspace solid-phase micro-extraction (SPME) is a promising technique for the characterisation and profiling of gunshot exhausts in spent cartridge casings, especially for health and environmental risk assessments, as well as forensic purposes. To date, however, no comprehensive investigation has been carried out to objectively assess the kinds of compound released during a discharge that can be recovered by this approach, the selectivity of the main commercially available fibres, and their relative performances for the analysis of gunshot exhausts and the discrimination of different ammunition types. This study aimed to fill this gap. Gunshot exhausts in spent cartridge casings from four different ammunition types were analysed by GC-MS, after extraction with four different commercial fibres: 100 µm polydimethylsiloxane (PDMS), 85 µm polyacrylate (PA), 65 µm polydimethylsiloxane/divinylbenzene (DVB), and 85 µm carboxen/polydimethylsiloxane (CAR). Results showed that, overall, a total of 120 analytes could be observed across the cartridges, but the different tested fibres also displayed distinct performances, which were, to some extent, complementary for the characterisation of gunshot exhausts. DVB, in particular, recovered the most compounds simultaneously. On the other hand, the observed variability between measurements was also high, making it a poor candidate for (semi-)quantitative applications (e.g. estimation of time since discharge and/or source profiling). In this regard, PA demonstrated the highest potential for broad use and implementation in multi-purpose methods.


Assuntos
Dimetilpolisiloxanos , Microextração em Fase Sólida , Cromatografia Gasosa-Espectrometria de Massas/métodos , Microextração em Fase Sólida/métodos
18.
Sensors (Basel) ; 22(7)2022 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-35408355

RESUMO

Stretchable strain sensors are capable of acquiring data when in contact with human skin or equipment and are widely used in wearable applications. Most strain sensors have tensile properties of less than 20% and have limitations regarding body motion linkage, complex sensor structure, and motion nonreliability. To address these problems, we developed a high tension and high sensitivity sensor with a gauge factor over 40 and tensile stress about 50%. Polydimethylsiloxane (PDMS) was selected as the flexible substrate to ensure tensile strength, and polyaniline (PANI) was used to measure the resistance changes in the sensor. In particular, problems regarding poor uniformity of PANI on PDMS were resolved by surface treatment of the PDMS, wherein PANI polymerization was performed sequentially after forming a self-assembled monolayer (SAM) on the PDMS substrate. O2 plasma and (3-aminopropyl)triethoxysilane were used to form the SAM. It is expected that this sensor can obtain stable characteristics even under high tensile stress through the evenly formed PANI films on the surface-treated PDMS substrate and may be used in various flexible sensor applications.


Assuntos
Dimetilpolisiloxanos , Compostos de Anilina , Dimetilpolisiloxanos/química , Humanos , Polimerização , Propilaminas , Silanos
19.
Int J Mol Sci ; 23(7)2022 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-35409042

RESUMO

Hydrophobic fibrous slippery liquid-infused porous surfaces (SLIPS) were fabricated by electrospinning polydimethylsiloxane (PDMS) and polystyrene (PS) as a carrier polymer on plasma-treated polyethylene (PE) and polyurethane (PU) substrates. Subsequent infusion of blackseed oil (BSO) into the porous structures was applied for the preparation of the SLIPS. SLIPS with infused lubricants can act as a repellency layer and play an important role in the prevention of biofilm formation. The effect of polymer solutions used in the electrospinning process was investigated to obtain well-defined hydrophobic fibrous structures. The surface properties were analyzed through various optical, macroscopic and spectroscopic techniques. A comprehensive investigation of the surface chemistry, surface morphology/topography, and mechanical properties was carried out on selected samples at optimized conditions. The electrospun fibers prepared using a mixture of PDMS/PS in the ratio of 1:1:10 (g/g/mL) using tetrahydrofuran (THF) solvent showed the best results in terms of fiber uniformity. The subsequent infusion of BSO into the fabricated PDMS/PS fiber mats exhibited slippery behavior regarding water droplets. Moreover, prepared SLIPS exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli bacterium strains.


Assuntos
Dimetilpolisiloxanos , Poliestirenos , Escherichia coli , Polímeros/química , Porosidade
20.
J Biomed Opt ; 27(8)2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35380031

RESUMO

SIGNIFICANCE: Optical and acoustic imaging techniques enable noninvasive visualisation of structural and functional properties of tissue. The quantification of measurements, however, remains challenging due to the inverse problems that must be solved. Emerging data-driven approaches are promising, but they rely heavily on the presence of high-quality simulations across a range of wavelengths due to the lack of ground truth knowledge of tissue acoustical and optical properties in realistic settings. AIM: To facilitate this process, we present the open-source simulation and image processing for photonics and acoustics (SIMPA) Python toolkit. SIMPA is being developed according to modern software design standards. APPROACH: SIMPA enables the use of computational forward models, data processing algorithms, and digital device twins to simulate realistic images within a single pipeline. SIMPA's module implementations can be seamlessly exchanged as SIMPA abstracts from the concrete implementation of each forward model and builds the simulation pipeline in a modular fashion. Furthermore, SIMPA provides comprehensive libraries of biological structures, such as vessels, as well as optical and acoustic properties and other functionalities for the generation of realistic tissue models. RESULTS: To showcase the capabilities of SIMPA, we show examples in the context of photoacoustic imaging: the diversity of creatable tissue models, the customisability of a simulation pipeline, and the degree of realism of the simulations. CONCLUSIONS: SIMPA is an open-source toolkit that can be used to simulate optical and acoustic imaging modalities. The code is available at: https://github.com/IMSY-DKFZ/simpa, and all of the examples and experiments in this paper can be reproduced using the code available at: https://github.com/IMSY-DKFZ/simpa_paper_experiments.


Assuntos
Óptica e Fotônica , Software , Acústica , Dimetilpolisiloxanos , Processamento de Imagem Assistida por Computador/métodos
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