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In this study, graphene‐loaded electrospun recycled poly(ethylene terephthalate) (rPET) nanofibrous mats were produced and characterized morphologically, spectrally, mechanically and thermally. Particularly, the effects of graphene nanoplatelets (GNP) and multilayer graphene (GML) in improving the thermal conductivity and heat dissipation abilities of rPET‐based composite nanofibers were investigated. The morphological analyzes pointed out that 1% graphene loading led to smooth nanofibers while 5 and 10% of GNP‐loading resulted in coarser nanofibers with rougher surfaces and agglomerations. The differential scanning calorimetry results pointed out that the crystallization temperature increased with increasing graphene content as a result of the pronounced nucleation effect. The thermogravimetric analysis demonstrated an improvement in the thermal stability of the composite nanofibers. The thermal conductivity coefficients increased to 25.422 W/mK‐35.842 W/mK for rPET/GNP nanofibers and up to 62.669 W/mK for rPET/GML nanofibers, compared to that of 12.753 W/mK for neat rPET nanofibers which correspond to an increase between 99 and 391%. Heat dissipation capability of the graphene‐loaded composite nanofibers was illustrated with infrared thermography data, displaying an increase in the average surface temperature of the nanofibrous mats between 2 and 19°C at 30 s of heating. The results suggest the use of the graphene‐loaded rPET composite nanofibers as textile materials for thermoregulating applications. Highlights: Recycled poly(ethylene terephthalate)/graphene composite nanofibers are electrospun.Thermal conductivity of graphene‐loaded nanofibers increases by up to 391%.Graphene loading in nanofibers leads to faster and more uniform heat dissipation.Mechanical properties of composite nanofibers improve.Value‐added recycled polyester materials for thermal management are foreseen. [ABSTRACT FROM AUTHOR]

Combining various carbon nanofillers with different dimensions can lead to a synergistic effect through the formation of an efficient conductive network. Hybrid polyurethane (PU) nanocomposites containing multi‐walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) were fabricated to study experimental and theoretical aspects of thermal conductivity (TC) enhancement. The optimization of hybrid nanofillers combinations was done to synergically enhance the TC using various types of graphene, nanofillers concentrations and ratios. A synergistic thermal conductivity improvement with MWCNTs and GNPs was confirmed at low nanofillers contents. The TC of hybrid nanocomposite at 0.25 wt% is approximately equivalent to the TC of individual nanofillers at 0.75 wt%. An analytical model for the effective thermal conductivity of single and hybrid nanocomposites was considered with variables of volume fraction, interfacial thermal resistance, straightness of the nanofillers and the percolation effect, in which the predictions of the modified models agreed with the experimental results. [ABSTRACT FROM AUTHOR]

Biosensors are analytical tools used for the analysis of biomaterial samples and provide an understanding about the biocomposition, structure, and function of biomolecules and/or biomechanisms by converting the biological response into an electrical and/or optical signal. In particular, with the rise in antibiotic resistance amongst pathogenic bacteria, the study of antibiotic activity and transport across cell membranes in the field of biosensors has been gaining widespread importance. Herein, for the rapid and label‐free detection of antibiotic permeation across a membrane, a microelectrode integrated microfluidic device is presented. The integrated chip consists of polydimethylsiloxane based microfluidic channels bonded onto microelectrodes on‐glass and enables us to recognize the antibiotic permeation across a membrane into the model membranes based on electrical impedance measurement, while also allowing optical monitoring. Impedance testing is label free and therefore allows the detection of both fluorescent and non‐fluorescent antibiotics. As a model membrane, Giant Unilamellar Vesicles (GUVs) are used and impedance measurements were performed by a precision inductance, capacitance, and resistance metre. The measured signal recorded from the device was used to determine the change in concentration inside and outside of the GUVs. We have found that permeation of antibiotic molecules can be easily monitored over time using the proposed integrated device. The results also show a clear difference between bilayer permeation that occurs through the lipidic bilayer and porin‐mediated permeation through the porin channels inserted in the lipid bilayer. [ABSTRACT FROM AUTHOR]

Microchannels fabricated by soft lithography have been favourable in mechanobiological applications for cell culture platforms, especially shear stress studies. Normally, physiological shear stress levels for veins are between 10 and 70 dynes/cm2 (1-7 Pa) and arteries between 1 and 6 dynes/cm2 (0.1-0.7 Pa). In this work, a circular system has been set up by microfluidic pump to mimic physiological environment of monocyte cells for monitoring structural changes at various levels of shear stresses. Shear stresses at 4, 15 and 45 Pa, low, medium and high stresses, respectively, simulated by CFD have been applied on THP-1 cells under different flow rates for 0.5 and 3 h. These cells, which passed through microchannels under these experimental conditions were analysed for their F-actin content by staining with phalloidin and determination of mean fluorescence intensity by fluorescence microscopy and flow cytometry. An increase in THP-1 monocytic cell actin polymerisation is significant in the case of 15 Pa, and slight in the case of 45 Pa shear stress conditions for 0.5 h. This may reflect the structural adaptation of monocytes during a pathological condition such as atherosclerosis. [ABSTRACT FROM AUTHOR]

Dielectrophoresis-based separation of microparticles and living cells are studied with computational and experimental methods. The flow behaviours of particles are modelled and simulated using COMSOL Multiphysics 4.3a software (COMSOL Ltd). Lab-on-a-chip devices having a titanium (Ti) interdigitated electrode layer on a glass substrate and a PDMS microchannel are fabricated to investigate the most effective design for separating particles based on their sizes. Polystyrene particles in different diameters (3.2 and 9.8 μm) are used in the experiments. Green polystyrene particles from red ones are fully separated in a current design. Enrichment of Jurkat cells having 10.1 average diameter in phosphate buffer solution (PBS) medium is achieved. [ABSTRACT FROM AUTHOR]