Extracellular Matrix-Based Conductive Composites for Myocardial Tissue Regeneration.

Myocardial tissue engineering strategies such as fabrication of cardiac patches for tissue regeneration offer various solutions for the loss of function developed due to myocardial infarction. Here, we combined the hybrid structure (previously obtained and combined decellularized myocardium grafts with poly(glycerol-sebacate) polymer) with multiwalled carbon nanotubes (MWCNTs) to provide the essential characteristics for cardiac tissue regeneration. MWCNTs were doped in the cross-linked structure, and the conductivity and Young's modulus of the composite elastomer were found as 5 × 10-3 ± 1 × 10-3 S/m and 374 ± 75.8 kPa, respectively. The cell-material interaction was evaluated, and composite structures supported cell adhesion and showed no cytotoxic effect.

Experimental Investigation of Microfluidic Device for Platelet Activation.

OBJECTIVE: Wound healing is accelerated when Platelet Rich Plasma is activated and growth factors are released. In this study, it was aimed to stimulate platelets without using chemical stimulants. METHOD: Two types of mechanical platelet activation methods have been proposed in this study. The first one is a microfluidic chip developed with the shear-induced platelet activation approach. The second one is a piezo-based ultrasound-assisted device which provides platelet activation by stimulating with an ultrasonic wave (0.55 and 1.1 MHz). Three different microfluidic chip designs were worked out to determine the optimal shear stress characteristics; 8-nodes (2789 µs, 288 shear pulses, and 98.3 dyne/cm2), 40-nodes (2765 µs, 1440 shear pulses, and 95.5 dyne/cm2) and pillar-shaped (1030 µs, 1656 shear pulses, and 48.1 dyne/cm2). RESULTS: The highest platelet activation rate (72.7%) was obtained from the chips with 8-nodes. In the ultrasound-assisted device, 32.4% activation rate was obtained from ultrasound waves with 0.55 MHz frequency and 10 Vp-p amplitude. These activation rates, determined by CD62P (P-Selectin) expression, are significantly higher than spontaneous activation of intact platelets (8.5%). In addition, the gradual increase in activation of stimulated platelets with incubation at room temperature showed that activation continued after stimulation. CONCLUSION: The results showed that these microfluidic devices can be used for platelet activation to enhance the effect of PRP treatment and might reduce adverse immune reactions that may happened due to the use of exogenous activator substances. SIGNIFICANCE: Fast-response, low-cost, easy-to-use and controllable biomedical device have been developed for PRP applications.

Fabrication and characterization of carbon aerogel/poly(glycerol-sebacate) patches for cardiac tissue engineering.

Cardiovascular diseases (CVDs) are responsible for the major number of deaths around the world. Among these is heart failure after myocardial infarction whose latest therapeutic methods are limited to slowing the end-state progression. Numerous strategies have been developed to meet the increased demand for therapies regarding CVDs. This study aimed to establish a novel electrically conductive elastomer-based composite and assess its potential as a cardiac patch for myocardial tissue engineering. The electrically conductive carbon aerogels (CAs) used in this study were derived from waste paper as a cost-effective carbon source and they were combined with the biodegradable poly(glycerol-sebacate) (PGS) elastomer to obtain an electrically conductive cardiac patch material. To the best of our knowledge, this is the first report about the conductive composites obtained by the incorporation of CAs into PGS (CA-PGS). In this context, the incorporation of the CAs into the polymeric matrix significantly improved the elastic modulus (from 0.912 MPa for the pure PGS elastomer to 0.366 MPa for the CA-PGS) and the deformability (from 0.792 MPa for the pure PGS to 0.566 MPa for CA-PGS). Overall, the mechanical properties of the obtained structures were observed similar to the native myocardium. Furthermore, the addition of CAs made the obtained structures electrically conductive with a conductivity value of 65 × 10-3S m-1which falls within the range previously recorded for human myocardium. Thein vitrocytotoxicity assay with L929 murine fibroblast cells revealed that the CA-PGS composite did not have cytotoxic characteristics. On the other hand, the studies conducted with H9C2 rat cardiac myoblasts revealed that final structures were suitable for MTE applications according to the successes in cell adhesion, cell proliferation, and cell behavior.

Microwave-Assisted Synthesis of Stretchable and Transparent Poly(Ethyleneglycol-Sebacate) Elastomers with Autonomous Self-Healing and Capacitive Properties.

Introducing functional synthetic biomaterials to the literature became quite essential in biomedical technologies. For the growth of novel biomedical engineering approaches, progressive functional properties as well as the robustness of the manufacturing processes are essential. By using acid-induced epoxide ring-opening polymerizations through catalysts, a wide variety of biodegradable and functionalized biomaterials can be synthesized. Sebacic acid (SA) and poly(ethylene glycol) diglycidyl ether (PEGDGE) are amongst the FDA-approved biocompatible materials. In this study, we focused on the rapid synthesis of caffeine-catalyzed self-healable elastomer via a facile microwave-assisted synthesis route. The elastomer prepared can be used in various applications, including tactile sensors, wearable electronics, and soft robotics. SA and PEGDGE were catalyzed in the presence of caffeine under microwave irradiation followed by crosslinking in vacuo, yielding an elastomeric material. The chemical characterizations of the obtained elastomer were carried out. The resulting material is transparent, highly stretchable, and has capacitive and self-healing properties even at room temperature. The material developed can be easily applied for the aforementioned applications.

A Flexible and Low-Cost Tactile Sensor Produced by Screen Printing of Carbon Black/PVA Composite on Cellulose Paper.

This study presents the design and fabrication of a flexible tactile sensor printed on a cellulose paper substrate using a carbon black (CB) - filled polyvinyl alcohol (PVA) polymer matrix as ink material. In the design, electrodes are obtained by screen printing of CB/PVA composite on dielectric cellulose paper. The screen-printing method is preferred for fabrication because of its simplicity and low manufacturing cost. The tactile sensor is formed by overlapping two ink-printed sheets. Electrical properties are investigated under compressive and tensile strains. The results indicate that the tactile sensor configuration and materials can be used for piezoresistive, capacitive, and also impedance sensors. The same tactile sensor structure is also examined using a commercial carbon-based ink for performance comparison. The comparative study indicates that CB/PVA ink screen-printed on paper demonstrates superior sensitivity for capacitive sensing with low hysteresis, as well as low response and recovery times. The piezoresistive-sensing properties of CB/PVA on cellulose paper show a gauge factor (GF) of 10.68, which is also very promising when conventional metal strain gauges are considered. CB/PVA screen-printed on cellulose paper features impedance-sensing properties and is also sensitive to the measurement frequency. Therefore, the response type of the sensor can be altered with the frequency.

Synthesis of Conductive Carbon Aerogels Decorated with ß-Tricalcium Phosphate Nanocrystallites.

There has been substantial interest in research aimed at conductive carbon-based supports since the discovery that the electrical stimulus can have dramatic effect on cell behavior. Among these carbon-aerogels decorated with biocompatible polymers were suggested as future materials for tissue engineering. However, high reaction temperatures required for the synthesis of the aerogels tend to impair the stability of the polymeric networks. Herein, we report a synthetic route towards carbon-aerogel scaffolds decorated with biocompatible ceramic nanoparticles of tricalcium phosphate. The composites can be prepared at temperature as high as 1100 °C without significant effect on the morphology of the composite which is comparable with the original aerogel framework. Although the conductivity of the composites tends to decrease with the increasing ceramic content the measured conductivity values are similar to those previously reported on polymer-functionalized carbon-aerogels. The cell culture study revealed that the developed constructs support cell proliferation and provide good cell attachment suggesting them as potentially good candidates for tissue-engineering applications.

Identification of Circulating Tumor Cells Using Plasmonic Resonance Effect: Lab-on-a-Chip Analysis and Modelling.

Circulating tumor cells are widely used as biomarkers of cancer. Although early detection of these cells is vital for diagnosis and prognosis of deadly cancer, it is still a challenging issue due to the complex matrix of blood and their low presence in the bloodstream. In the present study, we propose a micro-channeled lab-on-a-chip system using two distinct methods based upon dielectrophoretic force and electrical properties of cells to increase the cell detection capability and identification efficiency and accuracy. The dielectric properties of cells contribute to the difference between negatively charged residues on the cell surface. Firstly, the dielectrophoretic force is used to separate background cells; then, the proposed high-accuracy identification method is used to better examine and study the unidentified cells. In the next phase, by amplification of the current of the unidentified cells flowing through the nanoparticle plasmonic resonance effects, the microfluidics output efficiency is significantly improved. As a result, highly accurate cell identification is achieved by taking advantage of the nanoparticle plasmonic properties. Overall, nanoparticle scattering in the plasmonic resonance condition, as well as their plasmonic hybridization, can improve output signal-to-noise ratio.

Self-terminating growth of platinum films by electrochemical deposition.

A self-terminating rapid electrodeposition process for controlled growth of platinum (Pt) monolayer films from a K(2)PtCl(4)-NaCl electrolyte has been developed that is tantamount to wet atomic layer deposition. Despite the deposition overpotential being in excess of 1 volt, Pt deposition was quenched at potentials just negative of proton reduction by an alteration of the double-layer structure induced by a saturated surface coverage of underpotential deposited H (H(upd)). The surface was reactivated for further Pt deposition by stepping the potential to more positive values, where H(upd) is oxidized and fresh sites for the adsorption of PtCl(4)(2-) become available. Periodic pulsing of the potential enables sequential deposition of two-dimensional Pt layers to fabricate films of desired thickness, relevant to a range of advanced technologies.