Bioactive Nanogels Mimicking the Antithrombogenic Nitric Oxide-Release Function of the Endothelium

Nitric oxide (NO) plays a significant role in controlling the physiology and pathophysiology of the body, including the endothelial antiplatelet function and therefore, antithrombogenic property of the blood vessels. This property of NO can be exploited to prevent thrombus formation on artificial surfaces like extracorporeal membrane oxygenators, which when come into contact with blood lead to protein adsorption and thereby platelet activation causing thrombus formation. However, NO is extremely reactive and has a very short biological half-life in blood, so only endogenous generation of NO from the blood contacting material can result into a stable and kinetically controllable local delivery of NO. In this regards, highly hydrophilic bioactive nanogels are presented which can endogenously generate NO in blood plasma from endogenous NO-donors thereby maintaining a physiological NO flux. It is shown that NO releasing nanogels could initiate cGMP-dependent protein kinase signaling followed by phosphorylation of vasodilator-stimulated phosphoprotein in platelets. This prevents platelet activation and aggregation even in presence of highly potent platelet activators like thrombin, adenosine 5′-diphosphate, and U46619 (thromboxane A2 mimetic).     

Cleanroom-Free Fabrication of Microneedles for Multimodal Drug Delivery

Microneedles have recently emerged as a powerful tool for minimally invasive drug delivery and body fluid sampling. To date, high-resolution fabrication of microneedle arrays (MNAs) is mostly achieved by the utilization of sophisticated facilities and expertise. Particularly, hollow microneedles have usually been manufactured in cleanrooms out of silicon, resin, or metallic materials. Such strategies do not support the fabrication of microneedles from biocompatible/biodegradable materials and limit the capability of multimodal drug delivery for the controlled release of different therapeutics through a combination of injection and sustained diffusion. This study implements low-cost 3D printers to fabricate relatively large needle arrays, followed by repeatable shrink-molding of hydrogels to form high-resolution molds for solid and hollow MNAs with controllable sizes. The developed strategy further enables modulating surface topography of MNAs to tailor their surface area and instantaneous wettability for controllable drug delivery and body fluid sampling. Hybrid gelatin methacryloyl (GelMA)/polyethylene glycol diacrylate (PEGDA) MNAs are fabricated using the developed strategy that can easily penetrate the skin and enable multimodal drug delivery. The proposed method holds promise for affordable, controllable, and scalable fabrication of MNAs by researchers and clinicians for controlled spatiotemporal administration of therapeutics and sample collection.     

Design of a high-throughput device for screening surface modification protocols

The development of new high performance, ultra-thin organic coatings requires a strategy that has to consider a large number of surface treatment variables such as binding moieties, substrate, and adsorption conditions (e.g. temperature, solvent, concentration, pH, salt). The optimization of the latter is often the bottleneck of the entire development process and restricts the number of parameters that can be tested with acceptable effort. Here we present a screening platform for the efficient, parallel testing of various surface modification protocols, based on an array of 70 wells for individual adsorption experiments with a volume of 20 μL each (SuMo device). The device performance was validated using the copolymer poly(l-lysine)-grafted-poly(ethylene glycol) (PLL-g-PEG) that adsorbs on negatively charged surfaces, rendering them non-fouling in contact with proteins such as fibrinogen. The latter functionality was tested by a second adsorption step of FITC-labelled fibrinogen; polymer and protein thickness values, measured by spectroscopic ellipsometry were used as a measure for the quality of the polymer adlayer. The results obtained are in excellent agreement with traditional coating methods using single chips for each parameter set. A further improvement in the efficiency of the surface modification experiments resulted from the use of a fluorescence read out of the fibrinogen adsorption. Measurements with a microarray scanner proved to be very fast providing uniform fluorescence images with low bleaching rate and high detection sensitivity. The results of the fluorescence readout correlated with the ellipsometry data with a lower limit of detection of ca. 2% of a saturated layer for both techniques. The readout data of the SuMo device were further compared with the quantitative results from in situ optical waveguide lightmode spectroscopy (OWLS) and successfully validated by testing the dependence of fibrinogen coverage as a function of fibrinogen solution concentration. Finally, to demonstrate its application feasibility, the array device was applied to study the polymeric surface layer stability under a range of harsh conditions (14 > pH > 1, ionic strength up to 5.3 M NaCl).     

Improving the Mechanical Properties of Poly Methyl Methacrylate Nanocomposites for Dentistry Applications Reinforced with Different Nanoparticles

Properties of poly methyl methacrylate are improved using different nanoparticles for denture applications and the best combination is selected using multi-criteria decision-making methods. For these purposes, poly methyl methacrylate is melt compounded with TiO₂, SiO₂, and Al₂O₃ nanoparticles and then injection molded. The results of mechanical tests revealed that by addition of TiO₂ and SiO₂, the impact strengths of poly methyl methacrylate were increased 229 and 62%, respectively. Also, the results indicated a significant improvement in Young’s modulus and hardness. The implementation of multi-criteria decision-making methods illustrated that TiO₂ nanoparticles are the best candidate for improving the properties of poly methyl methacrylate for dental applications.     

Multi-objective Antenna Selection in a Full Duplex Base Station

Wireless Personal Communications - The use of full-duplex (FD) communication systems is a new way to increase spectral efficiency. For this reason, it has received serious attention in the new...     

Predicting stock returns of Tehran exchange using LSTM neural network and feature engineering technique

Multimedia Tools and Applications - Prediction is defined as the expression of events that will occur in the future, before they occur, based on scientific and logical principles and rules. Due to...     

An intelligent IoT-based positioning system for theme parks

The Journal of Supercomputing - With the advent of the Internet of Things (IoT) and ubiquitous presence of sensor nodes, positioning technologies have become a topic of interest among researchers....     

Research on the human heat transfer model of Chinese pilots and experimental verification of model correctness

Neural Computing and Applications - A three-dimensional human heat transfer model has been improved based on Chinese pilots’ anthropometric data. The temperature distribution of pilots can be...