Effect of Microwave Treatment on Biophysical and Surface Properties of Polyethylene Terephthalate (PET) for Blood Contact Applications

Bio-piezoelectricity: fundamentals and applications in tissue engineering and regenerative medicine

In recent years, smart materials have piqued the interest of scientists and physicians in the biomedical community owing to their ability to modify their properties in response to an external stimulation or changes in their surroundings. Biocompatible piezoelectric materials are an interesting group of smart materials due to their ability to produce electrical charges without an external power source. Electric signals produced by piezoelectric scaffolds can renew and regenerate tissues through special pathways like that found in the extracellular matrix. This review summarizes the piezoelectric phenomenon, piezoelectric effects generated within biological tissues, piezoelectric biomaterials, and their applications in tissue engineering and their use as biosensors.

Tissue engineering and 3D printing of bioartificial pancreas for regenerative medicine in diabetes

Diabetes is a severe chronic disease worldwide. In various types of diabetes, the pancreatic beta cells fail to secrete sufficient insulin, at some point, to regulate blood glucose levels. Therefore, the replacement of dysfunctional pancreas, islets of Langerhans, or even the insulin-secreting beta cells facilitates physiological regulation of blood glucose levels. However, the current lack of sufficient donor human islets for cell replacement therapy precludes a routine and absolute cure for most of the existing diabetes cases globally. It is envisioned that tissue engineering of a bioartificial pancreas will revolutionize regenerative medicine and the treatment of diabetes. In this review, we discuss the anatomy and physiology of the pancreas, and identify the clinical considerations for engineering a bioartificial pancreas. Subsequently, we dissect the bioengineering problem based on the design of the device, the biomaterial used, and the cells involved. Last but not least, we highlight current tissue engineering challenges and explore potential directions for future work.

Dielectric properties and in vitro hemocompatibility of Nd:YAG laser-irradiated polyethylene terephthalate

Surface properties and morphology of the biomaterial play an essential role in the polymer-material interaction. In this work, laser surface modification of polyethylene terephthalate as a polymer with distinguished mechanical properties was carried out using (neodymium-doped yttrium aluminum garnet) Nd:YAG laser (1.064 µm) with different output power (0.3, 3, and 6 W). The structural, surface, and dielectric properties of PET before and after laser irradiation have been studied using attenuation total reflection-Fourier transform infrared (ATR-FTIR), dielectric spectroscopy (DS), scanning electron microscope (SEM), and contact angle measurements. Moreover, the anticoagulant properties of the laser-irradiated PET was determined through measuring the prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR). In vitro platelet adhesion test was used to assess the platelets adhered to the surface of the samples; in addition to hematological study. It was found that contact angle (θ) measurements of laser-irradiated PET samples decreased compared to the unirradiated PET. The irradiated samples at 0.3 W have the lowest contact angle which is a clear indication that surface treatment with Nd:YAG laser brought about improving the wettability of the polymer. From the dielectric measurements, both values of permittivity and dielectric loss decrease by increasing the laser power. The electrical conductivity decreases with increasing laser power, but still in the same order 10-14 S/cm. The decrease in electrical conductivity σ may be due to the cross-linking of the polymeric matrix which led to a decrease in the total polarity and consequently decrease in electrical conductivity. The magnitude of σ obtained is highly recommended to be used for insulator purposes in addition to the main purpose that is blood contact.

Preparation and characterization of polyethylene terephthalate-chamomile oil blends with enhanced hydrophilicity and anticoagulant properties

New blend films based on polyethylene terephthalate (PET) with different concentrations (50, 100 and 200 µL) of chamomile oil (CAO) were prepared. The effect of oil on the dielectric properties, structural and surface properties of PET was studied. The wettability of the blend films was evaluated by contact angle measurements. In vitro platelet adhesion on the surface and coagulation assessment were conducted to evaluate the behavior of the new blends for blood contact applications. Results of the study indicate that the wettability of PET-CAO blends up to 100 µL has been enhanced relative to the pure PET as indicated by the decrease in contact angle measurements. The attenuation total reflection-Fourier transform infrared spectra of the blends confirmed the presence of chamomile oil in the polymer matrix and suggested the presence of interaction between them. The permittivity ε' values decreased by increasing oil content upto 100 µL. On the other hand, the values of dielectric loss ε″ were found to increase by increasing oil content to 100 µL after which it decreased. The delay in partial thromboplastin time (PTT) of the blood would validate the anti-coagulant property of PET-CAO blends. The results demonstrated that the PET-CAO blends with concentration of 100 µL could be considered as a promising candidate material in blood contact application.