Hamouda M. Mousa

High-performance glucose biosensor based on chitosan-glucose oxidase immobilized polypyrrole/Nafion/functionalized multi-walled carbon nanotubes bio-nanohybrid film.

A highly electroactive bio-nanohybrid film of polypyrrole (PPy)-Nafion (Nf)-functionalized multi-walled carbon nanotubes (fMWCNTs) nanocomposite was prepared on the glassy carbon electrode (GCE) by a facile one-step electrochemical polymerization technique followed by chitosan-glucose oxidase (CH-GOx) immobilization on its surface to achieve a high-performance glucose biosensor. The as-fabricated nanohybrid composite provides high surface area for GOx immobilization and thus enhances the enzyme-loading efficiency. The structural characterization revealed that the PPy-Nf-fMWCNTs nanocomposite films were uniformly formed on GCE and after GOx immobilization, the surface porosities of the film were decreased due to enzyme encapsulation inside the bio-nanohybrid composite materials. The electrochemical behavior of the fabricated biosensor was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and amperometry measurements. The results indicated an excellent catalytic property of bio-nanohybrid film for glucose detection with improved sensitivity of 2860.3μAmM(-1)cm(-2), the linear range up to 4.7mM (R(2)=0.9992), and a low detection limit of 5μM under a signal/noise (S/N) ratio of 3. Furthermore, the resulting biosensor presented reliable selectivity, better long-term stability, good repeatability, reproducibility, and acceptable measurement of glucose concentration in real serum samples. Thus, this fabricated biosensor provides an efficient and highly sensitive platform for glucose sensing and can open up new avenues for clinical applications.

Development of polyamide-6,6/chitosan electrospun hybrid nanofibrous scaffolds for tissue engineering application

The development of biofunctional and bioactive hybrid polymeric scaffolds seek to mitigate the current challenges in the emerging field of tissue engineering. In this paper, we report the fabrication of a biomimetic and biocompatible nanofibrous scaffolds of polyamide-6,6 (PA-6,6) blended with biopolymer chitosan via one step co-electrospinning technique. Different weight percentage of chitosan 10wt%, 15wt%, and 20wt% were blended with PA-6,6, respectively. The nanocomposite electrospun scaffolds mats enabled to provide the osteophilic environment for cells growth and biomineralization. The morphological and physiochemical properties of the resulted scaffolds were studied using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR) spectroscopy. The improvement in hydrophilicity and mechanical strength of the bio-nanocomposite mesh with 20wt% chitosan embedded, was the desired avenue for adhesion, proliferation and maturation of osteoblast cells as compared to other sample groups and pure PA-6,6 fibrous mat. The biomineralization of the nanocomposite electrospun mats also showed higher ability to nucleate bioactive calcium phosphate (Ca/P) nanoparticles comparing to pristine PA-6,6. Furthermore, the biomimetic nature of scaffolds exhibited the cells viability and regeneration of pre-osteoblast (MC3T3-E1) cells which were assessed via in vitro cell culture test. Collectively, the results suggested that the optimized 20wt% of chitosan supplemented hybrid electrospun fibrous scaffold has significant effect in biomedical field to create osteogenic capabilities for tissue engineering.

Amorphous apatite thin film formation on a biodegradable Mg alloy for bone regeneration: strategy, characterization, biodegradation, and in vitro cell study

Bioactive films with a nanoplate structure were prepared on the surface of a biodegradable AZ31B magnesium (Mg) alloy via anodization in simulated body fluid (SBF) as an electrolyte to control Mg biodegradability and improve surface bioactivity. The effect of the electrolyte temperature and pH values on the formation of the biomimetic film were studied. The electrolyte was set at three different temperatures of 37, 50, and 80 °C, with pH values ranging from 7.4 to 8 for the lower electrolyte temperature and 11.5–12 for the two higher levels of temperature. The apatite films on the different samples were characterized using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FE-SEM), EDS element mapping, X-ray photon spectroscopy (XPS), and FTIR spectroscopy. The water contact angles of the different surfaces were evaluated, moreover, the corrosion behaviors of the different samples were studied using electrochemical potentiodynamic DC, electrochemical impedance spectroscopy (EIS), and immersion tests. The human fetal-osteoblast cell line hFOB 1.19 was used in a cell culture test, and the biological response and cell function were evaluated in vitro using DNA and PCR. The decomposition of the apatite film was affected by the anodization electrolyte temperature, resulting in an amorphous structure. It is observed that the apatite structure has nanoplates at electrolyte temperature (37 to 50) °C and these have a tendency to disappear at 80 °C.

Facile synthesis of TiO 2 /ZrO 2 nanofibers/nitrogen co-doped activated carbon to enhance the desalination and bacterial inactivation via capacitive deionization

Capacitive deionization, as a second generation electrosorption technique to obtain water, is one of the most promising water desalination technologies. Yet; in order to achieve high CDI performance, a well-designed structure of the electrode materials is needed, and is in high demand. Here, a novel composite nitrogen-TiO2/ZrO2 nanofibers incorporated activated carbon (NACTZ) is synthesized for the first time with enhanced desalination efficiency as well as disinfection performance towards brackish water. Nitrogen and TiO2/ZrO2 nanofibers are used as the support of activated carbon to improve its low capacitance and hydrophobicity, which had dramatically limited its adequacy during the CDI process. Importantly, the as-fabricated NACTZ nanocomposite demonstrates enhanced electrochemical performance with significant specific capacitance of 691.78 F g−1, low internal resistance and good cycling stability. In addition, it offers a high capacitive deionization performance of NACTZ yield with electrosorptive capacity of 3.98 mg g−1, and, good antibacterial effects as well. This work will provide an effective solution for developing highly performance and low-cost design for CDI electrode materials.

Composite PCL/HA/simvastatin electrospun nanofiber coating on biodegradable Mg alloy for orthopedic implant application

Recently, magnesium (Mg) and its alloys have attracted more attention because of their biodegradability and fascinating mechanical properties in the medical field. However, their low corrosion resistance and high degradability in the body have a great effect on mechanical stability and cytocompatibility, which hinders its clinical applications. Therefore, here we introduce a bifunctional composite coating composed of polycaprolactone and synthesized hydroxyapatite nanoparticles (HA-NPs) loaded with simvastatin deposited on the AZ31 alloy via electrospinning technique. The synthesized HA-NPs and composite nanofibers layer were characterized using TEM, FE-SEM, FTIR, and XRD to understand the physiochemical properties of the composite nanofibers compared to pristine polymer and bare alloy. Corrosion resistance was evaluated electrochemically using potentiodynamic polarization and EIS measurements, and biodegradability was evaluated in terms of pH and Mg ions release in SBF solution. The as-prepared coating was found to retard the corrosion and increased the osteocompatibility as resulted in cell culture test, a higher cell attachment and proliferation on the implant biointerface, in addition to releasing simvastatin in a controlled platform.

Surface Modification of Magnesium and its Alloys Using Anodization for Orthopedic Implant Application

Magnesium (Mg) as a biodegradable implant brings a revolution in medical field application, especially in bone implant and stent application. Biodegradability of Mg has attracted attentions of researchers to avoid secondary surgery to remove the implant materials after healing process. Various advantages of Mgmake it suitable for medical application such as density, good mechanical properties and biodegradation. However, Mg biodegradability must be controlled to meet tissue-healing period of time because of the high degradation in a physiological environment. Fast corrosion and high alkalinity due to hydrogen release induce tissue inflammation, which limits its clinical applications. Many techniques are applied to the Mg surface to improve surface biocompatibility and control its biodegradability. This chapter focuses on anodization of Mg and its alloys to improve corrosion resistance and biocompatibility for orthopedic application. Mg coating with thin film apatite could enhance the biocompatibility and increase osseointegration formation in the bone fracture side. Evaluation of the required anodized film discussed in the chapter such as chemical composition, biodegradability and biocompatibility.