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BackgroundThe high anatomical complexity of maxillofacial defects caused by tumor can pose a formidable challenge for clinicians when designing an appropriate plan for surgical reconstruction. The intention of this work was to restore the complex anatomy with maximum possible facial functionality and aesthetics of the patient. Based on the medical images generated by computed tomography (CT) scan an optimal therapeutic planning for complex maxillofacial reconstruction was designed. MethodFirstly, the volumetric data sets were carefully evaluated and deeply inspected for accurate diagnosis. Regarding 3D visualization of the CT scan images 3D virtual models for regions of interest were created using a special software of 3D Slicer. Using the resulting 3D virtual models a well-defined virtual surgical planning was generated for multiple surgical procedures, including the osteotomies for bone defects, harvesting autogenous bone graft and creating a customized implant. ResultsThe relevant patient-specific anatomical models for real surgery were translated into the 3D printed physical models, with which the surgeons can rehearse the surgery before coming into the operating room. Precisely defined multiple surgeries for complex maxillofacial reconstruction were proposed in this research that could be transferred to the real-time surgery. ConclusionsThe proposed surgical approach will be beneficial both for the surgeons and patient, including improvement in surgical precision and outcomes, reduction in operating time, as well as understanding surgical procedures and decision making etc.

This study demonstrated the effect of tailored electrospun scaffolds of poly(e-caprolactone) (PCL) and its blending with water-soluble poly(N-vinyl-2-pyrrolidone) (PVP) on dynamics of adhesion and motility of adipose-derived stem cells. We produced PCL and PCL/PVP electrospun scaffolds with circular hole pattern to create variation of fiber density (low and high density area). Scanning electron microscopy revealed that PCL/PVP scaffolds had nano-scale pores on the surface of fibers (nanoporisity) due to PVP extraction. The nanoporosity of PCL/PVP scaffolds showed the increase in water contact angle and the decrease in cell adhesion and proliferation compared to PCL alone scaffolds. PCL alone scaffolds supported cell attachment, exhibiting large spread area and low circularity during 24 h. In addition, the expressions of vinculin, F-actin and phosphorylation of focal adhesion kinase increased in the cells on PCL scaffolds. In order to determine the effect of PCL scaffold with different fiber density on cell motility, we performed single-cell tracking experiments with time-lapse microscopy. In high fiber density area of PCL scaffolds, cells migrated slowly and directionally in a fiber-independent manner. On the other hand, cells in low fiber density moved fast and fiber-dependently, suggesting that large pore size of scaffolds from low fiber density allow cells to migrate or infiltrate inside the scaffolds. Thus, we demonstrated that the nano/microstructural morphological cues of the scaffolds, e.g. nanoporosity of fibers and fiber density and thus porosity, plays a key role in possible targets to regulate cell behaviors, suggesting that well-tailored electrospun scaffolds with desired composition and fiber density are required for a potential means for application in tissue engineering.

Morphological analysis of nanocomposites of polyethylene glycol (PEG) based polyurethanes (TPU) and polyhedral oligomeric silsesquioxanes (POSS) were performed using different techniques (transmission electron microscopy, small and wide X-ray scattering, differential scanning calorimetry) as a function of molecular weight of PEG and the PEG/POSS mole ratio. A strong interdependence in crystallisation behaviour between the two crystals species, i.e. the POSS nanocrystals about 5 nm in size and the crystals in the semicrystalline soft phase of TPU, were found. The mechanical properties (Vickers hardness under load and elastic modulus) determined using recording microindentation techniques at room temperature were significantly improved by POSS for two material formulations. Based on the results of polymethylmethacrylate (PMMA)/silica (SiO2) nanocomposites containing up to 20 wt.-% well-dispersed spherical silica nanoparticles, it has been shown that the indentation fracture mechanics is a straightforward, costand time-effective, powerful tool to analyse the fracture resistance for the novel polymer materials, such as brittle nanostructured polymer-ceramic hybrids. Nepal Journal of Science and Technology Vol. 13, No. 2 (2012) 115-122 DOI: http://dx.doi.org/10.3126/njst.v13i2.7723

We report on the linear viscoelastic properties of a family of entangled linear thermoplastic nonpolar hybrid inorganic−organic polymers: random copolymers of polystyrene (PS) and styryl-based polyhedral oligosilsesquioxane (POSS), R7(Si8O12)(C6H4CHCH2), with R = isobutyl (iBu). A series of styrene−styryl POSS random copolymers with 0, 6, 15, 30, and 50 wt % iBuPOSS were investigated. WAXS and TEM demonstrate that the iBuPOSS disperses in the polymeric matrix at a molecular level. It is observed that the iBuPOSS plays a plasticizer-like effect, yielding a monotonic decrease of the glass-transition temperature with increasing iBuPOSS content. Rheological measurements revealed that linear viscoelastic behavior of the copolymers is also profoundly influenced by the presence of iBuPOSS. The incorporation of iBuPOSS dramatically decreases the rubbery plateau modulus ( ), suggesting a strong dilation effect of isobutyl−POSS on entanglement density. Additionally, the apparent flow activation energy, obtained by...

Based on the results from agglomerate-free PMMA nanocomposites with 10 and 20 wt.-% spherical SiO 2 nanoparticles, it has been shown that indentation fracture mechanics is a straightforward, powerful, cost-effective and time-effective tool for analyzing the fracture resistance of novel polymer materials, such as brittle nanostructured polymer-ceramic hybrids. In contrast to pure PMMA, the R-curve effect, i.e., the enhancement in crack resistance as function of crack size, was not observed in the nanocomposites investigated. Fracture toughness was found to depend on the SiO 2 nanoparticle content, and the maximum value was observed at 10 wt.-%. A significant reduction in fracture toughness occurred at 20 wf.-% SiO 2 nanoparticles, which is associated with a percolation of the bound layers (interfacial layers) around the SiO 2 particles. From DSC data, the thickness of the interfacial polymer layer was estimated to be about 9 nm.

The electrospinning technique was used successfully to fabricate one-dimensional arrays of Au nanoparticles within nanofibers in which the intrinsic nature of the semicrystalline polymer poly(ethylene oxide) (PEO) was employed as a template for the controlled nanoscale organization of nanoparticles. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, UV−visible spectroscopy, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy (TEM) were performed to characterize the resulting electrospun fibers in comparison with pure PEO and PEO/Au nanocomposite before electrospinning. By choosing chloroform as the solvent in this work the observed electrospun fibers were about 400−650 nm in diameter and revealed a well-defined Gaussian distribution. Thermal analysis showed that the dodecanethiol-capped Au nanoparticles preferentially act as heterogeneous nucleating agents for PEO crystallization. Conformational changes occurred by incorporating Au nan...

The mechanical deformation processes of poly(methyl methacrylate)/ montmorillonite nanocomposites and their electrospun fibers were investigated by in situ tensile tests under a transmission electron microscope depending on their morphology. While the polymer nanocomposites deformed in a brittle manner, i.e., crazing, the electrospun polymer nanocomposite fibers deformed through a shear flow process leading to nanonecking due to the strong overlap of stress fields caused by nanopores within the fiber under a uniaxial tensile load. This unique change in deformation behavior provides the possibility that the intrinsic brittle material could be manipulated to be ductile without sacrificing its other attractive properties through a well-controlled electrospinning process.

The synthesis and characterization of POSS containing ABA triblock copolymers is reported. The use of atom transfer radical polymerization (ATRP) enabled the preparation of well-defined model copolymers possessing a rubbery poly(n-butyl acrylate)(pBA) middle segment and glassy poly(3-(3,5,7,9,11,13,15-heptaisobutyl-pentacyclo[9.5.1.13,9.15,15.17,13]-octasiloxane-1-yl)propyl methacrylate(p(MA-POSS)) outer segments. By tuning the relative composition and degree of polymerization (DP) of the two segments, phase separated microstructures were formed in thin films of the copolymer. Specifically, dynamic mechanical analysis and transmission electron microscopy (TEM) observations reveal that for a small molar ratio of p(MA-POSS)/pBA (DP=6/481/6) no evidence of microphase separation is evident while a large ratio (10/201/10) reveals strong microphase separation. Surprisingly, the microphase-separated material exhibits a tensile modulus larger than expected (ca. 2×108 Pa) for a continuous rubber phase for temperatures between a pBA-related Tg and a softening point for the p(MA-POSS)-rich phase. Transmission electron microscopy (TEM) images with selective staining for POSS revealed the formation of a morphology consisting of pBA cylinders in a continuous p(MA-POSS) phase. Thermal studies have revealed the existence of two clear glass transitions in the microphase-separated system with strong physical aging evident for annealing temperatures near the Tg of the higher Tg phase (p(MA-POSS). The observed aging is reflected in wide-angle X-ray scattering as the strengthening of a low-angle POSS-dominated scattering peak, suggesting some level of ordering during physical aging. The Tg of the POSS-rich phase observed in the microphase separated triblock copolymer was nearly 25 °C higher than that of a POSS-homopolymer of the same molecular weight, suggesting a strong confinement-based enhancement of Tg in this system.

Currently, one of the main drawbacks of using poly(e-caprolactone) in the biomedical and pharmaceutical fields is represented by its low biodegradation rate. To overcome this limitation, electrospinning of PCL blended with a water-soluble poly(N-vinyl-2-pyrrolidone) was used to fabricate scaffolds with tunable fiber surface morphology and controllable degradation rates. Electrospun scaffolds revealed a highly immiscible blend state. The incorporated PVP phase was dispersed as inclusions within the electrospun fibers, and then easily extracted by immersing them in cell culture medium, exhibiting nanoporosity on the fiber surface. As a striking result, nanoporosity facilitated not only fiber biodegradation rates, but also improved cell attachment and spreading on the blend electrospun scaffolds. The present findings demonstrate that simultaneous electrospinning technique for PCL with water-soluble PVP provides important insights for successful tuning biodegradation rate for the PCL electrospun scaffolds but not limited to expand other high valuable biocompatible polymers for the future biomedical applications, ranging from tissue regeneration to controlled drug delivery.

In the present work we demonstrate a powerful technique for fabricating biocompatible and biodegradable PVA/HAp nanocomposite fibers in order to mimic mineralized hard tissues for bone regeneration purpose by applying the electro spinning process. Various techniques, including TEM, HR-TEM, SEM, XRD, DSC, TGA, FTIR spectroscopy were performed to characterize the resulting electrospun PVA/HAp composite nanofibers in comparison with pure PVA and PVA/HAp nanocomposites before electrospinning. Morphological investigation showed that the HAp nanoparticles exhibit nanoporous morphology, which provides enlarged interfaces being a prerequisite for physiological and biological responses and remodeling to integrate with the surrounding native tissue. The most striking physiochemical feature of the electrospun PVA/HAp composite nanofibers is that the HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA fibers as confirmed by electron microscopy and XRD. This feature bears strong resemblance to the nanostructure of mineralized hard tissues serving as building block of bone. Furthermore, the PVA as matrix and HAp nanorods as inorganic phases strongly interact through hydrogen bonds within the electrospun PVA/HAp nanocomposite fibers. The strong bonding due to the presence of a great extent of OH groups in the PVA polymer and the HAp nanorods leads improved thermal properties. The hybrid electrospinning shown in the present work provides great potential as a convenient and straightforward technique for the fabrication of biomimicked mineralized hard tissues suitable for bone and dentin replacement and regeneration. However, a great challenge still exists mainly in how to stabilize the electrospun PVA/Hap nanofibers when in contact with an aqueous medium. Such deficiency could be resolved by proper chemical and/or physical treatments of the material that are currently under investigation.

Macroporous ZnO membranes with a strong photocatalytic effect and high mechanical flexibility were prepared from inner shell membranes (ISM) of avian eggshells as templates after performing low-temperature ZnO atomic layer deposition (ALD). In order to evaluate the potential merits and general applicability of the ZnO structures, a comparative study of two membranes with coatings of either TiO2 or ZnO, processed under similar conditions, was performed. The study includes crystallographic features, mechanical and thermal stability and bactericidal efficiency. Both, the ZnO and the TiO2 coated membranes clearly exhibited bactericidal effects as well as mechanical flexibility and thermal stability even at relatively high temperatures. The ZnO membranes, even though prepared at fairly low temperatures (approximately 100 degrees C), exhibited polycrystalline phases and showed a good bactericidal efficiency as well as higher mechanical flexibility than the TiO2 coated membranes. This study shows the benefits of low-temperature ZnO ALD i.e., the thermally non-destructive nature, which preserves the mechanical stability and the native morphology of the templates used, together with an added functionality, i.e. the bactericidal effect.

Based on the biomimetic approaches the present work describes a straightforward technique to mimic not only the architecture (the morphology) but also the chemistry (the composition) of the lowest level of the hierarchical organization of bone. This technique uses an electrospinning (ES) process with polyvinyl alcohol (PVA) and hydroxyapatite (HAp) nanoparticles. To determine morphology, crystalline structures and thermal properties of the resulting electrospun fibers with the pure PVA and PVA/HAp nanocomposite (NC) before electrospinning various techniques were employed, including transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). In addition, FT-IR spectroscopy was carried out to analyze the complex structural changes upon undergoing electrospinning as well as interactions between HAp and PVA. The morphological and crystallographic investigations revealed that the rod-like HAp nanoparticles exhibit a nanoporous morphology and are embedded within the electrospun fibers. A large number of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA fibers, which closely resemble the naturally mineralized hard tissues of bones. Due to abundant OH groups present in PVA and HAp nanorods, they strongly interact via hydrogen bonding within the electrospun PVA/HAp NC fibers, which results in improved thermal properties. The unique physiochemical features of the electrospun PVA/HAp NC nanofibers prepared by the ES process will open up a wide variety of future applications related to hard tissue replacement and regeneration (bone and dentin), not limited to coating implants.

10 pags., fig. 7, Polymorphism found in nanofibres of polyamide 6 (PA6) and PA6/clay nanocomposite (PA6–NC), prepared by an electrospinning process, was studied by transmission electron microscopy (TEM) and variable-temperature wide angle X-ray scattering (WAXS), and compared with the polymorphic changes occurring in the pre-electrospun bulk materials. TEM results, concerning morphology and dispersion of the nanoclays, reveal that the produced electrospun nanofibres have an average diameter of 50 nm, and nanoclays are much more uniformly dispersed in the electrospun PA6–NC fibres than in the pristine PA6–NC. According to WAXS measurements, both types of electrospun nanofibres predominantly consist of γ-form crystals of PA6. Upon heating, from room temperature to the melting point, a number of successive transitions are observed for both systems, namely, crystalline γ to α′, α′ to α and α to the “amorphous” δ-form due to breakage of hydrogen bonds. On subsequent cooling, it has been observed, for the first time, that the development of crystalline forms for both systems is quite different from each other. The molten electrospun pure PA6 fibres first crystallize in the high temperature α′-form, and then they show the room temperature α-form. For these nanofibres, during a temperature cycle of heating and cooling, the initial γ-form crystals completely turn into the α-form crystals as in bulk PA6. In contrast, for the electrospun nanofibres of the PA6–NC, the γ-form crystals are preserved after completing a thermal cycle down to room temperature. The present findings on the evolution of polymorphism in the electrospun nanofibres of both systems provide useful information regarding their use as reinforcing elements in polymer composites.