Controllable Degradation Rate Research Articles

“From the Nature for the Nature”: An Eco-Friendly Antifouling Coating Consisting of Poly(lactic acid)-Based Polyurethane and Natural Antifoulant

“From the nature, for the nature” is an instructive strategy to develop environment-friendly antifouling coatings. In this work, bio-sourced poly(lactic acid)-based polyurethane with hydrolyzable triisopropylsilyl acrylate (TSA) side groups has been prepared via thiol–ene reaction and polyaddition. Such a polymer exhibits high adhesion strength (∼2.0 MPa) and a controlled degradation rate tuned by varying its soft segment and TSA content. An environment-friendly coating is prepared with the polymer and an eco-friendly antifoulant (butenolide) derived from marine bacteria. Our study shows that butenolide can be released from the coating in continuous manner with a controlled rate as the polymer degrades in seawater. Digital holographic microscopy tracking analysis demonstrates that the coating can effectively inhibit the adhesion of marine bacteria Pseudomonas sp. Marine field test shows that such coating has excellent antifouling ability for more than 3 months.

Dual-Functioning Scaffolds for the Treatment of Spinal Cord Injury: Alginate Nanofibers Loaded with the Sigma 1 Receptor (S1R) Agonist RC-33 in Chitosan Films.

The present work proposed a novel therapeutic platform with both neuroprotective and neuroregenerative potential to be used in the treatment of spinal cord injury (SCI). A dual-functioning scaffold for the delivery of the neuroprotective S1R agonist, RC-33, to be locally implanted at the site of SCI, was developed. RC-33-loaded fibers, containing alginate (ALG) and a mixture of two different grades of poly(ethylene oxide) (PEO), were prepared by electrospinning. After ionotropic cross-linking, fibers were incorporated in chitosan (CS) films to obtain a drug delivery system more flexible, easier to handle, and characterized by a controlled degradation rate. Dialysis equilibrium studies demonstrated that ALG was able to form an interaction product with the cationic RC-33 and to control RC-33 release in the physiological medium. Fibers loaded with RC-33 at the concentration corresponding to 10% of ALG maximum binding capacity were incorporated in films based on CS at two different molecular weights—low (CSL) and medium (CSM)—solubilized in acetic (AA) or glutamic (GA) acid. CSL- based scaffolds were subjected to a degradation test in order to investigate if the different CSL salification could affect the film behavior when in contact with media that mimic SCI environment. CSL AA exhibited a slower biodegradation and a good compatibility towards human neuroblastoma cell line.

Dual-modal non-invasive imaging in vitro and in vivo monitoring degradation of PLGA scaffold based gold nanoclusters.

Biodegradable scaffolds play an important role in tissue engineering, and appropriate degradation and resorption rates of these scaffolds are necessary to accommodate tissue growth. Synthetic polymers are frequently used because of their ease of production, good biocompatibility and controllable degradation rates. However, monitoring the degradation of these polymers in vivo by a noninvasive approach remains limited. In this study, we designed a composite scaffold by labeling poly(lactic-co-glycolic acid) (PLGA) with gold nanoclusters (Au NCs), which were used for tracking in vivo degradation through dual-modal fluorescence/computed tomography (CT) imaging. The diameter of the Au NCs was approximately 2.5 nm, and the emission peak was at a wavelength of 700 nm. After labeling PLGA with the Au NCs, the fluorescence intensity of the Au NC/PLGA composite scaffold reached 9.0 × 109 (p/s/cm2/sr)/(μW/cm2), and the CT density of the scaffold increased to 200 HU. After the composite scaffold was implanted subcutaneously into nude mice, a continuous decrease in the fluorescence signal and CT value was observed. The mean fluorescence intensity was 8.3 × 109, 3.17 × 109, 2.26 × 109, 2.11 × 109, and 1.82 × 109 (p/s/cm2/sr)/(μW/cm2) from the first week to the fifth week, respectively. The mean CT value changed from 222.6 to 185.9, 149.1, 112.5, and 55.2 (Hounsfield unit, HU) at the different timepoints. Compared with the change in the fluorescence intensity, the change in the CT value was similar to the change in the weight, and the Pearson correlation coefficient between the change in the CT value and weight was 0.8626. Furthermore, the structure and morphology of the scaffolds at different timepoints were analyzed by three-dimensional (3-D) reconstruction. This novel method of noninvasive dynamic monitoring of biodegradable polymers in vivo provides insight into choosing suitable biomaterials for tissue engineering and regenerative medicine.

A biodegradable multifunctional porous microsphere composed of carrageenan for promoting imageable trans-arterial chemoembolization

Trans-arterial chemoembolization (TACE) has been a mainstream treatment for hepatocellular carcinoma (HCC), accordingly there are more requirements for embolic agents’ properties, mainly concentrated on biodegradability and imaging function. A new kind of biodegradable multifunctional porous microspheres (BMPMs) with internal coarse plications are ingeniously designed and manufactured, consisting of carrageenan, inhexol and superparamagnetic iron oxide nanoparticle (SPIO). BMPMs’ sound roundness and excellent swelling behavior guarantee them to be smoothly transported into appointed arteries’ ends and achieve satisfactory embolization effect. Porous structure together with sulphate groups on BMPMs’ skeleton weaved by cross-linked carrageenan contributes to a marvelous doxorubicin hydrochloride (Dox) loading capacity over 45 mg Dox per mL of swollen microspheres, as well as a controllable degradation rate by allowing enzymes to infiltrate into BMPMs through holes, degrading 20–35% after two months in vitro. Inner coarse plications enable BMPMs to effectively combine with iohexol via hydrophilic effect and SPIO by blocking, which can further exhibit a decent imaging performance under digital subtraction system (DSA) and magnetic resonance imaging (MRI) for optimization of current TACE and development of a more advanced imageable TACE (iTACE). Safety evaluation and animal experiment manifest that BMPMs are reliable enough and hold great potential and competitiveness of being used in curing HCC.

3D Bioprinting of the Sustained Drug Release Wound Dressing with Double-Crosslinked Hyaluronic-Acid-Based Hydrogels.

Hyaluronic acid (HA)-based hydrogels are widely used in biomedical applications due to their excellent biocompatibility. HA can be Ultraviolet (UV)-crosslinked by modification with methacrylic anhydride (HA-MA) and crosslinked by modification with 3,3′-dithiobis(propionylhydrazide) (DTP) (HA-SH) via click reaction. In the study presented in this paper, a 3D-bioprinted, double-crosslinked, hyaluronic-acid-based hydrogel for wound dressing was proposed. The hydrogel was produced by mixing HA-MA and HA-SH at different weight ratios. The rheological test showed that the storage modulus (G’) of the HA-SH/HA-MA hydrogel increased with the increase in the HA-MA content. The hydrogel had a high swelling ratio and a high controlled degradation rate. The in vitro degradation test showed that the hydrogel at the HA-SH/HA-MA ratio of 9:1 (S9M1) degraded by 89.91% ± 2.26% at 11 days. The rheological performance, drug release profile and the cytocompatibility of HA-SH/HA-MA hydrogels with loaded Nafcillin, which is an antibacterial drug, were evaluated. The wound dressing function of this hydrogel was evaluated by Live/Dead staining and CCK-8 assays. The foregoing results imply that the proposed HA-SH/HA-MA hydrogel has promise in wound repair applications.

Structural and electrochemical study of resorbable Ca32Mg12Zn38Yb18-xBx (x=1, 2, 3) metallic glasses in Ringer's solution

A new class of CaZn-based bulk glassy alloys with minor addition of boron and enhanced corrosion resistance for use in bioresorbable materials is introduced. The CaMgZnYbB alloys represent a new family of biomaterials with potential applications in orthopedic implants with controlled degradation rates and corrosion in the human body. The effect of substituting Yb for B in the structure on the corrosion and mechanical properties of quinternary Ca32Mg12Zn38Yb18-xBx (x = 1,2,3 at.%) alloys was investigated using X-ray diffraction, high-resolution transmission electron microscopy, differential scanning calorimetry, immersion and electrochemical polarization, compressive tests, and hardness measurements. The corrosion behavior was also evaluated using electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Microstructural investigations showed that the Ca32Mg12Zn38Yb16B2 alloy was mainly amorphous, while small reflections from nanocrystals were observed in Ca32Mg12Zn38Yb17B1 and Ca32Mg12Zn38Yb15B3. Electrochemical polarization and immersion tests in Ringer's solution at 37 °C revealed that the CaMgZnYbB alloys had significantly higher corrosion resistance than CaMgZn alloys. Electrochemical impedance spectroscopy of alloys showed only single capacitive loops. The corrosion products were identified as CaO, MgO, Mg(OH)2, and CaCO3. The compressive strengths of the alloys from 220 MPa to 283 MPa were suitable for implant applications.

In Vitro Biodegradation and Biocompatibility of Mg–HA-Based Composites for Orthopaedic Applications: A Review

Magnesium (Mg)-based material systems offer great potential for healing bone fracture and defects, in terms of reduced stress shielding effect and non-toxicity, due to their biodegradability and biocompatibility. However, an issue with controlling degradation rate of Mg in an intraosseous (occurring within bone) environment has impeded their application in orthopaedics. As a solution to this problem, Mg can be combined with other corrosion-resistant and bioactive materials to form composite. Hydroxyapatite (HA) is an attractive bioceramic for implants due to its similar chemical composition to the apatite found in bone. Thus, incorporation of HA in Mg assists in enhancing multiple engineering properties that are critical for its widespread use in orthopaedic application. Tremendous improvement in the mechanical and degradation properties of HA-reinforced Mg composite, along with their impressive biocompatibility, has led to further interest in research, which has resulted in some clinical trials of Mg–HA-based composites, as well. This review article summarises researches, carried out till date on Mg–HA-based composite, with a special focus on significant role of HA in tuning the degradation and mechanical behaviour of Mg-based materials. The detailed summary on biocompatibility of Mg–HA-based composites has also been covered. A comprehensive understanding on biocompatibility and degradation behaviour of Mg–HA system is needed to assess the potential of these composites in orthopaedic application. However, such review is missing in available literatures. On the basis of current studies available on Mg–HA-based composites for orthopaedic application, guidelines for future application in clinical trials have also been framed and presented in this review article.

3D printing of calcium phosphate bioceramic with tailored biodegradation rate for skull bone tissue reconstruction

The bone regenerative scaffold with the tailored degradation rate matching with the growth rate of the new bone is essential for adolescent bone repair. To satisfy these requirement, we proposed bone tissue scaffolds with controlled degradation rate using osteoinductive materials (Ca-P bioceramics), which is expected to present a controllable biodegradation rate for patients who need bone regeneration. Physicochemical properties, porosity, compressive strength and degradation properties of the scaffolds were studied. 3D printed Ca-P scaffold (3DS), gas foaming Ca-P scaffold (FS) and autogenous bone (AB) were used in vivo for personalized beagle skull defect repair. Histological results indicated that the 3DS was highly vascularized and well combined with surrounding tissues. FS showed obvious newly formed bone tissues. AB showed the best repair effect, but it was found that AB scaffolds were partially absorbed and degraded. This study indicated that the 3D printed Ca-P bioceramics with tailored biodegradation rate is a promising candidate for personalized skull bone tissue reconstruction.

Structure variation and properties enhancement of uniaxial stretching poly(l‐lactic acid)/eggshell powder composites

ABSTRACTBiodegradable poly(l‐lactic acid) (PLLA)/eggshell (ES) powder composites were prepared by melt blending and uniaxial stretching above the glass‐transition temperature of PLLA. Scanning electron microscopy analyses revealed that micropores appeared in stretched composites. Porosity was affected by two factors, stretch ratios, and ES contents. Differential scanning calorimetry and wide‐angle X‐ray diffraction results demonstrated that strain‐induced crystallization in α‐form could be achieved in PLLA matrix. This superstructure improved multifunctional performance of PLLA composites. The exceptional combination of strength, modulus, and ductility of stretched PLLA90/ES10 composites with a stretch ratio of 6 were demonstrated, exceeding neat PLLA with the increments of 148, 190, and 507% in breaking strength, modulus, and elongation at break (140.8 MPa, 3810 MPa, and 35.2%), respectively. Meanwhile, the enhancement of thermomechanical properties due to high crystallinity and controllable degradation rates resulting from porosity were obtained by adjusting the composites compositions and/or stretch ratios. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48158.

In vitro degradation behavior of Mg wire/poly(lactic acid) composite rods prepared by hot pressing and hot drawing

In this study, we prepared Mg wire/poly(lactic acid) composite rods by hot pressing (HP) and hot drawing (HD) processes, which show desirable application potential as a biodegradable implant in orthopedics. The influences of the volume content of Mg wires and processing steps on the degradation behavior of composite rods as well as the mutual influence between Mg and poly(lactic acid) (PLA) during degradation were investigated. During degradation, the improved interface bonding between Mg and PLA by micro-arc oxidation can effectively inhibit the diffusion of the medium from the ends to the central part, supported by XR-CT results, which show the degradation cracks in PLA initiated and propagated along the radial direction of the rod rather than the axial direction. When compared with the hot pressed rod, the three passes hot drawn rod had lower degradation rate and better strength retention during long-time immersion. This is ascribed to the higher crystallinity of the PLA matrix by HD. For both hot pressed and hot drawn rods, more Mg content of the wires will result in an increase in the degradation rate of PLA due to alkaline catalytic hydrolysis. Therefore, we can not only predict the degradation period by the present degradation mathematical model but also further control degradation rate by adjusting processing steps and wire volume content. This will be helpful for future material design and indication selection. Statement of significanceWe investigated the influence of interface microstructure, self-reinforced PLA matrix, and wire volume content on the degradation behavior and clarified the differences in the degradation mechanism of composite rods. The 3D morphology of cracks in composite rods enlightened us a clear understanding about the emergence and evolution of cracks, which revealed the reason for the failure of composite rods. The degradation model can be used to predict the degradation period and provide valuable information for their future application.

LOC103691336/miR-138-5p/BMPR2 axis modulates Mg-mediated osteogenic differentiation in rat femoral fracture model and rat primary bone marrow stromal cells.

Intramedullary stabilization is frequently used to treat long bone fractures. Since implant removal can become technically very challenging with the potential to cause further tissue damage, biodegradable materials are emerging as alternative options. Magnesium (Mg)-based biodegradable implants have a controllable degradation rate and good tissue compatibility, which makes them attractive for musculoskeletal research. Herein, the degradation of Mg and steel implants, the pathological characteristics and osteoblast differentiation in mice femora were examined. To investigate the molecular mechanism, we analyzed the differentially expressed long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) in Mg-implanted or stain-steel-implanted callus tissues. lncRNA LOC103691336 was upregulated in Mg-implanted tissues and most relevant to BMPR2, a kinase receptor of BMPs with an established role in osteogenesis. The knockdown of LOC103691336 attenuated Mg-mediated osteogenic differentiation. Furthermore, miR-138-5p, previously reported to inhibit osteogenic differentiation, could bind to LOC103691336 and BMPR2 in bone marrow stromal cells (BMSCs). LOC103691336 competed with BMPR2 for miR-138-5p binding in BMSCs to attenuate the inhibitory effect of miR-138-5p on BMPR2 expression. Finally, the effect of LOC103691336 knockdown on Mg-mediated osteogenic differentiation could be attenuated by miR-138-5p inhibition. In conclusion, we provided a novel mechanism of Mg implants mediating the osteogenesis differentiation and demonstrated that Mg implants may be promising for improving fracture healing.

Fabrication of bi-layer photocrosslinked GelMA/PEGDA fibrous membrane for guided bone regeneration materials

A novel bi-layer gelatin methacrylamine (GelMA)/poly (ethylene glycol) diacrylate (PEGDA) fibrous membrane was fabricated by using electronspining and photo-crosslinking techniques. Compared with the crosslinked GelMA fibrous membrane, the crosslinked GelMA/PEGDA fibrous membrane have several times stronger mechanical properties and show a controllable degradation rate of more than 8 weeks in PBS or collagenase type I solution. The upper side of crosslinked GelMA/PEGDA fibrous membrane retard the proliferation of fibroblast and lower side benefit the proliferation of osteoblast. These properties are especially beneficial to guided bone regeneration (GBR) material used in periodontal surgery. Furthermore, the physical properties, degradation ratio, cell adhesion and proliferation can be fine-tuned by control the crosslinking time and PEGDA.

Ultrafast in situ forming poly(ethylene glycol)-poly(amido amine) hydrogels with tunable drug release properties via controllable degradation rates

Fast in situ forming, chemically crosslinked hydrogels were prepared by the amidation reaction between N-succinimidyl ester end groups of multi-armed poly(ethylene glycol) (PEG) and amino surface groups of poly(amido amine) (PAMAM) dendrimer generation 2.0. To control the properties of the PEG/PAMAM hydrogels, PEGs were used with different arm numbers (4 or 8) as well as different linkers (amide or ester) between the PEG arms and their terminal N-succinimidyl ester groups. Oscillatory rheology measurements showed that the hydrogels form within seconds after mixing the PEG and PAMAM precursor solutions. The storage moduli increased with crosslink density and reached values up to 2.3 kPa for hydrogels based on 4-armed PEG. Gravimetrical degradation experiments demonstrated that hydrogels with ester linkages between PEG and PAMAM degrade within 2 days, whereas amide-linked hydrogels were stable for several months. The release of two different model drugs (fluorescein isothiocyanate-dextran with molecular weights of 4·103 and 2·106 g/mol, FITC-DEX4K and FITC-DEX2000K, respectively) from amide-linked hydrogels was characterized by an initial burst followed by diffusion-controlled release, of which the rate depended on the size of the drug. In contrast, the release of FITC-DEX2000K from ester-containing hydrogels was governed mainly by degradation of the hydrogels and could be modulated via the ratio between ester and amide linkages. In vitro cytotoxicity experiments indicated that the PEG/PAMAM hydrogels are non-toxic to mouse fibroblasts. These in situ forming PEG/PAMAM hydrogels can be tuned with a broad range of mechanical, degradation and release properties and therefore hold promise as a platform for the delivery of therapeutic agents.

Research progress of bioactive glasses based bone repair materials

Bioactive glasses (BGs) are a kind of biomaterials with osteoconductive and osteoinductive properties and are able to create a strong bond with host bone and promote osteogenesis after implantation. According to their compositions, bioactive glasses can be classified as silicate BGs, phosphate BGs, and borate BGs. Nowadays, silicate BGs are still the most common, while phosphate BGs and borate BGs have higher dissolution and degradation rates. Melt-quenching and sol-gel process are two basic methods to produce melt-derived BGs and sol-gel BGs, respectively. The latter requires lower heat treatment temperature with higher specific surface area and biological activity. Bioactive glass-ceramics can be obtained by heat treatment, which improves the mechanical strength but slightly reduces the bioactivity. Nano-bioactive glasses with the higher specific surface area can be obtained by changing the structure size of the materials by other treatment methods. On this basis, 3D BGs scaffolds can be made, and hybrid BGs scaffolds as well by combining with other biomaterials to obtain the 3D interconnected pores with the hierarchical or bionic structures, to enhance the mechanical strength, osteogenic activity and provide mechanical support suitable for the host bone. However, the bioactivity of BGs depends on the degradation rate, to some extent, which is contradictory to the mechanical strength. An appropriate porosity or controllable degradation rate can be selected to meet the common needs of early support and osteogenesis. In basic studies, it was found that BGs could act on cells by releasing ions or through the macropinocytosis pathway, up-regulating the expression of related genes or promoting osteogenesis. The degradation rates of BGs are related to their structures and compositions, which enables the quantitative prediction of the change of mechanical strength during degradation. Progress has also been made in structural mechanics and testing methods.

Acetic Acid Etching of Mg-xGd Alloys

Mg-xGd alloys show potential to be used for degradable implants. As rare earth containing alloys, they are also of special interest for wrought products. All applications from medical to engineering uses require a low and controlled degradation or corrosion rate without pitting. Impurities from fabrication or machining, like Fe inclusions, encourage pitting, which inhibits uniform material degradation. This work investigates a suitable etching method to remove surface contamination and to understand the influence of etching on surface morphology. Acetic acid (HAc) etching as chemical surface treatment has been used to remove contamination from the surface. Extruded Mg-xGd (x = 2, 5 and 10) discs were etched with 250 g/L HAc solution in a volume of 5 mL or 10 mL for different times. The microstructure in the near surface region was characterized. Surface characterization was done by SEM, EDS, interferometry, and ToF-SIMS (time-of-flight secondary ion mass spectrometry) analysis. Different etching kinetics were observed due to microstructure and the volume of etching solution. Gd rich particles and higher etching temperatures due to smaller etchant volumes promote the formation of pits. Removal of 2–9 µm of material from the surface was sufficient to remove surface Fe contamination and to result in a plain surface morphology.

Developing composite of ZE41 magnesium alloy- calcium by friction stir processing for biodegradable implant applications

Abstract In the present work, ZE41Mg alloy - Ca composite was produced by friction stir processing (FSP) targeted for biodegradable implant applications. Microstructural studies revealed grain refinement in the composite as 7 µm from a starting size of 110 µm. Due to grain refinement, increased hardness was observed in the composite. Degradation behavior was analyzed by immersion method conducted in Ringers physiological solution for 168 h. From the immersion studies, it was a clear observation that the degradation rate of composite has been decreased with increase in the immersion time compare with unprocessed ZE41. pH measurements and also surface phase and morphology analysis done by X-Ray diffractometry (XRD) and scanning electron microscopy (SEM) respectively, revealed that the corrosion behavior was better for the composite compared with the unprocessed ZE41. The promising behavior of the composite can be attributed to the grain refinement, texture effect and the presence of Ca which decreased the formation of magnesium hydroxide and promoted better corrosion resistance. Hence from the preliminary results, it can be understood that ZE41-Ca composites can be successfully produced by FSP targeted for degradable implant applications with controlled degradation rate without deteriorating the mechanical properties.

Shear-thinning hyaluronan-based fluid hydrogels to modulate viscoelastic properties of osteoarthritis synovial fluids.

Hyaluronan (hyaluronic acid, HA) has been extensively explored as an attractive biomaterial for biomedical and pharmaceutical applications due to its unique physiological properties. In particular, HA is a major component of synovial fluid in normal knee joints and provides viscoelastic properties to synovial fluid. In osteoarthritic joints, synovial fluid loses its unique viscoelastic and lubrication properties. Intra-articular injection of HA in osteoarthritic knee joints is believed to restore viscoelasticity and lubrication abilities to synovial fluid. However, the main drawback of HA is its rapid degradation in synovial fluid. In order to overcome the problem of rapid clearance of HA, a HA-based hydrogel (vinyl sulfone-modified HA crosslinked by dithiol-terminated poly(ethylene glycol), HA-VS/SH-2-PEG) was synthesized in this study. Injectable fluid hydrogels (viscosupplements) possessing tunable viscoelasticity and controllable degradation rates were then prepared by adding HA-VS/SH-2-PEG microgels to HA solutions. The resultant viscosupplements exhibit enhanced viscoelastic properties, lubrication effects, efficient triamcinolone acetonide payload capacity, and high resistance to enzymatic degradation along with good biocompatibility and the capability to inhibit the progression of osteoarthritis in vivo. Overall, the results provide support for the use of injectable fluid hydrogels as a strategy for the treatment of osteoarthritis and potential for the clinical translation.

Elucidation of the time-dependent degradation process in insoluble hyaluronic acid formulations with a controlled degradation rate

Degradation rate of hyaluronic acid to prolong its stability in vivo would be beneficial. We investigated a potential solution for prolonging the stability of hyaluronic acid within the body. We focused on decreasing the swelling ratio to slow the degradation rate of hyaluronic acid by insolubilizing sodium hyaluronate without using potentially harmful substances such as crosslinkers or modifiers. Hyaluronic acid formulations were created with three different swelling ratios and time-dependent morphological changes in hyaluronic acid formulations and were scored based on each swelling ratio. In vivo degradation was modeled in simulated body fluid and the extent of decay of test membranes were monitored over time. Results showed that, by adjusting the swelling ratio, the degradation rate of hyaluronic acid formulation could be controlled. Our research could lead to improvements in many products, not only preventive materials for postoperative adhesions, but also pharmaceutical products such as osteoarthritis treatments and cosmetic medicines.

Synthesis and characterization of conductive neural tissue engineering scaffolds based on urethane-polycaprolactone

Polymeric biomaterials play a key role in enhancement of lengthy nerve regeneration and various types of scaffolds were used to pave the way for nerve regeneration. Electrospun fibrous scaffolds have special potential applicability in controlling the cell behaviors such as adhesion, growth, proliferation and function. This study attempted to design a conductive and porous fibrous scaffold containing polycaprolactone (PCL) and polyaniline (PANI) with controllable degradation rate by adding urethane groups in scaffold structures. FTIR and NMR analysis was used to characterize the chemical bonds. Morphology, porosity, conductivity and degradation rate of scaffolds were also evaluated. To assess the cell–scaffold interaction, PC-12 cell line was cultured on the scaffolds. Results showed that the degradation rate of composite samples significantly increased in 50 time period. It seems that these results suggest that the composite fibrous scaffolds having proportions of UPCL/PCL/PANI45:20:35 exhibit the most balanced properties that meet all of the required specifications for neural cells and possess a potential application in neural tissue engineering.

Fabrication of magnesium ecap based maxillary miniplate-typed implant through the method of micro forming

Research and study on a degradable implant for bone fracture fixation has received great attention. This had to do with a problem, which in some cases, require doctors to do re-surgery to remove the implant from the patient after the fractured bone was healed. The removal surgery could cause several problems, such as the need for another recovery period and the high cost of the removal surgery itself. Several methods are developed to control degradation rate to match with healing rate. One of such method is the grain refinement technique using severe plastic deformation. In this paper, a study of fabrication of a miniplate implant for maxillofacial region using magnesium which passed severe plastic deformation using Equal Channel Angular Pressing (ECAP) was performed. The micro-forming fabrication method is selected to form the miniplate. It is shown that the accuracy precision of the process was achieved with a reasonable result compare to the design. The most crucial part form miniplate design is the hole which shows low variation in diameter, 1.43 %. It shows that the method of micro-forming has great potential to fabricate miniplate using magnesium ECAP. Further work is necessary to conduct finishing process on the miniplate.