Polylactic Acid Scaffolds Research Articles

Mechanical Characteristics of Individualized Biodegradable Augmentation Scaffold-In Vitro Pilot Study.

The alveolar ridge reconstruction of vertical and combined bone defects is a non-predictable procedure with varying percentages of success. The greatest challenge for vertical and combined bone augmentation is to maintain mechanical stability of the bone graft; therefore, it is mandatory to provide and preserve space for bone regeneration. The development of biomaterials and 3D printing has enabled the use of polymer scaffolds in the reconstruction of alveolar ridge defects. The aim of this pilot study was to evaluate the mechanical characteristics of an innovative individualized biodegradable polylactic acid (PLA) scaffold, under dynamic conditions, simulating biodegradation and the influence of masticatory forces. After the design and 3D printing of PLA scaffolds, two groups of 27 scaffolds were formed according to the compression testing procedure. The compression tests were performed in occlusal and lateral directions. In each of the two groups, nine subgroups of three scaffolds were formed for different testing periods during in vitro degradation with a total period of 16 weeks. Results showed that biodegradation and load application had no significant influence on mechanical characteristics of tested scaffolds. It can be concluded that simulated masticatory forces and biodegradation do not significantly influence the mechanical characteristics of an individualized biodegradable augmentation scaffold.

Effect of the filling pattern in 3D-printed polylactic acid scaffolds on mechanical properties and cell proliferation for bone tissue regeneration

3D printing technology can control the shape and filling pattern of the scaffold very well and has been widely used in the preparation of bone repair scaffolds. Modifying the filling pattern of scaffolds to alter their mechanical properties and cellular adhesion holds immense significance. In this study, 3D-printed polylactic acid (PLA) scaffolds with different fibre angles (15°-90°) were prepared. The 90° scaffold showed the best mechanical properties and was suitable for repairing long bones. The 60° scaffold has balanced mechanical properties and is suitable for maxillofacial bone repair. The scaffold with a 30° angle was the best for cell adhesion and proliferation and was suitable for cancellous bone repair.

(158) Comparison Implants for Penile Girth Enlargement: PPLA Shaft vs Silicone Implant

Abstract Introduction Male dissatisfaction with the penis size is the most common manifestation of penile dysmorphophobia. Despite the diversity of penis enlargement methods a single safe technique that fully satisfies patients has not yet been developed. Objective The aim of this work is to compare the results of a combined operation on installation of a silicone implant or a porous polylactic acid (PPLA) scaffold impregnated with autologous stem cells with simultaneous ligamenotaxis to increase the length and circumference of the penis. Methods In 2017–2023 there were performed penis enlargement surgeries in 3 centers. In Ukraine and Poland 38 patients from were operated with implantation of a porous Max Pol PLLA scaffold, and in Mexico implantation of silicone implants Peniflex in 36 patients was performed. The results of penis enlargement were evaluated in the early (2 months) and long-term (36 months) periods. Results While implanting a silicone implant the majority of the patients - 31 (86.1%) are satisfied with the result, 27 (75%) patients mention an improvement in sexual life, 31 (86.1%) also mention an increase in their own self-sufficiency. At the same time, some patients mentioned the following complications: 2 (5.6%) patients mentioned displacement of the silicone matrix, 1 (2.8%) patient mentioned prolapse of the implant, 1 (2.8%) patient mentioned a decrease in erection (which did not improve after removal of the implant), in 1 (2.8%) case the silicone implant had to be removed due to the fact that the patient did not liked the appearance. While using a collagen-like matrix made of polymerized polylactic acid impregnated with autological stem cells in 38 patients, we have seen one significant complication - prolapse that caused the removal of the matrix (in men that had denied circumcision before implantation). However, 5 (13.2%) patients required additional polylactic acid gel injections between 6 and 36 months to optimize the shape or volume of the penis. 34 (89.5%) patients mentioned an improvement in the sexual function and sexual sensations of their partner, harmonization of relationships in a couple, and 36 (97.4%) men - an increase in a sense of self-sufficiency. In 3 years most of the patients 26 (68,4%) have been satisfied with particularly resolved implant but 13 (34.2) patients want to add some PLA gel as injection for penile girth recovery. Conclusions Thus, modern implants can improve the size and appearance of the penis, improve the quality of sexual life and the feeling of self-sufficiency in operated men. The use of silicone implants is simpler, it require only long drain 3–5 days. Most of operated patients were satisfied results of silicone implant. The use of a polymer matrix impregnated with autologuous stem cells requires a special biostem cell laboratory, more time for preoperative rehabilitation, but can be considered as more philological. Both methods can be considered as permanent and quite safe for penis enlargement. Disclosure No.

Standardization of 3D printing parameters to control the size and shape of pores in Polylactic acid scaffolds

AbstractThe challenge of three‐dimensional (3D) printing by polymeric extrusion in tissue bioengineering is to control with precision the microarchitecture and porous interconnectivity of scaffolds, as well as search for models that allow and facilitate the development of personalized constructs that meet optimal characteristics for the regeneration of significant bone defects. In this study, anatomically accurate scaffolds were designed and printed to a critical size defect from a microtomography image of the rat calvaria. Different software is used to design a scaffold with exact anatomy. With Ultimaker Cura software, distinct printing parameters were standardized, permitting the printing of different types of pores and graded porosity scaffolds, with exact adaptation to the bone defect, utilizing a commercial 3D printer with a fused deposition modeling technique and compensating for the limitations of the method. The scaffolds were characterized by evaluating their mechanical properties and surface characteristics (pore size and porosity), employing scanning electron microscopy images, verifying that the size and shape of the pores were controlled, and evaluating cell viability and cell distribution on the 3D printed scaffold. Therefore, this work proves that by standardizing the printing parameters, it was possible to print a unique customized scaffold, controlling the shape and size of pores.

A Combined Computational and Experimental Analysis of PLA and PCL Hybrid Nanocomposites 3D Printed Scaffolds for Bone Regeneration.

A combined computational and experimental study of 3D-printed scaffolds made from hybrid nanocomposite materials for potential applications in bone tissue engineering is presented. Polycaprolactone (PCL) and polylactic acid (PLA), enhanced with chitosan (CS) and multiwalled carbon nanotubes (MWCNTs), were investigated in respect of their mechanical characteristics and responses in fluidic environments. A novel scaffold geometry was designed, considering the requirements of cellular proliferation and mechanical properties. Specimens with the same dimensions and porosity of 45% were studied to fully describe and understand the yielding behavior. Mechanical testing indicated higher apparent moduli in the PLA-based scaffolds, while compressive strength decreased with CS/MWCNTs reinforcement due to nanoscale challenges in 3D printing. Mechanical modeling revealed lower stresses in the PLA scaffolds, attributed to the molecular mass of the filler. Despite modeling challenges, adjustments improved simulation accuracy, aligning well with experimental values. Material and reinforcement choices significantly influenced responses to mechanical loads, emphasizing optimal structural robustness. Computational fluid dynamics emphasized the significance of scaffold permeability and wall shear stress in influencing bone tissue growth. For an inlet velocity of 0.1 mm/s, the permeability value was estimated at 4.41 × 10-9 m2, which is in the acceptable range close to human natural bone permeability. The average wall shear stress (WSS) value that indicates the mechanical stimuli produced by cells was calculated to be 2.48 mPa, which is within the range of the reported literature values for promoting a higher proliferation rate and improving osteogenic differentiation. Overall, a holistic approach was utilized to achieve a delicate balance between structural robustness and optimal fluidic conditions, in order to enhance the overall performance of scaffolds in tissue engineering applications.

Bone morphogenetic protein-2 and pulsed electrical stimulation synergistically promoted osteogenic differentiation on MC-3T3-E1 cells.

Electrical stimulation (ES) plays an important role in regulating cell osteoblast differentiation. As a noninvasive rehabilitation therapy method, Es has a unique role in postoperative recovery. Bone morphogenetic protein-2 (BMP-2) is the most commonly used bioactive molecule in in situ tissue engineering scaffolds, and it plays an important regulatory role in the whole process of bone injury repair. In this study, the osteogenic regulation of MC-3T3-E1 cells was studied by combining pulsed electrical stimulation (PES) and different concentrations of BMP-2. The results showed that PES and BMP-2 could synergically promote the proliferation of MC-3T3-E1 cells. The qPCR results of osteoblast-related genes showed that PES was synergistic with BMP-2 to promote osteoblast differentiation mainly through the regulation of the Smad/BMP and insulin like growth factor 1 (IGF1) signaling pathways. The expression level of alkaline phosphatase (ALP) and alizarin red staining further demonstrated the synergistic effect of PES and BMP-2 on promoting osteogenic differentiation and mineralization of cells. PES and BMP-2 could also synergically promote cell proliferation, expression of collagen I (COL-I) and ALP, and cell mineralization on the 3D-printed polylactic acid scaffold. These results suggest that the use of PES can enhance the osteogenic effect of in situ bone repair scaffolds containing BMP-2, reduce the dose of BMP-2 alone, and reduce the possible side effects of high-dose BMP-2 in vivo.

Magnesium Hydroxide as a Versatile Nanofiller for 3D-Printed PLA Bone Scaffolds.

Polylactic acid (PLA) has attracted much attention in bone tissue engineering due to its good biocompatibility and processability, but it still faces problems such as a slow degradation rate, acidic degradation product, weak biomineralization ability, and poor cell response, which limits its wider application in developing bone scaffolds. In this study, Mg(OH)2 nanoparticles were employed as a versatile nanofiller for developing PLA/Mg(OH)2 composite bone scaffolds using fused deposition modeling (FDM) 3D printing technology, and its mechanical, degradation, and biological properties were evaluated. The mechanical tests revealed that a 5 wt% addition of Mg(OH)2 improved the tensile and compressive strengths of the PLA scaffold by 20.50% and 63.97%, respectively. The soaking experiment in phosphate buffered solution (PBS) revealed that the alkaline degradation products of Mg(OH)2 neutralized the acidic degradation products of PLA, thus accelerating the degradation of PLA. The weight loss rate of the PLA/20Mg(OH)2 scaffold (15.40%) was significantly higher than that of PLA (0.15%) on day 28. Meanwhile, the composite scaffolds showed long-term Mg2+ release for more than 28 days. The simulated body fluid (SBF) immersion experiment indicated that Mg(OH)2 promoted the deposition of apatite and improved the biomineralization of PLA scaffolds. The cell culture of bone marrow mesenchymal stem cells (BMSCs) indicated that adding 5 wt% Mg(OH)2 effectively improved cell responses, including adhesion, proliferation, and osteogenic differentiation, due to the release of Mg2+. This study suggests that Mg(OH)2 can simultaneously address various issues related to polymer scaffolds, including degradation, mechanical properties, and cell interaction, having promising applications in tissue engineering.

Sustainable 3D-printed β-galactosidase immobilization coupled with continuous-flow reactor for efficient lactose-free milk production

The production of low-lactose and lactose-free milk remains a critical challenge. Novel enzyme immobilization integrated with the flow reactor that could be applied to hydrolyze milk with cost-effectiveness, facilitation, and safety is highly expected. Here, we present a novel continuous-flow bioreactor loaded with β-galactosidase (β-Gal) covalently immobilized 3D-printed scaffolds for the production of lactose-free milk. 3D-printed polylactic acid (PLA) scaffolds modified by self-assembly of polyethyleneimine and sodium hyaluronate layers are rapidly branched with functional groups, followed by covalent immobilization of β-Gal using genipin as the cross-linker. The use of genipin allows efficient and stable immobilization of the enzyme (92.87 % immobilization efficiency), and the immobilized enzyme retains 90.53 % activity after 6th repeated use. Moreover, the 3D-printed scaffolds integrated into the flow reactor perturbed the fluids in the different reactors through directional channels, which improved the internal mass transfer to achieve high catalytic activity (94.20 % lactose hydrolysis efficiency). The lactose residues of milk reacted in the β-Gal flow reactor for 6 and 12 h were 1.87 g dL-1 and 0.38 g dL-1, which fully met the requirements of the national food safety standards for low-lactose and lactose-free milk. Due to the high efficiency of enzyme immobilization and the stable catalytic activity of the reactor, it has a broad application prospect for the production of low-lactose and lactose-free milk and other biocatalytic fields.

ELECTRICAL STIMULATION COMBINED WITH ADDITIVE MANUFACTURED 3D CONDUCTIVE SCAFFOLDS TOWARDS IMPROVED BONE-TISSUE ENGINEERING STRATEGIES

The growing number of non-union fractures in an aging population has increased the clinical demand for tissue-engineered bone. Electrical stimulation (ES) has been described as a promising strategy for bone regeneration treatments in several clinical studies. However the underlying mechanism by which ES augments bone formation is still poorly understood and its use in bone tissue engineering (BTE) strategies is currently underexplored. Additive manufacturing (AM) technologies (Fused Deposition Modeling/3D Printing) have been widely used in BTE due to their ability to fabricate scaffolds with a high control over their structural and mechanical properties in a reproducible and scalable manner. Thus, in this work, we combined AM methods with conductive biomaterials and ES to enhance the osteogenic differentiation of human bone marrow-derived mesenchymal stem/stromal cells (hBMSCs) envisaging improved BTE strategies.First, we started by developing AM-based electro-bioreactor devices containing medical-grade electrodes (stainless steel and Ti6Al4V) to apply ES to monolayer 2D cultures and 3D cell-seeded scaffolds. Computer modeling(Finite Element Analysis-FEA) was employed to predict the magnitude/distribution of electrical fields within the ES devices and along the different conductive scaffolds. Prior to scaffold culture, 5 different ES protocols were tested in terms of their ability to promote hBMSCs proliferation and osteogenic differentiation in 2D cultures. The best performance ES protocol was then used in two different AM-based BTE strategies: 1) Two different conductive scaffolds (conductive poly lactic acid (PLA) and titanium) were seeded with hBMSCs and cultured for 21 days under osteogenic medium conditions with and without ES and their biological performance was evaluated in comparison to non-conductive standard PLA scaffolds; 2) Different PEDOT:PSS-based coating solutions were screened to obtain PEDOT:PSS/Gelatin-coated 3D polycaprolactone (PCL) scaffolds with a high(11 S.cm-1) and stable electroconductivity. When cultured under ES, PEDOT:PSS/Gelatin-PCL scaffolds enhanced significantly hBMSCs osteogenic differentiation and mineralization(calcium deposition), highlighting their potential for BTE applications.Acknowledgements: Funding received from FCT through projects InSilico4OCReg (PTDC/EME-SIS/0838/2021), OptiBioScaffold (PTDC/EME-SIS/4446/2020) and BioMaterARISES (EXPL/CTM-CTM/0995/2021), and to the institutions iBB (UIDB/04565/2020), CDRSP (UIDB/04044/2020) and Associate Laboratory i4HB (LA/P/0140/2020).

Design and development of 3D printed shape memory triphasic polymer-ceramic bioactive scaffolds for bone tissue engineering.

Scaffolds for bone tissue engineering require considerable mechanical strength to repair damaged bone defects. In this study, we designed and developed mechanically competent composite shape memory triphasic bone scaffolds using fused filament fabrication (FFF) three dimensional (3D) printing. Wollastonite particles (WP) were incorporated into the poly lactic acid (PLA)/polycaprolactone (PCL) matrix as a reinforcing agent (up to 40 wt%) to harness osteoconductive and load-bearing properties from the 3D printed scaffolds. PCL as a minor phase (20 wt%) was added to enhance the toughening effect and induce the shape memory effect in the triphasic composite scaffolds. The 3D-printed composite scaffolds were studied for morphological, thermal, and mechanical properties, in vitro degradation, biocompatibility, and shape memory behaviour. The composite scaffold had interconnected pores of 550 μm, porosity of more than 50%, and appreciable compressive strength (∼50 MPa), which was over 90% greater than that of the pristine PLA scaffolds. The flexural strength was improved by 140% for 40 wt% of WP loading. The inclusion of WP did not affect the thermal property of the scaffolds; however, the inclusion of PCL reduced the thermal stability. An accelerated in vitro degradation was observed for WP incorporated composite scaffolds compared to pristine PLA scaffolds. The inclusion of WP improved the hydrophilic property of the scaffolds, and the result was significant for 40 wt% WP incorporated composite scaffolds having a water contact angle of 49.61°. The triphasic scaffold exhibited excellent shape recovery properties with a shape recovery ratio of ∼84%. These scaffolds were studied for their protein adsorption, cell proliferation, and bone mineralization potential. The incorporation of WP reduced the protein adsorption capacity of the composite scaffolds. The scaffold did not leach any toxic substance and demonstrated good cell viability, indicating its biocompatibility and growth-promoting behavior. The osteogenic potential of the WP incorporated scaffolds was observed in MC3T3-E1 cells, revealing early mineralization in pre-osteoblast cells cultured in different WP incorporated composite scaffolds. These results suggest that 3D-printed WP reinforced PLA/PCL composite bioactive scaffolds are promising for load bearing bone defect repair.

Direction-oriented fiber guiding with a tunable tri-layer-3D scaffold for periodontal regeneration.

Multilayered scaffolds mimicking mechanical and biological host tissue architectures are the current prerequisites for successful tissue regeneration. We propose our tunable tri-layered scaffold, designed to represent the native periodontium for potential regenerative applications. The fused deposition modeling platform is used to fabricate the novel movable three-layered polylactic acid scaffold mimicking in vivo cementum, periodontal ligament, and alveolar bone layers. The scaffold is further provided with multiple angulated fibers, offering directional guidance and facilitating the anchorage dependence on cell adhesion. Additionally, surface modifications of the scaffold were made by incorporating coatings like collagen and different concentrations of gelatin methacryloyl to enrich the cell adhesion and proliferation. The surface characterization of our designed scaffolds was performed using tribological studies, atomic force microscopy, contact angle measurement, scanning electron microscopy, and micro-computed tomography. Furthermore, the material characterization of this scaffold was investigated by attenuated total reflectance-Fourier transformed infrared spectroscopy. The scaffold's mechanical characterization, such as strength and compression modulus, was demonstrated by compression testing. The L929 mouse fibroblast cells and MG63 human osteosarcoma cells have been cultured on the scaffold. The scaffold's superior biocompatibility was evaluated using fluorescence dye with fluorescence microscopy, scanning electron microscopy, in vitro wound healing assay, MTT assay, and flow cytometry. The mineralization capability of the scaffolds was also studied. In conclusion, our study demonstrated the construction of a multilayered movable scaffold, which is highly biocompatible and most suitable for various downstream applications such as periodontium and in situ tissue regeneration of complex, multilayered tissues.

Design, fabrication, and characterization of 3D-printed ABS and PLA scaffolds potentially for tissue engineering

Additive manufacturing technologies are getting attention as a prospective substitute for conventional medical implant production methods owing to their unique manufacturing properties. In addition, biomaterials are required for bone repair and tissue engineering (BTE) techniques to provide scaffolds with the necessary biological and structural properties and improved performance. In this study, widely available biocompatible materials acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) are utilized for the design, fabrication, simulation, and mechanical characterization of 3D-printed scaffolds with two lay-down patterns potentially for bone tissue engineering. Mechanical properties of the 3D-printed scaffolds are determined by compression test and finite element analysis (FEA). Moreover, scanning electron microscope (SEM) images are also analyzed to determine the printing accuracy of the scaffolds. The porosity of the scaffolds is estimated both theoretically and through the liquid displacement method. Finally, the comparative analysis between PLA and ABS scaffolds indicates that the PLA scaffold has a higher potential for bone tissue regeneration. This study provides a notable engineering contribution by using a cost-efficient and easily available biomaterial as an alternative to bone tissue.

Surface Modification of Polylactic Acid Bioscaffold Fabricated via 3D Printing for Craniofacial Bone Tissue Engineering.

Bone tissue engineering is a promising solution for advanced bone defect reconstruction after severe trauma. In bone tissue engineering, scaffolds in three-dimensional (3D) structures are crucial components for cell growth, migration, and infiltration. The three-dimensional printing technique is well suited to manufacturing scaffolds since it can fabricate scaffolds with highly complex designs under good internal structural control. In the current study, the 3D printing technique was utilized to produce polylactic acid (PLA) scaffolds. BMSCs were seeded onto selected scaffolds, either hydrogel-mixed or not, and cultivated in vitro to investigate the osteogenic potential in each group. After osteogenic incubation in vitro, BMSC-seeded scaffolds were implanted onto rat cranium defects, and bone regeneration was observed after 12 weeks. Our results demonstrated that BMSCs were able to seed onto 3D-printed PLA scaffolds under high-resolution observation. Real-time PCR analysis showed their osteogenic ability, which could be further improved after BMSCs were mixed with hydrogel. The in vivo study showed significantly increased bone regeneration when rats' cranium defects were implanted with a hydrogel-mixed BMSC-seeded scaffold compared to the control and those without cell or hydrogel groups. This study showed that 3D-printed PLA scaffolds are a feasible option for BMSC cultivation and osteogenic differentiation. After mixing with hydrogel, BMSC-seeded 3D-printed scaffolds can facilitate bone regeneration.

Development of nanofibrous scaffolds containing polylactic acid modified with turmeric and hydroxyapatite/vivianite nanoparticles for wound dressing applications

Damaging the outer layer of the body (the skin) has been a common issue for decades. Fabrication of nanofibrous membranes via the electrospinning technique for the sake of making the wound healing process more facile has caught a lot of interest. For this purpose, a polymeric scaffold of polylactic acid (PLA) was doped with nanoparticles with different concentrations of turmeric/hydroxyapatite/vivianite/graphene oxide. The obtained membrane was tested by XRD, SEM, FTIR, and XPS. The surface topography of the scaffold has experienced changes upon adding different concentrations of the nanoparticles. The contact angle was measured by water droplets. It accentuated change in CA starting from 43.9o for pure condition of PLA to 67.7o for PLA/turmeric/vivianite. The thermogravimetric analysis (TGA) test stated that the PLA scaffold features are thermally stable in relatively high-temperature conditions initiating from room temperature to about 300 °C, meeting the maximum loss in mass of about 5 %. The cell viability was carried out in prepared vitro for the sample which contains PLA/turmeric/vivianite/GO, it was elucidated that the IC50 was around 3060 μg/ml.

Invited Session II: Retinal remodeling and regeneration: Developing autologous iPSC-RPE therapy for the treatment of AMD patients.

Age-related macular degeneration (AMD) is one the leading causes of vision loss in older people in the Western world. The disease is caused by degeneration of the retinal pigment epithelium (RPE) monolayer that supports photoreceptors. We used induced pluripotent stem cells (iPSC) to develop an autologous cell replacement therapy for treating dry AMD patients. Patients' blood cells were reprogrammed into iPSCs and differentiated iPSCs into RPE cells using a protocol developed in our lab. RPE cells were matured on a biodegradable polylactic co-glycolic acid (PLGA) scaffold for five weeks. Quality control assays confirmed the iPSC-RPE patch's purity, maturity, and functionality. Pre-clinical studies in rats and pigs demonstrated the safety and efficacy of iPSC-RPE-patch. Immune-compromised rats transplanted with a 0.5 mm iPSC-RPE patch showed no signs of tumor formation after nine months, confirming the safety profile. We laser-injured the RPE monolayer in the visual streak of pig eyes and, after 48 hours, transplanted the patch. Optical coherence tomography (OCT) confirmed the integration of the patch. A multi-focal electroretinogram (ERG) showed that the retinal layers' electric response was much higher than the lasered area without the implant. We started a phase I/IIa trial for an autologous iPSC-RPE patch to treat AMD. This ongoing trial will test the safety, feasibility, and integration of the iPSC-RPE patch in 12 AMD patients.

Synergistic effect of CaCO3 addition and cold atmospheric plasma treatment on the surface evolution, mechanical properties, and in-vitro degradation behavior of FDM-printed PLA scaffolds

The ease of processing and biocompatibility of polylactic acid (PLA) have made it a widely used material for fused deposition modeling (FDM)-based 3D printing. In spite of this, PLA suffers from some limitations for its extensive use in tissue engineering applications, including poor wettability, low degradation rate, and insufficient mechanical properties. To address the previously mentioned limitations, this study examined how combining in-process cold atmospheric plasma treatment with the inclusion of CaCO3 influences the properties of FDM-printed PLA scaffolds. Differential scanning calorimetry results showed that by incorporating CaCO3 micro-particles into the PLA matrix, heterogeneous nucleation promoted the matrix's crystalline content. Scanning electron microscopy analysis revealed that the surface of the PLA-CaCO3 scaffold exhibited increased roughness and improved interlayer bonding after undergoing plasma treatment. Atomic force microscopy revealed a significant (up to 80-fold) increase in the roughness value of PLA scaffolds after the incorporation of CaCO3 and subsequent cold plasma treatment. Furthermore, X-ray photoelectron spectroscopy analysis indicated that atmospheric plasma treatment substantially increased the presence of oxygen-containing bonds, leading to a significant reduction in the water contact angle, which decreased from 89° to 37°. According to the tensile test, the tensile modulus (634.1 MPa) and ultimate tensile strength (25.4 MPa) of PLA were markedly increased and reached 914.3 and 37.2 MPa, respectively, for the plasma-treated PLA-CaCO3 (PT-PLA-CaCO3). Additionally, the in-vitro degradation test showed that PT-PLA-CaCO3 scaffold exhibited higher degradation rate compared to the PLA-CaCO3 sample. Based on the obtained results, it appears that in-process cold atmospheric plasma treatment could serve as an efficient and straightforward method to enhance the properties of 3D-printed composite parts, particularly for tissue engineering applications.

Polycaprolactone, polylactic acid, and nanohydroxyapatite scaffolds obtained by electrospinning and 3D printing for tissue engineering

There is a deficit for bone tissue natural grafts that seek to be covered with synthetic substitutes. Scaffolds generated with 3D printing and electrospinning allow adequate mechanical properties maintaining a structure appropriate for cell growth. Here, a scaffold made up of three-dimensional (3D) printed PLA frameworks added with PCL/PLA/nHA nanofibers was manufactured. The framework showed mechanical properties similar to other reported bone substitutes, while the nanofibers showed diameters between 200 and 850 nm. Scaffolds were suitable for cell adhesion and proliferation when evaluated with fibroblasts, showing cell proliferation into the nanofiber network, a fundamental aspect in tissue engineering.

Effect of crystallization process on the electrical, and piezoelectric properties of PLA scaffolds

This paper investigates the fabrication and characterization of piezoelectric properties in electrospun polylactic acid (PLA) scaffolds for tissue engineering applications. The aim is to enhance the mechanical and electrical properties of the scaffolds to mimic native tissues. Thermo-mechanical processing techniques, including post-processing under various temperature, weight, and time conditions, are employed to modify the scaffolds. The effects of these processing parameters on the morphological, piezoelectric, and crystalline properties of the PLA scaffolds are examined. The scaffolds exhibit partially parallel beadles fibers with varying degrees of alignment and thickness, depending on the applied post-processing parameters. These morphological features play a crucial role in enhancing the piezoelectric properties of the scaffolds. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses demonstrate that thermo-mechanical processing promotes the formation of the α crystalline phase and increases the degree of crystallinity in the PLA scaffolds. The crystalline phase and orientation of the fibers are influenced by the applied weight, time, and temperature during post-processing. Furthermore, the study examines the electrical conductivity and ferroelectric properties of the PLA scaffolds. The results indicate enhanced piezoelectric properties in the scaffolds, as evidenced by the measured output voltages. However, ferroelectric behavior is not observed due to the absence of crystal symmetry in PLA.

Zeolitic Imidazolate Frameworks Serve as an Interface Layer for Designing Bifunctional Bone Scaffolds with Antibacterial and Osteogenic Performance

The integration of hydroxyapatite (HA) with broad-spectrum bactericidal nano-silver within biopolymer-based bone scaffolds not only promotes new bone growth, but also effectively prevents bacterial infections. However, there are problems such as a poor interface compatibility and easy agglomeration. In this project, zeolitic imidazolate frameworks (ZIF-8) were grown in situ on nano-HA to construct a core–shell structure, and silver was loaded into the ZIF-8 shell through ion exchange. Finally, the core–shell structure (HA@Ag) was composited with polylactic acid (PLLA) to prepare bone scaffolds. In this case, the metal zinc ions of ZIF-8 could form ionic bonds with the phosphate groups of HA by replacing calcium ions, and the imidazole ligands of ZIF-8 could form hydrogen bonds with the carboxyl groups of the PLLA, thus enhancing the interface compatibility between the biopolymers and ceramics. Additionally, the frame structure of MOFs enabled controlling the release of silver ions to achieve a long-term antibacterial performance. The test results showed that the HA@Ag nanoparticles endowed the scaffold with good antibacterial and osteogenic activity. Significantly, the HA@Ag naoaprticle exhibited a good interfacial compatibility with the PLLA matrix and could be relatively evenly dispersed within the matrix. Moreover, the HA@ZIF-8 also effectively enhanced the mechanical strength and degradation rate of the PLLA scaffold.

Mineralized Collagen/Polylactic Acid Composite Scaffolds for Load-Bearing Bone Regeneration in a Developmental Model.

Repairing load-bearing bone defects in children remains a big clinical challenge. Mineralized collagen (MC) can effectively simulate natural bone composition and hierarchical structure and has a good biocompatibility and bone conductivity. Polylactic acid (PLA) is regarded as a gold material because of its mechanical properties and degradability. In this study, we prepare MC/PLA composite scaffolds via in situ mineralization and freeze-drying. Cell, characterization, and animal experiments compare and evaluate the biomimetic properties and repair effects of the MC/PLA scaffolds. Phalloidin and DAPI staining results show that the MC/PLA scaffolds are not cytotoxic. CCK-8 and scratch experiments prove that the scaffolds are superior to MC and hydroxyapatite (HA)/PLA scaffolds in promoting cell proliferation and migration. The surface and interior of the MC/PLA scaffolds exhibit rich interconnected pore structures with a porosity of ≥70%. The XRD patterns are typical HA waveforms. X-ray, micro-CT, and H&E staining reveal that the defect boundary disappears, new bone tissue grows into MC/PLA scaffolds in a large area, and the scaffolds are degraded after six months of implantation. The MC/PLA composite scaffold has a pore structure and composition similar to cancellous bone, with a good biocompatibility and bone regeneration ability.