An official website of the United States government
Electrospun fibrous scaffolds made from polymers such as polycaprolactone (PCL) have been used in drug delivery and tissue engineering for their viscoelasticity, biocompatibility, biodegradability, and tunability. Hydrophobicity and the prolonged degradation of PCL causes inhibition of the natural tissue-remodeling processes. Poliglecaprone (PGC), which consists of PCL and Poly (glycolic acid) (PGA), has better mechanical properties and a shorter degradation time compared to PCL. A blend between PCL and PGC called PPG can give enhanced shared properties for biomedical applications. In this study, we fabricated a blend of PCL and PGC nanofibrous scaffold (PPG) at different ratios of PGC utilizing electrospinning. We studied the physicochemical and biological properties, such as morphology, crystallinity, surface wettability, degradation, surface functionalization, and cellular compatibility. All PPG scaffolds exhibited good uniformity in fiber morphology and improved mechanical properties. The surface wettability and degradation studies confirmed that increasing PGC in the PPG composites increased hydrophilicity and scaffold degradation respectively. Cell viability and cytotoxicity results showed that the scaffold with PGC was more viable and less toxic than the PCL-only scaffolds. PPG fibers were successfully coated with polydopamine (PDA) and collagen to improve degradation, biocompatibility, and bioactivity. The nanofibrous scaffolds synthesized in this study can be utilized for tissue engineering applications such as for regeneration of human articular cartilage regeneration and soft bones.
more »
« less
Investigating the Effect of Aligned Microtube Density on the Mechanical Strength of Hydrogel Scaffolds
Abstract Tissue engineering is a pivotal research domain, central to advancing biomedical manufacturing processes with the aim of fabricating functional artificial organs and tissues. Addressing the pressing concern of organ shortages and myriad medical challenges necessitates innovative manufacturing techniques. Hydrogel scaffolds, due to their biocompatibility and extracellular matrix-mimicking porous structure, have emerged as prime candidates in this arena. Moreover, their hygroscopic properties and tunable mechanical characteristics render them suitable for various tissue engineering applications. Despite their promising attributes, a significant manufacturing challenge persists: the optimization of cellular growth within the confines of hydrogel scaffolds. Effective vascularization, essential for optimal cellular nutrient and oxygen supply, remains elusive. Our previous manufacturing research tackled this, introducing a novel hybrid Bio-Fabrication technique. This technique integrated coaxial electrospinning and extrusion-based bioprinting methodologies, yielding hydrogel scaffolds fortified with microtubes. These strategically embedded microtubes, modeled after capillary structures, function as microchannel diffusion conduits, enhancing cellular viability within the hydrogel matrix. A core aspect of scaffold manufacturing is ensuring the stability of its 3D architecture, especially post-swelling. Preliminary hypotheses suggest a gamut of factors — including microtube shape, size, orientation, alignment, and density — play determinant roles in shaping the scaffold’s mechanical attributes. This research rigorously examines the mechanical evolution of hydrogel scaffolds when supplemented with aligned electrospun microtubes across a spectrum of densities. A blend of sodium alginate (SA) and gelatin was selected for the hydrogel matrix due to their inherent biocompatibility and favorable mechanical properties. Different concentrations were prepared to assess the optimal mixture for mechanical stability. A co-axial electrospinning setup was employed where polycaprolactone (PCL) was used as the sheath material and polyethylene oxide (PEO) functioned as the core. This dual material approach was intended to leverage the structural rigidity of PCL with the biodegradability of PEO. The spinning parameters, including voltage, flow rate, and tip-to-collector distance, were meticulously adjusted to produce aligned microtubes of varied densities and diameters. Once the microtubes were synthesized, they were layered within the hydrogel constructs. The layering process involved depositing a hydrogel layer, positioning the microtubes, and then sealing with another hydrogel layer. The entire structure was then solidified using calcium chloride, resulting in a robust, multi-layered composite. Post-fabrication, the hydrogel scaffolds underwent mechanical evaluations. Compression tests were employed to measure the compressive modulus. Tensile tests were conducted to determine ultimate tensile strength. These tests were crucial to understanding the impact of microtube density on the overall mechanical properties of the hydrogel scaffolds. The high-density group, while showing improved mechanical properties over the control group, did not surpass the low-density group, suggesting a possible saturation point. In conclusion, our research methodically explored the influence of microtube density on the mechanical and structural attributes of hydrogel scaffolds. The manufacturing insights gleaned hold substantive implications, promising to propel the field of tissue engineering and drive transformative advancements in biomedical manufacturing.
more »
« less
- Award ID(s):
- 2528265
- PAR ID:
- 10585433
- Publisher / Repository:
- American Society of Mechanical Engineers
- Date Published:
- ISBN:
- 978-0-7918-8810-0
- Format(s):
- Medium: X
- Location:
- Knoxville, Tennessee, USA
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Electrospinning has been used to create scaffolds with tunable micro/nano architecture, stiffness, and porosity to mimic native extracellular matrix. This study investigated the effects of electrospinning parameters and hydrogel formulation (solvent and crosslinker type) on the architecture and properties of fibrous poly(ethylene glycol) (PEG) hydrogels formed from a photoclick thiol‐norbornene reaction. Fibrous hydrogels were prepared using hydrogel precursors (four‐arm PEG norbornene and multi‐thiol crosslinker), sacrificial poly(ethylene oxide) (PEO, 400 kDa), and photoinitiator (I2959) in either 2,2‐triflouroethanol (TFE) or water. Three thiol crosslinkers‐ 2,2′‐(ethylenedioxy)diethanethiol (EDT), pentaerythritol tetrakis(3mercaptopropionate) (PTMP), and PEG dithiol (PEGDT)‐ were investigated. Fibrous PEG networks with uniform fibers were produced at applied voltages of 10 or 12 kV for TFE and 16 kV for water. Fiber diameters of electrospun hydrogels were largely affected by the solvent when combined with PEO concentration and ranged from 0.5 to 3.5 mm in dry state. While the effect of crosslinker type on fiber diameter, morphology, and porosity of the fibrous hydrogel was minimal, it did modulate its shear modulus. To this end, this study provides the groundwork for selecting processing parameters to achieve desired properties of fibrous PEG thiol‐norbornene hydrogels for intended tissue engineering applications ranging from neural, cardiovascular to musculoskeletal.more » « less
-
Abstract With the increasing interest in biopolymer nanofibers for diverse applications, the characterization of these materials in the physiological environment has become of equal interest and importance. This study performs first‐time simulated body fluid (SBF) degradation and tensile mechanical analyses of blended fish gelatin (FGEL) and polycaprolactone (PCL) nanofibrous meshes prepared by a high‐throughput free‐surface alternating field electrospinning. The thermally crosslinked FGEL/PCL nanofibrous materials with 84–96% porosity and up to 60 wt% PCL fraction demonstrate mass retention up to 88.4% after 14 days in SBF. The trends in the PCL crystallinity and FGEL secondary structure modification during the SBF degradation are analyzed by Fourier transform infrared spectroscopy. Tensile tests of such porous, 0.1–2.2 mm thick FGEL/PCL nanofibrous meshes in SBF reveal the ultimate tensile strength, Young's modulus, and elongation at break within the ranges of 60–105 kPa, 0.3–1.6 MPa, and 20–70%, respectively, depending on the FGEL/PCL mass ratio. The results demonstrate that FGEL/PCL nanofibrous materials prepared from poorly miscible FGEL and PCL can be suitable for selected biomedical applications such as scaffolds for skin, cranial cruciate ligament, articular cartilage, or vascular tissue repair.more » « less
-
Abstract Engineered composite scaffolds composed of natural and synthetic polymers exhibit cooperation at the molecular level that closely mimics tissue extracellular matrix's (ECM) physical and chemical characteristics. However, due to the lack of smooth intermix capability of natural and synthetic materials in the solution phase, bio‐inspired composite material development has been quite challenged. In this research, we introduced new bio‐inspired material blending techniques to fabricate nanofibrous composite scaffolds of chitin nanofibrils (CNF), a natural hydrophilic biomaterial and poly (ɛ‐caprolactone) (PCL), a synthetic hydrophobic‐biopolymer. CNF was first prepared by acid hydrolysis technique and dispersed in trifluoroethanol (TFE); and second, PCL was dissolved in TFE and mixed with the chitin solution in different ratios. Electrospinning and spin‐coating technology were used to form nanofibrous mesh and films, respectively. Physicochemical properties, such as mechanical strength, and cellular compatibility, and structural parameters, such as morphology, and crystallinity, were determined. Toward the potential use of this composite materials as a support membrane in blood–brain barrier application (BBB), human umbilical vein endothelial cells (HUVECs) were cultured, and transendothelial electrical resistance (TEER) was measured. Experimental results of the composite materials with PCL/CNF ratios from 100/00 to 25/75 showed good uniformity in fiber morphology and suitable mechanical properties. They retained the excellent ECM‐like properties that mimic synthetic‐bio‐interface that has potential application in biomedical fields, particularly tissue engineering and BBB applications.more » « less
-
In this work, electrospun polyvinylidene-trifluoroethylene (PVDF-TrFE) was utilized for its biocompatibility, mechanics, and piezoelectric properties to promote Schwann cell (SC) elongation and sensory neuron (SN) extension. PVDF-TrFE electrospun scaffolds were characterized over a variety of electrospinning parameters (1, 2, and 3 h aligned and unaligned electrospun fibers) to determine ideal thickness, porosity, and tensile strength for use as an engineered skin tissue. PVDF-TrFE was electrically activated through mechanical deformation using low-intensity pulsed ultrasound (LIPUS) waves as a non-invasive means to trigger piezoelectric properties of the scaffold and deliver electric potential to cells. Using this therapeutic modality, neurite integration in tissue-engineered skin substitutes (TESSs) was quantified including neurite alignment, elongation, and vertical perforation into PVDF-TrFE scaffolds. Results show LIPUS stimulation promoted cell alignment on aligned scaffolds. Further, stimulation significantly increased SC elongation and SN extension separately and in coculture on aligned scaffolds but significantly decreased elongation and extension on unaligned scaffolds. This was also seen in cell perforation depth analysis into scaffolds which indicated LIPUS enhanced perforation of SCs, SNs, and cocultures on scaffolds. Taken together, this work demonstrates the immense potential for non-invasive electric stimulation of an in vitro tissue-engineered-skin model.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/MSEC2024-125393
