Electrospun bone scaffolds are widely studied because they can reproduce key structural features of the native extracellular matrix while supporting cell attachment, proliferation, and tissue regeneration. For bone tissue engineering, that means designing scaffold membranes that are not only bioactive, but also mechanically suitable under conditions that better reflect real biological use.
In this study, researchers from McMaster University and the Federal University of Pelotas developed electrospun PCL/gelatin membranes loaded with hydroxyapatite and niobium pentoxide for bone repair applications. CellScale contributed to the work through the use of the UniVert, which was used to perform tensile testing on the membranes under both dry and hydrated conditions. That testing helped show how the membranes behaved mechanically in a more physiologically relevant setting while the rest of the study examined morphology, bioactivity, degradation, and cell response.
For broader background on why this matters, see our guide to mechanical testing of biomaterials.
Why electrospun bone scaffolds are useful in bone tissue engineering
The goal of electrospun bone scaffolds is to create a fibrous structure that more closely resembles the architecture of native bone extracellular matrix. Electrospinning is especially attractive because it can produce micro- to nanoscale fibers with high surface area and porosity, both of which are useful for cell interaction and tissue integration. In bone tissue engineering, scaffold design also needs to account for degradation, surface bioactivity, and mechanical properties so that the material can support tissue formation without failing too early.
This is why the present study is so useful. It does not focus on just one property. Instead, it looks at how particle-loaded membranes behave mechanically, chemically, and biologically, which gives a much more complete view of their potential as bone tissue engineering membranes.
Why the researchers chose PCL, gelatin, hydroxyapatite, and niobium pentoxide
The membrane base was made from polycaprolactone and gelatin. This is a sensible pairing for electrospun PCL gelatin membranes because PCL offers bioresorbability and structural support, while gelatin improves hydrophilicity and biological interaction. The paper notes that PCL and gelatin have already shown value in biomedical applications and that the combination can help overcome limitations of each polymer when used alone.
SEM and TEM images of niobium pentoxide and hydroxyapatite particles used in the electrospun membrane formulation.
Hydroxyapatite was added because of its chemical similarity to bone and its known bioactivity. Niobium pentoxide was included because of its reported biocompatibility and its potential to support cell adhesion, differentiation, and apatite formation. Together, these additions were intended to improve the biological performance of the membrane without compromising its scaffold structure.
What the researchers made
The team fabricated composite membranes by electrospinning PCL/gelatin with hydroxyapatite and different levels of niobium pentoxide. The resulting membranes had uniform, bead-free, randomly distributed fibers, and the incorporation of particles did not significantly disrupt fiber morphology. That is an important result for electrospun bone scaffolds, because it shows that particle loading can be integrated into the scaffold without losing the fibrous architecture that makes electrospinning attractive in the first place.
The authors also observed that the membranes remained hydrophilic after the addition of particles, which is useful because surface wettability can influence how cells interact with a biomaterial. In practical terms, the membranes combined a favorable fibrous structure with biologically relevant surface behaviour.
For a related materials-focused read, see our post on chitosan-halloysite hydrogel composites.
How the CellScale UniVert was used
CellScale’s role in the study came through the UniVert, which was used for tensile testing of electrospun membranes. Rectangular specimens were tested under both dry conditions and wet conditions after immersion in PBS. The researchers measured tensile strength, Young’s modulus, and elongation at break to compare how the membranes behaved mechanically across compositions and environments.
Hydrated mechanical testing revealed the most important tensile result
One of the clearest takeaways from the study is that the addition of hydroxyapatite and niobium pentoxide did not significantly change tensile strength, Young’s modulus, or elongation at break when comparing the different membrane groups directly. However, there were significant differences between dry and wet conditions across the membranes. Once hydrated, tensile strength, stiffness, and elongation all decreased noticeably.
In vitro and in vivo, scaffold membranes are not used in a dry state. Their performance in fluid matters. This study shows that even when particle loading does not strongly change dry-versus-dry comparisons between formulations, hydration itself has a major effect on scaffold mechanics.
The membranes also showed useful biological performance
The study did more than measure mechanics. It also showed that the particle-containing membranes supported bioactivity and cell response. When the membranes were soaked in simulated body fluid, the particle-loaded groups promoted hydroxyapatite formation on the surface, while the particle-free control did not show the same response. This indicates that the added hydroxyapatite and niobium pentoxide improved the membrane’s ability to support mineral-like surface formation.
Saos-2 cells adhered to the electrospun membrane, showing healthy morphology and filopodia extending into the scaffold network.
The biological data were also promising. Saos-2 cells showed increasing metabolism over time on all membranes, and the niobium-containing groups were non-cytotoxic while supporting cell proliferation and differentiation-related activity. Among the tested groups, the PGHANb-7 membrane performed especially well at later time points.
These findings strengthen the case that the membranes are not just structurally interesting, but potentially useful as bone repair membranes with both bioactive and cell-supportive properties.
Why degradation and bioactivity matter alongside mechanics
A scaffold for bone tissue engineering has to do more than survive an initial pull test. It should also degrade at a useful rate and promote mineralization-related behaviour. In this work, membranes with higher particle loading showed slower degradation than the particle-free controls, which may be beneficial when the goal is to provide the scaffold with enough residence time to support extracellular matrix formation and new bone growth.
That balance is one of the reasons this paper is valuable. It shows that electrospun bone scaffolds can be tuned not just for one outcome, but for a combination of structural, mechanical, and biological properties.
What this means for bone tissue engineering
The broader takeaway is that these particle-loaded PCL/gelatin membranes are promising candidates for bone regeneration because they combine several desirable features: electrospun fibrous architecture, hydrophilic surfaces, preserved scaffold mechanics, improved bioactivity, and encouraging cell response. The mechanical data also add an important note of realism by showing how much hydrated conditions can affect performance.
For researchers developing mechanical properties of bone tissue engineering scaffolds, that is an important reminder. Materials should not only be compared across formulations. They should also be tested in conditions that better approximate how the scaffold will actually be used.
Final thoughts
This study makes a strong case for electrospun bone scaffolds based on PCL/gelatin membranes loaded with hydroxyapatite and niobium pentoxide. The membranes retained a uniform fibrous structure, showed improved bioactivity and cell compatibility, and were mechanically characterized using the CellScale UniVert under both dry and hydrated conditions.
The most practical message is that hydrated testing matters. Even when different particle-loaded groups do not show large statistical differences against one another, the shift from dry to wet conditions clearly changes scaffold mechanics. For bone tissue engineering, that makes tensile testing of electrospun membranes under physiologically relevant conditions especially valuable.
Read the full publication here: Niobium pentoxide and hydroxyapatite particle loaded electrospun polycaprolactone/gelatin membranes for bone tissue engineering
To learn more about the instrument used in this study, visit the CellScale UniVert.
