Biomaterials
common biopolymers used in biofabrication fields. Water and other substances used as food additives, such as acetic acid, are class Q3C. The team found a handful of green solvents
that could not only be used successfully, but that produced fibres with better material properties than those made using organic solvents. These findings are certainly promising. For industry players, they could indicate ways of working that would allow a scale-up in production; for researchers, they may work to further investigation into the sustainability and efficacy of electrospinning. But whether this green electrospinning process could become a reality beyond the lab raises a more complex set of questions: how many in the field can apply these findings to their work, and what does it realistically take for a lab process to translate into industrial manufacturing?
Applying the findings
Because the polymers investigated – collagen, polylactic-co-glycolic acid (PLGA), and polycaprolactone (PCL) – are commonly used in biomedicine, Mosher believes the findings are relevant to most electrospinning labs, and that they could inform workflows across the wider medical device industry.
“I think that almost every lab that does electrospinning uses one of these three polymers ... but there’s others within that chemical family that we think this will also apply to,” he says. “Moving forward, the idea for the industry is just to adapt to these Q3C solvents.”
While many of the Q3C solvents didn’t work with the polymers, there was a handful that did – with acetic acid coming out on top as the most effective. As well as having a low ecological impact, acetic acid can be used for electrospinning under routine fabrication conditions. Helpfully, the paper also includes information on all the parameters used when each polymer was electrospun with each solvent, which Mosher hopes that everyone in the field will use as a blueprint to inform their own work. Researchers could look through the FDA tables and try out a greener solvent, and manufacturers could use the system as a baseline method and add any necessary tweaks. “For someone who has electrospinning experience, this isn’t decades of work,” says Mosher. “You could figure this out in a few runs of electrospinning.” However, green solvents won’t always be an option as many polymers simply won’t dissolve in them. “In most cases, most materials are soluble in organic solvent, not in water or an environmentally- friendly solvent,” says associate professor of fibre science at Cornell University Dr Tamer Uyar, who
Medical Device Developments /
www.nsmedicaldevices.com How does Mosher’s green electrospinning work?
Applying sustainability principles to biomaterial production, Mosher and his team developed their ‘green’ electrospinning process by systematically testing biologically benign solvents (US Food and Drug Administration Q3C Class 3). Through trial and error, they identifi ed acetic acid as a solvent that exhibits low ecological impact (global warming potential (GWP) = 1.40 CO2
eq. kg/L) and
supports a stable electrospinning jet under routine fabrication conditions. By tuning electrospinning parameters, such as needle-plate distance and fl ow rate, the researchers updated the fabrication of widely used biomedical polymers (for example, poly--hydroxyesters, collagen), polymer blends, polymer-ceramic composites, and growth factor delivery systems. The resulting ‘green’ fi bres and composites were comparable to traditional meshes in terms of composition, chemistry, architecture, mechanical properties, and biocompatibility. Interestingly, they found the material properties of green synthetic fi bres were more biomimetic than those of traditionally electrospun fi bres, doubling in ductility without compromising yield strength or ultimate tensile strength. Most importantly, green electrospinning proves advantageous for biofabrication, rendering a greater protection of growth factors during fi bre formation and recapitulating native ECM mechanics in the fabrication of biopolymer-based meshes. Mosher and his fellow researchers on the project from Columbia University believe the eco-conscious approach they demonstrated represents a paradigm shift in biofabrication, and will accelerate the translation of scalable biomaterials and biomimetic scaffolds for tissue engineering and regenerative medicine.
is also the editor of the journal Electrospinning. “That’s the chemistry – you cannot avoid it.” However, he believes a helpful future direction for research might be to identify new materials that could be used with green solvents. These could be obtained from nature, as has been seen in electrospun PET bottles formed using plant- based reactants, rather than those from oil sources or petrol.
From lab to industry Translating a lab finding into industrial use is often a journey fraught with practical, commercial, and regulatory challenges. Even if a manufacturer did want to use Mosher’s paper as a blueprint for altering their work, any material changes to a medical device may require approval – which can come with a new set of costs.
in organic solvent, not in water or an environmentally-friendly solvent. That’s the chemistry – you cannot avoid it.”
Tamer Uyar
If there is a change in the materials used to create the device, which would include a change in solvents used during the electrospinning process, the FDA may require a risk assessment of any new or increased biocompatibility concerns. For any changes that may impact a device’s safety and effectiveness, the FDA requires that manufacturers
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