Page 10 - IJB-9-6

International Journal of Bioprinting Electrospinning PETG

diameter decreases monotonically by increasing the biosensor. Puccinia striiformis f. sp. tritici is a causative
distance from the tip . Afterward, the jet starts to coil and fungal pathogen that causes wheat yellow rust, which is
[5]
undergo bending instabilities that further reduces the fiber currently a global epidemic responsible for reduction in the
diameter. Fibers produced by electrospinning presents a wheat yield. Using sensing systems to detect such diseases
large control over the fiber diameters, ranging from nano- can help in taking preventative actions to reduce its effect.
to micro-meters [8,9] . These fibers compared to microfibers In this work, we also investigated for the first-time
produced by other conventional spinning techniques, producing PETG meshes via electrospinning, investigated
including melt spinning, dry spinning, and wet spinning, effects of different solvent splits on meshes quality, and
have significantly reduced diameters, thus increasing the optimized the electrospinning process parameters.
specific surface area of the produced structures [10,11] . These Electrospinning is used as a proof of concept for future
distinctive features led to electrospinning being used for production of PETG meshes using more advanced
a range of applications such as support structures for techniques such as electrohydrodynamic printing (EHDP) .
[25]
cell attachment, proliferation, and differentiation [5,6,12,13] , Furthermore, the meshes bioactivity was assessed by growing
wound dressings [14,15] , and sensing membranes [16,17] . yellow rust spores to prove the concept of usage in sensing
Electrospinning was reported to be a viable technique for systems.
the encapsulation of cells, thus allowing the fabrication
of cell-laden structures [18,19] . Modular systems, combining 2. Materials and methods
solution electrospinning and other additive manufacturing
techniques such as extrusion, have been also proposed for 2.1. Materials
the fabrication of hierarchical constructs [4,20,21] . In this work, Polymeric electrospun meshes were produced using
electrospinning is investigated as a potential technology PETG with molecular weight of 300 g/mol purchased
to produce the upper layer of the proposed biosensor for from RS components (Northants, UK). Solutions were
the early detection of yellow rust. The proposed biosensor prepared using acetic acid (AA; glacial, ACS reagent
consists of three layers, where the first layer imitates the ≥99.7%), acetone (ACE; ACS reagent ≥99.5%), ethanol
morphology of wheat leaf, the second layer is the substrate (ETH; 98%), dimethyl sulfoxide (DMSO; ACS reagent
layer where sucrose and agar are used as a feeding media for ≥99.9%), dimethylformamide (DMF; ACS reagent
the germinate spore, and finally the third layer is made up of ≥99.8%), tetrahydrofuran (THF; ACS reagent ≥99.0%),
a nonenzymatic glucose sensor which is used to detect the dichloromethane (DCM; containing 40-150 ppm amylene
glucose produced by the interaction between the invertase as stabilizer, ACS reagent, ≥99.5%), and trifluoroacetic acid
produced by the germinated spores and the substrate (TFA; 99%), which were all purchased from Sigma Aldrich
layer . As electrospinning allows to produce meshes (Dorset, UK).
[22]
with high surface area, this will increase the capability to
support pathogen inoculation and germination. 2.2. Mapping spinnability–solubility of PETG on the
Teas graph
In previous work, it was also shown that polyethylene The solubility of PETG in the different solvents was
terephthalate glycol (PETG) is an ideal material for the investigated using the Teas graph to identify the fractional
fabrication of the upper layer due to its shape changing cohesion parameters of solvents (hydrogen bonding, polar
properties, biodegradability, and ability to support cell force, and dispersion force) [26-29] . Solubility was tested at
attachment and proliferation, suggesting a similar behavior 20% w/v polymer concentration, atmospheric pressure,
regarding the yellow rust [23,24] . However, PETG has low and room temperature (20°C). Briefly, 2 g of PETG were
solubility in most solvents, which are also usually highly added to 10 mL of single solvent systems (AA, ACE, ETH,
volatile, making it difficult for electrospinning. DMSO, DMF, THF, DCM, or TFA) and binary solvent
In this study, we investigated for the first-time the systems (DCM/DMF, DCM/AA, DCM/THF, or DCM/
fabrication of electrospun PETG meshes. A preliminary TFA). The mixture was stirred with a magnetic stirring
study on the solubility and electrospinnability of PETG bar at room temperature. The process was visually assessed
using a range of solvent systems was conducted, and a Teas after 1 h, 2 h, and 4 h. Then, solubilities were categorized
graph was established to select the ideal solvent system. as insoluble (no dissolution), partially soluble (dissolution
Based on these preliminary results, electrospun PETG achieved but at lower rate or lower capacity), and soluble
fibers were produced and extensively characterized. The (quick and complete dissolution), based on the time to
results also demonstrated for the first time the ability of form a homogeneous solution. The binary solvent systems
electrospun PETG meshes to support the inoculation were also identified and calculated using the lever rule
[30]
and germination of yellow rust spores, thus confirming assuming 1:1 ratio . Finally, the solubility results of the
that PETG is an ideal material to be used in the proposed binary solvent systems were compared to the single solvent

Volume 9 Issue 6 (2023) 2 https://doi.org/10.36922/ijb.0024