Page 182 - IJB-9-3

International Journal of Bioprinting Chitin/gelatin/PVA scaffolds

assessed as an alternative source for chitin extraction. formation . Both macro- and micro-porosity, as well
[23]
C. capitata causes indirect economic losses in fruit as interconnectivity between pores, are required [23,24] . To
production and thus, different strategies are employed address all these challenges, the combination of 3DP and
for an integrated pest management of fruit flies, such as ES is carried out in this work, using both techniques in a
the sterile insect technology, in which large quantities of sequential mode to get a sandwich-type hybrid structure.
pupae are generated . These pupae represent a source of Although some works have been carried out with chitosan
[4]
chitin, since this polysaccharide with unique technological and gelatin inks [25,26] , the incorporation of chitin into
properties is the major organic component in pupae gelatin-based ink is a novel approach to improve cellular
(around 86% of the total weight) . Chitin is the second adhesion and protect cells from bacterial colonization.
[5]
most abundant polysaccharide in nature and it has a long In this work, a complete assessment was carried out,
history of scientific studies, such as those for biomedical from the optimization of the chitin extraction to the
applications . Moreover, chitin can be employed to characterization of the final scaffolds to evaluate their
[6]
enhance the functional properties of other biopolymers, viability for biomedical applications.
such as gelatin, which can also be extracted from
biowastes [7,8] . 2. Materials and methods
Several technologies have been employed to obtain 2.1. Materials
products from available, zero-cost, and biodegradable Porcine gelatin (250 bloom) was supplied by Sancho de
wastes ; among them, 3D printing (3DP) and Borja SL (Spain). Chitin was extracted from the fruit fly
[9]
electrospinning (ES) have been utilized . On the one pupae (C. capitata), which were supplied by TRAGSA
[10]
hand, 3DP techniques are known since 1986, when Charles (Spain). Glycerol (99.01% purity) and acetic acid were
Hull introduced 3D lithography technology . This obtained from Panreac (Spain), and PVA was provided
[11]
technology never cease to develop and provide solutions by Sigma-Aldrich (USA). NaOH and H O employed for
in different sectors, such as automotive, aerospace, dental, the chitin extraction were purchased from Panreac (Spain)
2
2
and biomedical fields; sometimes, it is used to obtain and Honeywell (Germany), respectively.
prototypes and final parts [12-14] . Nowadays, 3DP techniques
are gaining interest because of their unique capacity to 2.2. Sample preparation
deposit biological and non-biological components to 2.2.1. Extraction of chitin from fruit fly pupae
mimic the extracellular matrix and provide the required The chitin extraction procedure followed in this work
microenvironment to ensure cell adhesion, migration, was selected based on previous experiments in order to
and replication [15,16] . In this regard, adding chitin to optimize the yield and increase the resources efficiency,
gelatin-based inks can lead to the formulation of inks with both environmental and economical. Hence, in this
enhanced properties, such as good adhesion performance, work, 50 g of fruit fly pupae were washed with water to
biological compatibility, and appropriate biodegradability remove impurities and treated with NaOH (1 M) at room
rate , with potential for wound healing applications . temperature for 24 h under continuous stirring. Then,
[18]
[17]
On the other hand, ES is a technique to obtain nano- and/ samples were filtered and the solid fraction (chitin) was
or micro-fibers with high area/volume ratio via an electric washed with distilled water up to neutral pH. Prior to use,
field [19,20] . High voltage and constant feed rate are applied chitin was decolored with H O in a ratio of 1:20 (w/v) at
to a polymer solution, making the electrostatic repulsion room temperature for 2 h. The mixture was filtered and the
2
2
force overcome surface tension, and ejecting the polymer solid fraction was dried in an oven at 40°C for 24 h. Finally,
solution to the ground. In this process, the solvent is chitin was milled to obtain the powder.
evaporated and the polymer is deposited to form a porous
mat. In this regard, poly(vinyl alcohol) (PVA) is frequently 2.2.2. 3DP ink preparation
blended with other polymers, such as gelatin or sodium 3DP ink was prepared by dissolving 8 wt% gelatin in
alginate, in order to ensure the spinnability of natural distilled water together with 5 wt% chitin (based on gelatin
polymers due to its water solubility, biocompatibility, and mass) and 30 wt% glycerol (based on gelatin mass). The
biodegradability . mixture was kept at 85°C under constant stirring for
[19]
Taking the above into consideration, chitin/ 30 min. Then, the pH was adjusted to 7 with NaOH (1 M)
gelatin/PVA scaffolds were prepared in this work and the sample was stirred at 8000 rpm for 300 s with
for biomedical applications. Since scaffolds should an IKA S 25N-18G-ST ULTRA-TURRAX homogenizer
replicate the morphology and the function of target (IKA-Werke, Germany) using a 18 mm head. Finally,
tissue [21,22] , morphology requirements are related to the mixtures were poured into 3D printing syringes and stored
scaffold porosity, a limiting factor to ensure new tissue in a fridge at 4°C until further analysis.

Volume 9 Issue 3 (2023) 174 https://doi.org/10.18063/ijb.701