Page 365 - IJB-9-5

International Journal of Bioprinting Multifunctional hydrogel surgical training model

data in a computer. It is a comprehensive technology that material with mechanical and related physicochemical
combines CAD, computer numerical control (CNC), properties that can be selected in a wide range by
mechanical technology, and materials science with a adjusting the concentration of components and ionic
fundamental approach to the layered overlay. The CAD solution immersion strategy. By combining 3D-printing
model is divided according to a specific layer thickness technology, we designed and prepared physical models
and then printed by a 3D printer with different capabilities with various mechanical properties matching human
using particular materials. The nozzles or optics are organ tissues and used them for surgical training tests in
computer driven to form the structure on the substrate one different scenarios. It provides new strategies and solutions
layer at a time and build the complete object layer by layer. for future surgical training and medical device testing and
With the advancement of 3D printing platforms, various has broad application prospects.
in vitro 3D tissue and organ structures with complex
anatomical features, adjustable dimensions, and high 2. Materials and methods
spatial resolution can be easily and quickly constructed
through a layer-by-layer process. The team summarized 2.1. Materials
the current mainstream 3D printing technologies and the The materials used in the study include polyvinyl alcohol
materials applied to different technologies in a specific (PVA, 98–99% alcoholysis, Aladdin), acrylamide (AM,
classification. The latest technologies in organ model 99%, Aladdin), N-N’-methylene-bis-acrylamide (MBAA,
preparation and the contribution of 3D-printed organ 99%, Aladdin), ammonium persulfate (APS, >98%,
models to various surgical procedures were reviewed . In Aladdin), tetramethylethylenediamine (TEMED, ≥ 99.5%,
[19]
addition, Ng et al. made a detailed summary and evaluation Aladdin), sodium chloride (NaCl, 99.8%, Aladdin),
of extrusion, stereolithography, and inkjet printing based aqueous dyes, and deionized water. All materials were
on bio-3D printing. They provided a detailed classification bought and used directly without further purification.
overview of relevant hydrogel printing materials and
application scenarios . 2.2. Preparation of hydrogel models
[20]
The preparation of the pre-polymerization solution of the
Hydrogels also offer highly tunable mechanical model was mainly done in two parts. Firstly, PVA was
properties (stiffness, elasticity, and durability), similar to dissolved at 90°C for about 1 h until the solid powder
the strength of natural soft tissues. Such tunable properties was dissolved entirely, cooled to room temperature, and
can be used to construct 3D tissue and organ models then bottled to obtain solution A. Then, 2 M of AM was
with tissue-mimicking and mechanical characteristics. dissolved in deionized water at room temperature, and
For example, Jiang et al. achieved hydrogel-based organ 0.03–0.3 mol% of MBAA and 2 mg/mL of APS were added
human models with interconnected cavities and gradient to obtain solution B. Solution A and solution B were mixed
structures by developing metal ion-induced interfacial at a volume ratio of 1:1 and stirred evenly. Finally, 2 μL/
supramolecular assembly of hydrogel layers on 3D-printed mL TEMED solution was added dropwise to obtain the
fugitive hydrogel templates . Additionally, Wang et pre-polymerization solution. The pre-polymerization
[21]
al. used gelatin methacrylate (GelMA)/hyaluronic acid solution was injected into the 3D-printed organ molds
methacrylate (HAMA) ink and digital light processing prepared in advance through the pouring port until they
(DLP)-based 3D printing to fabricate a variety of volumetric were full. Then the whole molds filled with the solution
soft tissues with tissue-matched mechanical properties and were put into a freezer at -20°C for a cryogenic freezing
structurally complex structures . Yang et al. prepared reaction and removed from the freezer. Depending on
[22]
heterogeneous hydrogels with complex shapes and fatigue the desired conditions of the model, 1–2 cycles of freezing
resistance consisting of rigid skeletons and soft matrices were performed, and the prepared hydrogel model was
by stereolithography bio gel tissue . Nevertheless, due finally detached from the mold after room temperature was
[23]
to their weak and poor mechanical properties, most restored. For the pipeline models of the category of blood
dual-network (DN) hydrogel materials can barely meet vessels with similar fine apertures, the blood vessel models
the general modulus requirements of different tissue were obtained by printing the sacrificial material as the
and organ models . Based on this, we prepared a DN inner core, coating the surface with the pre-polymerization
[24]
hydrogel with elastic properties using polyvinyl alcohol solution, and waiting for the end of the reaction to remove
and acrylamide as the main monomer components the inner core. The various organ models obtained were
according to the general characteristics of surgery and the treated by immersion in a saturated NaCl solution of choice
physicochemical properties and structural morphology according to the requirements to get the final training
of human organs. We obtained a wet-slip hydrogel elastic model that met the performance requirements.

Volume 9 Issue 5 (2023) 357 https://doi.org/10.18063/ijb.766