Page 250 - IJB-10-4

International Journal of Bioprinting Cell viability in printing structured inks

 rv = rv mm, hepatic lobule analogue-like inks with r of 1.65 mm,
′
2
2
3
 1 in 1 out1 r of 2.575 mm, and φ of 13.3°, as well as core–shell inks
4
 [( r + ) 2 − rv =] [( r′+ r′ −) 2 r ′ 2 v ] with a core layer radius of 3.1 mm.
2
r
 1 2 1 in 1 2 1 out2 (I)
 4 [ ..795 − r ) ]v = [ .042 − ′+ ′ r )]v 2.4. Comparing structured ink-based printing with
( + r
2
2
2
2
(r
 1 2 in 1 2 out 3
 1 ′ r = 1 ′ r = 2 conventional printing
 ′ r . 042 − ′′− ′ r The small nozzle size of conventional printing allows for
r
 2 1 2 the construction of high-resolution structures by adjusting
processing parameters to ensure that the extruded fiber
diameter is close to the needle inner diameter. However, this
approach often results in significant cell death. Therefore,
3 ì
2
rv 3 in = ¢ 2 4 r v
2
ì
ï rv out 2 ¢ 4 r v é in = we sought to determine whether structured ink-based
ï ï 3 3 out 2pj 0.42 2 - 0.42 sin cosj j + ù
2
ï ï ê 360 é 0.42 2 ú ù printing offers advantages over conventional printing. To
ú
2
ï ê 2pj - 0.42 sin cosj j +
0.42sinj
p
é 4.795 2 ù ï ï ê 2 R 2 ê 360 ú ú
ê
ê 2pj 360 ( 3 r + 4 r- )sinj * 4.795 v ú ï ï in = ê 360 * arctan R 0.42cosj r¢ 4 r ¢ ú v- 6 out ú control variables and facilitate comparisons, conventional
p
ï ë 4.795 2 û ê é ê 2 R - 2 3 ++ 0.42sinj ú ù ï ú printing also used 3-mL cartridges. A 32G needle with
r¢
¢ *
0.42cosj4.795 v
)*0.42sinj
ï ê ( 3 r + 4 r- )sinj * (R ê 2pj ú ï - = ê 3 r ++ arctan ú ú v- 6 out
in
ú
ï ë 360 ê ë û 360 R - 0.42cosj 3 ++ r¢ 4 r ¢
ï ï ê û ú an inner diameter of 0.1 mm was utilized to extrude
ï ì 2 2 é 4.795 2 (R ê - ù ï ï ü ï 0.42cosj 3 r ++ r¢ ¢ )*0.42sinj ú
ï ï í p * 4.795 - p 3 r - 6* ê 2pj ( 3 r + 4 r- )sinj * 4.795 ý ê in v ú = ú homogeneous inks, aiming to achieve a print resolution
ï ï ë 36 0 ë û ï î þ û
í ï for vascular-like tissue structures, while a 27G nozzle with
ï ì ï ì é 2pj é 0.42 2 - 4.795 2 ù ü ù ï ü ï
2
j
ï
ú 6*
2
ï p * ï ï í 4.795 - p 3 r - 2 ê 360 2pj 0.42 sin cosj + r + 4 r- )sinj * 4.795 ý in v = an inner diameter of 0.21 mm was used for hepatic lobule
ï ï ï ï ê 2ë ê 36 0 ( 3 ú ï ú û ï (II)
p ï
ï 2 2 ê 2 R 0.42sinj ú ï î ý í þ analogue-like tissue structures. The resolution is equivalent
ï í p 0.42 - p * 3 6* ê 360 é * arctan R - 2 0. 42cosj ¢ - ú v¢ - out 5 r
ï ï ï ê 0.42 2 3 r ++ 4 r¢ ú ï ì ù ü
j
ï ï
ï ï ï (R ê - ê 0.42cosj 2pj 360 3 r ++ r¢ ¢ - 0.42 sin cosj + ú ï to that of structured ink-based printing accomplished
ú
)*0.42sinj
ï ï ï ï ê ê ú ï ú ï using an 18G nozzle. The height of all structured inks and
ï ï î ë ê 2p ï 2 2 R 0.42sinj û þ ú ï
2
0.42cosj + 3 r p *
ï p (R - 0.42 - r¢ ) ¢+ r 2 2 + 6* (0.42*sin )j arctan - v¢ 5 -
*
2
R =
ï ï í 3 ê 360 R - 0. 42cosj 3 r ++ 4 r¢ ¢ ú ý out homogeneous inks used in conventional printing was set to
ï ï 4 r¢ ï = 5 r¢ = 0.42sin(30°- j） ê = 2 ú ï
3 î ï r 3 r ï ¢ ï ¢ 0.42 3 -- r¢ ¢ 4 r (R ê - 0.42cosj 3 r ++ r¢ ¢ )*0.42sinj ú ï the same. The steps involved in this process are as follows:
ï ï ê ú ï First, the fluid models for both conventional printing and
ï î ë û þ (II)
ï (R - 0.42cosj + 3 r r¢ ) ¢+ 2 + (0.42*sin )j 2 R = 2 structured ink-based printing were modeled, considering
ï
5 r¢
4 r¢
1 r rn(30°-
0.42si
where the terms , , , , and represent the respective geometric parameters of the cartridge and nozzle specifications for CFD simulations
ï
2 r
3 r j）
j
2
4
ï 3 î = r ¢ 3 r ¢ = 0.42 r¢ 4 r -- ¢ = (Figure 2). Fluid forces, including pressure, wall shear
3
corresponding material phases of structured inks, and 1 r ¢ r ¢ r ¢ r ¢ r ¢ , and R denote stress, and shear stress at material phase interfaces, were
, 5
, 2
, 4
, 3
(II)
where the terms r , r , r , r , and φ represent the
the respective geometric parameters of the corresponding material phases of extruded compared by calculating and analyzing the models in
2
3
1
4
respective geometric parameters of corresponding material structured ink-based printing alongside their counterparts
, v
, v
, v
,
, v
represents the inlet velocity, while v
inks. In addition, v
3
out
out
in
5
out
out
4
1
out
2
2 r
3 r
where the terms , , , , and represent the respective geometric parameters of
j
1 r r
′ ′′ ′′
4
and vses of structured inks, and rr rr r,, ,,
5 , and R denote
pha out 6 denote the respective outlet velocities of corresponding material phases. in conventional printing. This analysis also considered the
4
3
2
1
corresponding material compositions for both methods.
the respective geometric parameters of the corresponding denote
corresponding material phases of structured inks, and 1 r ¢ r ¢ r ¢ r ¢ r ¢
, and R
, 3
, 5
, 2
, 4
material phases of extruded inks. In addition, v represents 2.5. Equivalent analysis of structured inks
The dimensions of vascular-like structured inks and hepatic lobule analogue-like
in
the respective geometric parameters of the corresponding material phases of extruded
the inlet velocity, while v out1 , v out2 , v out3 , v out4 , v out5 , and v out6 In comparison to conventional printing, the use of
inks were determined by analyzing the material phase distribution of the extruded fibers
denote the respective outlet velocities of corresponding , v , v structured inks for printing, while targeting the same
inks. In addition, v
represents the inlet velocity, while v
,
, v
through CFD simulation. All models were designed using NX 10.0 (Siemens PLM , v
material phases. in out 1 out 2 out 3 out 4 out 5
Software, USA). All prepared structured inks were placed in 3-mL cartridges. So, the structural features, involves larger nozzle sizes. However,
and v denote the respective outlet velocities of corresponding material phases.
6
out
The dimensions of vascular-like structured inks and the process of preparing such inks is complex. The
hepatic lobule analogue-like inks were determined by procedure for evaluating cell viability occurs after ink
The dimensions of vascular-like structured inks and hepatic lobule analogue-like
12

analyzing the material phase distribution of the extruded preparation and structure construction. Hence, we aimed
fibers through CFD simulation. All models were designed to assess cell viability theoretically by calculating the fluid
inks were determined by analyzing the material phase distribution of the extruded fibers
using NX 10.0 (Siemens PLM Software, USA). All forces experienced by cells. This calculation was based
through CFD simulation. All models were designed using NX 10.0 (Siemens PLM
prepared structured inks were placed in 3-mL cartridges. on the premise that the fluid forces acting on cells within
So, the outer diameter of the cross-section of all structured homogeneous inks were approximately equal to those in
Software, USA). All prepared structured inks were placed in 3-mL cartridges. So, the
inks was 4.795 mm. It is essential to ensure that the structured inks. Additionally, to control variables, we used
volume flow rates at the fluid inlet and outlet are equal. an 18G nozzle and maintained the same flow velocity for
This requirement pertains to the comparative analysis of equivalent analysis as in the E3DP process with structured
12

vascular-like and hepatic lobule analogue-like inks (Figure inks. Since this is a case study, the height of the equivalent
S1 in Supplementary File), and it can be achieved by homogeneous inks was also set at 30 mm.
satisfying Equations I and II. The model parameters are as The specific steps were as follows: firstly, fluid models,
follows: symmetric inks, 2-symmetric inks, 4-symmetric including symmetric and core–shell ink-based models,
inks, vascular-like inks with r of 3.1 mm and r of 1.155
1 2 along with models for analyzing their equivalent targeting,
Volume 10 Issue 4 (2024) 242 doi: 10.36922/ijb.2362