Bioceramics with porous microstructure has attracted intense attention in tissue engineering due to tissue growth facilitation in the human body. In the present work, a novel manufacturing process for producing hydroxyapatite (HA) aerogels with a high density shell inspired by human bone microstructure is proposed for bone tissue engineering applications. This method combines laser processing and traditional freeze casting, in which HA aerogel is prepared by freeze casting and aqueous suspension prior to laser processing of the aerogel surface with a focused CO2 laser beam that forms a dense layer on top of the porous microstructure. Using the proposed method, HA aerogel with dense shell was successfully prepared with a microstructure similar to human bone. The effect of laser process parameters on the surface, cross-sectional morphology and microstructure was investigated in order to obtain optimum parameters and has a better understanding of the process. Low laser energy resulted in a fragile thin surface with defects and cracks due to the thermal stress induced by the laser processing. However, increasing the laser power generated a thicker dense layer on the surface, free of defects. The range of 40–45 W laser power, 5 mm/s scanning speed, spot size of 1 mm, and 50% overlap in laser scanning the surface yielded the best surface morphology and microstructure in our experiments.

References

References
1.
Wegst
,
U. G.
,
Bai
,
H.
,
Saiz
,
E.
,
Tomsia
,
A. P.
, and
Ritchie
,
R. O.
,
2015
, “
Bioinspired Structural Materials
,”
Nat. Mater.
,
14
(
1
), pp.
23
36
.
2.
Hing
,
K. A.
,
2004
, “
Bone Repair in the Twenty-First Century: Biology, Chemistry or Engineering?
,”
Philos. Trans. R. Soc., A
,
362
(
1825
), pp.
2821
2850
.
3.
Glimcher
,
M. J.
,
2006
, “
Bone: Nature of the Calcium Phosphate Crystals and Cellular, Structural, and Physical Chemical Mechanisms in Their Formation
,”
Rev. Mineral. Geochem.
,
64
(
1
), pp.
223
282
.
4.
Suchanek
,
W.
, and
Yoshimura
,
M.
,
1998
, “
Processing and Properties of Hydroxyapatite-Based Biomaterials for Use as Hard Tissue Replacement Implants
,”
J. Mater. Res.
,
13
(
1
), pp.
94
117
.
5.
Qiang
,
F.
,
Mohamed
,
N. R.
,
Fatih
,
D.
, and
Bal
,
B. S.
,
2008
, “
Freeze-Cast Hydroxyapatite Scaffolds for Bone Tissue Engineering Applications
,”
Biomed. Mater.
,
3
(
2
), p.
025005
.
6.
Deville
,
S.
,
Saiz
,
E.
, and
Tomsia
,
A. P.
,
2006
, “
Freeze Casting of Hydroxyapatite Scaffolds for Bone Tissue Engineering
,”
Biomaterials
,
27
(
32
), pp.
5480
5489
.
7.
Fu
,
Q.
,
Rahaman
,
M. N.
,
Dogan
,
F.
, and
Bal
,
B. S.
,
2008
, “
Freeze Casting of Porous Hydroxyapatite Scaffolds—Part I: Processing and General Microstructure
,”
J. Biomed. Mater. Res. Part B
,
86
(
1
), pp.
125
135
.
8.
Deville
,
S.
,
Saiz
,
E.
,
Nalla
,
R. K.
, and
Tomsia
,
A. P.
,
2006
, “
Freezing as a Path to Build Complex Composites
,”
Science
,
311
(
5760
), pp.
515
518
.
9.
Munch
,
E.
,
Launey
,
M. E.
,
Alsem
,
D. H.
,
Saiz
,
E.
,
Tomsia
,
A. P.
, and
Ritchie
,
R. O.
,
2008
, “
Tough, Bio-Inspired Hybrid Materials
,”
Science
,
322
(
5907
), pp.
1516
1520
.
10.
Lee
,
E.-J.
,
Koh
,
Y.-H.
,
Yoon
,
B.-H.
,
Kim
,
H.-E.
, and
Kim
,
H.-W.
,
2007
, “
Highly Porous Hydroxyapatite Bioceramics With Interconnected Pore Channels Using Camphene-Based Freeze Casting
,”
Mater. Lett.
,
61
(
11–12
), pp.
2270
2273
.
11.
Macchetta
,
A.
,
Turner
,
I. G.
, and
Bowen
,
C. R.
,
2009
, “
Fabrication of HA/TCP Scaffolds With a Graded and Porous Structure Using a Camphene-Based Freeze-Casting Method
,”
Acta Biomater.
,
5
(
4
), pp.
1319
1327
.
12.
Fu
,
Q.
,
Rahaman
,
M. N.
,
Dogan
,
F.
, and
Bal
,
B. S.
,
2008
, “
Freeze Casting of Porous Hydroxyapatite Scaffolds—Part II: Sintering, Microstructure, and Mechanical Behavior
,”
J. Biomed. Mater. Res. Part B
,
86
(
2
), pp.
514
522
.
13.
Yoon
,
B.-H.
,
Koh
,
Y.-H.
,
Park
,
C.-S.
, and
Kim
,
H.-E.
,
2007
, “
Generation of Large Pore Channels for Bone Tissue Engineering Using Camphene-Based Freeze Casting
,”
J. Am. Ceram. Soc.
,
90
(
6
), pp.
1744
1752
.
14.
Yoon
,
B.-H.
,
Park
,
C.-S.
,
Kim
,
H.-E.
, and
Koh
,
Y.-H.
,
2008
, “
In-Situ Fabrication of Porous Hydroxyapatite (HA) Scaffolds With Dense Shells by Freezing HA/Camphene Slurry
,”
Mater. Lett.
,
62
(
10–11
), pp.
1700
1703
.
15.
Yang
,
T. Y.
,
Lee
,
J. M.
,
Yoon
,
S. Y.
, and
Park
,
H. C.
,
2010
, “
Hydroxyapatite Scaffolds Processed Using a TBA-Based Freeze-Gel Casting/Polymer Sponge Technique
,”
J. Mater. Sci.: Mater. Med.
,
21
(
5
), pp.
1495
1502
.
16.
Kim
,
J. H.
,
Lee
,
J. H.
,
Yang
,
T. Y.
,
Yoon
,
S. Y.
,
Kim
,
B. K.
, and
Park
,
H. C.
,
2011
, “
TBA-Based Freeze/Gel Casting of Porous Hydroxyapatite Scaffolds
,”
Ceram. Int.
,
37
(
7
), pp.
2317
2322
.
17.
Kim
,
T. W.
,
Ryu
,
S. C.
,
Kim
,
B. K.
,
Yoon
,
S. Y.
, and
Park
,
H. C.
,
2014
, “
Porous Hydroxyapatite Scaffolds Containing Calcium Phosphate Glass-Ceramics Processed Using a Freeze/Gel-Casting Technique
,”
Met. Mater. Int.
,
20
(
1
), pp.
135
140
.
18.
Araki
,
K.
, and
Halloran
,
J. W.
,
2005
, “
Porous Ceramic Bodies With Interconnected Pore Channels by a Novel Freeze Casting Technique
,”
J. Am. Ceram. Soc.
,
88
(
5
), pp.
1108
1114
.
19.
Shuai
,
C.
,
Li
,
P.
,
Liu
,
J.
, and
Peng
,
S.
,
2013
, “
Optimization of TCP/HAP Ratio for Better Properties of Calcium Phosphate Scaffold Via Selective Laser Sintering
,”
Mater. Charact.
,
77
, pp.
23
31
.
20.
Feng
,
P.
,
Niu
,
M.
,
Gao
,
C.
,
Peng
,
S.
, and
Shuai
,
C.
,
2014
, “
A Novel Two-Step Sintering for Nano-Hydroxyapatite Scaffolds for Bone Tissue Engineering
,”
Sci. Rep.
,
4
, p.
5599
.
21.
Duan
,
S.
,
Feng
,
P.
,
Gao
,
C.
,
Xiao
,
T.
,
Yu
,
K.
,
Shuai
,
C.
, and
Peng
,
S.
,
2015
, “
Microstructure Evolution and Mechanical Properties Improvement in Liquid-Phase-Sintered Hydroxyapatite by Laser Sintering
,”
Materials
,
8
(
3
), pp. 1162–1175.
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