440
S. Arthanari et al.
biomolecules and fluorescence enhancement on the hierarchical LIPSS surfaces for
clinical applications are also discussed.
Keywords Laser processing · Micro/nano surface · Metals · Implants ·
Biomaterials
1 Introduction to Metallic Implants and Surface
Treatments
Surface treatments of metallic materials are important to enhance the surface-related
properties without altering the bulk properties of the materials. In particular, the
surface properties of materials used in biomedical applications need to be tailored
to respond to the surrounding environments [1]. Several metallic materials including
steels, Co-Cr, Titanium, Magnesium, Zinc and Fe based alloys are considered for
the implant applications and metallic implants are about 70-80% of the available
implant materials [2]. Among them, steels, Co-Cr, and Ti alloys are commercially
used and their properties are well established [3]. Mg and Zn based alloys are not well
established in the markets and continuous research is undergoing to develop them
as biodegradable implant materials. The metallic materials exhibit different physical
and chemical properties when they are exposed to physiological solutions. Steels and
Ti alloys are permanent implant materials, while Mg-based alloys are degradable
during service. The surface layer formed on the permanent implant materials is
relatively stable and controls the diffusion of aggressive ions (such as Cl
− , SO 4
2− ,
-CO 3
2− , etc.,) present in the physiological solution, thereby controlling the chemical
degradation and establishing a stable surface. Nevertheless, these materials have
limited interaction with the living cells and bone healing properties since they have
higher Young’s modulus compared to the natural bone which produces a stressshielding effect. In addition to that, the surface nature such as porosity plays a key
role in determining the ability to bond with the natural tissues during service.
Interestingly, Mg-based alloys have similar mechanical properties to that of the
natural bone, thus they minimize the stress-shielding effect. However, Mg alloys
suffer severe corrosion and hydrogen gas evolution in the physiological solution
thus limiting the bone-bonding ability during service. Degradable Fe based implant
materials are also given attention due to their exceptional mechanical properties,
excellent formability, and better biocompatibility. The very low degradation rates of
the Fe based alloys lead to long-term retention in the body and limits their widespread
applications. Zn based alloys are focused as potential implant material in recent
research due to their outstanding properties such as biodegradability and biocompatibility and they overcome the challenges of Mg and Fe based implant materials.
However, Zn alloys have weak mechanical properties compared to Mg and Fe based
alloys, and researchers are consistently working on improving the mechanical properties through various techniques. Addition of alloying elements to Zn during alloy
S. Arthanari et al.
biomolecules and fluorescence enhancement on the hierarchical LIPSS surfaces for
clinical applications are also discussed.
Keywords Laser processing · Micro/nano surface · Metals · Implants ·
Biomaterials
1 Introduction to Metallic Implants and Surface
Treatments
Surface treatments of metallic materials are important to enhance the surface-related
properties without altering the bulk properties of the materials. In particular, the
surface properties of materials used in biomedical applications need to be tailored
to respond to the surrounding environments [1]. Several metallic materials including
steels, Co-Cr, Titanium, Magnesium, Zinc and Fe based alloys are considered for
the implant applications and metallic implants are about 70-80% of the available
implant materials [2]. Among them, steels, Co-Cr, and Ti alloys are commercially
used and their properties are well established [3]. Mg and Zn based alloys are not well
established in the markets and continuous research is undergoing to develop them
as biodegradable implant materials. The metallic materials exhibit different physical
and chemical properties when they are exposed to physiological solutions. Steels and
Ti alloys are permanent implant materials, while Mg-based alloys are degradable
during service. The surface layer formed on the permanent implant materials is
relatively stable and controls the diffusion of aggressive ions (such as Cl
− , SO 4
2− ,
-CO 3
2− , etc.,) present in the physiological solution, thereby controlling the chemical
degradation and establishing a stable surface. Nevertheless, these materials have
limited interaction with the living cells and bone healing properties since they have
higher Young’s modulus compared to the natural bone which produces a stressshielding effect. In addition to that, the surface nature such as porosity plays a key
role in determining the ability to bond with the natural tissues during service.
Interestingly, Mg-based alloys have similar mechanical properties to that of the
natural bone, thus they minimize the stress-shielding effect. However, Mg alloys
suffer severe corrosion and hydrogen gas evolution in the physiological solution
thus limiting the bone-bonding ability during service. Degradable Fe based implant
materials are also given attention due to their exceptional mechanical properties,
excellent formability, and better biocompatibility. The very low degradation rates of
the Fe based alloys lead to long-term retention in the body and limits their widespread
applications. Zn based alloys are focused as potential implant material in recent
research due to their outstanding properties such as biodegradability and biocompatibility and they overcome the challenges of Mg and Fe based implant materials.
However, Zn alloys have weak mechanical properties compared to Mg and Fe based
alloys, and researchers are consistently working on improving the mechanical properties through various techniques. Addition of alloying elements to Zn during alloy