Laser Induced Micro/Nano …
457
of 60-200 nm were randomly observed in the ripples [72]. A thin Au coating was
further deposited on the produced LIPSS structures by an electron beam evaporation
technique as the Au enhances the Raman signal. Crystal violet probe molecule was
dropped on different surfaces (polished, LIPSS and Au coated LIPSS), subjected to
Raman analysis and it revealed that the enhancement of the Raman signal was in
the factor of 10
3 and 6.7 × 10
3 for the LIPSS and Au coated LIPSS, respectively
(Fig. 6A).
The localized surface plasma resonance (LSPR) was mainly responsible to confine
the electromagnetic field when the dimension of the nanoparticles was less than the
incident wavelength. The nanoparticles produced on the LIPSS were in the range of
60-200 nm and were mainly responsible for the enhanced Raman signal compared
to surface plasma polaritons (SPP) on the LIPSS. These results indicated that laserinduced surface texturing is a reliable tool for the enhancement of the Raman signals
of biomolecules, thus increasing the application in detecting the biomolecule which
is very important for the biomedical field.
Another important application of the LIPSS surface is the enhancement of fluorescence detection and fluorescence imaging is a widely used tool in biomedical
fields. Nanomaterials play a key role to measure and enhance fluorescence imaging.
The fluorescence detection efficiencies are significantly altered by the size of the subwavelength nanoparticles. It is known that the highly ordered nanomaterials prepared
using conventional methods would require sophisticated instrumentation facilities,
and in fact, sometimes the reproducibility and application rage become questionable. Therefore, there is a huge demand for a feasible and reproducible technology
to produce the periodic surface structure (PSS), which confines the local electromagnetic (EM) filed on the structured surface and enhances the fluorescence detection. In
an attempt, Jiaru et al. have recently fabricated a LIPSS on TC4 Titanium alloy which
is commonly used in implant applications and the fabricated surfaces had enhancement factor of about 74 with bovine serum albumin (BSA) and the minimum Cu
detection limit was 1.5 μg/ml (Fig. 6B) [15]. The enhancement in the fluorescence
intensity was mainly attributed to the two forms of surface plasmon resonance (SPR)
effect such as SPP and LSPR. The size of the nanoparticles plays a huge role in
determining the LSPR and SPP effects, and the nanoparticle size smaller than the
wavelength of incident light showed stronger dipolar excitation in the form of LSPR.
Furthermore, the enhancement factor for the hierarchical LIPSS was about 6 times
higher than the LIPSS which was attributed to the large surface area with more
nanoparticles which could allow more interaction and result in stronger LSPR.
4 Future Prospects of Laser Processing for Biomedical
Applications
The recent literature studies show that continuous research works are focused on
using the laser as non-contact and high precision technology to modify the surface
457
of 60-200 nm were randomly observed in the ripples [72]. A thin Au coating was
further deposited on the produced LIPSS structures by an electron beam evaporation
technique as the Au enhances the Raman signal. Crystal violet probe molecule was
dropped on different surfaces (polished, LIPSS and Au coated LIPSS), subjected to
Raman analysis and it revealed that the enhancement of the Raman signal was in
the factor of 10
3 and 6.7 × 10
3 for the LIPSS and Au coated LIPSS, respectively
(Fig. 6A).
The localized surface plasma resonance (LSPR) was mainly responsible to confine
the electromagnetic field when the dimension of the nanoparticles was less than the
incident wavelength. The nanoparticles produced on the LIPSS were in the range of
60-200 nm and were mainly responsible for the enhanced Raman signal compared
to surface plasma polaritons (SPP) on the LIPSS. These results indicated that laserinduced surface texturing is a reliable tool for the enhancement of the Raman signals
of biomolecules, thus increasing the application in detecting the biomolecule which
is very important for the biomedical field.
Another important application of the LIPSS surface is the enhancement of fluorescence detection and fluorescence imaging is a widely used tool in biomedical
fields. Nanomaterials play a key role to measure and enhance fluorescence imaging.
The fluorescence detection efficiencies are significantly altered by the size of the subwavelength nanoparticles. It is known that the highly ordered nanomaterials prepared
using conventional methods would require sophisticated instrumentation facilities,
and in fact, sometimes the reproducibility and application rage become questionable. Therefore, there is a huge demand for a feasible and reproducible technology
to produce the periodic surface structure (PSS), which confines the local electromagnetic (EM) filed on the structured surface and enhances the fluorescence detection. In
an attempt, Jiaru et al. have recently fabricated a LIPSS on TC4 Titanium alloy which
is commonly used in implant applications and the fabricated surfaces had enhancement factor of about 74 with bovine serum albumin (BSA) and the minimum Cu
detection limit was 1.5 μg/ml (Fig. 6B) [15]. The enhancement in the fluorescence
intensity was mainly attributed to the two forms of surface plasmon resonance (SPR)
effect such as SPP and LSPR. The size of the nanoparticles plays a huge role in
determining the LSPR and SPP effects, and the nanoparticle size smaller than the
wavelength of incident light showed stronger dipolar excitation in the form of LSPR.
Furthermore, the enhancement factor for the hierarchical LIPSS was about 6 times
higher than the LIPSS which was attributed to the large surface area with more
nanoparticles which could allow more interaction and result in stronger LSPR.
4 Future Prospects of Laser Processing for Biomedical
Applications
The recent literature studies show that continuous research works are focused on
using the laser as non-contact and high precision technology to modify the surface