Nucleus remains a significant target for nanoparticles with diagnostic and therapeutic applications because both genetic
information of the cell and transcription machinery reside there. Novel therapeutic strategies (for example, gene
therapy), enabled by safe and efficient delivery of nanoparticles and drug molecules into the nucleus, are heralded by
many as the ultimate treatment for severe and intractable diseases. However, most nanomaterials and macromolecules
are incapable of reaching the cell nucleus on their own, because of biological barriers carefully honed by evolution
including cellular membrane and nuclear envelope. In this paper, we have demonstrated an approach of fabrication of
biocompatible gold nanoparticle (Au NP)-based vehicles which can entering into cancer cell nucleus by modifying Au
NPs with both PEG 5000 and two different peptides (RGD and nuclear localization signal (NLS) peptide). The Au NPs
used were fabricated via femtosecond laser ablation of Au bulk target in deionized water. The Au NPs produced by this
method provide chemical free, virgin surface, which allows us to carry out “Sequential Conjugation” to modify their
surface with PEG 5000, RGD, and NLS. “Sequential Conjugation” described in this presentation is very critical for the
fabrication of Au NP-based vehicles capable of entering into cancer cell nucleus as it enables the engineering and tuning
surface chemistries of Au NPs by independently adjusting amounts of PEG and peptides bound onto surface of Au NPs
so as to maximize their nuclear targeting performance and biocompatibility regarding the cell line of interest. Both
optical microscopy and transmission electron microscopy (TEM) are used to confirm the in vitro targeted nuclear
delivery of peptide-conjugated biocompatible Au NPs by showing their presence in the cancer cell nucleus.
This paper demonstrates a new method for fabrication of stable gold nanoparticle-poly(ethylene glycol) (PEG)
conjugates with a defined number of PEG molecules. The PEG molecules are directly bound to the surface of gold
nanoparticles with almost 100% conjugation efficiency and the PEG surface coverage is tunable between values of 0
and 100%. Gold nanoparticles for the nanoparticle PEG conjugates are prepared by femtosecond laser ablation in liquid
of a gold bulk target in deionized water. This method for fabrication of nanoparticles creates gold surfaces which are
negatively charged and chemically clean. This facilitates uniform and controlled binding of thiolated PEG molecules to the surface of the gold nanoparticles. The method used to bind PEG to gold can be used with other biomolecules to prepare gold nanoparticles with single or mixed monolayers of biologically important molecules.
Ultrafast pulsed laser ablation is employed in laser-induced backward transfer for printing on transparent media. By
combining a high pulse repetition rate of 1 MHz and an ultrashort pulse duration of 700 fs in an ultrafast fiber laser, we
demonstrate printing of bitmap images and vector graphics with nearly continuous gray scales and high linear printing
speeds up to 10 m/s. In addition, we find that the printing process preserves several original functional properties of the
target material, and as an example of functional printing, we demonstrate printing of phosphorescent images.
We address recent fiber-based femtosecond laser technology. Specifically, fiber-chirped pulse amplifier is discussed for
the enabling the concept of real-world applications. We review recent selected material applications demonstrating advantages of ultrafast dynamics of highly repetitive pulse train in nanoparticle generation in pulsed-laser deposition and reliable Si wafer singulation.
We have performed a systematic study of nanoparticle generation using near infrared ultrafast pulsed laser ablation.
The materials we have studied include metal, metal alloy, and metal oxide. We find that by optimizing the ablation
conditions, as a direct result of ultrafast pulsed laser ablation, polycrystalline and single-crystalline nanoparticles can be
abundantly produced without intermediate nucleation and growth processes. Combining with different background
gases, versatile structural forms have been obtained for the nanocrystals. Using metal nickel as a sample material, we
have produced Ni/NiO core/shell nano-spheres and NiO nano-cubes. In the study of generation of alloy nanoparticles,
which has been challenging in fabrication, we demonstrate production of binary alloy NiFe nanoparticles that have the
same composition as the target material. Metal alloy nanoparticles containing up to three elements are also produced.
For metal oxide nanoparticles, two important oxide materials are studied, including TiO2 and ZnO. All nanoparticle
samples are examined using high resolution transmission electron microscopy for morphological, structural, and
chemical analysis. An ion probe is used in situ to study the laser ablation process in real-time.
Near infrared ultrafast pulsed laser is used to ablate pure metal and metal alloy targets in a vacuum chamber. We find that by optimizing the ablation conditions, as a direct result of ultrafast laser ablation, crystalline nanoparticles can be abundantly produced without intermediate nucleation and growth processes. Combining with different background gases, versatile structural forms can also be obtained for the nanocrystals. Using metal nickel as a sample material, we have produced Ni/NiO core/shell nanospheres and NiO nanocubes. We also study the production of alloy nanoparticles, which has been challenging in fabrication. We demonstrate production of nanoparticles containing up to three metal elements using ultrafast laser ablation. The laser ablation process is investigated using an ion probe in real-time. Nanoparticle samples are examined using atomic force microscopy and high resolution transmission electron microscopy for morphological, structural, and chemical analysis. This study provides a simple physical method for generating nanoparticles with a narrow particle size distribution, a high particle yield, versatile chemical compositions and structural forms.