scholarly journals Photothermally Triggered Endosomal Escape and Its Influence on Transfection Efficiency of Gold-Functionalized JetPEI/pDNA Nanoparticles

2018 ◽  
Vol 19 (8) ◽  
pp. 2400 ◽  
Author(s):  
Lotte Vermeulen ◽  
Juan Fraire ◽  
Laurens Raes ◽  
Ellen De Meester ◽  
Sarah De Keulenaer ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Laser Irradiation ◽  
Laser Energy ◽  
Transfection Efficiency ◽  
Laser Pulses ◽  
High Energy ◽  
Endosomal Escape ◽  
Localized Surface Plasmon ◽  
Endosomal Membrane ◽  
Photothermal Effects

Plasmonic nanoparticles for drug delivery have attracted increasing interest over the last few years. Their localized surface plasmon resonance causes photothermal effects on laser irradiation, which allows for delivering drugs in a spatio-temporally controlled manner. Here, we explore the use of gold nanoparticles (AuNP) as carriers for pDNA in combination with pulsed laser irradiation to induce endosomal escape, which is currently considered to be one of the major bottlenecks in macromolecular drug delivery on the intracellular level. In particular, we evaluate nanocomplexes composed of JetPEI (polyethylenimine)pDNA and 10 nm AuNP, which do not exhibit endosomal escape by themselves. After incubating HeLa cells with these complexes, we evaluated endosomal escape and transfection efficiency using low- and high-energy laser pulses. At low laser energy heat is produced by the nanocomplexes, while, at higher laser energy, explosive vapour nanobubbles (VNB) are formed. We investigated the ability of heat transfer and VNB formation to induce endosomal escape and we examine the integrity of pDNA cargo after inducing both photothermal effects. We conclude that JetPEI/pDNA/AuNP complexes are unable to induce meaningful transfection efficiencies because laser treatment causes either dysfunctionality of the cargo when VNB are formed or forms too small pores in the endosomal membrane to allow pDNA to escape in case of heating. We conclude that laser-induced VNB is the most suitable to induce effective pDNA endosomal escape, but a different nanocomplex structure will be required to keep the pDNA intact.

Time-Resolved X-Ray Studies During Pulsed-Laser Irradiation of Ge

1984 ◽  
Vol 35 ◽  
Author(s):  
J.Z. Tischler ◽  
B.C. Larson ◽  
D.M. Mills
Keyword(s):  
Melting Point ◽  
Laser Irradiation ◽  
Pulsed Laser ◽  
Laser Pulses ◽  
High Energy ◽  
Measured Temperature ◽  
Time Resolved ◽  
Synchrotron Source ◽  
X Ray ◽  
Pulsed Laser Irradiation

ABSTRACTSynchrotron x-ray pulses from the Cornell High Energy Synchrotron Source (CHESS) have been used to carry out nanosecond resolution measurements of the temperature distrubutions in Ge during UV pulsed-laser irradiation. KrF (249 nm) laser pulses of 25 ns FWHM with an energy density of 0.6 J/cm2 were used. The temperatures were determined from x-ray Bragg profile measurements of thermal expansion induced strain on <111> oriented Ge. The data indicate the presence of a liquid-solid interface near the melting point, and large (1500-4500°C/pm) temperature gradients in the solid; these Ge results are analagous to previous ones for Si. The measured temperature distributions are compared with those obtained from heat flow calculations, and the overheating and undercooling of the interface relative to the equilibrium melting point are discussed.

Laser Irradiation Effect on Saw Properties of Layered Structure of Oxide/Piezoelectric Substrate

1996 ◽  
Vol 459 ◽  
Author(s):  
Yo Ichikawa ◽  
Masatoshi Kitagawa ◽  
Kentaro Setsune ◽  
Syun-ichiro Kawashima
Keyword(s):  
Laser Irradiation ◽  
Layered Structure ◽  
Laser Energy ◽  
Laser Pulses ◽  
Elastic Stiffness ◽  
Center Frequency ◽  
Irradiation Effect ◽  
Saw Devices ◽  
Krf Excimer Laser ◽  
Piezoelectric Substrate

ABSTRACTUsing surface acoustic wave (SAW) propagating in the layered structure of oxide/piezoelectric substrate, a responsibility of the oxide thin films for the laser irradiation has been investigated. Amorphous Ti-O, Si-O and Si-X-O, where X is other metal elements, films were formed on the surface of the SAW device composed of quartz or LiTaO3 substrate and several hundred Al electrode fingers for oscillating and detecting the SAW. A KrF excimer laser with 248nm in wavelength was used for the irradiation. The center frequency of the SAW devices was immediately decreased by the irradiation of the laser pulses. Although the response to the irradiation was reversible for lower laser energy, the change of the center frequency was irreversible for the laser energy density higher than 20mJ/cm2. It is considered that the response appeared in the frequency shift is generated by a change of an elastic stiffness of the films lowered by an absorption of the laser energy.

Effect of Multiple Pulses on the Deformation Behavior of Ultrathin Metal Foils in 3D Micro-Scale Laser Dynamic Forming

2010 ◽  
Author(s):  
Ji Li ◽  
Gary J. Cheng
Keyword(s):  
Deformation Behavior ◽  
Laser Energy ◽  
3D Structure ◽  
Single Pulse ◽  
Laser Pulses ◽  
High Energy ◽  
Shock Pressure ◽  
Thickness Variation ◽  
Multiple Pulse ◽  
Multiple Pulses

Laser dynamic forming (LDF) is a novel high energy rate microfabrication technique, which makes use of the shock pressure induced by laser to generate dynamic high strain rate 3D forming of thin films. In LDF process, a high shock pressure accelerates the workpiece to a high velocity and deforms it into complex 3D shapes. The forming velocity of the workpiece imparted by a single laser pulse with high energy may exceed the critical forming velocity of the material, and thus causing it to fracture. This problem is more severe when 3D structure of large aspect ratio needs to be formed. To overcome this problem, multi-pulse laser dynamic forming is investigated in this study. The total laser energy is evenly distributed in different laser pulses to keep the forming velocity below the critical forming velocity of the material. The effects of the multiple-pulse LDF on the deformation behavior of ultra thin foils are investigated. The deformation depth and thickness variation distribution of the formed 3D features are characterized to reveal these effects. In addition, the effects of vacuum conditions on multiple-pulse LDF process are carried out. It is found that the bounce off of the foil can be effectively reduced by multiple-pulse LDF and the final shape could be controlled much more accurately. By extending single pulse LDF to multi-pulse LDF, the forming capability of LDF is further enhanced, and thus enlarges the applicable range of this technique.

scholarly journals Interaction of annular-focused laser beams with solid targets

2015 ◽  
Vol 33 (3) ◽  
pp. 541-550 ◽  
Author(s):  
N.E. Andreev ◽  
M.E. Povarnitsyn ◽  
M.E. Veysman ◽  
A.YA. Faenov ◽  
P.R. Levashov ◽  
...  
Keyword(s):  
Laser Energy ◽  
Laser Pulses ◽  
Heavy Ion ◽  
High Energy ◽  
Weakly Coupled ◽  
Wide Range ◽  
Energy Laser ◽  
High Energy Laser ◽  
Hydrodynamic Code ◽  
Two Temperature

AbstractThe two-temperature, 2D hydrodynamic code Hydro–ELectro–IOnization–2–Dimensional (HELIO2D), which takes into account self-consistently the laser energy absorption in a target, ionization, heating, and expansion of the created plasma is elaborated. The wide-range two-temperature equation of state is developed and used to model the metal target dynamics from room temperature to the conditions of weakly coupled plasma. The simulation results are compared and demonstrated a good agreement with experimental data on the Mg target being heated by laser pulses of the nanosecond high-energy laser for heavy ion experiments (NHELIX) at Gesellschaft fur Schwerionenforschung. The importance of using realistic models of matter properties is demonstrated.

scholarly journals Ultra-intense laser pulses in near-critical underdense plasmas – radiation reaction and energy partitioning

2017 ◽  
Vol 83 (2) ◽  
Author(s):  
Erik Wallin ◽  
Arkady Gonoskov ◽  
Christopher Harvey ◽  
Olle Lundh ◽  
Mattias Marklund
Keyword(s):  
Laser Pulse ◽  
Pulse Propagation ◽  
Laser Energy ◽  
Radiation Reaction ◽  
Laser Pulses ◽  
High Energy ◽  
Intense Laser ◽  
Long Distance ◽  
Weakly Nonlinear ◽  
Highly Nonlinear

Although, for current laser pulse energies, the weakly nonlinear regime of laser wakefield acceleration is known to be the optimal for reaching the highest possible electron energies, the capabilities of upcoming large laser systems will provide the possibility of running highly nonlinear regimes of laser pulse propagation in underdense or near-critical plasmas. Using an extended particle-in-cell (PIC) model that takes into account all the relevant physics, we show that such regimes can be implemented with external guiding for a relatively long distance of propagation and allow for the stable transformation of laser energy into other types of energy, including the kinetic energy of a large number of high energy electrons and their incoherent emission of photons. This is despite the fact that the high intensity of the laser pulse triggers a number of new mechanisms of energy depletion, which we investigate systematically.

scholarly journals Theoretical investigation of high-energy ions produced from laser-cluster interactions

2003 ◽  
Vol 21 (4) ◽  
pp. 593-597 ◽  
Author(s):  
PINPIN ZHU ◽  
JIANSHENG LIU ◽  
ZHIZHAN XU
Keyword(s):  
Kinetic Energy ◽  
Laser Energy ◽  
Coupling Efficiency ◽  
Laser Pulses ◽  
High Energy ◽  
Femtosecond Laser Pulses ◽  
Effective Dielectric Constant ◽  
Absorption Mechanism ◽  
High Energy Ions ◽  
Mean Kinetic Energy

By using an effective dielectric constant to modify the nanoplasma model, the interactions of large Ar clusters with high-intensity femtosecond laser pulses have been studied. It is shown that the resonance absorption mechanism plays a predominant role in the production of highly energetic argon ions, and the calculated mean kinetic energy of Ar ions is in good agreement with our previous experimental results. The scaling of mean kinetic energy and charge states of Ar ions against cluster size and laser intensity has also been analyzed. The results indicate the existence of optimum cluster sizes and optimum laser intensities where the best coupling efficiency of the laser energy can be obtained.

scholarly journals Chemo-photothermal effects of doxorubicin/silica–carbon hollow spheres on liver cancer

RSC Advances ◽  
2018 ◽  
Vol 8 (64) ◽  
pp. 36775-36784 ◽  
Author(s):  
Ying-Chi Chen ◽  
Wen-Tai Chiu ◽  
Chin Chang ◽  
Ping-Ching Wu ◽  
Ting-Yuan Tu ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Liver Cancer ◽  
Cancer Cells ◽  
Laser Irradiation ◽  
Hollow Spheres ◽  
Liver Cancer Cells ◽  
Photothermal Effects ◽  
Carbon Hollow Spheres ◽  
Nir Laser

SCHSs were applied as vectors for drug delivery and thermal production under NIR laser irradiation. DOX-loaded SCHSs conjugated with ConA were found to kill liver cancer cells efficiently.

Raman Measurements on Graphite Modified by High Power Laser Irradiation

1984 ◽  
Vol 35 ◽  
Author(s):  
J. Steinbeck ◽  
G. Braunstein ◽  
M.S. Dresselhaus ◽  
B.S. Elman ◽  
T. Venkatesan
Keyword(s):  
Energy Density ◽  
Laser Pulse ◽  
Laser Irradiation ◽  
High Power ◽  
Laser Energy ◽  
Laser Pulses ◽  
Laser Energy Density ◽  
High Power Laser ◽  
Power Laser ◽  
Raman Microprobe

AbstractThe behavior of highly anisotropic materials under short pulses of high power laser irradiation has been studied by irradiating highly oriented pyrolytic graphite (HOPG) with 30 nsec Ruby-laser pulses with energy densities between 0.1 and 5.0J/cm2. Raman spectroscopy has been used to investigate the laser-induced modifications to the crystalline structure as a function of laser energy density of the laser pulse. A Raman microprobe was used to investigate the spatial variations of these near-surface regions. The irradiation of HOPG with energy densities above ~ 0.6J/cm2 leads to the appearance of the ~ 1360 cm-1 disorder-induced line in the first order Raman spectrum. The intensity of the ~ 1360cm-1 line increases with increasing laser energy density. As the energy density of the laser pulse reaches about 1.0J/cm2, the ~ 1360cm-1 line and the ~ 1580cm-1 Raman-allowed mode broaden and coalesce into a broad asymmetric band, indicating the formation of a highly disordered region, consistent with RBS-channeling measurements. However, as the laser energy density of the laser pulses is further increased above 3.0J/cm2, the two Raman lines narrow and can again be resolved suggesting laser-induced crystallization. The Raman results are consistent with high resolution electron microscopy observations showing the formation of randomly oriented crystallites. Raman Microprobe spectra revealed three separate regions of behavior: (i) an outer unirradiated region where the material appears HOPG-like with a thin layer of material coating the surface, (ii) an inner irradiated region where the structure is uniform, but disordered, and (iii) an intermediate region between the other regions where the structure is highly disordered. The changes in structure of the inner region are consistent with the behavior observed with RBS and conventional Raman spectra. The identification of an amorphous carbon-like layer on the outer region is consistent with a large thermomechanical stress at the graphite surface, introduced by the high power laser pulse, and known to occur in metals.

scholarly journals Femtosecond laser-induced damage threshold in snow micro-structured targets

2018 ◽  
Vol 6 ◽  
Author(s):  
O. Shavit ◽  
Y. Ferber ◽  
J. Papeer ◽  
E. Schleifer ◽  
M. Botton ◽  
...  
Keyword(s):  
Laser Energy ◽  
Local Density ◽  
Damage Threshold ◽  
Laser Pulses ◽  
High Energy ◽  
Hot Electron ◽  
Short Laser Pulses ◽  
Laser Induced Damage ◽  
Pulse Structure ◽  
Positively Charged

Enhanced acceleration of protons to high energy by relatively modest high power ultra-short laser pulses, interacting with snow micro-structured targets was recently proposed. A notably increased proton energy was attributed to a combination of several mechanisms such as localized enhancement of the laser field intensity near the tip of $1~\unicode[STIX]{x03BC}\text{m}$ size whisker and increase in the hot electron concentration near the tip. Moreover, the use of mass-limited target prevents undesirable spread of absorbed laser energy out of the interaction zone. With increasing laser intensity a Coulomb explosion of the positively charged whisker will occur. All these mechanisms are functions of the local density profile and strongly depend on the laser pre-pulse structure. To clarify the effect of the pre-pulse on the state of the snow micro-structured target at the time of interaction with the main pulse, we measured the optical damage threshold (ODT) of the snow targets. ODT of $0.4~\text{J}/\text{cm}^{2}$ was measured by irradiating snow micro-structured targets with 50 fs duration pulses of Ti:Sapphire laser.

scholarly journals Effect of laser pulse time profile on its absorption by argon clusters

2011 ◽  
Vol 29 (3) ◽  
pp. 305-313 ◽  
Author(s):  
Gaurav Mishra ◽  
Amol R. Holkundkar ◽  
N.K. Gupta
Keyword(s):  
Laser Pulse ◽  
Pulse Duration ◽  
Laser Energy ◽  
Three Dimensional ◽  
Laser Pulses ◽  
High Energy ◽  
Femtosecond Laser Pulses ◽  
Time Profile ◽  
Argon Clusters ◽  
Cluster Distance

AbstractThe interaction of medium sized Argon clusters (30 Å) with high-intensity femtosecond laser pulses (806 nm, 8 × 1016 W/cm2) of durations ranging from 10 fs to 120 fs have been studied using a three-dimensional relativistic time dependent molecular dynamic approach. The dynamics of cluster expansion is explained in terms of temporal evolution of electron population in the cluster and snapshots of particle positions at various times. The effects of inter-cluster distance on ionization dynamics are presented. It is observed that the collisional ionization increases with decreasing inter-cluster distance. The effect of pulse duration on laser energy absorption is also studied. For a laser pulse of gaussian time profile, there exists an optimum pulse duration for maximum absorption. No such optimum exists for a nearly flat top (super-gaussian) laser pulse. Results indicate the existence of resonance absorption inside the cluster. It is also observed that the high energy component of ion emission from cluster is anisotropic, showing a preferential direction of emission along laser polarization while the low energy ions emerge almost isotropically.

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