Ultrafast Pulsed Laser Induced Nanocrystal Transformation in Colloidal Plasmonic Vesicles (original) (raw)
Related papers
Vesicle Fusion Triggered by Optically Heated Gold Nanoparticles
Membrane fusion can be accelerated by heating that causes membrane melting and expansion. We locally heated the membranes of two adjacent vesicles by laser irradiating gold nanoparticles, thus causing vesicle fusion with associated membrane and cargo mixing. The mixing time scales were consistent with diffusive mixing of the membrane dyes and the aqueous content. This method is useful for nanoscale reactions as demonstrated here by I-BAR protein-mediated membrane tubulation triggered by fusion. T he fusion of the cargos of two selected vesicles allows for controlled nanoscale reactions with femtoliter volumes, thus paving the way for single-or few-molecule reactions. This is highly useful for studying the dynamics of chemical reactions. 1 Fusion of vesicles, or fusion of vesicles with cells is the heart of liposome based targeted drug delivery, a topic of large medical interest. Fusion of one cell with another allows for the creation of hybrid cells that combines the properties of several cell types. Examples include (i) hybridoma technology, 2 which can be used to create monoclonal antibodies, (ii) combination of stem cells with differentiated cells with the potential for novel diabetes treatments through pancreatic islet transplantation, 3 or (iii) the fusion of dendritic cells to a triply negative breast cancer cell, which can be exploited for vaccine creation. 4 As fusion of vesicles and cells is of high interest, considerable effort has been put into developing efficient methods for fusion. There exists an extensive library of biological and chemical molecules that trigger fusion of cells and vesicles, for instance, cellular expressed fusogenic proteins, 5 PEG-polymers incorporated into the membranes, 6 lanthanide salts, 7 viral-based fusion peptides, 8 synaptic SNARE-mediated fusion complexes, 9 or synthetic molecular fusion complexes based on nucleotides. 10 However, fusion can also be mediated by physical means, for instance, via electrofusion 1,3,4,11 or by locally irradiating ultraviolet (UV) light on the contact area between two membranes. Cell-cell fusion can be accomplished by irradiating a cell population in medium with a high powered pulsed UV laser, 12,13 however, with limited control over the system. A more sophisticated implementation of the pulsed UV laser-mediated fusion was demonstrated for immune cells that were brought into contact via an antibody-conjugated nano-particle. 14 The use of intense UV-laser pulses causes generation of highly reactive free radicals, which is an undesirable side-effect when dealing with live cell samples. Although such lasers are focused to a diffraction limited spot, they exhibit high divergence and still illuminate a substantial part of the cells or GUVs (giant unilamellar vesicles) both below and above the focal spot. Here, we report on a novel and efficient method for triggering fusion of two vesicles with one critical benefit being that two vesicles can be specifically chosen among a population. The method is based on optical trapping of a metallic nanoparticle by near-infrared (NIR) light that is essentially harmless to biological material. The metallic nanoparticle will absorb part of the NIR light and the absorbed energy will be dissipated as heat in the surroundings on a length scale comparable to the diameter of the particle, 15,16 and it is this local temperature elevation that triggers membrane heating, expansion, and fusion, possibly by opening a fusion pore. Using the optical trap, two selected GUVs are manipulated and brought into close proximity. 17 After the two selected GUVs are brought into contact, the trapping of a gold nanoparticle (AuNP) in the contact zone between the GUVs causes the two vesicles to fuse by a thermally triggered mechanism. This fusion causes the membranes and the cargos of the two vesicles to mix. In contrast to fusion methods based on UV lasers, essentially no biological damage is done above nor below the focal volume. Importantly, the process can be followed real-time in a microscope. To demonstrate the general applicability of this method we also prove fusion of GUVs existing in gel and fluid phases, respectively. Finally, as a relevant biophysical application we show how protein-mediated membrane shaping
Chinese Physics B, 2016
We have studied processes of interaction of pulsed laser radiation with resonant groups of plasmonic nanoparticles (resonant domains) in large colloidal nanoparticle aggregates having different interparticle gaps and particle size distributions. These processes are responsible for the origin of nonlinear optical effects and photochromic reactions in multiparticle aggregates. To describe photo-induced transformations in resonant domains and alterations in their absorption spectra remaining after the pulse action, we introduce the factor of spectral photomodification. Based on calculation of changes in thermodynamic, mechanical, and optical characteristics of the domains, the histograms of the spectrum photomodification factor have been obtained for various interparticle gaps, an average particle size, and the degree of polydispersity. Variations in spectra have been analyzed depending on the intensity of laser radiation and various combinations of size characteristics of domains. The obtained results can be used to predict manifestation of photochromic effects in composite materials containing different plasmonic nanoparticle aggregates in pulsed laser fields.
Laser-Induced Shape Changes of Colloidal Gold Nanorods Using Femtosecond and Nanosecond Laser Pulses
The Journal of Physical Chemistry B, 2000
Gold nanorods have been found to change their shape after excitation with intense pulsed laser irradiation. The final irradiation products strongly depend on the energy of the laser pulse as well as on its width. We performed a series of measurements in which the excitation power was varied over the range of the output power of an amplified femtosecond laser system producing pulses of 100 fs duration and a nanosecond optical parametric oscillator (OPO) laser system having a pulse width of 7 ns. The shape transformations of the gold nanorods are followed by two techniques: (1) visible absorption spectroscopy by monitoring the changes in the plasmon absorption bands characteristic for gold nanoparticles; (2) transmission electron microscopy (TEM) in order to analyze the final shape and size distribution. While at high laser fluences (∼1 J cm -2 ) the gold nanoparticles fragment, a melting of the nanorods into spherical nanoparticles (nanodots) is observed when the laser energy is lowered. Upon decreasing the energy of the excitation pulse, only partial melting of the nanorods takes place. Shorter but wider nanorods are observed in the final distribution as well as a higher abundance of particles having odd shapes (bent, twisted, φ-shaped, etc.). The threshold for complete melting of the nanorods with femtosecond laser pulses is about 0.01 J cm -2 . Comparing the results obtained using the two different types of excitation sources (femtosecond vs nanosecond laser), it is found that the energy threshold for a complete melting of the nanorods into nanodots is about 2 orders of magnitude higher when using nanosecond laser pulses than with femtosecond laser pulses. This is explained in terms of the successful competitive cooling process of the nanorods when the nanosecond laser pulses are used. For nanosecond pulse excitation, the absorption of the nanorods decreases during the laser pulse because of the bleaching of the longitudinal plasmon band. In addition, the cooling of the lattice occurring on the 100 ps time scale can effectively compete with the rate of absorption in the case of the nanosecond pulse excitation but not for the femtosecond pulse excitation. When the excitation source is a femtosecond laser pulse, the involved processes (absorption of the photons by the electrons (100 fs), heat transfer between the hot electrons and the lattice (<10 ps), melting (30 ps), and heat loss to the surrounding solvent (>100 ps) are clearly separated in time.
Optical Materials Express, 2017
We have studied light induced processes in nanocolloids and composite materials containing ordered and disordered aggregates of plasmonic nanoparticles accompanied by their strong heating. A universal comprehensive physical model that combines mechanical, electrodynamical, and thermal interactions at nanoscale has been developed as a tool for investigations. This model was used to gain deep insight on phenomena that take place in nanoparticle aggregates under high-intensity pulsed laser radiation resulting in the suppression of nanoparticle resonant properties. Verification of the model was carried out with single colloidal Au and Ag nanoparticles and their aggregates.
Optical Materials Express, 2017
We have studied light induced processes in nanocolloids and composite materials containing ordered and disordered aggregates of plasmonic nanoparticles accompanied by their strong heating. A universal comprehensive physical model that combines mechanical, electrodynamical, and thermal interactions at nanoscale has been developed as a tool for investigations. This model was used to gain deep insight on phenomena that take place in nanoparticle aggregates under high-intensity pulsed laser radiation resulting in the suppression of nanoparticle resonant properties. Verification of the model was carried out with single colloidal Au and Ag nanoparticles and their aggregates.
Scientific Reports
an in-depth study of fs-PLN at ultra-low pulse fluences using 47 nm gold nanoparticles, conjugated to antibodies that target the epithelial growth factor receptor and excited off-resonance using 760 nm, 270 fs laser pulses at 80 MHz repetition rate. We find that fs-PLN can optoporate cellular membranes with pulse fluences as low as 1.3 mJ/cm 2 , up to two orders of magnitude lower than those used at lower repetition rates. Our results, corroborated by simulations of free-electron generation by particle photoemission and photoionization of the surrounding water, shed light on the off-resonance fs-PLN mechanism. We suggest that photo-chemical pathways likely drive cellular optoporation and cell damage at these off-resonance, low fluence, and high repetition rate fs-laser pulses, with clusters acting as local concentrators of ROS generation. We believe that the low fluence and highly localized ROS-mediated fs-PLN approach will enable targeted therapeutics and cancer treatment.
Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating
Applied Surface Science, 2011
Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.
Journal of Nanoparticle Research, 2021
Gold nanoparticles (AuNPs), synthesized by ns-pulsed laser ablation in liquid (ns-PLAL) in the absence of any capping agents, are potential model systems to study the interactions with biological structures unencumbered by interference from the presence of stabilizers and capping agents. However, several aspects of the physics behind these AuNPs solutions deserve a detailed investigation. The structure in solution of ns-PLAL-synthesized AuNPs was investigated in solution by means of small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). Furthermore, the (dried) NPs have been examined using TEM. The analysis of the SAXS curve shows the presence of a large number of small aggregates with a fractal structure stabilized by strong long-range repulsive interactions. Fitting of the SAXS curve to a suitable “fractal model” allows the estimation of the features of the fractal including the fractal dimension d = 1.9. The latter allows to estimate the fraction of light scatter...
Optics Express, 2015
The intention of this paper is to study the physical mechanism underlying the response of gold nanoparticle (AuNP) dimers to a nearinfrared off-resonance femtosecond pulse laser in aqueous medium. We show that the strongly localized field enhancement in the gap distance and around nanoparticles significantly reduces the laser fluence threshold to achieve an optical breakdown in comparison with an AuNP monomer. This optical breakdown results from highly localized plasma in surrounding media where the nanoparticles stay intact. Also the impact of the gap distance, field polarization, laser fluence and pulse duration on the energy deposition in plasma is presented. These results can be used to make nanoscale plasmonic devices for variety of absorption-based applications.