Miguel A. Camacho-López

Multifunctional targeted therapy system based on 99mTc/177Lu-labeled gold nanoparticles-Tat(49–57)-Lys3-bombesin internalized in nuclei of prostate cancer cells

Radiolabeled gold nanoparticles may function simultaneously as radiotherapy and thermal ablation systems. The gastrin-releasing peptide receptor (GRP-r) is overexpressed in prostate cancer, and Lys(3) -bombesin is a peptide that binds with high affinity to the GRP-r. HIV Tat(49-57) is a cell-penetrating peptide that reaches the DNA. In cancer cells, (177) Lu shows efficient crossfire effect, whereas (99m) Tc that is internalized in the cancer cell nuclei acts as an effective system of targeted radiotherapy because of the biological Auger effect. The aim of this research was to evaluate the in vitro potential of (99m) Tc-labeled and (177) Lu-labeled gold nanoparticles conjugated to Tat(49-57)-Lys(3) -bombesin peptides ((99m) Tc/(177) Lu-AuNP-Tat-BN) as a plasmonic photothermal therapy and targeted radiotherapy system in PC3 prostate cancer cells. Peptides were conjugated to AuNPs (5 nm) by spontaneous reaction with the thiol group of cysteine (Cys). The effect on PC3 cell viability after laser heating of the AuNP-Tat-BN incubated with the cancer cells was conducted using an Nd:YAG laser pulsed for 5 ns at 532 nm (0.65 W/cm(2) ). For the (99m) Tc/(177) Lu-AuNP-Tat-BN to be obtained, the (177) Lu-DOTA-Gly-Gly-Cys and (99m) Tc-HYNIC-octreotide radiopeptides were first prepared and added simultaneously to a solution of AuNP-Tat-BN. (99m) Tc/(177) Lu-AuNP-Tat-BN (20 Bq/cell) was incubated with PC3 cells, and the effect on the cell proliferation was evaluated after 3 days. Fluorescence images of (99m) Tc/(177) Lu-AuNP-Tat-BN internalized in nuclei of PC3 were also obtained. After laser irradiation, the presence of AuNP-Tat-BN caused a significant increase in the temperature of the medium (46.4 vs 39.5 °C of that without AuNP) resulting in a significant decrease in PC3 cell viability down to 1.3%. After treatment with (99m) Tc/(177) Lu-AuNP-Tat-BN, the PC3 cell proliferation was inhibited. The nanosystem exhibited properties suitable for plasmonic photothermal therapy and targeted radiotherapy in the treatment of prostate cancer.

Laser Heating of Gold Nanospheres Functionalized with Octreotide: In Vitro Effect on HeLa Cell Viability

OBJECTIVE The aim of this study was to assess the effect of laser heating a well-characterized gold nanoparticle (AuNP)-octreotide system on HeLa cell viability, to evaluate its potential as a suitable agent for plasmonic photothermal therapy. BACKGROUND DATA Octreotide is a synthetic peptide derivative of somatostatin with an effect on the survival of HeLa cells. Peptides bound to AuNPs are biocompatible and stable multimeric systems with target-specific molecular recognition. METHODS Octreotide was conjugated to AuNPs (∼20 nm) by spontaneous reaction with the thiol groups. The nanoconjugate was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet visible spectroscopy (UV-Vis), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Irradiation experiments were conducted using an Nd:YAG laser pulsed for 5 ns at 532 nm with a repetition rate of 10 Hz for up to 6 min while delivering an average irradiance of 0.65 W/cm(2). HeLa cells were incubated at 37°C (1) with AuNP-citrate, (2) with AuNP-octreotide, or (3) without nanoparticles. RESULTS After laser irradiation, the presence of AuNP caused a significant increase in the temperature of the medium (48°C vs. 38.3°C of that without AuNP). The AuNP-octreotide system resulted in a significant decrease in cell viability of up to 6 % compared with the AuNP-citrate system (15.8±2.1%). Two possible mechanisms could be at play: (1) octreotide alone exerts an effect on survival HeLa cells, or (2) the release of heat (∼727°C per nanoparticle) in the membranes or cytoplasm of the cells caused by the interaction between AuNP-octreotide and somatostatin receptors reduced viability. CONCLUSIONS The AuNP-octreotide system exhibited properties suitable for plasmonic photothermal therapy in the treatment of cervical cancer.

Growth of rutile TiO2 thin films by laser ablation

AbstractThin films of TiO2 on glass substrates were grown by the laser ablation technique using the second harmonic (532 nm) of a pulsed Nd–YAG laser as the evaporation source. During deposition, various substrate temperatures and oxygen pressures were used to optimise the growth of rutile TiO2 thin films. Raman spectroscopy and X-ray diffraction measurements showed that crystalline thin films were obtained at a substrate temperature as low as 100°C. The films show smooth surface morphology and good adhesion.

a-C thin film deposition by laser ablation

d ´ Abstract The plasma formed during the laser ablation of a carbon target has been studied by optical emission spectroscopy and Langmuir electrostatic probes in order to investigate the kinetic energy of the ions, and the plasma density as a function of the target-to- substrate distance and the laser intensity.The experiments were carried out using a Nd:YAG laser with emission at the fundamental line, with a maximum energy output of 150 mJ.In our experimental conditions the plasma emission is principally due to C q (283.66, 290.6, 299.2 and 426.65 nm) and C (406.89 and 418.66 nm).The ion energies detected varied in a wide range, from 2q

Raman studies on laser induced crystallization of Co(II) doped titania; effect of the dopant concentration

Abstract Crystallization induced by continuous laser irradiation at 514.5 nm on Co(II)-doped titania matrices prepared by sol–gel process, is reported for different Co(II) concentrations. The cobalt ions improve the energy absorption at this wavelength, reducing the laser power required to induce the amorphous to anatase or rutile phase transition in the titania as the Co concentration increases. The crystallization threshold (the minimum laser power to induce the phase transition) was determined for the different cobalt concentrations. Crystallization kinetics was monitored in real time by Raman spectroscopy and analyzed using a simple model.

Processing of Metallic Thin Films Using Nd:YAG Laser Pulses

Nd:YAG lasers are possibly the more widely used lasers either for basic research or for industrial and technological applications (Dubey, A. K. & Yadava, V. 2008). These lasers are also excellent pump sources for laser development, for instance Ti:sapphire ultrashort pulse lasers are based on CW Nd:YAG pumping. In particular, Nd-YAG lasers have been applied to study laser-induced oxidation in metals as titanium and chromium; semiconductors as silicon (Aygun, G. et al., 2006). (Perez del Pino, A. et al., 2004) demonstrated that the rutile phase of TiO2 is obtained by laser oxidation in air of titanium films. Nd:YAG laser pulses have been used to laser-induce a phase transformation from W3O thin films to WO3 (Evans R., et al., 2007); laser ablation for micromachining of bulk metals as copper, bronze and aluminum has also been done using Nd:YAG nanosecond pulses (Maisterrena-Epstein R., et al., 2007); laser-induced oxidation and novel LIPSS formation in titanium thin films deposited on silicon substrates was demonstrated by using a single laser beam from a frequency doubled Nd:YAG nanosecond pulsed laser (Camacho-Lopez S., et al., 2008). Some works about pulsed laser oxidation have been reported (Dong, Q. et al., 2002). (Pereira, A. et al. 2004) have investigated the laser treatment in steel irradiating at various wavelengths by using different laser sources. In Table 1, we cited some works on the oxidation induced by pulsed laser irradiation in various metals. Recently, we have published results on fs-laser

Determination of the Residual Anthracene Concentration in Cultures of Haloalkalitolerant Actinomycetes by Excitation Fluorescence, Emission Fluorescence, and Synchronous Fluorescence: Comparative Study

Polycyclic aromatic hydrocarbons (PAHs) are compounds that can be quantified by fluorescence due to their high quantum yield. Haloalkalitolerant bacteria tolerate wide concentration ranges of NaCl and pH. They are potentially useful in the PAHs bioremediation of saline environments. However, it is known that salinity of the sample affects fluorescence signal regardless of the method. The objective of this work was to carry out a comparative study based on the sensitivity, linearity, and detection limits of the excitation, emission, and synchronous fluorescence methods, during the quantification of the residual anthracene concentration from the following haloalkalitolerant actinomycetes cultures Kocuria rosea, Kocuria palustris, Microbacterium testaceum, and 4 strains of Nocardia farcinica, in order to establish the proper fluorescence method to study the PAHs biodegrading capacity of haloalkalitolerant actinobacteria. The study demonstrated statistical differences among the strains and among the fluorescence methods regarding the anthracene residual concentration. The results showed that excitation and emission fluorescence methods performed very similarly but sensitivity in excitation fluorescence is slightly higher. Synchronous fluorescence using Δλ = 150 nm is not the most convenient method. Therefore we propose the excitation fluorescence as the fluorescence method to be used in the study of the PAHs biodegrading capacity of haloalkalitolerant actinomycetes.

Optical properties of TiO2-x thin films studied by spectroscopic ellipsometry: substrate temperature effect

Titanium oxide thin films were obtained by reactive dc-magnetron sputtering. A target of titanium (Lesker; 99.9% pure) and a mixture of argon and oxygen gases were used to deposit titanium oxide films onto silicon and glass substrates. The substrate temperature was varied between 200 and 400°C. Optical constants have been determined by spectroscopic ellipsometry and by using the optical transmittance data from UV-Vis spectrometry. The effect of substrate temperature on the optical properties is analyzed. Results indicate an increase in the refractive index of the films with substrate temperature, which is attributed to changes in the oxygen content, density and degree of crystallization of the films.

Investigation of EBT3 radiochromic film's response to humidity

Abstract Purpose The aim of this work is to investigate the effects of immersing EBT3 radiochromic film in water and to evaluate its contribution to the total uncertainty in dose determination. Materials and methods We used 3 cm × 3 cm EBT3 radiochromic films irradiated in the range of 0–70 Gy to study the impact of water immersion on the change in net optical density. These films were placed in a water container for a period of 24 h. The net optical density was measured before (0 h) and after of the immersion in water (1, 3, 6, 12, 18, and 24 h). The absorbance spectrum of the EBT3 radiochromic film was measured at 0 h and 24 h after immersion in water. The uncertainty in dose determination due to the effects of keeping the EBT3 radiochromic film submerged in water at 0, 1, and 24 h were recorded in the red, green, and blue channels. Results We observed an increase in the net optical density as an effect on the film due to its immersion in water. The penetration of the water at the edges of the radiochromic film was observed to be a function of time during which the film remained in the water. On the other hand, the penetration of water at the edges of the film was found to be independent of irradiation dose. Conclusions EBT3 radiochromic film is found more resistant to water penetration through the edges than its predecessors. However, there is evidence that suggest that liquid water damage the Nylon cover layer of the film by changing its optical properties. Therefore, it is recommended to build a new calibration curve for radiochromic films for a specific situation involving dose measurements in liquid water.

Laser-induced periodic surface structures on bismuth thin films with ns laser pulses below ablation threshold

We demonstrate the formation of laser-induced periodic surface structures (LIPSS) in bismuth (Bi) thin films by irradiation with nanosecond laser pulses. We report on the formation and the destruction of the LIPSS as a result of the delivered number of pulses; both the formation and destruction threshold were very well determined. Results show that the obtained LIPSS are perpendicular to the laser polarization, and their ripple periodicity is on the order of the irradiation wavelength. Although all the irradiation experiments were done in ambient air, Raman micro-spectroscopy indicates that the LIPSS are constituted by metallic bismuth, i. e. the LIPSS formation is oxidation free.