Formation of gold/silver composite nanoparticles by pulsed laser ablation of gold–silver layered films in liquid

Nanoparticles of high purity can be produced from a variety of materials by pulsed laser ablation of solids in liquid. Composite nanoparticles are of great importance in various applications such as catalysis or biomedicine and the process of their formation is still a subject of intense research. In this work, gold/silver composite nanoparticles were synthesized in aqueous media by ns pulsed laser ablation of gold–silver multilayer targets with different absolute layer thicknesses and layer thickness ratios. The generated nanoparticles showed a log-normal distribution of sizes, with average diameter in the 20–40 nm range and standard deviation of 9–30 nm. By comparing the UV–VIS absorbance spectra of the nanoparticle colloids with two theoretical calculations (based on the Mie and the BEM model), it was found that there is a direct correlation between the average Au and Ag content of the nanoparticles and the composition of the films on the substrate. Assuming thermal ablation, our model calculations showed that there is a maximum thickness of the top layer up to which both layers can be ablated simultaneously and alloy nanoparticles can be produced

Application of pulsed laser ablation (pLA) for the size reduction of non‑steroidal anti‑inflammatory drugs (nSAiDs)

We studied the application of pulsed laser ablation (pLA) for particle size reduction in non‑steroidal anti‑inflammatory drugs (NSAIDs). Grinding of the poorly water‑soluble NSAID crystallites can considerably increase their solubility and bioavailability, thereby the necessary doses can be reduced significantly. We used tablets of ibuprofen, niflumic acid and meloxicam as targets. Nanosecond laser pulses were applied at various wavelengths (KrF excimer laser, λ=248 nm, FWHM=18 ns and Nd:YAG laser, λ1=532 nm/λ2=1064 nm, FWHM=6 ns) and at various fluences. FTIR and Raman spectra showed that the chemical compositions of the drugs had not changed during ablation at 532 nm and 1064 nm laser wavelengths.The size distribution of the ablated products was established using two types of particle size analyzers (SMPS and OPC) having complementary measuring ranges.The mean size of the drug crystallites decreased from the initial 30–80 µm to the submicron to nanometer range. For a better understanding of the ablation mechanism we made several investigations (SEM, Ellipsometry, Fast photography) and some model calculations. We have established that PLA offers a chemical‑free and simple method for the size reduction of poorly water‑soluble drugs and a possible new way for pharmaceutical drug preformulation for nasal administration