A new approach for microfluidics-based production of polymeric particles, namely two-photon continuous flow lithography, is reported. This technique takes advantage of two-photon lithography to create objects with sub-micrometer and 3D features, and overcomes the traditional process limitations of two-photon lithography by using multiple beam production under continuous flow. Polymeric fibers, helical and bow-tie particles with sub-diffraction resolution and surface roughness as low as 10 nm are demonstrated.

Fifth-generation ethylendiamine-core poly(amidoamine) (PAMAM G5)-capped gold nanoparticles were prepared by picosecond laser ablation in water, with the fundamental and second harmonic of a picosecond Nd:YAG laser. Although the visible wavelength exhibited a lower ablation threshold than that of the infrared one, the ablation process at 532 nm reached early saturation because of both linear and nonlinear absorption mechanisms, accompanied by fragmentation of existing nanoparticles. We demonstrate that the onset of the fragmentation can be monitored by simple UV−vis spectroscopy, thanks to the ability of PAMAM G5 to stabilize gold cations, which results in the growth of an intense band at 290 nm. We observed that, while with 532 nm (2.33 eV) irradiation a two-photon absorption mechanism induces fragmentation of the nanoparticles, the suspensions remain stable when irradiated with 1064 nm (1.17 eV) up to 60 GW/cm2.

Fifth generation ethylendiamine-core poly(amidoamine) (PAMAM G5) is presented as an efficient capping agent for the preparation of metal and semiconductor nanoparticles by ps laser ablation in water. In particular, we describe results obtained with the fundamental, second and third harmonic of a ps Nd:YAG laser and the influence of laser wavelength and pulse energy on gold particle production and subsequent photofragmentation. In this framework, the role of the dendrimer and, in particular, its interactions with gold clusters and cations are accounted.