Unique characteristics of SERS including the possibility to reveal the compositional and structural content of trace amounts of biological samples without any pre‐treatment, depict this technique as a promising label‐free alternative to standard analytical methods. Despite significant advancements, current SERS substrates for biomolecule detection suffer from a number of issues still impeding their routine usage and commercial exploitation, including complex and expensive fabrication procedures and scarce standardization perspectives. Herein a combined bottom up/top down scheme based on flow‐through method plus laser patterning is proposed to prepare dot arrays of silver nanowires on a hydrophobic substrate for catching the analyte content from a minute amount of liquid sample and its rapid SERS inspection. As a consequence, a simple spot‐on analysis specifically adapted for reliable identification and characterization of molecules of biomedical interest is made possible. Our attempt may represent a concrete chance for progressing SERS toward widespread commercially viable sensing applications including diagnostics at the point‐of‐need settings and on‐site analyses.

In the present work, we focus on the assessment of the chemical and physical side effects induced by UV laser ablation of varnish samples (i.e. mastic, oil-mastic, dammar, and bleached shellac) after natural curing and artificial ageing using micro-Raman spectroscopy, laser-induced fluorescence and environmental scanning electron microscopy. The varnish films were irradiated with the fifth (213 nm) and fourth (266 nm) harmonics of a Q-switched Nd: YAG laser. Besides the systematic microscopy inspection of the irradiated areas, a significant effort was devoted to the study of the optical properties of the varnish films by means of UV-Vis absorption spectroscopy, which allowed the determination of linear absorption coefficients at the present laser irradiation wavelengths. Single-pulse laser ablation thresholds were measured by applying the spot regression method, and processing of the films was carried out using three different scanning speeds that resulted in 1, 5, and 10 laser pulses on each irradiated area. The results achieved using laser fluences well above the single-pulse ablation threshold of the treated varnishes, indicated that the quality of the material removal process crucially depends on the irradiation wavelength, type of varnish, and on its degree of polymerization. In contrast with the undesired modifications observed at 266 nm, that led to the formation of microbubbles, which produced a whitish appearance of the irradiated area, the absence of relevant side effect at 213 nm emphasizes the importance of using a highly absorbed wavelength to finely remove the altered uppermost layer of different types of aged varnishes.Peer Reviewe

In this work, laser ablation has been applied for removing overpaint found on the reverse of a signed easel painting by Giacomo Balla, one of the founding members of the Futurist movement. After unsuccessful attempts to remove the overpaint layers selectively using organic solvents, a long Q-switched Nd:YAG laser (1064 nm, 120 ns) ablation was successfully trialled, enabling the planning of complete uncovering of a hidden artwork by laser treatment. Laser cleaning was accompanied with a thorough characterisation of the original pigments, binders, and overpaint using Raman and FTIR spectroscopy, along with stratigraphic examination combined with optical and ESEM-EDX analysis. In parallel systematic experimentation on samples simulating the layers to be removed was carried out to interpret the laser removal processes being exploited and fine-tune the treatment.