**5. Conclusions**

In this review, we focused on AgNPs, a very useful nanomaterial for active food packaging, paying particular attention to AgNPs synthetized by LASiS. After brief overviews of bioactivity pathways of AgNPs and of synthesis methods to produce silver nanocolloids, we focused on the LASiS method, describing in detail its working principles and the influence of the main laser parameters

on the production yield and quality. A short overview of the use of AgNPs in food packaging was also proposed. Laser ablation is a green technique to produce stable Ag nanocolloids in a wide variety of dispersing media without using metal precursors and reductants. Highly pure colloids are produced with unique surface characteristics and without any by-products. These features, in principle, make AgNPs produced by LASiS some of the best candidates for antimicrobial applications. However, to date, the productivity is insufficient for direct use in the industrial sector. The current world record for LASiS NP productivity is 4 g/h; this value, although appealing, needs to be improved for LASiS to be used in the industrial sector. Methods to increase this productivity level are currently under development, exploiting high scanning speeds. This way, laser-induced cavitation bubbles are spatially bypassed at high repetition rates, and continuous multi-gram ablation rates have been already demonstrated for platinum, gold, silver, aluminum, copper, and titanium. LASiS requires a grea<sup>t</sup> amount of energy, and its scaling-up at the industrial production level is approaching the efficiency required for real-life applications, although there is still a need of for further technological improvement, mostly with regard to the technological laser solutions.

**Author Contributions:** M.C.S. and M.I. performed bibliographic research and wrote the first draft of the paper. A.V., M.C., R.A.P., A.A., P.M.L., G.P., and N.C. took part in scientific discussions and contributed to different sections of this review. A.A. and N.C. coordinated and revised the study.

**Funding:** This research was partially funded by: by Italian MIUR Project, gran<sup>t</sup> number #PONa3 00369.

**Acknowledgments:** The authors gratefully acknowledge the Apulian Region and the Italian Ministry of Education, University and Research for having supported this research activity within the projects MICROTRONIC (Lab Network cod. 71) and "Reti di Laboratori Pubblici di Ricerca" (Lab Network cod. 56).

**Conflicts of Interest:** The authors declare no conflict of interest.
