The incorporation of Ag NPs into a gel matrix has been used as a strategy to retain their antimicrobial proprieties at the site of administration and it has allowed the development of wound dressings with demonstrated high efficacy against a wide spectrum of bacteria, including S. aureus, methicillin-resistant S. aureus (MRSA), E. coli, and P. aeruginosa. Notably, these hydrogel dressings have proven to be equally or even more effective than commercial formulations (e.g., Ag gels, fusidic acid cream, Tegaderm ® dressing, mupirocin solution). Similarly, cuprous oxide NPs and bismuth oxychloride were embedded in ALG resulting in a fluid formulation that perfectly filled dental pits and fissures.