**5. Conclusion and future perspectives**

occur simultaneously onto the surface of the material because the photo-reduction reaction induced by UV irradiation determines the conversion from the silver precursor to metal silver nanoparticles. The silver coatings deposited are characterized by a strong adhesion to the substrate, good antimicrobial capability and biocompatibility and low silver release [109]. Cotton gauzes treated with low amounts of silver have demonstrated good antimicrobial activity against different bacterial strains and fungi, and the good antibacterial properties were further confirmed in simulated working conditions such as after incubation in artificial exudate inoculated with bacteria [110]. **Figure 1** reports the agar diffusion test performed on untreated gauze and gauze treated with silver by adopting the technology described using *Staphylococcus*

**Figure 1.** Agar diffusion tests on untreated gauze and cotton gauze treated by photo-reduction technology.

Silver nylon cloth/activated charcoal. Most type of chronic wounds and infected

**Description of the product Application References**

Low to moderate exuding acute and chronic

Acute and chronic wounds at risk of infection, with moderate and abundant exudate.

Infected ulcers, surgical wounds and burns. [87, 112]

[112, 113]

[112, 113]

[112, 114]

wound at risk of infection.

wounds and ulcers.

Although the impregnating silver solution was prepared by using a percentage of silver lower than 0.5 wt/v%, the antibacterial test clearly demonstrated that the presence of the silver coating successfully inhibited the bacterial growth beneath and around the sample, thus indicating a good potential of product as antibacterial wound dressing. Also flax substrates have been treated with silver by adopting the same technology and the microbiological activity was still confirmed after industrial washing, thus suggesting the excellent stability of the

*aureus* as tester microorganism.

444 Wound Healing - New insights into Ancient Challenges

Polyester textile mesh impregnated with hydrocolloid

Sodium carboxymethylcellulose hydrofibres combined

Flexible polyethylene cloth coated with nanocrystalline

**Table 2.** Examples of commercial silver-containing dressings.

particles, vaseline and silver sulphate.

with ionic silver.

Ag particles.

Nanotechnology is gaining huge impetus in the present century due to the drastic changes of chemical, physical and optical properties of metals at nanoscale size [84]. The cutting-edge combination of nanotechnology with medicine offers unprecedented opportunities to revolutionize currently available macro-scale therapeutics. Nanoparticles-based delivery systems can be highly beneficial to improve the therapeutic power of biological and synthetic molecules [90]. Due to the knowledge of cellular and molecular processes underlying wound healing, the new therapeutic approaches act directly on cellular and subcellular events during the healing process [90].

In recent years, metal nanoparticles/polymer composites have created lot of attraction due to their wide range of applications [41]. The interest in broad-spectrum antimicrobial agents is particularly increasing for medicated wound dressings, in order to control colonization of wounds by opportunistic pathogens. Medicated wound dressings have demonstrated efficacy *in vitro* against planktonic microorganisms; however, *in vivo* bacteria are organized in biofilms, which is more challenging to control and eradicate [116]. Silver nanoparticles, in particular, have been identified as potent antimicrobial agent and are being evaluated in different medical applications ranging from silver based dressings to silver coated medical devices [117]. Silver in ionized form or nanoparticles exhibits excellent antimicrobial and antifungal properties and efficacy in preventing biofilm formation by pathogenic bacteria. Silver-based wound dressings are widely used in clinical practice and show promising results in healing of contaminated wounds [118].

Despite its recognized importance, there have not been systemic studies that probe the targeting efficiency of nanoparticles nor international standards on their toxicology and biocompatibility [119]. Despite their promise, further studies are needed to elucidate the pharmacokinetics of nanoparticles and potential for *in vivo* toxicity. However, to date, studies have found limited toxicity without evidence of systemic absorption [120].
