**8.1 Silver nanoparticles incorporated into membrane and composite material**

Membrane and composite material-immobilized nanoparticles can have many functions including antimicrobial activity. Silver nanoparticles incorporated in membranes like polyethersulfone, acetate cellulose, polydopamine-coated poly(ether imide) etc. showed significant antimicrobial activity against diverse


#### **Table 1.**

*Silver nanoparticles based membrane composites for wound management.*

*Silver Micro-Nanoparticles - Properties, Synthesis, Characterization, and Applications*

In an average human concentration of silver in plasma is less than 2 μg/mL which

is derived from inhalation of particulate matter and diet [44]. Silver can enter human body by inhalation, oral ingestion and dermal absorption [34]. Pinocytosis and endocytosis are believed to be two processes by which the silver nanoparticles may enter the body. It is seen that the particles that are of nanoscale penetrate much deeper than those of regular size leading to a novel delivery therapy [47, 48]. Till now exact mechanism of action of silver nanoparticles is not clear but several actions have been proposed by the scientists for its antimicrobial activity. Continual release of silver ion is considered to be the main reason for its antimicrobial activity [49]. Due to sulfur protein affinity and electrostatic attraction silver ions adhere to the wall of cells and cytoplasmic membrane which increases its permeability and penetrability into the cytoplasmic membrane leading to disruption of the bacterial cell wall [50]. When the silver ion enters the cell it can deactivate the respiratory enzymes and can generate reactive oxygen species [51]. Reactive oxygen species acts as a key component and a major reason for cell membrane disruption and DNA damage (by interacting with sulfur and phosphorus of DNA) causing problem in DNA replication, reproduction results in death of the microbes. Silver ions also inhibit the synthesis of proteins by denaturation of ribosomes and cause interruption the production of ATP [52]. After anchoring the surface of the cell silver nanoparticles gets accumulated in the pits of the cellular wall of microbe resulting in cell membrane denaturation [53]. Due to nanosize they easily penetrate cell membrane, leading to rupture of cell organelles and even lysis. They also affect the bacterial transduction process by interfering with the phosphorylation of protein substrates which can result in cell apoptosis and cell multiplication [53, 54]. Gramnegative bacterial strains are more sensitive towards the effect of silver nanoparticles because the cellular walls of these bacteria are narrower than the gram positive bacteria [55]. One drawback of silver nanoparticles is that they are not much effective in the case of bacteria having biofilms. Biofilms protects the membrane from both nanoparticles and silver ions by altering their transport due to its complicated structure [56]. The pathway of the nanoparticles penetration is highly obstructed if the size is grater that 50 nm [57]. It is also observed that adsorption and accumulation of the silver nanoparticles on the biofilm results in reduced diffusion of

**6. Mechanistic insight of silver nanoparticles**

**132**

nanoparticles in bacteria [58].

**7. Silver nanoparticles wound dressings**

reduce any further chance of infection [62].

**8. Synthesis of silver nanoparticles for wound dressing**

A dressing is a sterile material applied to a wound to promote healing and protect the wound from further harm [59, 60]. It has been designed in such a way that it is in direct contact with the wound, as distinguished from a bandage, which is most often used to hold a dressing in place. Silver dressings are used for both types of wounds (acute and chronic) and when there is risk of high level of bio burden or local infection for example in the case of burns [61]. Silver dressings helps in reducing the bioburden in infected or colonized wounds and also acts as a barrier to

There are four types of silver nanoparticles synthesis, namely chemical, irradiation, green and thermal. In chemical synthesis, two types of synthesis methods are


#### **Table 2.**

*Silver nanoparticles incorporated clothing and dressings for wound management.*


**135**

**Figure 1.**

*Silver Nanoparticles Impregnated Wound Dressings: Recent Progress and Future Challenges*

healing process [78], representative examples are summarized in **Table 1**.

clothing and dressings. Representative examples are summarized in **Table 2**.

**8.2 Powdered silver nanoparticle and topical application**

range of microbes thus have capability to sterile wound environment and promote

Powdered silver nanoparticles are used for incorporation into different types of

Nanofibers are emerged as an important structures with wide range of biological as well as physical applications like air filtration, immunoanalysis and as pseudoenzymes etc. [81–84, 94, 95]. Apart from that active research is also ongoing for utilization of silver nanoparticles incorporated nanofibers for wound management.

Hydrogels have excellent capacity to absorb wound exudates and at the same time maintain the moisture in wound environment to ensure proper healing. Hydrogels form impermeable physical barrier on wound surface and prevent bacterial invasion (**Figure 1**) and apart from that hydrogels also showcased its tendency to absorb wide range of metals [59, 96, 107, 108]. Some silver nanoparticles incorporated hydrogels showed excellent wound healing activity as shown in **Table 4**.

Silver nanoparticles functionalized wound dressings have significant antimicrobial activity and provide faster and effective tissue repair thus they are widely

*Schematic layout of hydrogel membrane reducing bacterial invasion and accelerating wound healing process.*

*DOI: http://dx.doi.org/10.5772/intechopen.98731*

Examples of nanofibers are given in **Table 3**.

**8.3 Nanofibers**

**8.4 AgNPs-hydrogels**

**9. Future challenges**

#### **Table 3.**

*Silver nanoparticles incorporated nanofibers for wound management.*

range of microbes thus have capability to sterile wound environment and promote healing process [78], representative examples are summarized in **Table 1**.
