# Review on Silver Nanoparticles as a Novel Class of Antibacterial Solutions
## 1 Introduction  
Nanotechnology is a field of technology that works with materials presenting at least one dimension ranging between 1 nm and 100 nm for the purpose of obtaining new materials and objects. Nano materials are very different when compared with macroscopic materials, because of their unique, superior and indispensable properties, and they have recently became a research focus due to their distinct characteristics. One of the key differences is their high surface-to-volume ratio as well as an increased number of atoms present in grain boundaries. Due to their unique properties and qualities, nanomaterials are an important part of developing new devices which can be used in many fields such as: medicine, physics, biology, biomedicine, pharmacy, cosmetics and various product industries [1]. Recently, nanotechnology has proven great potential and efficient results in treating bacterial infections. In 1870, English doctor [PERSON] discovered a connection between mold and bacteria cultivation. Soon after, in 1928, the accidental discovery of penicillin is attributed to [PERSON]. Penicillin was first used in 1942, having a huge impact on antibacterial treatment because up to that moment, most infectious diseases were deadly. When penicillin started to be used, it had an effect against Gram positive bacteria. Nowadays, a lot of bacteria strains have become immune due to the irrational use of antibiotics.  
Following the first reports, various drugs have been developed, exerting antibacterial, antifungal and antiviral properties with great life-saving impact. Excessive use of antibiotics had two major effects: first, it led to a higher microbial resistance and second, to the appearance of multiresistant bacteria, endangering the lives of many patients. Animmediate consequence was a need to develop further technologies to allow the generation of new substances with antibacterial properties while maintaining low toxicity levels suitable for applications in medicine. The latest antibacterial drugs have been developed around 1980s. Since then, no significant discovery was reported. Vancomycin is one of the first antibiotics that have been used in infections treatment against methicillin resistant _Staphylococcus aureus_ for more than 50 years. The evolution of bacteria in time leads to more Vancomycin-resistant strains appearance. As a consequence, there is a constant need for the development of new drugs. One possible concept of drug improvement is effect enhancement by means of nanoparticles, thus allowing the binding of metals, proteins, phospholipids and antibodies [2].  
Materials such as metal nanoparticles [3], metal oxide nanoparticles [4], carbon nanomaterials [5] and their composites have been intensively used as new antibacterial agents as a result of their small sizes, unique chemical and physical properties, and high specific surface. Silver nanoparticles proved to have unique antibacterial properties which resulted in their extensive use in fields such as: biomedicine, pharmacy or cosmetic industry [6]. Excellent antimicrobial properties, lowered toxicity and better biocompatibility have been reported to be exerted by silver nanoparticles, as compared to other metallic particles. The observations and data on the broad-spectrum antibacterial nature of AgNPs have been providing a fundament for more antibacterial-oriented applications. It has even been recently reported that Ag nanoparticles have an increased ability to inhibit bacterial growth as compared to antibiotics and that no or limited side effects are induced by AgNPs exposure [1; 6].