## 1 Introduction  
Diabetic foot ulcer (DFU) is a major complication in patients with diabetic mellitus and causes substantial morbidity and increases mortality [1; 2]. Many patients are admitted in hospitals with DFU and their conditions get fatal when it progresses to life threatening diabetic foot infection (DFI) [3; 4]. Peripheral vascular disease and diabetic neuropathy are considered the most causative factors in DFU. They can act alone, together, or in combination with other factors such as biomechanical abnormalities, microvascular disease, increased susceptibility to infection, and limited joint mobility. A number of studies have found that _Staphylococcus aureus_ is mostly responsible pathogen for the DFU in the feet of the diabetic patients. From very recent findings, it has been shown that the predominance of Gram-negative aerobes (_P. aeruginosa_ and _Acinetobacter_ sp.) have major role in DFU [5; 6; 7; 8]. For many years, AgNPs and its metal complexes have been used extensively as antibacterial and wound healing agent due to their strong antimicrobial activity [9; 10; 11; 12; 13]. The bactericidal properties of the AgNPs have major advantages in the preparation of various silver containing topical agents for the treatment of chronic wounds. A variety of wound-healing agents, such as chlorhexidine aqueous solution and silver sulfadiazine cream, are currently being used to treat wounds. The AgNPs experience both shape and size dependent interactions with Gram-negative bacteria. The high surface to volume ratio of nanoparticles ensures that a significantly large surface area of the particles is in contact with the bacteria. Several studies have suggested that silver nanoparticles have the potential to treat human cancers, including leukemia [14]. Due to increased bacterial resistance to antibiotics, many diabetic patients do not heal properly. Bacterial resistance to commonly prescribed antibiotics--particularly quinolones (ciprofloxacin) and third generation cephalospororin (cefotaxime, ceftaxone)--was noticeable for the treatment of infected DFU [15]. High-valence silver nanoparticles are now considered as a possible substitute to antibiotics and appear to have a higher antimicrobial activity. It is also used to solve the problem of the emergence of bacterial multidrug resistance [16; 17]. Recently, [PERSON] et al. synthesized the high-valence silver salt bis(hydrogen periodato)argentite(III) complex and investigated the wound healing and antibacterial efficacy against _S. aureus_ and _P. aeruginosa_[18]. Our previous reports also suggested that high-valence silver nanoparticles showed stronger antibacterial activity than low-valence silver nanoparticles [19; 20; 21; 22]. Encouraged by these findings we thought to produce high-valence silver-based nanoparticles as antibacterial agent which would result in greater antimicrobial effectiveness against antibiotic resistant organisms. Silver metal exhibits in three oxidation states +1, +2, and +3 and can form complexes with suitable ligands. In this work, we attempted to synthesize high-valance nanosized Ag(II)PRO complex for higher antibacterial activity. Both AgNPs and Ag(II)PRO nanoparticles were synthesized in similar size and their antibacterial properties were compared. An aromatic diamidine compound propamidine is active against a number of protozoan organisms can inhibit the growth of bacteria in wounds. The antibacterial activity of propamidine was first reported in 1943 by [PERSON] et al. and used for the treatment of _Acanthamoeba_ keratitis and other corneal infections [23]. This polydiguanide molecule with silver can form silver polydiguanide complexes which have the potential to be used as a novel class of topical antimicrobial agent, particularly for the treatment of burn and wound infections. Polydiguanides possess conjugate single and double bond systems and filled _p_-type delocalized orbitals suitable for high-valence silver complex formation.