Metformin loaded silver nanoparticles were synthesized using ecofriendly method with extract of Azadiractha indica as reducing agent and two natural polymers; guar gum and xanthan gum, Sodium alginate, and a semi- synthetic polymer (AMS) as stabilizing agents.Twelve batches of nanoparticles were synthesized. Nanocomposites synthesized from AMS were designated as AMS 1% NANOmet, AMS3% NANOmet and AMS5% NANOmet. Guargum stabilized nanoparticles were designated as GG1% NANOmet, GG3% NANOmet and GG5% NANOmet while Xanthan gum nanocomposites were coded as XG1% NANOmet,XG3% NANOmet and XG5% NANOmet respectively. Sodium alginate stabilized nanocomposites were designated as NaALG1% NANOmet, NaALG3% NANOmet and NaALG5% NANOmet respectively. The percentage yield of nanocomposites was high with values ranging from 80 % to 99.87 %. The entrapment efficiencies of the samples ranged from 63.06 % to 80.22 % while the loading capacities were in the range of 7.24 % to 24.10%. Differential scanning calorimetry showed there was no interaction between the polymers and metformin. Characterization of the metformin nanocomposites using UV- visspectroscopy, zeta sizer, scanning electron microscopy (SEM) and polydispersity were performed. The UV-vis spectroscopy showed surface plasmon resonance of 371nm for all the nanocomposites except XG5%NANOmet which had SPR of 335nm. The mean particle sizeof GG1%NANOmet was ideal with a value of 188.7nm followed by AMS1%NANOmet(386.7 nm). All the batches showed extended and sustained release profile with initial burst effect at the first 30 min of release studies. Release of metformin in SIF was predominantly higher than in SGF. The kinetics of release was mainly zero order for all the nanocomposites with the exception of NaALG5% NANOmet which released the drug by higuchi kinetics.Antimicrobial property of the optimized nanocomposites were similar (P>0.05). Generally,MIC values of the samples against the microorganisms tested ranged from 2500- 5000μg/ml.16In vivo anti hyperglycemic property of the optimized metformin nanocomposite using glucose hyperload model results showed GG5%NANOmet as the optimum batch. At equal doses it produced sustained and consistent significant (p<0.001) decrease in elevated blood glucose level in glucose loaded hyperglycemic rats when compared with metformin and other nanocomposites treated groups.
In recent years, there has been an exponential interest in the development of novel drug delivery systems using nanoparticles . The transition from microparticles to nanoparticles has led to a number of changes in physical properties of materials . Two of the major factors in this are the increase in the ratio of surface area to volume, and the size of the particle moving into the realm quantum effects predominate. The increase in the surface-area-to volume ratio, which is a gradual progression as the particle gets smaller, leads to an increasing dominance of the behaviour of atoms on the surface of the particle over that of those in the interior of the particle. This affects both the properties of the particle in isolation and its interaction with other material. 
There have been tremendous developments in the field of Nanotechnology in recent time with various technologies formulated to synthesize nanoparticles with specific characteristics on morphology and distribution . Although, there are several methods for the synthesis of nanoparticles, they are very expensive and involve the use of toxic and hazardous chemicals which cause danger to humans and the environment . To overcome these challenges, the eco-friendly synthesis of nanoparticles using environmentally benign materials like Plants , microorganisms [4,5], seaweed  and enzymes  were employed.It is a single step and offers several advantages such as time reducing, cost effective and Nontoxic. Nanocrystalline silver is a known Noble metal and they have tremendous applications in the field of Detection, Diagnostics, Therapeutics and Antimicrobial activity .In general, nanoparticles offer significant advantages over the conventional drug delivery in terms of high stability, high specificity, high drug carrying capacity, ability for controlled release, possibility to use in different route of administration and the capability to deliver both hydrophilic and hydrophobic drug molecules .