Hindawi Publishing Corporation International Journal of Carbohydrate Chemistry Volume 2013, Article ID 539636, 10 pages http://dx.doi.org/10.1155/2013/539636 Research Article A Green Approach to Synthesize Silver Nanoparticles in Starch-co-Poly(acrylamide) Hydrogels by Tridax procumbens Leaf Extract and Their Antibacterial Activity Siraj Shaik,1 Madhusudana Rao Kummara,2 Sudhakar Poluru,1 Chandrababu Allu,1 Jaffer Mohiddin Gooty,3 Chowdoji Rao Kashayi,4 and Marata Chinna Subbarao Subha1 1 Department of Chemistry, Sri Krishnadevaraya University, Anantapur, Andhra Pradesh 515 003, India 2 DepartmentofPolymerScienceandEngineering,PusanNationalUniversity,Busan609-735,RepublicofKorea 3 DepartmentofMicrobiology,SriKrishnadevarayaUniversity,Anantapur,AndhraPradesh515003,India 4 Department of Polymer Science & Tech, Sri Krishnadevaraya University, Anantapur, Andhra Pradesh 515 003, India Correspondence should be addressed to Marata Chinna Subbarao Subha; [email protected] Received 31 August 2013; Accepted 13 November 2013 Academic Editor: Roland J. Pieters Copyright © 2013 Siraj Shaik et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A series of starch-co-poly(acrylamide) (starch-co-PAAm) hydrogels were synthesized by employing free radical redox poly- + merization. A novel green approach, Tridax procumbens (TD) leaf extract, was used for reduction of silver ions (Ag )into silver nanoparticles in the starch-co-PAAm hydrogel network. The formation of silver nanoparticles was confirmed byUV- visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (X-RD) studies. 22% of weight loss difference between hydrogel and silver nanocomposite hydrogel (SNCH) clearly indicates the formation of silver nanoparticles by TGA. TEM images indicate the successful incorporation of silver nanoparticles ranging from 5 to 10 nm in size and spherical in shape with a narrow size distribution. These developed SNCHs were used to study the antibacterial activity by inhibition zone method against gram-positive and gram-negative bacteria such as Bacillus and Escherichia coli. The results indicated that these SNCHs can be used potentially for biomedical applications. 1. Introduction forces that do not prevent the penetration of water through the network [5]. Based on these properties the hydrogels have Hydrogels have three-dimensional polymeric networks that been used recently as templates for production of metallic are fabricated from polymers stabilized through physical or nanoparticles. Hence the design and development of metal chemical crosslinking. They absorb large quantities of water nanoparticles dispersed in polymer matrix have attracted without losing their structural integrity [1]. Since they mimic potential applications in various fields like electrical, optical, body tissues and respond to external stimuli, they are made or mechanical properties [6, 7] making them valuable for important and promising forms of biomaterials for various applications in areas like optics [8], photo imaging and applications including tissue engineering, controlled drug patterning [9], electronic devices [10], sensors and biosensors release devices, biosensors, and mechanical actuators [2– [11–13], catalysis [14, 15], and antibacterial and antimicrobial 4]. Due to the presence of water solubilizing groups, such coatings [16]. Silver nanoparticles (Ag NPs) have attracted as –OH, –COOH, –CONH2,–CONH–,and–SO3H, these considerable interest in biological studies because of their hydrogels show higher hydrophilicity. The three-dimensional ease of preparation, good biocompatibility, and relatively network of hydrogel provides relative stability to its structure. large surface area [17, 18]. Ag NPs have many important appli- Their swollen state results from a balance between the cations in biomedical fields, sensors, and filters [19]. Addi- dispersing forces acting on hydrated chains and cohesive tionally, silver is a potential antibacterial agent [20]andis 2 International Journal of Carbohydrate Chemistry thus used as a sterilizer for removing bacteria from drinking The developed SNCHs may be biodegradable and nontoxic water [21, 22]. For economic and efficient use of silver, silver andwerepotentialmaterialstobeusedforbiomedical nanoparticle composites have been developed and tested for applications. antimicrobial activity. Starch is one of the natural, renewable, and biodegradable 2. Experimental polymers produced by many plants as a source of stored energy. Starch consists of two types of molecules: amylose 2.1. Materials. AR grade soluble starch (potato), silver nitrate (normally 20–30%) and amylopectin (normally 70–80%). (AgNO3), potassium persulfate (KPS), maleic acid (MA), and The relative proportion of amylose to amylopectin depends sodium hydroxide (NaOH) were purchased from SD Fine 1 onthesourceofstarch.Itisversatileandcheapandhas Chemicals,Mumbai,India.Acrylamide(AAm),, -meth- 1 11 many uses as thickener, water binder, emulsion stabilizer, and ylenebisacrylamide (MBA), and ,, , -tetramethyl- gelling agent [23]. Starch granules are insoluble in cold water ethylenediamine (TEMED) were purchased from Aldrich but imbibe water reversibly and swell slightly [24]. Maleic Chemical Company Inc. (Milwaukee, WI, USA). All chem- acid (MA) is a nontoxic and biodegradable hydrophilic icals were used without further purification. Double-distilled substance which is used as a type of food additive in (DD) water is used throughout the experiment. processing industry. The modification of starch with MA increases its hydrophilicity by converting it into ester form by the reaction between starch and MA to form starch macro- 2.2. Preparation of Tridax procumbens (TD) Leaf Extract. monomer [25]. The chemical modification of starch with MA Leaf extracts were prepared by a green process technique, and tartaric acid improves its properties without sacrificing using the standard procedure described by Prasad et al. [39]. its biodegradability and biocompatibility [25–27]. Several Tridax procumbens leaves were collected from Tridax pro- reports are present on acrylamide (AAm) hydrogels that were cumbens plants at our university campus in Sri Krishnade- developed because of their hydrophilic and inert nature that varaya University (Anantapur, Andhra Pradesh, India), thor- makes them suitable for applications in medicine and phar- oughly washed with DD water to remove the dust particles, macy [28, 29].Polyacrylamidehasbeenusedincontactlenses and then dried in sun to remove the residual moisture. From for a long time, and it has well been evaluated as a sustained- this 20 g leaves were chopped finely and boiled in a 250 mL release wound-dressing material [30]. glass beaker along with 200 mL of sterile DD water for 10 min In continuation of our work [31]onusageofpoly- in order to extract the contents of the leaves. After boiling the mers in biomedical applications, the present research paper colour, the aqueous solution changed from watery to yellow explores a simple and facile method to synthesize starch- colour. The aqueous extract was separated by filtration with co-poly(acrylamide) (starch-co-PAAm) hydrogels and silver 2.5 m Whatman filter paper (Sigma-Aldrich, USA) and then nanocomposite hydrogels (SNCHs) by using a green process stored at room temperature. + in which the Ag ions are successfully reduced by Tridax procumbens (TD) leaf extract. Starch, MA, and AAm were 2.3. Synthesis of Starch-co-PAAm Hydrogels and Their Sil- chosen on the basis of their significant characteristics in ver Nanocomposite Hydrogels (SNCHs). Gelatinized starch biomedical fields. The most popular way used for the direct solution was prepared by mixing a quantitative amount of synthesis of metal ions into nanoparticles is through chemical starch powder in 10.0 mL of DD water and 1.0 mL of 0.5 M reductionmethodbyusingseveralreagentssuchassodium sodium hydroxide (NaOH) solution, and the mixture was ∘ borohydride, sodium hypophosphite, and sodium citrate. heated in a water bath at 90 Cfor10minwithcontinuous Several reports are presented for the development of Ag NPs magnetic stirring. A predetermined amount of MA was then by using such reducing agents [32, 33]. But these reducing added to the gelatinized starch solution and the resulting agents may have environmental problems due to their tox- ∘ mixturewasfurtherheatedinawaterbathat80Cfor4h icity, so a considerable interest to use nontoxic materials for [25]. Subsequently, a quantitative amount of acrylamide was reduction of Ag NPs is growing rapidly these days. In order to ∘ added and stirred for half an hour at 50 C, after that cross- avoid such type of toxic reagents, recently plant extracts have beenusedforproductionofAgNPsduetotheircost-effective linker (MBA) and initiator (KPS) were added according to the nature and also ambient conditions for reduction [34–37]. formulations mentioned in the Table 1.Finally,anaqueous Therefore, the development of metal nanoparticles based on solution of TEMED was added to the solution and the same natural extracts is considered the most appropriate method. temperature was maintained for another 10 min. After Recently Tridax procumbens (TD) leaf extract was used as completion of free radical polymerization, the synthesized reducing agent for preparation