Journal name: International Journal of Nanomedicine Article Designation: Original Research Year: 2015 Volume: 10 (Suppl 1: Challenges in biomaterials research) International Journal of Nanomedicine Dovepress Running head verso: Balashanmugam and Kalaichelvan Running head recto: Synthesis of silver nanoparticles using Cassia roxburghii DC. open access to scientific and medical research DOI: http://dx.doi.org/10.2147/IJN.S79984 Open Access Full Text Article ORIGINAL RESEARCH Biosynthesis characterization of silver nanoparticles using Cassia roxburghii DC. aqueous extract, and coated on cotton cloth for effective antibacterial activity Pannerselvam Abstract: The present study reports the green synthesis of silver nanoparticles (AgNPs) from Balashanmugam silver precursor using a plant biomaterial, Cassia roxburghii DC., aqueous extract. The AgNPs Pudupalayam Thangavelu were synthesized from the shade-dried leaf extract and assessed for their stability; they elucidated Kalaichelvan characteristics under UV–visible spectroscopy, X-ray diffraction, Fourier transform infrared spec- troscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray spectros- Centre for Advanced Studies in Botany, University of Madras, Chennai, copy. The synthesized AgNPs exhibited a maximum absorption at 430 nm, and the X-ray diffraction India patterns showed that they were crystal in nature. Fourier transform infrared spectroscopy analysis confirmed the conversion of Ag+ ions to AgNPs due to the reduction by capping material of plant extract. The HR-TEM analysis revealed that they are spherical ranging from 10 nm to 30 nm. The spot EDAX analysis showed the presence of silver atoms. In addition, AgNPs were evaluated for their antibacterial activity against six different pathogenic bacteria: three Gram-positive bacteria, Bacillus subtilis, Staphylococcus aureus, and Micrococcus luteus, and three Gram-negative bac- teria, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter aerogenes. They were highly sensitive to AgNPs, whereas less sensitive to AgNO3. Furthermore, the green synthesized AgNPs were immobilized on cotton fabrics and screened for antibacterial activity. The immobilized AgNPs on cotton cloth showed high antibacterial activity. Therefore, they could be a feasible alternative source in treating wounds or may help in replacing pharmaceutical band-aids. Keywords: bioreduction, stability, immobilization, cotton cloth, minimum inhibitory concentration Introduction Nanomaterials are at the leading edge of the rapidly developing field in nanotechnology. Their unique size makes them superior and indispensible in many areas of human activ- ity. Nanotechnology encompasses the production and application of physical, chemical, and biological systems at scales ranging from individual atoms or molecules to submi- cron dimensions, as well as the integration of the resulting nanostructures into larger systems. Science and technology research in nanotechnology promises breakthroughs in areas such as materials and manufacturing, nanoelectronics, medicine and health care, energy, biotechnology, and information technology. Nanoparticles are usually Correspondence: Pannerselvam referred to as the particles with a maximum size of 100 nm. Nanoparticles exhibit new Balashanmugam properties when compared to larger particles of the bulk material. The novel properties Centre for Advanced Studies in Botany, University of Madras, Guindy Campus, are derived due to the variations in specific characteristics, such as size, distribution, Chennai 600 025, India and morphology of particles. The nanoparticles have a wide range of applications, Tel +91 999 463 3730 Email [email protected] such as in combating microbes, drug delivery, catalysis,1 water purification,2 treatment submit your manuscript | www.dovepress.com International Journal of Nanomedicine 2015:10 (Suppl 1: Challenges in biomaterials research) 87–97 87 Dovepress © 2015 Balashanmugam and Kalaichelvan. This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution – Non Commercial (unported, v3.0) License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further http://dx.doi.org/10.2147/IJN.S79984 permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php Balashanmugam and Kalaichelvan Dovepress of environmental waste,3 food industry,4,5 textile industry,6,7 hepatoprotective activity.20 It is also being used in in vivo biolabeling, and treatment of cancer. wound healing.21 In the present study, AgNPs were synthe- Generally, metal nanoparticles can be prepared and sized from C. roxburghii. They were characterized using stabilized by physical and chemical methods. The chemical high-resolution transmission electron microscopy, energy approaches, such as chemical reduction, electrochemical dispersive X-ray (EDX) spectroscopy, Fourier transform techniques, lithography, and photochemical reduction, are infrared spectroscopy (FTIR), and X-ray diffraction (XRD) most widely used.8,9 Though they have the control over the analysis. The antibacterial activity of AgNPs and AgNPs size and shape of the nanoparticles, they pose some threats coated on cotton fabric was investigated against six differ- when they are being used in the medical applications. ent pathogenic bacteria. Moreover, they are expensive, need high pressure, energy, and temperature, and need use of some toxic chemicals for Materials and methods the stabilization of nanoparticles, leading to adverse effects All the analytical grade chemicals were purchased from when they are being applied in the medical and pharmaceuti- Sigma-Aldrich Co. (St Louis, MO, USA). Silver nitrate was cal applications;10 hence, there is an increasing need for the purchased from HiMedia Laboratories (Mumbai, India). The development of an eco-friendly process for the synthesis bacteria were obtained from the Culture Collection Facility of nanoparticles. Plants have attracted more attention than at the Centre for Advanced Studies in Botany, University of the bacteria and fungi as they are easily available and do Madras, Chennai. not require the maintenance of highly aseptic conditions.11 Among the noble metal nanoparticles, silver nanoparticles Collection of plant materials (AgNPs) are considered to be of great importance because of The healthy leaves of C. roxburghii were collected in and their high antiviral,12 antibacterial, and antifungal properties13 around Guindy campus, University of Madras, Chennai, dur- and good electrical conductivity, chemical stability, and ing January 2012. They were washed twice with tap water catalytic activity. and then rinsed with distilled water, removing dust particles Though there is a widespread use of AgNPs in the from their surface. Then the leaves were shade dried for medical, cosmetics, and pharmaceutical industries, there is 3 days at room temperature. a threat, as to the release of nanoparticles into the environ- ment and their interaction with the biotic components of the Preparation of the plant extract ecosystem.14 Different sizes and shapes of the nanoparticles The air-dried leaves were ground to coarse powder using a could pose a threat to human and environmental health.15 blender; 4.0 g of the dried leaf powder sample was taken and Hence, proper knowledge of the engineered nanomateri- mixed with 100 mL of glass distilled water. This mixture was als, their mode of interaction, uptake, accumulation, and kept at 55°C for 15 minutes in a water bath and cooled to impact on the biosystems at various levels is inevitable to room temperature and filtered through Whatman No 1 filter implement proper control to avoid nanopollution turning paper. This aqueous extract was refrigerated and used for out to be a serious ecological concern.16,17 Recently, it has further experiments. been shown that different sizes of AgNPs (20–80 nm) were toxic to thale cress (Arabidopsis thaliana) seedlings and Synthesis of AgNPs they caused stunted growth even at very low concentration. A total of 1 mL of the C. roxburghii leaf aqueous extract Hence, it is assumed that the toxicity induced by the AgNPs was added to 9 mL of 1 mM solution of silver nitrate in on the plant system might be due to the presence of the toxic a 15 mL test tube. The reaction was performed in dark at compounds present on the surface of the nanoparticles.18,19 room temperature overnight to minimize photoactivation Cassia roxburghii DC. is a graceful tree with spreading, of silver nitrate. The aqueous leaf extracts of C. roxburghii drooping branches appearing to be overweighted by its and AgNO3 solution were used as control. After the desired wealth of clustering orange–red blossoms. C. roxburghii is reaction period, the solution containing the AgNPs was native to Sri Lanka and Southern India. Cassia species are centrifuged at 15,000 rpm for 10 minutes. The pellet was widely used in folk medicine for their laxative, purgative collected and redispersed in glass-distilled water, removing uses, and for treating skin diseases, such as ring worm, any interactive biological molecules. This was repeated thrice scabies, eczema, and wounds. C. roxburghii had been to ensure better separation of the AgNPs and was used