Effect of Nano Particles on Antibacterial Activity of Aloe Vera

In this work, synthesis of CdS nanoparticles with Aloe vera (L. ) extract and its activity on bacterial pathogens was investigated. CdS nanoparticles were synthesized by using chemical methods. Physical properties like: X-ray diffraction (XRD), Atomic force microscopy (AFM) and UV-VIS transmission spectroscopy were employed to characterize the crystalline structure, size and transmission spectra of nanoparticles. X-ray diffraction analysis confirms the formation of cubical and hexagonal structures of CdS nanoparticle. The AFM show the formation of aggregate of nanoparticle with particle size ranging 7 – 20 (nm). The antibacterial activity of Aloe vera -conjugated CdS nanoparticles showed effective inhibitory activity against the pathogens.


INTRODUCTION
ith the development of nanotechnology since 1974, controllable synthesis of nanoparticles has attracted much attention due to their potential applications in many areas [1]. Especially, they have been extensively exploited for use in biomedical areas, such as targeted drug delivery [2], imaging [3], sensing [4] and antimicrobial [5]. Among these nanoparticles, CdS NPs are particular interest due to its strong and wide-spectrum antimicrobial activities [6][7][8][9], which might act as a novel bactericide to solve the serious antibiotic resistance problem.
CdS NPs can be successfully synthesized by traditionally chemical and physical methods. However, these methods strongly depend on severe reaction conditions, for example, aggressive agents, harmful solvent system to environment and ecology, higher temperature and higher pressure, and so on.
Aloe vera (L.) Burm.f. (Aloe barbadensis Miller) is perennial succulent xerophytes, which develops water storage tissue in the leaves to survive in dry areas of low or erratic rainfall. The innermost part of the leaf is a clear, soft, moist and slippery tissue that consists of large thin-walled parenchyma cells in which water is held in the form of viscous mucilage [1]. Aloe vera has been used for many centuries for its curative and therapeutic properties and although over 75 active ingredients from the inner gel have been identified, therapeutic effects have not been correlated well with each individual component [2]. Many of the medicinal effects of Aloe leaf extracts have been attributed to the polysaccharides found in the inner leaf parenchymatous tissue [3,4], but it is believed that these biological activities should be assigned to a synergistic action of the compounds contained therein rather than a single chemical substance [5]. Aloe vera is the most commercialized Aloe species and processing of the leaf pulp has become a large worldwide industry. In the food industry, it has been used as a source of functional foods and as an ingredient in other food products, for the production of gel-containing health drinks and beverages. In the cosmetic and toiletry industry, it has been used as base material for the production of creams, lotions, soaps, shampoos, facial cleansers and other products. In the pharmaceutical industry, it has been used for the manufacture of topical products such as intents and gel preparations, as well as in the production of tablets and capsules [6,7], important pharmaceutical properties that have recently been discovered for both the Aloe vera gel and whole leaf extract include the ability to improve the bioavailability of coadministered vitamins in human subjects [8]. In this study, the antibacterial effect of CdS / Aloe vera was evaluated against three pathogenic bacteria, including Pseudomonas aeruginosa, Proteus vulgaris and Salmonella typhi was investigated.

EXPERIMENTAL WORK • Preparation of CdS nanoparticles
CdS nanoparticles were synthesized via chemical method, using cadmium nitrate Cd(NO 3 ) 2 .4H 2 O and thioacetamide (TA); they prepared in chemical lab. , other details of preparation method were described in Ref. [10]. The structure characterization of CdS nanoparticles were performed by X-ray diffract meter (Philips, PW/1710), with monochromatised CuKα radiation of wavelength 0.15418nm at 40KV and 30mA. A UV-VIS transmission spectrum was recorded employing a Cecile-7200 double beam UV/VIS spectrophotometer supplied by Aquarius Company for the wavelength range of 200-900 nm. The surface morphology and particle size were characterized using Atomic force microscopy (Advance angstrom Inc. SPM AA3000).

• Preparation of extract
Aloe vera extract was prepared from Aloe vera leaf gel with slight modifications of the procedure by Grieve [11]. Mature, healthy and fresh leaves of Aloe vera having a length of approximately 25 to 50 cm were washed with fresh water. The leaves were cut transversely into pieces. The thick epidermis was selectively removed. The solid gel in the center of the leaf was homogenized. The crude extracts were prepared freshly each time and administered orally . The dosing schedule used was once daily.

• Antibacterial assay
Three bacterial strains were used: Pseudomonas aeruginosa, Proteus vulgaris, Salmonella typhi .The bacterial suspension was prepared and adjusted by comparison against 0.5 Mc-Farland turbidity standard (5x 10 7 cell ml -1 ) tubes. It was further diluted to obtain a final of 1.4 x 10 8 cell ml -1 . All bacteria strains were sub-culture on nutrient broth (8). The broth was inoculated by the 0.2 ml/10ml broth either with all bacteria strains, then added 1 ml of (2, 4, and 5 mg) Aloe vera and then added 1 ml of (2, 4, and 5 mg) Aloe vera & nano and other then added 1 ml of (2, 4, and 5 mg) Nano. The tubes were incubated at 37 C 0 for 24 h. The growth of control bacterial growth due to Aloe vera, Aloe vera & nano and nano was measured by turbidity at 600 nm wavelength. The mean values of inhibition were calculated from triple reading in each test. The minimum bactericidal concentration (MBC) of Aloe vera, Aloe vera & nano and nano was determined by the ten-fold dilution method against bacterial strains in vitro.
• Statistical data analysis: Data were statistically analyzed using SPSS statistical software (version 11.5). The values are given as mean ± standard error. corresponding to the hexagonal phase in the XRD spectrum [12]. Therefore, as-prepared sample is mixtures of cubical and hexagonal phases. Figure (2) explain the transmission spectrum on CdS nanoparticles., from figure can notice that transmission (T%) reach to 2.5 at short wavelength and this attribute to high absorption of nanoparticles at these wavelength, then the transmission increased as s wavelength increased [13]. The energy gaps E g of CdS nanoparticles is 2.85 eV was estimated using Tauc relation [14]. Figure (3) shows the AFM images of CdS nanoparticles, the histogram of size distribution of CdS nanoparticlesFigure (3 b) shows particle size ranging from 7-20 nm.

Figure (3) AFM image of CdS nanoparticles; a) two dimensional image. b) Histogram of crystal size distribution.
This study confirms the antibacterial effect of Aloe vera extract on various Gramnegative and Gram-positive bacteria. In particular, crude of Aloe vera is a very potent inhibitor of growth of bacteria such as clinical isolates of Pseudomonas aeruginosa, Proteus vulgaris, and Sallmonellia typhi. All bacterial pathogens failed to grow in lower and higher concentrations of Aloe vera extract, Aloe vera nano and nano ( Table  1, 2 and 3).

CONCLUSIONS
CdS Nano particle was synthesized using chemical method extract of Aloe vera leaf. The CdS NPs were characterized by XRD, UV-Visible and AFM measurements. The results suggested that Aloe vera plays an important role in the reduction and stabilization of nanoparticles. Study also found that the CdS NPs / Aloe vera shows antibacterial activity on both Gram positive and Gram negative bacteria and should be explored further for antimicrobial applications.