Materials Letters 206 (2017) 217–220
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Microwave assisted green synthesis of MgO nanorods and their antibacterial and anti-breast cancer activities K. Karthik a, S. Dhanuskodi a,⇑, S. Prabu Kumar b, C. Gobinath c, S. Sivaramakrishnan b a
School of Physics, Bharathidasan University, Tiruchirappalli 620 024, India Department of Biotechnology and Genetic Engineering, Bharathidasan University, Tiruchirappalli 620 024, India c Academic Body of Agriculture and Food Biotechnology, Universidad Autonoma del Estado de Hidalgo Tulancingo, Hidalgo CP 43600, Mexico b
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Article history: Received 26 November 2016 Received in revised form 24 May 2017 Accepted 1 July 2017 Available online 3 July 2017 Keywords: MgO Microwave assisted green synthesis Foodborne pathogens Breast cancer cell line
a b s t r a c t MgO has been synthesized using Andrographis paniculata (A. paniculata) which crystallizes in the cubic structure with the average crystallite size of 35 nm. SEM reveals the formation nanorods (diameter: 46 nm, length: 185 nm). From the luminescence spectrum, oxygen defects (467 nm) were observed. It shows good antibacterial activity with a zone of inhibition of 19 mm (V. cholerae) and 29 mm (S. flexneri) against aquatic and foodborne pathogens. It also exhibits anti-breast cancer (human breast adenocarcinoma MCF-7: IC50:15.76 mg/mL) activity along with biocompatibility. Ó 2017 Elsevier B.V. All rights reserved.
1. Introduction Metal oxide nanoparticles (NPs) have been extensively utilized in a broad range of bio applications like drug and gene delivery, cell and tissue engineering, diagnostics and therapeutic purposes etc. Among these applications, evaluation of the antibacterial and anticancer activities can lead to an inexpensive treatment and an easy medication with minimal side effects [1,2]. A considerable economic loss in fishery farming is due to the diseases caused by a variety of opportunistic aquatic pathogens like Vibrio cholerae, Streptococcus aureus, Aeromonas hydrophila and Pseudomonas aeruginosa. Also foodborne illness causes major health problems in both developing and developed countries. Centres for Diseases Control and prevention (CDC, USA) have now declared E. coli, S. flexneri, S. aureus and S. typhi as major foodborne pathogens. Also the most commonly diagnosed cancers world-wide are lung, breast and colorectal cancers. Among these, breast cancer continued to be the most frequently occurring cancer in women around the world. Though there are several treatment approaches like chemotherapy, radiotherapy etc., there is no effective drug for most of the cancers and those practiced have some serious ill effects that damage the healthy tissues [3]. Hence, in order to limit the bacterial growth and to replace the existing drugs, researchers are in search of new biocompatible drugs with enhanced antibacterial and anticancer activities [4]. ⇑ Corresponding author. E-mail address:
[email protected] (S. Dhanuskodi). http://dx.doi.org/10.1016/j.matlet.2017.07.004 0167-577X/Ó 2017 Elsevier B.V. All rights reserved.
MgO is one of the most important functional metal oxides which has been widely used in various fields such as catalysis, toxic waste remediation, refractory material industry, paints and superconductors [5,6]. MgO has attracted significant interest in biomedical applications due to its non-toxic nature [7,8]. Microwave assisted green synthesis is one of the most sensitive methods which is advantageous over the physical and chemical methods as it is simple, inexpensive and eco-friendly. Recently, Umaralikhan et al. have reported the fabrication of MgO NPs using the leaf extract P. guvajava and A. Vera for the antibacterial activity against S. aureus and E. coli [9]. Jeevanandam et al. have synthesized MgO NPs from plant extracts via induced molecular nucleation [10]. Anticancer activities of bio engineered MgO NPs have been investigated by Sugirtha et al. on human cervical cancer (HeLa cells with IC50 value 31.2 mg/mL) [11]. Therefore, the present study is focused on using A. Paniculata leaf extract as the stabilizing agent in the synthesis of MgO nanostructures for the antibacterial (aquatic and foodborne pathogens) and anticancer (human breast cancer cell line MCF-7) applications. 2. Experimental details 2.1. Materials Dry leaves of A. paniculata were collected from the Bharathidasan University campus. The identity of the plant was confirmed by the taxonomy experts in the Department of Plant Science, Bharathidasan University.
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K. Karthik et al. / Materials Letters 206 (2017) 217–220
2.2. Preparation of the plant extract 10 g of A. paniculata leaves were washed with double distilled water and heated at 393 K for 30 min to extract the dark green dye. The extract was filtered twice to eliminate the residual solids. 2.3. Green synthesis of MgO nanorods 0.5 M of Mg(CH3COO)24H2O was homogenously mixed with 100 ml of A. paniculata extract. The solution was stirred at 303 K for 2 h until a clear solution was obtained. The plant extract was served as a fuel, while the acetate in the precursor served as the oxidizer. The clear solution was placed in a domestic microwave oven (1 kW, 2.45 GHz) and irradiated for 20 min in the convection mode. The resulting powder was calcined at 673 K for 2 h and then finely ground to get MgO nanorods. Characterization, procedures for the antibacterial, hemolytic and anticancer activities are provided in the Supporting Information. 3. Results and discussion 3.1. Structural and morphological studies Fig. 1a shows the X-ray diffraction pattern of bioengineered MgO NRs and the cell parameter is a = 0.4210 nm with face centred cubic phase (JCPDS card no: 77–2364). The average crystallite size (D = 35 nm) is calculated using Debye Scherrer’s formula [12]. The
Williamson-Hall (W-H) plot (bcosh against 4sinh) provides the information about the microstrain which is expected to be a horizontal line, parallel to the sinh axis, whereas in the presence of strain, it has a non-zero slope as given in Fig. S1. The calculated values of microstrain (e) and dislocation density (d) are 0.0018 and 7.9528 1014 lines/m2 respectively. The SEM image shows rod-like structure (diameter: 46 nm, length: 185 nm) (Fig. 1b). EDS analysis reveals the presence of Mg and O without any impurity peak (Fig. 1c). FTIR absorption bands at 3443 and 1631 cm 1 are attributed to OAH stretching and bending modes respectively. The band at 1383 cm 1 is the characteristic bending vibration of carbonyl group (CO23 ) and the band at 511 cm 1 is associated with the stretching Mg-O mode (Fig. S2) [13]. From the luminescence studies, the emission bands at 449, 467 nm are due to the oxygen defects (Supporting Information). 3.2. Antibacterial activity The antibacterial activity was tested against aquatic (P. aeruginosa and V. cholerae) and foodborne pathogens (E. coli, S. flexneri, S. aureus) for different concentrations (25–100 mg/mL) (Fig. 2a–b). Fig. 2c represents the ZOI observed for the aquatic and foodborne pathogens. Interestingly in the present study, MgO NRs have shown more prominent zone of inhibition (29 mm) against S. flexneri when compared to the standard antibiotic streptomycin. The obtained results are compared with the ZOI of selected foodborne pathogens for MgO NPs (Table 1). From the luminescence studies
Fig. 1. (a) XRD pattern (b) SEM images (c) EDS of MgO NRs.
Fig. 2. (a–b) Plate photos of V. cholerae and S. flexneri (c) ZOI of MgO NRs.
K. Karthik et al. / Materials Letters 206 (2017) 217–220 Table 1 Comparison of antibacterial and anticancer activities with some other bioengineered metal oxide NPs. Sample
Test organism/ Cancer cell line
ZOI (mm)/ IC50 (mg/mL)
Ref.
MgO: 5 mg/mL (P. guvajava) 873 K for 2 h MgO: 5 mg/mL (A. vera) 873 K for 2 h MgO: 100 mg/mL (A. paniculata) 673 K for 2 h CuO (M. oleifera) 673 K for 2 h CuO (A. indica) 673 K for 2 h MgO (A. paniculata) 673 K for 2 h
S. aureus E. coli
16 15
[9] [9]
S. aureus E. coli
15 12
[9] [9]
S. aureus E. coli
18 20
Present work Present work
MCF-7
26.71
[18]
MCF-7
25.55
[18]
MCF-7
15.76
Present work
(Fig. S3), the emission bands at 449, 467 nm are due to the oxygen vacancies leading to higher number of reactive oxygen species (ROS). The commonly accepted mechanism of the antibacterial
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activity is the production of ROS (OH ,O2 and H2O2) on the surface of the NPs when the light causes oxidative stress in bacterial cell wall, eventually leading to the death of the cells. Another possible mechanism is when Mg2+ ions are released from MgO NRs with uneven surface and rough edges as evident from the SEM images, they come into contact with the cell membrane of the microbe. The cell membrane with negative charge and Mg2+ mutually attract. Mg2+ penetrates into the cell membrane and reacts with S-H group inside the cell membrane and damage it leading to the cell death (Fig. 3a) [14–16]. 3.3. Anticancer activity The biocompatibility potential of MgO was evaluated with normal cells, especially RBC’s. Hemolytic activity of green synthesized MgO NRs was carried out with different concentrations (20 and 40 mg/mL) on RBC’s. As per the, International Organization for Standardization Technical Report 7406 is the admissible level for biomaterials
