International Journal of Biological Macromolecules 74 (2015) 179–184
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k-Carrageenan/poly vinyl pyrollidone/polyethylene glycol/silver nanoparticles film for biomedical application Moustafa M.G. Fouda a,d,∗ , M.R. El-Aassar b,∗∗ , G.F. El Fawal b , Elsayed E. Hafez c , Saad Hamdy Daif Masry c , Ahmed Abdel-Megeed e,f a
Petrochemical Research Chair, Chemistry Department, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia Polymer Materials Research Department, Institute of Advanced Technology and New Material, City of Scientific Research and Technology Applications, New Borg El-Arab City, 21934 Alexandria, Egypt c Plant Protection and Biomolecular Diagnosis Department, Arid Lands Cultivation Research Institute, City of Scientific Research and Technology Applications, New Borg El-Arab City, 21934 Alexandria, Egypt d Textile Research Division, National Research Center, Dokki, PO Box 12622, Giza 12522, Egypt e Plant Protection Department, Faculty of Agriculture, (Saba Basha), Alexandria University, Alexandria, Egypt f Botany and Microbiology Department, College of Science, King Saud University, P.O. Box 2455-Riyadh 11451, Saudi Arabia b
a r t i c l e
i n f o
Article history: Received 11 October 2014 Received in revised form 13 November 2014 Accepted 21 November 2014 Available online 9 December 2014 Keywords: k-Carrageenan Poly vinyl pyrollidone Polyethylene glycol Silver nanoparticles Fungal activity
a b s t r a c t Biopolymer composite film containing k-carrageenan (KC), polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG) was formulated by dissolving KC and PVP in water containing PEG. Silver nanoparticles (AgNPs), was produced by Honeybee and added to solution. Finally, all solutions were poured onto dishes and dried overnight at 40 ◦ C to form the final films. Tensile strength (TS) and elongation (E %) is evaluated. The water contact angle is inspected. Thermal properties (TGA) and swelling behavior for water were considered. Fungal activity is also examined. Morphology of all films was also explored using scanning electron microscope. AgNPs induced significant hydrophilicity to KC-PVP-PEG film with contact angle of 41.6 and 34.7 for KC-PVP-PEG-AgNPs. Films with AgNPs exhibited higher thermal stability and strength properties than other films without. Films with AgNPs explore lower swelling behavior than other films without. Both SEM and EDX proved the deposition of AgNPs on the surface of films. Films with AgNPs showed higher activity against pathogenic fungi compared with the chemical fungicide; fluconazole. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Over the former several years, numerous biopolymers have expected increased responsiveness for their applications in chemical, medical as well as food manufacturing [1–5]. k-Carrageenan is considered as biopolymer, water-soluble, which is sulfated galactan, obtained from red algae. It is contained of repeating units of disaccharide; 3-linked -d-galactose 4 sulfate and 4-linked 3, 6-anhydro ␣-d-galactose. They are involved in huge number of
∗ Corresponding author at: Petrochemical Research Chair, Chemistry Department, College of Science, King Saud University, P.O. 2455, Riyadh 11451, Saudi Arabia. Tel.: +966 560773127. ∗∗ Corresponding author at: Polymer Materials Research Department, Institute of Advanced Technology and New Material, City of Scientific Research and Technology Applications, New Borg El-Arab City, 21934, Alexandria, Egypt. Tel.: +2012 00550669; fax: +203 4593414. E-mail addresses: m
[email protected],
[email protected] (M.M.G. Fouda), mohamed
[email protected] (M.R. El-Aassar). http://dx.doi.org/10.1016/j.ijbiomac.2014.11.040 0141-8130/© 2014 Elsevier B.V. All rights reserved.
applications such as nutrients, microencapsulation, therapeutic, industries as gelling and stabilizing agents. k-, l-, and i-carrageenan are named isomers of carrageenan, and depending on the position of each ester sulfate group in the chemical configuration structures, as well as the repeating units, they are classified [6]. k-Carrageenan solution could form a strong thermally reversible gel while cooling in presence of potassium [7]. During cooling process, and/or through ionic interactions, k-carrageenan transform from a coil state to helix structure, [8]. k-Carrageenan partakes only one negative charge for each disaccharide unit with an affinity to form a strong and rigid gel. Polyethylene glycol is safe polymer, with no odor, has oily properties, nonvolatile and is mainly utilized in a diversity of medical purposes as solvent, dispensing agent, cream manufacturing and suppository bases as well [9]. PEG is also identified as polyethylene oxide (PEO) or polyoxyethylene (POE), based on its molecular weight, and under the trade name Carbowax. PEG is water-soluble polymer, and also can soluble in solvents as methanol, benzene, and dichloromethane and is insoluble in diethyl ether and hexane. PEG
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is exploited to prepare different types of hydrogel. The mixtures of polyvinyl alcohol (PVA) and (PEG) in presence of calcium chloride (CaCl2) were exposed to gamma-irradiation in order to produce transparent and prospective hydrogels in applications for wound dressing [10]. Synthetic polymer supplies [11–14] such as PVP could work on strengthen the fibrous backbone and exhibited greater capacity to support the formulated films of natural polymers. PVP is one of limited environmental synthetic polymers used widely in food industry, medical and private care stuffs. Several works or review papers have been published about the synthesis of silver nanoparticles using natural and synthetic polymers [15–20]. In this work, biosynthesized of AgNPs will be approached using the honeybee extract, which contains many compounds. It is well known that honeybee body contains both of exocrine and endocrine glands. These glands produce a number of active compounds, some are poisons and others are beneficial. By adding silver nitrate to honey bee fluids, AgNPs are produced and be covered by one or more active compounds coming from honeybee glands that kill the pathogen fungi in addition to the toxicity of the AgNPs itself.
nanosilver (AgNPs), was added to the formulated film solution. Finally, samples were poured onto polystyrene Petri dishes and dried overnight at 40 ◦ C to form the corresponding films. To this end, all prepared films were stored in desiccators until using. 2.5. Characterization of the obtained films 2.5.1. Swelling studies Swelling studies were carried out in water, on all the prepared films at room temperature. All prepared samples were dipped in Petri dishes filled with 30 ml of distilled water. At different intervals, films were moved out, and the water was wiped from the surface of all films using filter paper, then all films are weigh up. Fresh water was used again for further swelling study. The swelling percentage of all obtained films is then calculated:
swelling percentage (%) =
Wt − W0 W0
× 100
where Wt is the weight of swollen films at time t and W0 is the initial weight of samples [21]. Tests were carried out in triplicate and all results were reported in term of mean value.
2. Materials and methods 2.1. Materials Kappa-carrageenan (KC), polyvinylpyrolidone (PVP), PEG (12,000 Mw/g/mol), and all the chemicals were purchased from Sigma-Aldrich. Distilled water was also utilized in film preparation. All other chemicals and reagent were used without any further purification. 2.2. Microorganisms Asprgillus sp. (KJ831193), Pencillin sp. (KJ831195) and Fusarium oxysporum (HQ438698) were selected as pathogenic test organism in this work and were obtained from the Plant protection and Biomolecular Diagnosis Department, Arid Lands Cultivation Research Institute, City of Scinintific Research and Technology Applications, Alexandria, Egypt. 2.3. Synthesis of silver nanoparticles using honeybee Honeybee workers (Aves amylofera) were collected from honeybee colony (MuCSAT Farm), Arid Lands Cultivation Research Institute Farm. About 100 honeybees’ workers were ground in liquid nitrogen using mortar and pestle. The honeybee powder was added to 100 ml of sterile Phosphate Saline Buffer (PBS) and mixed very well. A 0.1 g of silver nitrate was added to the mixture. The mixture was incubated in dark room at room temperature with contentious shaking (200 rpm). The OD of the mixture was monitored using spectrophotometer at 480 nm. The mixture was subjected to centrifugation (10,000 rpm for 15 min) after the OD stops increasing. The pellet (nanoparticles) was obtained and washed three times with distilled sterile water. The Silver nanoparticles (AgNPs) was dried at 50 ◦ C for 1 h and then subjected to characterization. 2.4. Film preparation The film formulation was carried out according to the following steps: 1 g of k-carrageenan; (KC 70% w/w) and polyvinylpyrolidone; (PVP, 30% w/w) were dissolving in 100 ml distilled water containing 25% of glycerol (Gly) depending on the weight ratio of carrageenanpolyvinylpyrolidone (KP) and 0.4% of polyethylene glycol (12,000); at 70 ◦ C. The solution mixture is left under strong mixing in a helix mixer for 30 min. afterwards, pre-determined amounts of
2.5.2. Tensile strength and elongation measurements Tensile strength (TS) as well as elongation at break percentage (E %) of all obtained films were calculated and evaluated using Shidmadzu universal testing machine (model AG-I 5 KN, Shidmadzu, Japan). Initial grip separation was set at 5 cm, and cross-head speed was set at 30 mm/min. TS was calculated by dividing maximum load (force) by initial cross-sectional area of a specimen. Elongation at break; E was expressed as percentage of change of initial gauge length of a specimen (5 cm) at the point of sample failure. The thicknesses of all prepared films were determined using an electronic digital micrometer (Mitutoyo, Japan) that has a sensitivity of 0.001 mm and all the measurements were carried out, at least from five random positions on each film. Then, the mean value was used for the calculations of mechanical properties. 2.5.3. Contact angle analysis The contact angle represents the inside angle between the surface of the KC-PVP-PEG film and the tangent to the surface of the water [22]. The hydrophobicity or wettability of all obtained film surfaces was calculated by measuring the contact angle that carried out with water using a goniometer (Ramé—hart, model 500-F1, France). To accomplish the measurements, a syringe was filled with 5 ml of water, and a drop was placed on top of the film surface that was glued on a well-leveled smooth platform. The angle between the baseline of the drop and the tangent at the drop boundary was calculated. The test was repeated 10 times at 10 different, random locations for each sample and the average contact angle value was reported. 2.5.4. Characterization of the films The morphology of the composite films with and without silver nanoparticles was analyzed using scanning electron microscope, obtained with (JEOL GSM-6610LV, Japan) at an accelerated voltage of 15 kV. The surfaces were vacuum coated with gold for SEM. X-ray diffraction (XRD) pattern of dry nanoparticle powder was obtained using X-ray power diffraction (Shimadzu XRD 7000 X-ray diffractometer, Japan). Thermal degradation behaviors of all formulated films were studied and evaluated by using Thermo Gravimetric Analyzer (Shimadzu Thermal Gravimetric Analysis (TGA)—50, Japan); instrument using a temperature range from 20 ◦ C to 800 ◦ C under nitrogen atmosphere, flow rate of 20 ml/min and at a heating rate of 10 ◦ C/min. The chemical structure of the obtained films was also analyzed by Fourier transform infrared spectroscopy (FT-IR)
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Fig. 1. Swelling ability of KC-PVP-PEG pure Film; and KC-PVP-PEG-Ag NPS film.
spectra using FT-IR spectrometer (Shimadzu FTIR-8400 S, Japan), connected to a PC, and analysis the data by IR Solution software, Version 1.21.
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Fig. 2. Stress × strain curves of KC-PVP-PEG film and KC-PVP-PEG-AgNPs composites film.
3.3. Contact angle
2.5.5. Fungal isolates and fungicides Three different pathogenic fungi; F. oxysporum, Pencillium sp. and Sprgillus sp.; were grown up on peptone dextrose medium (5 liquid medium), each fungi were treated once by fluconazole (Chemical fungicide, Sigma Aldrich, USA) and the biosynthesized nanosilver as well as the biofilms was used as bio-fungicide. The growth inhibition zone was recorded in term of turbidity on a spectrophotometer at 540 nm.
The main objective of this study was to change the properties of films by addition of cross-linker compound; therefore, the superficial hydrophilicity of films was calculated by the contact angle method. In general, higher angles signify less hydrophilic surface. The contact angles of KC-PVP-PEG composite film was 41.6◦ , while the angle for KC-PVP-PEG-AgNPs film was 34.7◦ . This result indicate the influence of Ag on the hydrophilicity of the prepared films. These data exhibited that KC-PVP-PEG film has a relatively higher contact angle (less hydrophilic) than for KC-PVP-PEG-AgNPs films. This due to the rougher surface caused by the presence of AgNPs loaded onto the film.
3. Results and discussion
3.4. Microstructure
3.1. Swelling studies
The surface microstructures depended on the drying conditions (evaporation rate of the solution) and especially depend on the humidity during drying [26]. All images; Fig. 3 show the SEM of both KC-PVP-PEG and KC-PVP-PEG-AgNPs composite film at different magnification power. It is obviously clear that, AgNPs is deposited on the surface of KC-PVP-PEG composite film, as described in Fig. 3B and these particles has been aggregated into insular formations. This can be attributed to; some silver nanoparticles are coated by polysaccharides and proteins, hence, a physical barrier prevent diffusion of silver through the polymer solutions and small part of silver was formed onto the surface of the film. SEM images of composite film with AgNPs prepared by honeybee as well as EDX analysis are shown in Fig. 4. As described in Fig. 4A, AgNPs obtained with raw honeybee are clearly visible as spherical particles shapes throughout the surface of the honeybee powder. Energy-dispersive X-ray analysis (EDX) was used to analyze the elemental constitution of solid samples. Elementary analysis of AgNPs prepared by honeybee was carried out by using SEM-EDX software also appears in the same Figure. The results show that carbon, oxygen, and Ag were the principal elements of AgNPs prepared by honeybee. The EDX quantitative analysis confirms the nanostructure that contains about 19.85 wt% Ag, 45.22 wt% carbon, and about 34.93 wt% oxygen, The EDX analysis thus, provides direct evidence that Ag particles are embedded into the honey bee. It is indicated that silver nanoparticles were well prepared without any chemical and structural modifications into the honeybee. As described clearly in Fig. 5, the crystalline nature of AgNPs obtained by honeybee was confirmed as elemental Ag0 using XRD and the calculation revealed that the size of the bionanparticles ranged from 20 to 60 nm. The diffraction peaks appearing at 32.3◦ ,
The term swelling from the polymer science point of view is the increase of volume for a specific polymer due to the absorption of a solvent. In our case, the solvent here is water and the polymers subjecting to the presented study are KC-PVP-PEG and KC-PVP-PEG-AgNPs as well. Results of swelling percentages (%) are illustrated in Fig. 1. The swelling ratio increases with time. It is well recognized that, swelling is encouraged by the electrostatic repulsion of ionic charges existing within the polymer network. The reduction in the absorption capacity could be attributed to the decrease in pore amounts due to the incorporation of silver nanoparticles and to the plasticizer part observed for PVP-PEG containing samples, which leads to a reduction in swelling performance. In addition, the hydrophilic nature of the corresponding films is enriched by increasing the amount of KC.
3.2. Mechanical properties The formulated polymer solution of KC-PVP-PEG produces flexible, transparent and uniform films due to viscoelastic nature of KC [23–25]. The stress–strain measurements of KC-PVP-PEG films prepared with and without AgNPs were shown in Fig. 2. KC-PVP-PEG film exhibited higher strength with higher percentage of elongation whereas, the opposite mechanical behavior was noticed for KCPVP-PEG-AgNPs films which showed lower tensile strength with lower elongation % compared with KC-PVP-PEG films. This can be explained in term of the negative effect of AgNPs on the polymeric network structure as well as the polymeric network performance of the formed film.
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Fig. 3. SEM surface (A–B) and cross-section (A –B ) images of KC-PVP-PEG film, and KC-PVP-PEG-AgNPS.
Fig. 6. TGA analysis for KC-PVP-PEG and KC-PVP-PEG-AgNPs.
Fig. 4. SEM image of (A) eco-friendly syntheses of silver nanoparticles (AgNPs), (B) silver elemental distribution, and Stoichiometric ratio of AgNPs/honeybee by EDS.
Fig. 5. XRD spectra of dried powder of silver nanoparticles.
46.6◦ , and 76.8◦ correspond to the (1 1 1), (2 0 0), and (3 1 1) of the face centered cubic crystal structure, respectively [27]. This suggests that the silver nanoparticles (AgNPs) were prepared using honey. This result was in accordance with the EDX result analysis. In addition, their intensities are remarkably enhanced with increasing AgNO3 content in the honeybee. The thermal stability of the KC-PVP-PEG and KC-PVP-PEGAgNPS composite films was also analyzed by using thermogravimetric analysis under N2 atmosphere as described in Fig. 6. The temperature range was from room temperature to 800 ◦ C at a heating rate of 10 ◦ C/min. The result shown in Fig. 6 exploits that, the stability of KC-PVP-PEG-AgNPs composite film was higher than KC-PVP-PEG without silver particles. This can be explained clearly by the decomposition rate of both KC-PVP-PEG and KC-PVPPEG-AgNPs composite films. With respect to KC-PVP-PEG film, at 240–400 C, the weight loss/decomposition was 1.6 mg while at the same temperature, KC-PVP-PEG-AgNPs composite; the weight loss was 0.620 mg. By comparing the two decomposition values, we can conclude/explain that, this difference is due to the higher stability
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Table 2 The percentage of growth inhibition obtained by the biosynthesized nanosliver against Penicillium sp. Concentrations (g/ml) 0 10 20 30 40 50 60 70 80
Fig. 7. FTIR spectrum of KC-PVP-PEG and KC-PVP-PEG-Ag NPS.
of KC-PVP-PEG-AgNPs composite compared with the KC-PVP-PEG film. In addition to the residual percentage of KC-PVP-PEG-AgNPs was higher than KC-PVP-PEG film, which confirms the formation of KC-PVP-PEG-AgNPs composite matrix. Fig. 7 shows the FT-IR spectra of both KC-PVP-PEG and KC-PVPPEG-AgNPs composite films attained in the wave numbers range 400–4000 cm−1 . It is observably cleared that the most characteristic bands are 3498 cm−1 confirming the presence of OH stretching vibration in KC-PVP-PEG and KC-PVP-PEG-AgNPS film. Also, a band at 1650 cm−1 corresponding to C H stretching of methyl or methylene group of KC-PVP-PEG.
Inhibition (%) Fluconazole
AgNPs
0 23.34 22.11 24.67 49.84 53.01 53.24 59.22 62.31
0 31.28 31.43 49.16 48.56 51.32 57.44 56.06 56.13
Table 3 The percentage of growth inhibition obtained by the biosynthesized nanosliver against Aspergillus niger. Concentrations (g/ml) 0 10 20 30 40 50 60 70 80
Inhibition (%) Fluconazole
AgNPs
0 39.53 50.54 61.42 66.27 82.61 80.45 82.50 87.29
0 32.04 62.54 70.23 75.91 77.98 78.79 77.27 85.79
5. Conclusion 4. Fungicides examination The data presented in Table 1 shows the fungicidal activity of the biosynthesized AgNPs against the plant pathogenic fungi Fusarium sp. The fungal growth was inhibited with percentage ranged from 30 to 48.4%. On the other hand, the percentage of the growth inhibition caused by the chemical fungicide fluconazole was ranged from 55 to 71.5%. Additionally, the MIC of the AgNPs was 278 g/ml but it was 104 in case of fluconazole. Table 2 shows the fungicide activity of AgNPs against Pencillium sp., the inhibition % was observed from 31 to 56%, however, this percentage was ranged from 22 to 59 in case of fluconazole. Moreover, the MIC was 138 g/ml in case of AgNPs but it was 122 g/ml, for fluconazole. The fungicide activity of AgNPs was also examined against A. Niger and data presented in Table 3 revealed that AgNPs succeeded to inhibit the fungal growth with percentage ranged between 32 and 86. Nevertheless, this percentage was ranged from 39.5 to 87 in case of fluconazole. Moreover, it was observed that the MIC was 81 g/ml in case of AgNPs but it was 83 g/ml with fluconazole.
Table 1 The percentage of growth inhibition obtained by the biosynthesized nanosliver against Fusarium sp. Concentrations (g/ml) 0 10 20 30 40 50 60 70 80
Growth inhibition (%)
In this research work, two types of composite films were successfully prepared. The first one was composed of k-carrageenan (KC), polyvinyl pyrrolidone (PVP), and polyethylene glycol (PEG). The 2nd one was composed of (KC), (PVP), (PEG) and trapped with biosynthesized silver nanoparticles; AgNPs. Honeybee successfully produced AgNPs. The mechanical properties, the swelling behavior, the contact angle, the thermal decomposition, the morphology of the obtained films as well as the AgNPs EDX-analysis were investigated. The fungicidal activity of both AgNPs alone and the composite films with AgNPs is evaluated against different species of pathogenic fungi. The results displayed that AgNPs induced significant hydrophilicity to KC-PVP-PEG composite film with contact angle of 34.7. The TGA-results also showed higher stability for the film with AgNPs and higher strength properties than other films without. In addition, low swelling property was noticed with composite films having AgNPs. The advanced microstructure analysis proved also the in situ deposition of AgNPs onto the surface of KC-PVP-PEG film. AgNPs alone and KC-PVP-PEG-AgNPs composite film shows higher fungal activity against Asprgillus sp., Pencillin sp. and F. oxysporum compared with the chemical fungicide; fluconazole. From all these aforementioned results, it is concluded that, this composite film with AgNPs can be utilized in biomedical applications. Acknowledgement
Fluconazole
AgNPs
0 55.14 59.15 60.06 68.55 60.94 71.57 70.56 79.00
0 33.64 30.27 34.60 33.88 35.31 39.04 49.33 48.38
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