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Disperse dyeing and antibacterial properties of nylon and wool fibers using two novel nanosized copper(II) complexes bearing phosphoramide ligands
⁎Corresponding author. Tel.: +98 2164542766; fax: +98 2164542762. shariati@aut.ac.ir (Zahra Shariatinia)
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Received: ,
Accepted: ,
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.
Peer review under responsibility of King Saud University.
Abstract
Disperse dyeing of nylon and wool fibers with two new nanosized copper(II) complexes including phosphoric triamide ligands with formula Cu(NO3)2L2 (1) and Cu(CH3COO)2L2 (2) where L = 4-NO2C6H4NHP(O)(NC4H8O)2 (A) was performed successfully. Both complexes 1 and 2 produced yellow and green colored nylon and wool fabrics, respectively. The complexes were synthesized by ultrasonic method and characterized by 1H, 13C, 31P NMR, Fourier-transform infrared, photoluminescence, ultraviolet–visible spectroscopy, X-ray diffraction, field-emission microscopy and elemental analysis. The FE-SEM micrographs revealed that the nanoparticles of these compounds are spherical in morphology and ∼17–20 nm in size. Very appropriate washfastness while poor lightfastness results were deduced for the dyed fibers. The in vitro antibacterial activities of the dyes 1, 2 and dyed wool/nylon fibers against the Gram-positive Bacillus subtilis bacterium illustrated increasing in the antibacterial effect by increasing the dye concentration from 0.1% to 0.5% o.w.f. on both wool and nylon dyed fibers.
Keywords
Copper(II) complex
Disperse dyeing
Nanoparticle
Antibacterial activity
Wool and nylon fibers
Phosphoric triamide
1 Introduction
Currently, the phosphoramide derivatives have found a number of significant applications such as anticancer (Tobias and Borch, 2001), antibacterial (Vassiliou et al., 2008) and antiviral agents (Mehellou et al., 2007; McGuigan et al., 2009). In addition, these compounds are well-known inhibitors of various enzymes such as urease and acetylcholinesterase enzymes (Gholivand et al., 2006a; Stivers and Nagarajan, 2006). Up to now, numerous complexes have been synthesized using phosphoramide ligands (Murugavel and Singh, 2006; Gubina et al., 2002, 2009; Moroz et al., 2009). Nevertheless, to the best of our knowledge, the application of these complexes as dyes for coloring fibers has not been reported yet.
Recently, there has been a great interest to find new health and hygiene related textiles for the human well being (Farouk and Gaffer, 2013; Ghoranneviss et al., 2011; Shahid et al., 2012). Since textiles have several applications in life including conventional clothing usage, masks, hospital covers and surgical gowns, there is a growing demand to develop materials to enhance protection against microbes such as bacteria, moud or fungi. The textile fabrics are prone to bacterial growth owing to their large surface areas and ability to maintain moisture, thus they can act as carriers and ideal places for the growth of microorganisms such as pathogenic or odor-generating bacteria and molds especially when they are in contact with the human body (Gupta et al., 2004). Consequently, it is imperative to develop textiles that are resistant to microbes. Disperse dyes are colored compounds with relatively small molecular weights having low water solubilities and are suitable for dyeing hydrophobic fibers such as cellulose acetate, nylon, polyester, polypropylene and acrylic fibers from an aqueous dispersion (Rabiei et al., 2012; Long et al., 2012; Burkinshaw and Jeong, 2012; Ujhelyiova, 2007). Literature review indicates that there are few reports on the synthesis and dyeing applications of inorganic complexes (Koprivanac et al., 1993; Yuzhen and Dongzhi, 1995; Grabaric et al., 1993; Blus, 1994; Kocaokutgen and Özkınalı, 2004; Koprivanac, 1997) because most of synthetic dyes reported up to now have been organic compounds (Sayed et al., 2012; Zhang et al., 2007; Blanco et al., 2009; Khosravi et al., 2006).
Because of the high strength, elasticity, and resiliency of wool that has good dye-ability and comfort, there has been an exceptional attention in creating novel ideas for wool fibers (Xu et al., 2006; Sun and Tang, 2011; Hassan and Davies-McConchie, 2012). Wool is an abundant source of structural protein generally referred to as wool keratin that is both biocompatible (Tachibana et al., 2002) and biodegradable (Rouse and Van Dyke, 2010) and consequently can be used for biomedical applications or to conjugate bioactive molecules (Kurimoto et al., 2003). The keratin from wool is extracted to create films (Yang et al., 2009), nanofibers (Ki et al., 2007), sponge (Tachibana et al., 2002) and particles (Li et al., 2009).
It has been found that nylon has several remarkable characteristics such as flexibility in surface functionalities and mechanical performance making it superior to many other forms of synthetic or/and natural polymeric materials (Pant et al., 2013). For example, nylon 6 (N6) resembles the collagen protein in its backbone structure and active groups, and has an excellent stability in human body fluids (Liu et al., 2007; Lin et al., 2006; Waugh and Lawrence, 2011). The formations of hard tissue scaffolds using N6 have been investigated (Mehrabanian and Nasr-Esfahani, 2011; Fornes et al., 2001; Wang et al., 2007). Moreover, nylon is used as medical threads, artificial skin and tissue engineering scaffolds (Li et al., 2006; Bergshoef and Vancso, 1999).
In this work, using ultrasonic method, nanoparticles of two novel copper(II) complexes bearing phosphoric triamide ligands were synthesized and characterized by multinuclear NMR, FT-IR, photoluminescence, UV–visible spectroscopy, XRD and FE-SEM microscopy. The dyeing abilities of these colorful complexes were tested quantitatively on wool and nylon fibers. It is noteworthy that to the best of our knowledge, this is the first time that transition metal complexes including phosphoramide ligands are used as dyes for dyeing fibers. Also, the antibacterial properties of the dyed wool and nylon fibers were evaluated against the Gram-positive Bacillus subtilis bacterium.
2 Experimental
2.1 Spectroscopic measurements
The 1H, 13C and 31P spectra were recorded on a Bruker Avance DRS 500 spectrometer. 1H, 13C and 31P chemical shifts were determined relative to internal Si(CH3)4 and 85% H3PO4 as external standards, respectively. Fourier-transform infrared (FT-IR) spectra were recorded on a Bruker spectrometer. Elemental analysis was performed using a Heraeus CHN-O-RAPID apparatus. Melting points were obtained with an Electrothermal instrument. The field-emission scanning electron microscopy (FE-SEM) micrographs were taken from Philips instrument (XL30), under vacuum, accelerated at 20 kV.
2.2 Dyeing fibers, wash fastness and light fastness tests
Dyeing the wool and nylon fibers was carried out using five different concentrations of each dye including 0.1%, 0.2%, 0.3%, 0.4%, 0.5% o.w.f. (on the weight of fabric). The dye was dissolved in ethanol and added to the dye bath at pH = 5.5 (adjusted with 3 mL of acetic acid). The alkyl polyglycol ether as a dispersible agent was also added to the bath and then the bath temperature was raised to about 40 °C. The wool/nylon fibers were added to the bath and the temperature was increased to 80 °C with a rate of 2 °C/min and maintained at 80 °C for 45–60 min. After that, the fibers were given 10 min rinse in running tap water and finally were dried in air.
Fastness to washing tests, according to BS 1006:C06 (1990), were carried out in the Washtec-A2 series machine. For the washfastness assessments, a rating scale of 1 (poor) to 5 (excellent) was used. Lightfastness tests were carried out for 16 h irradiation to the dyed samples according to BS 1006: B02 (1990) in a Xenotest machine equipped with a D65 lamp that has a full white light spectrum plus UV-A between 320 and 400 nm. Light fastness was assessed by comparing the change in sample color with the Blue Scale 1–8. The reflection spectra were recorded by a Color-eye 700A Cretag-Macbeth spectrophotometer for obtaining color strength (K/S) and CIELab values (L∗, a∗, b∗, c∗, h°). The K/S ratios in visible region of the spectrum (400–700) were calculated based on the Kubelka–Munk equation, K/S = (1 − R)2/2R, where K is the adsorption coefficient, R is the reflectance of each dyed sample and S is the scattering coefficient.
2.3 In vitro antibacterial activities
The in vitro antibacterial activities of the dyes 1, 2 and wool/nylon fibers dyed with five different concentrations of these dyes (0.1–0.5% o.w.f.) were evaluated by the filter paper disk method (Shariatinia and Nikfar, 2013). In these experiments, the Gram-positive Bacillus subtilis (B. subtilis) bacterium was examined. The bacteria were cultured in nutrient agar medium and used as inocula. The dyes 1 and 2 were dissolved in ethanol and the Whatmann filter paper disks (diameter 6.5 mm) were soaked into the dye solutions to adsorb the dyes. The disks were then air-dried to remove the surface solvent and placed on the surface of a sterilized agar nutrient medium that was inoculated with the test bacterium. For the dyed fibers, 0.004 g of each sample was directly placed on the agar medium. The thickness of the agar medium was kept equal in all Petri dishes. Next, the disks were incubated at 37 ± 1 °C for 24 h. The zones of inhibition growths were measured indicating the inhibitory activities of the samples on the growth of the bacterium. The average of three diameters was calculated for each assay.
2.4 Synthesis
2.4.1 Bis[N-4-nitrophenyl-N,N-bis(morpholinyl) phosphoric triamide] copper(II)nitrate (1)
To a solution of N-4-nitrophenyl-N′,N′′-bis(morpholinyl) phosphoric triamide (Shariatinia et al., 2013a) (2 mmol, 0.713 g) in methanol, copper(II) nitrate trihydrate (1 mmol, 0.242 g) was added dropwise and the reaction flask was placed in an ultrasonic bath at 30 °C for about 1 h. Then, the solution was evaporated at room temperature and the yellowish-green precipitate was filtered, washed with ethyl acetate and dried. Yield: 65%. M.p. = 173–174 °C. Anal. calcd. For C28H42N10O16P2Cu: C, 37.36; H, 4.70; N, 15.56. Found: C, 37.35; H, 4.69; N, 15.57%. 31P NMR (d6-DMSO): δ = 11.81 (m). 1H NMR (d6-DMSO): δ = 3.14 (m, 8 H, 4 CH2), 3.59 (m, 8 H, 4 CH2), 7.29 (d, 3J(H,H) = 8.1 Hz, 2 H), 8.12 (d, 3J(H,H) = 8.1 Hz, 2 H). 13C NMR (d6-DMSO): δ = 45.84 (s, CH2), 66.09 (d, 3J(P,C) = 5.4 Hz, CH2), 118.50 (d, 3J(P,Cortho) = 6.9 Hz), 126.29 (s), 142.82 (s), 149.96 (s). FT-IR (KBr): ν = 3369 (NH), 3150, 3034, 2988, 1601 (NO2), 1505, 1340 (NO2), 1257, 1204 (P⚌O), 1103 (P—N), 968 (P—N), 928, 847, 798, 734, 687, 612, 519, 472 cm−1. UV–Vis: λ(max) = 333 nm. Fluorescence (methanol): λ(max) = 360 nm.
2.4.2 Bis[N-4-nitrophenyl-N,N-bis(morpholinyl) phosphoric triamide] copper(II)acetate (2)
To a solution of N-4-nitrophenyl-N′,N′′-bis(morpholinyl) phosphoric triamide (10 mmol, 0.713 g) in methanol, copper(II) acetate monohydrate (10 mmol, 2.00 g) was added dropwise and the reaction flask was placed in an ultrasonic bath at 30 °C for about 1 h. Then, the solution was slowly evaporated at room temperature to yield the nanoparticles of the yellowish-green product. Yield: 60%. M.p. = 167–168 °C. Anal. Calc. For C32H48N8O14P2Cu: C, 42.98; H, 5.41; N, 12.53%. Found: C, 42.96; H, 5.40; N, 12.52%. 31P{1H} NMR (202.45 MHz, CDCl3): δ = 13.91 (s). 1H NMR (500.13 MHz, CDCl3): δ = 3.09 (m, 8 H, CH2), 3.54 (m, 8 H, CH2), 7.24 (d, 2H, Ar—H), 8.06 (d, 2H, Ar—H). 13CNMR (75.47 MHz, CDCl3): δ = 45.87 (s), 68.09 (s), 118.52 (d, 3J(P,C) = 6.2 Hz), 126.27 (s), 142.79 (s), 149.94 (s). FT-IR (KBr, cm−1): 3487 (NH), 3353, 3150, 3033 (CH), 2966 (CH), 2854, 2358, 1601, 1495 (NO2), 1450, 1341 (NO2), 1307, 1257, 1206 (P⚌O), 1101 (P—N), 989 (P—N), 928, 845, 797, 736, 686, 519, 489. UV–Vis: λ(max) = 350 nm. Fluorescence (methanol): λ(max) = 390.5 nm.
3 Results and discussion
3.1 Spectroscopic and microscopic study
In this study, two new colorful copper(II) complexes containing phosphoric triamide ligands were synthesized (Scheme 1) and characterized by FT-IR, multinuclear NMR, UV–Vis and fluorescence spectroscopy. A summary of the NMR and FT-IR data of compounds I, A, 1 and 2 is given in Table 1. The phosphorus chemical shift, δ(31P), shifts to down field from compound I to A, 1 and 2 so that the δ(31P) is the most down fielded in 2 (13.91 ppm). This down field shift shows the most electron withdrawing of substituents on the phosphorus atom in 2 resulting in the most deshielded phosphorus atom. Also, comparing the δ(31P) of complexes 1 and 2 confirms that copper(II) acetate can create a more positive phosphorus center than does the copper(II) nitrate. The 1H NMR spectrum of compound I reveals 2J(PNH) coupling constant equal to 10.6 Hz while it disappears in the spectra of A, 1 and 2. The 13C NMR spectra indicate that 3J(P,Caromatic) coupling constant decreases from 9.0 Hz (in I) to 7.0 Hz (in A), 6.9 Hz (in 1) and 6.2 Hz (in 2). Similarly, the 3J(P,Caliphatic) coupling constant decreases from 5.7 Hz (in A) to 5.4 Hz (in 1) and it vanishes in 2. These trends are indicative of weakening the interactions between phosphorus and ipso/ring-CH2 carbon atoms of 4-nitroanilinyl/morpholinyl ring in this series owing to the electronic and steric effects. Comparable splittings were also observed for our previously reported phosphoramide derivatives (Gholivand et al., 2005, 2006b).
| Compound | δ(31P) (ppm) | 2J(PNH) (Hz) | 3J(P,C) (Hz) | ν(P⚌O) (cm−1) | ν(P—N) (cm−1) | ν(N—H) (cm−1) | Ref. |
|---|---|---|---|---|---|---|---|
| Ia | 6.34 | 10.6 | 9.0 (aromatic) | 1249 | 942 | 3400 | Gholivand et al. (2005) |
| Ab | 9.99 | – | 7.0 (aromatic), 5.7 (aliphatic) | 1196 | 1104, 964 | 3425 | Gholivand et al. (2005) |
| 1 | 11.81 | – | 6.9 (aromatic), 5.4 (aliphatic) | 1204 | 1103, 968 | 3369 | This work |
| 2 | 13.91 | – | 6.2 (aromatic) | 1206 | 1101, 989 | 3487 | This work |
The FT-IR spectra illustrate that among these compounds, the ν(P⚌O) value decreases from I (1249 cm−1) to A (1169 cm−1) and 1, 2 (1204, 1206 cm−1) exhibiting the weakening of the P⚌O bonds. The ν(P—N) increases from 942 cm−1 (in I) to 964 cm−1 (in A), 968 cm−1 (in 1) and 989 cm−1 (in 2) that is due to the enhanced interaction of phosphorus atom with nitrogen lone pair to form a stronger partial multiple bond. Also, the NH stretching frequencies are observed around 3400 cm−1.
The UV–visible spectra display the maximum absorption wavelengths at 323, 333 and 350 nm for compounds A, 1 and 2, respectively that can be related to the interligand π → π∗ and n → π∗ transitions in A as well as LMCT (ligand to metal charge transfer)/MLCT (metal to ligand charge transfer) electronic transitions in 1 and 2. It is obvious that the λ(max) of absorption shifts to greater values (redshift) upon complexation. In addition, a redshift is observed from 1 to 2 that can be owing to the different electronic nature of copper(II) nitrate compared with that of copper(II) acetate. This is probably because of more stabilization of n/π bonding but more destabilization of σ∗/π∗ antibonding orbitals in 2 than in 1. It was shown that the chromium complexes of O,O′-dihydroxyazo dyes indicate strong absorption bands in the UV–Vis spectra within the range 420–495 nm that were characteristic for the azo and hydrazone compounds (Kocaokutgen and Özkınalı, 2004).
The fluorescence spectra of compounds A, 1 and 2 are presented in Fig. 1 showing the λ(max) of emission signals appear at 384, 360 and 390.5 nm, respectively. A blueshift is seen for the λ(max) of emission from A to 1 while a redshift is detected for 2. The band gaps (Eg) measured for compounds A, 1 and 2 are 3.23, 3.44 and 3.18 eV, respectively exhibiting the band gap increases in 1 but it decreases in 2 upon complexation. The differences in the emission behaviors of complexes 1 and 2 relative to their corresponding phosphoric triamide ligand A can be attributed to the diverse electronic nature of copper(II) acetate relative to that of copper(II) nitrate. It was exhibited that the UV–Vis and fluorescence spectra of cyclopentadienyliron azo complexes have broad absorption and emissions ranging from 352–412 nm and 300–450 nm, respectively, that were attributed to the π–π∗ transition within the cyclopentadiene moiety (Li et al., 2012).
The nanoparticles of compounds 1 and 2 were prepared by ultrasonic irradiation method and their FE-SEM micrographs are shown in Fig. 2 indicating the spherical morphology for the particles that are about 17–20 nm in size. The synthesis of nanosized organotin(IV) complexes of phosphoramides was already investigated using ultrasonic method (Shariatinia et al., 2013b).
The XRD patterns in Fig. 3 reveal sharp peaks due to high crystallinity with the sharpest peaks for compounds 1 and 2 appear at 2θ values of 16.60° and 20.14°, respectively. The Debye–Scherrer equation (d = 0.9 λ/β cos θ) (Klug and Alexander, 1954) was used to evaluate the average crystallite sizes where d is the average crystallite size, λ is the X-ray wavelength, β is the full width at half maximum (FWHM) and θ is the diffraction angle. The crystal sizes of complexes 1 and 2 were measured from the XRD diagrams equal to 36.99 and 32.67 nm, respectively.
3.2 Dyeing wool and nylon fibers
To evaluate the dyeing abilities of complexes 1 and 2, their UV–visible spectra were obtained at five different concentrations (1%, 2%, 3%, 4%, 5%). According to Beer–Lambert law, A = εbC, the plots of absorbance (A) against concentration (C) yielded the extinction coefficients (ε) equal to 13,859 and 12,645 mol−1 cm−1 for dyes 1 and 2, respectively, indicating these complexes are suitable dyes for dyeing fibers. Consequently, these complexes were used as dyes for dyeing wool, nylon, polyester and acrylic. The dyeing experiments were completely successful on wool and nylon fibers while the polyester and acrylic did not indicate remarkable color changes. Therefore, the wool and nylon fibers were selected for dyeing with these colorful complexes.
Table 2 presents the reflectance (R) and color strength (K/S) values for wool and nylon fibers dyed with five various concentrations (from 0.1% to 0.5% o.w.f.) of dyes 1 and 2. It is seen that with increasing the dye concentration, the K/S value increases for both wool and nylon fibers with the optimum concentration is 0.4% and after that the K/S ratio becomes constant (Fig. 4). However, the reflectance is reduced with increasing the dye concentration. These results confirm that increasing the dye concentration leads to a stronger color on both fibers. Figs. 5 and 6 clearly support these findings. Interestingly, it is observed in these figures that the color of both raw nylon and wool fibers is white before dyeing but the color of dyed fibers changes to yellow and green, respectively, using both dyes 1 and 2. Also, increasing the dye concentration from 0.1% to 0.5% produces a stronger color on both fibers.
| Dye | Concentration (%) | Fiber | R | K/S |
|---|---|---|---|---|
| 1 | 0.1 | Wool | 2.531 | 18.768 |
| 0.2 | Wool | 2.039 | 23.532 | |
| 0.3 | Wool | 1.914 | 25.133 | |
| 0.4 | Wool | 1.838 | 26.213 | |
| 0.5 | Wool | 1.799 | 26.802 | |
| 0.1 | Nylon | 3.283 | 14.246 | |
| 0.2 | Nylon | 3.168 | 14.799 | |
| 0.3 | Nylon | 2.746 | 15.878 | |
| 0.4 | Nylon | 2.965 | 17.222 | |
| 0.5 | Nylon | 2.731 | 17.322 | |
| 2 | 0.1 | Wool | 2.525 | 18.815 |
| 0.2 | Wool | 1.970 | 24.391 | |
| 0.3 | Wool | 1.892 | 25.437 | |
| 0.4 | Wool | 1.854 | 25.978 | |
| 0.5 | Wool | 1.908 | 25.215 | |
| 0.1 | Nylon | 3.759 | 12.320 | |
| 0.2 | Nylon | 2.894 | 16.292 | |
| 0.3 | Nylon | 2.723 | 17.376 | |
| 0.4 | Nylon | 2.542 | 18.682 | |
| 0.5 | Nylon | 2.588 | 18.333 | |
Table 3 displays the dyeing properties of wool and nylon fibers dyed with various concentrations (o.w.f.) of dyes 1 and 2. It is seen that in all cases the lightness (L∗) is reduced with increasing the dye concentration. The hue angles (h) range between 80 and 120 degrees representing a color between yellow and green. Moreover, according to LAB, negative values of a∗ and positive values of b∗ confirm that the color of dyed fibers is yellowish-green (Table 3). The plots of a∗ against b∗ for nylon and wool fibers dyed with complexes 1 and 2 are given in Fig. 7.
| Dye | Concentration (%) | Fiber | L∗ | c∗ | h° | a∗ | b∗ |
|---|---|---|---|---|---|---|---|
| 1 | 0.1 | Wool | 59.280 | 26.449 | 111.232 | −9.578 | 24.654 |
| 0.2 | Wool | 55.841 | 30.833 | 109.093 | −10.086 | 29.137 | |
| 0.3 | Wool | 56.074 | 30.748 | 110.601 | −10.819 | 28.782 | |
| 0.4 | Wool | 57.141 | 30.306 | 115.516 | −13.055 | 27.350 | |
| 0.5 | Wool | 56.616 | 31.311 | 114.157 | −12.814 | 28.569 | |
| 0.1 | Nylon | 87.425 | 36.383 | 106.582 | −10.383 | 34.870 | |
| 0.2 | Nylon | 87.700 | 36.377 | 106.415 | −10.280 | 34.895 | |
| 0.3 | Nylon | 85.595 | 41.367 | 107.615 | −12.518 | 39.427 | |
| 0.4 | Nylon | 85.902 | 45.413 | 106.156 | −12.636 | 43.619 | |
| 0.5 | Nylon | 85.094 | 43.656 | 105.041 | −11.329 | 42.161 | |
| 2 | 0.1 | Wool | 61.386 | 32.081 | 115.165 | −13.642 | 29.036 |
| 0.2 | Wool | 57.316 | 35.475 | 117.018 | −16.115 | 31.603 | |
| 0.3 | Wool | 55.946 | 37.476 | 114.345 | −15.449 | 34.144 | |
| 0.4 | Wool | 55.968 | 38.303 | 114.476 | −15.869 | 34.861 | |
| 0.5 | Wool | 52.674 | 37.365 | 109.595 | −12.531 | 35.201 | |
| 0.1 | Nylon | 86.825 | 36.632 | 105.893 | −10.031 | 35.232 | |
| 0.2 | Nylon | 84.685 | 40.672 | 106.977 | −11.876 | 38.900 | |
| 0.3 | Nylon | 82.333 | 50.322 | 101.874 | −10.354 | 49.245 | |
| 0.4 | Nylon | 83.567 | 49.231 | 102.983 | −11.060 | 47.973 | |
| 0.5 | Nylon | 79.338 | 51.139 | 97.366 | −6.556 | 50.717 | |
The washfastness tests were performed to evaluate the possibility of color change or staining of the dyed fibers. The lightfastness tests reveal the stability of the dyed fibers against light radiation. The results are shown in Table 4 and Figs. 8 and 9 for the dyed fibers with complexes 1 and 2, respectively. The numbers 5 or 4–5 are very appropriate for washfastness illustrating the constant color on the fibers but the lightfastness of 2 for both fibers confirming their changes by light irradiation. It was revealed that the appropriate lightfastness results can be obtained for the chromium complexes of O,O′-dihydroxyazo dyes [23] and also for the cyclopentadienyliron azo complexes (Li et al., 2012).
| Dye | Fiber | Cross-staining on nylon | Cross-staining on wool | Cross-staining color change | Color change |
|---|---|---|---|---|---|
| 1 | Wool | – | 5 | 5 | 5 |
| Nylon | 5 | – | 4–5 | 5 | |
| 2 | Wool | – | 5 | 5 | 4–5 |
| Nylon | 5 | – | 4–5 | 4–5 | |
In order to approve the presence of dyes 1 and 2 on the wool and nylon fibers, the FE-SEM images of raw wool/nylon fibers and wool/nylon fibers dyed with 0.3% o.w.f. of compounds 1 and 2 are given in Figs. 10 and 11. It can be seen that there are some particles on the surfaces of wool/nylon fibers reflecting that the dyes 1 and 2 are adsorbed onto the surfaces of the fibers.
3.3 Antibacterial activity
In order to explore the antibacterial potencies of the dyes and also the dyed fibers, the in vitro antibacterial activities of the dyes 1, 2 and wool/nylon fibers dyed with five different concentrations of these dyes (0.1–0.5% o.w.f.) were performed using the Gram-positive Bacillus subtilis bacterium. Each experiment was repeated for at least three times and the best results are summarized in Table 5. The Bacillus subtilis bacterium is known as a normal gut commensal in humans and is commonly found in soil (Hong et al., 2009). The bacteria of Bacillus family can produce toxins that may cause two types of illnesses including diarrhea and emetic toxin (nausea and vomiting) (Ryan and Ray, 2004; Asaeda et al., 2005).
| Sample | Inhibition zone | Sample | Inhibition zone |
|---|---|---|---|
| 1 | 9.62 | 2 | 10.15 |
| 0.1% of 1 on nylon | 9.59 | 0.1% of 2 on nylon | 10.48 |
| 0.2% of 1 on nylon | 10.67 | 0.2% of 2 on nylon | 11.31 |
| 0.3% of 1 on nylon | 11.53 | 0.3% of 2 on nylon | 12.42 |
| 0.4% of 1 on nylon | 12.40 | 0.4% of 2 on nylon | 13.60 |
| 0.5% of 1 on nylon | 13.96 | 0.5% of 2 on nylon | 15.23 |
| 0.1% of 1 on wool | 16.33 | 0.1% of 2 on wool | 17.12 |
| 0.2% of 1 on wool | 17.00 | 0.2% of 2 on wool | 18.38 |
| 0.3% of 1 on wool | 18.33 | 0.3% of 2 on wool | 19.11 |
| 0.4% of 1 on wool | 19.00 | 0.4% of 2 on wool | 20.32 |
| 0.5% of 1 on wool | 20.94 | 0.5% of 2 on wool | 21.98 |
The digital photographs of the antibacterial effects against Bacillus subtilis bacterium for the wool fibers dyed with 0.1–0.5% o.w.f. concentrations of dye 1 are indicated in Fig. 12. Similar results were observed for nylon fibers and also for the fibers dyed with compound 2. Comparing the inhibition zones (mm), it is found that the antibacterial effect is increased by increasing the dye concentration from 0.1% to 0.5% in both wool and nylon fibers. Therefore, it can be said that these dyed fibers can be used as antibacterial fibers in producing hygiene related textiles.
4 Conclusion
In summary, using ultrasonic irradiation, two novel nanosized copper(II) complexes were synthesized and fully characterized by NMR, FT-IR, fluorescence, UV–visible spectroscopy, XRD and FE-SEM microscopy. The FE-SEM images indicated the nanometer size and spherical morphology for the complexes. Application of the two yellowish-green complexes as disperse dyes in coloring nylon and wool fibers yielded yellow and green colored fibers, respectively. According to the CIELab tests, the best washfastness while poor lightfastness results were obtained for the dyed fibers. The in vitro antibacterial activities against Gram-positive Bacillus subtilis bacterium were enhanced by increasing the dye concentration on both wool and nylon dyed fibers.
Acknowledgment
The financial supports of this work by the Research Office of Amirkabir University of Technology (Polytechnic) are gratefully acknowledged.
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