Abstract
In the recent years, the medical sector is getting increasingly interested in the wound dressing materials that contain medicinal herb instead of metal nanoparticles to impart antibacterial or other desirable properties. Herein, a novel multicomponent nanofibrous mat has been successfully prepared by electrospinning technique from a blended solution of polyvinyl alcohol, honey and
Introduction
The practice of using medicinal plants to treat human skin including healing of wounds and burn injuries, antifungal, antiviral, antibacterial applications against skin infections has long history and is going on for primary healthcare even in the modern age [1]. Usually, wound dressing materials are broadly used for the treatment of skin wounds which are basically prepared from the textile fabric incorporating metal nanoparticles to impart antibacterial or other desirable properties. The requirements including maintaining a local moist environment, protect the wound from side-infection, minimize the wound surface necrosis, prevent the wound dryness, biocompatibility and biodegradability are some notable criteria for a material to be used as wound dressing materials [2–4]. Due to the usage of metal nanoparticles in the existing wound dressing materials, formation of similar materials using natural herbs like
The importance of biodegradable-biocompatible polymers such as polyvinyl alcohol (PVA), alginate, starch and chitosan or their derivatives has grown significantly over the past two decades due to their renewable and desirable biological properties [19]. These days PVA, being usually used as a carrier polymer during electrospinning, is one of the most frequent and synthetic polymer hydrogels because of its good biocompatibility finds applications in an advanced biomedical field including wound dressing and wound management [20], drug delivery system, artificial organs [21] and so on. Besides, because of its hydrogel-forming properties and ability to provide controlled release of antibiotics, PVA has turned out as a potential wound dressing material [22]. The permeability of PVA to small molecules, low interfacial tension, soft consistency and transparency also contribute toward its promising application for wound dressing purpose [23].
Turmeric (
The prominent wound healing as well as antibacterial properties of honey has made it another potential candidate for wound treatment of skin [41]. Honey has long been used for injury dressing [42] and has significant therapeutic and dietary properties as it demonstrates antimicrobial action, deriding and freshening up activity against inflammation [43], cell reinforcement and wound recuperating activities [44]. The physical properties of honey impact the injury mending condition and the recuperating procedure, particularly on the grounds that honey is acidic and has pH of around 3.2–5.0 [45]. Honey being rich in sugar, however, its low water content and acidic nature disfavor microbial development. Honey produces hydrogen peroxide with the actuating of the catalyst glucose oxidase, which oxidizes glucose to gluconic acid and hydrogen peroxide [46]. Utilization of sugar to enhance wound mending has been accounted for a few hundred patients [47]. In addition, honey has been viewed as having explicit antibacterial properties against
The formation of nanofibrous mats from the individual solution system of turmeric extract and honey mixing with different synthetic and natural ingredients has been enriched by several studies [51–53], but their synergistic effects on nanofibrous mat has not yet been studied thoroughly. Thus, the newness of the present study is to fabricate nanofibrous mat with honey and turmeric extract to explore their combined medicinal properties.
Experimental
Materials
First, turmeric was collected from local market in Gazipur city, Bangladesh. Locally produced pure honey was purchased from Sawpna super shop located in Gazipur, Bangladesh. PVA with molecular weight (MW) of 115,000, Degree of polymerization (DP) of 1700–1800, viscosity: 26–32 cps, 99% hydrolyzed granules were sourced from Loba Chemical Pvt. Ltd. (India). Reagent grade acetic acid (99.7%) and ethyl acetate with purity of 99% were purchased from Merck, Germany. All the chemicals and solvents were used without further purification.
Preparation of turmeric extract
Prior to extraction, turmeric was checked to ensure that materials are free from dirt and impurities. Then, a small piece of turmeric was oven-dried at 45°C and was ground using an electronic grinder at room temperature. The powder samples were soaked three times in ethyl acetate overnight at a ratio of 1:10 (w/v%) [54]. The crude extract of turmeric was then filtered through nylon mesh three times. Finally, the solvent was removed from the turmeric extracts at 40°C by magnetic stirrer and was kept it at 4°C for further use.
Preparation of PVA solution
PVA (10 g) was mixed with 90 mL deionized water to obtain 10 wt % (w/v) solution. The mixture was stirred and heated to 80°C to get a clear and transparent solution.
Preparation of electrospinning solution
Two electrospinning solutions were prepared to develop nanofibrous mat from the mixer of PVA-honey-turmeric at two mixing ratios. First solution being identified as CL-1 was prepared by adding 1 g of turmeric extract to 10 mL honey and 20 mL PVA solution and stirred at warming condition until a homogeneous solution is obtained. Another solution being identified as CL-2 was made by adding 2 g turmeric extract to 15 mL PVA and 15 mL honey and stirred as before to make it homogeneous. After preparation, both solutions were cooled to at room temperature. Although it is possible to produce nanofibrous mats using less than 1 g and more than 2 g turmeric extract, they are less potential and sticky which render their applications. Besides, the nanomat which contains more extract provides more antibacterial actions.
Electrospinning process
The prepared two solutions were loaded into a pump of electrospinning machine (model: TL-Pro-BM, company: Tong Li Tech, origin: China). The electrospining setup consists of a high voltage supply (–20 kV and +50 V), a syringe pump (TL-F6, Tong Li Tech, China), a rotary drum collector (diameter: 158 mm, length: 500 mm, 500 r/min), a syringe (30 mL), a heater (0.5 kW) and 5 needles (20 Gauge). The collector drum was wrapped with aluminium foil upon which nanomats was collected and connected with negative voltage. Optimum electrospinning condition was adjusted by trial and error method at ambient condition of 65% relative humidity and at 27°C.
Characterization
Morphological analysis
The orientation of nanofibers along with their diameter was measured by scanning electron microscope (SU 1510, Hitachi, Japan) at different magnifications. At least five different positions on the fibrous mats were captured to determine the diameter of the electrospun fibers. The fiber diameters were analyzed where 30 fibers were taken as a sample and frequency was measured with their particular diameter.
Measurement of moisture management properties
Moisture management properties of the developed mats were evaluated by a moisture management tester (MMT; M290, SDL Atlas, UK) according to the method of AATCC 195-2009. Wetting time, absorption rate, maximum wetted radius and spreading speed of inner and outer surface including accumulative one-way transport capacity (R) and overall moisture management capacity (OMMC) were evaluated following the above-mentioned standard to categorize the mat according to its interaction with liquid. The test was conducted using a saline solution which consists of 0.9% sodium chloride and 120-s measuring time to evaluate the moisture properties.
Antibacterial assay
Antibacterial activity of the electrospun nanofibrous mat was studied using disc diffusion method against
Fourier-transform infrared spectroscopy analysis
The chemical structure of PVA nanofiber, CL-1 and CL-2 was characterized using Fourier-transform infrared spectroscopy (FTIR; IRPrestige21, Shimadzu Corporation, Japan). The spectra of the samples were recorded at 698–4000cm−1 range with 4 cm−1 resolution.
Result and discussion
Parameters optimization and morphological observation
The parameters of electrospinning were considered as voltage, pressure, ambient condition, heater power and collector distance. The optimum electrospinning conditions were achieved by trial and error method at –12.3 kV, +23 kV, 0.45 kW with a flow rate of 1.5 mL per hour under ambient condition of 65% relative humidity and at 27°C, respectively. No fiber is formed when the applied voltage is less than 12 kV because it cannot overcome the surface tension value of the solution which restricts the solution to flow towards the collector. Hence, a higher than 12 kV voltage difference was maintained for all samples. However, a constant collector distance was maintained (which is 15 cm for all samples) as collector distance affect the diameter of fibers. The scanning electron microscope (SEM) images of the developed samples are shown in Figure 1 which reflects the formation of smooth nanofiber for all samples having an average diameter of 340 nm and Figure 2 indicates for route of forming mats.

SEM images at (a) 5 kV, ×5k; (b) 5 kV, ×10k; (c) 15 kV, ×5K and (d) fiber diameter [55] distributions with respective frequency.

Sequence of developed nanofibrous mats. PVA: polyvinyl alcohol.
Analysis of moisture management properties
Along with other properties, the moisture behavior of a nanofibrous mat has great importance to be used as wound dressing materials since a moist condition is necessary for wound healing purpose. Hence, it is important to evaluate the capacity for transferring liquids from microclimate to external environment. The results of moisture management properties of PVA nanomat, CL-1 and CL-2 have been presented in Figure 3. The wetting time (s) of the PVA, CL-1 and CL-2 shows the same pattern in both surface of the mats which may be due to their favorable interaction with liquids. But in case of inner surface, i.e., the side of the mat which is in touch with skin, the absorption rate, wetted radius and spreading speed is higher for CL-1 and CL-2. This may be attributed to the reduction in adhesive property of the PVA polymer because of mixing honey and turmeric extract. The greater spreading speed indicates their fast absorbing nature which is very crucial for wound healing activity. This nature of the developed mat can prevent it from being wetted very quickly due to the absorption of liquids from wound area. On the other hand, in case of outer surface (which is exposed to external environment); the result of all above-mentioned parameters follow the same pattern excluding the wetted radius for CL-2. This may be happening due to poor one-way transport capacity of CL-2 which might arose due to the higher content of honey and turmeric extract. However, the value of one-way transport capacity and OMMC has been calculated using all parameters that indicate that the PVA mat is poor in moisture transport property and thus should be considered as water repellent whereas CL-1 and CL-2 have been considered as fast absorbing and slow drying as well as fast absorbing and quick drying fabric, respectively. This fast absorbing nature will allow them to absorb the wound liquid very quickly from the wound area and transfer it to outer surface leading to enhanced healing performances.

Water location and time diagram (a to c) and quantitative grading of moisture behavior of PVA nanomat, CL-1 and CL-2 (a1 to c1). PVA: polyvinyl alcohol.
Antibacterial assay
The bacterial invasion into human tissue and cells is one of the most remarkable mechanisms in skin infection [56]. Among all,

Formation of zone of inhibition of (a) PVA nanofiber and (b) CL-1 and CL-2.
Antibacterial activity (zone of inhibition) of the samples.
PVA: polyvinyl alcohol; ZOI: zone of inhibition.

Mechanism of killing
Fourier-transform infrared spectroscopy
Infrared spectroscopy confirmed the presence of functional group of PVA, honey and turmeric extract in the developed sample as shown in Figure 6. The functional group region is identified in the range of 4000–1450cm−1 whereas the finger print region corresponds to the region of 1450–500 cm−1.

FTIR spectra of CL-1 and CL-2, respectively.
Besides the attributable peaks have been found at 3433 cm−1 (O–H stretching), 2927 cm−1 (C–H stretching) and 1095 cm−1 (C–O–C stretching) in case of PVA nanofiber. This is in agreement with the signature peaks of PVA as reported in previous studies [63]. The band spectra at 1600–1650 cm−1 and 1510 cm−1 show the presence of carbonyl group and the ethylene group of turmeric extract. The peaks at 725 cm−1, 817 cm−1 and 967 cm−1 indicated the bending vibrations of –CH bond of alkene group. Besides, the peak at 1250 cm−1 corresponds to C–O stretching of ether group in curcumin. The peak around 1500–1400 cm−1 indicated the –C–O elongation frequency of –OH groups in curcumin [64]. Without this, the band spectra at 1270 cm−1 corresponds to C–O stretching of honey [65].
Conclusion
In this research, the optimum processing condition for the fabrication of PVA–honey nanofibrous mats laden with turmeric extract have been presented. Here, samples were developed through electrospinning method at two mixing ratios and then they were characterized. SEM, MMT, antibacterial assay and FTIR were used to characterize the prepared nanofibrous mats. The result of FTIR confirmed a presence of PVA, honey and turmeric extract compounds by showing their characteristic peaks. The PVA–honey nanofibrous mats loaded with turmeric extract exhibited enhanced moisture management properties. Due to the presence of antibacterial constituents of honey and turmeric extract, the developed samples showed the formation of inhibition of 29 mm and 38 mm, whereas no inhibition zone was formed for PVA nanofiber alone for the same bacteria. These properties indicate that the developed nanomats could be used as potential wound dressing materials and in tissue engineering. This multicomponent combination could lead to a wide range of applications in various engineering fields.
Footnotes
Acknowledgements
The authors are grateful to the Department of Textile Engineering, Dhaka University of Engineering and Technology, Gazipur, for permitting to use its lab facility. A special gratitude is also extended to the Department of Biochemistry, University of Dhaka for providing antibacterial test facilities for this research.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest regarding this research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
