Lignin-mediated in-situ synthesis of CuO nanoparticles on cellulose nanofibers: A potential wound dressing material

Electrospun nanofibers synthesized from polymers incorporated with bioactive compounds for wound healing

The development of innovative wound dressing materials is crucial for effective wound care. It's an active area of research driven by a better understanding of chronic wound pathogenesis. Addressing wound care properly is a clinical challenge, but there is a growing demand for advancements in this field. The synergy of medicinal plants and nanotechnology offers a promising approach to expedite the healing process for both acute and chronic wounds by facilitating the appropriate progression through various healing phases. Metal nanoparticles play an increasingly pivotal role in promoting efficient wound healing and preventing secondary bacterial infections. Their small size and high surface area facilitate enhanced biological interaction and penetration at the wound site. Specifically designed for topical drug delivery, these nanoparticles enable the sustained release of therapeutic molecules, such as growth factors and antibiotics. This targeted approach ensures optimal cell-to-cell interactions, proliferation, and vascularization, fostering effective and controlled wound healing. Nanoscale scaffolds have significant attention due to their attractive properties, including delivery capacity, high porosity and high surface area. They mimic the Extracellular matrix (ECM) and hence biocompatible. In response to the alarming rise of antibiotic-resistant, biohybrid nanofibrous wound dressings are gradually replacing conventional antibiotic delivery systems. This emerging class of wound dressings comprises biopolymeric nanofibers with inherent antibacterial properties, nature-derived compounds, and biofunctional agents. Nanotechnology, diminutive nanomaterials, nanoscaffolds, nanofibers, and biomaterials are harnessed for targeted drug delivery aimed at wound healing. This review article discusses the effects of nanofibrous scaffolds loaded with nanoparticles on wound healing, including biological (in vivo and in vitro) and mechanical outcomes.

Trends in the Incorporation of Antiseptics into Natural Polymer-Based Nanofibrous Mats

Nanofibrous materials represent a very promising form of advanced carrier systems that can be used industrially, especially in regenerative medicine as highly functional bandages, or advanced wound dressings. By incorporation of antimicrobial additives directly into the structure of the nanofiber carrier, the functionality of the layer is upgraded, depending on the final requirement-bactericidal, bacteriostatic, antiseptic, or a generally antimicrobial effect. Such highly functional nanofibrous layers can be prepared mostly by electrospinning technology from both synthetic and natural polymers. The presence of a natural polymer in the composition is very advantageous. Especially in medical applications where, due to the presence of the material close to the human body, the healing process is more efficient and without the occurrence of an unwanted inflammatory response. However, converting natural polymers into nanofibrous form, with a homogeneously distributed and stable additive, is a great challenge. Thus, a combination of natural and synthetic materials is often used. This review clearly summarizes the issue of the incorporation and effectiveness of different types of antimicrobial substances, such as nanoparticles, antibiotics, common antiseptics, or substances of natural origin, into electrospun nanofibrous layers made of mostly natural polymer materials. A section describing the problematic aspects of antimicrobial polymers is also included.

Lignin-facilitated growth of Ag/CuNPs on surface-activated polyacryloamidoxime nanofibers for superior antibacterial activity with improved biocompatibility

INTRODUCTION

Nanofibers are one of the role-playing innovations of nanotechnology. Their high surface-to-volume ratio allows them to be actively functionalized with a wide range of materials for a variety of applications. The functionalization of nanofibers with different metal nanoparticles (NPs) has been studied widely to fabricate antibacterial substrates to battle antibiotic-resistant bacteria. However, metal NPs show cytotoxicity to living cells, thereby restricting their application in biomedicine.

OBJECTIVES

To minimize the cytotoxicity of NPs, biomacromolecule lignin was employed as both a reducing and capping agent to green synthesize silver (Ag) and copper (Cu) NPs on the surface of highly activated polyacryloamidoxime nanofibers. The activation of polyacrylonitrile (PAN) nanofibers via amidoximation was employed for enhanced loading of NPs to achieve superior antibacterial activity.

METHODOLOGY

At first, electrospun PAN nanofibers (PANNM) were activated to produce polyacryloamidoxime nanofibers (AO-PANNM) by immersing PANNM in a solution of Hydroxylamine hydrochloride (HH) and Na₂CO₃ under controlled conditions. Later, Ag and Cu ions were loaded by immersing AO-PANNM in different molar concentrations of AgNO₃ and CuSO₄ solutions in a stepwise manner. The reduction of Ag and Cu ions into NPs to fabricate bimetal-coated PANNM (BM-PANNM) was carried out via alkali lignin at 37 °C for 3 h in a shaking incubator with ultrasonication every 1 h.

RESULTS

AO-APNNM and BM-PANNM hold their nano-morphology except for some changes in fiber orientation. XRD analysis demonstrated the formation of Ag and CuNPs as evident from their respective spectral band. Maximum 8.46 ± 0.14 wt% and 0.98 ± 0.04 wt% Ag and Cu species were loaded on AO-PANNM, respectively as revealed by ICP spectrometric analysis. The hydrophobic PANNM turned into super hydrophilic, having WCA of 14 ± 3.32° after amidoximation which further reduced to 0° for BM-PANNM. However, the swelling ratio of PANNM reduced from 13.19 ± 0.18 g/g to 3.72 ± 0.20 g/g for AO-PANNM. Even at the third cycle test against S. aureus strains, 0.1Ag/Cu-PANNM, 0.3Ag/Cu-PANNM, and 0.5Ag/Cu-PANNM displayed bacterial reduction of 71.3 ± 1.64 %, 75.2 ± 1.91 %, and 77.24 ± 1.25 %, respectively. On 3rd cycle test against E. coli, above 82 % bacterial reduction was noticed for all BM-PANNM. Amidoximation increased COS-7 cell viability up to 82 %. The cell viability of 0.1Ag/Cu-PANNM, 0.3Ag/Cu-PANNM, and 0.5Ag/Cu-PANNM was found to be ~68 %, ~62, and 54 %, respectively. In LDH assay, almost no release of LDH was detected, suggesting the compatibility of the cell membrane in contact with BM-PANNM. The improved biocompatibility of BM-PANNM even at higher loading (%) of NPs must be ascribed to the controlled release of metal species in the early stage, antioxidant, and biocompatible lignin capping of NPs.

CONCLUSIONS

BM-PANNM displayed superior antibacterial activity against E. coli and S. aureus bacterial strains and acceptable biocompatibility of COS-7 cells even at higher loading (%) of Ag/CuNPs. Our findings suggest that BM-PANNM can be used as a potential antibacterial wound dressing and other antibacterial applications where sustained antibacterial activity is needed.

A functional lignin for heavy metal ions adsorption and wound care dressing

Recently, the application of lignin activation by demethylation to improve reactivity and enrich multiple functions has intensively attracted attention. However, it is still challenge up to now due to the low reactivity and complexity of lignin structure. Here, an effective demethylation way was explored by microwave-assisted method for substantially enhancing the hydroxyl (-OH) content and retaining the structure of lignin. Then, the optimum demethylated lignin was used to removal heavy metal ions and promote wound healing, respectively. In detail, for microwave-assisted demethylated poplar lignin (M-DPOL), the contents of phenolic (Ar-OH) and total hydroxyl (Tot-OH) groups reached the maximum for 60 min at 90 °C in DMF with 7.38 and 9.13 mmol/g, respectively. After demethylation, with this M-DPOL as lignin-based adsorbent, the maximum adsorption capacity (Q_max) for Pb²⁺ ions reached 104.16 mg/g. Based on the isotherm, kinetic and thermodynamic models analyses, the chemisorption occurred in monolayer on the surface of M-DPOL, and all adsorption processes were endothermic and spontaneous. Meanwhile, M-DPOL as a wound dressing had excellent antioxidant property, outstanding bactericidal activity and remarkable biocompatibility, suggesting that it did not interfere with cell proliferation. Besides, the wounded rats treated with M-DPOL significantly promoted its formation of re-epithelialization and wound healing of full-thickness skin defects. Overall, microwave-assisted method of demethylated lignin can offer great advantages for heavy metal ions removal and wound care dressing, which facilitates high value application of lignin.

High value valorization of lignin as environmental benign antimicrobial

Lignin is a natural aromatic polymer of p-hydroxyphenylpropanoids with various biological activities. Noticeably, plants have made use of lignin as biocides to defend themselves from pathogen microbial invasions. Thus, the use of isolated lignin as environmentally benign antimicrobial is believed to be a promising high value approach for lignin valorization. On the other hand, as green and sustainable product of plant photosynthesis, lignin should be beneficial to reduce the carbon footprint of antimicrobial industry. There have been many reports that make use of lignin to prepare antimicrobials for different applications. However, lignin is highly heterogeneous polymers different in their monomers, linkages, molecular weight, and functional groups. The structure and property relationship, and the mechanism of action of lignin as antimicrobial remains ambiguous. To show light on these issues, we reviewed the publications on lignin chemistry, antimicrobial activity of lignin models and isolated lignin and associated mechanism of actions, approaches in synthesis of lignin with improved antimicrobial activity, and the applications of lignin as antimicrobial in different fields. Hopefully, this review will help and inspire researchers in the preparation of lignin antimicrobial for their applications.

Titanium Dioxide/Chromium Oxide/Graphene Oxide Doped into Cellulose Acetate for Medical Applications

Wound dressings have been designed based on cellulose acetate encapsulated with different concentrations of chromium oxide (Cr₂O₃) and titanium oxide (TiO₂) with/without graphene oxide (GO). This study comprises the structural, morphological, optical, thermal, and biological behavior of chromium oxide/titanium dioxide/graphene oxide-integrated cellulose acetate (CA) films. The CA-based film bond formation was introduced by functional group analysis via Fourier transform infrared (FTIR) spectroscopy. The fabricated Cr₂O₃/TiO₂/GO@CA film SEM micrographs demonstrate transition metal oxides Cr₂O₃ and TiO₂ on a nano-scale. The TiO₂@CA shows the lowest contact angle with 30°. Optically, the refractive index increases from 1.76 for CA to 2.14 for the TiO₂@CA film. Moreover, normal lung cells (A138) growth examination in a function of Cr₂O₃/TiO₂/GO@CA film concentration is conducted, introducing 93.46% with the usage of 4.9 µg/mL. The resulting data showed a promising wound-healing behavior of the CA-based films.

Synthesized bioactive lignin nanoparticles/polycaprolactone nanofibers: A novel nanobiocomposite for bone tissue engineering

The use of artificial biomaterial with enhanced bioactivity for osteostimulation is a major research concern at present days. In this research, antibacterial and osteostimulative core-shell lignin nanoparticles (LgNP) were synthesized from alkali lignin using tetrahydrofuran (THF) as solvent via a simultaneous pH and solvent shifting technology. Later, LgNP-loaded polycaprolactone (PCL) composite nanofibers were fabricated via the electrospinning technique. The addition of LgNP significantly increased the diameter of the nanofibers, ranging from 400 to 2200 nm. The addition of LgNP reduced the mechanical performance, crystallinity, and porosity of the nanofibers while improving surface wetting and swelling properties of the inherently hydrophobic PCL polymer. The prepared nanofibers showed excellent bactericidal efficacy against major bone infectious Gram-positive Staphylococcus aureus bacterial strains. The incorporation of LgNP imparted superior antioxidant activity and boosted the biodegradation process of the nanofibers. The deposition of biomineral apatite with platelet-like clustered protrusions having a Ca/P ratio of 1.67 was observed while incubating the scaffold in simulated body fluid. Based on the results of the LDH and WST-1 assay, it was demonstrated that the composite nanofibers are non-toxic to pre-osteoblastic cell line (MC3T3-E1) when they are placed in direct contact with the LgNP/PCL scaffold nanofibers. The MC3T3-E1 cells exhibited excellent proliferation and attachment on the prepared composite scaffold via filopodial and lamellipodial expansion with cell-secreted Ca deposition. According to the alkaline phosphatase activity test, LgNP/PCL nanofiber scaffolds significantly improved osteogenic differentiation of MC3T3-E1 cells compared to neat PCL nanofibers. Overall, our findings suggest that LgNP/PCL nanofiber scaffold could be a promising functional biomaterial for bone tissue engineering.

Antibacterial lignin-based nanoparticles and their use in composite materials

Lignin, one of the most abundant biopolymers on earth, has been traditionally considered a low-value by-product of the pulp and paper industries. This renewable raw material, besides being a source of valuable molecules for the chemical industry, also has antioxidant, UV-absorbing, and antibacterial properties in its macromolecular form. Moreover, lignin in the form of nanoparticles (LigNPs) presents advantages over bulk lignin, such as higher reactivity due to its larger surface-to-volume ratio. In view of the rapid surge of antimicrobial resistance (AMR), caused by the overuse of antibiotics, continuous development of novel antibacterial agents is needed. The use of LigNPs as antibacterial agents is a suitable alternative to conventional antibiotics for topical application or chemical disinfectants for surfaces and packaging. Besides, their multiple and unspecific targets in the bacterial cell may prevent the emergence of AMR. This review summarizes the latest developments in antibacterial nano-formulated lignin, both in dispersion and embedded in materials. The following roles of lignin in the formulation of antibacterial NPs have been analyzed: (i) an antibacterial active in nanoformulations, (ii) a reducing and capping agent for antimicrobial metals, and (iii) a carrier of other antibacterial agents. Finally, the review covers the inclusion of LigNPs in films, fibers, hydrogels, and foams, for obtaining antibacterial lignin-based nanocomposites for a variety of applications, including food packaging, wound healing, and medical coatings.

Eggshell membrane-mimicking multifunctional nanofiber for in-situ skin wound healing

Eggshell membrane is a naturally-occurring protective barrier layer for chickens' incubation and shows the close similarity with extracellular matrix. To fully explore and utilize its' structure and active components via a mimicking way will be of great interest for wounds healing. Herein, the well-dispersed CuS nanoparticles were prepared by using eggshell membranes as templates with strong near-infrared absorption and photothermal properties. Furthermore, the as-prepared solution was combined with polyvinyl pyrrolidone and chitosan-derived fluorescent carbon dots for the mimetic synthesis of multifunctional nanofibrous membrane by a hand-held electrospinning device, which has the merits of in-situ operation, the extracellular matrix (ECM)-like architecture, hemostatic, radical scavenging, antibacterial, as well as accelerated healing of skin injury, etc. The electrospun-nanofiber membrane with optimal addition of 100 mg/L CuS nanoparticles was confirmed to be noncytotoxic on human fibroblasts and showed strong antibacterial activities against S. aureus and E. coli under NIR irradiation (980 nm). In addition, the radical scavenging ability was also proved by DPPH experiments. The animal experiments revealed that the nanofiber membrane could accelerate the wound healing process. The work lays down a simple and environmentally-friendly approach for the fabrication and development of promising wound healing materials in skin tissue engineering applications.

Development of PVA-Psyllium Husk Meshes via Emulsion Electrospinning: Preparation, Characterization, and Antibacterial Activity

In this study, polyvinyl alcohol (PVA) and psyllium husk (PSH)/D-limonene electrospun meshes were produced by emulsion electrospinning for use as substrates to prevent the growth of bacteria. D-limonene and modified microcrystalline cellulose (mMCC) were preferred as antibacterial agents. SEM micrographs showed that PVA–PSH electrospun mesh with a 4% amount of D-limonene has the best average fiber distribution with 298.38 ± 62.8 nm. Moreover, the fiber morphology disrupts with the addition of 6% D-limonene. FT-IR spectroscopy was used to analyze the chemical structure between matrix–antibacterial agents (mMCC and D-limonene). Although there were some partial physical interactions in the FT-IR spectrum, no chemical reactions were seen between the matrixes and the antibacterial agents. The thermal properties of the meshes were determined using thermal gravimetric analysis (TGA). The thermal stability of the samples increased with the addition of mMCC. Further, the PVA–PSH–mMCC mesh had the highest value of contact angle (81° ± 4.05). The antibacterial activity of functional meshes against Gram (−) (Escherichia coli, Pseudomonas aeruginosa) and Gram (+) bacteria (Staphylococcus aureus) was specified based on a zone inhibition test. PPMD6 meshes had the highest antibacterial results with 21 mm, 16 mm, and 15 mm against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, respectively. While increasing the amount of D-limonene enhanced the antibacterial activity, it significantly decreased the amount of release in cases of excess D-limonene amount. Due to good fiber morphology, the highest D-limonene release value (83.1%) was observed in PPMD4 functional meshes. The developed functional meshes can be utilized as wound dressing material based on our data.

Enhanced Spontaneous Antibacterial Activity of δ-MnO2 by Alkali Metals Doping

Recently, the widespread use of antibiotics is becoming a serious worldwide public health challenge, which causes antimicrobial resistance and the occurrence of superbugs. In this context, MnO₂ has been proposed as an alternative approach to achieve target antibacterial properties on Streptococcus mutans (S. mutans). This requires a further understanding on how to control and optimize antibacterial properties in these systems. We address this challenge by synthesizing δ-MnO₂ nanoflowers doped by magnesium (Mg), sodium (Na), and potassium (K) ions, thus displaying different bandgaps, to evaluate the effect of doping on the bacterial viability of S. mutans. All these samples demonstrated antibacterial activity from the spontaneous generation of reactive oxygen species (ROS) without external illumination, where doped MnO₂ can provide free electrons to induce the production of ROS, resulting in the antibacterial activity. Furthermore, it was observed that δ-MnO₂ with narrower bandgap displayed a superior ability to inhibit bacteria. The enhancement is mainly attributed to the higher doping levels, which provided more free electrons to generate ROS for antibacterial effects. Moreover, we found that δ-MnO₂ was attractive for in vivo applications, because it could nearly be degraded into Mn ions completely following the gradual addition of vitamin C. We believe that our results may provide meaningful insights for the design of inorganic antibacterial nanomaterials.

Multifunctional applications of natural polysaccharide starch and cellulose: An update on recent advances

The emergence of clinical complications and therapeutic challenges for treating various diseases necessitate the discovery of novel restorative functional materials. Polymer-based drug delivery systems have been extensively reported in the last two decades. Recently, there has been an increasing interest in the progression of natural biopolymers based controlled therapeutic strategies, especially in drug delivery and tissue engineering applications. However, the solubility and functionalisation due to their complex network structure and intramolecular bonding seem challenging. This review explores the current advancement and prospects of the most promising natural polymers such as cellulose, starch and their derivatives-based drug delivery vehicles like hydrogels, films and composites, in combating major ailments such as bone infections, microbial infections, and cancers. In addition, selective drug targeting using metal-drug (MD) and MD-based polymeric missiles have been exciting but challenging for its application in cancer therapeutics. Owing to high biocompatibility of starch and cellulose, these materials have been extensively evaluated in biomedical and pharmaceutical applications. This review presents a detailed impression of the current trends for the construction of biopolymer-based tissue engineering, drug/gene/protein delivery vehicles.

Biomedical Applications of Nanofibers

The idea of creating replacement for damaged or diseased tissue, which will mimic the physiological conditions and simultaneously promote regeneration by patients’ own cells, has been a major challenge in the biomedicine for more than a decade. Therefore, nanofibers are a promising solution to address these challenges. Nanofiber technology is an exciting area attracting the attention of many researchers as a potential solution to these current challenges in the biomedical field such as burn and wound care, organ repair, and treatment for osteoporosis and various diseases. Nanofibers mimic the porous topography of natural extracellular matrix (ECM), hence they are advantageous for tissue regeneration . In biomedical engineering, electrospinning exhibits advantages as a tissue engineering scaffolds producer, which can make appropriate resemblance in physical structure with ECM. This is because of the nanometer scale of ECM fibrils in diameter, which can be mimicked by electrospinning procedure as well as its porous structure. In this review, the applications of nanofibers in various biomedical areas such as tissue engineering, wound dressing and facemask, are summarized. It provides opportunities to develop new materials and techniques that improve the ability for developing quick, sensitive and reliable analytical techniques.

Recent Advances in the Fabrication and Environmental Science Applications of Cellulose Nanofibril-Based Functional Materials

Cellulose is one of the important biomass materials in nature and has shown wide applications in various fields from materials science, biomedicine, tissue engineering, wearable devices, energy, and environmental science, as well as many others. Due to their one-dimensional nanostructure, high specific surface area, excellent biodegradability, low cost, and high sustainability, cellulose nanofibrils/nanofibers (CNFs) have been widely used for environmental science applications in the last years. In this review, we summarize the advance in the design, synthesis, and water purification applications of CNF-based functional nanomaterials. To achieve this aim, we firstly introduce the synthesis and functionalization of CNFs, which are further extended for the formation of CNF hybrid materials by combining with other functional nanoscale building blocks, such as polymers, biomolecules, nanoparticles, carbon nanotubes, and two-dimensional (2D) materials. Then, the fabrication methods of CNF-based 2D membranes/films, three-dimensional (3D) hydrogels, and 3D aerogels are presented. Regarding the environmental science applications, CNF-based nanomaterials for the removal of metal ions, anions, organic dyes, oils, and bio-contents are demonstrated and discussed in detail. Finally, the challenges and outlooks in this promising research field are discussed. It is expected that this topical review will guide and inspire the design and fabrication of CNF-based novel nanomaterials with high sustainability for practical applications.

Rapid green-synthesis of TiO2 nanoparticles for therapeutic applications

Nanoparticles (NPs) with sizes ranging from 2 nm to 1 μm find various applications in the field of theranostics. Moreover, if eco-friendly methods are opted for the synthesis of biocompatible and less toxic NPs, then that's a huge success. Titanium dioxide nanoparticles (TiO₂ NPs) have been vigorously studied for their use in medical implants, photodynamic therapy, drug delivery, biosensing and as antimicrobial agents. The present study reports the green-synthesis of TiO₂ NPs for the first-time using extracts of black pepper (Piper nigrum), coriander (Coriandrum sativum) and clove (Syzygium aromaticum). All three samples of TiO₂ NPs were synthesized via a modified sol–gel method under similar environmental conditions. Similar treatments were given to the samples. The procedure adopted for the synthesis ensures the use of non-toxic materials, no production of toxic by-products and rapid synthesis of the TiO₂ NPs. The NPs were characterized by X-ray diffraction, high resolution-transmission electron microscopy, energy dispersive spectroscopy, field emission scanning electron microscopy and selected area electron diffraction which confirmed the formation, morphology, crystallinity and size of the TiO₂ NPs. These characterizations displayed the similarity index of all three samples. However, photoluminescence and vibrating sample magnetometer studies highlighted the differences among the three samples. All three samples of NPs obtained had a size range of 5–20 nm. Further, the findings showed that different plant extracts result in TiO₂ NPs with moderately different characteristics. Furthermore, the samples were analysed for their drug-encapsulation efficiency using UV-visible spectrophotometry. Among all three samples, the NPs synthesised using black pepper exhibited the maximum encapsulation efficiency. The study concludes that the plant's bio-profile is responsible for bringing about changes in the traits of the resulting nanoparticles. Thus, the extracts from different plants have the ability to manipulate the properties of the synthesized NPs. These findings can help to understand the role and importance of the plants in synthesizing NPs for biomedical applications. A further detailed study in this field can help researchers to understand the influence of the plant's biochemistry in shaping the NPs.

Synthesis of TiO₂ nanoparticles using three different plant extracts results in different properties of the individual samples.

Fabricating Antibacterial and Antioxidant Electrospun Hydrophilic Polyacrylonitrile Nanofibers Loaded with AgNPs by Lignin-Induced In-Situ Method

Concerning the environmental hazards owing to the chemical-based synthesis of silver nanoparticles (AgNPs), this study aimed to investigate the possibility of synthesizing AgNPs on the surface of polyacrylonitrile (PAN) nanofibers utilizing biomacromolecule lignin. SEM observations revealed that the average diameters of the produced nanofibers were slightly increased from ~512 nm to ~673 nm due to several factors like-swellings that happened during the salt treatment process, surface-bound lignin, and the presence of AgNPs. The presence of AgNPs was validated by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The amount of synthesized AgNPs on PAN nanofibers was found to be dependent on both precursor silver salt and reductant lignin concentration. Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectra confirm the presence of lignin on PAN nanofibers. Although the X-ray diffraction pattern did not show any AgNPs band, the reduced intensity of the stabilized PAN characteristics bands at 2θ = 17.28° and 29.38° demonstrated some misalignment of PAN polymeric chains. The water contact angle (WCA) of hydrophobic PAN nanofibers was reduced from 112.6 ± 4.16° to 21.4 ± 5.03° for the maximum AgNPs coated specimen. The prepared membranes exhibited low thermal stability and good swelling capacity up to 20.1 ± 0.92 g/g and 18.05 ± 0.68 g/g in distilled water and 0.9 wt% NaCl solution, respectively. Coated lignin imparts antioxidant activity up to 78.37 ± 0.12% at 12 h of incubation. The resultant nanofibrous membranes showed a proportional increase in antibacterial efficacy with the rise in AgNPs loading against both Gram-positive S. aureus and Gram-negative E. coli bacterial strains by disc diffusion test (AATCC 147-1998). Halos for maximum AgNPs loading was calculated to 18.89 ± 0.15 mm for S. aureus and 21.38 ± 0.17 mm for E. coli. An initial burst release of silver elements within 24 h was observed in the inductively coupled plasma-atomic emission spectrometry (ICP-AES) test, and the release amounts were proportionally expansive with the increase in Ag contents. Our results demonstrated that such types of composite nanofibers have a strong potential to be used in biomedicine.

Evaluating Antibacterial Efficacy and Biocompatibility of PAN Nanofibers Loaded with Diclofenac Sodium Salt

Side effects of the drugs’ oral administration led us to examine the possibility of using diclofenac sodium (DLF) in a polymeric drug delivery system based on electrospun polyacrylonitrile (PAN) nanofibers, which can be produced cost-effectively and with good applicability for transdermal treatments. The inclusion of DLF in PAN nanofibers increased the nanofiber diameter from ~200 nm to ~500 nm. This increase can be attributed to the increase in the spinning solution viscosity. FTIR spectra confirm the entrapment of the DLF into the PAN nanofibers. X-ray diffraction pattern showed that the inclusion of the DLF in the PAN nanofibers had caused the misalignment in the polymeric chains of the PAN, thus resulting in a decrease of the peak intensity at 2θ = 17^o. The DLF loaded PAN nanofibers were efficient against the gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli), with maximum inhibition zone of 16 ± 0.46 mm for E. coli and 15.5 ± 0.28 mm for S. aureus. Good cell viability ~95% for L929 cells in more extended incubation periods was reported. A gradual release of DLF from the PAN nanofiber was observed and can be attributed to the stability of Pan in PBS medium. Cell adhesion micrographs show that cell-cell interaction is stronger than the cell-material interaction. This type of weak cell interaction with the wound dressing is particularly advantageous, as this will not disturb the wound surface during the nursing of the wound.