Fabrication of centrifugally spun prepared poly(lactic acid)/gelatin/ciprofloxacin nanofibers for antimicrobial wound dressing

Centrifugal spinning is a novel technology for producing ultrafine fibers in high yield with diameters ranging from micro to nanometers. The obtained fibers have potential applications in the field of tissue engineering, wound dressing, and biomedicine etc. In this paper, a system of poly(lactic acid)/gelatin (PLA/GE) nanofibers loaded with ciprofloxacin (CPF) drug for wound dressings were successfully prepared by centrifugal spinning. The nanofibers were characterized by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). In addition, the nanofibers'' properties in terms of hydrophilicity, antibacterial properties and in vitro drug release were further investigated. The results showed that the CPF drug was successfully loaded and in an amorphous state in the PLA/GE nanofibers, the surface of the nanofibers was smooth and the nanofibers'' diameter became large after the drug was loaded. The thermal stability of the nanofiber was reduced while the hydrophilicity was improved. Antibacterial and in vitro drug release experiments showed that the nanofibers have obvious antibacterial properties and have the positive effect of sustained release of the drug. Drug-loaded PLA/GE nanofibers could be good candidates for wound dressing.

Centrifugal spinning is a novel technology for producing ultrafine fibers in high yield with diameters ranging from micro to nanometers.     

Toward improved wound dressings: effects of polydopamine-decorated poly(lactic-co-glycolic acid) electrospinning incorporating basic fibroblast growth factor and ponericin G1

Artificial dressings composed of degradable polymer materials have a wide range of applications in skin repair. The structure and properties, in particular, the antibacterial properties, of the material surface are crucial for biological processes such as cell adhesion, proliferation, and skin regeneration. In this study, we aimed to prepare poly(lactic-co-glycolic acid) (PLGA) nanofiber scaffolds modified by polydopamine using electrospinning technology in order to produce polydopamine-modified degradable PLGA nanocomposites. The polydopamine-PLGA scaffold was endowed with excellent protein adhesion ability through the cross-linking of two biologically active factors, basic fibroblast growth factor (bFGF) and ponericin G1, significantly improving skin repair ability. The electrospun nanofiber scaffold was shown to have a structure similar to that of the natural cell matrix and created a more favorable microenvironment for cell growth. Surface modification by polydopamine dramatically improved the hydrophilicity of the nanofiber scaffold, increasing its ability to absorb active factors and its biocompatibility. The bFGF and ponericin G1 loaded onto the scaffold surface (PDA-PLGA/bFGF/ponericin G1 nanofiber scaffold) strongly promoted the antibacterial and cell proliferation-promoting properties and greatly enhanced the adhesion and proliferation of cells on the scaffold surface. The nanofiber scaffold also promoted wound healing and tissue collagen production in a rat wound healing model. Together, these findings indicate that the polydopamine-PLGA/bFGF/ponericin G1 nanofiber scaffold exhibits good biocompatibility and antibacterial properties, suggesting that it possesses potential value for skin tissue regeneration applications.

Artificial dressings composed of degradable polymer materials have a wide range of applications in skin repair.     

Evaluation of a Nisin-Eluting Nanofiber Scaffold To Treat Staphylococcus aureus-Induced Skin Infections in Mice

Staphylococcus aureus is a virulent pathogen and a major causative agent of superficial and invasive skin and soft tissue infections (SSSTIs). Antibiotic resistance in S. aureus, among other bacterial pathogens, has rapidly increased, and this is placing an enormous burden on the health care sector and has serious implications for infected individuals, especially immunocompromised patients. Alternative treatments thus need to be explored to continue to successfully treat infections caused by S. aureus, including antibiotic-resistant strains of S. aureus. In this study, an antimicrobial nanofiber wound dressing was generated by electrospinning nisin (Nisaplin) into poly(ethylene oxide) and poly(d,l-lactide) (50:50) blend nanofibers. Active nisin diffused from the nanofiber wound dressings for at least 4 days in vitro, as shown by consecutive transfers onto plates seeded with strains of methicillin-resistant S. aureus (MRSA). The nisin-containing nanofiber wound dressings significantly reduced S. aureus Xen 36 bioluminescence in vivo and viable cell numbers in a murine excisional skin infection model. The bacterial burden of wounds treated with nisin-containing nanofiber wound dressings was 4.3 × 10² CFU/wound, whereas wounds treated with control nanofiber wound dressings had 2.2 × 10⁷ CFU/wound on the last day of the trial (day 7). Furthermore, the wound dressings stimulated wound closure of excisional wounds, and no adverse effects were observed by histological analysis. Nisin-containing nanofiber wound dressings have the potential to treat S. aureus skin infections and to potentially accelerate wound healing of excisional wounds.     

Sandwich structure Aloin-PVP/Aloin-PVP-PLA/PLA as a wound dressing to accelerate wound healing

We have prepared a new type of Aloin/Polyvinylpyrrolidone (PVP)-Aloin/PVP/polylactic acid (PLA)-PLA sandwich nanofiber membrane (APP), to achieve a time-regulated biphasic drug release behavior, used for hemostasis, antibacterial activity and accelerated wound healing. We tested the water absorption capacity, water contact angle, tensile strength, thermogravimetric analysis, Fourier transform infrared spectroscopy and in vitro drug release of the prepared material, as well as analyzed the morphology of the nanofiber membrane with a scanning electron microscope. In the wound healing experiment, the wound healing rate of APP on the 15th day was 96.67%, and it demonstrated excellent antibacterial activity by the disc diffusion method, showing superior antibacterial activity against Gram-negative bacteria. The skin defect model on the back of mice showed that APP nanofibers significantly induced granulation tissue growth, collagen deposition and epithelial tissue remodeling. Current research shows that the prepared composite nanofibers can quickly stop bleeding and can effectively promote wound healing.

Flow chart for the preparation of “sandwich” nanofiber membranes.     

Antibacterial properties of electrospun Ti3C2Tz (MXene)/chitosan nanofibers

Electrospun natural polymeric bandages are highly desirable due to their low-cost, biodegradability, non-toxicity and antimicrobial properties. Functionalization of these nanofibrous mats with two-dimensional nanomaterials is an attractive strategy to enhance the antibacterial effects. Herein, we demonstrate an electrospinning process to produce encapsulated delaminated Ti₃C₂T_z (MXene) flakes within chitosan nanofibers for passive antibacterial wound dressing applications. In vitro antibacterial studies were performed on crosslinked Ti₃C₂T_z/chitosan composite fibers against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) – demonstrating a 95% and 62% reduction in colony forming units, respectively, following 4 h of treatment with the 0.75 wt% Ti₃C₂T_z – loaded nanofibers. Cytotoxicity studies to determine biocompatibility of the nanofibers indicated the antibacterial MXene/chitosan nanofibers are non-toxic. The incorporation of Ti₃C₂T_z single flakes on fiber morphology was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy equipped with an energy-dispersive detector (TEM-EDS). Our results suggest that the electrospun Ti₃C₂T_z/chitosan nanofibers are a promising candidate material in wound healing applications.

Electrospun natural polymeric bandages are highly desirable due to their low-cost, biodegradability, non-toxicity and antimicrobial properties.     

Pullulan nanofibers containing the antimicrobial palindromic peptide LfcinB (21–25)Pal obtained via electrospinning

Electrospinning technology is useful for making ultrafine drug-eluting fibers for the clinical treatment of wounds. We show the incorporation of an antimicrobial LfcinB-derived peptide into Pullulan nanofibers. The palindromic peptide LfcinB (21–25)_Pal: RWQWRWQWR was synthesized, purified, and characterized by means of the RP-HPLC and MALDI-TOF MS methods. The peptide''s antibacterial activity against the E. coli ATCC 25922 strain was evaluated, and the peptide LfcinB (20–25)_Pal exhibited significant antibacterial activity. Nanofibers were obtained by electrospinning a Pullulan or Pullulan-LfcinB (21–25)_Pal solution. The obtained nanofibers were characterized via microscopy (AFM and SEM) and RP-HPLC chromatography. The peptide incorporation efficiency was 31%. The Pullulan-LfcinB (21–25)_Pal nanofibers were soluble in water, and the peptide was liberated immediately. The Pullulan-LfcinB (21–25)_Pal nanofibers exhibited the same antibacterial activity against E. coli strain as the free peptide LfcinB (21–25)_Pal. The results suggest that Pullulan-LfcinB (21–25)_Pal nanofibers could be considered for designing and developing antibacterial wound dressings.

Pullulan nanofibers containing antimicrobial peptide derived from LfcinB an option as biomaterial for wound dressings.     

Improved uniaxial dielectric properties in aligned diisopropylammonium bromide (DIPAB) doped poly(vinylidene difluoride) (PVDF) nanofibers

Diisopropylammonium bromide (DIPAB) doped poly(vinylidene difluoride) (PVDF) nanofibers (5, 10 and 24 wt% DIPAB doping) with improved and tunable dielectric properties were synthesised via electrospinning. DIPAB nanoparticles were grown in situ during the nanofiber formation. X-Ray diffraction (XRD) patterns and Fourier transform infrared spectroscopy (FTIR) proved that electrospinning of DIPAB doped PVDF solutions led to the formation of a highly electro-active β-phase in the nanofibers. Electrospinning in the presence of DIPAB inside PVDF led to very well aligned nanofibers with preferred (001) orientation that further enhanced the effective dipole moments in the nanofiber structures. The dielectric properties of the composite nanofibers were significantly enhanced due to the improved orientation, ionic and interfacial polarisation upon the applied electrospinning process, ionic nature of DIPAB and the interface between the PVDF nanofibers and equally dispersed DIPAB nanoparticles inside them, respectively. The relative dielectric constant of the PVDF nanofibers was improved from 8.5 to 102.5 when nanofibers were doped with 5% of DIPAB. Incorporating DIPAB in PVDF nanofibers has been shown to be an effective way to improve the structural and dielectric properties of PVDF.

Diisopropylammonium bromide (DIPAB) doped poly(vinylidene difluoride) (PVDF) nanofibers (5, 10 and 24 wt% DIPAB doping) with improved and tunable dielectric properties were synthesised via electrospinning.     

New surgical meshes with patterned nanofiber mats

Abdominal wall hernia repair is one of the most common general surgeries nowadays. Surgical meshes used in hernia repair indeed improved the outcomes, but complications like chronic pain or hernia recurrence partly caused by mechanical mismatch cannot be ignored. This work designed six warp-knitted polypropylene (PP) meshes and found the properties of surgical meshes could be improved to better mimic the performances of human abdominal wall by designing meshes with appropriate textile structures. Poly-caprolactone was electrospun onto newly designed PP meshes and formed a thin layer of patterned nanofiber mat. The pattern of nanofiber mats was affected by the structure of meshes. Diverse nanofiber morphology (straight aligned, straight random or spiral random pattern) and fiber diameters (50–70 nm ultra-thin nanofibers or from 330 nm to 700 nm nanofibers) were observed in different regions of a single patterned nanofiber scaffold. The addition of electrospinning nanofibers enhanced cell adherence and proliferation as compared with naked PP meshes. Cell actin filaments spread along the nanofibers and formed a morphology exactly similar with the patterned mats on day 7. Furthermore, cells on thin and aligned patterned nanofibers showed much more elongation and better orientation than that of the spiral random fibers, suggesting that cell morphology can be altered by changing the patterns of scaffolds. This study helps us in further understanding the properties of hernia repair meshes with their textile structures and the biological interactions of cells with different substrates in order to develop new biomedical scaffolds with desired properties.

Newly designed warp-knitted meshes with different textile parameters and the interactions between cell and patterned nanofiber mats and different meshes.     

Quercetin-gold nanorods incorporated into nanofibers: development,optimization and cytotoxicity

Herein, a polymeric nanofiber scaffold loaded with Quercetin (Quer)–gold nanorods (GNR) was developed and characterized. Several parameters related to loading Quer into GNR, incorporating the GNR-Quer into polymeric solutions, and fabricating the nanofibers by electrospinning were optimized. GNR-Quer loaded into a polymeric mixture of poly(lactic-co-glycolic acid) (PLGA) (21%) and poloxamer 407 (23%) has produced intact GNR-Quer-nanofibers with enhanced physical and mechanical properties. GNR-Quer-nanofibers demonstrated a slow pattern of Quer release over time compared to nanofibers free of GNR-Quer. Dynamic mechanical thermal analysis (DMTA) revealed enhanced uniformity and homogeneity of the GNR-Quer-nanofibers. GNR-Quer-nanofibers demonstrated a high ability to retain water upon incubation in phosphate buffer saline (PBS) for 24 h compared to nanofibers free of GNR-Quer. A cellular toxicity study indicated that the average cellular viability of human dermal fibroblasts was 76% after 24 h of exposure to the nanofibers containing a low concentration of GNR-Quer.

Incorporating GNR-Quer into a mixture of 21% PLGA LMWT and 23% poloxamer 407 produced smooth, intact and uniform electrospun nanofibers with enhanced mechanical properties and hydration potential.     

Blends of neem oil based polyesteramide as nanofiber mats to control Culicidae

Mosquitoes act as vectors for several disease-causing microorganisms and pose a threat to mankind by transmitting various diseases. There are different conventional methods to repel or kill these mosquitoes for avoiding susceptibility against infections. However, to overcome the difficulties with conventional methods, new advanced materials are being studied. For the first time, we report developing a nanofiber mat with a controlled release of insecticide to repel or detain the mosquitoes. Briefly, various blend compositions were prepared by manipulating the ratio of neem oil-based polyesteramide (PEA) and polycaprolactone (PCL) immobilized with insecticide, transfluthrin (Tf). The blend solutions were electrospun to get non-woven nanofiber mats, and these nanomaterials were characterized by various spectroscopic techniques to understand their physicochemical properties. The surface morphology was analyzed using environmental scanning electron microscopy (E-SEM), and the diameter of the nanofibers was in the range of 200 to 450 nm. Further, thermal and mechanical properties were evaluated to understand the stability of nanofiber mats. In vitro drug release studies of nanofiber mat PPT-1335 showed controlled and sustained release of Tf, with ∼35% of Tf released in 24 h. However, a film of the same composition (PPT-1335) showed ∼5% of Tf release within 24 h. Moreover, in vivo bio-efficacy studies suggested the mortality of mosquitoes was about 50% with PP-133, which was further increased to 100% within 12 h in the presence of Tf (PPT-1335). However, 60% mortality of mosquitoes was observed with the film of PPT-1335. Hence, the nanofiber mat showed better efficacy against mosquitoes as compared to the film of the same composition. The degradation studies under various conditions revealed biocompatibility of the developed nanofiber mats with the ecosystem.

Electrospun nanofiber mats immobilized with transfluthrin to control mosquitoes.     

Anti microbial corrosion properties of electrospun cellulose acetate nanofibers containing biogenic silver nanoparticles for copper coatings

Nanofibers with inorganic nanoparticles are novel hybrid nanocomposites that have great potential in various areas. In the present study, cellulose acetate nanofibers (CA-Nf) loaded with biogenic silver nanoparticles were prepared and characterized. In situ synthesis of silver nanoparticles was accomplished using a bacteria free solution as a reducing agent. Nanofibers incorporated with silver nanoparticles were fabricated using the electrospinning technique. Upright microscopy and SEM micrographs depicted that the CA-Nf coatings consist of dense and compact entangled nanofibers that completely cover the copper surface. Corrosion measurements were performed by potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS) techniques on the bare copper and CA-Nf and CA-Nf_5% AgNp coated copper surfaces in artificial seawater (ASW) and Escherichia coli ATCC 13883 inoculated solutions. Weight loss and electrochemical corrosion test results revealed that the CA-Nf-coated copper had greater corrosion resistance than bare copper. The additional electrospun CA-Nf_5% AgNp coating also had greater antibacterial behavior toward model biofilm bacterium Pseudomonas aeruginosa than uncoated copper specimens. Therefore, this nanofiber with AgNps was demonstrated as an efficient anticorrosive material in both corrosive and biocorrosive marine solutions.

Nanofibers with inorganic nanoparticles are novel hybrid nanocomposites that have great potential in various areas.     

An amperometric glucose biosensor based on PEDOT nanofibers

Here we present a simple, low cost approach for the production of PEDOT nanofiber biosensors using simple techniques. Firstly, nanofibers of PEDOT were produced by the chemical vapor polymerization of EDOT on FeCl₃ containing electrospun PAN nanofiber mats. The nanofibers were characterized by SEM, FTIR, CV and conductivity studies, which indicated the formation of homogeneous, porous, electroactive PEDOT nanofibers. The fabrication of biosensors was achieved through the loading of various amounts of GOx on the nanofibers. To uncover their capability, the biosensors were operated under both hydrogen peroxide production and oxygen consumption conditions. For each biosensor current response versus glucose concentration calibration curves were plotted. The sensitivity, linear range, LOD, K_m and I_max values of the biosensors were determined and the stabilities of all the sensors were investigated. The biosensor operating at 0.6 V revealed a lower LOD with a wider linear range, higher stability, good sensitivity and selectivity. For example, the PEDOT-NFs/GOx-3 nanofiber biosensor showed good sensitivity (74.22 μA mM⁻¹ cm⁻²) and LOD (2.9 μM) with a response time of 2–3 s without any interference effects. The PEDOT-NFs/GOx-2 biosensor operating at −0.6 V exhibited extreme sensitivity of 272.58 μA mM⁻¹ cm⁻². Our studies have shown that having good sensitivity, LOD and stability makes these interference-free, easy to construct sensors viable candidates for commercialization.

A low cost, robust approach for the production of glucose biosensors was achieved via simple electrospinning and chemical vapor polymerization techniques.     

Fabrication of bio-based polyurethane nanofibers incorporated with a triclosan/cyclodextrin complex for antibacterial applications

A hybrid polyol consisting of a polycaprolactone diol/castor oil mixture was used to synthesize a biopolyurethane (BPU) that has a dendritic point but is soluble in organic solvents. The chemical structure of the obtained BPU was determined using Fourier transform infrared (FT-IR) spectroscopy and proton nuclear magnetic resonance spectroscopy. The mechanical properties of the electrospun BPU nanofiber were confirmed using a universal testing machine. To enhance the solubility of triclosan (TR), TR–cyclodextrin (CD) complexes were prepared. αCD, βCD, and γCD were used to study the formation of the TR–CD complexes using a coprecipitation technique. The results showed that TR did not form a complex with αCD, whereas it forms complexes partially with βCD and completely with γCD. These findings are supported by FT-IR, differential scanning calorimetry, and X-ray diffraction analyses. The electrospun BPU/TR–CD nanofibers were investigated in terms of morphology, releasing behavior, and antibacterial tests. The BPU/TR–γCD nanofiber shows better antibacterial activity than the others. The results obtained in this study are expected to broaden the range of biobased polyurethane applications where antibacterial properties are required.

Bio-polyurethane nanofibers containing triclosan–cyclodextrin complexes to enhance antibacterial properties were prepared using an electrospinning method.     

Recent update on electrospinning and electrospun nanofibers: current trends and their applications

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made in techniques for creating electro-spun and non-electro-spun nanofibers. Nanofibers were the center of attention for industries and researchers due to their simplicity in manufacture and setup. The review discusses a thorough overview of both electrospinning and non-electrospinning processes, including their setup, fabrication process, components, and applications. The review starts with an overview of the field of nanotechnology, the background of electrospinning, the surge in demand for nanofiber production, the materials needed to make nanofibers, and the critical process variables that determine the characteristics of nanofibers. Additionally, the diverse applications of electrospun nanofibers, such as smart mats, catalytic supports, filtration membranes, energy storage/heritage components, electrical devices (batteries), and biomedical scaffolds, are then covered. Further, the review concentrates on the most recent and pertinent developments in nanofibers that are connected to the use of nanofibers, focusing on the most illustrative cases. Finally, challenges and their possible solutions, marketing, and the future prospects of nanofiber development are discussed.

Electrospinning is a versatile and viable technique for generating ultrathin fibers.     

Stable and sensitive amino-functionalized graphene/polyaniline nanofiber composites for room-temperature carbon dioxide sensing

This article describes the preparation and characterization of amino-functionalized graphene (AmG)/polyaniline (PANI)/poly(methyl methacrylate) (PMMA) nanofiber mats along with the efficiency of these nanofiber composites as a new material for sensing carbon dioxide (CO₂) gas. The surfaces of the PMMA nanofibers were treated at room temperature by ultraviolet (UV) radiation. AmG/PANI was then deposited on the surfaces of the PMMA nanofibers via chemical oxidative polymerization. It was concluded that UV radiation reduced the hydrophobicity of the PMMA surface through introducing oxidized groups onto the surface. The electrical response of the gas sensor based on the composite nanofibers was investigated at room temperature using various concentrations of CO₂ gas. Compared to the PANI/PMMA nanofibers, the AmG/PANI nanofiber composites displayed a better electrical resistance response to CO₂ at room temperature; the AmG/PANI nanofiber composites exhibited higher sensitivity and faster response times under the same conditions.

This article describes the preparation and characterization of amino-functionalized graphene (AmG)/polyaniline (PANI)/poly(methyl methacrylate) (PMMA) nanofiber mats along with the efficiency of these nanofiber composites as a new material for sensing carbon dioxide (CO₂) gas.     

High-water-absorbing calcium alginate fibrous scaffold fabricated by microfluidic spinning for use in chronic wound dressings

More and more water-absorbing wound dressings have been studied since moist wound-healing treatment can effectively promote the healing of wounds. In this work, we introduce a novel method to produce improved wound dressings with high-water-absorbance. A high-water-absorbing calcium alginate (Ca-Alg) fibrous scaffold was fabricated simply by microfluidic spinning and centrifugal reprocessing. The structure and physical properties of the scaffold were characterized, and its water-absorbing, cytotoxicity properties and other applicability to wound dressings were comprehensively evaluated. Our results indicate that this material possesses high water-absorbing properties, is biocompatible, and has a 3D structure that mimics the extracellular matrix, while Ca-Alg fibers loaded with silver nanoparticles (AgNPs) exhibit broad-spectrum antibacterial activities; these properties meet the requirements for promoting the healing of chronic wounds and are widely applicable to wound dressings.

More and more water-absorbing wound dressings have been studied since moist wound-healing treatment can effectively promote the healing of wounds.     

Naproxen release behaviour from graphene oxide/cellulose acetate composite nanofibers

The present study investigated the effect of graphene oxide in cellulose acetate-based composite nanofibers on the transdermal delivery of naproxen. The composite nanofibers were successfully produced via the electrospinning process by directly mixing cellulose acetate, graphene oxide, and naproxen solution with varied compositions. The formation of the nanofibers was confirmed by electron microscopy and other characterization techniques to prove the existence of graphene oxide and naproxen itself. Surprisingly, graphene oxide encourages the production of nanofibers with smaller average diameter, higher conductivity, higher mechanical strength, and higher naproxen release from the cellulose acetate nanofibers. Once combined with naproxen, the composite nanofiber exhibited antibacterial activity with an inhibitory zone of 9.15 mm. The cytotoxicity evaluation also showed that the addition of naproxen increased the death of HeLa cells with a CC₅₀ of up to 29.33 μg mL⁻¹. The kinetic model of naproxen release follows the Korsmeyer–Peppas and Higuchi models with acceleration at neutral pH. These results are promising for further applications for wound healing purposes.

The present study investigated the effect of graphene oxide in cellulose acetate-based composite nanofibers on the transdermal delivery of naproxen.     

Fabrication of a polyvinylidene fluoride cactus-like nanofiber through one-step electrospinning

Surface modification of fibers has attracted significant attention in different areas and applications. In this work, polyvinylidene fluoride (PVDF) cactus-like nanofibers were directly produced via electrospinning at a high relative humidity (RH) of 62%. The formation mechanism of the cactus structure was demonstrated. The effects of the RH on the fabrication of the cactus structure, crystalline phases, mechanical properties, hydrophobicity, and piezoelectric properties of the PVDF nanofibers were investigated. The results showed that the cactus-like nanofibers have a high crystallinity (ΔX_c), and an outstanding water contact angle (WCA), as well as good electrical outputs. We believe that the PVDF cactus structure can be used in many applications such as energy harvesting and self-cleaning surfaces.

A novel PVDF cactus-like nanofiber was directly electrospun. The mechanism of formation, properties, and possible applications were demonstrated.     

Shape-controllable nanofibrous membranes with well-aligned fibers and robust mechanical properties for PM2.5 capture

In this study, design and fabrication of novel shape-controllable and aligned nanofibrous membranes with self-cleaning and robust mechanical properties is presented. Smooth and uniform nanofibers can be fabricated by blending polyamide 66 (PA66) and poly (vinyl butyral) (PVB) with a mass ratio of 6/4 during electrospinning. Subsequently, the prepared nanofibrous membranes were placed in a vacuum drying oven at a given temperature (90 °C) for heat treatment, and the morphology of the composite nanofibers was controlled by an external tensile force. It was found that the treatment temperature and external tensile force greatly affected the pore structures and orientation of the nanofiber membranes. In addition, the hydrophobicity, pore structure and mechanical properties of well-aligned nanofibrous membranes are better than those of non heat-treatment nanofibers. Moreover, the PA66/PVB nanofibrous membranes are used as air filters, and show an excellent removal efficiency of up to 99.99% for PM_2.5.

A schematic of the preparation of PA66/PVB composite nanofibrous membranes by a facile method of electrospinning and heat-induced alignment.     

Preparation and characterization of antibacterial dopamine-functionalized reduced graphene oxide/PLLA composite nanofibers

Electrospun poly(l)-lactide (PLLA) ultrafine fibers are a biodegradable and biocompatible scaffold, widely used in tissue engineering applications. Unfortunately, these scaffolds have some limitations related to the absence of bioactivity and antibacterial capacity. In this study, dopamine-functionalized reduced graphene oxide (rGO)/PLLA composite nanofibers were fabricated via electrospinning. The morphology and the physicochemical and biological properties of the composite nanofibers were investigated. The results indicate that incorporating rGO improves the hydrophilic, mechanical, and biocompatibility properties of PLLA nanofibers. Tetracycline hydrochloride (TC)-loaded rGO/PLLA composite nanofibers showed better controlled drug release profiles compared to GO/PLLA and PLLA nanofibrous scaffolds. Drug-loaded nanofibrous scaffolds showed significantly improved antibacterial activity against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Additionally, rGO/PLLA composite nanofibers exhibited enhanced cytocompatibility. Thus, it can be concluded that rGO/PLLA composite nanofibers allow the development of multifunctional scaffolds for use in biomedical applications.

Antibacterial dopamine-functionalized reduced graphene oxide (rGO)/PLLA composite nanofibers for biomedical applications.