Core-shell Electrospun Nanofibers Research Articles

Levofloxacin loaded poly (ethylene oxide)-chitosan/quercetin loaded poly (D,L-lactide-co-glycolide) core-shell electrospun nanofibers for burn wound healing.

This study developed a new burn wound dressing based on core-shell nanofibers that co-deliver antibiotic and antioxidant drugs. For this purpose, poly(ethylene oxide) (PEO)-chitosan (CS)/poly(D,L-lactide-co-glycolide) (PLGA) core-shell nanofibers were fabricated through co-axial electrospinning technique. Antibiotic levofloxacin (LEV) and antioxidant quercetin (QS) were incorporated into the core and shell parts of PEO-CS/PLGA nanofibers, respectively. The drugs could bond to the polymer chains through hydrogen bonding, leading to their steady release for 168h. An in vitro drug release study showed a burst effect followed by sustained release of LEV and QS from the nanofibers due to the Fickian diffusion. The NIH 3T3 fibroblast cell viability of the drug loaded core-shell nanofibers was comparable to that in the control (tissue culture polystyrene) implying biocompatibility of the nanofibers and their cell supportive role. However, there was no significant difference in cell viability between the drug loaded and drug free core-shell nanofibers. According to in vivo experiments, PEO-CS-LEV/PLGA-QS core-shell nanofibers could accelerate the healing process of a burn wound compared to a sterile gauze. Thanks to the synergistic therapeutic effect of LEV and QS, a significantly higher wound closure rate was recorded for the drug loaded core-shell nanofibrous dressing than the drug free nanofibers and control. Conclusively, PEO-CS-LEV/PLGA-QS core-shell nanofibers were shown to be a promising wound healing material that could drive the healing cascade through local co-delivery of LEV and QS to burn wounds.

Silver Nanoparticles In Situ Synthesized and Incorporated in Uniaxial and Core-Shell Electrospun Nanofibers to Inhibit Coronavirus.

In the present study, we sought to develop materials applicable to personal and collective protection equipment to mitigate SARS-CoV-2. For this purpose, AgNPs were synthesized and stabilized into electrospinning nanofiber matrices (NMs) consisting of poly(vinyl alcohol) (PVA), chitosan (CHT), and poly-ε-caprolactone (PCL). Uniaxial nanofibers of PVA and PVA/CHT were developed, as well as coaxial nanofibers of PCL[PVA/CHT], in which the PCL works as a shell and the blend as a core. A crucial aspect of the present study is the in situ synthesis of AgNPs using PVA as a reducing and stabilizing agent. This process presents few steps, no additional toxic reducing agents, and avoids the postloading of drugs or the posttreatment of NM use. In general, the in situ synthesized AgNPs had an average size of 11.6 nm, and the incorporated nanofibers had a diameter in the range of 300 nm, with high uniformity and low polydispersity. The NM's spectroscopic, thermal, and mechanical properties were appropriate for the intended application. Uniaxial (PVA/AgNPs and PVA/CHT/AgNPs) and coaxial (PCL[PVA/CHT/AgNPs]) NMs presented virucidal activity (log's reduction ≥ 5) against mouse hepatitis virus (MHV-3) genus Betacoronavirus strains. In addition to that, the NMs did not present cytotoxicity against fibroblast cells (L929 ATCC® CCL-1TM lineage).

Irisin-loaded electrospun core-shell nanofibers as calvarial periosteum accelerate vascularized bone regeneration by activating the mitochondrial SIRT3 pathway.

The scarcity of native periosteum poses a significant clinical barrier in the repair of critical-sized bone defects. The challenge of enhancing regenerative potential in bone healing is further compounded by oxidative stress at the fracture site. However, the introduction of artificial periosteum has demonstrated its ability to promote bone regeneration through the provision of appropriate mechanical support and controlled release of pro-osteogenic factors. In this study, a poly (l-lactic acid) (PLLA)/hyaluronic acid (HA)-based nanofibrous membrane was fabricated using the coaxial electrospinning technique. The incorporation of irisin into the core-shell structure of PLLA/HA nanofibers (PLLA/HA@Irisin) achieved its sustained release. In vitro experiments demonstrated that the PLLA/HA@Irisin membranes exhibited favorable biocompatibility. The osteogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs) was improved by PLLA/HA@Irisin, as evidenced by a significant increase in alkaline phosphatase activity and matrix mineralization. Mechanistically, PLLA/HA@Irisin significantly enhanced the mitochondrial function of BMMSCs via the activation of the sirtuin 3 antioxidant pathway. To assess the therapeutic effectiveness, PLLA/HA@Irisin membranes were implanted in situ into critical-sized calvarial defects in rats. The results at 4 and 8 weeks post-surgery indicated that the implantation of PLLA/HA@Irisin exhibited superior efficacy in promoting vascularized bone formation, as demonstrated by the enhancement of bone matrix synthesis and the development of new blood vessels. The results of our study indicate that the electrospun PLLA/HA@Irisin nanofibers possess characteristics of a biomimetic periosteum, showing potential for effectively treating critical-sized bone defects by improving the mitochondrial function and maintaining redox homeostasis of BMMSCs.

Zinc ions and ciprofloxacin-encapsulated chitosan/poly(ɛ-caprolactone) composite nanofibers promote wound healing via enhanced antibacterial and immunomodulatory

Antibacterial and anti-inflammatory nanofibrous membranes have attracted extensive attention, especially for the cutaneous wound treatment. In this study, zinc ions and ciprofloxacin-encapsulated chitosan/poly(ɛ-caprolactone) (CS/PCL) electrospun core-shell nanofibers were prepared by employing zinc ions-coordinated chitosan as the shell, and ciprofloxacin-functionalized PCL as the core. The morphology and core-shell structure of the as-prepared composite nanofibers were examined by SEM and TEM, respectively. The physical structure and mechanical property of the electrospun membrane were explored by FTIR, swelling, porosity and tensile test. Tensile strength of the zinc ions-coordinated CS/PCL composite nanofibers was enhanced to ca. 16 MPa. Meanwhile, the composite nanofibers can rapidly release of ciprofloxacin during 11 days and effectively suppress above 98 % of S. aureus proliferation. Moreover, the composite nanofibers exhibited excellent guide cell alignment and cyto-activity, as well as significantly down-regulated the inflammation factors, IL-6 and TNF-α in vitro. Animal experiments in vivo showed that the zinc ions-coordinated CS/PCL membrane by means of the synergistic effect of ciprofloxacin and active zinc ions, could significantly alleviate macrophage infiltration, promote collagen deposition and accelerate the healing process of wounds.

Fabrication of porous cobalt oxide/carbon nanopolks on electrospun hollow carbon nanofibers for microextraction by packed sorbent of parabens from human blood

In this work, electrospinning and hydrothermal methods were employed to synthesize an innovative 3D Co3O4/C@HCNFs nanocomposite as the sorbent. It was then used in a packed sorbent microextraction system for parabens analysis in human blood samples, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The coaxial electrospun core-shell nanofibers mat was stabilized and carbonized to produce the hollow carbon nanofibers (HCNFs) substrate. A coating of cobalt carbonate hydroxide nanopolks was then grown on the HCNFs through hydrothermal synthesis. Ultimately, some of the nanopolks were converted to ZIF-67 by pouring the mat into a warm solution of 2-methyl imidazole and heat-treated into porous Co3O4/C afterward. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses were used to characterize the produced nanocomposite. The effective parameters of the adsorption and desorption steps were optimized by a central composite design. The figures of merit were evaluated under optimal conditions. The linear range of parabens was obtained between 0.5–500.0 ng ml−1 with R2 ≥ 0.9980. The detection limits of the method were between 0.1 and 0.2 ng ml−1. The intra-day and inter-day precisions were less than 4.3%. Relative recoveries between 92.0% and 109.3% were achieved. The findings demonstrated the eligible performance of the method.

Direct magnetoelectric and magnetodielectric studies of electrospun Ba2Ni2Fe12O22–Pb(Zr0.52Ti0.48)O3 core–shell nanofibers

This article reports the synthesis of barium nickel hexaferrite-lead zirconium titanate (Ba2Ni2Fe12O22-Pb(Zr0.52Ti0.48)O3) core-shell nanofibers through sol-gel electrospinning method. Direct magnetoelectric and magnetodielectric coupling studies were performed on the synthesized electrospun core-shell nanofibers. The structure, functional, morphological, magnetic, dielectric, leakage current, and ferroelectric properties were also analyzed. X-ray diffraction studies revealed the hexagonal crystal structure of the core and the tetragonal structure of the shell. The Fourier transform infrared spectroscopy analysis showed the fundamental functional groups present in the nanofibers. Scanning electron microscopy studies showed that the diameter of the nanofibers was 404 nm, and elemental analysis by energy-dispersive X-ray spectroscopy showed the stoichiometric formation of Ba2Ni2Fe12O22 and Pb(Zr0.52Ti0.48)O3 in the composite. Microstructure studies using a transmission electron microscope revealed the formation of core-shell nanofibers with a clear interface between the magnetic Ba2Ni2Fe12O22 (BNFO) core and the ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) shell. Selected-area electron diffraction analysis showed the Ba2Ni2Fe12O22 and Pb(Zr0.52Ti0.48)O3 phases to be highly crystalline. At room temperature, the synthesized nanofibers exhibited well-defined ferroelectric and magnetic hysteresis loops. Dielectric and leakage current studies were performed. Direct magnetoelectric and magnetodielectric studies were also performed to study the cross-coupling between the ferroic orders of the nanofiber. Moreover, using Landau’s energy expression, the type of magnetoelectric coupling was proved to be biquadratic. The enhanced magnetoelectric behavior of the Ba2Ni2Fe12O22–Pb(Zr0.52Ti0.48)O3 core–shell nanofiber confirms that the nanofiber is a potential candidate for high-performing magnetic field sensors, magnetically tuned capacitors, multimedia transducers, and spintronic devices.

Novel polycaprolactone (PCL)-type I collagen core-shell electrospun nanofibers for wound healing applications.

Type I collagen (Col_1) is one of the main proteins present in the skin extracellular matrix, serving as support for skin regeneration and maturation in its granulation stage. Electrospun materials have been intensively studied as the next generation of skin wound dressing mainly due to their high surface area and fibrous porosity. However, the electrospinning of collagen-based solutions causes degradation of its structure. In this work, a coaxial electrospinning process was proposed to overcome this limitation. The production of mats of polycaprolactone (PCL)-Col_1/PVA (collagen/poly(vinyl alcohol)) composed of core-shell nanofibers was investigated. PCL solution was used as the core solution, while Col_1/PVA was used as the shell solution. PVA was used to improve the processability of collagen, while PCL was employed to improve the mechanical properties and morphology of Col_1/PVA fibers. The morphology and the cytotoxicity of the fibers were highly dependent on the processing parameters. Defect-free core-shell nanofibers were obtained with a shell/core flow rates ratio=4, flight distance of 12 cm, and an applied voltage of 16 kV. Using this strategy, the triple helix structure characteristic of the collagen molecule was preserved. Moreover, the common post-processing of solvent removal could be suppressed, simplifying the manufacturing processing of these biomaterials. The nanostructured mats showed no cytotoxicity, high liquid absorption, structural stability, hydrophilic character, and collagen release capacity, making them a potential novel dressing for skin damage regeneration, in special in the case of chronic wounds treatment, in which exogenous collagen delivery is necessary.

Natural protein-based electrospun nanofibers for advanced healthcare applications: progress and challenges.

Electrospinning is an electrostatic fiber fabrication technique that operates by the application of a strong electric field on polymer solution or melts. It is used to fabricate fibers whose size lies in the range of few microns to the nanometer range. Historic development of electrospinning has evinced attention due to its outstanding attributes such as small diameter, excellent pore inter-connectivity, high porosity, and high surface-to-volume ratio. This review aims to highlight the theory behind electrospinning and the machine setup with a detailed discussion about the processing parameters. It discusses the latest innovations in natural protein-based electrospun nanofibers for health care applications. Various plant- and animal-based proteins have been discussed with detailed sample preparation and corresponding processing parameters. The usage of these electrospun nanofibers in regenerative medicine and drug delivery has also been discussed. Some technical innovations in electrospinning techniques such as emulsion electrospinning and coaxial electrospinning have been highlighted. Coaxial electrospun core-shell nanofibers have the potential to be utilized as an advanced nano-architecture for sustained release targeted delivery as well as for regenerative medicine. Healthcare applications of nanofibers formed via emulsion and coaxial electrospinning have been discussed briefly. Electrospun nanofibers have still much scope for commercialization on large scale. Some of the available wound-dressing materials have been discussed in brief.

Electrospun core-shell nanofibers with encapsulated enamel matrix derivative for guided periodontal tissue regeneration.

The osteogenic effect of a composite electrospun core-shell nanofiber membrane encapsulated with Emdogain® (EMD) was evaluated. The membrane was developed through coaxial electrospinning using polycaprolactone as the shell and polyethylene glycol as the core. The effects of the membrane on the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) were examined using Alizarin Red S staining and qRT-PCR. Characterization of the nanofiber membrane demonstrated core-shell morphology with a mean diameter of ~1 µm. Examination of the release of fluorescein isothiocyanate-conjugated bovine serum albumin (FITC-BSA) from core-shell nanofibers over a 22-day period showed improved release profile of encapsulated proteins as compared to solid nanofibers. When cultured on EMD-containing core-shell nanofibers, PDLSCs showed significantly improved osteogenic differentiation with increased Alizarin Red S staining and enhanced osteogenic gene expression, namely OCN, RUNX2, ALP, and OPN. Core-shell nanofiber membranes may improve outcomes in periodontal regenerative therapy through simultaneous mechanical barrier and controlled drug delivery function.

Frustrated Crystallization behavior of Poly(ethylene oxide) in Electrospun Core-Shell Nanofibers and Beads

Frustrated Crystallization behavior of Poly(ethylene oxide) in Electrospun Core-Shell Nanofibers and Beads

Antimicrobial core–shell electrospun nanofibers containing Ajwain essential oil for accelerating infected wound healing

Treatment of skin injuries is still facing major challenges, such as chronicity and infections, particularly those caused by multi-drug resistance pathogens. An effective treatment of such wounds should accelerate the wound healing process while preventing bacterial contamination. Here, a novel core–shell nanofiber mat was fabricated comprising gelatin/polyvinyl alcohol (as a core) and aloe vera/arabinose/polyvinylpyrrolidone (as a shell) for accelerating the healing process of bacteria-infected wounds. Trachyspermum Ammi (Ajwain) essential oil (EO), as a potent and natural antimicrobial agent against microorganisms, was incorporated into the core of nanofiber mats using coaxial electrospinning. The microscopy images demonstrated the successful fabrication of the core–shell structure with a uniform fiber size of 564 ± 106.35 nm. Moreover, Ajwain EO-loaded nanofiber mat (core–shell/EO) provided excellent antimicrobial activity and antioxidant ability. The in vitro and ex vivo release of Ajwain EO from the fabricated nanofiber mat corroborated a prolonged release profile. Furthermore, in vivo antibacterial activity, wound closure, and histomorphological examinations showed the high efficacy of the core–shell/EO mat in the treatment of Staphylococcus aureus-infected full-thickness rat wounds compared to standard control treatment with a gauze. Overall, these results represent the core–shell/EO mat's potential as a newly developed wound dressing for bacteria-infected full-thickness skin injuries.

Self-Healing Coatings Containing Core-Shell Nanofibers with pH-Responsive Performance.

The micro-nanofibers prepared by the electrospinning technique can be used as a good container for loading healing agents. The core-shell electrospun nanofibers with polyacrylonitrile as the outer shell and tannic acid (TA) and tung oil as the core healing agents were synthesized by a coaxial electrospinning method and exhibited pH-sensitive ability. The nanofibers as additives were added to an epoxy resin coating as a self-healing coating. The morphological stability of the electrospun nanofibers were observed by a scanning electron microscope and a transmission electron microscope. Fourier transform infrared spectroscopy and fluorescence microscopy reveal that the successful synthesis and uniform distribution of core-shell fibers. The mechanical properties test revealed that the tensile properties of the coating could be improved by adding nanofibers. The infrared mapping test, energy-dispersive spectrometry, and X-ray photoelectron spectroscopy, which were carried out on the scratched part of the coating, proved the release of the healing agent in the damaged part. TA forms a protective film on the exposed metal surface through molecular adsorption under acidic conditions. Meanwhile, the curing of tung oil can effectively compensate into the microcracks to form a TA protective film, which could improve the self-healing performance. As the tung oil dries and solidifies in the alkaline solution, the cross-linking effect of the molecules is combined to form a tight film and strength the self-healing ability. TA as an acidic healing agent and tung oil as an alkaline healing agent played the role of pH-sensitive products in healing the cracked coating. The self-healing rates of coating immersing in 3.5 wt % acidic NaCl solution and alkaline solution were 81.6 and 71.2%, respectively. The composite coating shows a great pH-sensitive self-healing ability to heal the cracked coating.

Construction of Natural Loofah/Poly(vinylidene fluoride) Core-Shell Electrospun Nanofibers via a Controllable Janus Nozzle for Switchable Oil-Water Separation.

Developing microstructure and multifunctional membranes toward switchable oil-water separation has been highly desired in oily wastewater treatment. Herein, a controllable Janus nozzle was employed to innovatively electrospin natural loofah/poly(vinylidene fluoride) (PVDF) nanofibers with a core-shell structure for gravity-driven water purification. By adjusting flow rates of the PVDF component, a core-shell structure of the composite fibers was obtained caused by the lower viscosity and surface tension of PVDF. In addition, a steady laminar motion of fluids was constructed based on the Reynolds number of flow fields being less than 2300. In order to investigate the formation mechanism of the microstructure, a series of Janus nozzles with different lengths were controlled to study the blending of the two immiscible components. The gravity difference between the two components might cause disturbance of the jet motion, and the PVDF component unidirectionally encapsulated the loofah to form the shell layer. Most importantly, the dry loofah/PVDF membranes could separate oil from an oil-water mixture, while the water-wetted membrane exhibited switchable separation that could separate water from the mixtures because of the hydroxyl groups of the hydrophilic loofah hydrogen-bonding with water molecules and forming a hydration layer. The composite fibers can be applied in water remediation in practice, and the method to produce core-shell structures seems attractive for technological applications involving macroscopic core-shell nano- or microfibers.

Glucantime-loaded electrospun core-shell nanofibers composed of poly(ethylene oxide)/gelatin-poly(vinyl alcohol)/chitosan as dressing for cutaneous leishmaniasis

Leishmaniasis, one of the main concerns of the World Health Organization, is a parasitic disease caused by Leishmania species. The main objective of this study was to prepare a topical drug delivery system that can deliver glucantime to the site of cutaneous Leishmania wounds. Using the electrospinning method, a core-shell nanofibrous mat composed of macromolecules including polyethylene oxide, gelatin, poly (vinyl alcohol) and chitosan was prepared. The prepared nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy, Fourier transform infrared spectroscopy (FT-IR), tensile test and in vitro drug release test. The anti-Leishmania activities of drug-loaded nanofibers against Leishmania promastigotes and its cytotoxicity on fibroblasts were determined respectively by flow-cytometry and indirect MTT methods. Results of morphological studies showed that uniform nanofibers were prepared without any bead with average diameter of 404 nm. The TEM investigation confirmed the core-shell structure of the fibers. The in-vitro drug release assay was executed using Franz diffusion cell, which indicted 84% of glucantime was released during the first 9 h. The results indicated that 4 and 6 cm2 of nanofibers mat were significantly killed promatigotes up to 78%. Moreover, the MTT assay also showed that the fabricated nanofibers do not possess any cytotoxicity towards fibroblast cells.

Highly efficient detection of cancer-derived exosomes using modified core-shell electrospun nanofibers as a capture substrate and antibody immobilized-graphene quantum dots as a signaling agent.

In the past few years graphene quantum dots (GQDs) have been used as a signaling agent for medical diagnosis. They can be modified and labeled with different macromolecules to give them potential to be attached to a specific target. Herein GQDs were labeled with an antibody which is specific for cancer-derived exosomes, isolated from blood serum by using a specialized PCL-gelatin core-shell NFM. This membrane showed excellent sensitivity for isolating exosomes from a complex mixture such as serum, and the GQD-antibody complex detected the isolated exosomes with great sensitivity. The final results allow this method to be considered as one that can be used to quantify the concentration of a desired analyte in a mixture.

Electrospun core-shell nanofibers as an adsorbent for on-line micro-solid phase extraction of monohydroxy derivatives of polycyclic aromatic hydrocarbons from human urine, and their quantitation by LC-MS.

A method is described for automatted on-line micro-solid phase extraction using polydopamine-modified polystyrene/silica electrospun nanofibers as an adsorbent for monohydroxy metabolites of polycyclic aromatic hydrocarbons (OH-PAHs). They were then quantified by liquid chromatography-mass spectrometry. The sorbent has a network structure, high porosity, stability, hydrophilicity and good extraction capacity. Under optimal experimental conditions, the method has (a) wide linear ranges (0.03-25ng·mL-1 for 3-hydroxyphenanthrene and 1-hydroxypyrene; and 0.05-25ng·mL-1 for 2-naphthol), (b) good precision (with relative standard deviations from 2.0 to 12.4%), (c) highenrichment factors (24-112), (d) low limits of detection (2-21pg·mL-1), and (e) acceptable recoveries from spiked samples (79.1 to 108%). The method was successfully applied for the analysis of trace OH-PAHs in urine. Graphical abstractSchematic illustration of online micro-solid phase extraction using polydopamine-modified polystyrene/silica electrospun nanofibers as adsorbent for the enrichment and determination of monohydroxy metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) prior to LC-MS analysis.

PH-sensitive core-shell electrospun nanofibers based on polyvinyl alcohol/polycaprolactone as a potential drug delivery system for the chemotherapy against cervical cancer

pH-sensitive polyvinyl alcohol/polycaprolactone (PVA/PCL) core-shell nanofibers were successfully fabricated by coaxial electrospinning method, in which PVA and PCL formed the core and shell layers, respectively. The core-shell microstructure of the fibers was certified by transmission electron microscopy (TEM). With the change of the feed ratio between PVA and PCL, there was little difference on the surface morphology of the fibers. FT-IR results indicated that there was no chemical interaction between PVA and PCL in the fibers. The as-prepared fibers can be used as a carrier for anticancer agent doxorubicin (DOX), which showed sustained and pH-responsive release of the drug. In addition, the DOX loaded fibers presented excellent performance against cervical cancer Hela cells. Such pH-sensitive nanofibers, which can degrade effectively in either acidic or neutral condition, have great potential for application in biomedical related fields.

Impedimetric aptamer based determination of the tumor marker MUC1 by using electrospun core-shell nanofibers.

An impedimetric single-shot assay is described for the determination of the proteinic breast cancer marker MUC1. The surface of a glassy carbon electrode was modified with core-shell nanofibers, multi-walled carbon nanotubes and gold nanoparticles that were covalently modified with the MUC1-binding aptamer. Detection is based on the change of the resistance of the electrode surface as measured by electrochemical impedance spectroscopy using hexacyanoferrate(II/III) as an electrochemical probe in working potential is 0.25V. Scanning electron microscopy and cyclic voltammetry were also applied to characterize the electrode. The analytical response ranges from 5 to 115nM of MUC1, with a detection limit of 2.7nM. The assay was successfully applied to MUC1 determination in spiked serum samples where it gave satisfactory results. Graphical abstractAn impedimetric nanoprobe for thetumor marker MUC1 is proposed. It is based on use of electrospun honey core-shell nanofibers. The nanoprobe exhibits excellent sensitivity, good stability and alow detection limit.

Single-nozzle Core-shell Electrospun Nanofibers of PVP/Dextran as Drug Delivery System

Ciprofloxacin-loaded poly(vinylpyrrolidinone) (PVP) and dextran sulfate (Dex) (PVP/Dex) nanofibers were prepared using the emulsion electrospinning method. The physical and morphological characteristics of the prepared nanofibers were evaluated by conducting a Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The polymer-polymer and polymer-drug interactions were determined using differential scanning calorimetry (DSC). Moreover, the formation of the core-shell structure was confirmed by transmission electron microscopy (TEM) and confocal laser microscopy. The sustained release behavior was evaluated using ultraviolet-visible (UV-vis) spectroscopy, and its kinetic mechanism was investigated using Korsmeyer-Peppas, Peppas-Sahlin, and Weibull models by a non-linear regression equation. The antibacterial properties were evaluated using the disc diffusion method with respect to several wound gram-positive (Methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Staphylococcus aureus, and Klebsiella pneumoniae) and gram-negative bacteria (Pseudomonas aeruginosa, Salmonella typhimurium, and Proteus vulgaris). In general, the release behavior of Ciprofloxacin from PVP/Dex is controlled by diffusion in the delivery system.

Analysis of long-term optical performance of phosphorescent oxygen sensing polymeric nanofibers

Photostability assessments of polymeric optical oxygen sensors are typically of limited duration (orders of magnitude lower than real application durations), involve irreproducible setups, ignore sensitivity changes and evaluate a limited number of samples. Using custom LED aging bays, continuous photobleaching (>1 month) was used to assess oxygen-sensitive polysulfone-polycaprolactone core-shell electrospun nanofibers with incorporated platinum (II)- or palladium (II)-based porphyrins. Increased [porphyrin] corresponded to greater initial brightness and more rapid photobleaching. Nevertheless, the rapid solvent evaporation characteristic of electrospinning allowed for linear Stern-Volmer plots for solids loading as high as 10 wt%. UV excitation resulted in a greater initial photobleaching rate for both brightness and sensitivity, but these decreases ended after ~1 week; green-aged samples continued to photobleach out to 1000 h. Via straightforward monitoring of brightness, oxygen sensitivity and Stern-Volmer linearity, this long-term photobleaching assessment protocol can be used to screen dozens of polymer sensors for real-life applications.