Core-Sheath Fibers via Single-Nozzle Spinneret Electrospinning of Emulsions and Homogeneous Blend Solutions.

The preparation of core-sheath fibers by electrospinning is a topic of significant interest for producing composite fibers with distinct core and sheath functionalities. Moreover, in core-sheath fibers, low-molecular-weight substances or nanosized inorganic additives can be deposited in a targeted manner within the core or the sheath. Commonly, for obtaining a core-sheath structure, coaxial electrospinning is used.

Electrospun Fibers of Biocompatible and Biodegradable Polyesters, Poly(Ethylene Oxide) and Beeswax with Anti-Bacterial and Anti-Fungal Activities.

Fibrous materials composed of core-sheath fibers from poly(ethylene oxide) (PEO), beeswax (BW) and 5-nitro-8-hydroxyquinoline (NQ) were prepared via the self-organization of PEO and BW during the single-spinneret electrospinning of a homogeneous blend solution of the partners. Additionally, the application of the same approach enabled the preparation of fibrous materials composed of core-double sheath fibers from PEO, poly(L-lactide) (PLA) and NQ or 5-chloro-7-iodo-8-hydroxyquinoline (CQ), as well as from PEO, poly(ε-caprolactone) (PCL) and NQ. The consecutive selective extraction of BW and of the polyester with hexane and tetrahydrofuran, respectively, evidenced that core-double sheath fibers from PEO/polyester/BW/drug consisted of a PEO core, a polyester inner sheath and a BW outer sheath.

Core/Double-Sheath Composite Fibers from Poly(ethylene oxide), Poly(L-lactide) and Beeswax by Single-Spinneret Electrospinning.

The conventional approach for preparation of core-sheath fibers is coaxial electrospinning. Single-spinneret electrospinning of emulsions is a much less common method to obtain core-sheath fibers. Core-sheath structure may be generated by electrospinning of homogeneous blend solutions; however, reports on such cases are still scarce.

Core-Sheath-Like Poly(Ethylene Oxide)/Beeswax Composite Fibers Prepared by Single-Spinneret Electrospinning. Antibacterial, Antifungal, and Antitumor Activities.

Composite fibrous materials are prepared from poly(ethylene oxide) (PEO) and beeswax (BW) by single-spinneret electrospinning using chloroform as a common solvent. The obtained fibers have core-sheath-like structure, as evidenced by the water contact angle values and corroborated by the results on the elemental composition of the fiber's surface determined by X-ray photoelectron spectroscopy (XPS) and by analyses with scanning electron microscopy of fibers before and after selective extraction of PEO or BW. Furthermore, the core-sheath-like structure is proven by transmission electron microscopy.

Photocatalytic self-cleaning poly(L-lactide) materials based on a hybrid between nanosized zinc oxide and expanded graphite or fullerene.

New self-cleaning materials of polymer fibers decorated with a hybrid between nanosized zinc oxide and expanded graphite (EG) or fullerene (C60) were obtained. The new materials were prepared by applying electrospinning in conjunction with electrospraying. Poly(l-lactide) (PLA) was selected as a biocompatible and (bio)degradable polymer carrier.

Poly(L-lactide) and poly(butylene succinate) immiscible blends: from electrospinning to biologically active materials.

For the first time the preparation of defect-free fibers from immiscible blends of high molar mass poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) in the whole range of the polyester weight ratios is shown. Electrospinning using the solvent-nonsolvent approach proved most appropriate. Moreover, electrospinning revealed crucial for the obtaining of PLA/PBS materials maintaining integrity.

Antibacterial fluoroquinolone antibiotic-containing fibrous materials from poly(L-lactide-co-D,L-lactide) prepared by electrospinning.

Microfibrous materials based on poly(l-lactide-co-d,l-lactide) (coPLA) and coPLA/poly(ethylene glycol) (PEG) containing a fluoroquinolone antibiotic: ciprofloxacin hydrochloride (Cipro), levofloxacin hemihydrate (Levo) or moxifloxacin hydrochloride (Moxi) were obtained by electrospinning. The presence of Moxi led to an increase in the conductivity of the coPLA and coPLA/PEG spinning solutions and to the preparation of membranes composed of fibers aligned with the collector rotation direction. The one-step incorporation of the antibiotics in the fibers was confirmed by infrared spectroscopy and fluorescence microscopy.

Antibacterial electrospun poly(ɛ-caprolactone)/ascorbyl palmitate nanofibrous materials.

The one-step incorporation of ascorbyl palmitate (AP), a widely used derivative of vitamin C, into nanofibrous mats of poly(ɛ-caprolactone) (PCL) by electrospinning was demonstrated. The incorporation of AP was attested by IR spectroscopy; the AP content was determined by thermogravimetric analysis (TGA); and the surface composition of the mats: by X-ray photoelectron spectroscopy (XPS). The possibility for deposition of silver nanoparticles onto PCL/AP mats using the ability of AP to reduce silver ions was demonstrated.

Hybrid nanofibrous yarns based on N-carboxyethylchitosan and silver nanoparticles with antibacterial activity prepared by self-bundling electrospinning.

Hybrid nanofibrous materials with antibacterial activity consisting of yarns from N-carboxyethylchitosan (CECh) and poly(ethylene oxide) (PEO) that contain 5 wt% or 10 wt% silver nanoparticles (AgNPs) were prepared. This was achieved by electrospinning using formic acid as a solvent and as a reducing agent for silver ions. AgNO₃ was used as an Ag(+)-containing salt.

Tuning of the surface biological behavior of poly(L-lactide)-based electrospun materials by polyelectrolyte complex formation.

Poly(L-lactide) (PLLA) and poly(L-lactide)/poly(ethylene glycol) (PLLA/PEG) electrospun fibrous materials coated with a polyelectrolyte complex (PEC) were prepared. This was achieved by consecutive deposition of a layer of N-carboxyethylchitosan (CECh) and a layer of a double hydrophilic block copolymer, poly(ethylene oxide)-b-quaternized poly[2-(dimethylamino)ethyl methacrylate] (PEO-b-PDMAEMAQ100), resulting in PEC formation between the two polyelectrolytes on the surface. Noteworthy, to improve the water wettability of the electrospun PLLA fibrous materials, that is, to enable more uniform deposition of the polyelectrolyte partners, water/ethanol mixed solvent was used for preparation of CECh and PEO-b-PDMAEMAQ100 solutions.

Polylactide stereocomplex-based electrospun materials possessing surface with antibacterial and hemostatic properties.

Novel fibrous materials of stereocomplex between high-molecular-weight poly(d- or l-)lactide (HMPDLA or HMPLLA) and diblock copolymers consisting of poly(l- or d-)lactide and poly(N,N-dimethylamino-2-ethyl methacrylate) blocks, respectively (PLLA-block-PDMAEMA or PDLA-block-PDMAEMA), were prepared by solution electrospinning. Fibers with mean diameters ranging from 1400 to 1700 nm were obtained. The stereocomplex formation was evidenced by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses.

Electrospun hybrid nanofibers based on chitosan or N-carboxyethylchitosan and silver nanoparticles.

Hybrid nanofibers from chitosan or N-carboxyethylchitosan (CECh) and silver nanoparticles (AgNPs) were prepared by electrospinning using HCOOH as a solvent. AgNPs were synthesized in situ in the spinning solution. HCOOH slowed down the cross-linking of the polysaccharides with GA enabling the reactive electrospinning in the presence of poly(ethylene oxide) (PEO).

Amphiphilic poly(D- or L-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) block copolymers: controlled synthesis, characterization, and stereocomplex formation.

Novel well-defined amphiphilic poly(D-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PDLA-b-PDMAEMA) and poly(L-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PLLA-b-PDMAEMA) copolymers were obtained. The synthesis strategy consisted of a three-step procedure: (i) controlled ring-opening polymerization (ROP) of (D- or L-)lactide initiated by Al(O(i)Pr)(3), followed by (ii) quantitative conversion of the polylactide (PLA) hydroxyl end-groups with bromoisobutyryl bromide and (iii) atom transfer radical polymerization (ATRP) of DMAEMA. The PLA block molecular weight was kept below 5000 g/mol.

Natural polyampholyte-based core-shell nanoparticles with N-carboxyethylchitosan-containing core and poly(ethylene oxide) shell.

For the first time, core-shell nanoparticles were prepared from the natural polyampholyte N-carboxyethylchitosan (CECh). This was triggered by polyelectrolyte complex (PEC) formation between CECh and strong polyelectrolyte-containing double hydrophilic block copolymers. Quaternized poly[2-(dimethylamino)ethyl methacrylate]-b-poly(ethylene oxide) (quaternized PDMAEMA-b-PEO) and sodium poly(2-acrylamido-2-methylpropane sulfonate)-b-poly(ethylene oxide) (PAMPSNa-b-PEO) were used as polycation and polyanion, respectively.

Novel biodegradable adaptive hydrogels: controlled synthesis and full characterization of the amphiphilic co-networks.

Adaptive and amphiphilic poly(N,N-dimethylamino-2-ethyl methacrylate-graft-poly[epsilon-caprolactone]) co-networks (netP(DMAEMA-g-PCL)) were synthesized from a combination of controlled polymerization techniques. Firstly, PCL cross-linkers were produced by ring-opening polymerization (ROP) of epsilon-CL initiated by 1,4-butane-diol and catalyzed by tin(II) 2-ethylhexanoate ([Sn(Oct)2]), followed by the quantitative esterification reaction of terminal hydroxyl end-groups with methacrylic anhydride. Then, PCL cross-linkers were copolymerized to DMAEMA monomers by atom-transfer radical polymerization (ATRP) in THF at 60 degrees C using CuBr complexed by 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) and 2-ethyl isobutyrylbromide (EiBBr) as catalytic complex and initiator, respectively.

Electrospun chitosan-coated fibers of poly(L-lactide) and poly(L-lactide)/poly(ethylene glycol): preparation and characterization.

Fibrous poly(L-lactide) (PLLA) and bicomponent PLLA/poly(ethylene glycol) mats were prepared by electrospinning and then were coated with chitosan. The presence of chitosan coating was proved by scanning electron microscopy and by fluorescence microscopy. On contact with blood, the chitosan coating led to changes in erythrocyte shape and in their aggregation.

Polyelectrolyte complexes based on (quaternized) poly[(2-dimethylamino)ethyl methacrylate]: behavior in contact with blood.

Polyelectrolyte complexes (PECs) between (quaternized) poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) and (crosslinked) N-carboxyethylchitosan (CECh) or poly(2-acrylamido-2-methylpropane sodium sulfonate) (PAMPSNa) were prepared and characterized in terms of their stability, equilibrium water content, and surface morphology. The evaluation of the behavior of the studied PECs in contact with blood revealed that the (crosslinked) CECh/(quaternized) PDMAEMA complexes had lost the inherent PDMAEMA cytotoxicity but still preserved haemostatic activity. In contrast, the complex formation between (quaternized) PDMAEMA and PAMPSNa allowed the preparation of materials with improved blood compatibility.

Polyelectrolyte complexes between (cross-linked) N-carboxyethylchitosan and (quaternized) poly[2-(dimethylamino)ethyl methacrylate]: preparation, characterization, and antibacterial properties.

Novel polyelectrolyte complexes (PECs) between N-carboxyethylchitosan (CECh) and well-defined (quaternized) poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) have been obtained. The modification of chitosan into CECh allows the preparation of PECs in a pH range in which chitosan cannot form complexes. The CECh/PDMAEMA complex is formed in a narrow pH range around 7.