Antoniya Toncheva

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. The antibiotics were dispersed in the coPLA or coPLA/PEG polymer matrix and the XRD spectra revealed the presence of crystalline phase characteristic of PEG and of the respective antibiotic. It was found that the release profiles of the antibiotics did not depend on the antibiotic nature but were dependent on the fiber composition. The presence of PEG in the fibers allowed a more rapid antibiotic release within the first 2h of release. The performed microbiological tests with Staphylococcus aureus revealed that the coPLA/Cipro, coPLA/PEG/Cipro, coPLA/Levo, coPLA/PEG/Levo, coPLA/Moxi and coPLA/PEG/Moxi mats inhibited the bacterial growth. In addition, the presence of an antibiotic in the mats led to a substantial decrease in the adhesion of the pathogenic microorganism and in the case of the coPLA/PEG/antibiotic series - to prevention thereof.

Polylactide (PLA)-Based Electrospun Fibrous Materials Containing Ionic Drugs as Wound Dressing Materials: A Review

The effect of the electrospinning process parameters on the morphology, alignment, and self-organization of the fibers into bundles and/or yarns are outlined. The fabrication of polylactide materials containing ionic drugs by electrospinning is emphasized. The main approaches used for the preparation of electrospun drug-loaded materials: electrospinning of a mixed solution containing the polymer(s) and the drug(s) or dual spinneret electrospinning of separate drug-containing solutions are compared. The latter approach allows the obtaining of drug-loaded fibrous materials while avoiding the drug interaction. The potential application of the obtained materials containing ionic drugs as wound dressings is outlined.

Drug-loaded electrospun polylactide bundles:

Bundle membranes were made by electrospinning poly(L-lactide) (PLLA) and PLLA/poly(ethylene glycol) (PEG) using the ionic properties of diclofenac sodium (DS), lidocaine hydrochloride (LHC), benzalkonium chloride (BC), and combinations thereof. The self-bundling of the fibers was initiated by using a designed grounded multi-needle electrode. Computer simulations on the electrostatic field distribution depended on the multi-needle position with respect to a grounded rotating drum collector which allowed the optimal arrangement of the electrospinning component set-up to obtain bundles. The combination of the ionization of the drugs as well as the utilization of the multi-needle electrode allowed the successful preparation of a series of mono-(DS, LHC, or BC), bi-(DS/LHC), and three-(DS/LHC/BC) drug(s)-loaded bundle membranes. Based on the Fourier transform infrared spectra, the drug systems were incorporated into the fibrous materials. The microbiological tests confirmed that the PLLA/ PEG bundle membranes containing BC (10 wt%), DS (30 wt%), DS/LHC (DS, 30 wt%; LHC, 30 wt%), and DS/LHC/BC (DS, 15 wt%; LHC, 15 wt%; and BC, 10 wt%) exhibited antibacterial activity against the pathogenic microorganism Staphylococcus aureus.

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. DSC and XRD analyses attested for a plasticizing effect and for increased PLA crystallinity at PBS addition to PLA. The mechanical properties of the PLA/PBS mats were controlled by the alignment of the fibers and changed from plastic to brittle materials upon increasing the PBS content. Drug loading and tests against pathogenic microorganisms suggested that the obtained mats can find application as antibacterial fibrous materials.

Curcumin-loaded poly(l-lactide-co-D,l-lactide) electrospun fibers: Preparation and antioxidant, anticoagulant, and antibacterial properties

Fibrous materials of poly(l-lactide-co-d,l-lactide), poly(l-lactide-co-d,l-lactide)/poly(ethylene glycol), and curcumin were prepared by electrospinning. The incorporation of poly(ethylene glycol) in the fibers caused a decrease in the mean fiber diameters down to 700 nm and in the water contact angle value, the latter being equal to 0 at poly(l-lactide-co-d,l-lactide)/poly(ethylene glycol) 60/40 weight ratio. The water contact angle values of poly(l-lactide-co-d,l-lactide)/curcumin fibrous materials considerably exceeded those of films of the same composition (approximately 120° as compared to approximately 95°, for electrospun mats and solution-cast films, respectively). Curcumin affected the thermal stability of the fibrous materials and the crystallinity degree of the polymers. The mechanical properties of the electrospun materials also depended on the composition of the polymer matrix and the amount of curcumin therein. In the curcumin-containing fibers, curcumin was found in the amorphous state, while higher antioxidant activity was exhibited by poly(l-lactide-co-d,l-lactide)/poly(ethylene glycol)/curcumin fibrous materials. In vitro determination of the activated partial thromboplastin time and prothrombin time showed that poly(l-lactide-co-d,l-lactide)/curcumin fibrous materials displayed anticoagulant activity. Antibacterial effect toward Staphylococcus aureus was manifested by the curcumin-containing mats.

Materials from Nanosized ZnO and Polyacrylonitrile: Properties Depending on the Design of Fibers (Electrospinning or Electrospinning/Electrospraying)

New hybrid fibrous materials from polyacrylonitrile (PAN) and nanosized zinc oxide have been prepared by electrospinning or by combining electrospinning and electrospraying techniques. Electrospinning of PAN/nanosized zinc oxide dispersion leads to the production of mats with nanofiller distributed mainly in the bulk of the fibers. Electrospinning of PAN solution performed in conjunction with electrospraying of nanosized zinc oxide dispersion enables the preparation of fibers decorated with zinc oxide particles. The incorporation of zinc oxide in the fibers leads to enhancement of the mechanical properties of the mats. The fibrous materials having zinc oxide particles situated on the fibers surface exhibit better photocatalytic activity in respect to photo-induced degradation of the model dye methylene blue and greater antibacterial activity against the pathogenic microorganism Staphylococcus aureus.

Bilayer solvent and vapor-triggered actuators made of cross-linked polymer architectures via Diels-Alder pathways

A simple and straightforward approach to produce solvent and vapor-based actuating materials is developed in this work. These actuators are based on rigidity gradients created in bilayer architectures made of reversibly cross-linked poly(e-caprolactone) (PCL) networks into which functional nanofillers, i.e. multi-walled carbon nanotubes (MWCNTs), are incorporated using simple processing techniques. A key element of the bilayer functionality lies in, by taking advantage of thermo-reversible Diels–Alder reactions (between furfuryl and maleimide moieties), ensuring good adhesion between the layers. Thereby, the produced material instantaneously swells in an anisotropic way due to the rigidity gradient, resulting in reproducible bending actuations. Besides, it is shown that the percolating network of electrically conductive MWCNTs offers the possibility of implementing these bilayers as solvent detector sensors. This opens the door to the development of multi-responsive devices with tunable actuating behaviors and potential application in the robotics field as self-deployable structures in different environments (water, organic solvents, etc.).