Drug-loaded electrospun materials in wound-dressing applications and in local cancer treatment

Nanomaterials for Functional Textiles and Fibers

Nanoparticles are very interesting because of their surface properties, different from bulk materials. Such properties make possible to endow ordinary products with new functionalities. Their relatively low cost with respect to other nano-additives make them a promising choice for industrial mass-production systems. Nanoparticles of different kind of materials such as silver, titania, and zinc oxide have been used in the functionalization of fibers and fabrics achieving significantly improved products with new macroscopic properties. This article reviews the most relevant approaches for incorporating such nanoparticles into synthetic fibers used traditionally in the textile industry allowing to give a solution to traditional problems for textiles such as the microorganism growth onto fibers, flammability, robustness against ultraviolet radiation, and many others. In addition, the incorporation of such nanoparticles into special ultrathin fibers is also analyzed. In this field, electrospinning is a very promising technique that allows the fabrication of ultrathin fiber mats with an extraordinary control of their structure and properties, being an ideal alternative for applications such as wound healing or even functional membranes.

Zein/polycaprolactone electrospun matrices for localised controlled delivery of tetracycline

We report the controlled release of the antibiotic tetracycline (Tet) from triple-layered (3L) electrospun matrices consisting of zein or a zein/PCL blend, where the drug was loaded into the central layer with the two outer layers acting as diffusion barriers. These fibrous matrices successfully encapsulated Tet and efficiently inhibited the growth of a clinical isolate, the methicillin-resistant Staphylococcus aureus strain MRSA252, as demonstrated in a modified Kirby-Bauer disc assay over 5 days. Whilst untreated zein fibres are unstable in an aqueous environment, rapidly shrinking due to plasticisation and film formation, blending zein with PCL stabilised the electrospun matrices and prevented them from shrinking. These 3L formulations display sustained antibiotic release and provide a proof of concept for zein-based polymeric matrices as wound dressings to treat or prevent bacterial infection. This is the first demonstration of the controlled release of a clinically used antibiotic from electrospun zein-based matrices.

Functional wound dressing materials with highly tunable drug release properties

Tuning of diclofenac release was achieved through incorporation into four different wound dressing materials. Proposed specific material-drug combinations could greatly improve efficiency in treatment of different wound types.

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.

Interaction of gelatin with polyenes modulates antifungal activity and biocompatibility of electrospun fiber mats

Topical application of antifungals does not have predictable or well-controlled release characteristics and requires reapplication to achieve therapeutic local concentration in a reasonable time period. In this article, the efficacy of five different US Food and Drug Administration-approved antifungal-loaded (amphotericin B, natamycin, terbinafine, fluconazole, and itraconazole) electrospun gelatin fiber mats were compared. Morphological studies show that incorporation of polyenes resulted in a two-fold increase in fiber diameter and the mats inhibit the growth of yeasts and filamentous fungal pathogens. Terbinafine-loaded mats were effective against three filamentous fungal species. Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains. However, activity loss was observed for fluconazole-loaded mats against all of the test organisms. The polyene-loaded mats displayed rapid candidacidal activities as well. Biophysical and rheological measurements indicate strong interactions between polyene antifungals and gelatin matrix. As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes. The polyene-loaded fiber mats were noncytotoxic to primary human corneal and sclera fibroblasts. The reduction of toxicity with complete retention of activity of the polyene antifungal-loaded gelatin fiber mats can provide new opportunities in the management of superficial skin infections.

Electrospinning of polymeric nanofibers for drug delivery applications

Electrospinning has been recognized as a simple and versatile method for fabrication of polymer nanofibers. Various polymers that include synthetic, natural, and hybrid materials have been successfully electrospun into ultrafine fibers. The inherently high surface to volume ratio of electrospun fibers can enhance cell attachment, drug loading, and mass transfer properties. Drugs ranging from antibiotics and anticancer agents to proteins, DNA, RNA, living cells, and various growth factors have been incorporated into electrospun fibers. This article presents an overview of electrospinning techniques and their application in drug delivery.

Mussel-inspired protein-mediated surface functionalization of electrospun nanofibers for pH-responsive drug delivery

pH-responsive drug delivery systems could mediate drug releasing rate by changing the pH values at specific times as per the pathophysiological need of the disease. This paper demonstrates that a mussel-inspired protein polydopamine coating can tune the loading and releasing rate of charged molecules from electrospun poly(ε-caprolactone) (PCL) nanofibers in solutions with different pH values. In vitro release profiles show that the positive charged molecules release significantly faster in acidic than those in neutral and basic environments within the same incubation time. The results of fluorescein diacetate staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays show the viability of cancer cells after treatment with doxorubicin-released media at different pH values qualitatively and quantitatively, indicating that the media containing doxorubicin that were released in solutions at low pH values could kill a significantly higher number of cells than those released in solutions at high pH values. Together, the pH-responsive drug delivery systems based on polydopamine-coated PCL nanofibers could have potential application in the oral delivery of anticancer drugs for treating gastric cancer and in vaginal delivery of anti-viral drugs or anti-inflammatory drugs, which could raise their efficacy, deliver them to the specific target and minimize their toxic side effects.

Gold nanorod-embedded electrospun fibrous membrane as a photothermal therapy platform

A strategy of using a gold nanorod (GNR)-loaded electrospun membrane as a photothermal therapy platform of cancer is reported. The strategy takes both the advantages of the excellent photothermal properties of GNRs to selectively kill the cancerous cells, and the widely used biodegradable electrospun membrane to serve as GNR-carrier and surgical recovery material. PEG modified GNRs were embedded into the electrospun fibrous membrane which was composed of PLGA and PLA-b-PEG with an 85:15 ratio. After incubation with the cells in the cell culture medium, the PEG-GNRs were released from the membrane and taken up by cancer cells, allowing the generation of heat upon NIR irradiation to induce cancer cell death. We have demonstrated that the use of PEG-GNR-embedded membrane selectively killed the cancerous cells and effectively inhibited cancer cell proliferation though in vitro experiments. The PEG-GNRs-loaded membrane is a promising material for postsurgical recovery of cancer.

Vacuum-assisted layer-by-layer electrospun membranes: antibacterial and antioxidative applications

Layer-by-layer assembled films have been exploited for functional materials.

In Vitro Release Characterization of Tetracycline Hydrochloride from PLGA/Tetracycline Hydrochloride Electrospun Nanofiber Mats

In order to study in vitro release behavior of hydrophilic drugs in polymer nanofibers and establish a fast characterization method, tetracycline hydrochloride-loaded poly (lacticacid-co-glycolic acid) nanofiber mats with varied tetracycline hydrochloride contents and different lacticacid to glycolic ratios in PLGA were preparied by electrospinning. Accroding to Chinese Pharmacopoeia, a basic and an improved test devices and processes were compared and their validity were commented by using an UV-visible spectrophotometer method. Results showed that the improved method can be used to estimate in vitro drug release behavior of drug-loaded mats and the results was better than the basic method. When temperature affected cumulative release ratio under controlled error, flotation method can replace the centrifugation method during the first stage of drug release testing process. Parallel experiments were carried out and results indicated that nanofibres on different part of mats had a relative stable result and repeat experimental error was kept below 4%.