Electrospun Nanofibrous Scaffolds-Current Status and Prospects in Drug Delivery

Poly(N-isopropylacrylamide) based smart nanofibrous scaffolds for use as on-demand delivery systems for oral and dental tissue regeneration

Stimuli-responsive domains capable of releasing loaded molecules, "on-demand," have garnered increasing attention due to their enhanced delivery, precision targeting, and decreased adverse effects. The development of an on-demand delivery system that can be easily triggered by dental clinicians might have major roles in dental and oral tissue engineering. A series of random graft poly(NIPAm-co-HEMA-Lactate) copolymers were synthesized using 95:5, 85:5, 60:40, and 40:60 ratios of thermosensitive NIPAm and HEMA-poly lactate respectively then electrospun to produce nanofibrous scaffolds loaded with bovine serum albumin (BSA). Cumulative BSA release was assessed at 25C and 37°C. To appraise the use of scaffolds as on-demand delivery systems, they were subjected to thermal changes in the form cooling and warming cycles during which BSA release was monitored. To confirm the triggered releasing ability of the synthesized scaffolds, the copolymer made with 60% NIPAm was selected, based on the results of the release tests, and loaded with bone morphogenetic protein-2 (BMP-2). The loaded scaffolds were placed with mesenchymal-like stem cells (iMSCs) derived from induced pluripotent stem cells (iPSCs), and subjected to temperature alterations. Then, the osteogenic differentiation of iMSCs, which might have resulted from the released protein, was evaluated after 10 days by analyzing runt-related transcription factor 2 (RUNX-2) osteogenic gene expression by the cells using real-time quantitative polymerase chain reaction (qRT-PCR). BSA release profiles showed a burst release at the beginning followed by a more linear pattern at 25°C, and a much slower release at 37°C. The release also decreased when the PNIPAm content decreased in the scaffolds. Thermal triggering led to a step-like release pattern in which the highest release was reported 30 min through the warming cycles. The iMSCs cultivated with scaffolds loaded with BMP-2 and exposed to temperature alteration showed significantly higher RUNX-2 gene expression than cells in the other experimental groups. The synthesized scaffolds are thermo-responsive and could be triggered to deliver biological biomolecules to be used in oral and dental tissue engineering. Thermal stimuli could be simulated by dental clinicians using simple means of cold therapy, for example, cold packs in intraoral accessible sites for specified times.

Drug-Loaded Chitosan Scaffolds for Periodontal Tissue Regeneration

Chitosan is a natural anionic polysaccharide with a changeable architecture and an abundance of functional groups; in addition, it can be converted into various shapes and sizes, making it appropriate for a variety of applications. This article examined and summarized current developments in chitosan-based materials, with a focus on the modification of chitosan, and presented an abundance of information about the fabrication and use of chitosan-derived products in periodontal regeneration. Numerous preparation and modification techniques for enhancing chitosan performance, as well as the uses of chitosan and its metabolites, were reviewed critically and discussed in depth in this study. Chitosan-based products may be formed into different shapes and sizes, considering fibers, nanostructures, gels, membranes, and hydrogels. Various drug-loaded chitosan devices were discussed regarding periodontal regeneration.

Novel biodegradable and non-fouling systems for controlled-release based on poly(ε-caprolactone)/Quercetin blends and biomimetic bacterial S-layer coatings

Quercetin is a strong antioxidant with low bioavailability due to its high crystallinity. A further drawback is that Quercetin has potentially toxic effects at high concentrations. To improve this low water solubility, as well as control the concentration of the flavonoid in the body, Quercetin is incorporated into a polymeric matrix to form an amorphous solid dispersion (ASD) stable enough to resist the recrystallization of the drug. For this purpose, miscible poly(ε-caprolactone) (PCL) and Quercetin (Q) blends are prepared, provided that they have complementary interacting groups. For compositions in which the flavonoid remains in an amorphous state thanks to the interactions with polymer chains, various PCL/Q drug release platforms are fabricated: micrometric films by solvent casting, nanometric films by spin coating, and nanofibers by electrospinning. Then, the potential use of bacterial S-layer proteins as release-preventive membranes is tested on PCL-Quercetin blends, due to their ability to construct a biomimetic coating including nanometric pores. For all the platforms, the SbpA coating can maintain a stable release under the toxicity level of Quercetin. Accordingly, a PCL/Q system with an S-layer coating allows the design of versatile bioavailable Quercetin eluting devices that prevent toxicity and biofouling issues.

Preparation and Characterization of Tetrahydrocurcumin-Loaded Cellulose Acetate Phthalate/Polyethylene Glycol Electrospun Nanofibers

A simple composite electrospun nanofiber of cellulose acetate phthalate (CAP)-polyethylene glycol (PEG) loaded with tetrahydrocurcumin (THC) was developed in this study, and the in vitro diffusion of THC was evaluated. The nanofibers were characterized by scanning electron microscopy, powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC). The formulated nanofiber (NF) with THC has smooth morphology with diameter of around 300-500 nm. The complete entrapment and dispersion of THC was observed from the results of PXRD and DSC due to the loss of THC crystalline property. Further, FT-IR demonstrated that the vibration bands for the polymers used were dominant over the THC, and the vibrational bands of THC were not observed from the final formulation. The drug entrapment by the final CAP + PEG NF was found to be 95.5% with the high swelling index. From the in vitro release study, it was found that the formulated THC-loaded CAP + PEG NF has followed anomalous mechanism, demonstrating both diffusion and swelling controlled modes. The drug release extended up to 12 h with a final cumulative release of 94.24%.

Electrospun polyurethane nanofibrous composite impregnated with metallic copper for wound-healing application

In this study, a wound dressing based on polyurethane (PU) blended with copper sulphate nanofibers was developed using an electrospinning technique. The prepared PU and PU nanocomposites showed smooth fibers without any bead defects. The prepared nanocomposites showed smaller fiber (663 ± 156.30 nm) and pore (888 ± 70.93 nm) diameter compared to the pristine PU (fiber diameter 1159 ± 147.48 nm and pore diameter 1087 ± 62.51 nm). The interaction of PU with copper sulphate was evident in the infrared spectrum through hydrogen-bond formation. Thermal analysis displayed enhanced weight residue at higher temperature suggesting interaction of PU with copper sulphate. The contact angle measurements revealed the hydrophilic nature of the prepared nanocomposites (71° ± 2.309°) compared with pure PU (100° ± 0.5774°). The addition of copper sulphate into the PU matrix increased the surface roughness, as revealed in the atomic force microscopy (AFM) analysis. Mechanical testing demonstrated the enhanced tensile strength behavior of the fabricated nanocomposites (18.58 MPa) compared with the pristine PU (7.12 MPa). The coagulation assays indicated the enhanced blood compatibility of the developed nanocomposites [activated partial thromboplastin time (APTT)-179 ± 3.606 s and partial thromboplastin time (PT)-105 ± 2.646 s] by showing a prolonged blood clotting time compared with the pristine PU (APTT-147.7 ± 3.512 s and PT-84.67 ± 2.517 s). Furthermore, the hemolysis and cytotoxicity studies suggested a less toxicity nature of prepared nanocomposites by displaying low hemolytic index and enhanced cell viability rates compared with the PU membrane. It was observed that the fabricated novel wound dressing possesses better physicochemical and enhanced blood compatibility properties, and may be utilized for wound-healing applications.

Nanofibrous scaffolds for biomedical applications

Tissue engineering is an emergent and very interesting research field, providing potential solutions for a myriad of challenges in healthcare. Fibrous scaffolds specifically have shown promise as an effective tissue engineering method, as their high length-to-width ratio mimics that of extracellular matrix components, which in turn guides tissue formation, promotes cellular adhesion and improves mechanical properties. In this review paper, we discuss in detail both the importance of fibrous scaffolds for the promotion of tissue growth and the different methods to produce fibrous biomaterials to possess favorable and unique characteristics. Here, we focus on the pressing need to develop biomimetic structures that promote an ideal environment to encourage tissue formation. In addition, we discuss different biomedical applications in which fibrous scaffolds can be useful, identifying their importance, relevant aspects, and remaining significant challenges. In conclusion, we provide comments on the future direction of fibrous scaffolds and the best way to produce them, proposed in light of recent technological advances and the newest and most promising fabrication techniques.

Transferrin-conjugated nanodiamond as an intracellular transporter of chemotherapeutic drug and targeting therapy for cancer cells

AIM

PEGylated fluorescent nanodiamond (FND) conjugated with Tf (FND-PEG-Tf) was investigated for targeted drug delivery.

MATERIALS & METHODS

Human hepatoma (HepG2) and normal (L-02) cell lines were used to investigate the difference in cellular uptake of FND-PEG-Tf and its loading drug system. Nanoparticle uptake was evaluated by flow cytometry and laser scanning confocal microscopy.

RESULTS

FND-PEG-Tf showed highly specific TfR-mediated uptake by HepG2 cells, relative to negative controls (L-02 cell), which was a strong correlation among TfR density on the cell surface. The mechanism of TfR-mediated uptake was attested by free Tf with Fe³⁺ as a competitive agent. The difference in cell viability between L-02 and HepG2 cells treated with doxorubicin hydrochloride (DOX) nanoparticles (FND-PEG-Tf-DOX) can be explained by FND-PEG-Tf, which can target drug delivery to cancer cells.

CONCLUSION

FND-PEG-Tf can potentially be utilized in targeted cancer cell imaging and effective drug delivery for cancer therapy.

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.

Use of ginsenoside Rg3-loaded electrospun PLGA fibrous membranes as wound cover induces healing and inhibits hypertrophic scar formation of the skin

Prevention of hypertrophic scar formation of the skin requires a complex treatment process, which mainly includes promoting skin regeneration in an early stage while inhibiting hypertrophic formation in a later stage. Electrospinning PLGA with the three-dimensional micro/nano-fibrous structure and as drugs carrier, could be used as an excellent skin repair scaffold. However, it is difficult to combine the advantage of nanofibrous membranes and drug carriers to achieve early and late treatment. In this study, Ginsenoside-Rg3 (Rg3) loaded hydrophilic poly(D,L-lactide-co-glycolide) (PLGA) electrospun fibrous membranes coated with chitosan (CS) were fabricated by combining electrospinning and pressure-driven permeation (PDP) technology. The PDP method was able to significantly improve the hydrophilicity of electrospun fibrous membranes through surface coating of the hydrophilic fibers with CS, while maintaining the Rg3 releasing rate of PLGA electrospun fibrous membranes. Experimental wounds of animal covered with PDP treated fibrous membranes completely re-epithelialized and healed 3-4 days earlier than the wounds in control groups. Scar elevation index (SEI) measurements and histologic characteristics revealed that Rg3 significantly inhibited scar formation 28 days post-surgery. Moreover, RT-PCR assays and western blot analysis revealed that at day 28 after wound induction the expression of VEGF, mRNA and Collagen Type I in the scars treated with Rg3 was decreased compared to control groups. Taken together PLGA-Rg3/CS electrospun fibrous membranes induced repair of tissue damage in the early stage and inhibited scar formation in the late stage of wound healing. These dual-functional membranes present a combined therapeutic approach for inhibiting hypertrophic scars of the skin.

Acceleration of dermal wound healing by using electrospun curcumin-loaded poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) fibrous mats

This study prepared a composite scaffold composed of curcumin and poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) copolymer using coelectrospinning technology. Incorporation of curcumin into the polymeric matrix had an obvious effect on the morphology and dimension of PCEC/curcumin fibers. The results of in vitro anti-oxidant tests and of the cytotoxicity assay demonstrated that the curcumin-loaded PCEC fibrous mats had significant anti-oxidant efficacy and low cytotoxicity. Curcumin could be sustainably released from the fibrous scaffolds. More importantly, in vivo efficacy in enhancing wound repair was also investigated based on a full-thickness dermal defect model for Wistar rats. The results indicated that the PCEC/curcumin fibrous mats had a significant advantage in promoting wound healing. At 21 days post-operation, the dermal defect was basically recovered to its normal condition. A percentage of wound closure reached up to 93.3 ± 5.6% compared with 76.9 ± 4.9% of the untreated control (p < 0.05). Therefore, the as-prepared PCEC/curcumin composite mats are a promising candidate for use as wound dressing.

Trapping tetracycline-loaded nanoparticles into polycaprolactone fiber networks for periodontal regeneration therapy

The controlled delivery of antibiotics, anti-inflammatory agents, or chemotherapeutic agents to the periodontal site is a recognized strategy to improve the efficiency of regenerative processes of hard tissues. A novel approach based on the trapping of tetracycline hydrochloride–loaded particles in polycaprolactone nanofibers was used to guide the regeneration processes of periodontal tissue at the gum interface. Chitosan nanoparticles loaded with different levels of tetracycline hydrochloride (up to 5% wt) were prepared by solution nebulization induced by electrical forces (i.e. electrospraying). The fine tuning of process parameters allows to obtain nanoparticles with tailored sizes ranging from 0.485 ± 0.147 µm to 0.639 ± 0.154 µm. The tetracycline hydrochloride release profile had a predominant burst effect for the first 70% of release followed by a relatively slow release over 24 h, which is promising for oral drug delivery. We also demonstrated that trapping tetracycline hydrochloride–loaded particles with submicrometer diameters into a polycaprolactone fiber network contributed to slowing the release of tetracycline hydrochloride from the nanoparticles, thus providing a more prolonged release in the periodontal pocket during clinical therapy. Preliminary studies on human mesenchymal stem cells confirm the viability of cells up to 5 days after culture, and thereby, validate the use of nanoparticle-/nanofiber-integrated systems in periodontal therapies.

Wound-dressing materials with antibacterial activity from electrospun polyurethane-dextran nanofiber mats containing ciprofloxacin HCl

Dextran is a versatile biomacromolecule for preparing electrospun nanofibrous membranes by blending with either water-soluble bioactive agents or hydrophobic biodegradable polymers for biomedical applications. In this study, an antibacterial electrospun scaffold was prepared by electrospinning of a solution composed of dextran, polyurethane (PU) and ciprofloxacin HCl (CipHCl) drug. The obtained nanofiber mats have good morphology. The mats were characterized by various analytical techniques. The interaction parameters between fibroblasts and the PU-dextran and PU-dextran-drug scaffolds such as viability, proliferation, and attachment were investigated. The results indicated that the cells interacted favorably with the scaffolds especially the drug-containing one. Moreover, the composite mat showed good bactericidal activity against both of Gram-positive and Gram-negative bacteria. Overall, our results conclude that the introduced scaffold might be an ideal biomaterial for wound dressing applications.