Impact of PCL nanofiber mat structural properties on hydrophilic drug release and antibacterial activity on periodontal pathogens

Synthesis of star-shaped poly(lactide)s, poly(valerolactone)s and poly(caprolactone)s via ROP catalyzed by N-donor tin(ii) cations and comparison of their wetting properties with linear analogues

In this study, we report the use of N-coordinated tin(ii) cations [L1→Sn(H2O)][OTf]2·THF (1) and [L1→SnCl][SnCl3] (2) (L1 = 1,2-(C5H4N-2-CH = N)2CH2CH2) as efficient ROP catalysts, which, in combination with benzyl alcohol, afford well-defined linear poly(ε-caprolactone) (PCL) and poly(δ-valerolactones) (PVL) via an activated monomer mechanism (AMM). Thanks to the versatility of complexes 1 and 2 as catalysts, star-shaped PCL, PVL and PLA were also prepared using three-, four-, five- and six-functional alcohols. The number of arms was determined by SEC-MALS-Visco analysis. Spin-coated thin layers of linear and selected six-armed polymers were further studied in terms of their wettability to water. Attention was focused on the influence of the composition and structure of the polymers. Finally, to increase the hydrophobic properties of the studied polymers, stannaboroxines L2(Ph)Sn[(OB-(C6H4-4-CF3))2O] and L2(Ph)Sn[(OB-(C6H4-3,5-CF3)2)2O] (L2 = C6H3-2,6-(Me2NCH2)2) were applied.

In vitro experimental conditions and tools can influence the safety and biocompatibility results of antimicrobial electrospun biomaterials for wound healing

Electrospun (ES) fibrous nanomaterials have been widely investigated as novel biomaterials. These biomaterials have to be safe and biocompatible; hence, they need to be tested for cytotoxicity before being administered to patients. The aim of this study was to develop a suitable and biorelevant in vitro cytotoxicity assay for ES biomaterials (e.g. wound dressings). We compared different in vitro cytotoxicity assays, and our model wound dressing was made from polycaprolactone and polyethylene oxide and contained chloramphenicol as the active pharmaceutical ingredient. Baby Hamster Kidney cells (BHK-21), human primary fibroblasts and MTS assays together with real-time cell analysis were selected. The extract exposure and direct contact safety evaluation setups were tested together with microscopic techniques. We found that while extract exposure assays are suitable for the initial testing, the biocompatibility of the biomaterial is revealed in in vitro direct contact assays where cell interactions with the ES wound dressing are evaluated. We observed significant differences in the experimental outcome, caused by the experimental set up modification such as cell line choice, cell medium and controls used, conducting the phosphate buffer washing step or not. A more detailed technical protocol for the in vitro cytotoxicity assessment of ES wound dressings was developed.

Preparation and Characterization of Chitosan Nanofiber: Kinetic Studies and Enhancement of Insulin Delivery System

Insulin-loaded nanofibers were prepared using chitosan as a natural polymer. The loaded insulin with polyethylene oxide was used for preparing monolayer batch S1. Nanofiber S1 was coated by seven layers of film on both sides to form batch S2 as a sandwich containing Layer A (CS, PEG and PEO) and Layer B (PEG and PEO) using electrospinning apparatus. SEM, TEM and FT-IR techniques were used to confirm the drug loading within the composite nanofibers. The in vitro activity that provided a sustained and controlled release of the drug from the nanofiber batch was studied at different pH values spectrophotometrically using a dialysis method. In batches S1 and S2, the release of insulin from nanofiber proceeds via burst release necessary to produce the desired therapeutic activity, followed by slow step. The rate and the percentage release of insulin in batch S2 are found to be higher at all pH values.

Impact of local drug delivery and natural agents as new target strategies against periodontitis: new challenges for personalized therapeutic approach

Periodontitis is a persistent inflammation of the soft tissue around the teeth that affects 60% of the population in the globe. The self-maintenance of the inflammatory process can cause periodontal damage from the alveolar bone resorption to tooth loss in order to contrast the effects of periodontitis, the main therapy used is scaling and root planing (SRP). At the same time, studying the physiopathology of periodontitis has shown the possibility of using a local drug delivery system as an adjunctive therapy. Using local drug delivery devices in conjunction with SRP therapy for periodontitis is a potential tool since it increases drug efficacy and minimizes negative effects by managing drug release. This review emphasized how the use of local drug delivery agents and natural agents could be promising adjuvants for the treatment of periodontitis patients affected or not by cardiovascular disease, diabetes, and other system problems. Moreover, the review evidences the current issues and new ideas that can inspire potential later study for both basic research and clinical practice for a tailored approach.

Research Progress on Nanomaterials for Tissue Engineering in Oral Diseases

Due to their superior antibacterial properties, biocompatibility and high conductivity, nanomaterials have shown a broad prospect in the biomedical field and have been widely used in the prevention and treatment of oral diseases. Also due to their small particle sizes and biodegradability, nanomaterials can provide solutions for tissue engineering, especially for oral tissue rehabilitation and regeneration. At present, research on nanomaterials in the field of dentistry focuses on the biological effects of various types of nanomaterials on different oral diseases and tissue engineering applications. In the current review, we have summarized the biological effects of nanoparticles on oral diseases, their potential action mechanisms and influencing factors. We have focused on the opportunities and challenges to various nanomaterial therapy strategies, with specific emphasis on overcoming the challenges through the development of biocompatible and smart nanomaterials. This review will provide references for potential clinical applications of novel nanomaterials in the field of oral medicine for the prevention, diagnosis and treatment of oral diseases.

Development of In Vitro and Ex Vivo Biofilm Models for the Assessment of Antibacterial Fibrous Electrospun Wound Dressings

Increasing evidence suggests that the chronicity of wounds is associated with the presence of bacterial biofilms. Therefore, novel wound care products are being developed, which can inhibit biofilm formation and/or treat already formed biofilms. A lack of standardized assays for the analysis of such novel antibacterial drug delivery systems enhances the need for appropriate tools and models for their characterization. Herein, we demonstrate that optimized and biorelevant in vitro and ex vivo wound infection and biofilm models offer a convenient approach for the testing of novel antibacterial wound dressings for their antibacterial and antibiofilm properties, allowing one to obtain qualitative and quantitative results. The in vitro model was developed using an electrospun (ES) thermally crosslinked gelatin-glucose (GEL-Glu) matrix and an ex vivo wound infection model using pig ear skin. Wound pathogens were used for colonization and biofilm development on the GEL-Glu matrix or pig skin with superficial burn wounds. The in vitro model allowed us to obtain more reproducible results compared with the ex vivo model, whereas the ex vivo model had the advantage that several pathogens preferred to form a biofilm on pig skin compared with the GEL-Glu matrix. The in vitro model functioned poorly for Staphylococcus epidermidis biofilm formation, but it worked well for Escherichia coli and Staphylococcus aureus, which were able to use the GEL-Glu matrix as a nutrient source and not only as a surface for biofilm growth. On the other hand, all tested pathogens were equally able to produce a biofilm on the surface of pig skin. The developed biofilm models enabled us to compare different ES dressings [pristine and chloramphenicol-loaded polycaprolactone (PCL) and PCL-poly(ethylene oxide) (PEO) (PCL/PEO) dressings] and understand their biofilm inhibition and treatment properties on various pathogens. Furthermore, we show that biofilms were formed on the wound surface as well as on a wound dressing, indicating that the demonstrated methods mimic well the in vivo situation. Colony forming unit (CFU) counting and live biofilm matrix as well as bacterial DNA staining together with microscopic imaging were performed for biofilm quantification and visualization, respectively. The results showed that both wound biofilm models (in vitro and ex vivo) enabled the evaluation of the desired antibiofilm properties, thus facilitating the design and development of more effective wound care products and screening of various formulations and active substances.

Electrospun fibers as carriers for topical drug delivery and release in skin bandages and patches for atopic dermatitis treatment

The skin is a complex layer system and the most important barrier between the environment and the organism. In this review, we describe some widespread skin problems, with a focus on eczema, which are affecting more and more people all over the world. Most of treatment methods for atopic dermatitis (AD) are focused on increasing skin moisture and protecting from bacterial infection and external irritation. Topical and transdermal treatments have specific requirements for drug delivery. Breathability, flexibility, good mechanical properties, biocompatibility, and efficacy are important for the patches used for skin. Up to today, electrospun fibers are mostly used for wound dressing. Their properties, however, meet the requirements for skin patches for the treatment of AD. Active agents can be incorporated into fibers by blending, coaxial or side-by-side electrospinning, and also by physical absorption post-processing. Drug release from the electrospun membranes is affected by drug and polymer properties and the technique used to combine them into the patch. We describe in detail the in vitro release mechanisms, parameters affecting the drug transport, and their kinetics, including theoretical approaches. In addition, we present the current research on skin patch design. This review summarizes the current extensive know-how on electrospun fibers as skin drug delivery systems, while underlining the advantages in their prospective use as patches for atopic dermatitis. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Polymeric Nanofibers for Drug Delivery Applications: A Recent Review

With the rapid development of biomaterials and biotechnologies, various functional materials-based drug delivery systems (DDS) are developed to overcome the limitations of traditional drug release formulations, such as uncontrollable drug concentration in target organs/tissues and unavoidable adverse reactions. Polymer nanofibers exhibit promising characteristics including easy preparation, adjustable features of wettability and elasticity, tailored surface and interface properties, and surface-to-volume ratio, and are used to develop new DDS. Different kinds of drugs can be incorporated into the polymer nanofibers. Additionally, their release kinetics can be modulated via the preparation components, component proportions, and preparation processes, enabling their applications in several fields. A timely and comprehensive summary of polymeric nanofibers for DDS is thus highly needed. This review first describes the common methods for polymer nanofiber fabrication, followed by introducing controlled techniques for drug loading into and release from polymer nanofibers. Thus, the applications of polymer nanofibers in drug delivery were summarized, particularly focusing on the relation between the physiochemical properties of polymeric nanofibers and their DDS performance. It is ended by listing future perspectives. Graphical abstract.

Electrospun Nanofiber Composites for Drug Delivery: A Review on Current Progresses

A medication’s approximate release profile should be sustained in order to generate the desired therapeutic effect. The drug’s release site, duration, and rate must all be adjusted to the drug’s therapeutic aim. However, when designing drug delivery systems, this may be a considerable hurdle. Electrospinning is a promising method of creating a nanofibrous membrane since it enables drugs to be placed in the nanofiber composite and released over time. Nanofiber composites designed through electrospinning for drug release purposes are commonly constructed of simple structures. This nanofiber composite produces matrices with nanoscale fiber structure, large surface area to volume ratio, and a high porosity with small pore size. The nanofiber composite’s large surface area to volume ratio can aid with cell binding and multiplication, drug loading, and mass transfer processes. The nanofiber composite acts as a container for drugs that can be customized to a wide range of drug release kinetics. Drugs may be electrospun after being dissolved or dispersed in the polymer solution, or they can be physically or chemically bound to the nanofiber surface. The composition and internal structure of the nanofibers are crucial for medicine release patterns.

Nanostructured Electrospun Polycaprolactone-Propolis Mats Composed of Different Morphologies for Potential Use in Wound Healing

This study aimed to investigate different types of morphologies obtained using the electrospinning process to produce a material that enables wound healing while performing a controlled release. Using benign solvents, the authors prepared and characterised electrospun polycaprolactone mats loaded with propolis, a popular extract in traditional medicine with potential for skin repair. Different morphologies were obtained from distinct storage periods of the solution before electrospinning to investigate the effect of PCL hydrolysis (average diameters of fibres and beads: 159.2-280.5 nm and 1.9-5.6 μm, respectively). Phytochemical and FTIR analyses of the extract confirmed propolis composition. GPC and viscosity analyses showed a decrease in polymer molecular weight over the storage period (about a 70% reduction over 14 days) and confirmed that it was responsible for the nanostructure diversity. Moreover, propolis acted as a lubricant agent, affecting the spun solutions' viscosity and the thermal properties and hydrophilicity of the mats. All samples were within the value range of the water vapour transpiration rate of the commercial products (1263.08 to 2179.84 g/m²·day). Even though the presence of beads did not affect the propolis release pattern, an in vitro wound-healing assay showed that propolis-loaded mats composed of beaded fibres increased the cell migration process. Thus, these films could present the potential for use in wound dressing applications.

Metronidazole Topically Immobilized Electrospun Nanofibrous Scaffold: Novel Secondary Intention Wound Healing Accelerator

The process of secondary intention wound healing includes long repair and healing time. Electrospun nanofibrous scaffolds have shown potential for wound dressing. Biopolymers have gained much attention due to their remarkable characteristics such as biodegradability, biocompatibility, non-immunogenicity and nontoxicity. This study anticipated to develop a new composite metronidazole (MTZ) immobilized nanofibrous scaffold based on poly (3-hydroxy butyrate) (PHB) and Gelatin (Gel) to be utilized as a novel secondary intention wound healing accelerator. Herein, PHB and Gel were mixed together at different weight ratios to prepare polymer solutions with final concentration of (7%), loaded with two different concentrations 5% (Z₁) and 10% (Z₂) of MTZ. Nanofibrous scaffolds were obtained by manipulating electrospinning technique. The properties of MTZ immobilized PHB/Gel nanofibrous scaffold were evaluated (SEM, FTIR, TGA, water uptake, contact angle, porosity, mechanical properties and antibacterial activity). Additionally, in vitro cytocompatibility of the obtained nanofibrous scaffolds were assessed by using the cell counting kit-8 (CCK-8 assay). Moreover, in vivo wound healing experiments revealed that the prepared nanofibrous scaffold highly augmented the transforming growth factor (TGF-β) signaling pathway, moderately suppressed the pro-inflammatory cytokine (IL-6). These results indicate that MTZ immobilized PHB/Gel nanofibrous scaffold significantly boost accelerating secondary intention wound healing.

Applications of Novel and Nanostructured Drug Delivery Systems for the Treatment of Oral Cavity Diseases

PURPOSE

Novel drug delivery systems (DDSs) hold great promise for the treatment of oral cavity diseases. The main objective of this article was to provide a detailed overview regarding recent advances in the use of novel and nanostructured DDSs in alleviating and treating unpleasant conditions of the oral cavity. Strategies to maximize the benefits of these systems in the treatment of oral conditions and future directions to overcome these issues are also discussed.

METHODS

Publications from the last 10 years investigating novel and nanostructured DDSs for pathologic oral conditions were browsed in a systematic search using the PubMed/MEDLINE, Web of Science, and Scopus databases. Research on applications of novel DDSs for periodontitis, oral carcinomas, oral candidiasis, xerostomia, lichen planus, aphthous stomatitis, and oral mucositis is summarized. A narrative exploratory review of the most recent literature was undertaken.

FINDINGS

Conventional systemic administration of therapeutic agents could exhibit high clearance of drugs from the bloodstream and low accumulation at the target site. In contrast, conventional topical systems face problems such as short residence time in the affected region and low patient compliance. Novel and nanostructured DDSs are among the most effective and commonly used methods for overcoming the problems of conventional DDSs. The main advantages of these systems are that they possess the ability to protect active agents from systemic and local clearance, enhance bioavailability and cellular uptake, and provide immediate or modified release of therapeutic agents after administration. In the design of local drug delivery devices such as nanofiber mats, films, and patches, components and excipients can significantly affect factors such as drug release rate, residence time in the oral cavity, and taste in the mouth. Choosing appropriate additives is therefore essential.

IMPLICATIONS

Local drug delivery devices such as nanofiber mats, nanoparticles, liposomes, hydrogels, films, and patches for oral conditions can significantly affect drug efficacy and safety. However, more precise clinical studies should be designed and conducted to confirm promising in vitro and in vivo results. In recent years, novel and nanostructured DDSs increasingly attracted the attention of researchers as a means of treatment and alleviation of oral diseases and unpleasant conditions. However, more clinical studies should be performed to confirm promising in vitro and in vivo results. To transform a successful laboratory model into a marketable product, the long-term stability of prepared formulations is essential. Also, proper scale-up methods with optimum preparation costs should be addressed.

Antimicrobial and Antibiofilm Activity of Curcumin-Loaded Electrospun Nanofibers for the Prevention of the Biofilm-Associated Infections

Curcumin extracted from the rhizome of Curcuma Longa has been used in therapeutic preparations for centuries in different parts of the world. However, its bioactivity is limited by chemical instability, water insolubility, low bioavailability, and extensive metabolism. In this study, the coaxial electrospinning technique was used to produce both poly (ε-caprolactone) (PCL)-curcumin and core-shell nanofibers composed of PCL and curcumin in the core and poly (lactic acid) (PLA) in the shell. Morphology and physical properties, as well as the release of curcumin were studied and compared with neat PCL, showing the formation of randomly oriented, defect-free cylindrical fibers with a narrow distribution of the dimensions. The antibacterial and antibiofilm potential, including the capacity to interfere with the quorum-sensing mechanism, was evaluated on Pseudomonas aeruginosa PAO1, and Streptococcus mutans, two opportunistic pathogenic bacteria frequently associated with infections. The reported results demonstrated the ability of the Curcumin-loading membranes to inhibit both PAO1 and S. mutans biofilm growth and activity, thus representing a promising solution for the prevention of biofilm-associated infections. Moreover, the high biocompatibility and the ability to control the oxidative stress of damaged tissue, make the synthesized membranes useful as scaffolds in tissue engineering regeneration, helping to accelerate the healing process.

Encapsulation of Pharmaceutical and Nutraceutical Active Ingredients Using Electrospinning Processes

Electrospinning is an inexpensive and powerful method that employs a polymer solution and strong electric field to produce nanofibers. These can be applied in diverse biological and medical applications. Due to their large surface area, controllable surface functionalization and properties, and typically high biocompatibility electrospun nanofibers are recognized as promising materials for the manufacturing of drug delivery systems. Electrospinning offers the potential to formulate poorly soluble drugs as amorphous solid dispersions to improve solubility, bioavailability and targeting of drug release. It is also a successful strategy for the encapsulation of nutraceuticals. This review aims to briefly discuss the concept of electrospinning and recent progress in manufacturing electrospun drug delivery systems. It will further consider in detail the encapsulation of nutraceuticals, particularly probiotics.

Treatment challenges and delivery systems in immunomodulation and probiotic therapies for periodontitis

Introduction: Periodontitis is a widespread illness that arises due to disrupted interplay between the oral microbiota and the host immune response. In some cases, conventional therapies can provide temporary remission, although this is often followed by disease relapse. Recent studies of periodontitis pathology have promoted the development of new therapeutics to improve treatment options, together with local application using advanced drug delivery systems.Areas covered: This paper provides a critical review of the status of current treatment approaches to periodontitis, with a focus on promising immunomodulation and probiotic therapies. These are based on delivery of small molecules, peptides, proteins, DNA or RNA, and probiotics. The key findings on novel treatment strategies and formulation of advanced delivery systems, such as nanoparticles and nanofibers, are highlighted.Expert opinion: Multitarget therapy based on antimicrobial, immunomodulatory, and probiotic active ingredients incorporated into advanced delivery systems for application to the periodontal pocket can improve periodontitis treatment outcomes. Translation of such adjuvant therapy from laboratory to patient is expected in the future.

Multidrug-loaded electrospun micro/nanofibrous membranes: Fabrication strategies, release behaviors and applications in regenerative medicine

Electrospun micro/nanofibrous membranes (EFMs) have been widely investigated as local drug delivery systems. Multiple drugs can be simultaneously incorporated into one EFM to create synergistic effects, reduce side effects, and play their respective roles in the complex physiological processes of tissue regeneration and postoperative adhesion prevention. Due to the versatile electrospinning techniques, sustained and programmed release behaviors of multiple drugs could be achieved by modulating the structure of the EFMs and the location of the drugs. In this review, various multidrug incorporation approaches based on electrospinning are overviewed. In particular, the advantages and limitations of each drug incorporation technique, the methods to control drug release and the effect of one drug release on another are discussed. Then the applications of multidrug-loaded EFMs in regenerative medicine, including wound healing, bone regeneration, vascular tissue engineering, nerve regeneration, periodontal regeneration and adhesion prevention are comprehensively reviewed. Finally, the future perspectives and challenges in the research of multidrug-loaded EFMs are discussed.

Personalized Reusable Face Masks with Smart Nano-Assisted Destruction of Pathogens for COVID-19: A Visionary Road

The Coronavirus disease 2019 (COVID-19) emergency has demonstrated that the utilization of face masks plays a critical role in limiting the outbreak. Healthcare professionals utilize masks all day long without replacing them very frequently, thus representing a source of cross-infection for patients and themselves. Nanotechnology is a powerful tool with the capability to produce nanomaterials with unique physicochemical and antipathogen properties. Here, how to realize non-disposable and highly comfortable respirators with light-triggered self-disinfection ability by bridging bioactive nanofiber properties and stimuli-responsive nanomaterials is outlined. The visionary road highlighted in this Concept is based on the possibility of developing a new generation of masks based on multifunctional membranes where the presence of nanoclusters and plasmonic nanoparticles arranged in a hierarchical structure enables the realization of a chemically driven and on-demand antipathogen activities. Multilayer electrospun membranes have the ability to dissipate humidity present within the mask, enhancing the wearability and usability. The photothermal disinfected membrane is the core of these 3D printed and reusable masks with moisture pump capability. Personalized face masks with smart nano-assisted destruction of pathogens will bring enormous advantages to the entire global community, especially for front-line personnel, and will open up great opportunities for innovative medical applications.

Preparation and characterization of novel anti-inflammatory biological agents based on piroxicam-loaded poly-ε-caprolactone nano-particles for sustained NSAID delivery

Piroxicam (PX), a main member of non-steroidal anti-inflammatory drugs (NSAIDs), is mainly used orally, which causes side effects of the gastrointestinal tract. It also has systemic effects when administered intramuscularly. Intra-articular (IA) delivery and encapsulation of PX in biodegradable poly-ε-caprolactone (PCL) nanoparticles (NPs) offer potential advantages over conventional oral delivery. The purpose of this study is the development of a new type of anti-inflammatory bio-agents containing collagen and PX-loaded NPs, as an example for an oral formulation replacement, for the prolonged release of PX. In this study, the PX was encapsulated in PCL NPs (size 102.7 ± 19.37 nm, encapsulation efficiency 92.83 ± 0.4410) by oil-in-water (o/w) emulsion solvent evaporation method. Nanoparticles were then characterized for entrapment efficiency, percent yield, particle size analysis, morphological characteristics, and in vitro drug release profiles. Eventually, the NPs synthesized with collagen were conjugated so that the NPs were trapped in the collagen sponges using a cross-linker. Finally, biocompatibility tests showed that the anti-inflammatory agents made in this study had no toxic effect on the cells. Based on the results, it appears that PX-loaded PCL NPs along with collagen (PPCLnp-Coll) can be promising for IA administration based on particulate drug delivery for the treatment of arthritis.

Antibacterial Porous Electrospun Fibers as Skin Scaffolds for Wound Healing Applications

Electrospun fiber scaffolds have a huge potential for the successful treatment of infected wounds based on their unique properties. Although several studies report novel drug-loaded electrospun fiber-based biomaterials, many of these do not provide information on their interactions with eukaryotic and bacterial cells. The main aim of this study was to develop antibacterial drug-loaded porous biocompatible polycaprolactone (PCL) fiber scaffolds mimicking the native extracellular matrix for wound healing purposes. Mechanical property evaluation and different biorelevant tests were conducted in order to understand the structure-activity relationships and reveal how the surface porosity of fibers and the fiber diameter affect the scaffold interactions with the living bacterial and eukaryotic fibroblast cells. Cell migration and proliferation assays and antibiofilm assays enabled us to enlighten the biocompatibility and safety of fiber scaffolds and their suitability to be used as scaffolds for the treatment of infected wounds. Here, we report that porous PCL microfiber scaffolds obtained using electrospinning at high relative humidity served as the best surfaces for fibroblast attachment and growth compared to the nonporous microfiber or nonporous nanofiber PCL scaffolds. Porous chloramphenicol-loaded microfiber scaffolds were more elastic compared to nonporous scaffolds and had the highest antibiofilm activity. The results indicate that in addition to the fiber diameter and fiber scaffold porosity, the single-fiber surface porosity and its effect on drug release, mechanical properties, cell viability, and antibiofilm activity need to be understood when developing antibacterial biocompatible scaffolds for wound healing applications. We show that pores on single fibers within an electrospun scaffold, in addition to nano- and microscale diameter of the fibers, change the living cell-fiber interactions affecting the antibiofilm efficacy and biocompatibility of the scaffolds for the local treatment of wounds.

Fabrication of tri-layered electrospun polycaprolactone mats with improved sustained drug release profile

Modulation of initial burst and long term release from electrospun fibrous mats can be achieved by sandwiching the drug loaded mats between hydrophobic layers of fibrous polycaprolactone (PCL). Ibuprofen (IBU) loaded PCL fibrous mats (12% PCL-IBU) were sandwiched between fibrous polycaprolactone layers during the process of electrospinning, by varying the polymer concentrations (10% (w/v), 12% (w/v)) and volume of coat (1 ml, 2 ml) in flanking layers. Consequently, 12% PCL-IBU (without sandwich layer) showed burst release of 66.43% on day 1 and cumulative release (%) of 86.08% at the end of 62 days. Whereas, sandwich groups, especially 12% PCLSW-1 & 2 (sandwich layers-1 ml and 2 ml of 12% PCL) showed controlled initial burst and cumulative (%) release compared to 12% PCL-IBU. Moreover, crystallinity (%) and hydrophobicity of the sandwich models imparted control on ibuprofen release from fibrous mats. Further, assay for cytotoxicity and scanning electron microscopic images of cell seeded mats after 5 days showed the mats were not cytotoxic. Nuclear Magnetic Resonance spectroscopic analysis revealed weak interaction between ibuprofen and PCL in nanofibers which favors the release of ibuprofen. These data imply that concentration and volume of coat in flanking layer imparts tighter control on initial burst and long term release of ibuprofen.

Highly Elastic and Water Stable Zein Microfibers as a Potential Drug Delivery System for Wound Healing

The development of biomaterials for wound healing applications requires providing a number of properties, such as antimicrobial action, facilitation of cell proliferation, biocompatibility and biodegradability. The aim of the present study was to investigate morphological and mechanical properties of zein-based microfibers, ultimately aimed at creating an environment suitable for wound healing. This was achieved through co-axial electrospinning of core-shell microfibers, with zein protein in the core and polyethylene oxide (PEO) in the shell. Small amounts of PEO or stearic acid were additionally incorporated into the fiber core to modify the morphology and mechanical properties of zein fibers. The presence of PEO in the core was found to be essential for the formation of tubular fibers, whereas PEO in the shell enhanced the stability of the microfibers in water and ensured high elasticity of the microfiber mats. Tetracycline hydrochloride was present in an amorphous form within the fibers, and displayed a burst release as a result of pore-formation in the fibers. The developed systems exhibited antimicrobial activity against Staphylococcus aureus and Escherichia coli, and showed no cytotoxic effect on fibroblasts. Biocompatibility, antimicrobial activity and favorable morphological and mechanical properties make the developed zein-based microfibers a potential biomaterial for wound healing purposes.

Nanofibers as drug-delivery systems for infection control in dentistry

INTRODUCTION

Due to the complexity of different oral infections, new anti-infective nanotechnological approaches have been emerging for dentistry in recent years. These strategies may contribute to antimicrobial molecules delivery, tissue regeneration, and oral health maintenance by acting in a more specific site and not being cytotoxic. In this context, nanofibers appear as versatile structures and might act both in the release of antimicrobial molecules and as a scaffold for new tissue formation.

AREAS COVERED

This review addresses the application of different nanofibers as new strategies for the delivery of antimicrobial molecules for dentistry. Here, we present the main polymers used to construct nanofibers, methods of production and mainly their antimicrobial activity against microorganisms commonly responsible for the usual dental infections. These biomaterials may be associated to restorative materials, prostheses, and mucoadhesive structures. Besides, nanofibers can be used for endodontic or periodontal therapy, or even on implant surfaces.

EXPERT OPINION

A wide variety of studies report the potential application of anti-infective nanofibers in the oral cavity. Although there are still several barriers between in vitro and in vivo studies, these new formulations appear as promising new therapies for dentistry.

Quasi-Dynamic Dissolution of Electrospun Polymeric Nanofibers Loaded with Piroxicam

We investigated and monitored in situ the wetting and dissolution properties of polymeric nanofibers and determined the solid-state of a drug during dissolution. Piroxicam (PRX) was used as a low-dose and poorly-soluble model drug, and hydroxypropyl methylcellulose (HPMC) and polydextrose (PD) were used as carrier polymers for electrospinning (ES). The initial-stage dissolution of the nanofibers was monitored in situ with three-dimensional white light microscopic interferometry (SWLI) and high-resolution optical microscopy. The physical solid-state characterization of nanofibers was performed with Raman spectroscopy, X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). We showed that PRX recrystallizes in a microcrystalline form immediately after wetting of nanofibers, which could lead to enhanced dissolution of drug. Initiation of crystal formation was detected by SWLI, indicating: (1) that PRX was partially released from the nanofibers, and (2) that the solid-state form of PRX changed from amorphous to crystalline. The amount, shape, and size of the PRX crystals depended on the carrier polymer used in the nanofibers and dissolution media (pH). In conclusion, the present nanofibers loaded with PRX exhibit a quasi-dynamic dissolution via recrystallization. SWLI enables a rapid, non-contacting, and non-destructive method for in situ monitoring the early-stage dissolution of nanofibers and regional mapping of crystalline changes (re-crystallization) during wetting. Such analysis is crucial because the wetting and dissolution of nanofibers can greatly influence the performance of nanofibrous drug delivery systems in pharmaceutical and biomedical applications.

Monitoring of Antimicrobial Drug Chloramphenicol Release from Electrospun Nano- and Microfiber Mats Using UV Imaging and Bacterial Bioreporters

New strategies are continuously sought for the treatment of skin and wound infections due to increased problems with non-healing wounds. Electrospun nanofiber mats with antibacterial agents as drug delivery systems provide opportunities for the eradication of bacterial infections as well as wound healing. Antibacterial activities of such mats are directly linked with their drug release behavior. Traditional pharmacopoeial drug release testing settings are not always suitable for analyzing the release behavior of fiber mats intended for the local drug delivery. We tested and compared different drug release model systems for the previously characterized electrospun chloramphenicol (CAM)-loaded nanofiber (polycaprolactone (PCL)) and microfiber (PCL in combination with polyethylene oxide) mats with different drug release profiles. Drug release into buffer solution and hydrogel was investigated and drug concentration was determined using either high-performance liquid chromatography, ultraviolet-visible spectrophotometry, or ultraviolet (UV) imaging. The CAM release and its antibacterial effects in disc diffusion assay were assessed by bacterial bioreporters. All tested model systems enabled to study the drug release from electrospun mats. It was found that the release into buffer solution showed larger differences in the drug release rate between differently designed mats compared to the hydrogel release tests. The UV imaging method provided an insight into the interactions with an agarose hydrogel mimicking wound tissue, thus giving us information about early drug release from the mat. Bacterial bioreporters showed clear correlations between the drug release into gel and antibacterial activity of the electrospun CAM-loaded mats.

Electrospun fibers and their application in drug controlled release, biological dressings, tissue repair, and enzyme immobilization

Electrospinning is a method of preparing microfibers or nanofibers by using an electrostatic force to stretch the electrospinning fluid. Electrospinning has gained considerable attention in many fields due to its ability to produce continuous fibers from a variety of polymers and composites in a simple way. Electrospun nanofibers have many merits such as diverse chemical composition, easily adjustable structure, adjustable diameter, high surface area, high porosity, and good pore connectivity, which give them broad application prospects in the biomedical field. This review systematically introduced the factors influencing electrospinning, the types of electrospun fibers, the types of electrospinning, and the detailed applications of electrospun fibers in controlled drug release, biological dressings, tissue repair and enzyme immobilization fields. The latest progress of using electrospun fibers in these fields was summarized, and the main challenges to be solved in electrospinning technology were put forward.

Polylactide nanofibers delivering doxycycline for chronic wound treatment

Chronic wounds are of high incidence, difficult to heal, and can cause serious consequences if not properly treated. Doxycycline (DCH) is a broad-spectrum antibiotic and matrix metalloproteinases inhibitor, which has prominent efficacy for chronic wound treatment. Topical DCH treatment is the common administration route for chronic wounds in clinic but may result in low therapeutic efficacy and cause skin irritation at high DCH concentration, since it is difficult to control local drug concentration in the wounds and maintain the effective DCH concentration for a long time. In this study, we prepared DCH-encapsulated polylactide (DCH/PLA) nanofibers by a simple electrospinning method. Imaging studies showed that smooth and continuous DCH/PLA nanofibers with homogeneous DCH distribution were obtained at varied DCH loading content in the range of 5-30%. Mechanical property, water vapour permeability and absorbency of these nanofibers could meet the requirement as wound dressings. By adjusting DCH loading content, the wettability of the nanofibers could be transferred from hydrophobic to hydrophilic, and the release rate of DCH could be controlled in a sustained manner from three days to two weeks. Results of cytotoxicity and antibacterial test indicated that DCH/PLA nanofibers showed good cytocompatibility to L929 mouse fibroblast cells and exhibited positive antibacterial activity against Escherichia coli, suggesting its ability to treat/prevent infectious wounds. For full-thickness wound treatment of diabetic rats, DCH/PLA nanofiber mats can speed up wound healing to a higher extent than topical DCH treatment, due to the sustained release of DCH with less side effects. Our results indicate that DCH/PLA nanofiber mats hold great potential as wound dressings for chronic wound treatment.

Core-shell nanofibers as drug delivery systems

Core-shell nanofibers have grown in popularity over the last decade owing to their special features and their many applications in biomedicine. They can be produced by electrospinning of immiscible polymer blends or emulsions through a single nozzle or by electrospinning using a coaxial nozzle. Several of the electrospinning parameters allow great versatility for the compositions and diameters of core-shell nanofibers to be produced. Morphology of core-shell nanofibers can be investigated using transmission electron microscopy and, in some cases, scanning electron microscopy. Several studies have shown that core-shell nanofibers have some advantages over monolithic nanofibers, such as better drug, protein, gene or probiotic incorporation into the nanofibers, greater control over drug release, and maintenance of protein structure and activity during electrospinning. We herein review the production and characterization of core-shell nanofibers, the critical parameters that affect their development, and their advantages as delivery systems.

Corona alternating current electrospinning: A combined approach for increasing the productivity of electrospinning

Corona alternating current electrospinning (C-ACES), a scaled-up productivity electrospinning method was developed by combining the intense forces of the alternating electrostatic field and a sharp-edged spinneret design with increased free surface. C-ACES reached two orders of magnitude higher productivity (up to 1200 mL/h) than the classical single needle direct current electrospinning (DCES) without any alteration of fiber properties. Polyvinylpyrrolidone K90 (PVPK90), a water soluble high molecular weight nonionic polymer was processed for the first time with single needle alternating current electrospinning (ACES) and C-ACES in order to prepare fast dissolving amorphous solid dispersions of spironolactone (SPIR), a poorly water-soluble antihypertensive model drug. The limited spinnability of PVPK90 with AC high voltage could only be resolved by optimizing the solution conductivity with organophilic salts such as sodium dodecyl sulfate (SDS) demonstrating the importance of conductivity during ACES. The effects of varied solution properties (composition and conductivity) and scaling-up were investigated by SEM imaging. Solid state analyses revealed that SPIR was dispersed in an amorphous form in the fibrous mats. In vitro dissolution tests showed ultrafast drug release in case of the amorphous formulations even when prepared with scaled-up C-ACES. Besides the enhancement of conductivity SDS also prevents SPIR from precipitation from the dissolution media due to its solubilization ability.

Novel Bioactive and Therapeutic Dental Polymeric Materials to Inhibit Periodontal Pathogens and Biofilms

Periodontitis is a common infectious disease characterized by loss of tooth-supporting structures, which eventually leads to tooth loss. The heavy burden of periodontal disease and its negative consequence on the patient's quality of life indicate a strong need for developing effective therapies. According to the World Health Organization, 10⁻15% of the global population suffers from severe periodontitis. Advances in understanding the etiology, epidemiology and microbiology of periodontal pocket flora have called for antibacterial therapeutic strategies for periodontitis treatment. Currently, antimicrobial strategies combining with polymer science have attracted tremendous interest in the last decade. This review focuses on the state of the art of antibacterial polymer application against periodontal pathogens and biofilms. The first part focuses on the different polymeric materials serving as antibacterial agents, drug carriers and periodontal barrier membranes to inhibit periodontal pathogens. The second part reviews cutting-edge research on the synthesis and evaluation of a new generation of bioactive dental polymers for Class-V restorations with therapeutic effects. They possess antibacterial, acid-reduction, protein-repellent, and remineralization capabilities. In addition, the antibacterial photodynamic therapy with polymeric materials against periodontal pathogens and biofilms is also briefly described in the third part. These novel bioactive and therapeutic polymeric materials and treatment methods have great potential to inhibit periodontitis and protect tooth structures.

Understanding the impact of crosslinked PCL/PEG/GelMA electrospun nanofibers on bactericidal activity

Herein, we report the design of electrospun ultrathin fibers based on the combination of three different polymers polycaprolactone (PCL), polyethylene glycol (PEG), and gelatin methacryloyl (GelMA), and their potential bactericidal activity against three different bacteria Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the morphology, chemical structure and wettability before and after UV photocrosslinking of the produced scaffolds. Results showed that the developed scaffolds presented hydrophilic properties after PEG and GelMA incorporation. Moreover, they were able to significantly reduce gram-positive, negative, and MRSA bacteria mainly after UV photocrosslinking (PCL:PEG:GelMa-UV). Furthermore, we performed a series of study for gaining a better mechanistic understanding of the scaffolds bactericidal activity through protein adsorption study and analysis of the reactive oxygen species (ROS) levels. Furthermore, the in vivo subcutaneous implantation performed in rats confirmed the biocompatibility of our designed scaffolds.