Graphene Oxide Strengthens Gelatine through Non-Covalent Interactions with Its Amorphous Region

Graphene oxide (GO) has attracted huge attention in biomedical sciences due to its outstanding properties and potential applications. In this study, we synthesized GO using our recently developed 1-pyrenebutyric acid-assisted method and assessed how the GO as a filler influences the mechanical properties of GO-gelatine nanocomposite dry films as well as the cytotoxicity of HEK-293 cells grown on the GO-gelatine substrates. We show that the addition of GO (0-2%) improves the mechanical properties of gelatine in a concentration-dependent manner. The presence of 2 wt% GO increased the tensile strength, elasticity, ductility, and toughness of the gelatine films by about 3.1-, 2.5-, 2-, and 8-fold, respectively. Cell viability, apoptosis, and necrosis analyses showed no cytotoxicity from GO. Furthermore, we performed circular dichroism, X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses to decipher the interactions between GO and gelatine. The results show, for the first time, that GO enhances the mechanical properties of gelatine by forming non-covalent intermolecular interactions with gelatine at its amorphous or disordered regions. We believe that our findings will provide new insight and help pave the way for potential and wide applications of GO in tissue engineering and regenerative biomedicine.

Electrospun UV-cross-linked polyvinylpyrrolidone fibers modified with polycaprolactone/polyethersulfone microspheres for drug delivery

Electrospun fibers, often used as drug delivery systems, have two drawbacks - in the first stage of their action a sudden active substance burst release occurs and they have a relatively small capacity for a drug. In this work the fibers are modified by the addition of drug-loaded microspheres acting as micro-containers for the drug and increasing the total drug capacity of the system. Its release from such a structure is slowed down by placing the microspheres inside the fibers so they are covered with an outer layer of fiber-forming polymer. The work presents a new method (microsphere suspension electrospinning) of obtaining polyvinylpyrrolidone fibers cross-linked with UV light modified with polycaprolactone/polyethersulphone microspheres loaded with active substance - rhodamine 640 as a marker or ampicillin as a drug example. The influence of UV-cross-linking time and the microspheres addition on the degradation, mechanical strength and transport properties of fibrous mats was investigated. The mats were insoluble in water, in some cases mechanically stronger, their drug capacity was increased and the burst effect was eliminated. The antibacterial properties of ampicillin-loaded mats were confirmed. The product of proposed suspension electrospinning process has application potential as a drug delivery system.

3D Porous Collagen Matrices-A Reservoir for In Vitro Simultaneous Release of Tannic Acid and Chlorhexidine

The treatment of wounds occurring accidentally or as a result of chronic diseases most frequently requires the use of appropriate dressings, mainly to ensure tissue regeneration/healing, at the same time as treating or preventing potential bacterial infections or superinfections. Collagen type I-based scaffolds in tandem with adequate antimicrobials can successfully fulfill these requirements. In this work, starting from the corresponding hydrogels, we prepared a series of freeze-dried atelocollagen type I-based matrices loaded with tannic acid (TA) and chlorhexidine digluconate (CHDG) as active agents with a broad spectrum of antimicrobial activity and also as crosslinkers for the collagen network. The primary aim of this study was to design an original and reliable algorithm to in vitro monitor and kinetically analyze the simultaneous release of TA and CHDG from the porous matrices into an aqueous solution of phosphate-buffered saline (PBS, pH 7.4, 37 °C) containing micellar carriers of a cationic surfactant (hexadecyltrimethylammonium bromide, HTAB) as a release environment that roughly mimics human extracellular fluids in living tissues. Around this central idea, a comprehensive investigation of the lyophilized matrices (morpho-structural characterization through FT-IR spectroscopy, scanning electron microscopy, swelling behavior, resistance against the collagenolytic action of collagenase type I) was carried out. The kinetic treatment of the release data displayed a preponderance of non-Fickian-Case II diffusion behavior, which led to a general anomalous transport mechanism for both TA and CHDG, irrespective of their concentrations. This is equivalent to saying that the release regime is not governed only by the gradient concentration of the releasing components inside and outside the matrix (like in ideal Fickian diffusion), but also, to a large extent, by the relaxation phenomena of the collagen network (determined, in turn, by its crosslinking degree induced by TA and CHDG) and the dynamic capacity of the HTAB micelles to solubilize the two antimicrobials. By controlling the degree of physical crosslinking of collagen with a proper content of TA and CHDG loaded in the matrix, a tunable, sustainable release profile can be obtained.

Fibrous Polymer-Based Composites Obtained by Electrospinning for Bone Tissue Engineering

Currently, the significantly developing fields of tissue engineering related to the fabrication of polymer-based materials that possess microenvironments suitable to provide cell attachment and promote cell differentiation and proliferation involve various materials and approaches. Biomimicking approach in tissue engineering is aimed at the development of a highly biocompatible and bioactive material that would most accurately imitate the structural features of the native extracellular matrix consisting of specially arranged fibrous constructions. For this reason, the present research is devoted to the discussion of promising fibrous materials for bone tissue regeneration obtained by electrospinning techniques. In this brief review, we focus on the recently presented natural and synthetic polymers, as well as their combinations with each other and with bioactive inorganic incorporations in order to form composite electrospun scaffolds. The application of several electrospinning techniques in relation to a number of polymers is touched upon. Additionally, the efficiency of nanofibrous composite materials intended for use in bone tissue engineering is discussed based on biological activity and physiochemical characteristics.

A bifunctional electrospun nanocomposite wound dressing containing surfactin and curcumin: In vitro and in vivo studies

A double-nozzle electrospinning technique was adopted in the present study to yield a novel bifunctional wound dressing composed of curcumin (Cur) and surfactin (Sur)-loaded poly(ε-caprolactone) (PCL)-gelatin (Gel). To comprehensively unveil the effect of both composition and drug molecules on the applicability, different dressings composed of PCL, Gel, and combination of the polymers with the drug molecules were fabricated. Besides the physicochemical properties, the in vitro and in vivo biological properties of prepared wound dressings were assessed. The results showed that increasing in the Cur from 0 to 3% (w/w) and Sur from 0 to 0.2 mg/mL caused a decrease in the elastic modulus on the one hand. On the other hand, the tensile strength and elongation at break experienced an increase in their values. The wettability, swelling capacity, and degradation rate of PCL improved significantly when both Gel and the drug molecules had been added. The dressings encompassing Sur (0.2 mg/mL) exhibited an excellent antibacterial activity after 24 h (>99%). Moreover, a sustained release of Cur up to 14 days was obtained. The in vitro cell compatibility tests implied a desirable result for all dressings without taking the composition into consideration. To complement the in vitro studies, the PCL/0.2Sur-Gel/3%Cur dressing was further assessed in vivo and the results revealed a significant improvement in the healing rate compared to control groups proofing its great potential for accelerated wound healing applications.

Electrically Triggered Drug Delivery from Novel Electrospun Poly(Lactic Acid)/Graphene Oxide/Quercetin Fibrous Scaffolds for Wound Dressing Applications

The novel controlled and localized delivery of drug molecules to target tissues using an external electric stimulus makes electro-responsive drug delivery systems both feasible and desirable, as well as entailing a reduction in the side effects. Novel micro-scaffold matrices were designed based on poly(lactic acid) (PLA) and graphene oxide (GO) via electrospinning. Quercetin (Q), a natural flavonoid, was loaded into the fiber matrices in order to investigate the potential as a model drug for wound dressing applications. The physico-chemical properties, electrical triggering capacity, antimicrobial assay and biocompatibility were also investigated. The newly fabricated PLA/GO/Q scaffolds showed uniform and smooth surface morphologies, without any beads, and with diameters ranging from 1107 nm (10%PLA/0.1GO/Q) to 1243 nm (10%PLA). The in vitro release tests of Q from the scaffolds showed that Q can be released much faster (up to 8640 times) when an appropriate electric field is applied compared to traditional drug-release approaches. For instance, 10 s of electric stimulation is enough to ensure the full delivery of the loaded Q from the 10%PLA/1%GO/Q microfiber scaffold at both 10 Hz and at 50 Hz. The antimicrobial tests showed the inhibition of bacterial film growth. Certainly, these materials could be loaded with more potent agents for anti-cancer, anti-infection, and anti-osteoporotic therapies. The L929 fibroblast cells cultured on these scaffolds were distributed homogeneously on the scaffolds, and the highest viability value of 82.3% was obtained for the 10%PLA/0.5%GO/Q microfiber scaffold. Moreover, the addition of Q in the PLA/GO matrix stimulated the production of IL-6 at 24 h, which could be linked to an acute inflammatory response in the exposed fibroblast cells, as a potential effect of wound healing. As a general conclusion, these results demonstrate the possibility of developing graphene oxide-based supports for the electrically triggered delivery of biological active agents, with the delivery rate being externally controlled in order to ensure personalized release.

Electrospun Gelatin Fiber Mats Mixed With C.carandas Extract and its Enhanced Stability and Bioactivity

Crude C. carandas fruits ethanol extract (CCE) constituents important bioactive compounds such as phenolics, flavonoids, and vitamin C. Its biological activities include anti-inflammatory, antioxidant, antibacterial, etc. The present work was carried out to study the optimal conditions for fabricating electrospun gelatin fiber mats (GFM) loaded with CCE (CCE-GFM) and to evaluate the release capacity and stability of these bioactive compounds loaded into GFM. The optimal conditions for electrospinning GFM were the electrospinning 30% (w/v) gelatin solution prepared in 25% (v/v) ethanol solution containing 30% (v/v) acetic acid, under the fixed electrostatic field strength of 20 kV and at a distance between noodle tip and ground of 15 cm. The feed rate of an electrospinning solution was 1.5 mL/h. The electrospun gelatin fibers were smooth and continuous under the optimized electrospinning conditions, with an average diameter of 235.69 ± 10.45 nm. Additionally, at the loading of 15% (w/w) CCE in GFM, CCE-GFM exhibited the highest DPPH radical scavenging activity with 88.22 ± 2.62% and the highest tyrosinase inhibitory activity with 38.17 ± 1.86%. Compared with free CCE, CCE-GFM was more thermally stable upon the heating and cooling cycle testing. CCE-GFM had the percent reductions in total contents of phenolics, flavonoids and vitamin C togethering with the percent reductions of DPPH scavenging and anti-tyrosinase activities slower than pure CCE had. Furthermore, the drug release efficiency from CCE-GFM of 15% (w/w) CCE loading that was tested using modified Franz diffusion cell in an acetate buffer solution of pH 5.5 was 30%. CCE-GFM has shown the potential to utilize a facial mask sheet containing CCE valuable in high antioxidant activity for cosmetic applications.

Electrospun Nanofibers of Natural and Synthetic Polymers as Artificial Extracellular Matrix for Tissue Engineering

Many types of polymer nanofibers have been introduced as artificial extracellular matrices. Their controllable properties, such as wettability, surface charge, transparency, elasticity, porosity and surface to volume proportion, have attracted much attention. Moreover, functionalizing polymers with other bioactive components could enable the engineering of microenvironments to host cells for regenerative medical applications. In the current brief review, we focus on the most recently cited electrospun nanofibrous polymeric scaffolds and divide them into five main categories: natural polymer-natural polymer composite, natural polymer-synthetic polymer composite, synthetic polymer-synthetic polymer composite, crosslinked polymers and reinforced polymers with inorganic materials. Then, we focus on their physiochemical, biological and mechanical features and discussed the capability and efficiency of the nanofibrous scaffolds to function as the extracellular matrix to support cellular function.

A review of smart electrospun fibers toward textiles

Electrospinning as a versatile technology has attracted a large amount of attention in the past few decades due to the facile way to produce micro- and nano-scale fibers featuring flexibility, large specific surface area and high porosity. Stimuli-responsive polymers are a class of smart materials that are capable of sensing surround environment and interacting with them. Therefore, the combination of electrospinning and smart materials could have a great deal of benefits over the development of smart fibers. In this review, it offers a comprehensive understanding of smart electrospun fibers toward textile applications. Firstly, the definition of smart fibers and the differences between interactive fibers and passive interactive fibers are briefly introduced. Then some interactive fibers made from temperature-, pH-, light-, electric field/electricity-, magnetic field-, multi-responsive polymers, as well as some polymers featuring piezoelectric and triboelectric effect which are suitable flexible electrics, are emphasized with their applications in the form of electrospun fibers. Afterwards, some passive and hybrid smart electrospun fibers are introduced. Finally, associated challenges and perspectives are summarized and discussed.

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Understanding of passive smart electrospun fibers and interactive smart electrospun fibers.

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The recent progress in flexible electronics from electrospun fibers.

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The recent progress in stimuli-responsive polymers applied in interactive smart electrospun fibers.

New Oral Coaxial Nanofibers for Gadodiamide-Prospective Intestinal Magnetic Resonance Imaging and Theranostic

PURPOSE

Gadodiamide (GDD) is a widely used magnetic resonance imaging (MRI) contrast agent. It is available only as intravenous injection. Unfortunately, it exhibits a high renal toxicity. In this respect, the author investigated the possibility of developing nanofibers (NFs, one-dimensional (1D) nanostructures) of GDD that would be promising for oral administration in intestinal imaging. NFs are prepared by electrospinning technique in which a strong electrostatic field is applied on a polymer solution.

METHODS

NFs were prepared by coaxial electrospinning technique using Eudragit S100 (ES 100) as a shell layer and GDD loaded with polyvinylpyrrolidone K90 (PVP K90) and hydroxypropyl-beta-cyclodextrin (HP-β-CyD) as core fibers. Compatibility study of the NFs ingredients was attested through ATR and DSC investigations. Thermogravimetric analysis of NFs was done to insure its stability. In vitro release of GDD in the intestinal medium with different pH values was measured. In vitro cytotoxicity test was done to prove its safety. Additionally, stability of NFs to perform its function was examined by X-ray.

RESULTS

NFs experienced high entrapment efficiency of about 94.3% ± 3.1%. The ingredients of NFs were compatible through FT-IR and DSC study. The in vitro release data of GDD from coaxial NFs were slow (˂14%) in pH 1.2 till 2 h, while at pH 7.4 it showed burst release of about 12% in the first 2 min. Thermogravimetric analysis proved the NFs are stable. The in vitro cytotoxicity study proved the safety of NFs. Using mammography, the coaxial NFs behaved the same as GDD plain indicating its ability to be a contrasting agent.

CONCLUSION

Coaxial NFs of GDD as a core with PVP K90 and HP-β-CyD and ES 100 as a shell were stable and efficient as oral imaging dosage form for the intestine. It might be a prospective theranostic.

Bioactive Properties of Nanofibres Based on Concentrated Collagen Hydrolysate Loaded with Thyme and Oregano Essential Oils

This research aimed to obtain biocompatible and antimicrobial nanofibres based on concentrated collagen hydrolysate loaded with thyme or oregano essential oils as a natural alternative to synthesis products. The essential oils were successfully incorporated using electrospinning process into collagen resulting nanofibres with diameter from 471 nm to 580 nm and porous structure. The presence of essential oils in collagen nanofibre mats was confirmed by Attenuated Total Reflectance -Fourier Transform Infrared Spectroscopy (ATR-FTIR), Ultraviolet-visible spectroscopy (UV-VIS) and antimicrobial activity. Scanning Electron Microscopy with Energy Dispersive Spectroscopy analyses allowed evaluating the morphology and constituent elements of the nanofibre networks. Microbiological tests performed against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans showed that the presence of essential oils supplemented the new collagen nanofibres with antimicrobial properties. The biocompatibility of collagen and collagen with essential oils was assessed by in vitro cultivation with NCTC clone 929 of fibroblastic cells and cell viability measurement. The results showed that the collagen and thyme or oregano oil composites have no cytotoxicity up to concentrations of 1000 μg·mL^-1 and 500 μg mL^-1, respectively. Optimization of electrospinning parameters has led to the obtaining of new collagen electrospun nanofibre mats loaded with essential oils with potential use for wound dressings, tissue engineering or protective clothing.

Overview of natural hydrogels for regenerative medicine applications

Hydrogels from different materials can be used in biomedical field as an innovative approach in regenerative medicine. Depending on the origin source, hydrogels can be synthetized through chemical and physical methods. Hydrogel can be characterized through several physical parameters, such as size, elastic modulus, swelling and degradation rate. Lately, research is focused on hydrogels derived from biologic materials. These hydrogels can be derived from protein polymers, such as collage, elastin, and polysaccharide polymers like glycosaminoglycans or alginate among others. Introduction of decellularized tissues into hydrogels synthesis displays several advantages compared to natural or synthetic based hydrogels. Preservation of natural molecules such as growth factors, glycans, bioactive cryptic peptides and natural proteins can promote cell growth, function, differentiation, angiogenesis, anti-angiogenesis, antimicrobial effects, and chemotactic effects. Versatility of hydrogels make possible multiple applications and combinations with several molecules on order to obtain the adequate characteristic for each scope. In this context, a lot of molecules such as cross link agents, drugs, grow factors or cells can be used. This review focuses on the recent progress of hydrogels synthesis and applications in order to classify the most recent and relevant matters in biomedical field.

ECM-Mimetic Multiresponsive Nanobullets Targeted Against Metastasizing Circulating Tumor Clusters in Breast Cancer

Targeting smaller populations of circulating tumor clusters (CTC) with tumor-initiating and colonization potentials at distant sites in circulation remains a challenge as clusters possess both epithelial and mesenchymal characteristics. Bullet shaped ellipsoidal nanostructures of size 600 ± 11.3 nm (major axis) and 281.9 ± 5.3 nm (minor axis) with 2.2 aspect ratio were self-assembled using inorganic and organic GRAS biomaterials to preferentially target tumor-causing CTCs. Negatively-charged chondroitin sulfate in presence of gelatin guides unidirectional growth of calcium carbonate mesocrystals to form nanobullets, mediates CD44 targeting of CTCs. Switchable multi-responsive drug release profiles (temperature and pH) were recorded for nanobullets promoting spontaneous and efficient cell-killing. CD44 and E-cadherin overexpressing 'seeding' cell clusters of 170 ± 22 µm were developed as in vitro CTC model. pH responsive release of Dox into lysosome stimulates calcium influx resulting in cell death. CD44-blocked CTCs showed significantly reduced internalization when compared to CD44-expressing CTCs thereby confirming CD44 specific internalization of nanobullets. Significantly retarded expansion of clusters when shifted to cell adhesive surfaces depicts the potential of nanobullets against colonization of CTCs. Hence, newer insights on developed anisotropic ECM-mimetic nanohybrids would enhance targeted capture of tumor-initiating clusters in systemic circulation that would potentially reduce the progression of tumor in breast cancer patients.

Preparation of Lutein-Loaded PVA/Sodium Alginate Nanofibers and Investigation of Its Release Behavior

This investigation aims to study the characteristics and release properties of lutein-loaded polyvinyl alcohol/sodium alginate (PVA/SA) nanofibers prepared by electrospinning. In order to increase PVA/SA nanofibers' water-resistant ability for potential biomedical applications, the electrospun PVA/SA nanofibers were cross-linked with a mixture of glutaraldehyde and saturated boric acid solution at room temperature. The nanofibers were characterized using scanning electron microscopy (SEM) and X-ray diffractometer (XRD). Disintegration time and contact angle measurements testified the hydrophilicity change of the nanofibers before and after cross-linking. The lutein release from the nanofibers after cross-linking was measured by an ultraviolet absorption spectrophotometer, which showed sustained release up to 48 h and followed anomalous (non-Fickian) release mechanism as indicated by diffusion exponent value obtained from the Korsmeyer-Peppas equation. The results indicated that the prepared lutein-loaded PVA/SA nanofibers have great potential as a controlled release system.

Enhanced Stability and Bioactivity of Curcuma comosa Roxb. Extract in Electrospun Gelatin Nanofibers

Electrospun fiber can be used as a carrier for releasing active ingredients at the target site to achieve the effects of drug treatment. The objectives of this research work were to study suitable conditions for producing electrospun gelatin fiber loaded with crude Curcuma comosa Roxb. extract (CE) and to study antioxidant, anti-tyrosinase and anti-bacterial activities and its freeze–thaw stability as well. To achieve optimal conditions for producing electrospun gelatin fiber, the concentration of gelatin was adjusted to 30% w/v in a co-solvent system of acetic acid/water (9:1 v/v) with a feed rate of 3 mL/h and an applied voltage of 15 kV. The lowest percent loading of 5% (w/v) CE in gelatin nanofiber exhibited the highest DPPH radical scavenging activity of 94% and the highest inhibition of tyrosinase enzyme of 35%. Moreover, the inhibition zones for antibacterial activities against S. aureus and S. epidermidis were 7.77 ± 0.21 and 7.73 ± 0.12 mm, respectively. The freeze–thaw stability of CE in electrospun gelatin nanofiber was significantly different (p < 0.05) after the 4th cycle as compared to CE. Electrospun gelatin nanofiber containing CE also showed the capacity of the release of bioactive ingredients possessing anti-oxidant properties and, therefore, it could potentially be used for face masks.

Electrospun Nanofibers for Label-Free Sensor Applications

Electrospinning is a simple, low-cost and versatile method for fabricating submicron and nano size fibers. Due to their large surface area, high aspect ratio and porous structure, electrospun nanofibers can be employed in wide range of applications. Biomedical, environmental, protective clothing and sensors are just few. The latter has attracted a great deal of attention, because for biosensor application, nanofibers have several advantages over traditional sensors, including a high surface-to-volume ratio and ease of functionalization. This review provides a short overview of several electrospun nanofibers applications, with an emphasis on biosensor applications. With respect to this area, focus is placed on label-free sensors, pertaining to both recent advances and fundamental research. Here, label-free sensor properties of sensitivity, selectivity, and detection are critically evaluated. Current challenges in this area and prospective future work is also discussed.

Fabrication of Designable and Suspended Microfibers via Low-Voltage 3D Micropatterning

Building two-dimensional (2D) and three-dimensional (3D) fibrous structures in the micro- and nanoscale will offer exciting prospects for numerous applications spanning from sensors to energy storage and tissue engineering scaffolds. Electrospinning is a well-suited technique for drawing micro- to nanoscale fibers, but current methods of building electrospun fibers in 3D are restrictive in terms of printed height, design of macroscopic fiber networks, and choice of polymer. Here, we combine low-voltage electrospinning and additive manufacturing as a method to pattern layers of suspended mesofibers. Layers of fibers are suspended between 3D-printed supports in situ in multiple fiber layers and designable orientations. We examine the key working parameters to attain a threshold for fiber suspension, use those behavioral observations to establish a "fiber suspension indicator", and demonstrate its utility through design of intricate suspended fiber architectures. Individual fibers produced by this method approach the micrometer/submicrometer scale, while the overall suspended 3D fiber architecture can span over a centimeter in height. We demonstrate an application of suspended fiber architectures in 3D cell culture, utilizing patterned fiber topography to guide the assembly of suspended high-cellular-density structures. The solution-based fiber suspension patterning process we report offers a unique competence in patterning soft polymers, including extracellular matrix-like materials, in a high resolution and aspect ratio. The platform could thus offer new design and manufacturing capabilities of devices and functional products by incorporating functional fibrous elements.

Biomimetic cardiovascular platforms for in vitro disease modeling and therapeutic validation

Bioengineered tissues have become increasingly more sophisticated owing to recent advancements in the fields of biomaterials, microfabrication, microfluidics, genetic engineering, and stem cell and developmental biology. In the coming years, the ability to engineer artificial constructs that accurately mimic the compositional, architectural, and functional properties of human tissues, will profoundly impact the therapeutic and diagnostic aspects of the healthcare industry. In this regard, bioengineered cardiac tissues are of particular importance due to the extremely limited ability of the myocardium to self-regenerate, as well as the remarkably high mortality associated with cardiovascular diseases worldwide. As novel microphysiological systems make the transition from bench to bedside, their implementation in high throughput drug screening, personalized diagnostics, disease modeling, and targeted therapy validation will bring forth a paradigm shift in the clinical management of cardiovascular diseases. Here, we will review the current state of the art in experimental in vitro platforms for next generation diagnostics and therapy validation. We will describe recent advancements in the development of smart biomaterials, biofabrication techniques, and stem cell engineering, aimed at recapitulating cardiovascular function at the tissue- and organ levels. In addition, integrative and multidisciplinary approaches to engineer biomimetic cardiovascular constructs with unprecedented human and clinical relevance will be discussed. We will comment on the implementation of these platforms in high throughput drug screening, in vitro disease modeling and therapy validation. Lastly, future perspectives will be provided on how these biomimetic platforms will aid in the transition towards patient centered diagnostics, and the development of personalized targeted therapeutics.

Potential of Nanomaterial Applications in Dietary Supplements and Foods for Special Medical Purposes

Dietary supplements and foods for special medical purposes are special medical products classified according to the legal basis. They are regulated, for example, by the European Food Safety Authority and the U.S. Food and Drug Administration, as well as by various national regulations issued most frequently by the Ministry of Health and/or the Ministry of Agriculture of particular countries around the world. They constitute a concentrated source of vitamins, minerals, polyunsaturated fatty acids and antioxidants or other compounds with a nutritional or physiological effect contained in the food/feed, alone or in combination, intended for direct consumption in small measured amounts. As nanotechnology provides "a new dimension" accompanied with new or modified properties conferred to many current materials, it is widely used for the production of a new generation of drug formulations, and it is also used in the food industry and even in various types of nutritional supplements. These nanoformulations of supplements are being prepared especially with the purpose to improve bioavailability, protect active ingredients against degradation, or reduce side effects. This contribution comprehensively summarizes the current state of the research focused on nanoformulated human and veterinary dietary supplements, nutraceuticals, and functional foods for special medical purposes, their particular applications in various food products and drinks as well as the most important related guidelines, regulations and directives.

Investigation of in vitro hydrophilic and hydrophobic dual drug release from polymeric films produced by sodium alginate-MaterBi® drying emulsions

Emulsions are known to be effective carriers of hydrophobic drugs, and particularly injectable emulsions have been successfully implemented for in vivo controlled drug release. Recently, high internal phase emulsions have also been used to produce porous polymeric templates for pharmaceutical applications. However, emulsions containing dissolved biopolymers both in the oil and water phases are very scarce. In this study, we demonstrate such an emulsion, in which the oil phase contains a hydrophobic biodegradable polymer, MaterBi®, and the water phase is aqueous sodium alginate dispersion. The two phases were emulsified simply by ultrasonic processing without any surfactants. The emulsions were stable for several days and were dried into composite solid films with varying MaterBi®/alginate fractions. The films were loaded with two model drugs, a hydrophilic eosin-based cutaneous antiseptic and the hydrophobic curcumin. Drug release capacity of the films was investigated in detail, and controlled release of each model drug was achieved either by tuning the polymer fraction in the films during emulsification or by crosslinking sodium alginate fraction of the films by calcium salt solution immersion. The emulsions can be formulated to carry either a single model drug or both drugs depending on the desired application. Films demonstrate excellent cell biocompatibility against human dermal fibroblast, adult cells.

Metal alloy solid-state nanopores for single nanoparticle detection

Solid-state nanopore technology for nanoparticle sensing is considered for the development of analytical tools to characterise their size, shape or zeta potential. In this field, it is crucial to understand how the nanopore inner surface influences the dynamic of nanoparticle translocation. Here, three single nanopores directly drilled in metal alloys (titanium nitride, titanium-tantalum and tantalum) are considered. The translocation of polystyrene nanoparticles coated with ssDNA is investigated by the resistive pulse method at different concentrations and voltages. The results show that the nanoparticle energy barrier for entrance into the pore decreases for nanopores that exhibits a higher surface energy and hydrophilicity, while the dwell time is found to depend on the nanopore surface state. Overall, this study demonstrates that the control of nanopore surface state must be taken into account for the resistive pulse experiments for nanoparticle detection.

Preparation of the Potential Ocular Inserts by Electrospinning Method to Achieve the Prolong Release Profile of Triamcinolone Acetonide

Purpose: The poor bioavailability of drugs in the ocular delivery systems is an important issue and development of delivery systems with prolonged release profile could be in a major importance. This study aims to develop an ocular delivery system using electrospun nanofibers to be a candidate insert for delivery of triamcinolone acetonide.

Methods: For this purpose, three different chitosan-based formulations were prepared by electrospinning method, and electrospun nanofibers were compared to a formulation comprising hydrophobic polymers (Eudragit S100 and Zein). The electrospun nanofibers were characterized by SEM and FTIR analyses. The release profile and release kinetic models of all the formulations were also examined.

Results: The SEM photographs of electrospun nanofibers revealed that among the four designed formulations, formulation obtained by electrospinning of chitosan and PVP possessed the best quality and the minimum size (120 ±30 nm) , which resulted the most uniform and bead-free nanofibers. This formulation also possessed the prolonged release profile of triamcinolone acetonide and was the only electrospun nanofiber following the zero-order kinetic profile. Due to the small diameter and uniformity of this formulation, the prolonged and well controlled release profile, it could be taken into account as a candidate to overcome the drawbacks of the commonly used ocular delivery systems and be used as ocular insert.

Conclusion: This study confirmed the ability of electrospun nanofibers to be used as ocular inserts for delivery of ophthalmic drugs.

High photodegradation and antibacterial activity of BN–Ag/TiO2 composite nanofibers under visible light

To develop material with good photocatalytic properties for organic compound degradation and bacterial removal, we produced Ag/TiO₂ and BN–Ag/TiO₂ composite nanofibers that included controlled amounts of boron nitride (BN) nanosheets and silver (Ag).

Electrospun fibers in regenerative tissue engineering and drug delivery

Electrospinning is a versatile technique to produce micron or nano sized fibers using synthetic or bio polymers. The unique structural characteristic of the electrospun mats (ESM) which mimics extracellular matrix (ECM) found influential in regenerative tissue engineering application. ESM with different morphologies or ESM functionalizing with specific growth factors creates a favorable microenvironment for the stem cell attachment, proliferation and differentiation. Fiber size, alignment and mechanical properties affect also the cell adhesion and gene expression. Hence, the effect of ESM physical properties on stem cell differentiation for neural, bone, cartilage, ocular and heart tissue regeneration will be reviewed and summarized. Electrospun fibers having high surface area to volume ratio present several advantages for drug/biomolecule delivery. Indeed, controlling the release of drugs/biomolecules is essential for sustained delivery application. Various possibilities to control the release of hydrophilic or hydrophobic drug from the ESM and different electrospinning methods such as emulsion electrospinning and coaxial electrospinning for drug/biomolecule loading are summarized in this review.

Design of Boron Nitride/Gelatin Electrospun Nanofibers for Bone Tissue Engineering

Gelatin is a biodegradable biopolymer obtained by collagen denaturation, which shows poor mechanical properties. Hence, improving its mechanical properties is very essential toward the fabrication of efficient nontoxic material for biomedical applications. For this aim, various methods are employed using external fillers such as ceramics or bioglass. In this report, we introduce boron nitride (BN)-reinforced gelatin as a new class of two-dimensional biocompatible nanomaterials. The effect of the nanofiller on the mechanical behavior is analyzed. BN is efficiently exfoliated using the biopolymer gelatin as shown through Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The exfoliated BN reinforces gelatin electrospun fibers, which results in an increase in the Young's modulus. The Electrospun Mats (ESM) are stable after the glutaraldehyde cross-linking, and the fibrous morphology is preserved. The cross-linked gelatin/BN ESM is highly bioactive in forming bonelike hydroxyapatite as shown by scanning electron microscopy. Due to their enhanced mineralization ability, the cross-linked ESM have been tested on human bone cells (HOS osteosarcoma cell line). The cell attachment, proliferation, and biocompatibility results show that the ESM are nontoxic and biodegradable. The analysis of osteoblast gene expression and the measurement of alkaline phosphatase activity confirm that these materials are suitable for bone tissue engineering.

Optimization of the Silver Nanoparticles PEALD Process on the Surface of 1-D Titania Coatings

Plasma enhanced atomic layer deposition (PEALD) of silver nanoparticles on the surface of 1-D titania coatings, such as nanotubes (TNT) and nanoneedles (TNN), has been carried out. The formation of TNT and TNN layers enriched with dispersed silver particles of strictly defined sizes and the estimation of their bioactivity was the aim of our investigations. The structure and the morphology of produced materials were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron miscroscopy (SEM). Their bioactivity and potential usefulness in the modification of implants surface have been estimated on the basis of the fibroblasts adhesion and proliferation assays, and on the basis of the determination of their antibacterial activity. The cumulative silver release profiles have been checked with the use of inductively coupled plasma-mass spectrometry (ICPMS), in order to exclude potential cytotoxicity of silver decorated systems. Among the studied nanocomposite samples, TNT coatings, prepared at 3, 10, 12 V and enriched with silver nanoparticles produced during 25 cycles of PEALD, revealed suitable biointegration properties and may actively counteract the formation of bacterial biofilm.

Pharmaceutical Intermediate-Modified Gold Nanoparticles: Against Multidrug-Resistant Bacteria and Wound-Healing Application via an Electrospun Scaffold

Remedying a multidrug-resistant (MDR) bacteria wound infection is a major challenge due to the inability of conventional antibiotics to treat such infections against MDR bacteria. Thus, developing wound dressings for wound care, particularly against MDR bacteria, is in huge demand. Here, we present a strategy in designing wound dressings: we use a small molecule (6-aminopenicillanic acid, APA)-coated gold nanoparticles (AuNPs) to inhibit MDR bacteria. We dope the AuNPs into electrospun fibers of poly(ε-caprolactone) (PCL)/gelatin to yield materials that guard against wound infection by MDR bacteria. We systematically evaluate the bactericidal activity of the AuNPs and wound-healing capability via the electrospun scaffold. APA-modified AuNPs (Au_APA) exhibit remarkable antibacterial activity even when confronted with MDR bacteria. Meanwhile, Au_APA has outstanding biocompatibility. Moreover, an in vivo bacteria-infected wound-healing experiment indicates that it has a striking ability to remedy a MDR bacteria wound infection. This wound scaffold can assist the wound care for bacterial infections.

Advances in Hybrid Polymer-Based Materials for Sustained Drug Release

The use of biomaterials composed of organic pristine components has been successfully described in several purposes, such as tissue engineering and drug delivery. Drug delivery systems (DDS) have shown several advantages over traditional drug therapy, such as greater therapeutic efficacy, prolonged delivery profile, and reduced drug toxicity, as evidenced by in vitro and in vivo studies as well as clinical trials. Despite that, there is no perfect delivery carrier, and issues such as undesirable viscosity and physicochemical stability or inability to efficiently encapsulate hydrophilic/hydrophobic molecules still persist, limiting DDS applications. To overcome that, biohybrid systems, originating from the synergistic assembly of polymers and other organic materials such as proteins and lipids, have recently been described, yielding molecularly planned biohybrid systems that are able to optimize structures to easily interact with the targets. This work revised the biohybrid DDS clarifying their advantages, limitations, and future perspectives in an attempt to contribute to further research of innovative and safe biohybrid polymer-based system as biomaterials for the sustained release of active molecules.

Design of graphene oxide/gelatin electrospun nanocomposite fibers for tissue engineering applications

2D graphene oxide (GO) is used to enhance the mechanical properties of gelatin electrospun fibers. The GO does not show any significant influence on cell viability and cell attachment even though the expression of osteoblast gene is affected.