Staff

Abstract:
This work presents the synthesis and characterization of a composite made of superparamagnetic iron oxide and hydroxyapatite nanoparticles (SPION/HAp) with a well-developed surface for loading anticancer drugs and for use in magnetic hyperthermia and local chemotherapy. The proposed material was obtained by an easy one-pot co-precipitation method with a controlled ratio of SPION to HAp. The morphology was studied by SEM and TEM, indicating rod-like structures for high HAp content in the composite and granule-like structures with increasing SPION. Its crystallinity, elemental composition, and functional groups were determined by X-ray diffraction, EDS, and FT-IR, respectively. The nanocomposite was then stabilized with citrates (CA), polyethylene glycol (PEG), and folic acid (FA) as agents to improve intracellular absorption, while turbidimetric studies confirmed that only citrates effectively stabilized the magnetic carriers to form a colloidal suspension. Subsequently, 5-fluorouracil (5-FU) was loaded into the magnetic carriers and tested in vitro using the L-929 cell line. The studies showed no cytotoxicity of the citrate-stabilized suspension against fibroblasts and some cytotoxicity after 5-FU release. In addition to in vitro studies, the composite was also tested on biomimetic membranes made of DOPC, DOPE, cholesterol, and DOPS lipids using Langmuir trough. The results show that the resulting suspension interacts with biomimetic membranes, while magnetic hyperthermia studies confirm effective heat generation to achieve therapeutic 42–46 °C and improve drug release from magnetic carriers.

Keywords:
SPION, Hydroxyapatite, Magnetic hyperthermia, Drug delivery, 5-fluorouracil, Biomimetic membranes, Nanostructures, Cancer treatment

Abstract:
Current treatments of degenerated intervertebral discs often provide only temporary relief or address specific causes, necessitating the exploration of alternative therapies. Cell-based regenerative approaches showed promise in many clinical trials, but
limitations such as cell death during injection and a harsh disk environment hinder their effectiveness. Injectable microscaffolds offer a solution by providing a supportive microenvironment for cell delivery and enhancing bioactivity. This study evaluated the
safety and feasibility of electrospun nanofibrous microscaffolds modified with chitosan (CH) and chondroitin sulfate (CS) for treating degenerated NP tissue in a large animal model. The microscaffolds facilitated cell attachment and acted as an effective delivery system, preventing cell leakage under a high disc pressure. Combining microscaffolds with bone marrow-derived mesenchymal stromal cells demonstrated no cytotoxic effects and proliferation over the entire microscaffolds. The administration of cells attached to microscaffolds into the NP positively influenced the regeneration process of the intervertebral disc. Injectable poly(L-lactide-co-glycolide) and poly(L-lactide) microscaffolds enriched with CH or CS, having a fibrous structure, showed the potential to promote intervertebral disc regeneration. These features collectively address critical challenges in the fields of tissue engineering and regenerative medicine, particularly in the context of intervertebral disc degeneration.

Keywords:
microscaffolds,cell carriers,injectable biomaterials,intervertebral disc,laser micromachining,electrospinning

Abstract:
The Anterior Cruciate Ligament (ACL) is one of the major knee ligaments, one which is greatly exposed to injuries. According to the British National Health Society, ACL tears represent around 40% of all knee injuries. The number of ACL injuries has increased rapidly over the past ten years, especially in people from 26–30 years of age. We present a brief background in currently used ACL treatment strategies with a description of surgical reconstruction techniques. According to the well-established method, the PubMed database was then analyzed to scaffold preparation methods and materials. The number of publications and clinical trials over the last almost 30 years were analyzed to determine trends in ACL graft development. Finally, we described selected ACL scaffold development publications of engineering, medical, and business interest. The systematic PubMed database analysis indicated a high interest in collagen for the purpose of ACL graft development, an increased interest in hybrid grafts, a numerical balance in the development of biodegradable and nonbiodegradable grafts, and a low number of clinical trials. The investigation of selected publications indicated that only a few suggest a real possibility of creating healthy tissue. At the same time, many of them focus on specific details and fundamental science. Grafts exhibit a wide range of mechanical properties, mostly because of polymer types and graft morphology. Moreover, most of the research ends at the in vitro stage, using non-certificated polymers, thus requiring a long time before the medical device can be placed on the market. In addition to scientific concerns, official regulations limit the immediate introduction of artificial grafts onto the market.

Keywords:
ligament,biomaterial,tissue engineering,regeneration,implant,scaffold,synthetic polymer,natural polymer

Abstract:
The use of injectable biomaterials for cell delivery is a rapidly expanding field which may revolutionize the medical treatments by making them less invasive. However, creating desirable cell carriers poses significant challenges to the clinical implementation of cell-based therapeutics. At the same time, no method has been developed to produce injectable microscaffolds (MSs) from electrospun materials. Here the fabrication of injectable electrospun nanofibers is reported on, which retain their fibrous structure to mimic the extracellular matrix. The laser-assisted micro-scaffold fabrication has produced tens of thousands of MSs in a short time. An efficient attachment of cells to the surface and their proliferation is observed, creating cell-populated MSs. The cytocompatibility assays proved their biocompatibility, safety, and potential as cell carriers. Ex vivo results with the use of bone and cartilage tissues proved that NaOH hydrolyzed and chitosan functionalized MSs are compatible with living tissues and readily populated with cells. Injectability studies of MSs showed a high injectability rate, while at the same time, the force needed to eject the load is no higher than 25 N. In the future, the produced MSs may be studied more in-depth as cell carriers in minimally invasive cell therapies and 3D bioprinting applications.

Abstract:
The paper presents the effect of He+ ion irradiation of selected polymeric materials: poly(tetrafloroethylene), poly(vinyl chloride), ethylene-propylene-diene monomer rubber, nitrile-butadiene rubber, styrene-butadiene rubber, and natural rubber, on their chemical composition, physical structure, and surface topography. The modification was studied by scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and differential scanning calorimetry. Irradiation with a high-energy ion beam leads to the release of significant amounts of hydrogen from the surface layer, resulting in an increase in cross-linking that manifests itself by shrinkage of the surface layer, which in turn causes significant stresses leading to the formation of a crack pattern on the polymer surface. The development of microroughness is combined with oxidation. Shallow range of the ions makes the modified layer “anchored” in the substrate via bulk macromolecules, assuring its good durability and adhesion to elasto-plastic substrates. Changes in the surface layer were manifested by the modification of functional properties of the polymers. The hardness of the layer subjected to the ion irradiation process increases even up to 10 times. After modification with the ion beam, a significant decrease in frictional forces was also observed, even up to 5–6 times. The microscopic analysis of wear traces confirmed that the wear resistance also significantly increased. However, ion bombardment of polymeric materials caused a reduction in their mechanical strength (despite the range limited to the surface layer of the order of micrometers) and electrical resistance, which has a negative impact on the possibility of using the materials in some applications.

Abstract:
Intrinsically conducting polymers (ICPs) are widely used to fabricate biomaterials; their application in neural tissue engineering, however, is severely limited because of their hydrophobicity and insufficient mechanical properties. For these reasons, soft conductive polymer hydrogels (CPHs) are recently developed, resulting in a water-based system with tissue-like mechanical, biological, and electrical properties. The strategy of incorporating ICPs as a conductive component into CPHs is recently explored by synthesizing the hydrogel around ICP chains, thus forming a semi-interpenetrating polymer network (semi-IPN). In this work, a novel conductive semi-IPN hydrogel is designed and synthesized. The hybrid hydrogel is based on a poly(N-isopropylacrylamide-co-N-isopropylmethacrylamide) hydrogel where polythiophene is introduced as an ICP to provide the system with good electrical properties. The fabrication of the hybrid hydrogel in an aqueous medium is made possible by modifying and synthesizing the monomers of polythiophene to ensure water solubility. The morphological, chemical, thermal, electrical, electrochemical, and mechanical properties of semi-IPNs were fully investigated. Additionally, the biological response of neural progenitor cells and mesenchymal stem cells in contact with the conductive semi-IPN was evaluated in terms of neural differentiation and proliferation. Lastly, the potential of the hydrogel solution as a 3D printing ink was evaluated through the 3D laser printing method. The presented results revealed that the proposed 3D printable conductive semi-IPN system is a good candidate as a scaffold for neural tissue applications.

Abstract:
The spread of antimicrobial resistance requires the development of novel strategies to combat superbugs. Bacteriolytic enzymes (enzybiotics) that selectively eliminate pathogenic bacteria, including resistant strains and biofilms, are attractive alternatives to antibiotics, also as a component of a new generation of antimicrobial wound dressings. AuresinePlus is a novel, engineered enzybiotic effective against Staphylococcus aureus—one of the most common pathogenic bacteria, found in infected wounds with a very high prevalence of antibiotic resistance. We took advantage of its potent lytic activity, selectivity, and safety to prepare a set of biodegradable PLGA/chitosan fibers generated by electrospinning. Our aim was to produce antimicrobial nonwovens to deliver enzybiotics directly to the infected wound and better control its release and activity. Three different methods of enzyme immobilization were tested: physical adsorption on the previously hydrolyzed surface, and covalent bonding formation using N-hydroxysuccinimide/N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide (NHS/EDC) or glutaraldehyde (GA). The supramolecular structure and functional properties analysis revealed that the selected methods resulted in significant development of nanofibers surface topography resulting in an efficient enzybiotic attachment. Both physically adsorbed and covalently bound enzymes (by NHS/EDC method) exhibited prominent antibacterial activity. Here, we present the extensive comparison between methods for the effective attachment of the enzybiotic to the electrospun nonwovens to generate biomaterials effective against antibiotic-resistant strains. Our intention was to present a comprehensive proof-of-concept study for future antimicrobial wound dressing development.

Keywords:
antibacterial wound dressings, enzybiotic, fibers functionalization, electrospun wound dressings, Staphylococcus aureus

Abstract:
Multifunctional nanomaterials with the ability torespond to near-infrared (NIR) light stimulation are vital for thedevelopment of highly efficient biomedical nanoplatforms with apolytherapeutic approach. Inspired by the mesoglea structure ofjellyfish bells, a biomimetic multifunctional nanostructured pillowwith fast photothermal responsiveness for NIR light-controlled on-demand drug delivery is developed. We fabricate a nanoplatformwith several hierarchical levels designed to generate a series ofcontrolled, rapid, and reversible cascade-like structural changesupon NIR light irradiation. The mechanical contraction of thenanostructured platform, resulting from the increase of temper-ature to 42°C due to plasmonic hydrogel−light interaction, causesa rapid expulsion of water from the inner structure, passing through an electrospun membrane anchored onto the hydrogel core. Themutual effects of the rise in temperature and waterflow stimulate the release of molecules from the nanofibers. To expand thepotential applications of the biomimetic platform, the photothermal responsiveness to reach the typical temperature level forperforming photothermal therapy (PTT) is designed. The on-demand drug model penetration into pig tissue demonstrates theefficiency of the nanostructured platform in the rapid and controlled release of molecules, while the high biocompatibility confirmsthe pillow potential for biomedical applications based on the NIR light-driven multitherapy strategy.

Keywords:
bioinspired materials, NIR-light responsive nanomaterials, multifunctional platforms, electrospun nanofibers, plasmonic hydrogel, photothermal-based polytherapy, on-demand drug delivery

Abstract:
This work describes the morphological, optical, and thermo‐optical properties of a temperature‐sensitive hydrogel poly(N‐isopropylacrylamide‐co‐N‐isopropylmethacrylamide) [P(NIPAm‐co‐NIPMAm]) film containing a specific amount of gold nanorods (GNRs). The light‐induced thermoplasmonic heating of GNRs is used to control the optical scattering of an initially transparent hydrogel film. A hydrated P(NIPAm‐co‐NIPMAm) film is optically clear at room temperature. When heated to temperatures over 37 °C via light irradiation with a resonant source (λ = 810 nm) to the GNRs, a reversible phase transition from a swollen hydrated state to a shrunken dehydrated state occurs. This phenomenon causes a drastic and reversible change in the optical transparency from a clear to an opaque state. A significant red shift (≈30 nm) of the longitudinal band can also be seen due to an increased average refractive index surrounding the GNRs. This change is in agreement with an ad hoc theoretical model which uses a modified Gans theory for ellipsoidal nanoparticles. Morphological analysis of the composite film shows the presence of well‐isolated and randomly dispersed GNRs. Thermo‐optical experiments demonstrate an all‐optically controlled light attenuator (65% contrast ratio) which can be easily integrated in several modern optical applications such as smart windows and light‐responsive optical attenuators.

Keywords:
active plasmonics, gold nanorods, hydrogels, optical attenuators, optical transparency, plasmonic nanoparticles, polymers

Abstract:
Polyvinylidene fluoride (PVDF) is one of the most important piezoelectric polymers. Piezoelectricity in PVDF appears in polar β and ɣ phases. Piezoelectric fibers obtained by means of electrospinning may be used in tissue engineering (TE) as a smart analogue of the natural extracellular matrix (ECM). We present results showing the effect of rotational speed of the collecting drum on morphology, phase content and in vitro biological properties of PVDF nonwovens. Morphology and phase composition were analyzed using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR), respectively. It was shown that increasing rotational speed of the collector leads to an increase in fiber orientation, reduction in fiber diameter and considerable increase of polar phase content, both b and g. In vitro cell culture experiments, carried out with the use of ultrasounds in order to generate electrical potential via piezoelectricity, indicate a positive effect of polar phases on fibroblasts. Our preliminary results demonstrate that piezoelectric PVDF scaffolds are promising materials for tissue engineering applications, particularly for neural tissue regeneration, where the electric potential is crucial.

Keywords:
scaffolds, electrospinning, polyvinylidene fluoride, tissue engineering

Abstract:
Body tissues and organs have complex functions which undergo intrinsic changes during medical treatments. For the development of ideal drug delivery systems, understanding the biological tissue activities is necessary to be able to design materials capable of changing their properties over time, on the basis of the patient's tissue needs. In this study, a nanofibrous thermal‐responsive drug delivery system is developed. The thermo‐responsivity of the system makes it possible to self‐regulate the release of bioactive molecules, while reducing the drug delivery at early stages, thus avoiding high concentrations of drugs which may be toxic for healthy cells. A co‐axial electrospinning technique is used to fabricate core–shell cross‐linked copolymer poly(N‐isopropylacrylamide‐co‐N‐isopropylmethacrylamide) (P(NIPAAm‐co‐NIPMAAm)) hydrogel‐based nanofibers. The obtained nanofibers are made of a core of thermo‐responsive hydrogel containing a drug model, while the outer shell is made of poly‐l‐lactide‐co‐caprolactone (PLCL). The custom‐made electrospinning apparatus enables the in situ cross‐linking of P(NIPAAm‐co‐NIPMAAm) hydrogel into a nanoscale confined space, which improves the electrospun nanofiber drug dosing process, by reducing its provision and allowing a self‐regulated release control. The mechanism of the temperature‐induced release control is studied in depth, and it is shown that the system is a promising candidate as a "smart" drug delivery platform.

Keywords:
biomimetic nanomaterials, electrospun core–shell nanofibers, hierarchical nanostructures, smart drug delivery, thermo‐responsive hydrogels

Abstract:
Development of hybrid scaffolds and their formation methods occupies an important place in tissue engineering. In this paper, a novel method of 3D hybrid scaffold formation is presented as well as an explanation of the differences in scaffold properties, which were a consequence of different crosslinking mechanisms. Scaffolds were formed from 3D freeze-dried gelatin and electrospun poly(lactide-co-glicolide) (PLGA) fibers in a ratio of 1:1 w/w. In order to enhance osteoblast proliferation, the fibers were coated with hydroxyapatite nanoparticles (HAp) using sonochemical processing. All scaffolds were crosslinked using an EDC/NHS solution. The scaffolds' morphology was imaged using scanning electron microscopy (SEM). The chemical composition of the scaffolds was analyzed using several methods. Water absorption and mass loss investigations proved a higher crosslinking degree of the hybrid scaffolds than a pure gelatin scaffold, caused by additional interactions between gelatin, PLGA, and HAp. Additionally, mechanical properties of the 3D hybrid scaffolds were higher than traditional hydrogels. In vitro studies revealed that fibroblasts and osteoblasts proliferated and migrated well on the 3D hybrid scaffolds, and also penetrated their structure during the seven days of the experiment.

Keywords:
hybrid scaffolds, electrospinning, freeze-drying, gelatin, hydroxyapatite, sonochemical covering/grafting

Abstract:
A surface of polymeric nonwovens may be coated with various types of nanoparticles for medical applications, filtration, and so forth. However, quite often methods used for surface modification are difficult to scale up or are not applicable for polymers. In this article, we present one-step process enabling nonwovens functionalization. Poly(l-lactide-co-glicolide) (PLGA) nonwovens were prepared by electrospinning process and coated with hydroxyapatite nanoparticles (HAp) using ultrasonic processing. The effect of the process was evaluated with various techniques. HAp layer was successfully attached without loss of structural properties of HAp or PLGA nonwovens. The analysis confirmed the decrease of hydrophobicity of coated nonwoven, as well as its biocompatibility, making this material valuable from the perspective of medical applications. The sonochemical functionalization of polymeric nonwovens may be considered as an effective and economic method, enhancing surface properties of electrospun nonwovens for various applications.

Keywords:
lectrospinning, fibrous composites, nanoparticles, surface modification, ultrasonic treatment

Abstract:
Despite progress which has been made in recent years in the field of cell-based therapies or cell scaffolds for cartilage regeneration, a lot of work still needs to be done. Scaffolds remain a great base for tissue regeneration. However, proper implantation procedures or post-treatment still await development. In this review we summarize paths of cartilage treatment, especially focusing on cell scaffold design and manufacture. As well as the advantages and disadvantages of available or investigated methods and materials, especially focusing on cartilage scaffold design. We show the most promising directions and barriers in the creation of healthy tissue.

Keywords:
cartilage regeneration, medical devices, scaffold development, tissue engineering

Abstract:
Materials for the treatment of cancer have been studied comprehensively over the past few decades. Among the various kinds of biomaterials, polymer-based nanomaterials represent one of the most interesting research directions in nanomedicine because their controlled synthesis and tailored designs make it possible to obtain nanostructures with biomimetic features and outstanding biocompatibility. Understanding the chemical and physical mechanisms behind the cascading stimuli-responsiveness of smart polymers is fundamental for the design of multifunctional nanomaterials to be used as photothermal agents for targeted polytherapy. In this review, we offer an in-depth overview of the recent advances in polymer nanomaterials for photothermal therapy, describing the features of three different types of polymer-based nanomaterials. In each case, we systematically show the relevant benefits, highlighting the strategies for developing light-controlled multifunctional nanoplatforms that are responsive in a cascade manner and addressing the open issues by means of an inclusive state-of-the-art review. Moreover, we face further challenges and provide new perspectives for future strategies for developing novel polymeric nanomaterials for photothermally assisted therapies.

Abstract:
Physical and chemical factors resulting from the sterilization methods may affect the structure and properties of the materials which undergo this procedure. Poly(l-lactide-co-glicolide) (PLGA) is commonly used for medical applications, but, due to its inadequate mechanical properties, it is not recommended for load-bearing applications. One of the methods for improving PLGA mechanical properties is addition of hydroxyapatite nanoparticles (nHAp). The aim of this study was to evaluate the effect of nanoparticles addition on PLGA structure and properties after gamma radiation. According to our results, reduction of the molecular mass caused by gamma radiation was lower for PLGA with nHAp addition. Differential scanning calorimetry (DSC) analysis indicates an increase of crystallinity caused both by nHAp and gamma radiation. The first phenomenon can be explained by heteronucleation, while the second one is most probably related to higher molecular mobility of degrading polymer. Moreover, addition of nanoparticles increases thermal stability and affects the Young's modulus changes after gamma radiation.

Abstract:
Highly efficient single-material organic solar cells (SMOCs) based on fullerene-grafted polythiophenes were fabricated by incorporating electrospun one-dimensional (1D) nanostructures obtained from polymer chain stretching. Poly(3-alkylthiophene) chains were chemically tailored in order to reduce the side effects of charge recombination which severely affected SMOC photovoltaic performance. This enabled us to synthesize a donor–acceptor conjugated copolymer with high solubility, molecular weight, regioregularity, and fullerene content. We investigated the correlations among the active layer hierarchical structure given by the inclusion of electrospun nanofibers and the solar cell photovoltaic properties. The results indicated that SMOC efficiency can be strongly increased by optimizing the supramolecular and nanoscale structure of the active layer, while achieving the highest reported efficiency value (PCE = 5.58%). The enhanced performance may be attributed to well-packed and properly oriented polymer chains. Overall, our work demonstrates that the active material structure optimization obtained by including electrospun nanofibers plays a pivotal role in the development of efficient SMOCs and suggests an interesting perspective for the improvement of copolymer-based photovoltaic device performance using an alternative pathway.

Abstract:
The aim of this research was to study the effect of charge polarity applied to the spinning nozzle on the structure and properties of polycaprolactone/chitosan (PCL/CHT) blends, in particular the efficiency of further surface modification by chondroitin sulphate (CS). The observed differences in the morphology and properties of fibres formed at different polarities were interpreted in terms of molecular interactions occurring in the system. FTIR results indicate stronger PCL-chitosan interactions at negative polarity, resulting in lower PCL crystallinity and crystal size distribution determined by DSC, as well as lower wettability. The charge polarity influences PCL/CHT fibre morphology and tailors some of their properties, e.g. wettability, mechanical properties and the efficiency of surface modification. Better efficiency of CS attachment was observed at negative polarity using atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) is most probably related to higher chitosan content at the fibres' surface being attracted by the negative external potential.

Keywords:
Polycaprolactone/chitosan nanofibres, Charge potential effect in electrospinning, Polycaprolactone-chitosan interactions

Abstract:
Electrospinning of chitosan blends is a reasonable idea to prepare fibre mats for biomedical applications. Synthetic and natural components provide, for example, appropriate mechanical strength and biocompatibility, respectively. However, solvent characteristics and the polyelectrolyte nature of chitosan influence the spinnability of these blends. In order to compare the effect of solvent on polycaprolactone/chitosan fibres, two types of the most commonly used solvent systems were chosen, namely 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and acetic acid (AA)/formic acid (FA). Results obtained by various experimental methods clearly indicated the effect of the solvent system on the structure and properties of electrospun polycaprolactone/chitosan fibres. Viscosity measurements confirmed different polymer–solvent interactions. Various molecular interactions resulting in different macromolecular conformations of chitosan influenced its spinnability and properties. HFIP enabled fibres to be obtained whose average diameter was less than 250 nm while maintaining the brittle and hydrophilic character of the nonwoven, typical for the chitosan component. Spectroscopy studies revealed the formation of chitosan salts in the case of the AA/FA solvent system. Chitosan salts visibly influenced the structure and properties of the prepared fibre mats. The use of AA/FA caused a reduction of Young's modulus and wettability of the proposed blends. It was confirmed that wettability, mechanical properties and the antibacterial effect of polycaprolactone/chitosan fibres may be tailored by selecting an appropriate solvent system. The MTT cell proliferation assay revealed an increase of cytotoxicity to mouse fibroblasts in the case of 25% w/w of chitosan in electrospun nonwovens.

Keywords:
chitosan, electrospinning, PCL/chitosan fibres, solvent system, chitosan salts

Abstract:
MXene, a recently-discovered family of two-dimensional (2 D) transition metal carbides and/or nitrides, have attracted much interest because of their unique electrical, thermal, and mechanical properties. In this study, poly(acrylic acid) (PAA), polyethylene oxide (PEO), poly(vinyl alcohol) (PVA), and alginate/PEO were electrospun with delaminated Ti3C2 (MXene) flakes. The effect of small additions of delaminated Ti3C2 (1% w/w) on the structure and properties of the nanofibers were investigated and compared with those of the neat polymer nanofibers using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). Ti3C2 had an effect on the solution properties of the polymer and a greater effect on the average fiber diameter. The Ti3C2Tx/PEO solution exhibited the largest change in viscosity and conductivity with an 11% and 73.6% increase over the base polymer, respectively. X-ray diffractograms demonstrated a high degree of crystallization for Ti3C2/PEO and a slight decrease in crystallinity for Ti3C2/PVA.

Keywords:
composite nanofibers, electrospinning, MXene

Abstract:
Pulsatile drug delivery systems are gaining a lot of interest because of their numerous advantages, especially when compared to conventional pharmaceutical dosage forms [1]. These materials are time- and site-specific drug delivery systems which can minimize deleterious side effects of conventional drug administration systems. Nevertheless, the delivery systems that are of particular interest are the ones with reversible on-off switching capability, because they allow the delivery of therapeutic agents at the proper time after a predetermined lag time. Among the polymers used for biomedical applications, hydrogels are a class of materials of particular significance, because they can provide spatial and temporal control over the release of various types of drugs. Stimuli-responsive hydrogels can release drugs on-demand with a fast release rate through different mechanisms. The effectiveness of this process can be maximized using nanostructured materials with a large surface-area-to-volume ratio such as electrospun nanofibers. Current challenges in the development of hydrogel electrospun fibrous nanomaterials lie in the lack of spinnability of pure hydrogel precursor solutions. Addressing this issue, we firstly designed a new core-shell nanofibrous material in which the poly(N-isopropylacrylamide)-derivative hydrogel is confined within a shell of a spinnable polymer (Figure 1a). Alternatively, we developed a scaffold material in which electrospun nanofibers loaded with different bioactive molecules where surrounded by a stimuli-responsive hydrogel (Figure 1b). Morphological and chemical characterization as well as drug release studies were carried out to confirm the material’s ability to supply different doses of drugs on demand and to study the release mechanism.

Abstract:
Single-material organic solar cells (SMOCs) based on fullerene-grafted polythiophenes are considered promising devices for organic solar cells (OSCs). The main efforts in this field focus on the chemical tailoring of polymer molecules to reduce the side effects of charge recombination. These advances have made it possible to obtain a power conversion efficiency (PCE) close to conventional bulk heterojunction (BHJ) cells. So far, however, SMOCs still show inadequate efficiencies due to ineffective charge transport. Here we show how SMOC efficiency can be strongly increased by optimizing the supramolecular and nanoscale structure of the active layer, while achieving the highest reported efficiency value (PCE = 5.58%) [1]. The enhanced performance may be attributed to well-packed and properly oriented polymer chains. The hierarchical structure is given by the incorporation of electrospun one-dimensional nanostructures obtained from polymer chain stretching. Our results suggest that the active material optimization obtained by the use of electrospun nanofibers plays a key role in the development of efficient SMOCs.

Abstract:
Stimuli-responsive drug delivery systems are gaining a lot of interest due to their numerous advantages, especially when compared to conventional pharmaceutical dosage forms. One of the examples is photo stimulation that together with nanometer size agents, having high absorption in the near-infrared region, generate heat due to the interaction with light. Stimuli-responsive hydrogels with gold nanorods (AuNRs), that are used as photothermal converters, can aid in releasing drugs on-demand with a fast release rate through different mechanisms. Here we report an easy method for preparing AuNRs encapsulated in a poly(N-isopropylacrylamide) (PNIPAm) hydrogel that release water-soluble drugs due to photo stimulation. PNIPAm-AuNRs demonstrated remote, pulsatile drug release and ex vivo action after irradiation using a NIR laser. Morphological and chemical characterization as well as drug release studies were carried out to confirm the material’s ability to supply different doses of drugs on demand and to study the release mechanism. By combining the photothermal property of AuNRs and thermal-responsive effect of PNIPAm, the hydrogel shows fast thermal/photoresponse, high heating rate, high structural integrity and increased drug release due to phase change mechanism.

Keywords:
drug delivery systems, nanofibers

Abstract:
Intervertebral disc diseases are a significant medical problem affecting many people around the world. In Poland, the statistics of the Social Insurance Institution (Medical Abuse in 2016) indicate that low back pains and other intervertebral disc diseases constitute 17% of the total number of days of sick leave. In connection with the above, current work describes design of a composite scaffold as a carrier in cell therapy, which will contribute to the regeneration of the intervertebral disc, including the increase of its height. Our composite scaffold include nanofibers that were prepared with the use of the electrospinning method. This method is a simple but powerful technique for fabricating desirable nano- and microfibers by using a high potential electric field. Human Mesenchymal stem cells (MSCs) were cultured on the scaffold from poly(L-lactide). Proliferation kits and fluorescence microscopy were used to asses cells’ viability and adherence to the nanofibers’ surface. hMSCs were efficiently cultured on the nanofibrous scaffold. Cells could be readily detected in porous structure of the scaffold after 7 and 14 days of culture. Viability and proliferation kits proved that the material is not toxic. Drug release from nanofibrous material of model growth factor was conducted with pharmacopeia protocols. Drug release of the 14 kDa growth factor was achieved for 14 days without burst release. Nanofibrous biomaterials prove their advances in many tissue engineering applications. Adjustable porosity of the scaffold and the biocompability of biomaterial make it perfect candidate for cells’ scaffold in many medical procedures and also as a drug release carrier. With the use of single nanofibers, such biomaterials can also be readily used in minimally invasive procedures to regenerate IVD.

Keywords:
nanofibers, IVD, MSC

Keywords:
scaffolds, electrospinning, polyvinylidene fluoride, tissue engineering

Keywords:
molecular orientation, scaffolds, fibres, tissue engineering

Abstract:
We used the principles of electrospinning to produce materials for applications in regenerative medicine of urinary bladder wall, ureter, wound dressing and potential applications in cancer therapy. Our research is based on biodegradable polymers produced by ring-opening polymerization. Scaffolds of poly(L-lactide-co-caprolactone) (PLCL) gradually degrade leaving no artificial material behind to be replaced by natural extracellular collagen matrix. We formed flat membranes of micro- and nanofibers to carry out regeneration of urinary bladder wall as animal model of cancer treatment. Grafts were tested for biocompatibility and aimed for guided cell growth, yet we were unsuccessful in mechanical compliance of nanomaterial and reconstructed tissue. We tested tubular scaffolds made of nanofibers aimed for ureter tissue engineering. We found stem cells seeding unnecessary. The results of nanomaterial implantation on animal model were better than for collagen matrices. Animal model was also tested for use of nanofibers of human serum albumin as wound dressing. The native structure of the protein was retained to maintain its anti-adhesive properties, despite poor mechanical characteristics. Nanomaterial caused no inflammation and was resorbed during 16 days. Last application of presented materials was targeted drug delivery system made of PLCL nanofibers. Release of anticancer drug complexed with nanoparticles is to be triggered by tumor cells. Such nanomaterial is potential drug delivery system. Acknowledgements: The authors wishes to thank for the cooperation: T. Chmielewski, P. Nakielski, K. Zembrzycki, G. Mikulowski and prof. T. A. Kowalewski from IPPT PAN. The project was partially supported by the National Centre for Research and Development. Grant No. STRATEGMED1/235368/8/NCBR/2014.

Keywords:
electrospinning, nanofibers, regenerative medicine, wound dressing, urology, biodegradable polymers, animal model.

Keywords:
chitosan, PCL, cellular responce, electrospinning

Keywords:
chitozan, polikaprolakton, electrospinning, L929, cytotoksyczność

Keywords:
electrospinning, fibres, surface, chitosan

Abstract:
Bicomponent poly(caprolactone)/ chitosan (PCL/Chit) nanofibers are a promising alternative for cartilage tissue regeneration. Chitosan is characterized by high structural similarity to the glycosaminoglycans (GAG) which naturally occur in the extracellular matrix (ECM). Its hydrophilicity is beneficial for cells adhesion and proliferation [1]. The amino groups in chitosan are responsible for the formation of polycations, which subsequently form compounds with natural and synthetic anions (proteins, lipids, synthetic polymers which are negatively charged) [2, 3]. Electrospinning of polycations with positive charge on the needle, is difficult due to the instability of the stream resulting from large repulsion force in the polymer jet [3]. Introduction of synthetic polymer molecules to the solution decreases interactions between the chains of chitosan and reduces the viscosity of the solution, so they are easier to form by electrospinning, as well as with negative charge on the needle [4 ]. A synthetic polymer, which is poly(caprolactone), improves mechanical properties of the fibers and the time of the hydrolytic degradation of the scaffold [4]. Nanofibers are excellent material for cell scaffolds used in tissue engineering because of high similarity of their morphology to native extracellular matrix (ECM) [1, 2]. From the viewpoint of cartilage tissue regeneration scaffold in the form of nanofibers is particularly justified due to naturally occurring network of polymer fibers (proteins and glycosaminoglycans) called aggrecans, in ECM of cartilage. Chondrocytes are connected with aggrecans [4]. Both, the structure and composition of formed nanofibers may affect the time in which cells will reach their proper morphology and undertake its functions [4]. In order to study cell behavior on electrospun PCL/chitosan nonwoven, fibroblasts L929 were cultured. Actin Green staining was conducted in order to imagine actin cytoskeleton of fibroblasts. To characterize, both fibers structure and cell morphology, SEM imagining was done. AFM imaging was carried to describe fibers topography and phase distribution. Also conductivity and viscosity of the PCL/chitosan solution with various polymer ratio was measured.

Keywords:
electrospinninig, scaffolds, PCL, chitozan, cellular responce

Abstract:
Influence of the crystallinity of the substrate on cell proliferation during in-vitro study was highlighted in few articles. Methods of forming 3-D scaffolds usually do not take into account crystallinity optimisation. The aim of proposed presentation is to investigate an influence of polycaprolactone (PCL) crystallinity on cells spreading, their activity and proliferation. PCL Mn 45k and Mn 80k g/mol were used. As a solvents: HFIP (H) and Acetic Acid (AA) were used. Two methods of foil preparation were analysed: -forming from melt (PCL45, PCL80) -forming from 10%wt solution (e.g. PH45, PAA45) Samples were analyzed using interfered-polarization microscopy (MIP) which allows to describe the morphology of spherolites (crystalline and amorphous phase). Degree of crystallinity was analysed by differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). Selected samples surfaces were O2 plasma treated to decrease hydrophobic properties of PCL. L929 cells adhesion and morphology were analyzed by immunohistochemical staining for actin and nuc lei. Cell activity and proliferation were analyzed. Morphology of spherolites was analyses using interfered-polarization microscopy (MIP). Analyses indicate changes in spherolites shape, size and also crystalline/ amorphous phase amount. Differences of crystallinity for PCL using different molecular weight were analysed by DSC and WAXS measurements. Decrease of contact angle was observed for O2 plasma treated samples. All PCL films were found as nontoxic for L929 cells. Differences in cells spreading, activity and proliferation degree were found. Modification of Mn, solvent and concentration of PCL enable film formation in wide range of crystallinity. L929 during in-vitro study interact with the PCL film. Crystallinity as part of the supermolecular structure influence on cells morphology.

Keywords:
crystallinity, PCL, cellular responce, structure