Nanoengineered biocomposite tricomponent polymer based matrices for bone tissue engineering

Fabrication and Characterization of a Bioscaffold Using Hydroxyapatite and Unsaturated Polyester Resin

Outstanding biodegradability and biocompatibility are attributes associated with particular polyester substances that make this group useful in specific biomedical fields. To assess the potential as a biomaterial, a novel composite consisting of hydroxyapatite (HAp) and unsaturated polyester resin (UPR) was developed in this work. Using a hand-lay-up technique, various percentages (50, 40, 30, 20, and 10%) of HAp were reinforced into the UPR matrix to fabricate composite materials out of glass sheets. Prior to processing of the composite samples, hydroxyapatite was chemically synthesized in a wet chemical manner. Using a universal testing machine (UTM), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermo-gravimetric analysis (TGA), the fabricated samples were characterized. The crystallographic parameters of synthesized hydroxyapatite (HAp) were also estimated through a range of formulas. The optimal amount for hydroxyapatite was 40% according to the findings of the tensile strength (TS), tensile modulus (TM), percentage of elongation at break (EB), bending strength (BS), and bending modulus (BM). Improvements in TS, TM, BS, and BM for the ideal combination were 39.39, 9.21, 912.05, and 259.96%, in each case, over the controlled one. Thermogravimetric analysis (TGA) has been implemented to determine the degradation temperature of the fabricated composites up to 600 °C.

Ternary MXene-loaded PLCL/collagen nanofibrous scaffolds that promote spontaneous osteogenic differentiation

Conventional bioinert bone grafts often have led to failure in osseointegration due to low bioactivity, thus much effort has been made up to date to find alternatives. Recently, MXene nanoparticles (NPs) have shown prominent results as a rising material by possessing an osteogenic potential to facilitate the bioactivity of bone grafts or scaffolds, which can be attributed to the unique repeating atomic structure of two carbon layers existing between three titanium layers. In this study, we produced MXene NPs-integrated the ternary nanofibrous matrices of poly(L-lactide-co-ε-caprolactone, PLCL) and collagen (Col) decorated with MXene NPs (i.e., PLCL/Col/MXene), as novel scaffolds for bone tissue engineering, via electrospinning to explore the potential benefits for the spontaneous osteogenic differentiation of MC3T3-E1 preosteoblasts. The cultured cells on the physicochemical properties of the nanofibrous PLCL/Col/MXene-based materials revealed favorable interactions with the supportive matrices, highly suitable for the growth and survival of preosteoblasts. Furthermore, the combinatorial ternary material system of the PLCL/Col/MXene nanofibers obviously promoted spontaneous osteodifferentiation with positive cellular responses by providing effective microenvironments for osteogenesis. Therefore, our results suggest that the unprecedented biofunctional advantages of the MXene-integrated PLCL/Col nanofibrous matrices can be expanded to a wide range of strategies for the development of effective scaffolds in bone tissue regeneration.

Determination of the Concentration of Ultrafine Aerosol Using an Ionization Sensor

As public awareness of the threats related to ultrafine aerosols increases, there is a growing need for inexpensive, real-time exposure assessment devices. In this work, the well-established technology used in the smoke detector with a radioactive source was tested in laboratory conditions to check its suitability for determining the number concentration of the ultrafine aerosol. It has been shown that the sensor output changes linearly with the change of diesel soot concentration in the range up to 8.3 × 10⁵ particles cm⁻³. The sensor has also been shown to be able to detect rapid changes in aerosol concentration. Empirical equations describing the influence of air velocity, temperature, relative humidity, and pressure on the sensor output were determined. The collected results confirm that the ionization sensor can be used to assess ultrafine aerosol exposure, although additional engineering work is required to increase the resolution of the output signal measurement and to compensate for the effects of weather conditions. The presented method can be used for concentration monitoring and risk assessment in environmental engineering, materials engineering, cosmetics industry, textiles, sports, chemical, mining, energy, etc.

Electropsun Polycaprolactone Fibres in Bone Tissue Engineering: A Review

Regeneration of bone tissue requires novel load bearing, biocompatible materials that support adhesion, spreading, proliferation, differentiation, mineralization, ECM production and maturation of bone-forming cells. Polycaprolactone (PCL) has many advantages as a biomaterial for scaffold production including tuneable biodegradation, relatively high mechanical toughness at physiological temperature. Electrospinning produces nanofibrous porous matrices that mimic many properties of natural tissue extracellular matrix with regard to surface area, porosity and fibre alignment. The biocompatibility and hydrophilicity of PCL nanofibres can be improved by combining PCL with other biomaterials to form composite scaffolds for bone regeneration. This work reviews the most recent research on synthesis, characterization and cellular response to nanofibrous PCL scaffolds and the composites of PCL with other natural and synthetic materials for bone tissue engineering.

Graphene-based hybrid materials as promising scaffolds for peripheral nerve regeneration

Peripheral nerve injury (PNI) is a serious clinical health problem caused by the damage of peripheral nerves which results in neurological deficits and permanent disability. There are several factors that may cause PNI such as localized damage (car accident, trauma, electrical injury) and outbreak of the systemic diseases (autoimmune or diabetes). While various diagnostic procedures including X-ray, magnetic resonance imaging (MRI), as well as other type of examinations such as electromyography or nerve conduction studies have been efficiently developed, a full recovery in patients with PNI is in many cases deficient or incomplete. This is the reason why additional therapeutic strategies should be explored to favor a complete rehabilitation in order to get appropriate nerve injury regeneration. The use of biomaterials acting as scaffolds opens an interesting approach in regenerative medicine and tissue engineering applications due to their ability to guide the growth of new tissues, adhesion and proliferation of cells including the expression of bioactive signals. This review discusses the preparation and therapeutic strategies describing in vitro and in vivo experiments using graphene-based materials in the context of PNI and their ability to promote nerve tissue regeneration.

Internal nanocrystalline structure and stiffness alterations of electrospun polycaprolactone-based mats after six months of in vitro degradation. An atomic force microscopy assay

Biodegradable electrospun nanofibrous scaffolds for bone tissue engineering applications have been extensively studied as they can provide attractive open-worked architecture resembling natural extracellular matrix, with tunable physical and mechanical properties enhancing positive cellular response. For this purpose, electrospun mats were tested in terms of morphology, mechanical and physical properties, degradation kinetics and related phenomena occurring in micro- and nanoscale. However, detailed description of internal nanostructures of electrospun mats and their changes related to in vitro degradation is still missing. In this manuscript, we report qualitative and quantitative evaluation of internal lamellar nanostructure of electrospun fibrous scaffolds made of pristine polycaprolactone and composite with polymeric matrix and nanoceramic (hydroxyapatite) filler during in vitro degradation. Morphological and mechanical studies performed with an atomic force microscope were followed by scanning electron microscope imaging and X-Ray diffraction. The results suggest degradation-dependent alteration of both organization and thickness of nano-scaled lamellas recorded with atomic force microscope. Moreover, changes of the material's internal structure were followed by enhanced stiffness and higher crystallinity of electrospun fibers.

Alignment and bioactive molecule enrichment of bio-composite scaffolds towards peripheral nerve tissue engineering

Providing topographical cues along with chemical and biological factors is essential for biomimetic scaffolds applied in nerve tissue engineering.

Characterization and influence of hydroxyapatite nanopowders on living cells

Nanomaterials, such as hydroxyapatite nanoparticles show a great promise for medical applications due to their unique properties at the nanoscale. However, there are concerns about the safety of using these materials in biological environments. Despite a great number of published studies of nanoobjects and their aggregates or agglomerates, the impact of their physicochemical properties (such as particle size, surface area, purity, details of structure and degree of agglomeration) on living cells is not yet fully understood. Significant differences in these properties, resulting from different manufacturing methods, are yet another problem to be taken into consideration. The aim of this work was to investigate the correlation between the properties of nanoscale hydroxyapatite from different synthesis methods and biological activity represented by the viability of four cell lines: A549, CHO, BEAS-2B and J774.1 to assess the influence of the nanoparticles on immune, reproductive and respiratory systems.

Fabrication, multi-scale characterization and in-vitro evaluation of porous hybrid bioactive glass polymer-coated scaffolds for bone tissue engineering

Bioactive glass-based scaffolds are commonly used in bone tissue engineering due to their biocompatibility, mechanical strength and adequate porous structure. However, their hydrophobicity and brittleness limits their practical application. In this study, to improve nanomechanical properties of such scaffolds, pure bioactive hybrid glass and two bioactive hybrid glass-polymer coated composites were fabricated. A complementary micro and nanoscale characterization techniques (SEM, AFM, μCT, FTIR, compressive test, goniometer) were implemented for detailed description of architecture and physicochemical properties of hybrid bioactive glass-based scaffolds with emphasis on nano-mechanics. The final step was in-vitro evaluation of three dimensional macroporous structures. Our findings show that after polymer addition, architecture, topography and surface properties of the scaffolds were changed and promoted favoured behaviour of the cells.

Multi-scale characterization and biological evaluation of composite surface layers produced under glow discharge conditions on NiTi shape memory alloy for potential cardiological application

NiTi shape memory alloys are characterized by relatively good biocompatibility primarily thanks to their ability to self-passivate. However, before they can be used as medical implants for long term use, they need to undergo treatment aimed at producing layers on their surface that are superior to spontaneously formed oxide layers and that would increase their resistance to corrosion, limit nickel ion release from the surface (metallosis) and have the capability to shape their biological properties depending on the application. Furthermore, cardiac implants require addressing the issue of blood clotting on the surface. Treatment in glow-discharge low temperature plasma makes it possible to produce titanium layers with a structure and properties that are controlled via process parameters. In addition, antithrombogenic properties can be improved by depositing a carbon coating via the RFCVD process. The aim of the study was to investigate the structure, surface topography, adhesive properties, wettability, surface free energy and evaluate metallosis after producing TiO₂ and a-C:N:H + TiO₂ composite layers on NiTi alloy. The capabilities of AFM microscopes in studying the adhesive properties of a surface were also highlighted in the study. The study shows that the produced surface layers are capable of significantly reducing metallosis. Furthermore, in contrast to NiTi in its initial state, layers of nanocrystalline TiO₂ titanium oxide (rutile) with a homogeneous structure demonstrate greater adhesion strength and more developed surface in the microscale, which facilitates the formation of an a-C:N:H coating. Therefore the formation of a coating of a-C:N:H amorphous carbon on NiTi alloy that has previously been oxidised in low-temperature plasma may prove to be a favourable solution in terms of using NiTi alloy to produce cardiac implants.

The influence of carbon-encapsulated iron nanoparticles on elastic modulus of living human mesenchymal stem cells examined by atomic force microscopy

Nanomaterials and nanoparticles are regarded as promising candidates for various biomedical applications due to their unique physicochemical properties. In this study, three types of carbon-encapsulated iron nanoparticles (CEINs) were synthesized and their impact on cellular changes was investigated by atomic force microscopy (AFM). The AFM experiment was additionally compared with conventional methods, such as colorimetric assay and other microscopic techniques. A significant difference of reduced Young's modulus of the cells was revealed, even at low concentration of nanoparticles in the culture medium. The AFM measurement proved to be a useful tool not only for visualization, but also for identification of local cellular changes at the nanoscale after exposure to carbon-encapsulated iron nanoparticles.

Clinically advancing and promising polymer-based therapeutics

In this review article, we will examine the history of polymers and their evolution from provisional World War II materials to medical therapeutics. To provide a comprehensive look at the current state of polymer-based therapeutics, we will classify technologies according to targeted areas of interest, including central nervous system-based and intraocular-, gastrointestinal-, cardiovascular-, dermal-, reproductive-, skeletal-, and neoplastic-based systems. Within each of these areas, we will consider several examples of novel, clinically available polymer-based therapeutics; in addition, this review will also include a discussion of developing therapies, ranging from the in vivo to clinical trial stage, for each targeted area of treatment. Finally, we will emphasize areas of patient care in need of more effective, accessible, and targeted treatment approaches where polymer-based therapeutics may offer potential solutions.

Nanobead-on-string composites for tendon tissue engineering

The bead-on-string topography of electrospun nanocomposite scaffolds improves fibroblast response in terms of cell spreading and proliferation.

* Engineering Membranes for Bone Regeneration

This review is focused on the use of membranes for the specific application of bone regeneration. The first section focuses on the relevance of membranes in this context and what are the specifications that they should possess to improve the regeneration of bone. Afterward, several techniques to engineer bone membranes by using "bulk"-like methods are discussed, where different parameters to induce bone formation are disclosed in a way to have desirable structural and functional properties. Subsequently, the production of nanostructured membranes using a bottom-up approach is discussed by highlighting the main advances in the field of bone regeneration. Primordial importance is given to the promotion of osteoconductive and osteoinductive capability during the membrane design. Whenever possible, the films prepared using different techniques are compared in terms of handability, bone guiding ability, osteoinductivity, adequate mechanical properties, or biodegradability. A last chapter contemplates membranes only composed by cells, disclosing their potential to regenerate bone.