The Influence of Graphene Content on the Antibacterial Properties of Polycaprolactone.

This work contains an analysis of the impact of modifying a bioresorbable polymer-polycaprolactone (PCL)-with various additives on its antibacterial properties. To this end, samples of PCL filament containing various content levels of graphene (GNP), 0.5%, 5%, 10%, were obtained using injection molding. Polymer samples without additives were used for comparison. The next step was to assess the antimicrobial impact of the preparations under study against the following microorganisms: Staphylococcus aureus ATCC 25293, Escherichia coli ATCC 25922, Candida albicans ATCC 10231. Effective bactericidal activity of PCL with small amount of GNP, especially against C. albicans and S. aureus was confirmed. A decrease in this property or even multiplication of microorganisms was observed in direct proportion to the graphene content in the samples.

Electrospun polycaprolactone membranes with Zn-doped bioglass for nasal tissues treatment.

In this work, composite membranes were investigated as future components of a layered implant for the reconstruction of nasal septum. Incorporation of zinc ions into nasal implants could potentially provide antibacterial properties to decrease or eliminate bacterial infections and subsequent surgical complications. Two types of membranes were prepared using an electrospinning method: PCL with bioglass and PCL with bioglass doped with Zn. The aim of this work was to investigate the influence of bioglass addition on the morphology, fiber diameter and composition of the membranes. The apatite-forming ability was examined in Simulated Body Fluid (SBF). The cytotoxicity of the membranes, ALP activity and in vitro mineralization were evaluated in cell culture. The mineralization and ALP activity was higher for polycaprolactone membranes modified with Zn doped bioglass than compared to pure PCL membranes or control material. The results proved that the presence of Zn2+ in the electrospun membranes = influence the osteogenic differentiation of cells.

Bioactive nanocomposite PLDL/nano-hydroxyapatite electrospun membranes for bone tissue engineering.

New nanocomposite membranes with high bioactivity were fabricated using the electrospinning. These nanocomposites combine a degradable polymer poly(L/DL)-lactide and bone cell signaling carbonate nano-hydroxyapatite (n-HAp). Chemical and physical characterization of the membranes using scanning electron microscopy, Fourier transform infrared spectroscopy and the wide angle X-ray diffraction evidenced that nanoparticles were successfully incorporated into the fibers and membrane structure. The incorporation of the n-HAp into the structure increased significantly the mineralization of the membrane in vitro. It has been demonstrated that after a 3-day incubation of composite membrane in the Simulated Body Fluid a continuous compact apatite layer was formed. In vitro experiments demonstrated that the incorporation of n-HAp significantly improved cell attachment, upregulated cells proliferation and stimulated cell differentiation quantified using Alkaline Phosphatase and OsteoImage tests. In conclusion, the results demonstrated that the addition of n-HAp provided chemical cues that were a key factor that regulated osteoblastic differentiation.

3D-Printed Polycaprolactone Implants Modified with Bioglass and Zn-Doped Bioglass.

In this work, composite filaments in the form of sticks and 3D-printed scaffolds were investigated as a future component of an osteochondral implant. The first part of the work focused on the development of a filament modified with bioglass (BG) and Zn-doped BG obtained by injection molding. The main outcome was the manufacture of bioactive, strong, and flexible filament sticks of the required length, diameter, and properties. Then, sticks were used for scaffold production. We investigated the effect of bioglass addition on the samples mechanical and biological properties. The samples were analyzed by scanning electron microscopy, optical microscopy, infrared spectroscopy, and microtomography. The effect of bioglass addition on changes in the SBF mineralization process and cell morphology was evaluated. The presence of a spatial microstructure within the scaffolds affects their mechanical properties by reducing them. The tensile strength of the scaffolds compared to filaments was lower by 58-61%. In vitro mineralization experiments showed that apatite formed on scaffolds modified with BG after 7 days of immersion in SBF. Scaffold with Zn-doped BG showed a retarded apatite formation. Innovative 3D-printing filaments containing bioglasses have been successfully applied to print bioactive scaffolds with the surface suitable for cell attachment and proliferation.

Injection Molding Process Simulation of Polycaprolactone Sticks for Further 3D Printing of Medical Implants.

The aim of the present study was a simulation of the injection molding process of polycaprolactone filament sticks for further 3D printing of osteochondral implants. Polycaprolactone data are not available in the data banks of popular injection molding simulation programs. Therefore, thermal and rheological data from the literature were imported to the material database of Solidworks Plastics software to simulate the injection molding process of filament sticks. The influence of several injection molding parameters including melt temperature, injection time, and injection pressure on the geometry of filament stick (final part) was investigated. Based on the results of the performed simulation and analyses, it was possible to improve the injection process parameters. The accuracy of simulation predictions, based on the literature data, demonstrates the potential of using simulation as a tool to develop polycaprolactone parts for future implants and to optimize the injection molding process.

Newly crosslinked chitosan- and chitosan-pectin-based hydrogels with high antioxidant and potential anticancer activity.

Monoaldehydes, due to natural origin and therapeutic activity, have attracted great attention for their ability to crosslink chitosan hydrogels for biomedical applications. However, most studies have focused on single-component hydrogels. In this work, chitosan-based hydrogels, crosslinked for the first time with 2,3,4-trihydroxybenzaldehyde (THBA), were modified with pectin (PC), bioactive glass (BG), and rosmarinic acid (RA). All of these were not only involved in the crosslinking, but also modulated properties or imparted completely new ones. THBA functioned as a crosslinker, resulting in improved mechanical properties, high swelling capacity and delayed degradation and also imparted high antioxidant activity and antiproliferative effect on cancer cells without cytotoxicity for normal cells. Hydrogels containing PC showed enhanced mechanical strength, while the combination with BG gave improved stability in PBS. All hydrogels modified with BG exhibited the ability to mineralise in SBF. The addition of RA enhanced antioxidant and anticancer activities and promoting the mineralisation process.

Conductive Polyaniline Patterns on Electrospun Polycaprolactone/Hydroxyapatite Scaffolds for Bone Tissue Engineering.

Currently, the challenge for bone tissue engineering is to design a scaffold that would mimic the structure and biological functions of the extracellular matrix and would be able to direct the appropriate response of cells through electrochemical signals, thus stimulate faster bone formation. The purpose of the presented research was to perform and evaluate PCL/n-HAp scaffolds locally modified with a conductive polymer-polyaniline. The material was obtained using electrospinning, and a simple ink-jet printing method was applied to receive the conductive polyaniline patterns on the surface of the electrospun materials. The samples of scaffolds were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal analysis (DSC, TGA), and infrared spectroscopy (FTIR) before and after immersion of the material in Simulated Body Fluid. The effect of PANI patterns on changes in the SBF mineralization process and cell morphology was evaluated in order to prove that the presented material enables the growth and proliferation of bone cells.

Analysis of the antibacterial properties of polycaprolactone modified with graphene, bioglass and zinc-doped bioglass.

PURPOSE: Innovative biomedical filaments for 3D printing in the form of short and biodegradable composite sticks modified with various additives were used to prepare biomaterials for further nasal implants. As the respiratory tract is considered to be potentially exposed to contamination during the implantation procedure there is a need to modify the implant with an antibacterial additives. The purpose of this work was to analyze the effect of biodegradable polymer - polycaprolactone (PCL) modification with various additives on its antibacterial properties. METHODS: PCL filament modified with graphene (0.5, 5, 10% wt.), bioglass (0.4% wt.) and zinc-doped bioglass (0.4% wt.) were used to print spatial biomaterials using FDM 3D printer. Pure polymer biomaterials without additives were used as reference samples. The key task was to assess the antimicrobial impact of the prepared biomaterials against the following microorganisms: Staphylococcus aureus ATCC 25293, Escherichia coli ATCC 25922, Candida albicans ATCC 10231. RESULTS: The research results point to a significant antibacterial efficacy of the tested materials against S. aureus and C. albicans, which, however, seems to decrease with increasing graphene content in the filaments. A complete lack of antibacterial efficacy against E. coli was determined. CONCLUSIONS: The tested biomaterials have important antibacterial properties, especially against C. albicans. The obtained results showed that biomaterials made of modified filaments can be successfully used in implantology, where a need to create temporary tissue scaffolds occurs.

Biomaterials in the Reconstruction of Nasal Septum Perforation.

INTRODUCTION: Septal perforations are among the most common craniofacial defects. The causes of septal perforations are varied. OBJECTIVES: The purpose of the study was to develop a septal cartilage implant biomaterial for use in the reconstruction of nasal septal perforations and prepare personalized implants for each patient individually using 3D printing technology. METHODS: Fragments of septal nasal cartilage from 16 patients undergoing surgery for a deviated nasal septum were analyzed to establish microfeatures in individual samples. A scanning electron microscope was used to estimate the microstructure of the removed septal cartilage. 3D models of porous scaffolds were prepared, and a biomaterial was fabricated in the shape of the collected tissue using a 3D printer. RESULTS: Of the various materials used in the Fused Deposition Modeling (FDM) technology of 3D printing, PLLA was indicated as the most useful to achieve the expected implant features. The implant was designed using the indicated pre-designed shape of the scaffold, and appropriate topography, geometry and pore size were included in the design. CONCLUSIONS: The implant's structure allows the use of this device as a framework to carry nanoparticles (antibiotics or bacteriophages). It is possible to create a porous scaffold with an appropriately matched shape and a pre-designed geometry and pore size to close nasal septal perforations even in cases of large septal cartilage defects.

In vitro and in vivo studies on biocompatibility of carbon fibres.

In the present study we focused on the in vitro and in vivo evaluation of two types of carbon fibres (CFs): hydroxyapatite modified carbon fibres and porous carbon fibres. Porous CFs used as scaffold for tissues regeneration could simultaneously serve as a support for drug delivery or biologically active agents which would stimulate the tissue growth; while addition of nanohydroxyapatite to CFs precursor can modify their biological properties (such as bioactivity) without subsequent surface modifications, making the process cost and time effective. Presented results indicated that fibre modification with HAp promoted formation of apatite on the fibre surface during incubation in simulated body fluid. The materials biocompatibility was determined by culturing human osteoblast-like cells of the line MG 63 in contact with both types of CFs. Both tested materials gave good support to adhesion and growth of bone-derived cells. Materials were implanted into the skeletal rat muscle and a comparative analysis of tissue reaction to the presence of the two types of CFs was done. Activities of marker metabolic enzymes: cytochrome c oxidase (CCO) and acid phosphatase were examined to estimate the effect of implants on the metabolic state of surrounding tissues. Presented results evidence the biocompatibility of porous CFs and activity that stimulates the growth of connective tissues. In case of CFs modified with hydroxyapatite the time of inflammatory reaction was shorter than in case of traditional CFs.

Electrospun polymer scaffolds modified with drugs for tissue engineering.

The purpose of this paper was to fabricate nanofibrous scaffolds containing ossein-hydroxyapatite complex (osteogenon) to mimic the native bone extracellular matrix. Polylactide (PLDL) and polycaprolactone (PCL) were used to prepare scaffolds using electrospinning. Unfortunately, both of these biodegradable polymers have poor cell recognition sites leading to poor cell affinity and adhesion, therefore, based on our previous experience, osteogenon-drug was used at the stage of fibers forming by electrospinning. We have compare the physicochemical parameters and mechanical properties of PLDL/osteo and PCL/osteo scaffolds as well as an osteogenon-drug influence on the microstructure of electrospun materials produced for potential application in bone tissue engineering. We have investigated the effect of the microstructure and the chemical composition of electrospun materials on adhesion, proliferation and morphology as well as on the process of differentiation of bone cells. The use of osteogenon improved mineralization, cell adhesion and the rate of cell differentiation.

An ultrasonic through-transmission technique for monitoring the setting of injectable calcium phosphate cement.

An ultrasound through-transmission method to monitor the setting process of injectable calcium phosphate bone cements in body fluids is presented. This method can be used to determine the acoustic properties of the bone cement as it sets, which are linked to its material properties and provide some information about changes occurring within the cement. The development of the methodology of ultrasonic testing and execution of velocity measurements of the longitudinal and transverse waves using the through-transmission method made it possible to determine the material constants of samples during the setting and hardening process of an injectable cement paste in physiological fluids (i.e. the Young's modulus (E), the Poisson ratio (ν) and the shear modulus (G)), and to determine the degree of anisotropy of wave velocity in the samples. A strong advantage of the proposed method is that it is non-destructive, and the same sample can be used to monitor the whole process of the cement setting. The testing was performed on premixed and injectable calcium phosphate (CPC)/chitosan blend, where glycerol was used as a liquid phase. Comparisons between ultrasonic velocity and empirical tests such as compressive strength, porosity measurement, FTIR, SEM and XRD analysis at different days of immersion in Ringer's solutions showed that the ultrasonic velocity can be very useful to provide in situ information about changes occurring within the cement.

Electrospun gelatin/poly(ε-caprolactone) fibrous scaffold modified with calcium phosphate for bone tissue engineering.

In this study gelatin (Gel) modified with calcium phosphate nanoparticles (SG5) and polycaprolactone (PCL) were used to prepare a 3D bi-layer scaffold by collecting electrospun PCL and gelatin/SG5 fibers separately in the same collector. The objective of this study was to combine the desired properties of PCL and Gel/SG5 in the same scaffold in order to enhance mineralization, thus improving the ability of the scaffold to bond to the bone tissue. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the wide angle X-ray diffraction (WAXD) measurements confirmed that SG5 nanoparticles were successfully incorporated into the fibrous gelatin matrix. The composite Gel/SG5/PCL scaffold exhibited more enhanced mechanical properties than individual Gel and Gel/SG5 scaffolds. The presence of SG5 nanoparticles accelerated the nucleation and growth of apatite crystals on the surface of the composite Gel/SG5/PCL scaffold in simulated body fluid (SBF). The osteoblast response in vitro to developed electrospun scaffolds (PCL and Gel/SG5/PCL) was investigated by using normal human primary NHOst cell lines. NHOst cell culture studies showed that higher alkaline phosphatase (ALP) activity and better mineralization were obtained in the case of composite materials than in pure PCL scaffolds. The mechanically strong PCL scaffold served as a skeleton, while the Gel/SG5 fibers facilitated cell spreading and mineralization of the scaffold.