Indirect Cytotoxicity Test Research Articles

Histopathological and radiological evaluation of the efficacy of hydroxyapatite–boric acid and hydroxyapatite–magnesium coated Kirschner wires on fracture healing in femoral diaphyseal fractures: an experimental study

BackgroundBiomaterials used in fracture healing hold a significant place in orthopedics. This study aimed to develop biomaterials coated with hydroxyapatite (HA), boric acid (BA), and magnesium (Mg) and investigate their effects on fracture healing.MethodsSixty female Wistar Albino rats were included in the study. The subjects were randomized into five groups. Cytotoxicity tests were performed on HA, BA, and Mg, and cell viability rates were calculated. Coatings were applied to Kirschner (K) wires at determined ratios. Group I was the control group with a steel K wire, Group II used HA-coated K wires, Group III used HA + BA-coated K wires, Group IV used HA + BA + Mg-coated K wires, and Group V used HA + Mg-coated K wires. A fracture was induced in the right femur of the subjects, followed by fixation with intramedullary K wires. The subjects were randomly divided into equal numbers and sacrificed at 6 and 12 weeks. Radiological and histopathological evaluations were performed.ResultsIn direct cytotoxicity tests, the highest viability rate was observed in Group IV, while in indirect cytotoxicity tests, it was highest in Group II. In radiological evaluation at the 6th week, the highest scores were in Groups IV and V, while the lowest was in Group III. At the 12th week, the highest scores were in Groups II and V, while the lowest was in Group I. No significant differences were found between the groups (p = 0.837, p = 0.0479). In histopathological evaluation, a significant difference was observed between the groups (p < 0.001), with the highest scores in Group V. A correlation was found between the radiological and histopathological scores (p < 0.001, r = 0.438).ConclusionIt was found that HA + Mg significantly improved histological outcomes in fracture healing. Good histological results can be achieved with the use of Mg-containing implants in both early and late-stage fracture healing. Coating the biomaterials used in fracture fixation with Mg may lead to positive outcomes in fracture healing.

In-Vitro Cytotoxic Evaluation of Titanium Dioxide Nanoparticle Using L929 Cell Lines

ABSTRACT Tooth movement in orthodontic therapy is connected to the frictional force that is created as the wire passes over the bracket. It is possible for teeth to move quickly when friction is at a minimum. Wires coated with nanoparticles have been found to reduce friction as a result of current developments in the orthodontics sector. Having an antimicrobial property is an added benefit. To reduce the friction generated by brackets, wires, and bands by lessening their cytotoxicity, this study examines the potential use of TiO2 nanoparticles in orthodontics. A monolayer of L929 was utilized in an indirect cytotoxicity test to evaluate the cytotoxicity of the coated orthodontic wire. The absence of reactive zones in our sample data demonstrates that TiO2 is not cytotoxic. Considering the results of our study, we conclude that TiO2 is secure for use as a coating for orthodontic devices.

In vitro biodegradation, blood, and cytocompatibility studies of a bioactive lithium silicate glass-ceramic

This study investigates a novel non-stoichiometric lithia-silica glass-ceramic (Bioactive LD) designed for bone tissue engineering applications. Incorporating SiO2–Li2O–CaO–P2O5–K2O–SrO–ZnO, the glass-ceramic underwent optimized thermal treatments resulting in a composition predominantly of lithium disilicate (Li2Si2O5 - 87 %) with a minor lithium phosphate phase (Li3PO4 - 13 %). Structural analysis using X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed a refined microstructure with Li2Si2O5 crystals in rod form with a high aspect ratio of around 4:1. Expanding on previous work, this study investigates the in vitro osteoblastic response of Bioactive LD compared to a commercial glass-ceramic (E-Max CAD®). The evaluation, employing live/dead assays, resazurin assays, and alkaline phosphatase activity measurements at different time points, demonstrated comparable cell viability and proliferation on both glass-ceramics. The chemical stability of the samples was tested, and the Bioactive LD showed a higher amount of leached ions in the solution, without significant mass loss, consistent with the standardized values for a class 4 material (ISO 6872), with no significant change in its microstructure. The chemical solubility tests were investigated employing SEM and energy dispersive X-ray analysis (EDS), giving insights into the role of leached ions in the microstructure and bioactivity of the materials. Notably, Bioactive LD exhibits higher alkaline phosphatase activity, indicating enhanced stimulation of osteoblastic cells. Additionally, the Bioactive LD promotes mineralization matrix production, as evidenced by alizarin red S staining. The study also employs SEM-EDS to evaluate the formation of apatite mineralized matrix. Bioactive LD exhibits a homogeneous mineralized matrix with increased Calcium and Sulfur signals, suggesting early hydroxyapatite formation after Alizarin Red S assay. In contrast, Commercial LD shows limited reactivity and bioactivity, with no substantial calcium deposition. An indirect cytotoxicity test indicates minimal cytotoxicity for Bioactive LD, while Commercial LD exhibits slight cytotoxicity, consistent with findings from the literature. The results highlight Bioactive LD's potential for bone regeneration, emphasizing its enhanced bioactivity and the formation of a complex mineralized matrix that could contribute to improved bone integration properties.

Novel 3D printable PEEK-HA-Mg2SiO4 composite material for spine implants: biocompatibility and imaging compatibility assessments.

To develop a novel 3D printable polyether ether ketone (PEEK)-hydroxyapatite (HA)-magnesium orthosilicate (Mg2SiO4) composite material with enhanced properties for potential use in tumour, osteoporosis and other spinal conditions. We aim to evaluate biocompatibility and imaging compatibility of the material. Materials were prepared in three different compositions, namely composite A: 75 weight % PEEK, 20 weight % HA, 5 weight % Mg2SiO4; composite B: 70 weight% PEEK, 25 weight % HA, 5 weight % Mg2SiO4; and composite C: 65 weight % PEEK, 30 weight % HA, 5 weight % Mg2SiO4. The materials were processed to obtain 3D printable filament. Biomechanical properties were analysed as per ASTM standards and biocompatibility of the novel material was evaluated using indirect and direct cell cytotoxicity tests. Cell viability of the novel material was compared to PEEK and PEEK-HA materials. The novel material was used to 3D print a standard spine cage. Furthermore, the CT andMR imaging compatibility of the novel material cage vs PEEK and PEEK-HA cages were evaluated using a phantom setup. Composite A resulted in optimal material processing to obtain a 3D printable filament, while composite B and C resulted in non-optimal processing. Composite A enhanced cell viability up to ~ 20% compared to PEEK and PEEK-HA materials. Composite A cage generated minimal/no artefacts on CT andMR imaging and the images were comparable to that of PEEK and PEEK-HA cages. Composite A demonstrated superior bioactivity vs PEEK and PEEK-HA materials and comparable imaging compatibility vs PEEK and PEEK-HA. Therefore, our material displays an excellent potential to manufacture spine implants with enhanced mechanical and bioactive property.

Class I Biocompatible DLP-Printed Acrylate Impairs Adhesion and Proliferation of Human Mesenchymal Stromal Cells in Indirect Cytotoxicity Assay.

The popular method of digital light processing 3D printing (DLP) for complex and individual laboratory equipment requires materials that are as inert as possible for use in contact with cells for subsequent investigations. However, the per se incomplete curing of acrylate resins by UV light leaves residuals that are not suitable for cell culture application. Therefore, we evaluated the cytotoxicity of four commercially available acrylate resins with bone marrow-derived human mesenchymal stromal cells (BM-hMSC) in an indirect cytotoxicity test. This involved incubating the printed cylinders in Transwell™ inserts for 7 days. While the degree of crosslinking did not increase significantly between freshly printed and stored samples (3 weeks in ambient conditions), the storage improved the material's performance in terms of cytocompatibility. The DNA amount and LDH activity showed a direct influence of the resin residuals on cell adhesion. The class I acrylate Surgical Guide™ left no adherent cells after 7 days, regardless of previous storage. In comparison, the Basic Ivory™ resin after storage allowed same amount of adherent cells after 7 days as the polystyrene reference. We conclude that resin residuals of certain materials are released, which allows the use of the resins in indirect contact with cells thereafter.

Inkjet Printing of Electrodes on Electrospun Micro- and Nanofiber Hydrophobic Membranes for Flexible and Smart Textile Applications.

With the increasing demand for smart textile and sensor applications, the interest in printed electronics is rising. In this study, we explore the applicability of electrospun membranes, characterized by high porosity and hydrophobicity, as potential substrates for printed electronics. The two most common inks, silver and carbon, were used in inkjet printing to create a conductive paths on electrospun membranes. As substrates, we selected hydrophobic polymers, such as polyimide (PI), low- and high-molecular-weight poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVB) and polystyrene (PS). Electrospinning of PI and PVB resulted in nanofibers in the range of 300-500 nm and PVB and PS microfibers (1-5 μm). The printed patterns were investigated with a scanning electron microscope (SEM) and resistance measurements. To verify the biocompatibility of printed electrodes on the membranes, an indirect cytotoxicity test with cells (MG-63) was performed. In this research, we demonstrated good printability of silver and carbon inks on flexible PI, PVB and PS electrospun membranes, leading to electrodes with excellent conductivity. The cytotoxicity study indicated the possibility of using manufactured printed electronics for various sensors and also as topical wearable devices.

Biocompatibility and Mechanical Properties Evaluation of Ti-6Al-4V Lattice Structures with Varying Porosities

Ti-6Al-4V is one of the popular choices for biomedical implants due to multiple advantages, such as corrosion resistance, high strength-to-weight ratio, biocompatibility, lightweight, durability, and osseointegration properties. However, Young’s modulus (E) of Ti-6Al-4V is much higher than the E of natural human bone, which may lead to stress shielding. Therefore, it is critical that we need to fabricate the implant with specific mechanical properties that can match the patient’s existing bone. With the advent of 3D printing, we now can design porous structures with the most suitable E through adjusting porosity to suit individual needs. Porous structures with various porosities were manufactured by selective laser melting (SLM). Mechanical testing was performed to show that the E of the printed samples was related to the porosities only. Based on the simulated and actual results, there are still many areas that can be improved to enhance the quality of the printed structures. Indirect cytotoxicity tests were performed to verify the biocompatibility of the porous structures.

A biomechanical evaluation on Cubic, Octet, and TPMS gyroid Ti6Al4V lattice structures fabricated by selective laser melting and the effects of their debris on human osteoblast-like cells.

Lattice structures are widely used in orthopedic implants due to their unique features, such as high strength-to-weight ratios and adjustable biomechanical properties. Based on the type of unit cell geometry, lattice structures may be classified into two types: strut-based structures and sheet-based structures. In this study, strut-based structures (Cubic & Octet) and sheet-based structure (triply periodic minimal surface (TPMS) gyroid) were investigated. The biomechanical properties of the three different Ti6Al4V lattice structures fabricated by selective laser melting (SLM) were investigated using room temperature compression testing. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to check the 3D printing quality with regards to defects and quantitative compositional information of 3D printed parts. Experimental results indicated that TPMS gyroid has superior biomechanical properties when compared to Cubic and Octet. Also, TPMS gyroid was found to be less affected by the variations in relative density. The biocompatibility of Ti6Al4V lattice structures was validated through the cytotoxicity test with human osteoblast-like SAOS2 cells. The debris generated during the degradation process in the form of particles and ions is among the primary causes of implant failure over time. In this study, Ti6Al4V particles with spherical and irregular shapes having average particle sizes of 36.5μm and 28.8μm, respectively, were used to mimic the actual Ti6Al4V particles to understand their harmful effects better. Also, the effects and amount of Ti6Al4V ions released after immersion within the cell culture media were investigated using the indirect cytotoxicity test and ion release test.

Corrosion behavior of Mg-Zn-Zr-RE alloys under physiological environment – Impact on mechanical integrity and biocompatibility

Benefits of RE addition on Mg alloys strength and corrosion resistance are widely reported but their effects on biodegradability and biocompatibility are still of concern. This paper investigates the effect of RE additions on biodegradability of Mg-Zn alloys under simulated physiological conditions. In this context, two commercial Mg-Zn-Zr-RE alloys, namely ZE41 and EZ33, with same RE addition but different concentrations are studied in Hank's Balanced Salt Solution (HBSS) at 37 °C and with pH of 7.4. Weight-loss, hydrogen evolution, real-time in-situ drop test, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization are deployed to study corrosion characteristics. The mechanical integrity of both alloys is assessed by mechanical testing post immersion. Furthermore, in vitro biocompatibility is evaluated by indirect cytotoxicity tests using NIH3T3 cells. Results reveal that although both alloys showed similar microstructure, size and distribution of precipitates played a significant role on its corrosion response. EIS and open circuit potential results show stable film formation on EZ33, while ZE41 showed passive layer formation followed by its deterioration, over the analyzed time period. Using real-time drop test, it was shown in ZE41 alloy that both T-phase and Zr-rich precipitates acted as micro cathodes, resulting in an unstable surface film. In EZ33, Zr-rich regions did not influence corrosion response, resulting in better corrosion resistance that was corroborated by post-immersion surface morphology investigations. The higher degradation observed in ZE41 alloy resulted in higher drop in flexural and tensile strength compared to EZ33 alloy. In addition, cytotoxicity tests on NIH3T3 cells revealed that cell viability of EZ33 increased with increasing incubation time, contrary to ZE41, owing to its lower biodegradation behavior and despite higher concentrations of REs. Present results show that an increase in RE concentration in EZ33, relative to ZE41, had a positive effect on corrosion rate that subsequently controlled alloy mechanical integrity and biocompatibility.

In Vitro Direct and Indirect Cytotoxicity Comparative Analysis of One Pre-Hydrated versus One Dried Acellular Porcine Dermal Matrix.

Aim: The aim of the present study was to compare the direct and indirect cytotoxicity of a porcine dried acellular dermal matrix (PDADM) versus a porcine hydrated acellular dermal matrix (PHADM) in vitro. Both are used for periodontal and peri-implant soft tissue regeneration. Materials and methods: Two standard direct cytotoxicity tests—namely, the Trypan exclusion method (TEM) and the reagent WST-1 test (4-3-[4-iodophenyl]-2-[4-nitrophenyl]-2H-[5-tetrazolio]-1,3-benzol-desulphonated)—were performed using human primary mesenchymal stem cells (HPMSCs) seeded directly onto a PDADM and PHADM after seven days. Two standard indirect cytotoxicity tests—namely, lactate dehydrogenase (LTT) and MTT (3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazoliumbromide)—were performed using HPMSCs cultivated in eluates from the matrices incubated for 0.16 h (10 min), 1 h, and 24 h in a serum-free cell culture medium. Results: The WST and the TEM tests revealed significantly lower direct cytotoxicity values of HPMSCs on the PHADM compared with the PDADM. The indirect cytotoxicity levels were low for both the PHADM and PDADM, peaking in short-term eluates and decreasing with longer incubation times. However, they were lower for the PHADM with a statistically significant difference (p < 0.005). Conclusions: The results of the current study demonstrated a different biologic behavior between the PHADM and the PDADM, with the hydrated form showing a lower direct and indirect cytotoxicity.

Solvent-cast direct-writing as a fabrication strategy for radiopaque stents

Bioresorbable stents (BRS) potential in treating coronary heart disease is still to be further developed. Current trends include research with new polymeric materials, the need for thinner struts combined with appropriate mechanical properties, radiopacity and optimized local drug delivery. This work presents a novel solvent-cast direct-write (SC-DW) printing system to manufacture BRS onto a rotating cylinder with poly-l-lactic acid (PLLA) and poly(l-lactic-co-ɛ-caprolactone) (PLCL) inks. Printed stents were characterized in terms of mechanical, thermal and biological properties with human umbilical vein endothelial cells (HUVECs). Expansion assays showed that stents withstood pressures of at least 16 atm and the indirect cytotoxicity test indicated that stents were biocompatible. Polymeric inks were further modified with the addition of 3 radiopaque agents, namely iodine, triiodobenzoic acid (TIBA) and barium sulfate (BaSO4) to render stents radiopaque. Subsequent characterization showed a general increase in strut thickness with respect to control PLLA or PLCL stents, which in turn resulted in higher resistance to compression. Microcomputed tomography was used to assess stents’ radiopacity, showing that TIBA and BaSO4-containing stents presented high X-ray attenuation values and maintained their radiopacity after 3 months incubation time.

Formation and properties of biocompatible Ti-based bulk metallic glasses in the Ti–Cu–Zr–Fe–Sn–Si–Ag system

The Ni-free Ti-based bulk metallic glasses (BMGs) with high glass-forming ability (GFA) can be synthesized in the (Ti, Cu, Zr)92.5Fe2.5Sn2Si1Ag2 alloy system over a wide composition range by copper-mold casting. Especially, the Ti48Cu37Zr7.5Fe2.5Sn2Si1Ag2 glassy alloy can form the BMG rod with a diameter up to 6 mm and showed a high compressive strength of ~ 2.05 GPa, elastic modulus of ~ 100 GPa, and microhardness of ~ 571 Hv. The Ti-based BMGs presented good bio-corrosion resistance in a simulated physiological environment attributed to the formation of Ti-, Zr-, Si-, and Fe-enriched passive films. The biocompatibility of the Ti-based glassy alloys was systematically investigated by both indirect cytotoxicity test and direct cell-culture experiments. The Ti-based BMG extracts had no cytotoxic effects on the proliferation of the cells. The good cell adhesion, proliferation, differentiation, and mineralization of bone-forming MC3T3-E1 pre-osteoblasts on the BMGs were parallel to those on the Ti–6Al–4V alloy. These results manifested that the present Ti-based BMGs are promising candidates as biomaterials.

Evaluation of PVA/Chitosan Cryogels as Potential Tissue Engineering Scaffolds; Synthesis, cytotoxicity and genotoxicity investigations

Cryogelation has become an advantageous method to obtain macro-porous materials with well-defined, interconnected pores for tissue engineering applications. Herein, polyvinyl alcohol and chitosan polymers (PVA-CHI) were used to produce cryogel scaffolds via cryogelation. Glutaraldehyde was used as a crosslinking agent and the effect of crosslinking amount on the properties of scaffolds investigated. Glutaraldehyde amount was divided into 5, 10, and 15% total amount of polymer concentration. The optimized pore morphology was obtained as a scaffold containing 5% glutaraldehyde amount. In addition to the FTIR, SEM, swelling, and degradation analyses, mechanical tests were performed to present the characterization properties of the cryogels. Direct and indirect cytotoxicity test and genotoxicity experiments were performed with Mouse Embryonic Fibroblasts (MEF). In addition, cell morphologies on scaffolds were analyzed with SEM. The results showed that PVA-CHI based cryogels had no genotoxic and cytotoxic effects on MEF cells and have a potential for tissue engineering applications.

Nanocomposite powders of hydroxyapatite-graphene oxide for biological applications

The repair of bone fractures is a clinical challenge for patients with impaired healing, such as osteoporosis. Currently, different strategies have been developed to design new biomaterials, enhancing their interactions with biological systems and conducting the cellular behavior in the desired direction to help fracture healing. In the present work, hydroxyapatite-graphene oxide (HA-GO) nanocomposites were produced and the morphological and physicochemical influences of the addition of 0.5 wt%, 1.0 wt% and 1.5 wt% of GO to HA were observed. FEG-SEM and TEM analyses of HA-GO nanocomposites showed HA nanoparticles adhered to the surface of the GO sheets, suggesting an effective method to form nanostructured graphene-based biomaterials. As confirmation, physicochemical analyses by Raman, FTIR and TGA demonstrated a strong affinity between HA and GO, according to the increase of concentration from 0.5 wt% to 1.5 wt% GO in the HA-GO nanocomposites. Also, in order to evaluate the HA-GO nanocomposites behavior under biological microenvironment, in vitro bioactivity and indirect cytotoxicity tests were performed. FEG-SEM analyses confirmed the positive results for the bioactivity properties of HA-GO nanocomposite and indirect cytotoxicity demonstrated that even with a decrease in the hDPSCs viability and proliferation, when increasing to 1.5 wt% of GO concentration, high level of cell viability was exhibited by HA-GO nanocomposites. These biological results suggested the 0.5 wt% HA-GO nanocomposite as a potential bioactive bone graft and a promising biomaterial for bone tissue regeneration, when compared to the pure HA.

Preparation of hybrid PU/PCL fibers from steviol glycosides via electrospinning as a potential wound dressing materials

AbstractIn this study, the synthesis and application of biocompatible steviol glycosides based polyurethane/poly (ε‐caprolactone) (PU/PCL) fibers was performed by electrospinning as a potential wound dressing materials that can be used for the closure of nonhealing wounds. During electrospinning, steviol glycoside‐based polyurethane structures were used in blend formation with poly (ε‐caprolactone) for easy producibility. Steviol glycosides are a natural abundant and easily accessible source as the main component of the wound dressing material due to their free hydroxyl groups, high biocompatibility, and hydrophilicity. The structure of steviol glycosides is composed of saccharide units and the free OH groups. Thus, steviol glycosides act as a crosslinker within the polyurethane structure and provides mechanical strength. For the production of steviol glycosides based PU/PCL fibers first, the steviol glycosides as a monomer were isolated from the stevia rebudiana. Then, polyurethane structures containing stevia glycoside were synthesized with hexamethylene diisocyanate, lactose and PEG‐200 by solution polymerization technique. PCL was added to the prepared polyurethanes in a ratio of 1:2 and formation of nanofiber structure. The prepared wound dressing material was characterized by Fourier transform infrared, atomic force microscopy, and scanning electron microscope techniques. Swelling degree, water content and oxygen permeability assay of the steviol glycosides based PU/PCL wound dressing material was determined. In biocompatibility test, cell viability value of PU/PCL fibrous materials in indirect cytotoxicity test was determined as 86.9% and cell adhesion on hybrid PU/PCL fibers was showed as morphological. In accordance with this target, the steviol glycosides based PU/PCL wound dressing material can be produced easily and low cost. As a result, the wound dressing materials obtained with their high biocompatibility and low costs will be an effective and fast method for the healing of open wounds of diabetics.

Development of Bis-GMA-free biopolymer to avoid estrogenicity

ObjectiveAlthough bisphenol A-glycidyl methacrylate (Bis-GMA)-based dental materials are widely used in dentistry, Estrogenicity from released bisphenol A remains a concern due to possibility of adversely affecting the growth of children and homeostasis of adults. Here, a new family of isosorbide-derived biomonomers were synthesized and experimentally utilized as a matrix of dental sealants to provide physico-mechanical and biological properties comparable to those of a conventional Bis-GMA-based material but without the the potential estrogenicity. MethodsAfter synthesis of isosorbide-derived biomonomers (ISDB) by light polymerization, an experimental dental sealant with different silica filler concentrations (0–15wt%) was characterized and compared to a commercially available Bis-GMA-based sealant. Cytotoxicity and estrogenicity assays were conducted with human oral keratinocytes and estrogen-sensitive MCF-7 cells, respectively. ResultsISDB-based dental sealants exhibited typical initially smooth surfaces with depth of cure, Vickers hardness, compressive strength/modulus, water resorption/solubility, and flowability comparable to those of the commercial sealant and met the ISO standard for dental sealants and polymer-based restorative materials. Indirect cytotoxicity tests using an extract showed comparable viability among experimental ISDB-based materials and a commercial Bis-GMA-incorporated control. DNA synthesis in MCF-7 cells (a marker of estrogenicity) and the release of bisphenol A under enzymatic incubation were not detected in ISDB-based materials. SignificanceIn conclusion, the comparable physico-mechanical properties of ISDB-based materials with their cytocompatibility and lack of estrogenicity suggest the potential usefulness of ISDBs as a newly developed and safe biomaterial.

Photoinactivation of bacteria by hypocrellin-grafted bacterial cellulose

With the aim of developing self-disinfecting materials to prevent pathogen transmission from surfaces to new hosts, here we report a simple and eco-friendly way to prepare photodynamic bacterial cellulose (BC) onto which the naturally-occurring photosensitizer hypocrellin (Hc) has been covalently appended. The resultant hypocrellin-grafted BC membrane (Hc-BC) was characterized by both physical (SEM, TGA, XRD) and spectroscopic (IR, diffuse reflectance UV–visible) methods, and the photosensitizer loading was found to be 155 nmol Hc/mg membrane. Indirect cytotoxicity tests employing mouse skin fibroblast (L929) cells showed no changes in cell viability, demonstrating that the Hc-BC membrane lacked any leachable components (e.g., unreacted coupling agent or hypocrellin) that could be cytotoxic to mammalian cells. The photodynamic antibacterial activity of Hc-BC was evaluated against gram-positive S. aureus (ATCC-6538) and gram-negative E. coli strain 8099. Our results demonstrated a 99.5 + % (2.7 log units) reduction in S. aureus upon illumination (Xe lamp, 65 ± 5 mW/cm2, 420–780 nm; 30 min), however, no statistically significant inactivation of E. coli was observed. Potentiation with potassium iodide was found to increase the antibacterial efficacy of Hc-BC against S. aureus to 99.997% (4.8 log units) at 10 mM KI, while E. coli was inactivated by 99.1% (2 log units) at 100 mM KI, with the increase in inactivation being attributable to short-lived reactive iodide radicals that are the major biocidal agents in the potentiation of Hc-BC by KI. Taken together, our findings demonstrated that hypocrellin-grafted bacterial cellulose is a sustainable material from which potent photodynamic antibacterial materials may be derived.

Preparation, structural and microstructural characterization of Ti-25Ta-10Zr alloy for biomedical applications

Titanium alloys are widely used in the biomedical field due to their good corrosion resistance, high mechanical strength/density ratio, low elastic modulus, and good biocompatibility. With the addition of β-stabilizers elements (such as tantalum), the decrease of the elastic modulus and excellent corrosion resistance are obtained. Zirconium despite being a neutral element appends a good corrosion resistance to titanium alloys. In this paper, Ti-25Ta-10Zr alloy was prepared and characterized aiming biomedical applications. Structural and microstructural analysis corroborated each other and showed the presence of characteristic peaks of three crystalline structures, hexagonal (α phase) and orthorhombic (α’’ phase), dissolved in a matrix with body-centered cubic crystalline structure (β phase). In the indirect cytotoxicity test, no cytotoxic effects were observed on the produced alloy.

Development of bacterial cellulose/alginate/chitosan composites incorporating copper (II) sulfate as an antibacterial wound dressing

Bacterial cellulose (BC) is a biopolymer having unique physical and mechanical properties that widen its usefulness in a diverse range of applications. To be used as a wound dressing however, it lacks natural ability to fight against bacterial infection. To widen its usage as an active wound dressing, BC was incorporated with sodium alginate (AG), chitosan (CS), and copper sulfate (Cu), with an aim of imparting a microstatic or an antimicrobial activity. The structure and properties of the obtained BC/AG/CS-Cu composites were systematically studied. These properties include weight fraction, tensile strength, swelling ratio, and release characteristics of Cu. The obtained BC/AG/CS-Cu composites exhibited antibacterial properties against both gram-positive Methicillin-resistant Staphylococcus aureus (MRSA) and gram-negative bacteria Escherichia coli (E.coli). Moreover, an indirect cytotoxicity test was used to evaluate whether the obtained composites were safe to use in contact with living cells L929 mouse fibroblasts and human dermal fibroblasts. All the results obtained in this work showed that the obtained composites were promising materials to be used as an antimicrobial wound dressing.

Enhanced Structural Stability and Controlled Drug Release of Hydrophilic Antibiotic-Loaded Alginate/Soy Protein Isolate Core-Sheath Fibers for Tissue Engineering Applications

Tissue engineering involves a multifunctional temporary matrix which regulates tissue regeneration through controlled drug release against infections. A nanofibrous core-sheath structured scaffold comprising a tetracycline-loaded alginate/soy protein isolate (TCH-Alg/SPI) as a core and polycaprolactone (PCL) as a sheath was developed using co-axial electrospinning. Coverage of hydrophobic PCL on TCH-Alg/SPI fibers enhanced their structural stability in aqueous solutions as unsheathed fibers rapidly decomposed and provided fast drug release. Core-sheath fibers exhibited an initial burst release at ~49 % after 6 h of immersion in phosphate-buffered saline (PBS) solution and the sustain release reached ~80 % of total loaded drug on day 14. Release characteristics of TCH-Alg/SPI fibers without PCL covering showed immediate drug release within 48 h. Core-sheath fibers investigated by disk diffusion exhibited antibacterial properties against Staphylococcus aureus and Escherichia coli. The non-toxicity of core-sheath fibers was confirmed by an indirect cytotoxicity test using human dermal fibroblasts which showed compatibility and high cell viability of up to 100 % in treated cells. TCH-Alg/SPI-PCL core-sheath fibers show promise as tissue engineering scaffolds which can act as temporary templates for tissue regeneration and exhibit antibiotic release functions against infections caused by pathogenic microorganisms.