Biocompatibility Tests Research Articles

Biocompatibility and antioxidant activity of a novel carrageenan based injectable hydrogel scaffold incorporated with Cissus quadrangularis: an in vitro study

BackgroundOver the past years, polysaccharide-based scaffolds have emerged as the most promising material for tissue engineering. In the present study, carrageenan, an injectable scaffold has been used owing to its advantage and superior property. Cissus quadrangularis, a natural agent was incorporated into the carrageenan scaffold. Therefore, the present study aimed to assess the antioxidant activity and biocompatibility of this novel material.MethodsThe present in vitro study comprised of four study groups each constituting a sample of 15 with a total sample size of sixty (n = 60). The carrageenan hydrogel devoid of Cissus quadrangularis acted as the control group (Group-I). Based on the concentration of aqueous extract of Cissus quadrangularis (10% w/v, 20% w/v and 30% w/v) in carrageenan hydrogel, respective study groups namely II, III and IV were considered. Antioxidant activity was assessed using a 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay, whereas the biocompatibility test was performed using a brine shrimp lethality assay. The microstructure and surface morphology of the hydrogel samples containing different concentrations of Cissus quadrangularis aqueous extract was investigated using SEM. One-way ANOVA with the post hoc tukey test was performed using SPSS software v22.ResultsA significant difference (P < 0.05) in the antioxidant activity was observed among the study groups. Group III reported the highest activity, whereas the control group showed the least antioxidant activity. Additionally, a significant (P < 0.01) drop in the antioxidant activity was observed in group IV when compared with group III. While assessing the biocompatibility, a significant (P < 0.001) dose-dependent increase in biocompatibility was observed with the increasing concentration of aqueous extract of Cissus quadrangularis. SEM analysis in group III showed even distribution throughout the hydrogel although the particles are close and densely arranged. Reduced antioxidant activity in group IV was probably due to clumping of the particles, thus reducing the active surface area.ConclusionKeeping the limitations of in vitro study, it can be assumed that a carrageenan based injectable hydrogel scaffold incorporated with 20% w/v Cissus quadrangularis can provide a favourable micro-environment as it is biocompatible and possess better antioxidant property.

Biological test methods for stents: cellular responses to microstructured biomaterials

Abstract One of the greatest challenges in the development of novel implants is to find materials that optimally interact with the tissue and support the function of the implant over a long period of time. Especially considering the fact that biomaterials are used in multiple applications in modern implants, a better understanding of the physiology of the tissue in contact with the material becomes more and more important. To better understand the cellular responses to biomaterials, it is furthermore necessary that the models used reflect the physiological conditions at the implant site. However, in most cases, immortalized cell lines instead of tissue-specific primary cells are used to study the biocompatibility of implant materials. When interpreting these results, it is important to consider that cell lines differ significantly from primary cells found in their native environment. In this study, we examined the morphological differences between a cell line and primary cells upon contact with various implant structures resembling implant prototypes. Using a mouse fibroblast cell line in comparison with primary porcine fibroblasts, we discuss the results with respect to the use of cell lines for biocompatibility testing of biomaterials. Our results suggest that to better estimate meaningful results regarding the compatibility of implant structures, key control experiments should always be performed with specific primary cells.

P12-13 3D reconstructed human cornea-like tissue model as an alternative to animal experiments in the biocompatibility testing of medical devices

P12-13 3D reconstructed human cornea-like tissue model as an alternative to animal experiments in the biocompatibility testing of medical devices

3D-Printed PCL Scaffolds Combined with Juglone for Skin Tissue Engineering

Skin diseases are commonly treated with antihistamines, antibiotics, laser therapy, topical medications, local vitamins, or steroids. Since conventional treatments for wound healing (skin allografts, amnion, xenografts, etc.) have disadvantages such as antigenicity of the donor tissue, risk of infection, or lack of basement membrane, skin tissue engineering has become a popular new approach. The current study presents the design and fabrication of a new wound-dressing material by the addition of Juglone (5-hydroxy-1,4-naphthoquinone) to a 25% Polycaprolactone (PCL) scaffold. Juglone (J) is a significant allelochemical found in walnut trees and, in this study is used as a bioactive material. The effects of different amounts of J (1.25, 2.5, 5, 7.5, and 10 mg) on the biocompatibility, mechanical, chemical, thermal, morphological, and antimicrobial properties of the 3D-printed 25% PCL scaffolds were investigated. The addition of J increased the pore diameter of the 25% PCL scaffold. The maximum pore size (290.72 ± 14 µm) was observed for the highest amount of J (10 mg). The biocompatibility tests on the scaffolds demonstrated biocompatible behavior from the first day of incubation, the 25% PCL/7.5 J scaffold having the highest viability value (118%) among all of the J-loaded scaffolds. Drug release of J into phosphate buffered saline (PBS) at pH 7.4 showed that J was completely released from all 25% PCL/J scaffolds within 7 days of incubation.

Regenerative Medicine to Improve Outcomes of Ventral Hernia Reconstruction (REPAIR Study) Phase 1: Find the Best Decellularization Protocol for the Human Dermis.

Background: Tissue regeneration is a complex process that allows wounds to heal. Many options are currently available to help human skin repair and to reduce the recurrence of hernias. The aim of this study is to analyze the best decellularization protocol for allogenic human dermal tissues. Methods: Dermal flaps from donors were used and compared with a control group. Each flap was subjected to seven different decellularization protocols and washed with a sequence of five solutions. The samples were then subjected to four control tests (such as Nile Red), and long-term contacts were analyzed to assess whether the decellularized dermis samples could support the growth of human fibroblasts. Results: All the samples had an average residual viability of 60%. Except for one sample, the decellularization treatments were able to reduce cell viability significantly. The Nile Red test showed a significant reduction in phospholipid content (mean 90%, p-value < 0.05) in all treatments. The cell growth increased in a linear manner. As described in the literature, sodium-dodecyl-sulfate (SDS) caused an interference between the test and the detergent. Conclusions: This paper shows the first step to finding the best decellularization protocol for allografting human dermal tissues. Further biocompatibility tests and DNA quantification are necessary.

Evaluation of Angiogenesis in an Acellular Porous Biomaterial Based on Polyhydroxybutyrate and Chitosan Using the Chicken Ex Ovo Chorioallantoic Membrane Model.

Simple SummaryThe chorioallantoic membrane (CAM) is an avian extraembryonic membrane widely used as an experimental assay to study angiogenesis and its inhibition in response to tissues, cells, or soluble factors. In recent years, the CAM has become popular in scientific studies focused on the use of its potential for the study of biocompatibility of materials for regenerative strategies and tissue engineering applications. Great research efforts are being made to develop innovative biomaterials able to treat hard tissue defects, including diseases such as a bone cancer. In this article, we describe an approach to detect the formation of blood vessels inside the porous acellular biopolymer polyhydroxybutyrate/chitosan (PHB/CHIT) scaffold using the CAM assay as an in vivo alternative animal model, including macroscopic, histological, immunohistochemical, and molecular evaluation of the biocompatibility.The chorioallantoic membrane (CAM) is a highly vascularized avian extraembryonic membrane widely used as an in vivo model to study angiogenesis and its inhibition in response to tissues, cells, or soluble factors. In recent years, the use of CAM has become an integral part of the biocompatibility testing process for developing biomaterials intended for regenerative strategies and tissue engineering applications. In this study, we used the chicken ex ovo CAM assay to investigate the angiogenic potential of innovative acellular biopolymer polyhydroxybutyrate/chitosan (PHB/CHIT) scaffold, which is intended for the treatment of hard tissue defects, depending on treatment with pro- and anti-angiogenic substances. On embryonic day (ED) 7, the experimental biomaterials were placed on the CAM alone or soaked in vascular endothelial growth factor (VEGF-A), saline solution (PHY), or tyrosine kinase inhibitor (SU5402). After 72 h, the formation of vessels was analyzed in the surrounding area of the scaffold and inside the pores of the implants, using markers of embryonic endothelium (WGA, SNA), myofibroblasts (α-SMA), and macrophages (KUL-01). The morphological and histochemical analysis showed strong angiogenic potential of untreated scaffolds without additional effect of the angiogenic factor, VEGF-A. The lowest angiogenic potential was observed in scaffolds soaked with SU5402. Gene expression of pro-angiogenic growth factors, i.e., VEGF-A, ANG-2, and VE-CAD, was upregulated in untreated scaffolds after 72 h, indicating a pro-angiogenic environment. We concluded that the PHB/CHIT has a strong endogenous angiogenic potential and could be promising biomaterial for the treatment of hard tissue defects.

Exploring the Antibacterial Properties of Lignin-coated Magnetic Nanoparticles Synthesized in a One-pot Process†.

Given the current grave problems with antibiotic resistance, the discovery of novel, unconventional antibacterial drugs is not just important but also urgent. In this contribution, we report on the synthesis and testing of several composite nanomaterials that may find applications as therapeutic drugs or surface disinfectants. These materials are based on magnetic nanostructures coated with lignin, for example, lignin@FeCo. The magnetic properties of these nanocomposites facilitate removal or localization, whereas the lignin shell provides biocompatibility. These nanomaterials are mild antibacterials in the absence of light, but when illuminated become powerful antibacterial agents with typically ≥6 log units of bacterial reduction in 1-5 min of irradiation. These materials are strongly absorbing, including in the very useful NIR biological window, which we illustrate using 810 nm LED irradiation. We also show that in the short time required for antibacterial action, thermal changes are very small (≤5°C). Further, biocompatibility tests using fibroblasts show very limited cell damage and no enhanced adverse effect during 810 nm NIR illumination. As a surface coating for the active material, lignin provides a "trojan horse" strategy to facilitate the antibacterial action.

Review of nickel titanium alloy for orthodontic arch wires

NiTi alloys are in demand in commercial and biomedical industries. This article discusses Ni-Ti alloy characteristics and applications. Ni-Ti is a smart material that can demonstrate thermal-induced shape memory at lower operational temperatures. Its biomedical applications are described. Biomedical industry end products must pass many biocompatibility testing. Biomedical implants must pass haemocompatibility, lysis and thrombogenicity. All the precise approaches and procedures aid with selection.

Wearable adjunct ozone and antibiotic therapy system for treatment of Gram-negative dermal bacterial infection

The problematic combination of a rising prevalence of skin and soft tissue infections and the growing rate of life-threatening antibiotic resistant infections presents an urgent, unmet need for the healthcare industry. These evolutionary resistances originate from mutations in the bacterial cell walls which prevent effective diffusion of antibiotics. Gram-negative bacteria are of special consideration due to the natural resistance to many common antibiotics due to the unique bilayer structure of the cell wall. The system developed here provides one solution to this problem through a wearable therapy that delivers and utilizes gaseous ozone as an adjunct therapy with topical antibiotics through a novel dressing with drug-eluting nanofibers (NFs). This technology drastically increases the sensitivity of Gram-negative bacteria to common antibiotics by using oxidative ozone to bypass resistances created by the bacterial cell wall. To enable simple and effective application of adjunct therapy, ozone delivery and topical antibiotics have been integrated into a single application patch. The drug delivery NFs are generated via electrospinning in a fast-dissolve PVA mat without inducing decreasing gas permeability of the dressing. A systematic study found ozone generation at 4 mg/h provided optimal ozone levels for high antimicrobial performance with minimal cytotoxicity. This ozone treatment was used with adjunct therapy delivered by the system in vitro. Results showed complete eradication of Gram-negative bacteria with ozone and antibiotics typically used only for Gram-positive bacteria, which showed the strength of ozone as an enabling adjunct treatment option to sensitize bacteria strains to otherwise ineffective antibiotics. Furthermore, the treatment is shown through biocompatibility testing to exhibit no cytotoxic effect on human fibroblast cells.

Effect of modified titanium loaded with endothelial progenitor cells-exosomes on osteogenic and angiogenic differentiations of adipose-derived stem cells

To investigate the effects of titanium modified by ultrasonic acid etching/anodic oxidation (UAT) loaded with endothelial progenitor cells-exosome (EPCs-exo) on proliferation and osteogenic and angiogenic differentiations of adipose-derived stem cells (ADSCs). The adipose tissue and bone marrow of 10 Sprague Dawley rats were harvested. Then the ADSCs and EPCs were isolated and cultured by collagenase digestion method and density gradient centrifugation method, respectively, and identified by flow cytometry. Exo was extracted from the 3rd to 5th generation EPCs using extraction kit, and CD9 and CD81 were detected by Western blot for identification. The three-dimensional printed titanium was modified by ultrasonic acid etching and anodic oxidation to prepare the UAT. The surface characteristics of UAT before and after modification was observed by scanning electron microscopy; UAT was placed in EPCs-exo solutions of different concentrations (100, 200 ng/mL), and the in vitro absorption and release capacity of EPCs-exo was detected by BCA method. Then, UAT was placed in DMEM medium containing different concentrations of EPCs-exo (0, 100, 200 ng/mL), and co-cultured with the 3rd generation ADSCs to construct UAT-ADSCs-exo. Cell morphology by laser confocal microscopy, live/dead cell staining, and cell proliferation were observed to evaluate biocompatibility; alkaline phosphatase (ALP) staining and alizarin red staining, RT-PCR detection of osteogenesis-related genes [osteocalcin (OCN), RUNT-related transcription factor 2 (Runx2), ALP, collagen type 1 (COL-1)] and angiogenesis-related gene [vascular endothelial growth factor (VEGF)], immunofluorescence staining for osteogenesis (OCN)- and angiogenesis (VEGF)-related protein expression were detected to evaluate the effect on the osteogenic and angiogenic differentiation ability of ADSCs. Scanning electron microscopy showed that micro-nano multilevel composite structures were formed on the surface of UAT. About 77% EPCs-exo was absorbed by UAT within 48 hours, while EPCs-exo absorbed on the surface of UAT showed continuous and stable release within 8 days. The absorption and release amount of 200 ng/mL group were significantly higher than those of 100 ng/mL group ( P<0.05). Biocompatibility test showed that the cells in all concentration groups grew well after culture, and the 200 ng/mL group was better than the other groups, with fully spread cells and abundant pseudopodia, and the cell count and cell activity were significantly higher than those in the other groups ( P<0.05). Compared with the other groups, 200 ng/mL group showed enhanced ALP activity and mineralization ability, increased expressions of osteogenic and angiogenic genes (OCN, Runx2, COL-1, ALP, and VEGF), as well as increased expressions of OCN and VEGF proteins, with significant differences ( P<0.05). EPCs-exo can effectively promote the adhesion, proliferation, and osteogenic and angiogenic differentiation of ADSCs on UAT surface, the effect is the most significant when the concentration is 200 ng/mL.

An injectable thermosensitive hydrogel for dual delivery of diclofenac and Avastin® to effectively suppress inflammatory corneal neovascularization

Corneal neovascularization (CNV) is a sequela of anterior segment inflammation, which could lead to vision impairment and even blindness. In the present study, the dual delivery of anti-inflammatory agent (i.e., diclofenac; DIC) and anti-VEGF antibody (i.e., Avastin®; Ava) by the thermosensitive hydrogel (Poly(dl-lactide)-poly(ethylene glycol)-poly(dl-lactide); PDLLA-PEG-PDLLA) is expected to effectively inhibit CNV via their synergistic effects. The optimal DIC micelles were formulated and then mixed with Ava and PDLLA-PEG-PDLLA aqueous solution to generate various DIC@Ava-loaded hydrogels. The co-encapsulation of DIC micelles and Ava did not influence the gelling behavior of the system, and the resulting DIC@Ava-loaded hydrogel provided sustained drug release of both DIC and Ava without compromising their pharmacological activity over 19 days. As indicated by in vitro cytotoxicity and in vivo ocular biocompatibility test, the proposed PDLLA-PEG-PDLLA hydrogel caused minimal cytotoxicity against all tested cell lines at a polymeric concentration ranging from 0.05 mg/mL to 0.8 mg/mL and demonstrated good ocular biocompatibility after a single subconjunctival injection. Using the rabbit CNV model, we documented the superior anti-angiogenic effects of the DIC@Ava-loaded hydrogel over Ava alone medication (treatment with Ava solution and Ava-loaded hydrogel) due to synergistic effects of anti-VEGF and anti-inflammatory action. Overall, the proposed DIC@Ava-loaded hydrogel might be a powerful strategy to reduce CNV.

Characterization, antimicrobial and cytotoxic activity of polymer blends based on chitosan and fish collagen

This study aims to produce, characterize, and assess the antimicrobial activity and cytotoxicity of polymer blends based on chitosan (CT) and fish collagen (COL) produced by different precipitation methods. Polymer blends were obtained in alkaline (NaOH), saline (NaCl), and alkaline/saline (NaOH/NaCl) solutions with different CT:COL concentration ratios (20:80, 50:50, and 80:20). The polymer blends were characterized by various physicochemical methods and subsequently evaluated in terms of their in vitro antimicrobial and cytotoxicity activity. In this study, the degree of chitosan deacetylation was 82%. The total hydroxyproline and collagen content in the fish matrix was 47.56 mg. g−1 and 394.75 mg. g−1, respectively. The highest yield was 44% and was obtained for a CT:COL (80:20) blend prepared by precipitation in NaOH. High concentrations of hydroxyproline and collagen in the blends were observed when NaOH precipitation was used. Microbiological analysis revealed that the strains used in this work were sensitive to the biomaterial; this sensitivity was dose-dependent and increased with increasing chitosan concentration in the products. The biocompatibility test showed that the blends did not reduce the viability of fibroblast cells after 48 h of culture. An analysis of the microbiological activity of the all-polymer blends showed a decrease in the values of minimal inhibitory concentration (MIC) and minimal bactericidal concentrations (MBC) for S. aureus and P. aeruginosa. The blends showed biocompatibility with NIH-3T3 murine fibroblast cells and demonstrated their potential for use in biomedical applications such as wound healing, implants, and scaffolds.

Characterization of electrospun fibers and electrospray vancomycin-containing beads through the interstitial or lamellar separation of bead composite fiber membranes to evaluate their biomedical application in vitro

Considering the advantages of electrospun thermoplastic polyurethane (TPU)-fibers and antibiotic (vancomycin)-containing polyvinyl alcohol (PVA)-microbeads for wound dressings, a composite membrane was developed. Electrospun-aligned TPU-fibers were collected using a high-speed drum collector. Three groups of TPU-only, double-sided PVA-microbeads composite TPU-fibers (PVA/TPU/PVA sandwich, DSV40), and simultaneous electrospray PVA-microbeads/electrospun TPU-fibers (interstitial PVA-microbeads, CV40) composite membranes were prepared and characterized. The composites were tested for morphology, infrared spectroscopy, and tensile tests along the fiber-parallel (MD) and fiber-perpendicular (CD) directions, water wettability and absorption, antibacterial activity, and biocompatibility. The results showed that the tensile strength, modulus, and strain of TPU-only in MD and CD directions were 7.31 ± 1.13 and 2.47 ± 0.43 MPa, 2.73 ± 0.36 and 0.69 ± 0.07 MPa and 285.02 ± 23.56 and 360.70 ± 34.01%, respectively. Moreover, MD-direction tensile properties of DSV40 and CV40 resulted in a significant increase in strength (9.05 ± 2.19 and 9.77 ± 1.51 MPa) and modulus (10.97 ± 1.65 and 5.47 ± 0.94 MPa), but a decrease in strain (92.42 ± 11.68 and 185.78 ± 24.85%), compared to TPU-only. However, DSV40 and CV40 showed opposite trends (respective strength of 0.99 ± 0.07 and 2.11 ± 0.33 MPa, modulus of 0.21 ± 0.01 and 0.48 ± 0.51 MPa, and strain of 460.69 ± 29.38 and 435.92 ± 29.26%) in the CD direction compared to TPU-only. In terms of wettability after 10 s observation, DSV40 obtained a hydrophilic tendency (25.91°) than CV40 (74.22°) and TPU-only (121.06°). The results of antibacterial activity showed that both DSV40 and CV40 had good antibacterial effects on Staphylococcus aureus but the inhibitory effect on Escherichia coli was poor. The biocompatibility test confirmed that neither DSV40 nor CV40 negatively affected L929 cell viability.

Cichorium intybus bio-callus synthesized silver nanoparticles: A promising antioxidant, antibacterial and anticancer compound

Cichorium intybus, commonly called chicory, has been widely used as a coffee substitute. It display a wide range of natural compounds and medicinally uses in treatment of gastrointestinal disorders. This study synthesized silver nanoparticles (Ci-AgNPs) using C. intybus leaf-derived callus extract to evaluate phytochemical content, antibacterial, antioxidant and anti-proliferative activities against human breast cancer cells (MDA-MB231). The optimal shape, size and stability of Ci-AgNPs was confirmed using UV–visible spectrophotometry, FESEM, EDX, XRD, DLS, Zeta potential, FTIR and sp-ICP-MS studies. The antibacterial activity of Ci-AgNPs was assessed using disk diffusion method against Staphylococcus aureus and Escherichia coli, and they displayed distinct zones of inhibition. Colorimetric phytochemical analysis of Ci-AgNPs revealed their higher total phenolic (TP) and total flavonoid (TF) content. Ci-AgNPs also indicated a high level of antioxidant activity using FRAP and DPPH assays. The Ci-AgNPs were investigated for their anticancer activities on the cancerous MDA-MB231 cells viability and apoptosis using MTT and flow cytometry, respectively. Ci-AgNPs showed dose dependent cytotoxicity against MDA-MB231 cells with IC50 value of 187.6 μg/mL at 48 h through induction of apoptosis. The biocompatibility test showed that Ci-AgNPs induced neglectable cytotoxicity (lower than 3 %) toward human erythrocytes. This is the first study that reports the bio-callus mediated synthesis of silver nanoparticle using C. intybus callus extract which provided a promising anticancer activity against human breast cancer MDA-MB231 cells and therefore could be used as an alternative and interesting benign strategy for biosynthesis of silver nanoparticles useful in cancer therapy.

Electroconductive, Adhesive, Non-Swelling, and Viscoelastic Hydrogels for Bioelectronics.

As a new class of materials, implantable flexible electrical conductors have recently been developed and applied to bioelectronics. An ideal electrical conductor requires high conductivity, tissue-like mechanical properties, low toxicity, reliable adhesion to biological tissues, and the ability to maintain its shape in wet physiological environments. Despite significant advances, electrical conductors that satisfy all these requirements are insufficient. Herein, a facile method for manufacturing a new conductive hydrogels through the simultaneous exfoliation of graphite and polymerization of zwitterionic monomers triggered by microwave irradiation is introduced. The mechanical properties of the obtained conductive hydrogel are similar to those of living tissue, which is ideal as a bionic adhesive for minimizing contact damage due to mechanical mismatches between hard electronics and soft tissues. Furthermore, it exhibits excellent adhesion performance, electrical conductivity, non-swelling, and high conformability in water. Excellent biocompatibility of the hydrogel is confirmed through a cytotoxicity test using C2C12 cells, a biocompatibility test on rat tissues, and their histological analysis. The hydrogel is then implanted into the sciatic nerve of a rat and neuromodulation is demonstrated through low-current electrical stimulation. This hydrogel demonstrates a tissue-like extraneuronal electrode, which possesses high conformability to improve the tissue-electronics interfaces, promising next-generation bioelectronics applications.

Polycaprolactone/ZnO coating on WE43 magnesium alloy combined with a MgO/MgCO3 transition layer for promoting anticorrosion and interfacial adhesion

Polycaprolactone (PCL) based polymers are usually considered as potential coating materials for improve corrosion resistance of biodegradable magnesium alloy due to excellent mechanical property and biocompatibility. However, as for the quality and stability of the polymer-based coatings, the interfacial adhesion of polymer coating to magnesium substrate and the antibacterial ability should not be ignored. Herein, to improve the interfacial adhesion of PCL based coating, a MgO/MgCO3 transition layer was prepared on the biodegradable WE43 magnesium alloy by a facile chemical conversion process in a deep eutectic solvent-based ionic liquid. Moreover, ZnO nanoparticles were loaded in the PCL to form a PCL/ZnO coating on the transition layer to further enhance corrosion resistance, biocompatibility, and antibacterial activity of the magnesium alloy substrate. Electrochemical corrosion test and in vitro biocompatibility tests, including cytotoxicity and antibacterial activity, were performed in a simulated body environment, which showed that the substrate covered by the double-layered coating possesses good corrosion resistance, biocompatibility and antibacterial ability.

Influence of ZnO doped into hydroxyapatite: Structural, electrical, biocompatibility, and antimicrobial assessment

The biocompatibility, antimicrobial activity, and dielectric properties of hydroxyapatite (HA) doped with different percentages of ZnO were studied. Hydroxyapatite was developed in samples heat-treated at 900°C/4 h; not affected by the addition of ZnO. The microstructure showed euhedral and subhedral hydroxyapatite crystals dispersed singly or accumulated in clusters. The biocompatibility test was implemented in simulated body fluid (SBF) for two weeks; a new HA layer on the soaked samples was developed. Antimicrobial and antifungal testing was conducted using agar diffusion; incorporating ZnO increased these effects. Dielectric measurements were performed at various frequencies; increasing ZnO content decreased the conductivity as the interfacial polarization increased and, hence, the concentration of Zn+2 cations triggered the decline in conductivity. With increasing zinc concentrations, antibacterial action expanded in the inhibition zones. Dielectric relaxation spectroscopy showed that the dielectric spectra were characterized at low and intermediate frequencies by a superposition of interfacial polarization and conductivity contribution. At high frequencies, all dynamics lagged behind the alteration of the external electric field, which made the permittivity values independent of neither the frequency of the applied field nor the composition of the investigated samples. The conductivity spectrum showed a considerable effect of the ZnO content in the HA matrix.

Autonomous Chemistry Enabling Environment-Adaptive Electrochemical Energy Storage Devices

Autonomous Chemistry Enabling Environment-Adaptive Electrochemical Energy Storage Devices

Biocompatibility Assessment of Two Commercial Bone Xenografts by In Vitro and In Vivo Methods.

Bone substitutes based on xenografts have been used for a long time in bone regeneration thanks to their inductive capacity for bone tissue regeneration. Some bone-based scaffolds have been modified by adding collagen and other proteins to improve their regenerative capacity and prevent migration and aggregation, especially particles. However, rejection of this graft has been reported due to protein residues caused by poor material preparation. We compared the in vitro and in vivo biological response of two commercial xenografts (InterOss®, F1 and InterOss® Collagen, F2) and a commercial porcine collagen membrane (InterCollagen® Guide, F3) as a rapid degradation control. Fourier Transform Infrared Spectroscopy (FT-IR) analysis evidenced the presence of hydroxyl, orthophosphate, and carbonate groups of the xenografts and amide groups of collagen. Thermogravimetric analysis (TGA) of the xenografts demonstrated their thermal stability and the presence of a few amounts of organic material. The study by differential scanning calorimetry showed the presence of endothermic peaks typical of the dehydration of the xenografts (F1 and F2) and for the collagen membrane (F3), the beginning of structural three-dimensional protein changes. Subsequently, in vitro biocompatibility tests were carried out for the materials with Artemia salina and MTT cell viability with HeLa cells, demonstrating the high biocompatibility of the materials. Finally, in vivo biocompatibility was studied by implanting xenografts in biomodels (Wistar rats) at different periods (30, 60, and 90 days). The F1 xenograft (InterOss) remained remarkably stable throughout the experiment (90 days). F2 (InterOss Collagen) presented a separation of its apatite and collagen components at 60 days and advanced resorption at 90 days of implantation. Finally, the collagen membrane (F3) presented faster resorption since, at 90 days, only some tiny fragments of the material were evident. All the in vivo and in vitro test results demonstrated the biocompatibility of the xenografts, demonstrating the potential of these materials for tissue engineering.

Low-intensity near-infrared light-tunable gold nanorod-incorporated hydrogel actuator system for remotely controlled human–robot interface applications

Light-responsive soft actuators have recently drawn attention as the need for lightweight remotely controlled actuator systems with high environmental adaptability and safe human–robot interaction interface characteristics has increased. In this study, we focused on a near-infrared (NIR) light-tunable hydrogel soft actuator system capable of fast and precisely controllable mechanical actuation even under the irradiation of NIR light with low intensity. We designed a bilayer type hydrogel soft actuator consisting of a poly(N-isopropylacrylamide) (PNIPAAm) active layer containing gold nanorods (AuNRs) as a photothermal agent and poly(acrylamide) (PAAm) passive layer. AuNRs with an aspect ratio of 4.12 showed the largest longitudinal plasmon resonance absorption peak in the NIR 880 nm range, which was used as a photothermal agent. The AuNR-incorporated PNIPAAm/PAAm hydrogel with a bilayer structure (PNIPAAm-AuNR/PAAm) exhibited more than 70% gel fraction and temperature-sensitive swelling behaviors. In particular, rod-shaped PNIPAAm-AuNR/PAAm hydrogels showed rapid bending deformation by a photothermally induced phase transition of PNIPAAm upon 880 nm laser irradiation, but a PNIPAAm/PAAm bilayer hydrogel without AuNRs did not show a light-induced bending movement. The NIR-responsive bending actuation of the hydrogel can be precisely controlled by cross-linking density, content of photothermal agent, NIR laser intensity, and thickness ratio of the active/passive layer. It was observed that the full bending deformations of the hydrogel into a ring shape through an arc occurred within a minute under NIR irradiation with a lower intensity of less than 1.0 W/cm2. Hydrogels showed a cell viability of more than 95% in the biocompatibility test, indicating no significant cytotoxicity. Therefore, these PNIPAAm-AuNR/PAAm hydrogels are promising soft actuator materials that can be controlled by low-intensity NIR irradiation for remotely controlled human–robot interaction interface applications.