Stability and biological response of PEGylated gold nanoparticles.

Stability and cytotoxicity of PEGylated Au NPs is crucial for biomedical application. In this study, we have focused on thermal stability of PEGylated Au NPs at 4 and 37 °C and after sterilization in autoclave. Gold nanoparticles were prepared by direct sputtering of gold into PEG and PEG-NH2. Transmission electron microscopy revealed that NPs exhibit a spherical shape with average dimensions 3.8 nm for both AuNP_PEG and AuNP_PEG-NH2. The single LSPR band at wavelength of 509 nm also confirmed presence of spherical Au NPs in both cases. Moreover, according to UV-Vis spectra, the Au NPs were overall stable during aging or thermal stressing and even after sterilization in autoclave. Based on gel electrophoresis results, the higher density of functionalizing ligands and the higher stability is assumed on AuNP_PEG-NH2. Changes in concentration of gold did not occur after thermal stress or with aging. pH values have to be adjusted to be suitable for bioapplications - original pH values are either too alkaline (AuNP_PEG-NH2, pH 10) or too acidic (AuNP_PEG, pH 5). Cytotoxicity was tested on human osteoblasts and fibroblasts. Overall, both Au NPs have shown good cytocompatibility either freshly prepared or even after Au NPs' sterilization in the autoclave. Prepared Au NP dispersions were also examined for their antiviral activity, however no significant effect was observed. We have synthesized highly stable, non-cytotoxic PEGylated Au NPs, which are ready for preclinical testing.

The Effect of Vascular Endothelial Growth Factor C and Adipose-Derived Stem Cells on Lymphatic Regeneration in a Rat Vascularized Lymph Node Transfer Model.

BACKGROUND: Lymphedema is a chronic condition characterized by progressive edema with complicated treatment. Recently, new treatment strategies inducing lymphangiogenesis were proposed. The aim of our study was to examine the effect of vascular endothelial growth factor C (VEGF-C) and adipose-derived stem cells (ADSCs) on lymphatic regeneration and drainage re-establishment in vascularized lymph node transfer (VLNT) model using a pedicled vascularized lymph node (VLN) groin flap. METHODS: Female Lewis rats with groin VLN flaps were utilized as a lymphedema model. Group A served as the control. Group B received VEGF-C. Group C received both VEGF-C and ADSCs. Group D received ADSCs only. Lymphatic drainage re-establishment was evaluated by ultrasound-photoacoustic imaging (US-PAI) after indocyanine green (ICG) injection. RESULTS: The fastest regeneration of elevated flaps was observed in Groups B and C in all monitored periods. After the first month, ICG positivity was detected in 14.3% of animals in Group A, 71.43% of animals in Group B (odds ratio [OR] = 15; p = 0.048), and 83.33% in Group C (OR = 30; p = 0.027). On the contrary, the difference between control group and Group D (16.67%; p = 0.905) was statistically insignificant. Administration of VEGF-C, ADSC + VEGF-C, and ADSC led to full flap regeneration after 6 months. The control group had the lowest percentage of ICG positivity at all monitored time points. CONCLUSION: We found that the fastest regeneration occurred with the combination of the VLN flap and VEGF-C. The addition of ADSC had an insignificant effect in our study. Furthermore, we proved the feasibility of PAI as an assessment tool of the lymphatic drainage recovery in a VLNT model.

Graphene 2D platform is safe and cytocompatibile for HaCaT cells growing under static and dynamic conditions.

The study concerns the influence of graphene monolayer, as a 2 D platform, on cell viability, cytoskeleton, adhesions sites andmorphology of mitochondria of keratinocytes (HaCaT) under static conditions. Based on quantitative and immunofluorescent analysis, it could be stated that graphene substrate does not cause any damage to membrane or disruption of other monitored parameters. Spindle poles and cytokinesis bridges indicating proliferation of cells on this graphene substrate were detected. Moreover, the keratinocyte migration rate on the graphene substrate was comparable to control glass substrate when the created wound was completely closed after 38 hours. HaCaT morphology and viability were also assessed under dynamic conditions (lab on a chip - micro scale). For this purpose, microfluidic graphene system was designed and constructed. No differences as well as no anomalies were observed during cultivation of these cells on the graphene or glass substrates in relation to cultivation conditions: static (macro scale) and dynamic (micro scale). Only natural percentage of dead cells was determined using different methods, which proved that the graphene as the 2 D platform is cytocompatible with keratinocytes. The obtained results encourage the use of the designed lab on a chip system in toxicity testing of graphene also on other cells and further research on the use of graphene monolayers to produce bio-bandages for skin wounds in animal tests.

VirPorters: Insights into the action of cationic and histidine-rich cell-penetrating peptides.

The utilization of nanoparticles for the intracellular delivery of theranostic agents faces one substantial limitation. Sequestration in intracellular vesicles prevents them from reaching the desired location in the cytoplasm or nucleus to deliver their cargo. We investigated whether three different cell-penetrating peptides (CPPs), namely, octa-arginine R8, polyhistidine KH27K and histidine-rich LAH4, could promote cytosolic and/or nuclear transfer of unique model nanoparticles-pseudovirions derived from murine polyomavirus. Two types of CPP-modified pseudovirions that carry the luciferase reporter gene were created: VirPorters-IN with CPPs genetically attached to the capsid interior and VirPorters-EX with CPPs noncovalently associated with the capsid exterior. We tested their transduction ability by luciferase assay and monitored their presence in subcellular fractions. Our results confirmed the overall effect of CPPs on the intracellular destination of the particles and suggested that KH27K has the potential to improve the cytosolic release of pseudovirions. None of the VirPorters caused endomembrane damage detectable by the Galectin-3 assay. Remarkably, a noncovalent modification was required to promote high transduction of the reporter gene and cytosolic delivery of pseudovirions mediated by LAH4. Together, CPPs in different arrangements have demonstrated their potential to improve pseudovirion invasion into cells, and these findings could be useful for the development of other nanoparticle-based delivery systems.

Laser Surface Modification of Powder Metallurgy-Processed Ti-Graphite Composite Which Can Enhance Cells' Osteo-Differentiation.

The paper examines the surface functionalization of a new type of Ti-graphite composite, a dental biomaterial prepared by vacuum low-temperature extrusion of hydrogenated-dehydrogenated titanium powder mixed with graphite flakes. Two experimental surfaces were prepared by laser micromachining applying different levels of incident energy of the fiber nanosecond laser working at 1064 nm wavelength. The surface integrity of the machined surfaces was evaluated, including surface roughness parameters measurement by contact profilometry and confocal laser scanning microscopy. The chemical and phase composition were comprehensively evaluated by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction analyses. Finally, the in vitro tests using human mesenchymal stem cells were conducted to compare the influence of the laser processing parameters used on the cell's cultivation and osteo-differentiation. The bioactivity results confirmed that the surface profile with positive kurtosis, platykurtic distribution curve and higher value of peaks spacing exhibited better bioactivity compared to the surface profile with negative kurtosis coefficient, leptokurtic distribution curve and lower peaks spacing.

Correction: Poly(acrylic acid)-mediated synthesis of cerium oxide nanoparticles with variable oxidation states and their effect on regulating the intracellular ROS level.

Correction for 'Poly(acrylic acid)-mediated synthesis of cerium oxide nanoparticles with variable oxidation states and their effect on regulating the intracellular ROS level' by Xiaohui Ju et al., J. Mater. Chem. B, 2021, 9, 7386-7400, DOI: 10.1039/D1TB00706H.

Poly(acrylic acid)-mediated synthesis of cerium oxide nanoparticles with variable oxidation states and their effect on regulating the intracellular ROS level.

Cerium oxide nanoparticles (CeNPs) possess multiple redox enzyme mimetic activities in scavenging reactive oxygen species (ROS) as a potential biomedicine. These enzymatic activities of CeNPs are closely related to their surface oxidation state. Here we have reported a synthetic method to modify CeNPs' surface oxidation state by changing the conformation of the poly(acrylic acid) (PAA) polymers adsorbed onto the CeNP surface. The synthesized PAA-CeNPs exhibited the same core size, morphology, crystal structure, and colloidal stability, with the only variation being their surface oxidation state (Ce3+ percentage). The modification mechanism can be attributed to the polymers chemisorbed onto the metal oxide surface forming a metal complexation structure. Such adsorption further modified CeNPs' surface oxidation state in a temperature-dependent manner. The series of PAA-CeNPs exhibited multiple redox enzyme mimetic activities (superoxide dismutase, catalase, peroxidase, and oxidase) directly related to their surface oxidation state. In vitro experiments showed no cytotoxic effect of these PAA-CeNPs on the osteoblastic cell line SAOS-2 at high loadings. Microscopic images confirmed the internalization of PAA-CeNPs in the cells. All tested PAA-CeNPs can reduce the basal and hydrogen peroxide-induced intracellular ROS level in the cells, indicating their effective intracellular ROS scavenging effect. However, we did not observe a positive correlation between the CeNP surface oxidation state and their capacities to reduce the intracellular ROS levels. We propose that CeNPs can maintain a dynamic state of Ce3+/Ce4+ during their catalytic activities, exhibiting a non-linear correlation between the CeNP surface oxidation state and their effect on regulating the intracellular ROS level.

The Impact of Various Culture Conditions on Human Mesenchymal Stromal Cells Metabolism.

In vitro and in vivo analyses are closely connected, and the reciprocal relationship between the two comprises a key assumption with concern to the conducting of meaningful research. The primary purpose of in vitro analysis is to provide a solid background for in vivo and clinical study purposes. The fields of cell therapy, tissue engineering, and regenerative medicine depend upon the high quality and appropriate degree of the expansion of mesenchymal stromal cells (MSCs) under low-risk and well-defined conditions. Hence, it is necessary to determine suitable alternatives to fetal bovine serum (FBS-the laboratory gold standard) that comply with all the relevant clinical requirements and that provide the appropriate quantity of high-quality cells while preserving the required properties. Human serum (autologous and allogeneic) and blood platelet lysates and releasates are currently considered to offer promising and relatively well-accessible MSC cultivation alternatives. Our study compared the effect of heat-inactivated FBS on MSC metabolism as compared to its native form (both are used as the standard in laboratory practice) and to potential alternatives with concern to clinical application-human serum (allogeneic and autologous) or platelet releasate (PR-SRGF). The influence of the origin of the serum (fetal versus adult) was also determined. The results revealed the key impact of the heat inactivation of FBS on MSCs and the effectiveness of human sera and platelet releasates with respect to MSC behaviour (metabolic activity, proliferation, morphology, and cytokine production).

Cytocompatibility of Graphene Monolayer and Its Impact on Focal Cell Adhesion, Mitochondrial Morphology and Activity in BALB/3T3 Fibroblasts.

This study investigates the effect of graphene scaffold on morphology, viability, cytoskeleton, focal contacts, mitochondrial network morphology and activity in BALB/3T3 fibroblasts and provides new data on biocompatibility of the "graphene-family nanomaterials". We used graphene monolayer applied onto glass cover slide by electrochemical delamination method and regular glass cover slide, as a reference. The morphology of fibroblasts growing on graphene was unaltered, and the cell viability was 95% compared to control cells on non-coated glass slide. There was no significant difference in the cell size (spreading) between both groups studied. Graphene platform significantly increased BALB/3T3 cell mitochondrial activity (WST-8 test) compared to glass substrate. To demonstrate the variability in focal contacts pattern, the effect of graphene on vinculin was examined, which revealed a significant increase in focal contact size comparing to control-glass slide. There was no disruption in mitochondrial network morphology, which was branched and well connected in relation to the control group. Evaluation of the JC-1 red/green fluorescence intensity ratio revealed similar levels of mitochondrial membrane potential in cells growing on graphene-coated and uncoated slides. These results indicate that graphene monolayer scaffold is cytocompatible with connective tissue cells examined and could be beneficial for tissue engineering therapy.

Immunomodulatory Potential of Differently-Terminated Ultra-Small Silicon Carbide Nanoparticles.

Ultra-small nanoparticles with sizes comparable to those of pores in the cellular membrane possess significant potential for application in the field of biomedicine. Silicon carbide ultra-small nanoparticles with varying surface termination were tested for the biological system represented by different human cells (using a human osteoblastic cell line as the reference system and a monocyte/macrophage cell line as immune cells). The three tested nanoparticle surface terminations resulted in the observation of different effects on cell metabolic activity. These effects were mostly noticeable in cases of monocytic cells, where each type of particle caused a completely different response ('as-prepared' particles, i.e., were highly cytotoxic, -OH terminated particles slightly increased the metabolic activity, while -NH2 terminated particles caused an almost doubled metabolic activity) after 24 h of incubation. Subsequently, the release of cytokines from such treated monocytes and their differentiation into activated cells was determined. The results revealed the potential modulation of immune cell behavior following stimulation with particular ultra-small nanoparticles, thus opening up new fields for novel silicon carbide nanoparticle biomedical applications.

Influence of cell-penetrating peptides on the activity and stability of virus-based nanoparticles.

Viral nanoparticles represent potential natural versatile platforms for targeted gene and drug delivery. Improving the efficiency of gene transfer mediated by viral vectors could not only enhance their therapeutic potential, but also contribute to understanding the limitations in interactions of nanoparticles with cells and the development of new therapeutic approaches. In this study, four cell-penetrating peptides (CPPs), cationic octaarginine (R8), histidine-rich peptides (LAH4 and KH27K) and fusogenic peptide (FUSO), are investigated for their effect on infection by mouse polyomavirus (MPyV) or on transduction of reporter genes delivered by MPyV or related viral vectors. Peptides noncovalently associated with viral particles enhance gene transfer (with the exception of FUSO). Removal of cellular heparan sulfates by the heparinase does not significantly change the enhancing potential of CPPs. Instead, CPPs influences the physical state of viral particles: R8 slightly destabilizes the intact virus, KH27K induces its aggregation and LAH4 promotes disassembly and aggregation of the particles that massively and rapidly associate with cells. The findings indicate that peptides acting as transduction-enhancing agents of polyomavirus-based nanoparticles modulate their physical state, which can be an important prerequisite for sensitization of cells and determination of the further fate of viral particles inside cells.

Colloidal stability and catalytic activity of cerium oxide nanoparticles in cell culture media.

One of the biggest challenges for the biomedical applications of cerium oxide nanoparticles (CeNPs) is to maintain their colloidal stability and catalytic activity as enzyme mimetics after nanoparticles enter the human cellular environment. This work examines the influences of CeNP surface properties on their colloidal stability and catalytic activity in cell culture media (CCM). Near-spherical CeNPs stabilized via different hydrophilic polymers were prepared through a wet-chemical precipitation method. CeNPs were stabilized via either electrostatic forces, steric forces, or a combination of both, generated by surface functionalization. CeNPs with electrostatic stabilization adsorb more proteins compared to CeNPs with only steric stabilization. The protein coverage further improves CeNPs colloidal stability in CCM. CeNPs with steric polymer stabilizations exhibited better resistance against agglomeration caused by the high ionic strength in CCM. These results suggest a strong correlation between CeNPs intrinsic surface properties and the extrinsic influences of the environment. The most stabilized sample in CCM is poly(acrylic acid) coated CeNPs (PAA-CeNPs), with a combination of both electrostatic and steric forces on the surface. It shows a hydrodynamic diameter of 15 nm while preserving 90% of its antioxidant activity in CCM. PAA-CeNPs are non-toxic to the osteoblastic cell line SAOS-2 and exhibit promising potential as a therapeutic alternative.

The Utilization of Cell-Penetrating Peptides in the Intracellular Delivery of Viral Nanoparticles.

Viral particles (VPs) have evolved so as to efficiently enter target cells and to deliver their genetic material. The current state of knowledge allows us to use VPs in the field of biomedicine as nanoparticles that are safe, easy to manipulate, inherently biocompatible, biodegradable, and capable of transporting various cargoes into specific cells. Despite the fact that these virus-based nanoparticles constitute the most common vectors used in clinical practice, the need remains for further improvement in this area. The aim of this review is to discuss the potential for enhancing the efficiency and versatility of VPs via their functionalization with cell-penetrating peptides (CPPs), short peptides that are able to translocate across cellular membranes and to transport various substances with them. The review provides and describes various examples of and means of exploitation of CPPs in order to enhance the delivery of VPs into permissive cells and/or to allow them to enter a broad range of cell types. Moreover, it is possible that CPPs are capable of changing the immunogenic properties of VPs, which could lead to an improvement in their clinical application. The review also discusses strategies aimed at the modification of VPs by CPPs so as to create a useful cargo delivery tool.

Positive impact of dynamic seeding of mesenchymal stem cells on bone-like biodegradable scaffolds with increased content of calcium phosphate nanoparticles.

One of the main aims of bone tissue engineering, regenerative medicine and cell therapy is development of an optimal artificial environment (scaffold) that can trigger a favorable response within the host tissue, it is well colonized by resident cells of organism and ideally, it can be in vitro pre-colonized by cells of interest to intensify the process of tissue regeneration. The aim of this study was to develop an effective tool for regenerative medicine, which combines the optimal bone-like scaffold and colonization technique suitable for cell application. Accordingly, this study includes material (physical, chemical and structural) and in vitro biological evaluation of scaffolds prior to in vivo study. Thus, porosity, permeability or elasticity of two types of bone-like scaffolds differing in the ratio of collagen type I and natural calcium phosphate nanoparticles (bCaP) were determined, then analyzes of scaffold interaction with mesenchymal stem cells (MSCs) were performed. Simultaneously, dynamic seeding using a perfusion bioreactor followed by static cultivation was compared with standard static cultivation for the whole period of cultivation. In summary, cell colonization ability was estimated by determination of cell distribution within the scaffold (number, depth and homogeneity), matrix metalloproteinase activity and gene expression analysis of signaling molecules and differentiation markers. Results showed, the used dynamic colonization technique together with the newly-developed collagen-based scaffold with high content of bCaP to be an effective combined tool for producing bone grafts for bone implantology and regenerative medicine.

Evaluation of collagen/hydroxyapatite electrospun layers loaded with vancomycin, gentamicin and their combination: Comparison of release kinetics, antimicrobial activity and cytocompatibility.

The aim of this study was to develop a biodegradable nanostructured electrospun layer based on collagen (COL), hydroxyapatite nanoparticles (HA), vancomycin hydrochloride (V), gentamicin sulphate (G) and their combination (VG) for the treatment of prosthetic joint infections and the prevention of infection during the joint replacement procedure. COL/HA layers containing different amounts of HA (0, 5 and 15 wt%) were tested for the in vitro release kinetics of antibiotics, antimicrobial activity against MRSA, gentamicin-resistant Staphylococcus epidermidis and Enterococcus faecalis isolates and cytocompatibility using SAOS-2 bone-like cells. The results revealed that the COL/HA layers released high concentrations of vancomycin and gentamicin for 21 days and performed effectively against the tested clinically-relevant bacterial isolates. The presence of HA in the collagen layers was found not to affect the release kinetics of the vancomycin from the layers loaded only with vancomycin or its combination with gentamicin. Conversely, the presence of HA slowed down the release of gentamicin from the COL/HA layers loaded with gentamicin and its combination with vancomycin. The combination of both antibiotics exerted a positive effect on the prolongation of the conversion of vancomycin into its degradation products. All the layers tested with different antibiotics exhibited potential antibacterial activity with respect to both the tested staphylococci isolates and enterococci. The complemental effect of vancomycin was determined against both gentamicin-resistant Staphylococcus epidermidis and Enterococcus faecalis in contrast to the application of gentamicin as a single agent. This combination was also found to be more effective against MRSA than is vancomycin as a single agent. Importantly, this combination of vancomycin and gentamicin in the COL/HA layers exhibited sufficient cytocompatibility to SAOS-2, which was independent of the HA content. Conversely, only gentamicin caused the death of SAOS-2 independently of HA content and only vancomycin stimulated SAOS-2 behaviour with an increased concentration of HA in the COL/HA layers. In conclusion, COL/HA layers with 15 wt% of HA impregnated with vancomycin or with a combination of vancomycin and gentamicin offer a promising treatment approach and the potential to prevent infection during the joint replacement procedures.

The effects of graphene and mesenchymal stem cells in cutaneous wound healing and their putative action mechanism.

This study provides a review of the therapeutic potential of graphene dressing scaffolds and mesenchymal stem cells (MSCs) and their synergistic effects with respect to cutaneous wound healing. This study also considers their putative action mechanism based on the antibacterial, immunomodulating, angiogenic, matrix remodeling effects of materials belonging to the graphene family and MSCs during the wound healing process. In addition, this study discusses the cytocompatibility of graphene, its uses as a platform for skin substitutes, the properties it possesses with respect to providing protection against microbial invasion as well as strategies aimed at minimizing the chance of the occurrence of sepsis. MSCs are capable of secreting several factors that exert a therapeutic impact on reparative processes and tissue regeneration. In light of experiments conducted to date, graphene combined with MSCs appears to have the potential to enhance both the wound healing process and infection control at the injury site.

Adipogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells in Pig Transgenic Model Expressing Human Mutant Huntingtin.

BACKGROUND: Although the highest expression of mutant huntingtin (mtHtt) was observed in the brain, its negative effects were also apparent in other tissues. Specifically, mtHtt impairs metabolic homeostasis and causes transcriptional dysregulation in adipose tissue. Adipogenic differentiation can be induced by the activation of two transcription factors: CCAAT/enhancer-binding protein alpha (CEBPα) and peroxisome proliferator-activated receptor gamma (PPARγ). These same transcription factors were found to be compromised in some tissues of Huntington's disease (HD) mouse models and in lymphocytes of HD patients. OBJECTIVE: This study investigated the adipogenic potential of mesenchymal stem cells (MSCs) derived from transgenic Huntington's disease (TgHD) minipigs expressing human mtHtt (1-548aa) containing 124 glutamines. Two differentiation conditions were used, employing PPARγ agonist rosiglitazone or indomethacin. METHODS: Bone marrow MSCs were isolated from TgHD and WT minipig siblings and compared by their cluster of differentiation using flow cytometry. Their adipogenic potential in vitro was analyzed using quantitative immunofluorescence and western blot analysis of transcription factors and adipogenic markers. RESULTS: Flow cytometry analysis did not reveal any significant difference between WT and TgHD MSCs. Nevertheless, following differentiation into adipocytes, the expression of CEBPα nuclear, PPARγ and adipogenic marker FABP4/AP2 were significantly lower in TgHD cells compared to WT cells. In addition, we proved both rosiglitazone and indomethacin to be efficient for adipogenic differentiation of porcine MSCs, with rosiglitazone showing a better adipogenic profile. CONCLUSIONS: We demonstrated a negative influence of mtHtt on adipogenic differentiation of porcine MSCs in vitro associated with compromised expression of adipogenic transcription factors.

Comparison of ground sections, paraffin sections and micro-CT imaging of bone from the epiphysis of the porcine femur for morphometric evaluation.

The aim of this study was to compare data on the volume fraction of bone and the thickness of the cortical compact bone acquired during microcomputed tomography (micro-CT) analysis with data acquired from identical samples using stereological analysis of either decalcified paraffin sections or ground sections. Additionally, we aimed to compare adjacent tissue samples taken from the major trochanter of the porcine femur to map the basic biological variability of trabecular bone. Fifteen pairs of adjacent tissue blocks were removed from the major trochanter of the proximal epiphyses of porcine femurs (female pigs aged 24-39 months, weight=59.16±8.15kg). In each sample, the volume of the cortical compact bone, the volume of the trabecular bone, and the thickness of the cortical compact bone was assessed using micro-CT. Afterwards, half of the samples were decalcified and processed using paraffin histological sections. Another half was processed into ground sections. The volume and thickness of bone was assessed in histological sections using stereological techniques. There were no significant differences in the bone volumes and thicknesses measured by micro-CT and the corresponding values quantified in decalcified sections. Similarly, there were no differences between the results from micro-CT and the analysis of the corresponding ground sections. Histomorphometric studies based on relatively low numbers of undecalcified ground sections or demineralized paraffin sections of bone yield data on bone volume and the thickness of cortical compact bone that is comparable with three-dimensional micro-CT examination. The pilot data on the variability of cortical compact bone and trabecular bone volumes in the porcine major trochanter provided in this study aim for planning experiments in the field of bone healing and implantology.

Surface modification of nanoporous anodic titanium dioxide layers for drug delivery systems and enhanced SAOS-2 cell response.

Nowadays, titanium and its alloys are the most commonly used implantable materials. The surface topography and chemistry of titanium-based implants are responsible for osseointegration. One of the methods to improve biocompatibility of Ti implants is a modification with sodium hydroxide (NaOH) or 3-aminopropyltriethoxysilane (APTES). In the present study, anodic titanium dioxide (ATO) layers were electrochemically fabricated, and then immersed in a NaOH solution or in NaOH and APTES solutions. The functionalized samples were characterized by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). All samples were examined as drug delivery systems and scaffolds for cell culturing. Based on the parameters of the fitted desorption-desorption-diffusion (DDD) model parameters, it was concluded that the modification with NaOH increased the amount of released ibuprofen and inhibited the release process. Osteoblast-like cell line (SAOS-2) was used to investigate the cell response on the non-modified and modified ATO samples. The MTS test and immunofluorescent staining were carried out to examine cell adhesion and proliferation. The data showed that the modification of nanoporous TiO2 layers with small molecules such as APTES enhanced metabolic activity of adhered cells compared with the non-modified and NaOH-modified TiO2 layers. In addition, the cells had a polygonal-like morphology with distinct projecting actin filaments and were well dispersed over the whole analyzed surface.

Generating standardized image data for testing and calibrating quantification of volumes, surfaces, lengths, and object counts in fibrous and porous materials using X-ray microtomography.

Quantification of the structure and composition of biomaterials using micro-CT requires image segmentation due to the low contrast and overlapping radioopacity of biological materials. The amount of bias introduced by segmentation procedures is generally unknown. We aim to develop software that generates three-dimensional models of fibrous and porous structures with known volumes, surfaces, lengths, and object counts in fibrous materials and to provide a software tool that calibrates quantitative micro-CT assessments. Virtual image stacks were generated using the newly developed software TeIGen, enabling the simulation of micro-CT scans of unconnected tubes, connected tubes, and porosities. A realistic noise generator was incorporated. Forty image stacks were evaluated using micro-CT, and the error between the true known and estimated data was quantified. Starting with geometric primitives, the error of the numerical estimation of surfaces and volumes was eliminated, thereby enabling the quantification of volumes and surfaces of colliding objects. Analysis of the sensitivity of the thresholding upon parameters of generated testing image sets revealed the effects of decreasing resolution and increasing noise on the accuracy of the micro-CT quantification. The size of the error increased with decreasing resolution when the voxel size exceeded 1/10 of the typical object size, which simulated the effect of the smallest details that could still be reliably quantified. Open-source software for calibrating quantitative micro-CT assessments by producing and saving virtually generated image data sets with known morphometric data was made freely available to researchers involved in morphometry of three-dimensional fibrillar and porous structures in micro-CT scans.