Editorial for the Special Issue: "Aerogel Hybrids and Nanocomposites".

Aerogel materials are porous ultralight solid materials obtained from gels, wherein a gas, commonly air, replaces the liquid component [...].

Aerogel-Based Materials in Bone and Cartilage Tissue Engineering-A Review with Future Implications.

Aerogels are fascinating solid materials known for their highly porous nanostructure and exceptional physical, chemical, and mechanical properties. They show great promise in various technological and biomedical applications, including tissue engineering, and bone and cartilage substitution. To evaluate the bioactivity of bone substitutes, researchers typically conduct in vitro tests using simulated body fluids and specific cell lines, while in vivo testing involves the study of materials in different animal species. In this context, our primary focus is to investigate the applications of different types of aerogels, considering their specific materials, microstructure, and porosity in the field of bone and cartilage tissue engineering. From clinically approved materials to experimental aerogels, we present a comprehensive list and summary of various aerogel building blocks and their biological activities. Additionally, we explore how the complexity of aerogel scaffolds influences their in vivo performance, ranging from simple single-component or hybrid aerogels to more intricate and organized structures. We also discuss commonly used formulation and drying methods in aerogel chemistry, including molding, freeze casting, supercritical foaming, freeze drying, subcritical, and supercritical drying techniques. These techniques play a crucial role in shaping aerogels for specific applications. Alongside the progress made, we acknowledge the challenges ahead and assess the near and far future of aerogel-based hard tissue engineering materials, as well as their potential connection with emerging healing techniques.

ß-Tricalcium Phosphate-Modified Aerogel Containing PVA/Chitosan Hybrid Nanospun Scaffolds for Bone Regeneration.

Electrospinning has recently been recognized as a potential method for use in biomedical applications such as nanofiber-based drug delivery or tissue engineering scaffolds. The present study aimed to demonstrate the electrospinning preparation and suitability of ß-tricalcium phosphate-modified aerogel containing polyvinyl alcohol/chitosan fibrous meshes (BTCP-AE-FMs) for bone regeneration under in vitro and in vivo conditions. The mesh physicochemical properties included a 147 ± 50 nm fibrous structure, in aqueous media the contact angles were 64.1 ± 1.7°, and it released Ca, P, and Si. The viability of dental pulp stem cells on the BTCP-AE-FM was proven by an alamarBlue assay and with a scanning electron microscope. Critical-size calvarial defects in rats were performed as in vivo experiments to investigate the influence of meshes on bone regeneration. PET imaging using 18F-sodium fluoride standardized uptake values (SUVs) detected 7.40 ± 1.03 using polyvinyl alcohol/chitosan fibrous meshes (FMs) while 10.72 ± 1.11 with BTCP-AE-FMs after 6 months. New bone formations were confirmed by histological analysis. Despite a slight change in the morphology of the mesh because of cross-linking, the BTCP-AE-FM basically retained its fibrous, porous structure and hydrophilic and biocompatible character. Our experiments proved that hybrid nanospun scaffold composite mesh could be a new experimental bone substitute bioactive material in future medical practice.

Environment-Friendly Catalytic Mineralization of Phenol and Chlorophenols with Cu- and Fe- Tetrakis(4-aminophenyl)-porphyrin-Silica Hybrid Aerogels.

Fenton reactions with metal complexes of substituted porphyrins and hydrogen peroxide are useful tools for the mineralization of environmentally dangerous substances. In the homogeneous phase, autooxidation of the prophyrin ring may also occur. Covalent binding of porphyrins to a solid support may increase the lifetime of the catalysts and might change its activity. In this study, highly water-insoluble copper and iron complexes of 5,10,15,20-tetrakis(4-aminophenyl)porphyrin were synthesized and bonded covalently to a very hydrophilic silica aerogel matrix prepared by co-gelation of the propyl triethoxysilyl-functionalized porphyrin complex precursors with tetramethoxysilane, followed by a supercritical carbon dioxide drying. In contrast to the insoluble nature of the porphyrin complexes, the as-prepared aerogel catalysts were highly compatible with the aqueous phase. Their catalytic activities were tested in the mineralization reaction of phenol, 3-chlorophenol, and 2,4-dichlorophenol with hydrogen peroxide. The results show that both aerogels catalyzed the oxidation of phenol and chlorophenols to harmless short-chained carboxylic acids under neutral conditions. In batch experiments, and also in a miniature continuous-flow tubular reactor, the aerogel catalysts gradually reduced their activity, due to the slow oxidation of the porphyrin ring. However, the rate and extent of the degradation was moderate and did not exclude the possibility that the as-prepared catalysts, as well as their more stable derivatives, might find practical applications in environment protection.

The Effect of Heat Treatment of ß-Tricalcium Phosphate-Containing Silica-Based Bioactive Aerogels on the Cellular Metabolism and Proliferation of MG63 Cells.

ß-Tricalcium phosphate was combined with silica aerogel in composites prepared using the sol-gel technique and supercritical drying. The materials were used in this study to check their biological activity and bone regeneration potential with MG63 cell experiments. The composites were sintered in 100 °C steps in the range of 500-1000 °C. Their mechanical properties, porosities, and solubility were determined as a function of sintering temperature. Dissolution studies revealed that the released Ca-/P molar ratios appeared to be in the optimal range to support bone tissue induction. Cell viability, ALP activity, and type I collagen gene expression results all suggested that the sintering of the compound at approximately 700-800 °C as a scaffold could be more powerful in vivo to facilitate bone formation within a bone defect, compared to that documented previously by our research team. We did not observe any detrimental effect on cell viability. Both the alkaline phosphatase enzyme activity and the type I collagen gene expression were significantly higher compared with the control and the other aerogels heat-treated at different temperatures. The mesoporous silica-based aerogel composites containing ß-tricalcium phosphate particles treated at temperatures lower than 1000 °C produced a positive effect on the osteoblastic activity of MG63 cells. An in vivo 6 month-long follow-up study of the mechanically strongest 1000 °C sample in rat calvaria experiments provided proof of a complete remodeling of the bone.

Care of patients with inborn errors of immunity in thirty J Project countries between 2004 and 2021.

Introduction: The J Project (JP) physician education and clinical research collaboration program was started in 2004 and includes by now 32 countries mostly in Eastern and Central Europe (ECE). Until the end of 2021, 344 inborn errors of immunity (IEI)-focused meetings were organized by the JP to raise awareness and facilitate the diagnosis and treatment of patients with IEI. Results: In this study, meeting profiles and major diagnostic and treatment parameters were studied. JP center leaders reported patients' data from 30 countries representing a total population of 506 567 565. Two countries reported patients from JP centers (Konya, Turkey and Cairo University, Egypt). Diagnostic criteria were based on the 2020 update of classification by the IUIS Expert Committee on IEI. The number of JP meetings increased from 6 per year in 2004 and 2005 to 44 and 63 in 2020 and 2021, respectively. The cumulative number of meetings per country varied from 1 to 59 in various countries reflecting partly but not entirely the population of the respective countries. Altogether, 24,879 patients were reported giving an average prevalence of 4.9. Most of the patients had predominantly antibody deficiency (46,32%) followed by patients with combined immunodeficiencies (14.3%). The percentages of patients with bone marrow failure and phenocopies of IEI were less than 1 each. The number of patients was remarkably higher that those reported to the ESID Registry in 13 countries. Immunoglobulin (IgG) substitution was provided to 7,572 patients (5,693 intravenously) and 1,480 patients received hematopoietic stem cell therapy (HSCT). Searching for basic diagnostic parameters revealed the availability of immunochemistry and flow cytometry in 27 and 28 countries, respectively, and targeted gene sequencing and new generation sequencing was available in 21 and 18 countries. The number of IEI centers and experts in the field were 260 and 690, respectively. We found high correlation between the number of IEI centers and patients treated with intravenous IgG (IVIG) (correlation coefficient, cc, 0,916) and with those who were treated with HSCT (cc, 0,905). Similar correlation was found when the number of experts was compared with those treated with HSCT. However, the number of patients treated with subcutaneous Ig (SCIG) only slightly correlated with the number of experts (cc, 0,489) and no correlation was found between the number of centers and patients on SCIG (cc, 0,174). Conclusions: 1) this is the first study describing major diagnostic and treatment parameters of IEI care in countries of the JP; 2) the data suggest that the JP had tremendous impact on the development of IEI care in ECE; 3) our data help to define major future targets of JP activity in various countries; 4) we suggest that the number of IEI centers and IEI experts closely correlate to the most important treatment parameters; 5) we propose that specialist education among medical professionals plays pivotal role in increasing levels of diagnostics and adequate care of this vulnerable and still highly neglected patient population; 6) this study also provides the basis for further analysis of more specific aspects of IEI care including genetic diagnostics, disease specific prevalence, newborn screening and professional collaboration in JP countries.

Rare-Earth Zirconate Ln2Zr2O7 (Ln: La, Nd, Gd, and Dy) Powders, Xerogels, and Aerogels: Preparation, Structure, and Properties.

The physicochemical properties of rare-earth zirconates can be tuned by the rational modification of their structures and phase compositions. In the present work, La3+-, Nd3+-, Gd3+-, and Dy3+-zirconate nanostructured materials were prepared by different synthetic protocols, leading to powders, xerogels, and, for the first time, monolithic aerogels. Powders were synthesized by the co-precipitation method, while xerogels and aerogels were synthesized by the sol-gel technique, followed by ambient and supercritical drying, respectively. Their microstructures, thermogravimetric profiles, textural properties, and crystallographic structures are reported. The co-precipitation method led to dense powders (SBET < 1 m2 g-1), while the sol-gel technique resulted in large surface area xerogels (SBET = 144 m2 g-1) and aerogels (SBET = 168 m2 g-1). In addition, the incorporation of lanthanide ions into the zirconia lattice altered the crystal structures of the powders, xerogels, and aerogels. Single-phase pyrochlores were obtained for La2Zr2O7 and Nd2Zr2O7 powders and xerogels, while defect fluorite structures formed in the case of Gd2Zr2O7 and Dy2Zr2O7. All aerogels contain a mixture of cubic and tetragonal ZrO2 phases. Thus, a direct effect is shown between the drying conditions and the resulting crystalline phases of the nanostructured rare-earth zirconates.

Controlled release of methotrexate from functionalized silica-gelatin aerogel microparticles applied against tumor cell growth.

Methotrexate functionalized silica-gelatin hybrid aerogel (SGM) was synthesized by the sol-gel method and co-gelation. The drug methotrexate (MTX) is covalently linked to the collagen molecules of the hybrid aerogel backbone by amide-bond. The characteristic MTX content of the functionalized hybrid aerogel is ca. 6 wt% by the dry weight. The micronization of SGM aerogel in water yields cell sized (d = 10-20 µm) particles. The cytotoxicity of these microparticles against tumor cell lines (SCC VII and HL-60) is unprecedentedly high, it is approximately equivalent to that of an equal dose of free (dissolved) MTX, as proved by in vitro experiments. Thus, the activity of MTX is intact after aerogel functionalization, and the mass specific cytotoxicity of SGM is high enough for medical applications. Drug release studies verified that MTX cannot be liberated from this drug delivery system solely by chemical hydrolysis, however, collagenase enzymatic activity releases MTX from the functionalized hybrid aerogel. The cytotoxicity of SGM towards various cancerous and non-cancerous cell lines correlates with the collagenase activities of cells. Therefore, conjugation with the hybrid aerogel provides a controlled release system for the antineoplastic agent MTX. The morphology of the delivery vehicle was chosen to adapt the size of cancer cells; thus the metastatic pathways of the tumor cells can get flooded.

[Spontaneous haemothorax - thoracic surgeon and intervention radiologist successful cooperation]. / Spontán haemothorax ­ mellkassebész és intervenciós radiológus sikeres együttmuködése.

The definition of spontaneous haemothorax is accumulation of blood within the pleural space without trauma or iatrogenic causes. A case of a 17-year-old male patient with a history of multiple abnormal arterial fistulas between systemic circulation and pulmonary circulation as a cause of bleeding is presented. An overview of the causes, the clinical features of haemothorax and the interventional radiological methods that can solve some causes of haemothorax are presented in connection of our case report.

[Carotid body tumor and its treatment. A case report]. / A glomus caroticum paragangliomája és ellátása.

Our goal was to report a 44-year-old woman with carotid body tumor, and to give a brief and comprehensive presentation about the disease and summarize its complex management. Carotid body tumor is a rare, mostly sporadic, benign head and neck mass originating from the glomus caroticum. It occurs mostly in middle-aged women as a slowly growing, semifix, painless neck mass. The diagnosis is based upon the physical examination (pulsatile mass, Fontaine-sign) and - as the gold standard - CT-angiography. It should be established that preoperative embolisation by digital substraction angiography plays a crucial role in the treatment of carotid body tumors that should be followed by surgical removal. In case of inoperable/irresecable and residual tumors, radiotherapy is the treatment option. The patient was treated in our department in April 2017. Orv Hetil. 2018; 159(36): 1487-1492.

Prevention of the Aggregation of Nanoparticles during the Synthesis of Nanogold-Containing Silica Aerogels.

Nanogold is widely used in many areas of physics and chemistry due to its environment-sensitive plasmon resonance absorption. The immobilization of gold nanoparticles in highly porous silica aerogel offers an attractive alternative to liquid gold solutions as they show a mechanically stable structure, are permeable to gases, and can even be used at elevated temperatures. We have found that the commercially available citrate-stabilized 10 nm gold nanoparticles may suffer from aggregation prior to or under the base-catalyzed gelation process of tetramethoxy silane. In the wet gels, Au particles increased in size, changed shape, and demonstrated the loss of plasmon resonance absorption, due to the formation of larger aggregates. We have studied a range of water-miscible organic solvents, stabilizing agents, and the gelation conditions to minimize changes from occurring in the aerogel setting and the supercritical drying process. It has been found that atmospheric carbon dioxide has a significant effect on aggregation, and it cannot be entirely excluded under normal synthetic conditions. Methanol resulted in an increase in the particle size only, while dimethyl sulfoxide, dimethylformamide, and urea changed the shape of nanoparticles to rod-like shapes, and diols led to an increase in both size and shape. However, using the polymeric stabilizer poly(vinyl pyrrolidone) efficiently prevented the aggregation of the particles, even in the presence of high concentrations of carbon dioxide, and allowed the production of nanoAu containing silica aerogels in a single step, without the modification of technology.

[The role of cone-beam CT during transarterial chemoembolization for liver cancer]. / A cone-beam CT szerepe a máj rosszindulatú daganatainak transarterialis chemoembolisatiós kezelésében.

PURPOSE: The role of interventional radiology in the treatment of hepatic malignancies is steeply raising. Our purpose is to present the importance of cone-beam CT (CBCT) during TACE (transarterial chemoembolization) procedures for liver tumours. PATIENTS AND METHODS: Between 1st of June 2013 and 31st of July 2016, we performed 130 TACE procedures in 64 patients in the Borsod University Teaching Hospital at Miskolc. During some of the treatments of 44 patients CBCT was also performed. RESULTS: All procedures were successful and carried out safely. CBCT gave new information in 22,7%, that influenced further treatment. It helped to precisely localize tumours, corrected the number or the size of hepatic malignancies. With CBCT it was easier to identify the feeding arteries of the tumour, plan the actual treatment and also to assess the efficacy of the previous treatment. DISCUSSION: The gold standard therapy of intermediate-stage HCC (according to Barcelona's criteria) is TACE. Beside, it can be safely and efficiently performed also in early stage or advanced stage in cases of contraindications for alternative therapies. Cone-beam CT is a dynamic examination which gives you an intraoperative, 3D CT-like imaging in the angio suit, without moving the table or the catheterised patient. Literature has already cited preliminary datas about prolonged survival for those patients treated with the help of CBCT intraoperatively. CONCLUSION: Intraoperative CBCT in patients with TACE treatment for hepatic malignancies can provide information that can improve the therapeutic results. Therefore we suggest the routine use of this imaging option during all TACE procedures if patients are eligible.

[Endovascular treatment of complex vascular pathology in neck and brain region. Case report]. / Komplex nyaki és agyi érpatológia endovascularis kezelése.

Authors present complex multistage endovascular treatment of female patient with an intradural infiltrative, inoperable tumor of the glomus jugulare, a stenosis of the internal carotid artery and an aneurysm of middle cerebri artery. In the literature our case report is the first announcement in which three pathology coexist ipsilateral in one patient and the patient has been treated step by step by endovascular procedures. Beside the endovascular treatment steps they display glomus jugulare tumor's symptoms, staging, treatment options and also the current treatment guidelines of internal carotid artery stenosis and intracranial aneurysms. Orv Hetil. 2017; 158(18): 706-710.

Management of carotid body tumor in pediatric patients: A case report and review of the literature.

Carotid body tumors (CBTs) are rare types of extra-adrenal paragangliomas, which originate from the neuroendocrine cells of the adventitial layer of carotid bifurcation. An 8-year-old girl was admitted to our department with left-sided and pulsating neck swelling, which progressively grew over several months. The patient had no family history of CBTs. Computed tomography (CT) and CT angiography (CTA) scans revealed a contrast material enhancing, hypervascularized mass involving the left carotid bifurcation, internal carotid artery (ICA), and external carotid artery (ECA), respectively. Preoperative embolization and surgical resection were performed. Histopathological examination later confirmed a benign CBT. Current follow-up examination revealed no evidence of residual or recurrent tumor. A systemic review of the literature indicates that early diagnosis, and experienced multi-disciplinary management is required in case of unilateral, resectable forms of CBTs with no distant metastasis, in order to provide a long-time survival of patients. Surgical intervention of unilateral, solitary CBTs with preoperative embolization is a relatively safe procedure, allowing complete tumor removal with minimal morbidity and low recurrence rate.

Mechanism of drug release from silica-gelatin aerogel-Relationship between matrix structure and release kinetics.

Specific features of a silica-gelatin aerogel (3 wt.% gelatin content) in relation to drug delivery has been studied. It was confirmed that the release of both ibuprofen (IBU) and ketoprofen (KET) is about tenfold faster from loaded silica-gelatin aerogel than from pure silica aerogel, although the two matrices are structurally very similar. The main goal of the study was to understand the mechanistic background of the striking difference between the delivery properties of these closely related porous materials. Hydrated and dispersed silica-gelatin aerogel has been characterized by NMR cryoporometry, diffusiometry and relaxometry. The pore structure of the silica aerogel remains intact when it disintegrates in water. In contrast, dispersed silica-gelatin aerogel develops a strong hydration sphere, which reshapes the pore walls and deforms the pore structure. The drug release kinetics was studied on a few minutes time scale with 1s time resolution. Simultaneous evaluation of all relevant kinetic and structural information confirmed that strong hydration of the silica-gelatin skeleton facilitates the rapid desorption and dissolution of the drugs from the loaded aerogel. Such a driving force is not operative in pure silica aerogels.

A Continuous Extraction and Pumpless Supercritical CO2 Drying System for Laboratory-Scale Aerogel Production.

Production of aerogels starts with solution chemistry and may end with supercritical carbon dioxide drying, which both require a specialized system. Here we present a complete aerogel production system that was developed and used in our laboratory over the last nine years. Our aim was to develop a supercritical dryer and a protocol, whereby the CO2 pump can be left out, and the entire flow system is operated by the pressure of the CO2 cylinder. Drying pressure and temperature are controlled by the combination of the filling and heating temperatures. A continuous-mode solvent exchange system has also been developed, in which the solvent consumption during the process can be reduced to one-third of the batch method. In the new medium temperature 1.5 L volume supercritical dryer, the temperature is set to a constant 80⁻82 °C, and the pressure can be in the 90⁻200 bar range, depending on the conditions. We have performed approximately 200 dryings thus far, and prepared a wide range of monolithic aerogels, from pristine silica aerogels to polysaccharides and collagen. In this paper, we have summarized not only the technical details, but also the work experiences, as well as advantages and disadvantages of the systems.

Hybrid aerogel preparations as drug delivery matrices for low water-solubility drugs.

A comprehensive study of 14 hybrid aerogels of different composition with applications in drug delivery has been carried out. The overall objective was to modulate the release behavior of drug-impregnated aerogels, from an almost instantaneous release to a semi-retarded delivery prolonged during several hours, through internal surface functionalization. The designed hybrid aerogels were composed of silica and gelatin and functionalized with either phenyl, long (16) hydrocarbon chain or methyl moiety. As model systems, three class II active agents (pKa<5.5), ibuprofen, ketoprofen and triflusal, were chosen to impregnate the aerogels. The work relied on the use of supercritical fluid technology for both the synthesis and functionalization of the hybrid aerogels, as well as for the impregnation with an active agent using supercritical CO2 as a solvent. For the impregnated aerogels, in vitro release profiles were recorded under gastric and intestinal pH-conditions using HPLC techniques. The release behavior observed for the three studied drugs was explained considering the measured dissolution profiles of the crystalline drugs, the aerogel composition and its functionalization. Such features are considered of great interest to tailor the bioavailability of drugs with low water solubility.

Segmentation of retinal vessels by means of directional response vector similarity and region growing.

This paper presents a novel retinal vessel segmentation method. Opposed to the general approach in similar directional methods, where only the maximal or summed responses of a pixel are used, here, the directional responses of a pixel are considered as a vector. The segmentation method is a unique region growing procedure which combines a hysteresis thresholding scheme with the response vector similarity of adjacent pixels. A vessel score map is constructed as the combination of the statistical measures of the response vectors and its local maxima to provide the seeds for the region growing procedure. A nearest neighbor classifier based on a rotation invariant response vector similarity measure is used to filter the seed points. Many techniques in the literature that capture the Gaussian-like cross-section of vessels suffer from the drawback of giving false high responses to the steep intensity transitions at the boundary of the optic disc and bright lesions. To overcome this issue, we also propose a symmetry constrained multiscale matched filtering technique. The proposed vessel segmentation method has been tested on three publicly available image sets, where its performance proved to be competitive with the state-of-the-art and comparable to the accuracy of a human observer, as well.

[Preparation and characteristics of aerogel-based bioactive materials used in dentistry]. / Fogászatban alkalmazható aerogél alapú bioaktív anyagok eloállítása és sajátosságai.

A variety of bioactive materials have been investigated as substitute materials for diseased or damaged bone tissues in dentistry. The aim of this study was to prepare mesoporous silica containing biomaterials by sol-gel technology. These materials may be combinated with hydroxyapatite and ß-tricalcium phosphate, as bioactive agents. The synthesis and testing of important physical parameters were performed. Based on these measurements, the silica aerogel can be an applicable material in the dental field in the future.