Editorial on the Special Issue Entitled "Recent Advances in Aerogels"

Aerogels are unique solid materials that consist mainly of air and have an extremely low density, large open pores, and a large internal surface area [...].

Evaluation of ethanol-induced chitosan aerogels with human osteoblast cells

The following article provides an insight into the production of chitosan aerogels as potential materials for tissue engineering. Chitosan aerogels were prepared following two different protocols: formation in ethanol and formation in sodium hydroxide in an ethanol solution. The main objective was to apply a new route to obtain chitosan aerogels with no external cross-linkers and compare the mentioned preparation approaches. Forming chitosan aerogels in ethanol implies a simple, environmentally friendly, and efficient method. The prepared materials showed specific surface areas of up to 450 m2/g, highly porous networks and great mechanical properties. In vitro degradation studies revealed high stability for up to 10 weeks. The differences between the samples were significant. While the chitosan aerogels prepared in ethanol showed superior textural, morphological and mechanical properties, the chitosan aerogels prepared in the sodium hydroxide solution proved that a considerable influence on end properties could be made simply by adjusting the ageing medium. In vitro cell analysis with primary human osteoblasts showed good biocompatibility and pointed towards the potential use of these aerogels for orthopedic applications. This testing showed further that adjustments in structural properties by sodium hydroxide also come with a cost regarding their suitability to host bone cells.

Development of a novel NiCu nanoparticle-loaded polysaccharide-based hydrogel for 3D printing of customizable dressings with promising cytotoxicity against melanoma cells

Polysaccharide hydrogels and metal alloy nanoparticles have already found use in a range of biomedical applications. Nickel-copper nanoparticles (NiCu NPs) are particularly promising due to their tunable properties, such as ferromagnetism, biocompatibility, and antimicrobial activity. At the same time, polysaccharide hydrogels made of polymer mixtures such as alginate and methylcellulose with incorporated metal alloy nanoparticles are reported in the scientific literature. In view of this, in this work, NiCu NPs are combined with polysaccharide hydrogels and 3D printed to construct geometrically customizable dressings with tailorable properties for melanoma treatment. This novel combination exploits the intrinsic magnetic properties of NiCu NPs and the same time builds on their less known properties to improve the mechanic stability of 3D printed materials, both contributing to a previously not reported application as potent cytotoxic dressing against melanoma cells. The dressings were evaluated in terms of their physico-chemical characteristics, and their potential application, namely melanoma cell cytotoxicity. While all dressings exhibited similar degradation profiles regardless of composition, the addition of NiCu NPs had an effect on the hydrophilicity, swelling rates, and topographical properties of the dressings. Compression results showed that the presence of NPs increased the stiffness of the dressings, while the ultimate tensile strength was highest at 0.31 MPa for the dressings with 0.5 wt% NPs. We show that although the base formulation of the dressings is biocompatible with skin-derived cells, dressings loaded with NPs exhibit promising antimelanoma activity. Extracts obtained from dressings containing 0.5 wt% NPs reduced melanoma cell viability to 61% ± 11% and 40% ± 2% after 24 h and 72 h of soaking, respectively. Furthermore, extracts of dressings with 1 wt% NPs reduced melanoma cell viability to less than 15% within the first 24 h. By adjusting the NP content, the mechanical properties, surface roughness, and wettability can be tuned so that the dressings can be functionally customized. In addition, by using 3D printing as a fabrication process, the shape and composition of the dressings can be tailored to the patient's needs. The dressings also remained intact after soaking in simulated physiological solution for 14 days, indicating their suitability for long-term topical application.

Cell Electrospinning: A Mini-Review of the Critical Processing Parameters and Its Use in Biomedical Applications

Functional tissue engineering is a widely studied area of research with increasing importance in regenerative medicine, as well as in the development of in vitro models used for drug discovery and mimicking diseased tissues, among other applications. Electrospinning (ES) is one of the most widely used methods in these fields. It has attracted considerable interest because it can produce materials resembling the extracellular matrix of native tissues. The micro/nanofibers produced by this method provide a cell-friendly environment that promotes cellular activities. Cell electrospinning (C-ES) is based on the fundamental ES process and enables the encapsulation of viable cells in a micro/nanofibrous mesh. In this review, the process of C-ES and the materials used in this process are discussed. This work also discusses the applications of C-ES in tissue engineering, focusing on recent advances in this field.

Efficient and Green Isolation of Keratin from Poultry Feathers by Subcritical Water

The isolation of keratin from poultry feathers using subcritical water was studied in a batch reactor at temperatures (120-250 °C) and reaction times (5-75 min). The hydrolyzed product was characterized by FTIR and elemental analysis, while the molecular weight of the isolated product was determined by SDS-PAGE electrophoresis. To determine whether disulfide bond cleavage was followed by depolymerization of protein molecules to amino acids, the concentration of 27 amino acids in the hydrolysate was analyzed by GC/MS. The optimal operating parameters for obtaining a high molecular weight protein hydrolysate from poultry feathers were 180 °C and 60 min. The molecular weight of the protein hydrolysate obtained under optimal conditions ranged from 4.5 to 12 kDa, and the content of amino acids in the dried product was low (2.53% w/w). Elemental and FTIR analyses of unprocessed feathers and dried hydrolysate obtained under optimal conditions showed no significant differences in protein content and structure. Obtained hydrolysate is a colloidal solution with a tendency for particle agglomeration. Finally, a positive influence on skin fibroblast viability was observed for the hydrolysate obtained under optimal processing conditions for concentrations below 6.25 mg/mL, which makes the product interesting for various biomedical applications.

Review of Potential Drug-Eluting Contact Lens Technologies

The field of ophthalmology is expanding exponentially, both in terms of diagnostic and therapeutic capabilities, as well as the worldwide increasing incidence of eye-related diseases. Due to an ageing population and climate change, the number of ophthalmic patients will continue to increase, overwhelming healthcare systems and likely leading to under-treatment of chronic eye diseases. Since drops are the mainstay of therapy, clinicians have long emphasised the unmet need for ocular drug delivery. Alternative methods, i.e., with better compliance, stability and longevity of drug delivery, would be preferred. Several approaches and materials are being studied and used to overcome these drawbacks. We believe that drug-loaded contact lenses are among the most promising and are a real step toward dropless ocular therapy, potentially leading to a transformation in clinical ophthalmic practice. In this review, we outline the current role of contact lenses in ocular drug delivery, focusing on materials, drug binding and preparation, concluding with a look at future developments.

Single-Strain Probiotic Lactobacilli for the Treatment of Atopic Dermatitis in Children: A Systematic Review and Meta-Analysis

Probiotics are known for their positive effects on the gut microbiota. There is growing evidence that the infant gut and skin colonization have a role in the development of the immune system, which may be helpful in the prevention and treatment of atopic dermatitis. This systematic review focused on evaluating the effect of single-strain probiotic lactobacilli consumption on treating children's atopic dermatitis. Seventeen randomized placebo-controlled trials with the primary outcome of the Scoring Atopic Dermatitis (SCORAD) index were included in the systematic review. Clinical trials using single-strain lactobacilli were included. The search was conducted until October 2022 using PubMed, ScienceDirect, Web of Science, Cochrane library and manual searches. The Joanna Briggs Institute appraisal tool was used to assess the quality of the included studies. Meta-analyses and sub meta-analyses were performed using Cochrane Collaboration methodology. Due to different methods of reporting the SCORAD index, only 14 clinical trials with 1124 children were included in the meta-analysis (574 in the single-strain probiotic lactobacilli group and 550 in the placebo group) and showed that single-strain probiotic lactobacilli statistically significantly reduced the SCORAD index compared to the placebo in children with atopic dermatitis (mean difference [MD]: -4.50; 95% confidence interval [CI]: -7.50 to -1.49; Z = 2.93; p = 0.003; heterogeneity I² = 90%). The subgroup meta-analysis showed that strains of Limosilactobacillus fermentum were significantly more effective than strains of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei or Lacticaseibacillus rhamnosus. A longer treatment time and younger treatment age statistically significantly reduced symptoms of atopic dermatitis. The result of this systematic review and meta-analysis shows that certain single-strain probiotic lactobacilli are more successful than others in reducing atopic dermatitis severity in children. Therefore, careful consideration to strain selection, treatment time and the age of the treated patients are important factors in enhancing the effectiveness of reducing atopic dermatitis in children when choosing probiotic single-strain lactobacilli.

Multilayer Methacrylate-Based Wound Dressing as a Therapeutic Tool for Targeted Pain Relief

This study presents an innovative wound dressing system that offers a highly effective therapeutic solution for treating painful wounds. By incorporating the widely used non-steroidal anti-inflammatory drug diclofenac, we have created an active wound dressing that can provide targeted pain relief with ease. The drug was embedded within a biocompatible matrix composed of polyhydroxyethyl methacrylate and polyhydroxypropyl methacrylate. The multilayer structure of the dressing, which allows for sustained drug release and an exact application, was achieved through the layer-by-layer coating technique and the inclusion of superparamagnetic iron platinum nanoparticles. The multilayered dressings' physicochemical, structural, and morphological properties were characterised using various methods. The synergistic effect of the incorporated drug molecules and superparamagnetic nanoparticles on the surface roughness and release kinetics resulted in controlled drug release. In addition, the proposed multilayer wound dressings were found to be biocompatible with human skin fibroblasts. Our findings suggest that the developed wound dressing system can contribute to tailored therapeutic strategies for local pain relief.

Screen-printing of chitosan and cationised cellulose nanofibril coatings for integration into functional face masks with potential antiviral activity

Masks proved to be necessary protective measure during the COVID-19 pandemic, but they provided a physical barrier rather than inactivating viruses, increasing the risk of cross-infection. In this study, high-molecular weight chitosan and cationised cellulose nanofibrils were screen-printed individually or as a mixture onto the inner surface of the first polypropylene (PP) layer. First, biopolymers were evaluated by various physicochemical methods for their suitability for screen-printing and antiviral activity. Second, the effect of the coatings was evaluated by analysing the morphology, surface chemistry, charge of the modified PP layer, air permeability, water-vapour retention, add-on, contact angle, antiviral activity against the model virus phi6 and cytotoxicity. Finally, the functional PP layers were integrated into face masks, and resulting masks were tested for wettability, air permeability, and viral filtration efficiency (VFE). Air permeability was reduced for modified PP layers (43 % reduction for kat-CNF) and face masks (52 % reduction of kat-CNF layer). The antiviral potential of the modified PP layers against phi6 showed inhibition of 0.08 to 0.97 log (pH 7.5) and cytotoxicity assay showed cell viability above 70 %. VFE of the masks remained the same (~99.9 %), even after applying the biopolymers, confirming that these masks provided high level of protection against viruses.

The development of an electropolymerized, molecularly imprinted polymer (MIP) sensor for insulin determination using single-drop analysis

An electrochemical sensor for the detection of insulin in a single drop (50 μL) was developed based on the concept of molecularly imprinted polymers (MIP). The synthetic MIP receptors were assembled on a screen-printed carbon electrode (SPCE) by the electropolymerization of pyrrole (Py) in the presence of insulin (the protein template) using cyclic voltammetry. After electropolymerization, insulin was removed from the formed polypyrrole (Ppy) matrix to create imprinting cavities for the subsequent analysis of the insulin analyte in test samples. The surface characterization, before and after each electrosynthesis step of the MIP sensors, was performed using atomic force microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The performance of the developed MIP-SPCE sensor was evaluated using a single drop of solution containing K₃Fe(CN)₆ and the square-wave voltammetry technique. The MIP-SPCE showed a linear concentration range of 20.0-70.0 pM (R² = 0.9991), a limit of detection of 1.9 pM, and a limit of quantification of 6.2 pM. The rapid response time to the protein target and the portability of the developed sensor, which is considered a disposable MIP-based system, make this MIP-SPCE sensor a promising candidate for point-of-care applications. In addition, the MIP-SPCE sensor was successfully used to detect insulin in a pharmaceutical sample. The sensor was deemed to be accurate (the average recovery was 108.46%) and precise (the relative standard deviation was 7.23%).

Practical Use of Quartz Crystal Microbalance Monitoring in Cartilage Tissue Engineering

Quartz crystal microbalance (QCM) is a real-time, nanogram-accurate technique for analyzing various processes on biomaterial surfaces. QCM has proven to be an excellent tool in tissue engineering as it can monitor key parameters in developing cellular scaffolds. This review focuses on the use of QCM in the tissue engineering of cartilage. It begins with a brief discussion of biomaterials and the current state of the art in scaffold development for cartilage tissue engineering, followed by a summary of the potential uses of QCM in cartilage tissue engineering. This includes monitoring interactions with extracellular matrix components, adsorption of proteins onto biomaterials, and biomaterial–cell interactions. In the last part of the review, the material selection problem in tissue engineering is highlighted, emphasizing the importance of surface nanotopography, the role of nanofilms, and utilization of QCM as a “screening” tool to improve the material selection process. A step-by-step process for scaffold design is proposed, as well as the fabrication of thin nanofilms in a layer-by-layer manner using QCM. Finally, future trends of QCM application as a “screening” method for 3D printing of cellular scaffolds are envisioned.

Novel Methacrylate-Based Multilayer Nanofilms with Incorporated FePt-Based Nanoparticles and the Anticancer Drug 5-Fluorouracil for Skin Cancer Treatment

Despite medical advances, skin-associated disorders continue to pose a unique challenge to physicians worldwide. Skin cancer is one of the most common forms of cancer, with more than one million new cases reported each year. Currently, surgical excision is its primary treatment; however, this can be impractical or even contradictory in certain situations. An interesting potential alternative could lie in topical treatment solutions. The goal of our study was to develop novel multilayer nanofilms consisting of a combination of polyhydroxyethyl methacrylate (PHEMA), polyhydroxypropyl methacrylate (PHPMA), sodium deoxycholate (NaDOC) with incorporated superparamagnetic iron–platinum nanoparticles (FePt NPs), and the potent anticancer drug (5-fluorouracil), for theranostic skin cancer treatment. All multilayer systems were prepared by spin-coating and characterised by atomic force microscopy, infrared spectroscopy, and contact angle measurement. The magnetic properties of the incorporated FePt NPs were evaluated using magnetisation measurement, while their size was determined using transmission electron microscopy (TEM). Drug release performance was tested in vitro, and formulation safety was evaluated on human-skin-derived fibroblasts. Finally, the efficacy for skin cancer treatment was tested on our own basal-cell carcinoma cell line.

One-Step Fabrication of Hollow Spherical Cellulose Beads: Application in pH-Responsive Therapeutic Delivery

The path to greater sustainability and the development of polymeric drug delivery systems requires innovative approaches. The adaptation and use of biobased materials for applications such as targeted therapeutic delivery is, therefore, in high demand. A crucial part of this relates to the development of porous and hollow structures that are biocompatible, pH-responsive, deliver active substances, and contribute to pain relief, wound healing, tissue regeneration, and so forth. In this study, we developed a facile single-step and water-based method for the fabrication of hollow spherical cellulose beads for targeted drug release in response to external pH stimuli. Through base-catalyzed deprotection, hydrophobic solid and spherical cellulose acetate beads are transformed into hydrophilic cellulose structures with a hollow interior (wall thickness: 150 μm and inner diameter: 650 μm) by a stepwise increment of temperature and treatment time. Besides the pH-responsive fluid uptake properties, the hollow cellulose structures exhibit a maximum encapsulation efficiency of 20-85% diclofenac (DCF), a nonsteroidal anti-inflammatory drug, used commonly to treat pain and inflammatory diseases. The maximum amount of DCF released in vitro increased from 20 to 100% when the pH of the release medium increased from pH 1.2 to 7.4. As for the DCF release patterns and kinetic models at specific pH values, the release showed a diffusion- and swelling-controlled profile, effortlessly fine-tuned by external environmental pH stimuli. Overall, we show that the modified beads exhibit excellent characteristics for transport across the gastrointestinal tract and enhance the bioavailability of the drug. Their therapeutic efficacy and biocompatibility are also evident from the studies on human fibroblast cells. We anticipate that this platform could support and inspire the development of novel sustainable and effective polysaccharide-based delivery systems.

Artificial Biomimetic Electrochemical Assemblies

Rapid, selective, and cost-effective detection and determination of clinically relevant biomolecule analytes for a better understanding of biological and physiological functions are becoming increasingly prominent. In this regard, biosensors represent a powerful tool to meet these requirements. Recent decades have seen biosensors gaining popularity due to their ability to design sensor platforms that are selective to determine target analytes. Naturally generated receptor units have a high affinity for their targets, which provides the selectivity of a device. However, such receptors are subject to instability under harsh environmental conditions and have consequently low durability. By applying principles of supramolecular chemistry, molecularly imprinted polymers (MIPs) can successfully replace natural receptors to circumvent these shortcomings. This review summarizes the recent achievements and analytical applications of electrosynthesized MIPs, in particular, for the detection of protein-based biomarkers. The scope of this review also includes the background behind electrochemical readouts and the origin of the gate effect in MIP-based biosensors.

MFUM-BrTNBC-1, a Newly Established Patient-Derived Triple-Negative Breast Cancer Cell Line: Molecular Characterisation, Genetic Stability, and Comprehensive Comparison with Commercial Breast Cancer Cell Lines

Triple-negative breast cancer (TNBC) is a breast cancer (BC) subtype that accounts for approximately 15–20% of all BC cases. Cancer cell lines (CLs) provide an efficient way to model the disease. We have recently isolated a patient-derived triple-negative BC CL MFUM-BrTNBC-1 and performed a detailed morphological and molecular characterisation and a comprehensive comparison with three commercial BC CLs (MCF-7, MDA-MB-231, MDA-MB-453). Light and fluorescence microscopy were used for morphological studies; immunocytochemical staining for hormone receptor, p53 and Ki67 status; RNA sequencing, qRT-PCR and STR analysis for molecular characterisation; and biomedical image analysis for comparative phenotypical analysis. The patient tissue-derived MFUM-BrTNBC-1 maintained the primary triple-negative receptor status. STR analysis showed a stable and unique STR profile up to the 6th passage. MFUM-BrTNBC-1 expressed EMT transition markers and displayed changes in several cancer-related pathways (MAPK, Wnt and PI3K signalling; nucleotide excision repair; and SWI/SNF chromatin remodelling). Morphologically, MFUM-BrTNBC-1 differed from the commercial TNBC CL MDA-MB-231. The advantages of MFUM-BrTNBC-1 are its isolation from a primary tumour, rather than a metastatic site; good growth characteristics; phenotype identical to primary tissue; complete records of origin; a unique identifier; complete, unique STR profile; quantifiable morphological properties; and genetic stability up to (at least) the 6th passage.

Progressive use of multispectral imaging flow cytometry in various research areas

Multi-spectral imaging flow cytometry (MIFC) has become one of the most powerful technologies for investigating general analytics, molecular and cell biology, biotechnology, medicine, and related fields. It combines the capabilities of the morphometric and photometric analysis of single cells and micrometer-sized particles in flux with regard to thousands of events. It has become the tool of choice for a wide range of research and clinical applications. By combining the features of flow cytometry and fluorescence microscopy, it offers researchers the ability to couple the spatial resolution of multicolour images of cells and organelles with the simultaneous analysis of a large number of events in a single system. This provides the opportunity to visually confirm findings and collect novel data that would otherwise be more difficult to obtain. This has led many researchers to design innovative assays to gain new insight into important research questions. To date, it has been successfully used to study cell morphology, surface and nuclear protein co-localization, protein-protein interactions, cell signaling, cell cycle, cell death, and cytotoxicity, intracellular calcium, drug uptake, pathogen internalization, and other applications. Herein we describe some of the recent advances in the field of multiparametric imaging flow cytometry methods in various research areas.

Recent Advancements in 3D Printing of Polysaccharide Hydrogels in Cartilage Tissue Engineering

The application of hydrogels coupled with 3-dimensional (3D) printing technologies represents a modern concept in scaffold development in cartilage tissue engineering (CTE). Hydrogels based on natural biomaterials are extensively used for this purpose. This is mainly due to their excellent biocompatibility, inherent bioactivity, and special microstructure that supports tissue regeneration. The use of natural biomaterials, especially polysaccharides and proteins, represents an attractive strategy towards scaffold formation as they mimic the structure of extracellular matrix (ECM) and guide cell growth, proliferation, and phenotype preservation. Polysaccharide-based hydrogels, such as alginate, agarose, chitosan, cellulose, hyaluronan, and dextran, are distinctive scaffold materials with advantageous properties, low cytotoxicity, and tunable functionality. These superior properties can be further complemented with various proteins (e.g., collagen, gelatin, fibroin), forming novel base formulations termed "proteo-saccharides" to improve the scaffold's physiological signaling and mechanical strength. This review highlights the significance of 3D bioprinted scaffolds of natural-based hydrogels used in CTE. Further, the printability and bioink formation of the proteo-saccharides-based hydrogels have also been discussed, including the possible clinical translation of such materials.

Microvascular Tissue Engineering-A Review

Tissue engineering and regenerative medicine have come a long way in recent decades, but the lack of functioning vasculature is still a major obstacle preventing the development of thicker, physiologically relevant tissue constructs. A large part of this obstacle lies in the development of the vessels on a microscale-the microvasculature-that are crucial for oxygen and nutrient delivery. In this review, we present the state of the art in the field of microvascular tissue engineering and demonstrate the challenges for future research in various sections of the field. Finally, we illustrate the potential strategies for addressing some of those challenges.

Association between umbilical cord vitamin D levels and adverse neonatal outcomes

Objective

We investigated the associations between cord blood concentration of 25-hydroxyvitamin D [25(OH)D], neonatal outcomes, and the risk of hospitalization during the first year of life.

Methods

A total of 402 newborn infants and their mothers were prospectively enrolled and divided in four groups according to season of the year. We determined 25(OH)D serum concentrations from maternal–neonatal pairs at delivery by electrochemiluminescence immunoassay. Cut-offs at 25, 50, and 75 nmol/L defined vitamin D status, corresponding to deficiency, insufficiency, and sufficiency, respectively. Crude odds ratio (cOR) and 95% confidence intervals (CI) were estimated using logistic regression.

Results

Vitamin D severe deficiency (i.e., <25 nmol/L) was present in 18% of newborns. Cord blood severe deficiency was associated with an increased risk of preterm birth (cOR 3.6, 95% CI: 1.1–12.2), neonatal respiratory distress syndrome (cOR 5.9, 95% CI: 1.1–33.2), and increased risk of hospitalization during the first year of life because of acute respiratory infection (cOR 3.9, 95% CI: 1.4–10.6) or acute gastroenterocolitis (cOR 5.2, 95% CI: 1.4–19.1).

Conclusion

Cord blood vitamin D deficiency is associated with increased risk of preterm birth, neonatal respiratory distress syndrome, and hospitalization during the first year of life.

Design of In Vitro Hair Follicles for Different Applications in the Treatment of Alopecia-A Review

The hair research field has seen great improvement in recent decades, with in vitro hair follicle (HF) models being extensively developed. However, due to the cellular complexity and number of various molecular interactions that must be coordinated, a fully functional in vitro model of HFs remains elusive. The most common bioengineering approach to grow HFs in vitro is to manipulate their features on cellular and molecular levels, with dermal papilla cells being the main focus. In this study, we focus on providing a better understanding of HFs in general and how they behave in vitro. The first part of the review presents skin morphology with an emphasis on HFs and hair loss. The remainder of the paper evaluates cells, materials, and methods of in vitro growth of HFs. Lastly, in vitro models and assays for evaluating the effects of active compounds on alopecia and hair growth are presented, with the final emphasis on applications of in vitro HFs in hair transplantation. Since the growth of in vitro HFs is a complicated procedure, there is still a great number of unanswered questions aimed at understanding the long-term cycling of HFs without losing inductivity. Incorporating other regions of HFs that lead to the successful formation of different hair classes remains a difficult challenge.

Hybrid 3D Printing of Advanced Hydrogel-Based Wound Dressings with Tailorable Properties

Despite the extensive utilization of polysaccharide hydrogels in regenerative medicine, current fabrication methods fail to produce mechanically stable scaffolds using only hydrogels. The recently developed hybrid extrusion-based bioprinting process promises to resolve these current issues by facilitating the simultaneous printing of stiff thermoplastic polymers and softer hydrogels at different temperatures. Using layer-by-layer deposition, mechanically advantageous scaffolds can be produced by integrating the softer hydrogel matrix into a stiffer synthetic framework. This work demonstrates the fabrication of hybrid hydrogel-thermoplastic polymer scaffolds with tunable structural and chemical properties for applications in tissue engineering and regenerative medicine. Through an alternating deposition of polycaprolactone and alginate/carboxymethylcellulose gel strands, scaffolds with the desired architecture (e.g., filament thickness, pore size, macro-/microporosity), and rheological characteristics (e.g., swelling capacity, degradation rate, and wettability) were prepared. The hybrid fabrication approach allows the fine-tuning of wettability (approx. 50–75°), swelling (approx. 0–20× increased mass), degradability (approx. 2–30+ days), and mechanical strength (approx. 0.2–11 MPa) in the range between pure hydrogels and pure thermoplastic polymers, while providing a gradient of surface properties and good biocompatibility. The controlled degradability and permeability of the hydrogel component may also enable controlled drug delivery. Our work shows that the novel hybrid hydrogel-thermoplastic scaffolds with adjustable characteristics have immense potential for tissue engineering and can serve as templates for developing novel wound dressings.

Gynaecological cancers and their cell lines

Cell lines are widely used for various research purposes including cancer and drug research. Recently, there have been studies that pointed to discrepancies in the literature and usage of cell lines. That is why we have prepared a comprehensive overview of the most common gynaecological cancer cell lines, their literature, a list of currently available cell lines, and new findings compared with the original studies. A literature review was conducted via MEDLINE, PubMed and ScienceDirect for reviews in the last 5 years to identify research and other studies related to gynaecological cancer cell lines. We present an overview of the current literature with reference to the original studies and pointed to certain inconsistencies in the literature. The adherence to culturing rulesets and the international guidelines helps in minimizing replication failure between institutions. Evidence from the latest research suggests that despite certain drawbacks, variations of cancer cell lines can also be useful in regard to a more diverse genomic landscape.

Effects of the reservoir bag disconnection on inspired gases during general anesthesia: a simulator-based study

BACKGROUND

Fresh gas decoupling is a feature of the modern anesthesia workstation, where the fresh gas flow (FGF) is diverted into the reservoir bag and is not added to the delivered tidal volume, which thus remains constant. The present study aimed to investigate the entraining of the atmospheric air into the anesthesia breathing circuit in case the reservoir bag was disconnected.

METHODS

We conducted a simulator-based study, where the METI HPS simulator was connected to the anesthesia workstation. The effect of the disconnected reservoir bag was evaluated using oxygen (O2) and air or oxygen and nitrous oxide (N2O) as a carrier gas at different FGF rates. We disconnected the reservoir bag for 10 min during the maintenance phase. We recorded values for inspiratory O2, N2O, and sevoflurane. The time constant of the exponential process was estimated during reservoir bag disconnection.

RESULTS

The difference of O2, N2O and sevoflurane concentrations, before, during, and after reservoir bag disconnection was statistically significant at 0.5, 1, and 2 L/min of FGF (p < 0.001). The largest decrease of the inspired O2 concentrations (FIO2) was detected in the case of oxygen and air as the carrier gas and an FGF of 1 L/min, when oxygen decreased from median [25th-75th percentile] 55.00% [54.00-56.00] to median 39.50% [38.00-42.50] (p < 0.001). The time constant for FIO2 during reservoir bag disconnection in oxygen and air as the carrier gas, were median 2.5, 2.5, and 1.5 min in FGF of 0.5, 1.0, and 2 L/min respectively.

CONCLUSIONS

During the disconnection of the anesthesia reservoir bag, the process of pharmacokinetics takes place faster compared to the wash-in and wash-out pharmacokinetic properties in the circle breathing system. The time constant was affected by the FGF rate, as well as the gradient of anesthetic gases between the anesthesia circle system and atmospheric air.

Renal proximal tubular epithelial cells: review of isolation, characterization, and culturing techniques

The kidney is a complex organ, comprised primarily of glomerular, tubular, mesangial, and endothelial cells, and podocytes. The fact that renal cells are terminally differentiated at 34 weeks of gestation is the main obstacle in regeneration and treatment of acute kidney injury or chronic kidney disease. Furthermore, the number of chronic kidney disease patients is ever increasing and with it the medical community should aim to improve existing and develop new methods of renal replacement therapy. On the other hand, as polypharmacy is on the rise, thought should be given into developing new ways of testing drug safety. A possible way to tackle these issues is with isolation and culture of renal cells. Several protocols are currently described to isolate the desired cells, of which the most isolated are the proximal tubular epithelial cells. They play a major role in water homeostasis, acid-base control, reabsorption of compounds, and secretion of xenobiotics and endogenous metabolites. When exposed to ischemic, toxic, septic, or obstructive conditions their death results in what we clinically perceive as acute kidney injury. Additionally, due to renal cells' limited regenerative potential, the profibrotic environment inevitably leads to chronic kidney disease. In this review we will focus on human proximal tubular epithelial cells. We will cover human kidney culture models, cell sources, isolation, culture, immortalization, and characterization subdivided into morphological, phenotypical, and functional characterization.

Isolation, characterisation and phagocytic function of human macrophages from human peripheral blood

Macrophages are among the most important cells of the immune system. Among other functions, they take part in almost all defense actions against foreign bodies and bacteria, being particularly important in infections, wound healing, and foreign body reactions. Considering their importance for the health of the human body, as well as their important role in several diseases, the in vitro studies based on these cells, are a crucial research field. Taking all mentioned into account, this study describes a simple isolation method of human macrophages (MFUM-HMP-001 and MFUM-HMP-002 cell lines) from peripheral blood. For this purpose, the morphology, the viability, and the phagocytotic activity of the isolated cells were tested. The Immunostaining of MFUM-HMP-001 and MFUM-HMP-002 cells confirmed the macrophage cell markers CD68, CD80, and CD163/M130. The phagocytotic activity was marked in both MFUM-HMP-001 and MFUM-HMP-002 cells, as was the phagocytosis of the pHrodo green Escherichia coli bioparticles conjugates, which was enhanced with the addition of lipopolysaccharide. The cells were stable and exhibited good growth. According to our results, both cell lines are useful for the development of novel macrophage cell-based in vitro models.

In vitro toxicity model: Upgrades to bridge the gap between preclinical and clinical research

The Centers for Disease Control and Prevention (CDC) provides extensive data that indicate our need for drugs to maintain human population health. Despite the substantial availability of drugs on the market, many patients lack specific drugs. New drugs are required to tackle this issue. Moreover, we need more reliable models for testing drug toxicity, as too many drug approval failures occur with the current models. This article briefly describes various approaches of the currently used models for toxicity screening, to justify the selection of in vitro cell-based models. Cell-based toxicity models have the best potential to reliably predict drug toxicity in humans, as they are developed using the cells of the target organism. However, currently, a large gap exists between in vitro cell-based approach to toxicity testing and the clinical approach, which may be contributing to drug approval failures. We propose improvements to in vitro cell-based toxicity models, which is often an insight approach, to better match this approach with the clinical homeostatic approach. This should enable a more accurate comparison of data between the preclinical as well as clinical models and provide a more comprehensive understanding of human physiology and biological effects of drugs.

Polysaccharide-Based Bioink Formulation for 3D Bioprinting of an In Vitro Model of the Human Dermis

Limitations in wound management have prompted scientists to introduce bioprinting techniques for creating constructs that can address clinical problems. The bioprinting approach is renowned for its ability to spatially control the three-dimensional (3D) placement of cells, molecules, and biomaterials. These features provide new possibilities to enhance homology to native skin and improve functional outcomes. However, for the clinical value, the development of hydrogel bioink with refined printability and bioactive properties is needed. In this study, we combined the outstanding viscoelastic behavior of nanofibrillated cellulose (NFC) with the fast cross-linking ability of alginate (ALG), carboxymethyl cellulose (CMC), and encapsulated human-derived skin fibroblasts (hSF) to create a bioink for the 3D bioprinting of a dermis layer. The shear thinning behavior of hSF-laden bioink enables construction of 3D scaffolds with high cell density and homogeneous cell distribution. The obtained results demonstrated that hSF-laden bioink supports cellular activity of hSF (up to 29 days) while offering proper printability in a biologically relevant 3D environment, making it a promising tool for skin tissue engineering and drug testing applications.

Mechanical Properties and Cytotoxicity of Differently Structured Nanocellulose-hydroxyapatite Based Composites for Bone Regeneration Application

The nanocomposites were prepared by synthesizing (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized cellulose nanofibrils (TCNFs) or cellulose nanocrystals (CNCs) with hydroxyapatite (HA) in varying composition ratios in situ. These nanocomposites were first obtained from eggshell-derived calcium and phosphate of ammonium dihydrogen orthophosphate as precursors at a stoichiometric Ca/P ratio of 1.67 with ultrasonication and compressed further by a uniaxial high-pressure technique. Different spectroscopic, microscopic, and thermogravimetric analyses were used to evaluate their structural, crystalline, and morphological properties, while their mechanical properties were assessed by an indentation method. The contents of TCNF and CNC were shown to render the formation of the HA crystallites and thus influenced strongly on the composite nanostructure and further on the mechanical properties. In this sense, the TCNF-based composites with relatively higher contents (30 and 40 wt %) of semicrystalline and flexible TCNFs resulted in smoother and more uniformly distributed HA particles with good interconnectivity, a hardness range of 550-640 MPa, a compression strength range of 110-180 MPa, an elastic modulus of ~5 GPa, and a fracture toughness value of ~6 MPa1/2 in the range of that of cortical bone. Furthermore, all the composites did not induce cytotoxicity to human bone-derived osteoblast cells but rather improved their viability, making them promising for bone tissue regeneration in load-bearing applications.

Core/shell Printing Scaffolds For Tissue Engineering Of Tubular Structures

Three-dimensional (3D) printing of core/shell filaments allows direct fabrication of channel structures with a stable shell that is cross-linked at the interface with a liquid core. The latter is removed post-printing, leaving behind a hollow tube. Integrating an additive manufacturing technique (like the one described here with tailor-made [bio]inks, which structurally and biochemically mimic the native extracellular matrix [ECM]) is an important step towards advanced tissue engineering. However, precise fabrication of well-defined structures requires tailored fabrication strategies optimized for the material in use. Therefore, it is sensible to begin with a set-up that is customizable, simple-to-use, and compatible with a broad spectrum of materials and applications. This work presents an easy-to-manufacture core/shell nozzle with luer-compatibility to explore core/shell printing of woodpile structures, tested with a well-defined, alginate-based scaffold material formulation.

Nano- and Micropatterned Polycaprolactone Cellulose Composite Surfaces with Tunable Protein Adsorption, Fibrin Clot Formation, and Endothelial Cellular Response

This work describes the interaction of the human blood plasma proteins albumin, fibrinogen, and γ-globulins with micro- and nanopatterned polymer interfaces. Protein adsorption studies were correlated with the fibrin clotting time of human blood plasma and with the growth of primary human pulmonary artery endothelial cells (hECs) on these patterns. It was observed that blends of polycaprolactone (PCL) and trimethylsilyl-protected cellulose form various thin-film patterns during spin coating, depending on the mass ratio of the polymers in the spinning solutions. Vapor-phase acid-catalyzed deprotection preserves these patterns but yields interfaces that are composed of hydrophilic cellulose domains enclosed by hydrophobic PCL. The blood plasma proteins are repelled by the cellulose domains, allowing for a suggested selective protein deposition on the PCL domains. An inverse proportional correlation is observed between the amount of cellulose present in the films and the mass of irreversibly adsorbed proteins. This results in significantly increased fibrin clotting times and lower masses of deposited clots on cellulose-containing films as revealed by quartz crystal microbalance with dissipation measurements. Cell viability of hECs grown on these surfaces was directly correlated with higher protein adsorption and faster clot formation. The results show that presented patterned polymer composite surfaces allow for a controllable blood plasma protein coagulation and a significant biological response from hECs. It is proposed that this knowledge can be utilized in regenerative medicine, cell cultures, and artificial vascular grafts by a careful choice of polymers and patterns.

Polysaccharide Thin Solid Films for Analgesic Drug Delivery and Growth of Human Skin Cells

Chronic wounds not only lower the quality of patient's life significantly, but also present a huge financial burden for the healthcare systems around the world. Treatment of larger wounds often requires the use of more complex materials, which can ensure a successful renewal or replacement of damaged or destroyed tissues. Despite a range of advanced wound dressings that can facilitate wound healing, there are still no clinically used dressings for effective local pain management. Herein, alginate (ALG) and carboxymethyl cellulose (CMC), two of the most commonly used materials in the field of chronic wound care, and combination of ALG-CMC were used to create a model wound dressing system in the form of multi-layered thin solid films using the spin-assisted layer-by-layer (LBL) coating technique. The latter multi-layer system was used to incorporate and study the release kinetics of analgesic drugs such as diclofenac and lidocaine at physiological conditions. The wettability, morphology, physicochemical and surface properties of the coated films were evaluated using different surface sensitive analytical tools. The influence of in situ incorporated drug molecules on the surface properties (e.g., roughness) and on the proliferation of human skin cells (keratinocytes and skin fibroblasts) was further evaluated. The results obtained from this preliminary study should be considered as the basis for the development "real" wound dressing materials and for 3D bio-printing applications.

Functionalisation of Silicone by Drug-Embedded Chitosan Nanoparticles for Potential Applications in Otorhinolaryngology

Silicones are widely used medical materials that are also applied for tympanostomy tubes with a trending goal to functionalise the surface of the latter to enhance the healing of ear inflammations and other ear diseases, where such medical care is required. This study focuses on silicone surface treatment with various antimicrobial coatings. Polysaccharide coatings in the form of chitosan nanoparticles alone, or with an embedded drug mixture composed of amoxicillin/clavulanic acid (co-amoxiclav) were prepared and applied onto silicone material. Plasma activation was also used as a pre-treatment for activation of the material's surface for better adhesion of the coatings. The size of the nanoparticles was measured using the DLS method (Dynamic Light Scattering), stability of the dispersion was determined with zeta potential measurements, whilst the physicochemical properties of functionalised silicone materials were examined using the UV-Vis method (Ultraviolet-Visible Spectroscopy), SEM (Scanning Electron Microscopy), XPS (X-Ray Photoelectron Spectroscopy). Moreover, in vitro drug release testing was used to follow the desorption kinetics and antimicrobial properties were tested by a bacterial cell count reduction assay using the standard gram-positive bacteria Staphylococcus aureus. The results show silicone materials as suitable materials for tympanostomy tubes, with the coating developed in this study showing excellent antimicrobial and biofilm inhibition properties. This implies a potential for better healing of ear inflammation, making the newly developed approach for the preparation of functionalised tympanostomy tubes promising for further testing towards clinical applications.

Matrix Tablets for Controlled Release of Drugs Incorporated Using Capillary Absorption

Cost and time effectiveness make direct tableting still the favored method for tablet production. Among its most noticeable limitations in application is the non-uniformity (and/or inhomogeneities) in the contents of the resulting tablets, possibly leading to inconsistencies in required tablet properties. The efficiency of direct tableting is mostly affected by surface properties of the components to be tableted, which govern the final tablet mechanical and chemical properties and can influence the liquid capillary rise that the tablets exhibit after ingestion. By using capillary rise as a driving force, we developed a simple, yet powerful procedure for filling blank tablets with a repeatable drug amount. Blank tablets were prepared by direct compression of the excipient and filled with an organic solution of hydrochlorothiazide. Tablets were characterized regarding their structure and morphology, while their applicability was monitored using in vitro drug release studies. By utilizing the mentioned filling of blank tablets, we were able to incorporate the desired dose of the drug inside while maintaining the tablets initial mechanical properties. Moreover, most of the drug was incorporated in the tablet pores and the rest was homogeneously distributed over the tablet surface in the form of small particles, by which we also eliminated content non-uniformity (homogenous drug distribution through the tablet). To sum up, we not only developed a cheap, simple, and reproducible variation of direct tableting, but were also able to eliminate some of its biggest disadvantages (e.g., segregation of components, leading to inhomogeneities in contents, and incompatibility between different base ingredients due to their different surface properties). All mentioned make the proposed approach highly interesting for future use, especially in potential therapy individualization.

Systematic Evaluation of a Diclofenac-Loaded Carboxymethyl Cellulose-Based Wound Dressing and Its Release Performance with Changing pH and Temperature

Development of drug-loaded wound dressings is often performed without systematic consideration of the changing wound environment that can influence such materials' performance. Among the crucial changes are the wound pH and temperature, which have an immense effect on the drug release. Detailed release studies based on the consideration of these changing properties provide an important aspect of the in vitro performance testing of novel wound dressing materials. A sodium carboxymethyl cellulose-based wound dressing, with the incorporated non-steroidal anti-inflammatory drug diclofenac, was developed and characterised in regard to its physico-chemical, structural and morphological properties. Further, the influence of pH and temperature were studied on the drug release. Finally, the biocompatibility of the wound dressing towards human skin cells was tested. Incorporation of diclofenac did not alter important properties (water retention value, air permeability) of the host material. Changes in the pH and temperature were shown to influence the release performance and have to be accounted for in the evaluation of such dressings. Furthermore, the knowledge about the potential changes of these parameters in the wound bed could be used potentially to predict, and potentially even to control the drug release from the developed wound dressing. The prepared wound dressing was also proven biocompatible towards human skin cells, making it interesting for potential future use in the clinics.

A green approach to obtain stable and hydrophilic cellulose-based electrospun nanofibrous substrates for sustained release of therapeutic molecules

Stable and (bio)-compatible nanofibrous matrices showing effective incorporation and release of nonsteroidal anti-inflammatory drugs (NSAIDs) hold a huge potential in tissue regeneration and wound healing.

Novel electrospun fibers with incorporated commensal bacteria for potential preventive treatment of the diabetic foot

AIM

A novel electrospun biocompatible nanofibrous material loaded with commensal bacteria for potential preventive treatment of the diabetic foot was developed.

MATERIALS & METHODS

Two biocompatible polymers (carboxymethylcellulose and polyethylene oxide) were combined with a bacterium isolate from the skin located between the toes of a healthy adult (identified using a matrix-assisted laser desorption/ionization mass spectrometry-based method as a strain of Staphylococcus epidermidis). Higher bacteria loads in the material were assured through their encapsulation in polyethylenimine. The nanofibrous material was characterized using scanning electron microscopy, zeta-potential measurements and through evaluation of cell growth and viability.

RESULTS & DISCUSSION

nanometer formation was confirmed using scanning electron microscopy, while the zeta-potential measurements revealed successful bacteria encapsulation. Viable and sufficiently growing cells were confirmed prior and after their incorporation.

CONCLUSION

The prepared materials were proven suitable to deliver viable commensal bacteria in a comparable share to the Staphylococcaceae in the foot microbiome making this approach promising for preventive diabetic foot treatment.

Reusability of SPE and Sb-modified SPE Sensors for Trace Pb(II) Determination

In this work, unmodified screen-printed electrode (bare SPE) and Sb-film modified SPE (SbFSPE) sensors were employed for the analysis of trace amounts of Pb(II) in non-deaerated water solutions. The modified electrode was performed in situ in 0.5 mg/L Sb(III) and 0.01 M HCl. The methodology was validated for an accumulation potential of ⁻1.1 V vs. Ag/AgCl and an accumulation time of 60 s. A comparative analysis of bare SPE and SbFSPE showed that the detection and quantification limits decrease for the bare SPE. The method with the bare SPE showed a linear response in the 69.8⁻368.4 µg/L concentration range, whereas linearity for the SbFSPE was in the 24.0⁻319.1 µg/L concentration range. This work also reports the reason why the multiple standard addition method instead of a linear calibration curve for Pb(II) analysis should be employed. Furthermore, the analytical method employing SbFSPE was found to be more accurate and precise compared to the use of bare SPE when sensors were employed for the first time, however this performance changed significantly when these sensors were reused in the same manner. Furthermore, electrochemical impedance spectroscopy was used for the first time to analyse the electrochemical response of sensors after being used for multiple successive analyses. Surface characterisation before and after multiple successive uses of bare SPE and SbFSPE sensors, with atomic force microscopy and field emission scanning electron microscopy, showed sensor degradation. The interference effect of Cd(II), Zn(II), As(III), Fe(II), Na(I), K(I), Ca(II), Mg(II), NO₃⁻, Bi(III), Cu(II), Sn(II), and Hg(II) on the Pb(II) stripping signal was also studied. Finally, the application of SbFSPE was tested on a real water sample (from a local river), which showed high precision (RSD = 8.1%, n = 5) and accurate results.

A combination of interdisciplinary analytical tools for evaluation of multi-layered coatings on medical grade stainless steel for biomedical applications

In this comprehensive study several analytical techniques were used in order to evaluate multi-layered biomedical surface coatings composed of a drug (diclofenac) and a polymer (chitosan). Such a thorough examination is of paramount importance in order to assure safety and prove efficiency of potential biomedical materials already at the in vitro level, hence leading to their potentially faster introduction to clinical trials. For the first time a novel technique based on thermal diffusivity and conductivity measurements (photothermal beam deflection spectroscopy - BDS) was employed in order to analyse in a non-destructive way the thickness of respective layers, together with their thermal diffusivity and conductivity. In addition to attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), BDS confirmed successive surface layers of the prepared coatings. Scanning electron microscopy and atomic force microscopy were used to examine structural information on the macro- and micro/nano-scale, respectively. Surface hydrophobicity was measured with the contact angle analysis, which clearly showed differences in hydrophobicity between coated and non-coated samples. Considering the targeted application of the prepared coatings (as implant in orthopaedic treatments), the in vitro drug release was analysed spectrophotometrically to examine the coatings potential for a controlled drug release. Furthermore, the material was also tested by electrochemical impedance spectroscopy and cyclic polarisation techniques, which were able to detect even minor differences between the performance of the coated and non-coated materials. As the final test, the biocompatibility of the coatings with human osteoblasts was determined.

Multiple-Level Porous Polymer Monoliths with Interconnected Cellular Topology Prepared by Combining Hard Sphere and Emulsion Templating for Use in Bone Tissue Engineering

A combination of hard sphere and high internal phase emulsion templating gives a platform for synthesizing hierarchically porous polymers with a unique topology exhibiting interconnected spherical features on multiple levels. Polymeric spheres are fused by thermal sintering to create a 3D monolithic structure while an emulsion with a high proportion of internal phase and monomers in the continuous phase is added to the voids of the previously constructed monolith. Following polymerization of the emulsion and dissolution of the templating structure, a down-replicating topology is created with a primary level of pores as a result of fused spheres of the 3D monolithic structure, a secondary level of pores resulting from the emulsion's internal phase, and a tertiary level of interconnecting channels. Thiol-ene chemistry with divinyladipate and pentaerythritol tetrakis(3-mercaptopropionate) is used to demonstrate the preparation of a crosslinked polyester with overall porosity close to 90%. Due to multilevel porosity, such materials are interesting for applications in bone tissue engineering, possibly simulating the native sponge like bone structure. Their potential to promote ossteointegration is tested using human bone derived osteoblasts. Material-cell interactions are evaluated and they reveal growth and proliferation of osteoblasts both on surface and in the bulk of the scaffold.

Diagnosis and management of diaper dermatitis in infants with emphasis on skin microbiota in the diaper area

Diaper dermatitis is the most common inflammatory skin eruption within the diaper area in infants and toddlers. Although it rarely causes problems for prolonged periods of time, it causes considerable distress for both infants and parents. Diapered skin is exposed to friction, excessive hydration, varying pH, and is in constant contact with urine and feces, both of which are highly irritant to the skin. The three most common types of diaper dermatitis include chaffing dermatitis, irritant contact dermatitis, and diaper candidiasis. However, a variety of other skin conditions may manifest in the diaper area. Candida albicans and Staphylococcus aureus are most frequently isolated from the affected area and are thought to have a predominant role in diaper dermatitis. The review includes an overview of the epidemiology, etiology, and common skin microbiota in the diaper area. State-of-the-art strategies for diagnosis, management, and prevention of diaper dermatitis are also included. Appropriate skin care can help in the prevention of diaper dermatitis and can aid the reparation of the skin. This review discusses common causes, skin microbiota within the diapered area, differential diagnosis, and finally possible prevention and treatment recommendations. Recent findings have proven that the key to efficient eradication of irritant diaper dermatitis lies in its prevention.