Tissue Equivalents Research Articles

Low-cost commercial graphite-rich pencils subjected to electron irradiation for passive radiation dosimetry

Various thicknesses of 2B grade polymer pencil lead graphite (PPLG) were used in the present study, which focussed on the alteration in crystalline lattice and the structural defect caused by the electron irradiation dosage ranging from 0.5 to 20 Gy delivered by an Elekta HD Linac. The fundamental trap parameters i.e. kinetics order (b), activation energy (E), and frequency factor (s) of the PPLG samples have been estimated using the initial rise and peak shape approaches by fitting the thermoluminescence (TL) glow peaks of the PPLG samples exposed to 20 Gy. The lifetime of the TL glow peak is also presented, which provides information on the stability of the TL signal at maximum temperatures. Raman, Photoluminescence (PL), and X-ray diffraction (XRD) spectra are being used to observe the structural changes that have occurred as a result of the radiation doses. These spectroscopies offer an understanding of the physical parameters that are related to the defects and taking part in the luminescence process. When all of the data are taken into account, it is anticipated that 0.3 mm PPLG is an effective material for dosimetry. The results of these lines of research are intended to educate the innovation of versatile graphite radiation dosimeters as a low-cost efficient system for radiation detection. The studied PPLG offers tissue equivalence as well as high spatial resolution, both are desirable criteria for a material to be used in the monitoring of ionising radiation or a variety of medical applications.

Modeling SARS-CoV-2 and influenza infections and antiviral treatments in human lung epithelial tissue equivalents

There is a critical need for physiologically relevant, robust, and ready-to-use in vitro cellular assay platforms to rapidly model the infectivity of emerging viruses and develop new antiviral treatments. Here we describe the cellular complexity of human alveolar and tracheobronchial air liquid interface (ALI) tissue models during SARS-CoV-2 and influenza A virus (IAV) infections. Our results showed that both SARS-CoV-2 and IAV effectively infect these ALI tissues, with SARS-CoV-2 exhibiting a slower replication peaking at later time-points compared to IAV. We detected tissue-specific chemokine and cytokine storms in response to viral infection, including well-defined biomarkers in severe SARS-CoV-2 and IAV infections such as CXCL10, IL-6, and IL-10. Our single-cell RNA sequencing analysis showed similar findings to that found in vivo for SARS-CoV-2 infection, including dampened IFN response, increased chemokine induction, and inhibition of MHC Class I presentation not observed for IAV infected tissues. Finally, we demonstrate the pharmacological validity of these ALI tissue models as antiviral drug screening assay platforms, with the potential to be easily adapted to include other cell types and increase the throughput to test relevant pathogens.

The possibilities of using bioengineered skin substitutes in combustiology (literature review)

Relevance. Despite scientific and technological progress and improvement of treatment methods, providing assistance for thermal burns of the skin remains a complex multicomponent problem. Extensive deep burns are not capable of self-healing, and therefore, over the past century, autodermoplasty has become the standard method of treatment. However, the shortage of healthy tissues of the patient often does not allow the transplantation to be performed in full, which entails the need to search for options for replacing auto-tissues.Intention. To present modern possibilities and evaluate the problems of using bioengineered skin substitutes in kombustiology.Methodology. Scientific literary sources published in recent years were searched for using the PubMed database and the platform of Scientific Electronic Library (eLIBRARY.ru ).Results and Discussion. Currently, many skin substitutes have been developed, ranging from single-layer tissue equivalents to artificial leather and genetically modified substitutes. However, all of them are still far from perfect, they have their advantages and disadvantages, which determine the features of their application and necessitate further research.Conclusion. The development of tissue equivalents of the skin has significantly improved the results of treatment of victims with deep burns and is a promising direction in the development of modern combustiology.

Impact of Salt on Thermal Stability and Dose Response of the Fricke-XO-Pluronic F-127 3D Radiotherapy Dosimeter.

Fricke-XO-Pluronic F-127 has recently been proposed as a 3D dosimeter for radiotherapy. It contains the typical ingredients of the Fricke ionizing radiation dosimeter, which are embedded in a physical gel of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127). The main reactions upon irradiation are the conversion of Fe+2 to Fe+3 and the formation of a colored complex with XO ([XO-Fe]+3). The study attempts to optimize the dosimeter in terms of its solution-to-gel transition temperature. In order to lower this temperature, the use of NaCl salt has been proposed. The new composition was characterized in order to obtain information on its thermal performance, storage stability, dose response to irradiation with a medical accelerator emitting different types of radiation, and tissue equivalence. The results obtained show an improvement in the sol-gel transition temperature and dose sensitivity compared to the composition without NaCl and broaden the knowledge of the Fricke-XO-Pluronic F-127.

Design of an Integrated Microvascularized Human Skin-on-a-Chip Tissue Equivalent Model.

Tissue-engineered skin constructs have been under development since the 1980s as a replacement for human skin tissues and animal models for therapeutics and cosmetic testing. These have evolved from simple single-cell assays to increasingly complex models with integrated dermal equivalents and multiple cell types including a dermis, epidermis, and vasculature. The development of micro-engineered platforms and biomaterials has enabled scientists to better recreate and capture the tissue microenvironment in vitro, including the vascularization of tissue models and their integration into microfluidic chips. However, to date, microvascularized human skin equivalents in a microfluidic context have not been reported. Here, we present the design of a novel skin-on-a-chip model integrating human-derived primary and immortalized cells in a full-thickness skin equivalent. The model is housed in a microfluidic device, in which a microvasculature was previously established. We characterize the impact of our chip design on the quality of the microvascular networks formed and evidence that this enables the formation of more homogenous networks. We developed a methodology to harvest tissues from embedded chips, after 14 days of culture, and characterize the impact of culture conditions and vascularization (including with pericyte co-cultures) on the stratification of the epidermis in the resulting skin equivalents. Our results indicate that vascularization enhances stratification and differentiation (thickness, architecture, and expression of terminal differentiation markers such as involucrin and transglutaminase 1), allowing the formation of more mature skin equivalents in microfluidic chips. The skin-on-a-chip tissue equivalents developed, because of their realistic microvasculature, may find applications for testing efficacy and safety of therapeutics delivered systemically, in a human context.

Accelerating and improving radiochromic film calibration by utilizing the dose ratio in photon and proton beams.

PurposeRadiochromic films are versatile 2D dosimeters with high‐resolution and near tissue equivalence. To assure high precision and accuracy, a time‐consuming calibration process is required. To improve the time efficiency, a novel calibration method utilizing the ratio of the same dose profile measured at different monitor units (MUs) is introduced and tested in a proton and photon beam.MethodsThe calibration procedure employs the dose ratio of film measurements of the same relative profile for different absolute dose values. Hence, the ratio of the dose is constant at any point of the profile, but the ratio of the net optical densities is not constant. The key idea of the method is to optimize the calibration function until the ratio of the calculated doses is constant. The proposed method was tested in the dose range between 0.25–12 and 1–6 Gy in a proton and photon beam, respectively. A radial symmetric profile and a rectangular profile were created, both having a central plateau region of about 3 cm diameter and a dose falloff of about 1.5 cm at larger distances. The dose falloff region was used as input for the optimization method and the central plateau region served as dose reference points. Only the plateau region of the highest dose entered the optimization as an additional objective. The measured data were randomly split into differently sized training and test sets. The optimization was repeated 1000 times with random start value initialization using the same start values for the standard and the gradient method. Finally, a proton plan with four dose levels was created, which were separated spatially, to test the possibility of a full calibration within a single measurement.ResultsParameter estimation was possible with as low as one dose ratio used for optimization in both the photon and the proton case, yet exhibiting a high sensitivity on the dose level. The root mean squared deviation (RMSD) of the dose was less than 1% when the dose ratio was in the order of 20, whereas the median RMSD of all optimizations was 1.7%. Using four dose levels for optimization resulted in a median RMSD of 1% when randomly selecting the dose levels. Having at least one dose ratio of about 20 included in the optimization considerably improved the RMSD of the calibration function. Using six or eight dose levels reduced the sensitivity on the dose level selection and the median RMSD was 0.8%. A full calibration was possible in a single measurement having four dose levels in one plan but spatially separated.ConclusionsThe number of measurements required to obtain an EBT3 film calibration function could be reduced using the proposed dose ratio method while maintaining the same accuracy as with the standard method.

Macromolecular crowding transforms regenerative medicine by enabling the accelerated development of functional and truly three-dimensional cell assembled micro tissues

Scaffold-free in vitro organogenesis exploits the innate ability of cells to synthesise and deposit their own extracellular matrix to fabricate tissue-like assemblies. Unfortunately, cell-assembled tissue engineered concepts require prolonged ex vivo culture periods of very high cell numbers for the development of a borderline three-dimensional implantable device, which are associated with phenotypic drift and high manufacturing costs, thus, hindering their clinical translation and commercialisation. Herein, we report the accelerated (10 days) development of a truly three-dimensional (338.1 ± 42.9 μm) scaffold-free tissue equivalent that promotes fast wound healing and induces formation of neotissue composed of mature collagen fibres, using human adipose derived stem cells seeded at only 50,000 cells/cm2 on an poly (N-isopropylacrylamide-co-N-tert-butylacrylamide (PNIPAM86-NTBA14) temperature-responsive electrospun scaffold and grown under macromolecular crowding conditions (50 μg/ml carrageenan). Our data pave the path for a new era in scaffold-free regenerative medicine.

Development of an anthropomorphic phantom based on 3D printing for assessment of dose delivered to the eye and adjacent tissues

The objective of this work was to build slices containing the eye region using 3D printing, to be inserted in an anthropomorphic phantom, allowing to perform the dosimetry of organs associated with the eye. The slices were built using PLA 3D printing for soft tissue and a mixture of calcium sulfate dihydrate and sodium chloride for the cranial bones. Different mixtures were tested to simulate bone tissue. The phantom containing LiF TLD 100 micro cubes in proper positions was validated for the determination of doses to the eye and to organs at risk. For the mass attenuation coefficient and energies between 1 and 10 MeV, the percentage differences between the data for the three mixtures and that for cortical bone was less than 2%. When analyzing the electronic density, all mixtures differed by more than 10% in relation to bone tissue. The use of Hounsfield Units as the only parameter to characterize the tissue equivalence is not recommended. The results showed that the mixture with 46% calcium sulfate is the closest to the cortical bone of the ATOM® phantom. The printed phantom containing TLDs was used to measure the doses in deeper regions of ocular system as the optical nerves and fundus of the eye. The results differed about 2% from the planned ones. For more superficial regions (like the lens), the use of dose compensators should be used to provide electronic equilibrium conditions. Results showed the feasibility of using the three-dimensional printed phantom developed.

The efficacy of various thicknesses of float glasses for protection of gamma-radiation

Recognizing the availability and low cost of marketable glasses, this study evaluates the radiation protection efficacy of various thicknesses of float glasses used in Bangladeshi dwellings. Numerous float glasses differing in widths (2.5 mm, 3.2 mm, 5.0 mm, 5.9 mm, 7.9 mm, and 10 mm) and produced by the Nasir glass industry in Bangladesh are studied herein. In this regard, at energies 59 keV, 661 keV, 1173 keV, and 1332 keV, the major radiation protection attributes such as effective atomic number, narrow-beam absorption coefficients, mass absorption coefficients, half-value layer, and radiation protection efficiency have been evaluated. The incident and transmitted photon intensity have been measured via a well-shielded HPGe gamma-ray detector accompanied by obligatory electronics. The values of narrow-beam absorption coefficients of the studied glass specimens show a decreasing trend of SNG-1>SNG-2>SNG-3>SNG-4>SNG-5>SNG-6. It has been perceived that the effective atomic number of the glass specimen is 13.6, which shows good aspirants of TLD-200 (Zeff = 16.3) as well as bone tissue equivalence. Based on the half-value layer (HVL) study, the lowest and highest thickness glass specimens SNG-1 (2.5 mm) and SNG-6 (10 mm) have lessened the incident radiation by 7% and 20%, respectively. On the other hand, the specimen SNG-6 has offered almost 2.5 times higher radiation protection efficacy than the specimen SNG-1 studied herein.

Evaluation of brass alloy density as tissue equivalence bolus using electron density phantom and optical density method

The brass mesh bolus alloy has been shown to be a promising substitute for tissue-equivalent bolus to increase the surface dose during breast cancer radiotherapy treatment. This study is aimed to evaluate the brass alloy density in order to better understand the brass qualities as a bolus in radiotherapy. The mass density of brass alloy determined in this work are using solid approaches, i) traditional density method, ii) Computed Tomography (CT) number using electron density phantom and CT scan and iii) mean pixel value via ImageJ software. According to ANOVA F (2,6) 2.982, p0.126, there was no statistically significant difference between the groups. As a result, all methods for calculating the density of brass alloy are valid. The X2 test of CT number of brass plug to breast substitute in electron density phantom indicates no association. Density analysis using computed tomography and an electron density phantom, as well as the traditional density method and Image J analysis, were all shown to be acceptable methods for estimating the density of the brass alloy. Considering this, brass alloy can be considered as a potential substitute for tissue-equivalent bolus with further extensive of research in conjunction to CT number.

Facile functionalization of YVO4:Eu3+: From nanoparticles to luminescent PMMA nanocomposites for radiation detectors

YVO4:Eu3+ is a luminescent material that has been widely used in cathode ray tubes and plasma display panels. Nowadays, different applications are being explored. Fiber-optic Dosimetry (FOD) is an alternative to traditional dosimetry systems for radiotherapy treatments. Although some published results have demonstrated the potential of using YVO4:Eu3+ as nanometer powder for FOD systems, none of them tend to improve its tissue equivalence, a significant limitation. One possible solution could be to disperse the NPs in a tissue-equivalent polymer matrix, like Poly Methyl Methacrylate (PMMA). Consequently, YVO4:Eu3+/PMMA nanocomposites were developed using NPs synthesized according to a combustion method previously reported. This work focuses on studying two different NPs functionalization strategies. One of them involves the synthesis of a SiO2 shell and a posterior treatment with Oleic Acid (OA). The other involves the use of a silane (3-(Trimethoxysilyl)propyl methacrylate, TMSPM) as a coupling agent. Both strategies allow the surface modification of NPs. The study of luminescence properties of NPs showed no significant changes between both functionalized NPs related to Eu3+ spectrum characteristic peaks. However, YVO4:Eu3+@TMSPM has better performance (the reduction in YVO4:Eu3+@TMSPM is about 15%, while in YVO4:Eu3+@SiO2@OA is 62%). On the other hand, functionalized nanoparticles were used to develop polymeric nanocomposites (PNCs) by in situ polymerization of Methyl Methacrylate using a cyclic triperoxide as initiator. Functionalized NPs were characterized by Fourier Transform Infrared Spectroscopy, Transmission Electron Microscopy, Dynamic Light Scattering, Thermogravimetric Analysis, and luminescence measurements. Films were obtained by dissolution of the PNCs, and their luminescent properties were also studied. Results indicate that although the strategy that involves the silica shell plus OA is better in terms of cover density, the TMSPM promotes a better dispersion on the polymer matrix.

Effect of scanner lens on lateral response artefact in radiochromic film dosimetry

Radiochromic film is a good dosimeter choice for patient QA for complex treatment techniques because of its near tissue equivalency, high spatial resolution and established method of use. Commercial scanners are typically used for film dosimetry, with Epson scanners being the most common. Radiochromic film dosimetry is not straightforward having some well-defined problems which must be considered, one of the main ones being the Lateral Response Artefact (LRA) effect. Previous studies showed that the contributing factors to LRA are from the structure of the active ingredients of the film and the components and construction of the flatbed scanner. This study investigated the effect of the scanner lens on the LRA effect, as part of a wider investigation of scanner design effects and uncertainties. Gafchromic EBT3 films were irradiated with 40 × 40 cm2 field size 6 MV beams. Films were analysed using images captured by a Canon 7D camera utilising 18 mm, 50 mm and 100 mm focal length lenses compared to images scanned with a conventional Epson V700 scanner. The magnitude of the LRA was observed to be dependent on the focal length of the lens used to image the film. A substantial reduction in LRA was seen with the use of the 50 mm and 100 mm lenses, by factors of 3–5 for the 50 mm lens and 4–30 for the 100 mm lens compared to conventional desktop scanner techniques. This is expected to be from the longer focal length camera lens system being able to collect more light from distant areas compared to the scanner-based system. This provides an opportunity to design film dosimetry systems that minimise this artefact.

Studies on the tissue and water equivalence of some 3D printing materials and dosimeters

The tissue/water equivalent properties of phantom materials and dosimeters are necessary to carry out quality assurance (QA) and dosimetry in radiation medicine such as diagnostic radiology, imaging, nuclear medicine, radiotherapy, etc. In this work, we studied fifteen various biological tissues and water-equivalence properties of some 3D printing materials, gel, and film dosimeters in terms of their effective atomic number (Zeff) over the photon energy range of 10 keV–20 MeV. The Zeff was generated with the help of the Phy-XTRa software. Results found that the various tissue/water equivalence properties of all the studied samples varied with respect to photon energy and the elemental composition. The film dosimeters EBT2-EBT3-HD V2-MD V3-EBT XD and 3D printing materials ABS, PLA, HIPS, PVA, PC,etc and gel PAGAT-NIPAM-MAGIC-MAGAT-FXG showed tissues/water equivalence properties.The presented results will be useful for selecting the appropriate 3D printing materials/dosimeters for the QA and dosimetry in radiation medicine. Adjustment of the elemental composition during the manufacture of phantom/dosimeter may improve the tissue equivalence properties further.

Effect of voxel size in cone-beam computed tomography on surface area measurements of dehiscences and fenestrations in the lower anterior buccal region

ObjectivesThis study aims to assess whether different voxel sizes in cone-beam computed tomography (CBCT) affected surface area measurements of dehiscences and fenestrations in the mandibular anterior buccal region.Materials and methodsNineteen dry human mandibles were scanned with a surface scanner (SS). Wax was attached to the mandibles as a soft tissue equivalent. Three-dimensional digital models were generated with a CBCT unit, with voxel sizes of 0.200 mm (VS200), 0.400 mm (VS400), and 0.600 mm (VS600). The buccal surface areas of the six anterior teeth were measured (in mm2) to evaluate areas of dehiscences and fenestrations. Differences between the CBCT and SS measurements were determined in a linear mixed model analysis.ResultsThe mean surface area per tooth was 88.3 ± 24.0 mm2, with the SS, and 94.6 ± 26.5 (VS200), 95.1 ± 27.3 (VS400), and 96.0 ± 26.5 (VS600), with CBCT scans. Larger surface areas resulted in larger differences between CBCT and SS measurements (− 0.1 β, SE = 0.02, p < 0.001). Deviations from SS measurements were larger with VS600, compared to VS200 (1.3 β, SE = 0.05, P = 0.009). Fenestrations were undetectable with CBCT.ConclusionsCBCT imaging magnified the surface area of dehiscences in the anterior buccal region of the mandible by 7 to 9%. The larger the voxel size, the larger the deviation from SS measurements. Fenestrations were not detectable with CBCT.Clinical relevanceCBCT is an acceptable tool for measuring dehiscences but not fenestrations. However, CBCT overestimates the size of dehiscences, and the degree of overestimation depends on the actual dehiscence size and CBCT voxel size employed.

Surface channel patterned and endothelialized poly(glycerol sebacate) based elastomers.

Prevascularization of tissue equivalents is critical for fulfilling the need for sufficient vascular organization for nutrient and gas transport. Hence, endothelial cell culture on biomaterials is of great importance for researchers. Numerous alternate strategies have been suggested in this sense, with cell-based methods being the most commonly employed. In this study, poly (glycerol sebacate) (PGS) elastomers with varying crosslinking ratios were synthesized and their surfaces were patterned with channels by using laser ablation technique. In order to determine an ideal material for cell culture studies, the elastomers were subsequently mechanically, chemically, and biologically characterized. Following that, human umbilical vein endothelial cells (HUVECs) were seeded into the channels established on the PGS membranes and cultured under various culture conditions to establish the optimal culture parameters. Lastly, the endothelial cell responses to the synthesized PGS elastomers were evaluated. Remarkable cell proliferation and impressive cellular organizations were noticed on the constructs created as part of the investigation. On the concrete output of this research, arrangements in various geometries can be created by laser ablation method and the effects of various molecules, drugs or agents on endothelial cells can be evaluated. The platforms produced can be employed as an intermediate biomaterial layer containing endothelial cells for vascularization of tissue-engineered structures, particularly in layer-by-layer tissue engineering approaches.

Small static radiosurgery field dosimetry with small volume ionization chambers

PurposeTo evaluate the response of the four smallest active volume thimble type ionization chambers commercially available (IBA-dosimetry RAZOR Nano Chamber, Standard Imaging Exradin A16, IBA-dosimetry CC01 and PTW T31022) when measuring SRS cone collimated Flattening Filter Free (FFF) fields. MethodsWe employed Monte Carlo simulation for calculating correction factors as defined in IAEA TRS-483. Monte Carlo simulation beam model and ion chamber geometry definitions were supported by an extensive set of measurements. Type A and B uncertainty components were evaluated. ResultsCommissioning of Monte Carlo 6 MV and 10 MV FFF beam models yielded relative differences between measured and simulated dose distributions lower than 1.5%. Monte Carlo simulated output factors for 5 mm SRS field agree with experimental values within 1% local relative difference for all chambers. Smallest active volume ion chamber (IBA-dosimetry RAZOR Nano Chamber) exhibits smallest correction, being compatible with unity. Correction factor combined uncertainties range between 0.7% and 0.9%. Smallest uncertainties were recorded for smallest and largest active volume ion chambers, although the latter exhibited largest correction factor. Highest contribution to combined uncertainty was type B component associated with beam model initial electron spatial Full Width Half Maximum (FWHM) uncertainty. ConclusionsAmong the investigated chambers, the IBA RAZOR Nano Chamber was found to be an excellent choice for narrow beam output factor measurement since it requires minimum correction (in line with IAEA TRS-483 recommendations). This is caused by its tiny size and tissue equivalence materials which produce minimum volume averaging and fluence perturbation.

Features of PABIGnx 3D Polymer Gel as an Ionising Radiation Dosimeter.

This work presents the features of the PABIGnx 3D polymer gel dosimeter. It consists of two cross-linkers: poly(ethylene glycol) diacrylate (PEGDA), as one biacrylic component, and N,N′-methylenebisacrylamide (MBA), which is another cross-linker often used in 3D dosimeters. Additionally, it contains oxygen scavenges of copper sulfate pentahydrate and ascorbic acid. All ingredients are embedded in a physical gel matrix of gelatine. Upon irradiation, the biacrylic cross-linking agents (PEGDA and MBA) undergo radical polymerisation and cross-linking, which is manifested by the appearance of the opacity of the intensity related to the absorbed dose. PABIGnx was irradiated with an oncological source of ionising radiation, and analysed by using a nuclear magnetic resonance (0.5 T). The following characteristics were obtained: (i) linear and dynamic dose-response of 0.5 to ~18 Gy and 40 Gy, respectively, (ii) dose sensitivity of 0.071 ± 0.001 Gy−1 s−1, (iii) integral 3D dose distribution for at least 24 days after irradiation, (iv) adequate batch-to-batch reproducibility, (v) dose-response independent of irradiation with 6 MV photons, 15 MV photons, 6 MV photons FFF of 0.0168–0.1094 Gy/s dose rates, and (vi) soft tissue equivalence. The study showed that the features of PABIGnx confirm its suitability for use in 3D radiotherapy dosimetry.

Extracorporeal Shock Wave Therapy Improves In Vitro Formation of Multilayered Epithelium of Oral Mucosa Equivalents.

Oral mucosa is used in various surgical fields as a graft for the reconstruction of tissue defects. Tissue engineering of oral mucosa equivalents using autologous cells represents a suitable less burdensome alternative. The survival of the multilayered epithelium is essential for the functionality of the tissues in vivo. To ensure its functionality after transplantation, mucosa equivalents in vitro were subjected to extracorporeal shock wave therapy (ESWT) to determine whether this treatment stimulated the formation and differentiation of the epithelium. Mucosa equivalents treated with ESWT were examined for cellular metabolic activity using AlamarBlueTM assay. The formation of vascular structures, basement membrane, and multilayered epithelium were examined using confocal fluorescence microscopy and immunohistochemistry. The potential ingrowth in vivo was simulated using the chorioallantoic membrane model (CAM assay) in ovo. ESWT on culture day 19 of oral mucosa equivalents resulted in slightly increased cellular metabolic activity. The in vitro development of basement membrane and multilayer epithelium was stimulated by ESWT. Additionally, in the CAM assay, ESWT led to a more pronounced multilayered epithelium. Thus, ESWT stimulated the formation of a more distinct and differentiated multilayered epithelium of oral mucosa equivalents in vitro and might increase the chance of efficient ingrowth, survival, and functionality of tissue equivalents in vivo.

Computed tomography tissue equivalence of 3D printing materials

IntroductionAdditive production refers to the process of prototyping, which allows the production of highly complex medical devices and products. Interpretation of additive manufacturing (AM) material in Computed Tomography (CT) has not been widely investigated. The aim of this study was to determine the CT number values of commercially available fused deposition modelling (FDM) and stereolithography (SLA) AM materials. MethodsTotal of 15 AM materials, 7 FMD and 8 SLA, were selected and scanned on CT to determine the HU value and appearance on the images. All test object were designed as rectangular blocks and after their production physical description were calculated. AM materials were scanned on CT operating at 80, 100, 120 and 135 kV. ResultsAll materials correspond to a certain human tissue and they have uniformity when printed with 100% infill. CT number ranged from a minimum of −188.0 HU to a maximum of 189.1 HU, for FDM materials, and from −15.8 HU to 167.3 HU, for SLA materials. ConclusionKnowing the CT number of an AM materials can allow the design of medical or rehabilitation products with a specific appearance on CT images. Analysed and collected data can find application in the design and manufacture of immobilization devices that can be easily distinguished from other materials or human tissue. Implications for practiceThis study provides information that can be used in the design and fabrication of anthropomorphic diagnostic and therapeutic phantoms. There is significant potential for the use of AM material for sophisticated test objects when used in medical image modality testing. Knowing actual CT numbers of frequently used AM materials allows manufacturing anthropomorphic phantoms to investigate radiation doses in diagnostic radiology and radiotherapy.

Think outside the box: 3D bioprinting concepts for biotechnological applications – recent developments and future perspectives

3D bioprinting – the fabrication of geometrically complex 3D structures from biocompatible materials containing living cells using additive manufacturing technologies – is a rapidly developing research field with a broad range of potential applications in fundamental research, regenerative medicine and industry. Currently, research into 3D bioprinting is mostly focused on new therapeutic concepts for the treatment of injured or degenerative tissue by fabrication of functional tissue equivalents or disease models, utilizing mammalian cells. However, 3D bioprinting also has an enormous potential in biotechnology. Due to the defined spatial arrangement of biologically active (non-mammalian) cells in a biomaterial matrix, reaction compartments can be designed according to specific needs, or co-cultures of different cell types can be realized in a highly organized manner to exploit cell-cell interactions. Thus, 3D bioprinting technology can enable new biotechnological concepts, for example, by implementing perfusion systems while protecting shear sensitive cells or performing cascaded bioreactions. Here, we review the use of 3D bioprinting to manufacture defined 3D microenvironments for biotechnological applications using bacteria, fungi, microalgae, plant cells and co-cultures of different cell types. We discuss recent approaches to apply 3D bioprinting in biotechnological applications and – as it is a particular challenge – concepts for the real-time monitoring of the physiological state, growth and metabolic activity of the embedded cells in 3D bioprinted constructs. With these insights, we outline new applications of 3D bioprinting in biotechnology, engineered living materials and space research.