A Numerical Study of Fluid Flow in the Porous Structure of Biological Scaffolds

Perfused Platforms to Mimic Bone Microenvironment at the Macro/Milli/Microscale: Pros and Cons

As life expectancy increases, the population experiences progressive ageing. Ageing, in turn, is connected to an increase in bone-related diseases (i.e., osteoporosis and increased risk of fractures). Hence, the search for new approaches to study the occurrence of bone-related diseases and to develop new drugs for their prevention and treatment becomes more pressing. However, to date, a reliable in vitro model that can fully recapitulate the characteristics of bone tissue, either in physiological or altered conditions, is not available. Indeed, current methods for modelling normal and pathological bone are poor predictors of treatment outcomes in humans, as they fail to mimic the in vivo cellular microenvironment and tissue complexity. Bone, in fact, is a dynamic network including differently specialized cells and the extracellular matrix, constantly subjected to external and internal stimuli. To this regard, perfused vascularized models are a novel field of investigation that can offer a new technological approach to overcome the limitations of traditional cell culture methods. It allows the combination of perfusion, mechanical and biochemical stimuli, biological cues, biomaterials (mimicking the extracellular matrix of bone), and multiple cell types. This review will discuss macro, milli, and microscale perfused devices designed to model bone structure and microenvironment, focusing on the role of perfusion and encompassing different degrees of complexity. These devices are a very first, though promising, step for the development of 3D in vitro platforms for preclinical screening of novel anabolic or anti-catabolic therapeutic approaches to improve bone health.

Effect of Lattice Structure and Composite Precursor on Mechanical Properties of 3D-Printed Bone Scaffolds

This article presents an investigation on designing and fabricating scaffolds with different structures, desired porosity, composition, and surface area to volume ratio (SA:V) for orthopedic applications by using the computer-aided design (CAD) and the stereolithography (SLA) 3D printing technique. Different triply periodic minimal surfaces (TPMS) and functionally graded lattice structures (FGLS) were designed based on various cell geometries. Finite element analysis (FEA), tensile and compression tests were carried out, and the results are presented. Two different resin compositions were used to print the models and compare the effect of resin precursors on the mechanical properties of scaffolds. The first was a biodegradable resin made from soybean oil commercially available on the market (made by Anycubic Co.). The second was a mixture of biodegradable UV-cured resin with 5% W/W of hydroxyapatite (HA) and 5% W/W calcium pyrophosphate (CPP). Bio-Hydroxyapatite and Bio-Calcium Pyrophosphate were obtained from eggshells waste and characterized using XRD and FESEM. The obtained data show that adding resin precursors (HA/CPP) slightly decreases the mechanical strength of printed scaffolds; however, considering their extraordinary effect on bone regeneration, this small effect can be ignored, and HA/CPP can be used as an ideal agent in bioscaffolds.

Recent Achievements and Future Challenges in Nanoscience and Nanotechnology

The article presents the investigation results of the formation and synthesis of nanosized materials which were obtained at the Institute of Combustion Problems, many works have been brought to practical use. Investigations of low-temperature soot formation become the basis of nanomaterial synthesis methods, developed at the Institute for Combustion Problems since 1985. Flame can be considered as a chemical reactor to produce target products. The main feature of the processes based on technological combustion is that the target product is formed as a result of the combustion reaction, occurring spontaneously at high temperatures with a high speed without consuming external energy, i.e. due to its own heat. With the development of nanotechnology, new challenges have emerged in the synthesis of nanomaterials under combustion synthesis conditions. Below is a list of works on nanomaterials synthesis carried out at the Institute: complete scheme of soot formation; energy intensive nanocarbon materials; development and study of perovskite photocatalysts for hydrogen evolution; obtaining carbon fibers by the method of electrospinning; obtaining of biologically soluble membranes based on polymeric nanofibres and hydroxyapatite of calcium; synthesis of nanocarbon sorbents for purification of water from heavy metal ions.