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The demand for tissue and organ transplantation worldwide has led to an increased interest in the development of new therapies to restore normal tissue function through transplantation of injured tissue with biomedically engineered matrices. Among these developments is decellularization, a process that focuses on the removal of immunogenic cellular material from a tissue or organ. However, decellularization is a complex and often harsh process that frequently employs techniques that can negatively impact the properties of the materials subjected to it. The need for a more benign alternative has driven research on supercritical carbon dioxide (scCO2) assisted decellularization. scCO2can achieve its critical point at relatively low temperature and pressure conditions, and for its high transfer rate and permeability. These properties make scCO2an appealing methodology that can replace or diminish the exposure of harsh chemicals to sensitive materials, which in turn could lead to better preservation of their biochemical and mechanical properties. The presented review covers relevant literature over the last years where scCO2-assisted decellularization is employed, as well as discussing major topics such as the mechanism of action behind scCO2-assisted decellularization, CO2and cosolvents’ solvent properties, effect of the operational parameters on decellularization efficacy and on the material's properties.

Reports on deep eutectic solvents (DESs), as a new category of green media following ionic liquids (ILs), are increasingly emerging in the literature. Because of the dramatically large number of DESs that will be introduced in the future, it would require much time and expense to experimentally measure their refractive indices. Therefore, proposing a global model that has the ability to estimate the refractive indices of various types of DESs is vital. In this study, it was the goal to develop an accurate, global, simple, and easy-to-use model for estimating the refractive indices of large numbers of DESs having different natures. With this idea in mind, a large up-to-date data bank for DESs was collected, consisting of 1203 data points from 153 different DESs, to develop the model. The proposed model requires critical pressure, molecular weight, and acentric factor as the input parameters. These parameters are calculated by suggested procedures. Therefore, in essence, to be used, the refractive index model does not need any experimental data. The overall absolute average relative deviation, AARD%, of the proposed model for all of the investigated DESs is 1.03%, which indicates high accuracy, as well as generality, for the estimation of the refractive indices of DESs.

Deep eutectic systems (DES) have received considerable attention in the past 5 years of research. Up to 2013 little had been explored over these systems both in which concerns fundamentals and applications. The definition of a deep eutectic system is still controversial and in this manuscript we highlight the different definitions proposed in the literature and discuss what, in our opinion, should be pursued in order to have an agreement in the scientific community studying this field. From the definition of DES to its applications also interesting changes have been observed in the topics published. From electrochemistry to newer applications, such as cryopreservation, the field is evolving as new outcomes on DES properties are unraveled. We herein present and discuss new trends on DES research and present some perspectives on what we consider to be the most promising applications of DES at industrial scale.

Management of degenerative spine pathologies frequently leads to the need for spinal fusion (SF), where bone growth is induced toward stabilization of the interventioned spine. Autologous bone graft (ABG) remains the gold-standard inducer, whereas new bone graft substitutes attempt to achieve effective de novobone formation and solid fusion. Limited fusion outcomes have driven motivation for more sophisticated and multidisciplinary solutions, involving new biomaterials and/or biologics, through innovative delivery platforms. The present review will analyze the most recent body of literature that is focused on new approaches for consistent bone fusion of spinal vertebrae, including the development of new biomaterials that pursue physical and chemical aptitudes; the delivery of growth factors (GF) to accelerate new bone formation; and the use of cells to improve functional bone development. Bone graft substitutes currently in clinical practice, such as demineralized bone matrix and ceramics, are still used as a starting point for the study of new bioactive agents. Polyesters such as polycaprolactone and polylactic acid arise as platforms for the development of composites, where a mineral element and cell/GF constitute the delivery system. Exciting fusion outcomes were obtained in several small and large animal models with these. On what regards bioactive agents, mesenchymal stem cells, preferentially derived from the bone marrow or adipose tissue, were studied in this context. Autologous and allogeneic approaches, as well as osteogenically differentiated cells, have been tested. These cell sources have further been genetically engineered for specific GF expression. Nevertheless, results on fusion efficacy with cells have been inconsistent. On the other hand, the delivery of GF (most commonly bone morphogenetic protein-2 [BMP-2]) has provided favorable outcomes. Complications related to burst release and dosing are still the target of research through the development of controlled release systems or alternative GF such as Nel-like molecule-1 (NELL-1), Oxysterols, or COMP-Ang1. Promising solutions with new biomaterial and GF compositions are becoming closer to the human patient, as these evidence high-fusion performance, while offering cost and safety advantages. The use of cells has not yet proved solid benefits, whereas a further understanding of cell behavior remains a challenge.

Supercritical carbon dioxide has been used as a green solvent due to their well-known potential in biomaterials impregnation. The versatility of this technique enables the loading of implants with Active Pharmaceutical Ingredients which present several benefits when compared with traditional techniques to impregnate active compounds. In this review, we have summarized the recent progresses achieved in supercritical CO2assisted impregnation of active compounds and therapeutic deep eutectic systems for biomedical applications.

Natural Deep Eutectic Systems (NADES) have emerged in the past years as alternative solvents to traditional organic solvents and ionic liquids. NADES are easy to produce, sustainable, biocompatible, eco-friendly, remarkable solubilizing agents, and highly task-specific. The outstanding properties of this new liquid media have attracted the attention of researchers in the last decade in many fields and biotechnology is probably one of the fields where NADES have gained more relevance. Nonetheless, the progress beyond the state of the art in this field is not yet fully explored. Most research papers regarding the use of NADES in biotechnology are related to their use as solubility enhancers for poorly soluble active ingredients, particularly for pharmaceutical applications. However, the applicability of NADES in applications such as cryopreservation, stabilization of proteins and DNA, as well as other biomedical applications, has only recently been explored and presents still a plethora of discoveries to be unravelled. The current developments in this scientific field and future perspectives will be discussed herein.

In this work the possibility of impregnating P(MMA-EHA-EGDMA) with flurbiprofen using a clean and environmentally friendly technology, namely supercritical fluid technology was evaluated. P(MMA-EHA-EGDMA) has been proposed as a promising matrix to be used for intraocular delivery of anti-inflammatory drugs used in eye surgery and flurbiprofen is a non-steroidal antiinflammatory agent. Fundamental studies like, the solubility of the drug in carbon dioxide, as well as the sorption degree of this polymeric matrix in the presence of carbon dioxide have been previously carried out. The aim of this research was to evaluate the effects of these two variables in the impregnation process. Different experimental conditions were tested and the results obtained suggest that the best impregnating conditions for this system are low temperatures and pressures, which at the same time correspond to a lower solubility of the drug in the supercritical fluid and a low swelling of the polymeric matrix. Experiments performed also indicate that the batch impregnation process leads to higher yields of impregnation and according to the release profiles obtained the drug can be released from the matrix up to three months, which presents great advantages for post-surgical treatments.