The main source of commercial chitosan is the extensive deacetylation of its parent polymer chitin. It is present in green algae, the cell walls or fungi and in the exoskeleton of crustaceans. A novel procedure for preparing chitosan from shrimp shells was developed. The procedure involves two 10-minutes bleaching steps with ethanol after the usual demineralization and deproteinization processes. Before deacetylation, chitin was immersed in 12.5 M NaOH, cooled down and kept frozen for 24 h. The obtained chitosan was characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV, X-ray diffraction (XRD) and viscosimetry. Samples of white chitosan with acetylation degrees below $9\%$ were obtained, as determined by FTIR and UV-first derivative spectroscopy. The change in the morphology of samples was followed by SEM. The ash content of chitosan samples were all below $0.063\%$ . Chitosan was soluble in $1\%$ acetic acid with insoluble contents of $0.62\%$ or less. XRD patterns exhibited the characteristic peaks of chitosan centered at 10 and 20 degrees in $2\theta$ . The molecular weight of chitosan was between 2.3 and 2.8 $\times {10}^5$ g/mol. It is concluded that the procedure developed in the present work allowed obtaining chitosans with physical and chemical properties suitable for pharmaceutical applications.

Radiopacity is sometimes an essential characteristic of biomaterials that can help clinicians perform follow-ups during pre- and post-interventional radiological imaging. Due to their chemical composition and structure, most bioceramics are inherently radiopaque but can still be doped/mixed with radiopacifiers to increase their visualization during or after medical procedures. The radiopacifiers are frequently heavy elements of the periodic table, such as Bi, Zr, Sr, Ba, Ta, Zn, Y, etc., or their relevant compounds that can confer enhanced radiopacity. Radiopaque bioceramics are also intriguing additives for biopolymers and hybrids, which are extensively researched and developed nowadays for various biomedical setups. The present work aims to provide an overview of radiopaque bioceramics, specifically crystalline, non-crystalline (glassy), and nanostructured bioceramics designed for applications in orthopedics, dentistry, and cancer therapy. Furthermore, the modification of the chemical, physical, and biological properties of parent ceramics/biopolymers due to the addition of radiopacifiers is critically discussed. We also point out future research lacunas in this exciting field that bioceramists can explore further.

The growing body of evidence supporting the therapeutic efficacy of psychoactive substances, like psilocybin, has driven significant interest in recent decades due to their low toxicity and potential applications in treating various mental health disorders. However, producing pharmaceutical-grade psilocybin remains challenging, with three primary approaches: chemical synthesis, biosynthesis, and extraction from Psilocybe mushroom fruiting bodies. This systematic review evaluates the extraction and quantification methods for psilocybin and psilocin, aiming to contribute to the development of standardized protocols that ensure compound quality and purity. A total of 25 relevant studies were selected from an initial pool of 9152 publications indexed in platforms such as Scopus, ScienceDirect, Web of Science, and PubMed. The findings indicate that both the extraction method and the choice of mushroom species significantly influence compound yields. Ultrasonic bath extraction was identified as the most efficient technique, particularly for species including Psilocybe cyanescens and Psilocybe cubensis. High-performance liquid chromatography (HPLC) was the most-used method for identifying and quantifying these compounds. Furthermore, polar solvents were critical for effective solubilization, with parameters such as temperature, solvent-to-material ratio, and extraction time playing key roles in optimizing yields. This review serves as a key scientific reference for advancing research, enhancing analytical precision, and ensuring reproducibility through the standardization of extraction and quantification protocols.

Hyaluronic acid (HA) has been an important component in several fields, such as dermal filling, tissue engineering, treatment of the vascular and cartilaginous region, and its application is limited because its excessive use can promote a reduction in cell adhesion, due to its presence of negative charges, characteristic of this material. To solve this limitation, a cationic and anionic material can be used, such as O-Carboxymethylchitosan (O-CMQ), which has a similar chemical structure and similar properties to HA. Therefore, this work aimed to determine the conditions for the synthesis and characterization of O-Carboxymethylchitosan (O-CMQ), and to evaluate its application as an alternative to hyaluronic acid. From the chitosan produced and characterized, the synthesis of O-CMQ was carried out in the proportions 1:1, 1:2 and 1.5:2 (m/v), followed by the characterizations through Visual Analysis, Optical Microscopy (OM), Fourier Transform Infrared Spectroscopy (FTIR), Hydrogen Potential (pH) and Conductivity, Thermogravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC). It was concluded that the synthesis methodology was efficient for the production of O-Carboxymethylchitosan with different properties. The comparison with hyaluronic acid confirmed the chemical, physical and biological similarities between the samples, being promising for application as a substitute for this material.