Eduardo Henrique Martins Nunes

This study presents an efficient, scalable method for producing medical‐grade chitosan from Loligo plei squid pens under milder, more sustainable processing conditions. High yields were achieved while preserving the integrity of the polymer chain by using gentle acid demineralization, moderate alkali concentrations, and fewer processing steps than in conventional deacetylation protocols. The resulting chitosan met stringent pharmacopeial standards, exhibiting endotoxin levels below 0.25 EU/mg, residual ash content under 1%, and undetectable levels of heavy metals. Notably, the CHDM45 sample exhibited both high deacetylation (> 85%) and high viscosity (≥ 220 mPa s), making it suitable for advanced biomedical applications, including drug delivery systems, skin wound dressings, and bone engineering scaffolds. Furthermore, high‐quality chitosan was obtained without demineralization by leveraging the inherently low mineral content and purity of the L. plei squid pen. Structural, thermal, and elemental analyses confirmed the effectiveness of the milder process in maintaining desirable material properties. This approach maximizes the value of an underutilized fishery by‐product while minimizing environmental impact, aligning with principles of sustainable resource use and circular bioeconomy. As a result, L. plei emerges as a promising, sustainable source of biomedical‐grade chitosan, supporting innovation in biopolymer‐based materials and responsible waste valorization.

Improving the performance of materials that already possess excellent mechanical properties is one of the most persistent challenges in materials engineering. While carbon‐based nanomaterials such as carbon nanotubes (CNTs) offer remarkable potential for improving polymer nanocomposites, their effectiveness is limited in highly reinforced systems. This limitation is particularly evident in commercial grade rubbers, especially those designed for mining belt covers, which are formulated to provide superior abrasion and tear resistance. In this work, nanocomposites with CNT concentrations up to 8 phr were prepared using both a simplified laboratory formulation and a commercial rubber compound. A pre‐dispersion strategy recently reported was employed, in which the CNTs were dispersed in sulfur to improve their distribution within the rubber matrix. The mechanical and wear properties of both types of nanocomposites were thoroughly analyzed and compared. Although the simplified rubber showed significant improvements in performance, such as a 365% increase in tensile strength, these improvements were less pronounced in the commercial formulation. However, incorporating 5 phr of CNTs into the commercial rubber resulted in a 27% reduction in volume loss during the abrasion test, a notable improvement given the already high performance of the base material. These results demonstrate the potential of CNTs to fine‐tune the properties of advanced rubber composites for demanding industrial applications.

High‐performance rubber‐based composites often contain significant amounts of fillers such as carbon black and silica. Improving the behavior of such composites with small amounts of nanomaterials remains a challenge, and limited progress has been reported in recent years. A critical step in this modification is to achieve uniform dispersion of the nanomaterials within the composite. In this study, carbon nanotubes (CNTs) and reduced graphene oxide (RGO) were pre‐dispersed in sulfur using an innovative method and then incorporated into a commercial rubber. The quality of the synthesized nanomaterials and their interaction with sulfur were evaluated using scanning electron microscopy, Raman spectroscopy, and thermogravimetric analysis. CNTs and RGO nanoplatelets were deposited on the sulfur particle surfaces, achieving extensive coverage. The nanocomposites showed increased crosslink density. The reduced minimum torque observed for these materials compared to rubber suggests a potential lubricating effect of carbon nanomaterials during processing. Mechanical tests revealed the significant impact of the nanomaterials: tear strength increased by 22% in the rubber/CNT nanocomposite, while resilience improved by approximately 20% in all nanocomposites. Contact angle measurements showed a reduction in surface wettability of the nanocomposites compared to rubber after wear, a property that offers potential advantages in applications requiring improved hydrophobicity and durability.

Chitosan has gained considerable attention in recent years as a versatile material with applications in many fields, including food, pharmaceuticals, tissue engineering, and agriculture. The degree of deacetylation (DD) is a critical parameter of the properties and functionality of chitosan, influencing its solubility, bioactivity and suitability for various applications. Accurate determination of DD is crucial as it directly affects the behavior of the material in different environments. However, high-precision methods for DD measurement are often costly and difficult to access, posing a challenge for both academic research and industrial applications. In this study, we evaluated the DD of commercial chitosan using a variety of widely available techniques, including potentiometric titration (PT), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Vis spectroscopy, and X-ray diffraction (XRD). Despite observed differences between methods, all techniques effectively quantified DD, shedding light on factors such as sample solubility, moisture content, baseline correction, and instrument accuracy that contribute to these differences. By demonstrating the feasibility and reliability of simple and accessible techniques for DD determination, this study provides valuable insights for improving the use of chitosan in both research and industry, making these materials more accessible for a wide range of applications.

Although biocomposite foams have been used as wound dressings, achieving accelerated healing with reduced complications requires precise control of exudate absorption and evaporation. This study evaluated the fluid handling capacity, water vapor transmission, and cytotoxicity of novel chitosan/bioactive glass composite foams. Prepared following a simple process, these foams have up to 60% porosity and interconnected pore networks. Cytotoxicity assays confirmed their non-toxicity to L-929 fibroblast cells. The foams demonstrated a liquid absorption capacity of up to 160%, with improved performance at higher levels of bioactive glass. Fluid handling tests showed effective moisture absorption and transfer, making these dressings suitable for the treatment of wounds such as burns and pressure ulcers. The water vapor transmission test confirmed the ability of the foams to promote high exudate removal rates, suggesting that chitosan/bioactive glass composites are promising for wound dressing applications.