Weaving the next generation of (bio)materials: Semi-interpenetrated and interpenetrated polymeric networks for biomedical applications

Advances in bioink-based 3D printed scaffolds: optimizing biocompatibility and mechanical properties for bone regeneration

The development of bioink-based 3D-printed scaffolds has revolutionized bone tissue engineering (BTE) by enabling patient-specific and biomimetic constructs for bone regeneration. This review focuses on the biocompatibility and mechanical properties essential for scaffold performance, highlighting advancements in bioink formulations, material combinations, and printing techniques. The key biomaterials, including natural polymers (gelatin, collagen, alginate), synthetic polymers (polycaprolactone, polyethylene glycol), and bioactive ceramics (hydroxyapatite, calcium phosphate), are discussed concerning their osteoconductivity, printability, and structural integrity. Despite significant progress, challenges remain in achieving optimal mechanical strength, degradation rates, and cellular interactions. The review explores emerging strategies such as gene-activated bioinks, nanocomposite reinforcements, and crosslinking techniques to enhance scaffold durability and bioactivity. By synthesizing recent developments, this work provides insights into future directions for bioink-based scaffolds, paving the way for more effective and personalized bone regenerative therapies.

Carboxylated cellulose nanocrystals in semi-interpenetrated network hydrogels and its application in water absorption and antibiotic removal

The water scarcity crisis is currently deepened by the presence of emerging contaminants, such as amoxicillin (AMX), threatening ecosystems and living beings due to their toxicity and bioaccumulation. Due to this, in the present study, superabsorbent hydrogels reinforced with oxidized cellulose nanocrystals (CCNC) were developed, forming semi-interpenetrated networks with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). The CCNCs were obtained by acid hydrolysis and subsequent chemical oxidation to introduce carboxylate groups with two different levels (low and high) of 200 mmol kg-1 (L-CCNC) and 677 mmol kg-1 (H-CCNC), respectively. The effective oxidation of the crystals was confirmed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction, where this reaction did not affect their crystallinity, but reduced their thermal stability. While the obtained hydrogels were characterized chemically, thermally, morphologically and mechanically by FTIR, TGA, scanning electron microscopy, hydration and dynamic compression tests. The incorporation of CCNC to PAMPS increased the thermal stability and modified the surface area of the hydrogels. In addition, the maximum hydration capacity reached 4900 % for PAMPS hydrogels with 10 % H-CCNC, maintaining greater flexibility under compression. Finally, in AMX adsorption studies, parameters such as pH, contact time, initial AMX concentration and amount of adsorbent were evaluated. Achieving a maximum adsorption capacity of 136 mg g-1 with the possibility of reuse in three consecutive adsorption-desorption cycles. These findings highlight the potential of superabsorbent hydrogels reinforced with CCNC as sustainable materials for environmental applications.

Recent Progress in Cellulose-Based Conductive Hydrogels

Cellulose, a widely abundant natural polymer, is well recognized for its remarkable properties, such as biocompatibility, degradability, and mechanical strength. Conductive hydrogels, with their unique ability to conduct electricity, have attracted significant attention in various fields. The combination of cellulose and conductive hydrogels has led to the emergence of cellulose-based conductive hydrogels, which show great potential in flexible electronics, biomedicine, and energy storage. This review article comprehensively presents the latest progress in cellulose-based conductive hydrogels. Firstly, it provides an in-depth overview of cellulose, covering aspects like its structure, diverse sources, and classification. This emphasizes cellulose's role as a renewable and versatile material. The development and applications of different forms of cellulose, including delignified wood, bacterial cellulose, nanocellulose, and modified cellulose, are elaborated. Subsequently, cellulose-based hydrogels are introduced, with a focus on their network structures, such as single-network, interpenetrating network, and semi-interpenetrating network. The construction of cellulose-based conductive hydrogels is then discussed in detail. This includes their conductive forms, which are classified into electronic and ionic conductive hydrogels, and key performance requirements, such as cost-effectiveness, mechanical property regulation, sensitive response to environmental stimuli, self-healing ability, stable conductivity, and multifunctionality. The applications of cellulose-based conductive hydrogels in multiple areas are also presented. In wearable sensors, they can effectively monitor human physiological signals in real time. In intelligent biomedicine, they contribute to wound healing, tissue engineering, and nerve regeneration. In flexible supercapacitors, they offer potential for green and sustainable energy storage. In gel electrolytes for conventional batteries, they help address critical issues like lithium dendrite growth. Despite the significant progress, there are still challenges to overcome. These include enhancing the multifunctionality and intelligence of cellulose-based conductive hydrogels, strengthening their connection with artificial intelligence, and achieving simple, green, and intelligent large-scale industrial production. Future research directions should center around exploring new synthesis methods, optimizing material properties, and expanding applications in emerging fields, aiming to promote the widespread commercialization of these materials.

Functional Semi-Interpenetrating Polymer Networks

Semi-interpenetrating polymer networks (SIPNs) have garnered significant interest due to their potential applications in self-healing materials, drug delivery systems, electrolytes, functional membranes, smart gels and, toughing. SIPNs combine the characteristics of physical cross-linking with advantageous chemical properties, offering broad application prospects in materials science and engineering. This perspective introduces the history of semi-interpenetrating polymer networks and their diverse applications. Additionally, the ongoing challenges associated with traditional semi-interpenetrating polymer materials are discussed and provide an outlook on future advancements in novel functional SIPNs.