Search Results (70)

Regenerated cellulose is a promising tribopositive material for sustainable triboelectric nanogenerators (TENGs), although its electrical output remains sensitive to surface and interfacial properties. In this study, regenerated cellulose was modified using atomic layer deposition (ALD) of Al₂O₃, TiO₂, and ZnO to investigate how nanoscale oxide coatings influence triboelectric performance against a tribonegative PTFE counter layer. Two deposition regimes were examined: 7 ALD cycles, representing the early stage of ALD growth, and 200 cycles, representing a more developed coating regime. Triboelectric measurements, dielectric spectroscopy, structural characterization and contact angle analysis, were used to evaluate how ALD modification influences the electrical response of regenerated cellulose. All ALD-modified samples exhibited increased surface charge density and power output compared to unmodified cellulose, while also showing improved retention of triboelectric performance at elevated relative humidity. The 7-cycle samples consistently outperformed the corresponding 200-cycle coatings under low-humidity conditions, whereas the 200-cycle ZnO sample exhibited the highest humidity stability. No direct correlation between wettability and triboelectric output was observed. The results suggest that relatively small interfacial modifications introduced by ALD are sufficient to influence both the triboelectric response and humidity-dependent charge dissipation behavior of regenerated cellulose. Full article

Glitter is a distinctive and largely overlooked form of primary microplastic. Unlike more commonly studied microplastics, glitter particles are typically flat, highly reflective, multi-layered, and are composed of polymers such as polyethylene terephthalate, polyvinyl chloride with metallic coatings and a wide range of additives. In response to regulatory restrictions on intentionally added microplastics and increasing consumer demand, “eco-friendly” alternatives based on modified regenerated cellulose, cellulose nanocrystals, or mica have been introduced, although their environmental safety remains insufficiently characterized. This review synthesizes current knowledge on the environmental occurrence and ecotoxicological effects of both conventional and biodegradable glitters. A systematic literature search in Scopus identified 15 peer-reviewed experimental studies meeting predefined inclusion criteria. Evidence spans a wide range of taxa, including bacteria (i.e., Aliivibrio fischeri), microalgae and cyanobacteria (i.e., Phaeodactylum tricornutum, Raphidocelis subcapitata, Microcystis aeruginosa), aquatic plants (i.e., Lemna minor, Egeria densa), marine and freshwater invertebrates as crustaceans (i.e., Daphnia magna), bivalves (i.e., Mytilus galloprovincialis), sea urchins (i.e., Paracentrotus lividus), brine shrimp (Artemia sp.) and terrestrial soil fauna (Eisenia fetida, Folsomia candida). Results indicate that glitter cannot be treated as a uniform stressor: biological responses vary markedly with particle size, shape, colour, polymer type, additive composition, and weathering time, and leachates often exert stronger effects than intact particles. Reported impacts include impaired photosynthesis and growth, oxidative stress, developmental abnormalities, altered energy metabolism, and reduced reproduction. Substantial gaps remain regarding environmental concentrations, ageing processes, mixture effects, and long-term ecological consequences, particularly for biodegradable glitters. Addressing these gaps will require realistic exposure scenarios, mesocosm and field studies, and integrated chemical–biological approaches to support robust risk assessment and safer material design. Full article

N-methylmorpholine N-oxide (NMMO monohydrate) is widely used for cellulose fibre production, as in the Lyocell process. However, fibre spinning from denim wastes remains significantly more complex due to its higher viscosity, the presence of indigo dye, and NMMO’s temperature sensitivity. These factors together create serious challenges for denim dissolution and fibre regeneration. This study presents a comprehensive rheological and structural characterisation of regenerated cellulose fibres derived from waste denim dissolved in NMMO. Oscillatory and steady-state rheological tests were conducted across concentrations (4–8 wt%) and temperatures (60–90 °C) to determine optimal spinning conditions. A 6% denim/NMMO solution at 80 °C displayed the most favourable rheological balance within the investigated concentration window (4–8 wt%), moderate complex viscosity, well-defined viscoelastic transitions, and a Tan δ value (~0.94) consistent with stable jet formation in air-gap spinning. Steady shear tests confirmed strong shear-thinning behaviour and mechanical predictability, essential for spinneret extrusion. Thermal ramp experiments validated 80 °C as the upper safe limit, balancing flow processability with structural integrity while avoiding solidification or NMMO degradation. The identified rheological parameters fall within ranges reported for spinnable cellulose dopes in air-gap spinning systems, suggesting strong potential for fibre formation under controlled conditions. These findings establish a robust rheological framework for denim-derived cellulose in NMMO and provide a foundation for future investigations into controlled fibre spinning and process scale-up in sustainable textile recycling. Full article

Hemostatic biomaterial agents are widely used during surgery and trauma care to control bleeding, yet their effects on wound healing remain incompletely understood. This study evaluated the impact of oxidized non-regenerated cellulose (ONRC), oxidized regenerated cellulose (ORC), and a gelatin-based hemostat (GELA) on wound healing at 14 and 30 days in a mouse model. Full-thickness wounds were created in C57BL/6J mice (n = 192) and compared to sham controls. Tissue samples were analyzed histologically, supported by immunohistochemistry for Ki-67 and α-SMA and qPCR for VEGF, TGF-β, and FGF-2. Histology demonstrated preserved tissue architecture across groups with progressive resorption of cellulose-based materials, whereas GELA showed localized fibrous structures and enhanced extracellular matrix formation. At day 14, no significant differences were observed in proliferation, contraction, VEGF, or FGF-2 expression; however, TGF-β was significantly reduced in the ORC group. By day 30, GELA significantly increased epidermal proliferation, while contraction markers were elevated in both GELA and ORC. VEGF expression was reduced in GELA and ORC, whereas ONRC showed increased TGF-β expression. FGF-2 remained unchanged across groups. All investigated hemostatic materials were well tolerated during the early postoperative phase (up to day 14), indicating short-term biocompatibility within the scope of this model. In contrast, material-specific differences in cellular activity and growth factor expression became apparent during the later remodeling phase (day 30). These findings suggest differential effects on cellular and molecular aspects of tissue remodeling; however, no conclusions can be drawn regarding overall healing quality or clinical safety, as no quantitative macroscopic or functional outcome measures were assessed. Full article

Oxidized cellulose (OC) and oxidized regenerated cellulose (ORC) are bioabsorbable polysaccharide-based materials widely used in surgery for topical hemostasis. Beyond their established hemostatic role, increasing attention has been directed toward their potential antimicrobial activity, primarily attributed to local acidification following carboxyl group dissociation. Discussing the possible implications of the antibacterial properties of OC/ORC in veterinary surgical practice, this review critically examines the existing evidence. In vitro studies show that viable bacterial counts are significantly reduced in both Gram-positive and Gram-negative pathogens, including antibiotic-resistant strains. Historical in vivo animal models further support a reduction in bacterial recovery in contaminated tissues treated with OC. However, contemporary veterinary clinical trials specifically evaluating surgical site infection (SSI) outcomes remain limited. Documented limitations include variability in formulation, quantity-dependent degradation kinetics, and the potential for foreign body reactions when excessive material is retained. Current evidence suggests that OC may provide adjunctive antimicrobial effects under controlled experimental conditions, primarily in vitro and in standardized animal models, but these properties should be interpreted with caution, and its role should be integrated within comprehensive infection prevention strategies rather than considered a substitute for established perioperative protocols. Full article

Cadmium contamination of water resources represents a serious environmental and public health challenge, with conventional treatment methods often proving inadequate for industrial-level remediation. In this study, we present a novel, sustainable composite material, functionalized cellulose nanocrystal polyvinyl alcohol zinc oxide ferric chloride (CNC-PVA-ZnOFe) beads for the efficient removal of cadmium from contaminated water. The material integrates adsorption, coagulation, and flocculation mechanisms within a single hybrid platform, with coagulation–flocculation serving as the dominant mechanism given the material’s macroporous structure and limited surface area (1.2–3.3 m²/g). Functionalized cellulose nanocrystals provide supporting adsorptive sites for metal binding, while a PVA matrix incorporating ZnOFe improves structural integrity, mechanical stability, and coagulation performance. Characterization confirmed successful functionalization, enhanced thermal stability, and a macroporous structure (12–52 nm pores) conducive to floc entrapment, though with limited surface area (1.2–3.3 m²/g) for conventional adsorption. Under optimized conditions (pH 7–10, initial Cd²⁺ concentration of 100 mg/L, coagulant dose of 0.1 g, and sedimentation time of 60 min), the functionalized CNC-PVA-ZnOFe beads achieved a cadmium removal efficiency of 78%, achieving significantly higher cadmium removal efficiency than traditional coagulants, such as aluminum sulfate (69%). The beads also demonstrated good reusability, retaining 85% removal efficiency after five regeneration cycles. This work presents a scalable, eco-friendly material for cadmium removal under controlled laboratory conditions using synthetic solutions. However, further evaluation in real wastewater matrices containing competing ions and organic matter is necessary to establish practical applicability for water treatment applications. The study highlights the combined potential of multifunctional hybrid materials while acknowledging the need for validation under environmentally relevant conditions. While the results indicate successful integration of multiple removal mechanisms, direct validation of synergistic interactions through techniques such as zeta potential and XPS analysis remains an important direction for future research. Full article

The persistence of water-soluble polymers such as polyvinylpyrrolidone (PVP) in aquatic environments presents a major challenge for conventional wastewater treatment. Herein, a sunlight-active TiO₂/activated carbon (TiO₂/AC) composite fabricated via a simple physical mixing route is reported for the synergistic adsorption and photocatalytic mineralization of PVP K30. The optimal composite (2:1 weight ratio) exhibits a high surface area (412 m² g⁻¹) and an integrated anatase–carbon architecture. The process operates through a sequential “adsorb-and-shuttle” mechanism, whereby PVP is first concentrated on the composite in the dark (30.2% removal in 8 h) and subsequently degraded under solar irradiation. This dual function leads to 86.4% PVP removal and 72.1% total organic carbon (TOC) mineralization, demonstrating true polymer destruction rather than mere surface accumulation. The composite demonstrates robust performance in simulated wastewater, retaining over 68% PVP removal and 55% TOC mineralization in a complex matrix containing competing inorganic ions and natural organic matter. Spectroscopic and thermogravimetric analyses confirm PVP chain scission and near-complete removal of adsorbed residues. An optimized ethanol-washing protocol enables effective catalyst regeneration, with the composite retaining 85% of its initial activity after five cycles. A detailed techno-economic analysis confirms the economic viability of this regeneration strategy at industrial scales (>1000 kg/year), projecting cost savings exceeding 60% compared to fresh catalyst use. Importantly, the PVP-loaded spent TiO₂–AC was successfully repurposed as an electrocatalyst for the urea oxidation reaction, achieving a high current density of 163.7 mA cm⁻², which surpasses the performance of the pristine composite. The greenness of the overall process was validated using analytical eco-scale (ESA), method volume intensity (AMVI), and white analytical chemistry (WAC) metrics. Overall, this work presents a sustainable, solar-driven platform that advances a circular economy model, integrating effective polymer wastewater remediation with subsequent energy valorization of the spent material. Full article

Hemostatic biomaterials are widely used in surgical and trauma settings, yet their influence on early wound healing remains incompletely understood. This in vivo study investigated the effects of cellulose- and gelatin-based hemostatic biomaterials on early wound healing using a murine skin wound model. Oxidized non-regenerated cellulose (ONRC), oxidized regenerated cellulose (ORC), and a porcine gelatin-based matrix (GELA) were left in situ following standardized subcutaneous implantation and compared with sham-treated controls. Tissue responses were analyzed at postoperative days 3 and 7 using histology, immunohistochemistry, and quantitative real-time polymerase chain reaction (qPCR). Cellulose-based materials persisted as eosinophilic remnants, whereas fibrous matrix structures and enhanced extracellular matrix deposition were observed in the GELA group. Immunohistochemical analysis revealed increased cluster of differentiation 68 (CD68)–positive macrophage presence in the ORC group at day 3 and in the GELA group at day 7, indicating biomaterial-dependent modulation of macrophage involvement during early wound healing. Expression of Kiel 67 (Ki-67), a marker of cellular proliferation, was significantly elevated in the epidermis of the GELA group at day 7, suggesting enhanced proliferative activity during the reparative phase. In contrast, no significant differences were detected in the expression of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), or cluster of differentiation 14 (CD14) between groups. Overall, none of the investigated biomaterials impaired early wound healing, while the gelatin-based material demonstrated features consistent with enhanced reparative cellular responses without excessive inflammation. Full article

Background and Objectives: Intraoperative bleeding during neurosurgical procedures poses a significant risk by increasing morbidity and mortality, obscuring the surgical field and prolonging operative time and hospitalization. Effective hemostasis is therefore essential, frequently necessitating the use of topical hemostatic agents. This study aimed to evaluate the performance of a plant-derived oxidized regenerated cellulose (ORC) hemostatic agent StypCel™ Absorbable Hemostat (Medprin Regenerative Medical Technologies Co., Ltd.) in various neurosurgical interventions, including intracranial tumor resections, spinal surgeries, trigeminal neuralgia operations, cerebrospinal fluid fistula repair and ventriculoperitoneal shunt implantation. The study aimed to assess its performance in these procedures due to the high risk of intraoperative bleeding and the challenges of achieving hemostasis in delicate neural structures. Materials and Methods: This prospective, single-arm clinical study included 46 patients who underwent neurosurgical procedures at three neurosurgerical clinics in Riga, Latvia. The primary endpoint was the rate of effective bleeding control achieved within 5 min of StypCel™ application. Safety assessments included monitoring for central nervous system infections (CNSI), intracranial granuloma formation, new-onset neurological deficits, seizures, anaphylactic reactions or device malfunction. All adverse events (AEs) and serious adverse events (SAEs) were documented during the postoperative follow-up. Results: The cohort consisted of 46 patients (29 females and 17 males), including 20 with neoplastic intracranial lesions and 26 with other neurosurgical pathologies. Effective bleeding control within 5 min was achieved in 93.5% of cases (95% CI: 82.1–98.6%). In three patients, bleeding control exceeded 5 min due to unexpected arterial hemorrhage encountered during intracranial tumor resection. No device-related AEs, SAEs, CNSIs or granuloma formations were reported throughout the follow-up period. Conclusions: The findings demonstrate that StypCel™ Absorbable Hemostat is a safe and effective adjunct for achieving intraoperative hemostasis in neurosurgical procedures. Its favorable safety profile and high hemostatic success rate support its clinical utility, particularly for controlling low-pressure venous or capillary bleeding. Further comparative and long-term studies are warranted to validate these results in broader surgical settings. Full article

The development of dressing materials mainly protects the wound, prevents infection, and assists in wound healing. Apart from the most common gauze on the market, different dressing materials can accelerate wound healing. Bacterial cellulose (BC) dressings have had many related studies and applications so far, and other natural or artificial compounds that are beneficial to tissue repair may also be added during the manufacturing process. This study compared the wound healing efficacies of BC dry membrane developed by our team, gauze, commercially available “Tegaderm^TM Hydrocolloid Dressing”, and “AQUACEL^® EXTRA Hydrofiber Dressing”. This study used rats as experimental animals and injured them by scalding. Moreover, Staphylococcus aureus was used to infect wounds to compare the effects on wound healing. We first used NIH-3T3 cells for an in vitro model to confirm that the BC membrane is not harmful to cells. In the animal experiment, wounds were created by scalding and then treated with different dressing materials and doses of S. aureus. After 10 days of treatment, the wound recovery in the BC membrane and AQUACEL^® groups was the most obvious, including angiogenesis in the dermal layer and regeneration of the epidermis layer. Especially without S. aureus infection, inflammatory markers such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression levels were reduced to those of healthy tissue. In conclusion, we confirmed that the BC dry membrane can accelerate wound healing. In the future, it may provide high-efficiency and less expensive options in the dressing market. Full article

The extraction of cellulose from underutilized forest residues can diversify bio-based material supply chains and reduce pressure on commercial pulps. In this study, cellulose was isolated from Tibouchina lepidota (Bonpl.) Baill pruning residues through an alkaline–acid–oxidative protocol, and its suitability for polymeric applications was evaluated. Two granulometric fractions (250 µm and 125 µm) were used; the yields were 4.73 ± 0.12 g and 3.62 ± 0.11 g per 50 g of biomass, equivalent to 90.5% and 92.8% recovery, respectively (fractional remains as bleached pulp after removal of non-cellulosic components). Fourier Transform Infrared spectroscopy (FTIR) showed the disappearance of lignin and hemicelluloses bands and a pronounced β-glucopyranosic signal at 894 cm⁻¹, indicating high purity. Selective solubility in 17.5% NaOH classified the polymer as β-cellulose, suitable for wet spinning and film regeneration. Optical microscopy revealed smooth fibers of 25–50 µm length and 0.5–1 µm diameter, with aspect ratios ≥ 50, indicating favorable morphology for load transfer in composites. Statistical analysis (Shapiro–Wilk, F-test, and Student’s t-test) confirmed the significant influence of particle size on yield (p < 10⁻¹⁵). Overall, T. lepidota residues constitute a viable source of high-purity β-cellulose, whose molecular integrity and microstructure satisfy the requirements of sustainable polymeric manufacturing. Full article

Background/Objectives: Soft tissues are essential for maintaining the function and long-term success of dental implants. In many cases, implant placement necessitates soft tissue augmentation procedures such as free gingival grafts (FGGs) or connective tissue grafts (CTGs) to restore lost gingival architecture. Nevertheless, a significant challenge associated with FGG and CTG is postoperative pain, largely due to morbidity at the palatal donor site. To address this issue, various approaches have been proposed to reduce patient discomfort and promote improved wound healing at the donor site. This study aimed to compare the effectiveness of four different methods for protecting the palatal donor site following free gingival graft harvesting. Methods: A total of 76 patients undergoing implant therapy with an indication for free gingival grafting were selected and divided into four groups based on the method used to protect the palatal donor site: an absorbable gelatin sponge secured with sutures (GS); an absorbable gelatin sponge with sutures and cyanoacrylate tissue adhesive (GS+CTA); oxidized regenerated cellulose combined with cyanoacrylate tissue adhesive (ORC+CTA); and an absorbable gelatin sponge covered with a flowable resin composite and stabilized with sutures (GS+FRC). The effectiveness of each method was evaluated in terms of postoperative pain, bleeding, and wound healing. Results: Although the differences in pain intensity among the groups were not statistically significant throughout the observation period (p > 0.05), the GS+FRC group consistently exhibited the lowest mean pain scores. No statistically significant differences were observed between the groups regarding the incidence of secondary bleeding. The highest mean wound healing rate was recorded in the GS+FRC group (75.95 ± 18.75%), whereas the ORC+CTA group demonstrated the lowest rate (43.66 ± 25.74%). Conclusions: The use of an absorbable gelatin sponge covered with a flowable resin composite and secured with sutures, despite the presented limitations, appears to be a promising approach for palatal wound protection. While this group consistently demonstrated the lowest mean pain scores, differences in pain intensity among the groups were not statistically significant. Nonetheless, it achieved the most favorable outcomes in terms of wound epithelialization. Full article

To successfully prepare cellulose hydrogels through a dissolution–regeneration process, 60 wt% LiBr aqueous solution was used as a green solvent. Carboxyl groups were precisely introduced onto the surface of the cellulose hydrogels through a TEMPO-mediated oxidation reaction, while the three-dimensional network structure and open pore morphology were completely retained. This modification strategy significantly enhanced the loading capacity of the hydrogels with copper nanoparticles (Cu NPs). The experimental results show that the LiBr aqueous solution can efficiently dissolve cellulose, and the TEMPO oxidation introduces carboxyl groups without destroying the stability of the hydrogels. Cu NPs are uniformly dispersed and highly loaded on the surface of the hydrogel because of the anchoring effect of the carboxyl groups. Cu NP-loaded hydrogels exhibit excellent catalytic activity in the NaBH₄ reduction of 4-nitrophenol (4-NP). Cu NP-loaded hydrogels maintain their complete structure and good catalytic performance after five consecutive cycles. Moreover, Cu NP-loaded hydrogels demonstrate high efficiency in degrading organic dyes such as methyl orange and Congo red. This study successfully developed efficient, low-cost, and environmentally friendly Cu NP-loaded hydrogel catalysts through the synergistic effect of LiBr green solvent and TEMPO oxidation modification, providing a feasible alternative to noble metal catalysts. Full article

Nanotopography refers to the intricate surface characteristics of materials at the sub-micron (<1000 nm) and nanometer (<100 nm) scales. These topographical surface features significantly influence the physical, chemical, and biological properties of biomaterials, affecting their interactions with cells and surrounding tissues. The development of nanostructured surfaces of polymeric nanocomposites has garnered increasing attention in the fields of tissue engineering and regenerative medicine due to their ability to modulate cellular responses and enhance tissue regeneration. Various top-down and bottom-up techniques, including nanolithography, etching, deposition, laser ablation, template-assisted synthesis, and nanografting techniques, are employed to create structured surfaces on biomaterials. Additionally, nanotopographies can be fabricated using polymeric nanocomposites, with or without the integration of organic and inorganic nanomaterials, through advanced methods such as using electrospinning, layer-by-layer (LbL) assembly, sol–gel processing, in situ polymerization, 3D printing, template-assisted methods, and spin coating. The surface topography of polymeric nanocomposite scaffolds can be tailored through the incorporation of organic nanomaterials (e.g., chitosan, dextran, alginate, collagen, polydopamine, cellulose, polypyrrole) and inorganic nanomaterials (e.g., silver, gold, titania, silica, zirconia, iron oxide). The choice of fabrication technique depends on the desired surface features, material properties, and specific biomedical applications. Nanotopographical modifications on biomaterials’ surface play a crucial role in regulating cell behavior, including adhesion, proliferation, differentiation, and migration, which are critical for tissue engineering and repair. For effective tissue regeneration, it is imperative that scaffolds closely mimic the native extracellular matrix (ECM), providing a mechanical framework and topographical cues that replicate matrix elasticity and nanoscale surface features. This ECM biomimicry is vital for responding to biochemical signaling cues, orchestrating cellular functions, metabolic processes, and subsequent tissue organization. The integration of nanotopography within scaffold matrices has emerged as a pivotal regulator in the development of next-generation biomaterials designed to regulate cellular responses for enhanced tissue repair and organization. Additionally, these scaffolds with specific surface topographies, such as grooves (linear channels that guide cell alignment), pillars (protrusions), holes/pits/dots (depressions), fibrous structures (mimicking ECM fibers), and tubular arrays (array of tubular structures), are crucial for regulating cell behavior and promoting tissue repair. This review presents recent advances in the fabrication methodologies used to engineer nanotopographical microenvironments in polymeric nanocomposite tissue scaffolds through the incorporation of nanomaterials and biomolecular functionalization. Furthermore, it discusses how these modifications influence cellular interactions and tissue regeneration. Finally, the review highlights the challenges and future perspectives in nanomaterial-mediated fabrication of nanotopographical polymeric scaffolds for tissue engineering and regenerative medicine. Full article

Rapid hemostasis and wound healing are crucial severe trauma treatment. Natural mechanisms often prove insufficient, spurring research for innovative biomaterials. This review focuses on cellulose-based materials, which are promising due to their absorbency, biocompatibility, and processability. The novelty lies in exploring how these materials promote clotting and tissue regeneration. They operate via extrinsic and intrinsic mechanisms. Extrinsically, they create a matrix at the wound to activate coagulation; intrinsically, they maintain clotting factors. Additionally, they aid healing through physical, chemical, and biological means, such as maintaining moisture, incorporating antimicrobial agents, and stimulating cell activity. The innovative fabrication strategies include material selection and chemical modification. Techniques like oxidation enhance performance. Structural engineering methods like freeze-drying and 3D printing optimize porosity and alignment. Cellulose-based dressings are versatile and effective in various forms. They address different wound needs and show benefits like rapid coagulation and tissue repair. This review also covers challenges and future trends, emphasizing the need to enhance mechanical properties and biodegradability. Further, new technologies offer potential improvements to the nanocomposites. Overall, continued research on cellulose-based dressing is vital, and unlocking their potential could revolutionize wound care, providing suitable solutions for trauma management. Full article