Search Results (5,056)

This study focuses on the development and comprehensive evaluation of the physicochemical, mechanical, and biological properties of composites based on polyhydroxybutyrate (PHB), chitosan (Ch), and hydroxyapatite (HA) for biomedical applications. DSC and FTIR spectroscopy showed that the addition of hydroxyapatite did not significantly affect the structure of the materials, but AFM data revealed a change in the surface morphology. Variations in RMS roughness ranging from 13 to 150 nm were observed for chitosan and the composites. The density of the HA-containing samples was 0.06–0.067 g/cm³, which is higher than that of the unfilled composite (0.056 g/cm³). Optimal hydrophilic properties (contact angle 38.9°) and elasticity (damping factor 0.064) were recorded for the sample with 10% HA (PChHA10). The water absorption varied: the addition of chitosan increased the value to 7.5 g/g, compared to 2.7 g/g for pure PHB, while HA slowed the swelling kinetics (more than 180 min). A biodegradation study revealed that samples containing 10–20% HA exhibited the highest stability in an enzymatic environment, while further increases in HA content resulted in increased degradation rates. The PChHA10 is considered to offer the balanced combination of properties. The potential applications of this material in medicine include its use as a scaffold for the in vitro cultivation of osteoblasts and chondrocytes, as well as for implantation in models of bone and cartilage defects in vivo. Full article

This study demonstrates how synthesis conditions and bacterial cellulose (BC) functionalization influence the physicochemical properties and antibacterial performance of BC membranes containing green-synthesized silver nanoparticles (AgNPs). Mint and avocado-seed extracts enabled AgNP formation in aqueous media but differed in composition. UV–Vis screening across pH and temperature revealed inefficient synthesis at acidic pH, whereas higher temperatures produced broader localized surface plasmon resonance (LSPR) bands. Neutral conditions generated the most intense and narrow LSPR signals. Under optimized conditions (pH 7, 23 °C), AgNPs were confirmed by TEM, and their colloidal properties differed between extracts: mint-derived particles exhibited smaller hydrodynamic diameters and lower polydispersity than avocado-derived AgNPs. Two BC functionalization strategies were evaluated: immersion in pre-formed AgNP dispersions and in situ synthesis within the BC matrix. In situ membranes displayed stronger and better-defined LSPR peaks. Agitation released nanoparticles from all BC-AgNP membranes, with smaller species released from in situ systems. Antibacterial assays against E. coli showed greater bactericidal activity for in situ membranes. Avocado-derived in situ BC-AgNPs produced larger inhibition halos and prevented bacterial regrowth in liquid culture. Overall, in situ green synthesis within BC provides an effective route to robust and sustainable antibacterial BC membranes. Full article

Accurate determination of the optical absorption coefficient, ${\mu }_a$, in turbid media is fundamental to biomedical optics and material characterization. Integrating sphere techniques, which measure total transmittance and reflectance, are a standard method for this purpose. However, the inverse models typically employed rely on the assumption of isotropic light propagation. In fiber-structured materials—a common geometry in biological tissue–this assumption often breaks down, leading to significant quantification errors. In this study, we investigated this effect using Monte Carlo simulations and proof-of-concept experiments on mechanically stretched PTFE tape. The medium was modeled as a slab of aligned dielectric cylinders embedded in an isotropic matrix, and the performance of an isotropic inverse model was compared with that of an anisotropic inverse model. The isotropic model showed substantial systematic errors in ${\mu }_a$, with a mean absolute error (MAE) of 19.3%, typical errors between approximately $-40\%$ and 50%, and outliers reaching up to 300%. In contrast, the matched anisotropic model achieved a MAE of 1.2%. Even when the structural parameters of the anisotropic model were perturbed, the MAE remained low at 1.8% for moderate perturbations and 3.9% for severe perturbations. The simulation results therefore indicate that, for the integrating sphere framework considered here, incorporating anisotropic light propagation can improve absorption retrieval more strongly than precise knowledge of all geometric details. Measurements on stretched PTFE tape showed the same qualitative trend and provide proof-of-concept experimental support for the simulation-based findings. Full article

The long-wave infrared band, which at room temperature covers the infrared radiation of humans and objects, has significant applications across various fields including wireless communication, national defense, military, biomedical, and advanced driver assistance systems. Metalens provides a pathway to lightweight, compact, and integrated solutions for infrared imaging and sensing systems, marking an inevitable trend in future development. This study presents a design for a high numerical aperture of 0.89 in a polarization-insensitive all-chalcogenide metalens operating at 10 µm, utilizing the commercially available chalcogenide glass material As₂Se₃ via a transmission phase approach. Building upon this, we have achieved, for the first time, a high numerical aperture of 0.84 for an all-chalcogenide broadband LWIR achromatic metalens operating in the 9.5–10.5 µm range, with significantly improved focusing performance through the application of particle swarm optimization algorithms. The superior performance of the all-chalcogenide LWIR metalens, combined with the advantages of chalcogenide glass over traditional LWIR materials such as Si or Ge—namely, lower cost, reduced optical loss, and a smaller thermo-optic coefficient—suggests it has significant potential for broader applications. Full article

The quantitative analysis of cardio selective beta-blockers, such as the antihypertensive and antiarrhythmic medication acebutolol (ABT), is critical for biomedical and environmental monitoring. This study describes the development of a high-performance electrochemical sensing platform for ABT based on a screen-printed carbon electrode (SPCE) modified with a silver nanoparticle/hexagonal boron nitride (Ag NPs/h-BN) nanocomposite. The morphological and structural properties of the synthesized materials were examined by using a microscopic and spectroscopic techniques. The Ag NPs/h-BN/SPCE demonstrated exceptional electrocatalytic activity toward ABT oxidation, characterized by a significant reduction in overpotential and a substantial enhancement in peak current relative to unmodified and mono-component electrodes. This superior performance is attributed to the synergistic integration of Ag NPs and h-BN, which provides a high density of active sites, an expanded electroactive surface area, and accelerated charge transfer kinetics. Under optimized experimental conditions, the sensor exhibited a broad linear dynamic range of 0.01–284 μM, a remarkably low limit of detection (LOD) of 0.0049 μM, and a high sensitivity of 0.873 µA µM⁻¹ cm⁻² for ABT detection. Furthermore, the platform displayed excellent selectivity in the presence of common interfering species and robust reproducibility (RSD of 4.8%). The practical utility of the Ag NPs/h-BN/SPCE was successfully validated through the precise quantification of ABT in complex biological and environmental matrices. This work provides a versatile strategy for the rational design of metal nanocatalysts confined within h-BN frameworks for the development of advanced electrochemical diagnostic tools. Full article

Objectives: Despite the widespread availability of digital clinical information, timely access to relevant biomedical evidence during routine consultations remains limited in practice. Primary care clinicians, in particular, face significant time constraints that make it difficult to integrate comprehensive literature searches into everyday workflows. This study evaluates whether an ontology-based recommender system can support routine clinical workflows by reducing information retrieval time while preserving the clinically acceptable usefulness of retrieved evidence. We assessed the performance of the HOPE (Health Operation for Personalised Evidence) system compared with realistic manual PubMed searches conducted by physicians. Materials and Methods: We conducted an observational evaluation involving 50 primary care physicians, who independently assessed 30 anonymised, rewritten clinical cases representative of common primary care scenarios. HOPE automatically extracted biomedical concepts from case descriptions using natural language processing and mapped them to Unified Medical Language System (UMLS) ontologies to generate ranked PubMed recommendations. A subset of 10 physicians also conducted manual PubMed searches in line with their usual clinical practice. Article relevance was assessed using a predefined binary criterion, and a reference relevance set was established by consensus among three senior physicians using a pooled document set. Retrieval performance was evaluated using Precision@k, relative Recall@k, and Normalised Discounted Cumulative Gain (NDCG@k). Manual search time was measured using a standardised stopwatch protocol, whereas HOPE response time was logged automatically by the system. Results: Inter-physician agreement in relevance assessment was substantial (Fleiss’ κ = 0.66; 95% CI: 0.61–0.70). HOPE achieved moderate-to-high precision within the top-ranked results (Precision@3 = 0.72), with relative recall increasing as additional documents were considered. Ranking metrics indicated that relevant articles were generally positioned early in the result lists. The mean total retrieval time for manual PubMed searches was 13.3 ± 1.7 min per case, compared with 17.4 ± 2.1 s for HOPE-assisted retrieval (p < 0.001). Conclusions: In a controlled, workflow-oriented evaluation using synthetic clinical cases, HOPE substantially reduced information retrieval time while maintaining clinically acceptable relevance in the retrieved literature. These findings support the use of ontology-based, AI-assisted systems as workflow-support tools to facilitate timely access to biomedical evidence, without replacing clinical judgment. Full article

Rapid and accurate urea detection is of considerable importance in environmental monitoring and biomedical analysis, as abnormal urea levels are associated with water contamination and various health conditions. In this study, a silver nanoparticle-decorated graphene oxide (Ag/GO) composite was synthesized via a simple chemical reduction method. The characterization results confirmed the successful formation of well-crystalline Ag nanoparticles (7.44 ± 1.46 nm) with uniform dispersion on GO, with a Ag loading of 39.1 wt%. The electrochemical performance for urea detection was evaluated in an alkaline medium (0.1 M NaOH) using cyclic voltammetry and chronoamperometry in a three-electrode system. The Ag/GO-modified glassy carbon electrode exhibited a strong electrocatalytic response toward urea oxidation, with a linear detection range of 1–10 mM. The sensitivity and limit of detection (LOD) were 36.8 μA mM⁻¹ and 0.11 mM, respectively. The sensor also demonstrated excellent selectivity in the presence of common interfering species, including uric acid, ascorbic acid, and glucose, along with good reproducibility, repeatability, and stability. Furthermore, the practical applicability of the sensor was assessed in real samples, where satisfactory recovery was achieved in tap water, while reduced performance was observed in milk due to matrix effects. These findings indicate that the Ag/GO composite can serve as an effective alternative electrode material for non-enzymatic electrochemical detection of urea, particularly in wastewater and biological systems. Full article

The valorization of agri-food residues represents an attractive strategy within the circular economy for the development of bio-based materials. In this study, a PLA–cellulose biocomposite (PLACEL10) was developed using cellulose extracted from vine pruning residues (Vitis vinifera, Tintilla de Rota). Cellulose was isolated through sequential acid and alkaline treatments, and the extracted material was incorporated into PLA by melt blending to produce injection-molded specimens. FT-IR confirmed the progressive removal of non-cellulosic components during extraction, while SEM revealed a relatively homogeneous dispersion of cellulose within the polymer matrix. Mechanical characterization showed that PLACEL10 exhibited higher stiffness and tensile strength than the processed PLA and BCF10 controls, although with reduced elongation at break. Biocompatibility was evaluated using hFOB 1.19 osteoblasts by MTS assay, showing viability values above 95% and a proliferative response at 72 h. These results suggest that vine-pruning-derived cellulose can act as an effective reinforcement in PLA and support the potential of this agricultural residue as a feedstock for bio-based composites with possible biomedical and packaging applications. Although the current extraction route involves chemical treatments and cannot be considered fully green, the approach provides a promising route for agricultural waste valorization. Full article

Natural fibers are among the most extensively exploited bio-based materials in industry due to their abundance, affordability, and biodegradability. However, their intrinsic properties often require improvement through chemical, mechanical, or enzymatic treatments to expand their applications. Phosphorylation is a highly effective chemical modification that enables the covalent grafting of phosphate groups onto the fiber backbone. These functionalities enhance hydrophilicity, anionic charge density, swelling capacity, and water uptake, while significantly improving flame-retardant performance. In addition, phosphorylation can reduce energy consumption and production costs in the manufacture of functionalized micro- and nanofibrillated fibers, as the increased swelling facilitates fibrillation. Consequently, phosphorylated fibers are suitable for water treatment, biomedical devices, construction materials, and other advanced materials. Dozens of reagents and various synthetic routes have been explored to perform this reaction, each producing materials with distinct properties. Phosphorus content remains the primary parameter used to assess modification efficiency. This literature review examines existing phosphorylation methods, including reagents, substrates, and characterization techniques, and discusses applications such as flame retardancy, thermal insulation, ion exchange, energy storage, electrodes, and battery recycling. It also briefly addresses key challenges, including limited hydroxyl accessibility, control of the degree of substitution, potential cellulose degradation, and scalability constraints. Full article

Additive manufacturing (AM) has transformed traditional manufacturing by enabling the fabrication of complex geometries and functional components that are difficult or impossible to produce using conventional techniques. Recent advancements have expanded AM capabilities through the integration of multi-material systems, allowing for enhanced performance, customisation, and functionality of manufactured parts. Despite rapid development, there is a limited consolidated understanding of the processes, material combinations, and practical implications of multi-material additive manufacturing (MMAM) across different application domains. This study aims to provide a comprehensive overview of general additive manufacturing processes, with a particular focus on the evolution and implementation of multi-material fabrication techniques. The review draws upon publicly available scientific literature to analyse various AM technologies, material pairing strategies, and process parameters. Comparative analysis is conducted between the additive and conventional manufacturing approaches to highlight advantages and limitations. The findings reveal significant progress in material compatibility, interface bonding, and process integration, enabling the production of multifunctional and performance-optimised components. Diverse applications are identified across aerospace, biomedical, and industrial sectors. MMAM represents a critical advancement in modern manufacturing, offering expanded design freedom and functional integration. Continued research is essential to address the remaining challenges in material compatibility, scalability, and process standardisation. Full article

Curcumin, a plant-derived polyphenolic compound, exhibits diverse pharmacological activities such as antioxidant, anti-inflammatory, anticancer, neuroprotective, and cardiovascular protective effects, and is widely used in food, medicine, and other fields. However, its poor water solubility and easy oxidative degradation limit its extensive application in biomedicine. To solve these problems, a series of biomedical polyurethanes (Cur-PU) with similar molecular weights but different PEG contents were successfully synthesized using HO-PCL-OH and HO-PEG-OH as soft segments and curcumin as a chain extender. The results indicated that increasing the PEG content reduced the T¹_m, T¹_c, and H¹_c of Cur-PU, along with a slower crystallization rate and lower crystallinity. More importantly, a higher PEG content decreased the water contact angle but increased water solubility and water uptake, which, combined with reduced crystallinity, enhanced hydrophilicity, swelling ratio, curcumin release rate, and degradation rate in an enzymatic solution and pH 8.0 buffer. Thus, precise regulation of Cur-PU’s degradation and curcumin release was achieved by controlling the PEG content. Biocompatibility tests confirmed that Cur-PU exhibited excellent antioxidant and antibacterial activities, making it a highly promising biomedical material. Full article

This research systematically investigates the shape memory properties of re-entrant hexagonal negative Poisson’s ratio (NPR) honeycomb structures fabricated via 4D printing, using polyethylene terephthalate glycol (PETG) and polylactic acid (PLA) as comparative materials. Periodic honeycomb models with varied wall thicknesses and structural unit angles were designed, and their effects on shape recovery time and recovery rate were examined. Response surface methodology (RSM) based on a Box–Behnken design was employed to optimize key process parameters, including the wall thickness, structural unit angle, and mold pressing angle. The results demonstrate that PETG exhibits significantly superior shape memory performance compared to PLA, characterized by a shorter recovery time and higher recovery rate under thermal stimulation. Through RSM optimization, the optimal parameter combination was identified as a wall thickness of 0.5 mm, a structural unit angle of 65°, and a mold pressing angle of 135°, which was subsequently validated experimentally, demonstrating a high degree of consistency between predicted and actual outcomes. This study not only clarifies the influence of the structural parameters on the shape memory behavior of NPR honeycomb systems but also provides parameter guidance and a practical experimental basis for the application of PETG in 4D-printed intelligent structures, with potential implications for soft robotics, aerospace, and biomedical devices. Full article

This review comprehensively examines the incorporation of nanoparticles (NPs) into biopolymers for 3D printing in biomedical applications, integrating material design, processing strategies, and translational considerations within a unified framework. Different types of NPs are analyzed regarding their effects on mechanical reinforcement, rheological modulation, and structural organization of biopolymeric matrices. The discussion covers principal additive manufacturing technologies, including extrusion-based systems such as fused deposition modeling (FDM) and direct ink writing (DIW), vat photopolymerization, powder-bed fusion (SLS), and emerging in situ nanoparticle formation approaches, emphasizing how nanoparticle loading and surface functionalization govern yield stress, shear-thinning behavior, viscoelastic recovery, and dimensional fidelity while mitigating agglomeration and optimizing interfacial interactions. Comparative evaluation of compressive modulus, strength, toughness, crystallinity, and porosity establishes structure–property–processing relationships directly linked to printability and functional performance. Biomedical applications are addressed in tissue engineering, biosensing, controlled and targeted drug delivery, and bioimaging, highlighting the balance between bioactivity and manufacturability. Finally, critical challenges—including compatibility, reproducibility, biological safety, long-term stability, regulatory adaptation, and environmental impact—are discussed, alongside future perspectives focused on green nanomaterials, AI-driven predictive formulation design, and digital twins for real-time monitoring and quality control in nano-enabled additive manufacturing. Full article

Fibrin gel, a protein-based polymer naturally generated during coagulation, has garnered attention in the biomedical field for applications such as fibrin glue, due to its specific physical and biological properties. Despite it, low mechanical strength and rapid degradation limited its utilization for biomedical applications. This study presents a reproducible protocol for the synthesis of pure fibrin hydrogels, aimed at achieving predictable structural properties through the precise calibration of fibrinogen and thrombin concentrations. By examining the mechanical and morphological characteristics, as well as the relationship between reagent concentrations and structural integrity, this research assesses impacts on swelling behavior, water absorption, and overall stability. Through a comprehensive analytical approach, we identified an optimal formulation, specifically 2.25 mg/mL fibrinogen and 1.375 U/mL thrombin, that effectively balances structural integrity with high cytocompatibility. The results demonstrate that this calibrated approach ensures high procedural reproducibility and a well-defined hydrogel architecture without the need for exogenous chemical cross-linkers. This work provides a robust methodological framework to overcome the common lack of reproducibility in fibrin-based hydrogel studies, positioning these materials as highly reliable candidates for advanced 3D in vitro models and biomedical applications. Full article