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The presented paper investigated the influence of brewers’ spent grain (BSG) extrusionparameters on the photo-oxidative resistance of poly(ε-caprolactone)-based wood polymer composites.Filler samples characterized by the higher melanoidin content were more efficient in hindering of polymerdegradation, inhibiting the decomposition of the polymer amorphous phase. As a result, deteriorationof mechanical performance was limited, which was expressed by the higher values of aging factorfor samples containing BSG extruded at higher temperatures.

Polysaccharides (PSA) have taken specific position among biomaterials for advanced applications in medicine. Nevertheless, poor mechanical properties are known as the main drawback of PSA, which highlights the need for PSA modification. Nanocomposites PSA (NPSA) are a class of biomaterials widely used as biomedical platforms, but despite their importance and worldwide use, they have not been reviewed. Herein, we critically reviewed the application of NPSA by categorizing them into generic and advanced application realms. First, the application of NPSA as drug and gene delivery systems, along with their role in the field as an antibacterial platform and hemostasis agent is discussed. Then, applications of NPSA for skin, bone, nerve, and cartilage tissue engineering are highlighted, followed by cell encapsulation and more critically cancer diagnosis and treatment potentials. In particular, three features of investigations are devoted to cancer therapy

The microstructure design of hydrogel materials offers a broad range of practical applications and is extensively used in flexible sensors, polymer microneedles, microfluidic chips, and other biomedical engineering fields. Among the bio-sourced hydrogels, oligomeric hyaluronic acid (HA) possesses wound healing, anti-tumor, and angiogenesis properties. However, micropatterning soft hydrogels, such as HA-relative hydrogels containing 90% water by weight, continue to pose difficulties for both high precision and micro-scale lithography. The purpose of this study was to compare the photolithography and light-cured inkjet printing methods of methacryloyl HA hydrogel (HAMA-gel) to those for synthetic light-curable polymer resins. Photolithography and light-cured inkjet printing methods with designed scale, high resolution, and little processing times were used to effectively prepare micropatterns of HAMA-gel. The well-shaped micropatterns consisted of parallel channels in tens of micrometers and strip/grid lines in the hundreds of micrometers. Human vein endothelial cells cultured on the material’s surface demonstrated that HAMA-gel had good biocompatibility. The width of the flow channel (10 and 20 µm) was regulated on the surface of the microstructure to allow for simultaneous control of cell growth along the flow channel and groove directions.

We propose a pressure-induced flow (PIF) processing method for the simultaneous enhancement of strength, toughness, and heat resistance of biodegradable poly(butylene succinate) (PBS). The pressure and temperature were systematically adjusted to optimize the tensile strength of PBS. Under the optimized processing conditions, the structured PBS was characterized by relatively high strength of 89.5 MPa, toughness of 21.4 kJ·m−2, and improved heat resistance without deterioration of much of its ductility. Microscopic analyses witnessed denser and highly oriented crystalline domains along the flow direction caused by PIF processing. Detailed crystallization analysis made by 2D-WAXD and 2D-SAXS unraveled the extremely ordered PBS domains, which were featured by a significant increase in the orientation degree from 0.25 for the reference to 0.73 for PIF-processed PBS. Such a highly ordered microstructure substantially boosted the degree of crystallinity and heat-resistance temperature of PBS. We believe that our findings would offer a facile, green, and cost-effective approach for fabricating biodegradable polymers with outstanding properties and performance.

Due to the shortage of petroleum resources, poly(lactic acid) (PLA), a biodegradable polymer, has been widely considered as a replacement for traditional petroleum-based polymers. Therefore, multifunctional PLA composites have become increasingly popular. In this study, conductive carbon nanotubes (CNTs) and magnetic nano-Fe3O4 fillers were melt-blended with PLA. The impact of CNTs and nano-Fe3O4 composition on the electrical and electromagnetic interference (EMI) shielding properties of PLA nanocomposites was investigated in detail by adjusting the CNTs-to-nano-Fe3O4 ratio. When the hybrid filler content was fixed at 10 wt%, the electrical conductivity results indicated that the addition of single CNTs could effectively improve the conductivity of the nanocomposites, while nano-Fe3O4 contribution was hardly noted. A suitable ratio of electromagnetic hybrid fillers can yield excellent synergistic effects in EMI shielding properties. The nanocomposites containing CNTs and nano-Fe3O4 in a 50:50 ratio exhibited excellent electrical conductivity (90.6 S·m−1) and EMI shielding effectiveness (EMI SE ∼ 40.5 dB). This is primarily because CNTs provide good electrical conductivity, but the addition of magnetic nano-Fe3O4 provides additional interfacial polarization and eddy current losses caused by its dielectric and magnetic properties. These properties synergistically result in an impedance mismatch, dielectric loss, and polarization relaxation of the composite materials, improving the shielding properties against electromagnetic waves. Further, it was found that changing the ratio of electromagnetic hybrid fillers also affected electromagnetic wave absorption. When the ratio of CNT-to-nano-Fe3O4 was 25:75, the nanocomposites had an EMI SE of 24.6 dB, and the absorptivity could reach the maximum (40.3%). Thus, this study provides a valuable reference for preparing multifunctional polymer nanocomposites by constructing electromagnetic hybrid filler networks.

Natural rubber (NR) has poor mechanical properties, which limits its practical application. Filler blending is a simple method that improves the inherent properties of natural rubber and expand its applicability. Using the mechanical mixing process, the effects of graphene oxide (GO) and redox graphene (rGO) on the physical properties, electrical conductivity, thermal conductivity, and air permeability of styrene-butadiene rubber (SSBR)/NR composites were studied. The results show that rGO exhibits efficient filler properties in various aspects, for example, the optimal filling amount of rGO and GO was 1.5 phr. In addition, rGO filled SSBR/NR composites showed satisfactory filler dispersibility. Notably, the better dispersibility of rGO was because of fewer hydrophilic functional groups on the surface which were difficult to agglomerate. The increase of rGO and GO content increased the maximum torque (MH) and minimum torque (ML) of the composite material, and decreases tc90 and tc10. The Payne effect of GO/SSBR/NR composites is more obvious than that of rGO/SSBR/NR composites. In addition, we found that the content of rGO (GO) reached saturation at 2phr. Notably, rGO and GO improved the properties of rGO filled SSBR/NR composites such as the tensile strength of rGO/SSBR/NR composites to 23.9 MPa. This shows the potential application of SSBR/NR composites in wearable electronic devices.

The high conductivity and excellent mechanical properties of polymer composites favor their application as piezoresistive strain sensors. However, developing polymer composites with desirable piezoresistance, mechanical and durable properties is challenging. Herein, we developed conductive cellulose/MWCNTs aerogels using the freeze-drying technique. Furthermore, we explored the application of the highly-sensitive piezoresistive polymer composites following supercritical carbon dioxide (ScCO2) foaming, in cellulose/MWCNTs aerogel-thermoplastic polyurethane (TPU) nanocomposites. Conductive polymer composite (CPC) foams exhibited a significantly low percolation threshold (MWCNTs loading of ∼0.07 vol%) and high piezoresistive sensitivity (GF value of 7.84) owing to the low density (∼0.15 g cm−3) of cellulose/MWCNTs, high porosity (90%) and high electric conductivity (2.04 S m−1). The microcellular structure of composite foams was stable with regard to energy loss coefficient and piezoresistance after several compression cycles (1000 cycles). The behavior of the prepared CPC foams under different conditions was evaluated. The findings of the study showed that the piezoresistive sensors can be used in real-time monitoring of human movement.

The complex environment in the bladder weakens the efficacy of intravesical therapy. Hydrogel-based drug delivery systems are poised to revolutionize the delivery of therapeutic agents to bladder lesion sites. This forum article highlights the prospective applications of hydrogels as drug reservoirs in treating chronic bladder diseases.

Rapid detection and identification of Escherichia coli (E. coli) is essential to prevent its quickly spread. In this study, a novel fluorescence probe based on ZnTe quantum dots (QDs) modified by mannose (MAN) had been prepared for the determination of E. coli. The results showed that the obtained QDs showed excellent selectivity toward E. coli, and presented a good linearity in range of 1.0 × 105∼1.0 × 108 CFU/mL. The optimum fluorescence intensity for detecting E. coli was found to be at pH 7.0 with a temperature of 25 °C and incubation time of 20 min. Under these optimum conditions, the detection limit of E. coli was 4.6 × 104 CFU/mL. The quenching was discussed to be a static quenching procedure, which was proved by the quenching efficiency of QDs decreased with the temperature increasing.

To overcome the low mechanical strength and difficult bonding of hydrogels to bones which are the major limitations of hydrogels used in bone-regeneration, a new type of calcium polyphosphate incorporated into bioinspired alginate/polyacrylic acid (CPP/PAA-Alg) hybrid double network (DN) hydrogel with both high strength and enhanced osseointergration was prepared by a two-step polymerization with alginate and polyacrylic acid for bone regeneration. The morphology, mechanical properties, swelling, biocompatibility, osseointegration and osteogenic ability of this CPP/PAA-Alg DN hydrogel were investigated. The results show that CPP/PAA-Alg DN hydrogel with highly porous microstructure possesses high water absorption capacity and highly strength properties which meet the requirements of bone repairing. The results of in vitro studies revealed that the CPP/PAA-Alg DN hydrogels can support the spread of cells and promote the cell proliferation. Animal studies demonstrated that the CPP incorporated would enhance the osseointegration of DN hydrogel with host bone at an early stage after implantation to accelerate the regeneration of bone. This research may provide a new way to develop biocompatible biomaterials with high mechanical strength and good osseointegration to meet the needs of bone regeneration.

Supercritical fluids have been widely used to prepare various polymer nanocomposite foams due to their high-efficiency, rich-resource, and environment-friendly characteristics. In this work, we prepared polystyrene (PS) nanocomposites with different contents of hybrid fillers of nanoclay and nano-calcium carbonate (nano-CaCO3) and then were foamed by batch foaming method using supercritical carbon dioxide as a physical blowing agent. The effect of hybrid nanofillers components and foaming temperature and pressure on the foaming properties and cellular structure of PS nanocomposite foams was systematically investigated. Dynamic rheology results indicated that the complex viscosity and storage modulus were enhanced with the addition of hybrid fillers. Scanning electron microscopic images show that all samples foamed uniformly macrocells under the given conditions. More importantly, the hybrid fillers of nano-CaCO3 and nanoclay exhibit a significant synergistic effect in improving PS foaming properties, which can be ascribed to the different roles of the two fillers during cell nucleation and cell growth. For instance, the PS/0.22/0.88 nanocomposite foamed under the conditions of 20 MPa and 130°C has shown the finest cell structure (higher cell density of 1.91 × 1010 and smaller cell diameter of 2.28 µm) due to the coeffect of the hybrid nanofillers. Finally, the synergistic mechanism of these two nanofillers on PS foaming behavior was discussed.

In this study, a strong and tough high-density polyethylene (HDPE)/hydroxyapatite (HA) nanocomposites with bone-analogues structure was successfully prepared via a simple dynamic-oscillation-shear processing method for biomedical application as bone substitute materials. Dynamic-oscillation-shear flow field was applied by self-made loop oscillatory push-pull molding (LOPPM) equipment. The LOPPM-processed HDPE/HA composites exhibited tremendous increase of tensile strength, modulus and toughness up to 95.1 MPa, 4.2 GPa, 58.4 kJ/m2, respectively, which could be attributed to better dispersion of HA in HDPE matrix and highly ordered shish-kebab structure as evident from DSC, SEM, WAXD and SAXS studies. Meanwhile, the formed hierarchical structure not only showed bone-like structure, but also endowed composites with high strength, modulus and toughness, even close to the human cortical bone. Moreover, in vitro cell culture study was performed on NIH-3T3 fibroblast cells to evaluate the biocompatibility of the composites. The results showed that the produced bone substitutes exhibit good biocompatibility. Besides, using a rabbit calvarial defect model, in vivo testing has shown that a strong and stable interface is developed between the composites and the host bone. Overall, we present a facile and green strategy to generate polymer composites with high strength and toughness and the produced LOPPM-processed HDPE/HA polymer nanocomposites have a great potential for use as load-bearing bone substitute in biomedical application.

In an effort to achieve a high-efficient fire-resistant coating for the flexible polyurethane (PU) foams, a layer-by-layer assembly technique of polyethylenimine (PEI), graphene oxide (GO) and synthetic melanin nanoparticles (SMNPs) was constructed on the surface of PU foams. The preeminent radical scavenging capacity and high-temperature thermal stability of SMNPs enable it to be applied as a flame retardant for the subsequent coating process. Scanning electron microscope (SEM) images indicate that the as-fabricated PEI/GO/SMNPs coatings are uniformly deposited on the PU foam along the cell walls. In contrast with pure and bilayer-coated (BL-coated) PU foams, thermogravimetric analysis (TGA) reveals that the trilayer-coated (TL-coated) foam exhibits a better thermos-oxidative stability and a lower pyrolysis rate with the deposition of PEI/GO/SMNPs nanocoating. In the torch burn test, the flame of PU-1TL foam coated with only one-trilayer PEI/GO/SMNPs is able to self-extinguish and the original shape of the entire foam is intactly preserved. Cone colorimeter tests indicate that the release amount of heat and smoke can be effectively suppressed in the coated foam, and the formation of the highly graphitized char is beneficial to the improvement of the fire-resistant performance. In addition, thermogravimetric analysis/infrared spectrometry (TG-IR) results demonstrate that the volatilization of organic and toxic gases in gas phase are effectively restrained, which can be attributed to the lamellar shield of GO and radical trapping effect of SMNPs. These results illustrate that synthetic melanin material is one of the promising candidates as efficient additive in fire-resistant polymers, and the PEI/GO/SMNPs coatings play a part in gas-solid phase to improve the flame retardancy of PU foams.

Surfaces with stimuli-responsive properties have shown prominent applications in bioengineering, controlled drug release and biosensors in recent years. In this work, we report a surface-initiated reversible addition–fragmentation chain transfer polymerization method to graft azobenzene-containing diblock copolymer (azo-BCP) brushes onto an Indium Tin Oxide (ITO) glass surface. In this method, a sequential azo block serves as the outer layer that controls the closure or opening of the brushes, and the second block (PDMAEMA) acts as the inner layer that switches between swollen and collapsed chain states in response to different pH values and temperatures. Upon exposure to UV light, the ITO surface became more hydrophilic (>10° change of contact angles), and its friction coefficient (0.5–0.9) increased; this suggests a loose aggregation of the azo block. Additionally, the ion conductivity of the ITO surface can be influenced by the aggregation state of the azo-BCP brushes, thus leading to the transportation of light-triggered ions under various pH values and temperatures. This work provides a deep understanding of the surface properties of a sensitive hybrid material upon various stimuli for electrode purpose, thereby paving the way for the development of bioengineering and environmental sensory applications.

Lignin is the most abundant and important macromolecule in organic matter and its yield is second only to cellulose. Lignin is abundant in source, low in price, and has a large number of active groups such as methoxy group and carboxyl group, so it has great utilization value. We used lignin as a carbon source to prepare porous carbon nanosphere (PCN) materials, and in-situ synthesized the MoS2 on its surface. The high specific surface area (∼462.8 m2/g), large pore volume and good electron conductivity of the porous carbon scaffold facilitated the reversible electro-chemical reaction of S towards metallic Li, and thus the nano-hybrid showed a high specific energy and excellent cycle stability which still remained 520 mAh/g after 50 cycles.

Patchable devices that interface with the skin across a wide range of size scales, from cellular level down to molecular level, become increasingly attractive in biomedical research. These devices hold the potential for diagnostic and therapeutic functions with exceptional spatiotemporal precision, continuity, and convenience. Further, they afford new opportunities to integrate cloud-based technology and artificial intelligence for a smarter healthcare system. This article reviews recent advances in materials design and assembly techniques for fabricating various patchable devices, with focuses on electrical, thermal, mechanical, and chemical biosensors as well as transdermal gene and drug delivery platforms. A concluding discussion provides perspectives for future developments and outlooks in clinical applications.

Most biofluids contain a wide variety of biochemical components that are closely related to human health. Analyzing biofluids, such as sweat and tears, may deepen our understanding in pathophysiologic conditions associated with human body, while providing a variety of useful information for the diagnosis and treatment of disorders and disease. Emerging classes of micro/nanostructured bioelectronic devices for biofluid detection represent a recent breakthrough development of critical importance in this context, including traditional biosensors (TBS) and micro/nanostructured biosensors (MNBS). Related biosensors are not restricted to flexible and wearable devices; solid devices are also involved here. This article is a timely overview of recent technical advances in this field, with an emphasis on the new insights of constituent materials, design architectures and detection methods of MNBS that support the necessary levels of biocompatibility, device functionality, and stable operation for component analysis. An additional section discusses and analyzes the existing challenges, possible solutions and future development of MNBS for detecting biofluids.

Heteroatom-doped carbon dots (CDs), due to their excellent photoluminescence (PL) properties, attracted widespread attention recently and demonstrated immense promise for diverse applications, particularly for biological applications. The objective of this feature article is to provide a comprehensive overview of the recent progress in the research and development of heteroatom-doped CDs and a detailed description of the influence of single or co-doping heteroatoms on their PL behavior. The most recent understanding and critical insights into the PL mechanism of heteroatom-doped CDs are also highlighted. Moreover, potential bio-related applications of heteroatom-doped CDs in biosensing, bioimaging, and theranostics are also reviewed. This state-of-the-art review will provide a platform for understanding the intricate details of heteroatom-doped CDs, a summary of the latest progress in the field, and related applications in biology and is expected to inspire further developments in this exciting class of materials.

Application of lignocellulosic fillers in the manufacturing of wood polymer composites (WPCs) is a very popular trend of research, however it is still rarely observed in the case of rotational molding. The present study aimed to analyze the impact of wheat bran content (from 2.5 wt.% to 20 wt.%) on the performance of rotationally-molded composites based on a linear low-density polyethylene (LLDPE) matrix. Microscopic structure (scanning electron microscopy), as well as physico-mechanical (density, porosity, tensile performance, hardness, rebound resilience, dynamic mechanical analysis), rheological (oscillatory rheometry) and thermo-mechanical (Vicat softening temperature) properties of composites were investigated. Incorporation of 2.5 wt.% and 5 wt.% of wheat bran did not cause significant deterioration of the mechanical performance of the material, despite the presence of &lsquo, pin-holes&rsquo, at the surface. Values of tensile strength and rebound resilience were maintained at a very similar level, while hardness was slightly decreased, which was associated with the porosity of the structure. Higher loadings resulted in the deterioration of mechanical performance, which was also expressed by the noticeable rise of the adhesion factor. For lower loadings of filler did not affect the rheological properties. However, composites with 10wt.% and 20 wt.% also showed behavior suitable for rotational molding. The presented results indicate that the manufacturing of thin-walled products based on wood polymer composites via rotational molding should be considered a very interesting direction of research.

Supplemental Material, Supporting_information for Synergetic effect of nanoclay and nano-CaCO3 hybrid filler systems on the foaming properties and cellular structure of polystyrene nanocomposite foams using supercritical CO2 by Xinghan Lian, Wenjie Mou, Tairong Kuang, Xianhu Liu, Shuidong Zhang, Fangfang Li, Tong Liu and Xiangfang Peng in Cellular Polymers

This work presents an ultrasonic-assisted approach for fast impregnation of thermoset and thermoplastic polymers including solvent-free epoxy resins, polydimethylsiloxane resins, and polypropylene into multi-walled carbon nanotube (MWCNT) nanopapers to prepare nanocomposites or prepregs with high loading (>20 wt%) of well-dispersed MWCNTs, not achievable by the conventional compounding or resin transfer molding methods. The approach involves making MWCNTs into macroscopic paper-like sheets (also called “nanopapers”) via a dispersion-filtration method and then impregnating the mesoporous nanopapers with polymeric resins using an ultrasonic infiltration method to form a prepreg or nanocomposite. The formed nanocomposites revealed an excellent combination of mechanical strength, sand erosion and scratch resistance, electrical and thermal properties, and good processing flexibility.

Conductive polymer composite (CPC) foams have been considered as a promising electromagnetic interference (EMI) shielding materials because of the advantages of the lightweight, low-cost and easy preparation process. However, most of the currently reported CPC foams were prepared by batch foaming process. Insight of large-scale and low-cost production of CPC foams, we presented a feasible extrusion foaming strategy of polystyrene (PS) composites with micro-graphite (mGr) or multi-wall carbon nanotube (MWCNT) using supercritical carbon dioxide (Sc-CO2) as the physical blowing agent for EMI shielding application. The composite foams showed elongated cell morphology; meanwhile, the compressive strength and electrical conductivity were significantly increased. These composite foams presented a remarkable high performance of EMI shielding efficiency, corresponding average EMI SE of 22 dB and specific EMI SE of 92 dB/(g/cm3). In comparison between mGr and MWCNT, PS/mGr composite foams showed better EMI SE than that of PS/MWCNT composite foams at the same filler content due to the lower foam density of PS/mGr composite foams. Considering the feasible, large-scale and low-cost production process, these CPC foams are expected to apply in high performance EMI shielding areas.

General purpose plastic materials with high strength and toughness are in great demand for structural engineering applications in recent years. Inspired by the relationship of excellent integration of mechanical performance and hierarchically ordered shish-kebab structure of polymeric materials, a facile and efficient strategy based on the combined effect of strong extensional dynamic oscillatory shear flow and ultra-high-molecular-weight polyethylene (UHMWPE) was developed to fabricate ultra-strong, super-tough and high wear resistance integrated high-density polyethylene (HDPE)-based materials. As a result, the maximum value of tensile strength, modulus and toughness were respectively 3.8, 5.9 and 6.8 times higher than that of neat HDPE, even superior to that of most common engineering plastics. Meanwhile, the wear rate of resultant HDPE-based materials could be reduced from 18.6 to 4.2 mg/MC. Overall, the HDPE-based material with extraordinary integrated strong, tough and high wear resistance properties would have a great potential for the replacement of engineering plastics and application in aerospace, military, tissue engineering, etc.

Three-dimensional (3D) bio-nanocomposite poly (butylene succinate) (PBS)/cellulose nanocrystals (CNC) scaffolds were fabricated by a solvent mixture of chloroform (CF) and methanol (MeOH) via electrospinning technique. Morphological, thermal, mechanical, and hydrophilicity as well as in vitro degradation and biocompatibility properties of the electrospun fibrous bio-nanocomposite scaffolds were investigated. Scanning electron microscopy (SEM) indicated that the average diameter of the electrospun fibers decreased with increase in CNC concentration. The incorporation of CNC not only enhanced the thermostability, and 0.5 wt% and 1 wt% CNC significantly increased the crystallinity of PBS matrix, but also improved the tensile strength, Young's modulus and hydrophilicity of PBS matrix with an optimum 3 wt% CNC. Moreover, it also improved the porosity and decreased the density of the PBS/CNC scaffolds. In vitro degradation results showed that PBS/CNC3 scaffold had better bio-degradation ability, from 4.5% of neat PBS to 13.74% of PBS/CNC3 in 28 days. 3T3 fibroblast cell culture was performed to confirm the good biocompatibility of the scaffolds. Cells were found to proliferate better on the PBS/CNC3 scaffolds, as compared to neat PBS scaffolds in 7 days.

The hierarchical structures from micro- to nano-scale in polymeric materials can dramatically affect their physical properties. Controlling the formation of hierarchical structures in polymers through processing remains a challenge. We present here a green and convenient polymer processing approach to prepare isotactic polypropylene (iPP)/polytetrafluoroethylene (PTFE) nanocomposites with hierarchical superstructures via recently developed loop oscillating push-pull molding (LOPPM) method. By taking full advantage of intense oscillatory shear, the in situ generated PTFE fibrils are refined into nanoscale and well aligned, serving as the central shish to induce the formation of nanohybrid shish-kebab (NHSK) superstructure with iPP crystalline lamellae (kebabs). The structure evolution of NHSK superstructures was further examined using molecular dynamics simulations. The stretched fibrils can promote the kebabs growing into large domains with a more compact and ordered molecular chain configuration, compared to that in systems without fibrils or with flexible fibrils. The well-aligned fibrils and NHSK superstructure play a crucial role in enhancing properties. The prepared iPP/PTFE nanocomposites containing 3 wt% PTFE achieved 197.9% and 36.0% improvement in impact and flexural strength, respectively, as compared with the conventional injection-molded composites. Meanwhile, the LOPPM iPP/PTFE nanocomposites exhibits excellent resistance to thermal deformation under harsh environment (over 150 °C) while fabricates a hydrophobic surface. These findings provide a facile strategy to produce high-performance polymers from judiciously controlled sample preparations.