查看更多>>摘要：Succinoglycan (SG) is an anionic exopolysaccharide produced by some rhizobial microorganisms. In this work, novel temperature/pH-responsive hydrogels based on succinoglycan (SG) directly isolated from Sinorhizobium meliloti and poly(N-isopropylacrylamide) (PNIPAM) were prepared by the radical polymerization method for a drug delivery system. The fabricated SG/PNIPAM (SGPN) hydrogels were characterized using attenuated total reflection-Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and field-emission scanning electron microscopy. As a result, the porous SGPN hydrogels have improved thermal stability due to the interaction with thermally stable SG chains. Rheological and mechanical studies revealed that the storage modulus of SGPN hydrogels decreased with increasing SG concentration, while compressive stress improved up to 8-fold than PNIPAM gel. Swelling experiments showed that the swelling ratio of SGPN hydrogels decreased with increasing temperature, and the swelling ratio of SGPN gel at room temperature was 1.5 times better than that of PNIPAM. The 5-fluorouracil was loaded into SGPN hydrogels to perform a temperature/pH-responsive drug release test. Cytotoxicity test to HEK-293 cell line demonstrated that SGPN hydrogels were nontoxic and biocompatible. It is expected that the SGPN hydrogels could be used as potential biomaterials for biomedical applications as a temperature/pH-dependent drug release system.
查看更多>>摘要：Infertility influences 8-12% of couples globally with male infertility counting for approximately 50% of all infertility cases. Numerous factors such as endocrine disruptors, toxicants, genetics, inflammation, and hormonal disorders are mainly responsible for imparting infertility in males. The available treatments of male infertility are still an unaccomplished task, which is associated with pre-or post-meiotic obstacles to the spermatogenesis process. The development of in vitro spermatogenesis can be considered a potential platform for restoring infertility through a tissue-engineered strategy, which aims to replace the requirement of testes from healthy donors. Despite the innovation in design and fabrication technology, customization of testicular scaffolds is still a vital issue and needs consideration to endorse its relevance for therapeutic benefits. The successful in vitro spermatogenesis process requires appropriate methods to mimic the physiological conditions of the testes and the fabrication of properly designed scaffolds for sperm production. This review discusses the futuristic tissue engineering approaches to treating infertility. It also provides insights into the design and fabrication of testicular scaffolds to produce fertile sperms through three-dimensional (3D) bioprinting and sacrificial template strategies for the construction of tubular structures for the development of testicular organoid and microfluidic devices for supporting the spermatogenesis process.
查看更多>>摘要：Azobenzene-containing polymers (azopolymers) can exhibit a photo-reversible solid to liquid transition which is illustrated by a cyclic softening and hardening of the polymer material upon irradiation. In order to understand the structure-property relationship on this transition, Nitroxide Mediated Polymerization (NMP) was used for the first time to synthesize a series of azopolymers. Four azopolymers bearing various azobenzene groups were designed with different molecular weights. Photo-isomerization properties and photo-reversible solid-to-liquid transitions were studied as function of the molecular weight and structure of the azopolymers. It was found that molecular weights and chemical structure of the azopolymer have both an impact on the features of the reversible solid-to-liquid transition. In particular, the higher the length of the substituent or the linker, the faster the transition. The results obtained in this study help on the one hand to better understand the mechanism of the photo-reversible solid-to-liquid transition and on the other hand to consider the design of novel azopolymers for many applications.
查看更多>>摘要：Designing and preparing memristive materials with multilevel memristive switching characteristics is an effective strategy for improving the data storage capacity of devices. Herein, by grafting a ferrocene-containing polymer (PFMMA) from molybdenum disulfide nanosheets (MoS2 NSs) via polydopamine (PDA)-mediated surface-initiated atom transfer radical polymerization (SI-ATRP), we synthesized a novel two-dimensional nanomaterial, MoS2-PDA-PFMMA. The fabricated Al/MoS2-PDA-PFMMA/ITO sandwich-structured electronic device exhibited asymmetric multilevel resistive switching characteristics, which should give it a larger data storage capacity compared with traditional electrical bistable memristive devices. This work realized multilevel resistive switching in the device by material structure design, which opens up a new perspective for developing memristive devices with ultra-large data storage capacities.
Rana, Md MohosinNatale, GiovanniantonioSiegler, Hector De la Hoz
10页
查看更多>>摘要：A novel route for poly(N-isopropylacrylamide) (PNIPAm) microgel synthesis using the bio-based solvent 2-Methyltetrahydrofuran (2-MeTHF) is described. Functional and chemical characterization of the PNIPAm microgels synthesized in 2-MeTHF indicates that they are equivalent to microgels synthesized using conventional organic solvents. The volume phase transition temperature was 31.7 degrees C, the glass transition temperature was observed at 157 degrees C, and the swelling ratio was 3.7 (dry mass basis). XRD and FT-IR spectroscopic analysis confirmed the successful synthesis of crosslinked PNIPAm microgels. The role of 2-MeTHF as a chain transfer agent in the polymerization can be explained by hydrogen abstraction from the C2 atom position of 2-MeTHF during the chain transfer step of free radical polymerization. An eco-sustainability analysis of the synthesis of PNIPAm microgels in bio-based 2-MeTHF indicates that this route has a much lower carbon footprint than synthesis in conventional solvents, thus providing a more sustainable route for the synthesis of smart microgels for environmental and biomedical applications.
查看更多>>摘要：A dual-drug delivery system (DDDS) based on oxidized alginate (OxAlg) and carboxymethyl chitosan (CMCS) is developed, which can be used for dual-responsive delivery of methotrexate (MTX) and naringin (Nar) for efficient treatment of osteosarcoma. Nar is first loaded onto graphene oxide (GO) through 7C-7C stacking and hydrogen bonding, and then the Nar loaded GO (GO/Nar) is co-encapsulated with MTX by the hydrogel of OxAlg and CMCS generated through Schiff base reaction. The acylhydrazone (-N = C-) bonds between OxAlg and CMCS are prone to be hydrolyzed in an acidic medium, speeding the delivery of the two drugs; meanwhile, GO in this DDDS is an outstanding photothermal agent, leading to near-infrared light (NIR)-responsive delivery of the two drugs. The cumulative release of MTX and Nar can reach 91.09% and 85.69%, respectively, at pH 5.0 with NIR irradiation. The produced hyperthermia under NIR irradiation can result in the ablation of the osteosarcoma cells, and thus the therapeutic efficacy of the DDDS against osteosarcoma is significantly improved via the chemophotothermal synergistic therapy mode, which can be further confirmed by the cytotoxicity test.
查看更多>>摘要：Polydopamine is one of the most promising biomimetic polymers for environmental, biomedical and energy applications. This review presents the current state of the art in the electrochemistry of polydopamine nanomaterials and its applications in the electrochemical analysis and sensing field. First, the mechanism of electrochemical oxidation of dopamine is given concerning the influence of the electrodeposition method and processing conditions, e.g. the pH value is presented, as well as the particularities of polydopamine in electro impedance spectroscopy studies. The electrochemical formation of the polydopamine free-standing thin films is also discussed. Moreover, literature examples of polydopamine for construction or functionalization of the electrochemical sensors for drug traces, disease markers and pesticide contaminants detecting, potentiometric sensing, and wearable strain sensors construction are presented. Finally, we outline the future developments and perspectives of the field.
查看更多>>摘要：In this investigation, to understand the impact on glass transition temperature (Tg) and increase the mechanical properties (elastic and shear modulus), proton conductivity, and single-cell performance, sulfonic acid (-SO3H) functionalized graphene oxide (SGO) was introduced in the perfluorosulfonic acid (PFSA) membranes (Nafion). We conducted atomistic molecular dynamics simulations of fully dry and hydrated PFSA membranes at various hydration levels and SGO loading. The Tg of PFSA polymer composite membranes was increasing with the rising loading percentage of SGO because of the strong connection between the SGO and the PFSA polymer chains in the fully dry states. In addition, the strong antiplasticization effect of water resulted in a further increase of the Tg of hydrated Nafion/SGO-4 composite membranes. The elastic and shear modulus of the Nafion/SGO (Nafion is trade name PFSA membranes) composites increased significantly with SGO loading because of the strong interfacial interaction between SGO and PFSA polymer chains. PFSA membranes loaded with SGO exhibited significant improvement in proton conductivity up to 0.167 S/cm at 90% relative humidity (RH), 95C, 2 wt% SGO loading, which is 1.51 times of recast Nafion membrane. In addition, PFSA composite membrane showed excellent fuel cell performance in terms of maximum power density up to 0.97 W/cm2 at 100% RH, 80 C, 2 wt% SGO loading, which is ~1.3 times of recast Nafion membrane at similar test conditions because of the hygroscopic nature of SGO, the creation of interconnected proton-conducting channels, and the reduction of fuel permeability through the prepared composite membranes.
查看更多>>摘要：In this research, fabrication and characterization of core-shell hydrogel nanofibrous mats containing Polylactic acid/Sage extract in the core and Polyvinylpyrrolidone/Polyvinyl alcohol in the shell, utilizing a novel gas-assisted coaxial electrospinning technique was investigated. The use of an extra gas blowing system allowed to increase core and shell flow rates remarkably and contributed to the higher production of nanofibers in a very short time. To construct the core-shell structure, first, the core solution containing Polylactic acid 8 wt% and Sage extract 10 wt% was prepared. Then the shell solution including Polyvinylpyrrolidone 20 wt% and Polyvinyl alcohol 9 wt% was made and citric acid 2.5 wt% was added as the crosslinking agent. The core and shell solutions were loaded separately in a coaxial spinneret and the gas-assisted coaxial electrospinning was conducted. In the end, the electrospun mats were cured in an oven to obtain core-shell hydrogel nanofibers. The kinetics of the swelling, the release of Sage extract, and the effects of various amounts of crosslinker on the swelling and release process were investigated for core-shell hydrogel nanofibers and then compared to that of the single-core and shell systems. Moreover, the antibacterial assay was performed on the fabricated core-shell hydrogel nanofibers to assess the antimicrobial properties of the electrospun mats. Further evaluations were performed through SEM, TEM, FTIR, DSC, and TGA analyses to determine the morphology and structure of individual systems. The electrospun mats can find excessive applications in biomedical fields as antibacterial dressings for superficial wounds.
查看更多>>摘要：Cardiac patches made up of polymer scaffolds and heart muscle cells have received great attention as a promising construct to repair damaged heart tissue and improve its function. There are various techniques, including solvent casting, electrospinning, and rotary-jet spinning, which are widely used for the fabrication of cardiac patches from natural, synthetic, or natural/synthetic polymers. However, limited control over the structure of patches and poor reproducibility are some of the drawbacks associated with these fabrication methods. Currently, the development of additive manufacturing 3D bioprinting technology has opened a new avenue for tissue engineering applications. 3D bioprinting techniques allow the fabrication of cardiac patches with a flexible design based on the individual patient's needs to be placed in precise geometries as found in native counterparts. Recent research has focused on the improvement and implementing various functionalities of cardiac patches. Electroconductive, drug delivery, 4D, and shape memory cardiac patches are the most recent advances in cardiac patch manufacturing. With all these developments, adhesion of the cardiac patches to heart tissue with a slippery wet surface and under dynamic forces has been challenging. The materials and strategies developed for ideal adhesion to the heart tissue are also reviewed in this paper.
NSTL
Elsevier