One of the current strategies to overcome methicillin-resistant Staphylococcus aureus (MRSA) and to minimise the need for new antibiotics is the application of adjuvant in antibiotic therapy. In the present work, cefotaxime (CTX), a third-generation antibiotic was successfully incorporated into a nanofiber mat and applied in combination with an adjuvant including boric acid (BA), borax (BX), and phenylboronic acid (PBA). The antibacterial activity of the developed formulations against Staphylococcus aureus strains including methicillin-susceptible S. aureus MSSA (ATCC® 25923™), oxacillin-sensitive S. aureus OSSA (ATCC® 29213™) and methicillin-resistant S. aureus MRSA (ATCC® 43300™) were evaluated by Kirby–Bauer disc diffusion and minimum inhibitory concentration (MIC) methods. PBA markedly decreased the MIC of CTX from 16 µg ml-1 to 0.125 µg ml-1 leading to a 128-fold reduction in its MIC value. BA and BX demonstrated a 16-fold and an 8-fold reduction in the MIC value of CTX, respectively, when used for the treatment of MRSA ATCC 43300. The combination of CTX with any of the available commercial ß-lactamase inhibitors (clavulanic acid, sulbactam, tazobactam) did not produce an effect against MRSA ATCC 43300. Cytotoxicity was assessed using MTT assay on human umbilical vein endothelial cells (HUVECs) and the results showed no statistically significant toxic effect for the developed formulations. These novel findings suggest that PBA, a non-toxic and inexpensive compound, possesses structural similarities with β-lactam and may represent promising molecules to reverse resistance to CTX. This method can overcome the need to develop new antibiotics and render them more effective against MRSA.Graphical abstract

Sodium levulinate cellulose (SLC) was prepared as a new longer carbon chain analog for carboxymethyl cellulose (CMC) in 66–94% yield using the Williamson ether synthesis reaction between sodium hydroxide treated cellulose and brominated levulinic acid in aqueous iso-propanol medium under thermal and microwave conditions. Levulinate cellulose ether produced was characterized by FT-IR, TG–DTA, X-ray and proton NMR. The thermal reactions carried out at 90 °C for 3 and 24 h gave SLC products with degrees of substitutions of 0.48 and 0.86, respectively, whereas the microwave synthesis product showed a degree of substitution of 0.32 as determined by ASTM D1439-03 method used for CMC.Graphical abstract

AbstractA new amphiphilic six-armed A3B3-type miktoarm star polymer was synthesized starting from a triazidohydrin as the core. First, three hydrophobic arms of polycaprolactone were formed on the core through ring-opening polymerization (core-first method). Next, presynthesized PEG-based hydrophilic arms were attached to the previous structure using click chemistry (arm-first method). In the vicinity of the junction of the hydrophilic arms to the core, bio-reducible disulfide bonds were embedded. The prepared star polymer was characterized by elemental analysis and spectroscopic techniques (FT-IR and H-NMR). Using transmission electron microscopy (TEM) it was found that the amphiphilic macromolecules at concentrations higher than critical micelle concentration (CMC) formed spherical micelles with an average diameter below 100 nm. The CMC of the synthesized amphiphilic polymer in aqueous solution was determined by fluorometric method via examining the emission spectra of an organic probe. Thus, it was measured to be 1.76 × 10–3 mg/mL (3.90 × 10–7 M). In addition, dynamic light scattering measurements indicated that the spherical micelles had a mean hydrodynamic diameter (\(\overline{D }\)H) of ~ 70 nm and polydispersity index of 0.17.Graphical abstract

Propylene-ethylene (PPE) copolymer was added to high melt-strength polypropylene (HMS PP) for extrusion foaming. PPE postpones polypropylene (PP) crystalization and decreases the optimum foaming temperature. The blend maintains good melt strength and pronounced strain hardening(less than 30%) for a low melt mass flow rate (MFR) of PPE. The small phase separation of PPE (high ethylene content) and PP also favors cell nucleation during foaming. Thus, at lower foaming temperature, the small crystals may function as physical crosslinking, which can help to maintain melt strength and strain hardening behavior around the foaming window. The better cell nucleation and finer cells with higher expansion ratio (ER) in the foam sample were achieved. Combining the advantage of resin elasticity and better foam structure, better toughness was achieved with elongation at break as high as 150%, while maintaining the stiffness.Graphical abstract

The investigation of active biodegradable packaging was carried out in 2 parts. First, poly(lactic acid), PLA, was evaluated as a flexible packaging with poly(ethylene glycol), PEG incorporation at 5, 10, 20 and 30%wt. Moreover, the compatibility of PLA/PEG at low content of PEG 10%wt was improved by the chain extender (Joncryl ADR) at 1.0, 1.25 and 1.5 phr. These polymer blends were produced with reactive blending via twin screw extruder. Then, the blended films were made with cast film extrusion process. Films were undergone the characterization processes for the followings: chemical structures, thermal properties, rheological properties, mechanical properties and gas permeability. The addition of PEG had decreased glass transition temperature, whereas it raised the crystallization of PLA. The process ability and film strength were relatively poor at PEG 20 and 30%wt but demonstrated the high elongation at break. The process ability of PLA/PEG 10%wt was improved and elongation at break was greatly developed by the ADR addition of 1.25 phr. PLA/PEG10/ADR1.25-blended film could be used as flexible packaging with acceptable process ability and gas selectivity. Therefore, in the second part, PLA/PEG10/ADR1.25 (PPA) was developed by performing as the active packaging with the incorporation of the grape seed extract (GSE) 1, 2, 3 and 4 phr along with PLA-g-MA 3%wt. PPA with GSE 4 phr film was the only formula that had good compatibility and mechanical properties. Moreover, it exhibited excellent gas-selective film behavior which restricted oxygen gas permeation but allowed carbon dioxide gas to pass through permeation. In addition, PPA with GSE 4 phr film also revealed the effective antibacterial up to 99%. Finally, PPA with GSE 4 phr film had shown the best active packaging which could extend shelf life of straw mushrooms for at least 13 days.Graphical abstractPLA/PEG10/ADR1.25 (PPA) with GSE 4 phr film exhibited excellent gas selective film behavior which restricted oxygen gas permeation but allowed carbon dioxide gas to pass through permeation. In addition, PPA with GSE 4 phr film also revealed the effective antibacterial up to 99%. PPA with GSE 4 phr film had shown the best active packaging which could extend shelf life of straw mushrooms for at least 13 days

In this work we prepared poly(styrene-co-methacrylate) ionomers neutralized with three different monovalent cations and added these ionomers to heavy oil to determine how the ionomer affected asphaltenes dispersion in the heavy oil. First, it was found that ionomers neutralized with smaller-sized cations led to better dispersion of asphaltenes in heavy oil. Second, ionomers neutralized with smaller-sized cations were observed to slow the asphaltene aggregation process. Third, it was found that the concentration of the ionomer exhibiting the best asphaltene dispersibility depended on which cation neutralized the ionomer. The above results suggested that the strength of the interactions between the ions of the ionomer and the strength of the interactions between the cations of the ionomer and the functional groups of the asphaltenes were very important factors for the ionomers to act as effective asphaltene dispersants. The SAXS results also showed that the ionomer neutralized with smaller-sized cations induced asphaltene dispersion in heavy oil relatively well.Graphical Abstract The addition of poly(styrene-co-methacrylate) ionomers further improved the dispersion of asphaltenes in heavy oil as the size of the monovalent cation neutralizing the ionomer decreased. In addition, ionomers neutralized with smaller sized cations resulted in slower asphaltene aggregation. Also, the concentration of the ionomer in the heavy oil for the best asphaltene dispersion depended on the cation type of the ionomers. The above results indicated that the strength of the interactions between the ions of the ionomer and the strength of the interactions between the cations of the ionomer and the functional groups of the asphaltenes were very important factors for the ionomers to act as effective asphaltene dispersants.

In this study, the water absorption of poly(styrene-co-itaconate) PSITNa ionomers, having two ion pairs in an ionic repeat unit, was investigated. Plotting the water absorption data as a function of the ionic repeat unit content revealed that the PSITNa ionomer exhibited more water uptake than the poly(styrene-co-methacrylate) PSMANa ionomer, having one Na–carboxylate ion pair per ionic repeat unit. On the other hand, when the water absorption data were simply expressed as a function of the ion content, it was found that the PSMANa ionomer showed more water absorption than the PSITNa ionomer. These results and the SAXS results suggested that to increase the degree of water absorption of the ionomer, it would be better for the ion pairs of the ionomer to form aggregates with other ion pairs rather than to exist alone in the matrix. In addition, it was observed that the degree of water absorption of the ionomer gradually improved as the size of the cation used for neutralization of the ionomer increased. These results and morphological results indicated that when the strength of interaction between ion pairs was weakened, the number of ionic aggregates decreased, and, at the same time, the ionic aggregates readily absorbed water due to weak interaction between ion pairs in the aggregates.Graphical abstract The water absorption of poly(styrene-co-itaconate) PSITNa ionomers was investigated. It was found that to increase the degree of water absorption of the ionomer, it would be better for the ion pairs of the ionomer to form ionic aggregates with other ion pairs rather than to exist alone in the matrix. In addition, when the strength of interaction between ion pairs was weakened, the ionic aggregates readily absorbed water due to weak interaction between ion pairs in the ionic aggregates.

Hydrogel actuators have potential applications in many fields because of their multiple responsiveness to environmental stimuli. However, it is still very challenging to design a hydrogel actuator with simple preparation, fast response, and good mechanical properties. In this work, a facile and convenient method to obtain a fast responsive hydrogel actuator has been successfully developed by embedding uniform inorganic particles into Poly(N-isopropylacrylamide) hydrogel network to form an asymmetric structure. By controlling the types and contents of inorganic particles, a wide range of adjustable actuation property can be achieved. At the same time, the introduction of inorganic particles greatly increases the mechanical properties of hydrogels, which is also very important for actuation performance improvement of hydrogel actuators. The optimized hydrogel exhibits relatively fast bending deformation under thermal stimulation (60 ℃), with a bending velocity of about 13.0° s−1 within first 10 s and a bending amplitude of about 328.1° within 1 min. The hydrogel can be designed to be temperature-controlled claw actuators with programmable shapes, indicating its application prospects in encapsulating, grasping, and transporting objects in water environment.Graphical AbstractWe successfully designed and manufactured hybrid hydrogels with an asymmetric structure and improved mechanical property by adding inorganic particles to the PNIPAM hydrogel. The hybrid hydrogel with optimized SiO2 particles shows superior actuation properties due to bigger different in the swelling rates on both sides of hybrid hydrogels. The flexible and controllable deformation of the hydrogel actuator provides an inspiration for intelligent soft actuator in water environmental applications.

Highly refractive poly(phosphonate)s (BPOP), poly(thiophosphonate)s (BPTP), and poly(selenophosphonate)s (BPSP) with aromatic backbones were prepared by the polycondensation of phosphonic dichlorides and diols. The polymers have high thermal properties including high thermal properties (Td5% > 400 °C), glass transition temperature (Tg = 76 ~ 157 °C), and high optical properties such as transparency at 400 nm of over 80% for films of ca. 10 μm thickness, and a refractive index in the range of 1.633–1.675. In particular, BPSP exhibited a high refractive index (1.675) with low birefringence (0.0025) due to the heavy atom effect of selenium.Graphical abstractThis paper represent synthesis and characterization of highly refractive and transparent poly(phosphonate)s (BPOP), poly(thiophosphonate)s (BPTP), and poly(selenophosphonate)s (BPSP) with aromatic backbones in the polymer chains. The poly(phosphonate)s was prepared by the polycondensation of phosphonic dichlorides and diols. The polymers exhibited high thermal properties such as glass transition temperature (> 76 °C), and 5% weight loss temperature at > 393 °C under nitrogen. The polymers also showed good optical properties, including high optical transparency in the visible region, a low birefringence of 0.0099–0.0026, and high refractive indices of 1.6333–1.6757 at 637 nm.

Polymerization of styrene with tributylborane in the presence of various p-quinones (2,3-dimethyl-1,4-benzoquinone, 1,4-naphthoquinone, menadione, duroquinone, 2,5-di-tert-butyl-1,4-benzoquinone) has been investigated. It was found that in spite of dual nature of p-quinone and the presence of tributylborane in the initial mixture, the semi-quinone macroradical is capable to “chain regeneration”. Neither solvent introduction nor use of a more reactive triethylborane affects this process. The insensitivity of this reaction to external conditions may be caused by the cell effect. For some p-quinones in the presence of tributylborane, the realization of reversible-deactivation radical polymerization is observed. Mechanism of the chain termination reactions was established by the MALDI-TOF technique. It consists of reversible inhibition causing the formation of active macromolecules as well as irreversible inhibition causing the formation of “dead” macromolecules. The ratio of these directions depends on the relative reactivity of p-quinone (kz/kp). The higher is kz/kp, the lower is the probability of irreversible inhibition. Polymers obtained in the presence of the tributylborane/p-quinone system can re-initiate polymerization. Post-polymers with distinct molecular weight characteristics (Đ = 1.12 – 1.19) were obtained during this synthesis. Only polystyrene macro-radicals are formed during polymerization re-initiation. This fact has been proven by ESR spectroscopy. The macroinitiator polymers isolated at the initial conversions have the same reactivity regardless of the p-quinone nature. The linear dependence of Mn with conversion, the polydispersity lessening, and the constant concentration of macro-radicals indicate realization of reversible-deactivation radical polymerization.Graphical abstract

The immunological effects according to the difference in the degree of deacetylation (DD) and molecular weight (MW) of chitosan purified from Hermetia illucens larvae were investigated. The DD of purified high molecular weight chitosan (Hi-CTSN) from H. illucens larvae was found to be 87.2%. According to the substrate specificity of the enzyme, Hi-CTSN was treated with chitosanase and chitinase to prepare chitooligosaccharides (CTS) named CTS2 and CTS3, respectively. For comparison of relative activity, CTS1 obtained by treating crab shell-derived HMWC1 with chitosanase was used as a control. Matrix-assisted laser desorption/ionization (MALDI-TOF) mass spectrometry was subjected to determine the sugar components constituting CTS1, CTS2, and CTS3, respectively. By examining the biological activity of CTS and the immuno-stimulatory activity of CTS according to MW and DD, the expression of many inflammatory cytokines related to the peripheral immune system in macrophage RAW 264.7 cells was confirmed. As a result, all CTS showed similar effects on the expression of tumor necrosis factor-α (TNF-α) in all concentration ranges used. Among them, CTS1 was verified to have a significant effect on the secretion of inflammatory cytokines, such as interleukin-6 (IL-6) and interleukin-1β (IL-1β), at a high concentration of 250–500 μg/mL. However, CTS3 showed significantly higher expression than CTS1 and CTS2 at low concentrations ranging from 50 to 100 μg/mL. However, there was no significant difference in antioxidant activity against FRAP, ABTS, and DPPH in all CTS. Our results suggest that the presence or absence of the acetyl group of CTS in response to immune stimulation showed a very significant difference, but had a less substantial association with antioxidant activity. Therefore, our data suggested that the difference in DD had a more substantial effect on the immuno-stimulatory activity than the MW of CTS. Graphical abstract

Recently, a significant number of works have appeared devoted to the creation of materials with controlled delivery of drugs. The most promising polymers for these purposes are polysaccharides, in particular chitosan. Unfortunately, film materials obtained from a solution based on chitosan in salt form are soluble in water. In this regard, the purpose of this work was to consider the possibility of modifying the chitosan film materials. Sodium sulfate, phosphoric, succinic, and oxalic acids were chosen as polymer material modifiers. It was shown that the introduction of sodium sulfate, phosphoric, and oxalic acids leads to the loss of solubility of the film materials, changes of the shape of the sorption curve and decrease in the values of the diffusion coefficients of water vapor occurs. The introduction of a weak dibasic succinic acid as a modifier does not lead to a change in the process of sorption regime. The similar regularities are founded in the study of the process of drug release from the polymer material. Thus, fundamentally possible ways of regulating the transport properties of the chitosan film material with respect to the yield of drugs have been found, which consist in the modification of chitosan with anions of strong polybasic acids. Graphical abstractMicrograph of the surface of a chitosan film in contact with air and a substrate

Biomass-derived isosorbide (ISB) is a promising alternative to petroleum-based monomers in industrial plastics. In this study, ISB-based thermoplastic polyurethanes (ISB-TPUs) were prepared using ISB as a biomass chain extender, and the effects of the preparation route on the structural and physical properties of the resultant polymers were investigated. Prepolymer methods were more suitable for obtaining the desired molecular weights (MWs) and physical properties of ISB-TPUs than the one-shot method. The presence of the solvent and catalyst in the prepolymer step had significant effects on the structural and physical properties of the resultant polymer. Among several prepolymer conditions, the solvent- and catalyst-free methods were the most suitable for preparing commercial-level ISB-TPUs, with number- and weight-average MWs (Mn and Mw) of 32,881 and 90,929 g mol−1, respectively, and a tensile modulus (E) and ultimate tensile strength (UTS) of 12.0 and 40.2 MPa, respectively. In comparison, the presence of a catalyst in the prepolymer step resulted in lower MWs and mechanical properties (81,033 g mol−1 and 18.3 MPa of Mw and UTS, respectively). The co-existence of the catalyst/solvent led to a further decline in the properties of ISB-TPUs (26,506 and 10.0 MPa of Mw and UTS, respectively). ISB-TPU prepared via the solvent- and catalyst-free methods exhibited remarkable elastic recovery when subjected to up to 1000% strain in mechanical cycling tests. Rheological characterization confirmed the thermo-reversible phase change (thermoplasticity) of the polymer.Graphical abstract

In this work, PDMS films are treated with varying fluence of hydrogen ion beams (6 × 1017, 9 × 1017, and 12 × 1017 ions/cm2) for used in storage energy devices. XRD and FTIR were used to analyze the PDMS films. Furthermore, the SEM is employed to study the morphological alterations in treated PDMS films. Both XRD and FTIR result indicated that PDMS is chemically interacting after ion treatment. In addition, the dielectric parameters of PDMS films are measured using an LCR device in the frequencies 102–106 Hz. After PDMS exposed to 12 × 1017 ions/cm2, the dielectric constant of the PDMS increased from 23.4 to 44.8, and energy density increased from 1.01 × 10–4 to 1.92 × 10–4 J/m3, while the conductivity increased from 0.29 × 10–7 to 4.3 × 10–7 S/cm. Moreover, the real M′ decreased from 0.198 for PDMS to 0.165 for 6 × 1017 ions/cm2 and to 0.052 at 12 × 1017 ions/cm2, while the imaginary M″ is decreased from 0.205 to 0.155 for 6 × 1017 ions/cm2, and to 0.069 for 12 × 1017 ions/cm2. The studies indicated that the structure as well as electrical characteristics of the treated PDMS had been improved, which allowing being used these substances in different electronic instrumentations.Graphical abstract

The salinity gradient between seawater and river water is a type of Gibbs energy that can be converted into electrical energy by an ion-exchange membrane. Although the salinity gradient between two aqueous solutions can be adjusted in a laboratory to improve the energy-harvesting performance, the salinity gradient in natural resources is rather constant, restricting the prospects of membrane-mediated power generation. To address this issue, we demonstrate the local enhancement of the salinity gradient through hydrogel-functionalized anodic aluminum oxide (AAO) membranes. In the composite structure, the surface-modified AAO membrane attracts the mobile counter ions from the hydrogels to increase the local concentration of mobile ions inside the nanopores of AAO membrane. Owing to the local concentration enhancement, the hydrogel-functionalized AAO membranes could extract electrical energy with improved efficiency, which could power small electronic devices.Graphical Abstract Hydrogel-functionalized anodic aluminum oxide (AAO) membranes have been prepared, which could locally enhance a concentration gradient in the salinity-gradient cells to extract electric energy with improved efficiency.

With the recent advancement in emerging biomedical engineering fields, such as tissue engineering, regenerative medicine, and wearable medical devices, there is a growing need to develop adhesives that can function not only as tissue sealants for surgery and wound closure, but also attach various biomaterials and devices. These “bioadhesives” should allow refined control of cohesive and adhesive properties, while significantly improving the biocompatibility and biodegradability. For this reason, bioadhesives are being developed using a wide range of natural biopolymers with proven biocompatibility that can also impart multifunctionality either using their innate properties and/or obtained via various chemical modifications. In this review, state-of-the-art bioadhesives made from multifunctional biopolymers are introduced. Graphical abstractNatural biopolymers are increasingly utilized to develop adhesives for biomedical applications, including wound healing and biomedical devices, for their favorable physicomechanical properties as well as their proven biocompatibility. Furthermore, various modification strategies are often employed to impart multifunctionality. In this review, recent development and notable examples of bioadhesives based on multifunctional biopolymers are highlighted.

Chemotherapy is the main strategy for inhibiting the tumor growth. However, during the therapy, the side effect of anti-cancer drug will injure normal cells. For reducing the toxic of the free drug, stimuli responsive nanoparticles (NPs) have been prepared base on the pathological acidic environment around tumor for safe and efficient anti-tumor applications. In this study, we fabricated the phenylboronic acid (PBA) modified monomethoxy polyethylene glycol (MEPG) for encapsulating doxorubicin (DOX NPs). In the drug delivery system (DDS), the pH-responsive boric ester could be stable during drug delivery, and enhance DOX rapidly release in tumor lesion under the acidic stimuli. In vitro studies further demonstrated that DOX NPs could efficiently endocytose by tumor cells, and exhibit the similar anti-tumor activity as the free DOX resulting from the pH-responsive drug release profiles under tumor acidic stimuli. In summary, DOX NPs could be a feasible candidate to improve the safe and efficient DOX delivery for improving the potential anti-tumor applications.Graphical abstract

The success of tissue engineering scaffolds for wound healing relies on balanced physicochemical properties and the addition of small molecules. These two require an in-depth understanding of the interactions between the different components of the scaffolds for favorable and synergistic actions. Thus, the choice of polymeric blends is crucial to tune the properties of the resulting scaffolds. Miscibility of the polymer blends can be used to assess polymer–polymer interactions for effective scaffold engineering and cell–material interactions. The focus of this study was to apply machine learning (ML) methods to classify and predict the miscibility of polymer blends, namely poly(hydroxybutyrate-co-valerate)/fucoidan (PHBV/FUC), polyhydroxybutyrate/kappa-carrageenan (PHB/KCG), and cellulose acetate/polyamide (CA/PA). Physicochemical parameters assessed through Fourier transform infrared spectroscopy (FTIR), thermal analysis, and mechanical properties were used as input data. Depending on blend film compositions, the polymers were either partially miscible or completely immiscible. Six supervised classification algorithms were trained on the data with Scikit-learn. The random forest classifier outperformed the other algorithms with the optimal performance metrics. A simple multiple linear regression model was applied to polymer–drug interaction data. Preliminary results indicated that regression models could be correlated with ultraviolet (UV) absorbance of polymer–drug solutions.Graphical abstract

Solution-processable techniques, including spin-coating, roll-to-roll printing, and ink-jet printing, are suitable for large-scale manufacturing and flexible displays owing to their cost-effective and simple fabrication. These techniques are widely used in the fabrication of perovskite light-emitting diodes (PeLEDs) and organic light-emitting diodes (OLEDs). However, the energy level modulation between different functional layers, thickness control of the deposited layer, and interlayer mixing between the deposited and subsequent layers may affect the LED performance due to the poor solvent resistance of the deposited layer. Herein, we designed a novel poly[4,4'-(2-(4-((4-hexylphenyl)(phenyl)amino)phenyl)-9H-fluorene-9,9-diyl)bis(N,N-bis(4-butylphenyl)aniline)] (PFTPA-biTPA) as a hole transport layer (HTL) to modulate the hole injection. Subsequently, we introduced the bis(4-azido-2,3,5,6-tetrafluorobenzoate) (FPA) as a photo-crosslinker into the PFTPA-biTPA to prepare the photo-crosslinked HTL for both PeLED and OLED that inhibit attack from the processing solution and suppress the interlayer mixing between the deposited and subsequent layers. Both PeLEDs and OLEDs with photo-crosslinked PFTPA-biTPA exhibited maximum luminance of 175 and 4260 cd/m2 and maximum external quantum efficiency (EQE) of 4.16 and 10.86%, respectively, thus indicating superior properties to those without and with PFTPA-biTPA as the HTLs. Moreover, the photo-crosslinked PFTPA-biTPA showed significantly improved device stability compared to the reference devices having non-photo-crosslinked HTLs in PeLEDs.Graphical abstractSchematic illustration of crosslinked hole transport polymer with enhanced hole transport and solvent resistance