Depolymerized Chitosan-g-[Poly(MMA-co-HEMA-cl-EGDMA)] Based Nanogels for Controlled Local Release of Bupivacaine.

This study is designed to formulate and characterize chitosan-based nanogels that provide the controlled delivery of anesthetic drugs, such as bupivacaine (BPV), for effective postoperative pain management over prolonged periods of time. Drug carriers of chitosan/poly (MMA-co-HEMA-cl-EGDMA) (CsPMH) nanogels were prepared by varying the composition of comonomers such as MMA, HEMA, and redox initiator CAN. The nanogels were then characterized using FTIR, TGA, SEM, and TEM. The CsPMH nanogels showed greater encapsulation efficiencies from 43.20-91.77%. Computational studies were also conducted to evaluate the interaction between the drug and CsPMH nanoparticles. Finally, BPV-loaded nanoparticles were used to examine their in vitro release behavior. At pH 7.4, all the drug carriers displayed the "n" value around 0.7, thus the BPV release follows anomalous diffusion. Drug carrier 7 demonstrated a steady and sustained release of BPV for approximately 24 h and released about 91% of BPV, following the K-P mechanism of drug release. On the other hand, drug carrier 6 exhibited controlled release for approximately 12 h and released only 62% of BPV.

Effects of Recycled Polymer on Melt Viscosity and Crystallization Temperature of Polyester Elastomer Blends.

As the world is paying attention to the seriousness of environmental pollution, the need for a resource circulation economy is emerging due to the development of eco-friendly industrial groups. In particular, the recycling of thermoplastic elastomers without cross-link has been highlighted in the plastics field, which has rapidly developed the industry. Growing interests have been directed towards the advancement of thermoplastic polyether-ester elastomer (TPEE) as a material suitable for the circular economy owing to its remarkable recyclability, both in terms of mechanical and chemical processes. Due to its excellent processability, simple mechanical recycling is easy, which is a driving force towards achieving price competitiveness in the process. In molding TPEE resin, it is essential to check the thermal properties of the resin itself because the thermal properties, including the melting and crystallization temperatures of the resin, depend on the design of the polymer. In this study, the thermal and mechanical performances of TPEE blends were evaluated by manufacturing compounds by changing the amount of recycled resin and additives. When the recycled resin was added, the melt flow index (MFI) changed rapidly as the temperature of the melt flow index measurement increased. Rapid changes in MFI make the fiber spinning process uncontrollable and must be controlled by optimizing the addition of compatibilizers. Based on the thermal property results, compatibilizers such as Lotader and Elvaloy series exhibited minimal change in glass transition temperature, even with greater amounts added. This makes them well-suited as compatibilizers for fiber spinning.

Polydopamine/polypyrrole-modified graphite felt enhances biocompatibility for electroactive bacteria and power density of microbial fuel cell.

The interactions between the microbes and the surface of an anode play an important role in capturing the respiratory electrons from bacteria in a microbial fuel cell (MFC). The chemical and electrochemical characteristics of the carbon material affect biofilm growth and direct electron transfer in MFCs. This study examined the electrodeposition of polydopamine (PDA) and polypyrrole (PPY) on graphite felt electrode (GF). The MFC with the modified PDA/PPY-GF reached 920 mW/m2, which was 1.5, 1.17, and 1.18 times higher than those of the GF, PDA-GF, and PPY-GF, respectively. PDA has superior hydrophilicity and adhesive force biofilm formation, while PPY provides electrochemically active sites for microbial electron transfer. Raman spectroscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area measurements, and contact angle analysis revealed the enhanced physicochemical properties of the carbon electrode. These results show that co-doped PDA/PPY provides a strategy for electroactive biofilm development and improves the bioelectrochemical performance in realistic MFC reactors.

Dual (pH- and ROS-) Responsive Antibacterial MXene-Based Nanocarrier for Drug Delivery.

In this study, a novel MXene (Ti3C2Tx)-based nanocarrier was developed for drug delivery. MXene nanosheets were functionalized with 3, 3'-diselanediyldipropionic acid (DSeDPA), followed by grafting doxorubicin (DOX) as a model drug to the surface of functionalized MXene nanosheets (MXene-Se-DOX). The nanosheets were characterized using scanning electron microscopy, atomic force microscopy (AFM), transmission electron microscopy, energy-dispersive X-ray spectroscopy (EDX), nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and zeta potential techniques. The drug-loading capacity (17.95%) and encapsulation efficiency (41.66%) were determined using ultraviolet-visible spectroscopy. The lateral size and thickness of the MXene nanosheets measured using AFM were 200 nm and 1.5 nm, respectively. The drug release behavior of the MXene-Se-DOX nanosheets was evaluated under different medium conditions, and the nanosheets demonstrated outstanding dual (reactive oxygen species (ROS)- and pH-) responsive properties. Furthermore, the MXene-Se-DOX nanosheets exhibited excellent antibacterial activity against both Gram-negative E. coli and Gram-positive B. subtilis.

ROS- and pH-Responsive Polydopamine Functionalized Ti3C2Tx MXene-Based Nanoparticles as Drug Delivery Nanocarriers with High Antibacterial Activity.

Premature drug release and poor controllability is a challenge in the practical application of tumor therapy, which may lead to poor chemotherapy efficacy and severe adverse effects. In this study, a reactive oxygen species (ROS)-cleavable nanoparticle system (MXene-TK-DOX@PDA) was designed for effective chemotherapy drug delivery and antibacterial applications. Doxorubicin (DOX) was conjugated to the surface of (3-aminopropyl)triethoxysilane (APTES)-functionalized MXene via an ROS-cleavable diacetoxyl thioketal (TK) linkage. Subsequently, the surfaces of the MXene nanosheets were coated with pH-responsive polydopamine (PDA) as a gatekeeper. PDA endowed the MXene-TK-DOX@PDA nanoparticles with superior biocompatibility and stability. The MXene-TK-DOX@PDA nanoparticles had an ultrathin planar structure and a small lateral size of approximately 180 nm. The as-synthesized nanoparticles demonstrated outstanding photothermal conversion efficiency, superior photothermal stability, and a remarkable extinction coefficient (23.3 L g-1 cm-1 at 808 nm). DOX exhibited both efficient ROS-responsive and pH-responsive release performance from MXene-TK-DOX@PDA nanoparticles due to the cleavage of the thioketal linker. In addition, MXene-TK-DOX@PDA nanoparticles displayed high antibacterial activity against both Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis (B. subtilis) within 5 h. Taken together, we hope that MXene-TK-DOX@PDA nanoparticles will enrich the drug delivery system and significantly expand their applications in the biomedical field.

Interfacial Properties and Melt Processability of Cellulose Acetate Propionate Composites by Melt Blending of Biofillers.

A series of eco-friendly biocomposites with improved mechanical properties and interfacial interaction were prepared by melt-mixing natural fibers using a cellulose acetate derivative as a polymer matrix and used to evaluate their mechanical, thermal, and morphological properties. The natural fiber used as a biofiller was pre-surface-treated by a refining process using alkali and natural enzymes to improve compatibility and increase interfacial bonding with biopolymer substrate. To increase the processability of the cellulose material, the raw material was plasticized and the composition prepared in the form of pellets in a twin-screw extruder by mixing with an additive before being molded through an injection process. For each composition, the interfacial bonding force between different materials was confirmed through morphology analysis and evaluation of mechanical and thermal properties. When biofillers and a viscosity modifier were used at the same time, the fabricated biocomposites had controllable crystallinity, stiffness, and elasticity and showed improved mechanical strength, such as tensile strength and flexural strength. These results indicated that interfacial properties could be increased through interfacial interactions between two different components due to appropriate surface treatment. In addition, it was confirmed that a composition having interfacial interaction, not a simple mixture, could be prepared by lowering both glass transition and melting temperature. The lowering of glass transition temperature increased the elasticity of the biocomposites, which have the potential advantage of easier melt processing when applied to various injection parts.

Biodegradable PCL-b-PLA Microspheres with Nanopores Prepared via RAFT Polymerization and UV Photodegradation of Poly(Methyl Vinyl Ketone) Blocks.

Biodegradable triblock copolymers based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were synthesized via ring-opening polymerization of L-lactide followed by reversible addition-fragmentation chain-transfer (RAFT) polymerization of poly(methyl vinyl ketone) (PMVK) as a photodegradable block, and characterized by FT-IR and 1H NMR spectroscopy for structural analyses, and by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) for their thermal properties. Porous, biodegradable PCL-b-PLA microspheres were fabricated via the oil/water (O/W) emulsion evaporation method, followed by photodegradation of PMVK blocks by UV irradiation. The macro-chain transfer agent (CTA) synthesized by reacting a carboxylic-acid-terminated CTA-S-1-dodecyl-S'-(a,a'-dimethyl-a''-acetic acid)trithiocarbonate (DDMAT)-with a hydroxyl-terminated PCL-b-PLA block copolymer was used to synthesize well-defined triblock copolymers with methyl vinyl ketone via RAFT polymerization with controlled molecular weights and narrow polydispersity. Gel permeation chromatography traces indicated that the molecular weight of the triblock copolymer decreased with UV irradiation time because of the photodegradation of the PMVK blocks. The morphology of the microspheres before and after UV irradiation was investigated using SEM and videos of three-dimensional confocal laser microscopy, showing a change in their surface texture from smooth to rough, with high porosity owing to the photodegradation of the PMVK blocks to become porous templates.

Fabrication and Biological Activities of Plasmid DNA Gene Carrier Nanoparticles Based on Biodegradable l-Tyrosine Polyurethane.

Gene therapy is a suitable alternative to chemotherapy due to the complications of drug resistance and toxicity of drugs, and is also known to reduce the occurrence of cellular mutation through the use of gene carriers. In this study, gene carrier nanoparticles with minimal toxicity and high transfection efficiency were fabricated from a biocompatible and biodegradable polymer, l-tyrosine polyurethane (LTU), which was polymerized from presynthesized desaminotyrosyl tyrosine hexyl ester (DTH) and polyethylene glycol (PEG), by using double emulsion and solvent evaporation techniques, resulting in the formation of porous nanoparticles, and then used to evaluate their potential biological activities through molecular controlled release and transfection studies. To assess cellular uptake and transfection efficiency, two model drugs, fluorescently labeled bovine serum albumin (FITC-BSA) and plasmid DNA-linear polyethylenimine (LPEI) complex, were successfully encapsulated in nanoparticles, and their transfection properties and cytotoxicities were evaluated in LX2 as a normal cell and in HepG2 and MCF7 as cancer cells. The morphology and average diameter of the LTU nanoparticles were confirmed using light microscopy, transmission electron microscopy, and dynamic light scattering, while confocal microscopy was used to validate the cellular uptake of FITC-BSA-encapsulated LTU nanoparticles. Moreover, the successful cellular uptake of LTU nanoparticles encapsulated with pDNA-LPEI and the high transfection efficiency, confirmed by gel electrophoresis and X-gal assay transfection, indicated that LTU nanoparticles had excellent cell adsorption ability, facilitated gene encapsulation, and showed the sustained release tendency of genes through transfection experiments, with an optimal concentration ratio of pDNA and LPEI of 1:10. All the above characteristics are ideal for gene carriers designed to transport and release drugs into the cytoplasm, thus facilitating effective gene therapy.

Synthesis of size-controlled and highly monodispersed silica nanoparticles using a short alkyl-chain fluorinated surfactant.

Highly monodispersed silica nanoparticles (SiNPs) were synthesised using a fluorinated surfactant, HOCH2CH(CF3)CO2H, and its efficiency was compared with efficiencies of five other surfactants. The size of the SiNPs (∼50-200 nm) was controlled by controlling the surfactant amount. The short alkyl-chain fluoro surfactant was found to be more efficient at producing monodispersed SiNPs than its long alkyl-chain fluoro or non-fluorinated surfactant counterparts.

Synthesis and Characterization of Polyfumarateurethane Nanoparticles for Sustained Release of Bupivacaine.

Biodegradable polyfumarateurethane (PFU) for use as a bupivacaine delivery vehicle, synthesized using di-(2-hydroxypropyl fumarate) (DHPF), polyethylene glycol (PEG) and 1,6-hexamethylene diisocyanate (HMDI), was designed to be degradable through the hydrolysis and enzymatic degradation of the ester bonds in its polymer backbone. Using a water-in-oil-in-water double emulsion techniques, nanoparticles encapsulating water or fluorescein isothiocyanate (FITC) were fabricated to avoid the immune system owing to the presence of PEG on their surface. The morphologies of these nanoparticles were characterized by DLS, TEM, FE-SEM, and fluorescent microscopies. The present study explored the encapsulation, loading efficiency and in vitro drug release of bupivacaine encapsulated with biodegradable PFU nanoparticles for the treatment of local anesthesia. Various concentrations of bupivacaine were encapsulated into nanoparticles and their encapsulation efficiencies and drug loading were investigated. Encapsulation efficiency was highest when 2.5% bupivacaine was encapsulated. Drug release behavior from the bupivacaine-loaded PFU nanoparticles followed a sustained release profile.

Fabrication and Electrochemical Characterization of Polyaniline/Titanium Oxide Nanoweb Composite Electrode for Supercapacitor Application.

In this study, polyaniline/titanium oxide (PANi-TiO2) nanoweb composite was fabricated through electrochemical deposition and electrospinning techniques, and the composite was further utilized as an electrode for a supercapacitor. The PANi-TiO2 composite film showed three-dimensional hierarchical micro/nano architecture. The film was deposited on the current collector without the use of any binders. The morphology of the PANi-TiO2 composite film was confirmed by the use of field emission scanning electron microscopy (FE-SEM) analysis that polyaniline was grown in the form of nanorods with a diameter of 100 nm-200 nm on a TiO2 nanoweb. The chemical composition and quantitative analysis were determined by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The electrochemical properties were analyzed by cyclic voltammetry (CV), chronopotentiometry, and electrochemical impedance spectroscopy (EIS). The result of electrochemical tests indicated that TiO2-PANi electrode displayed a high specific capacitance of 306.5 Fg(-1) at the scan rate of 20 mVs(-1), with the capacitance retention ratio being 103% after 500 cycles at the scan rate of 50 mVs(-1).

MicroRNA-378 limits activation of hepatic stellate cells and liver fibrosis by suppressing Gli3 expression.

Hedgehog (Hh) signalling regulates hepatic fibrogenesis. MicroRNAs (miRNAs) mediate various cellular processes; however, their role in liver fibrosis is unclear. Here we investigate regulation of miRNAs in chronically damaged fibrotic liver. MiRNA profiling shows that expression of miR-378 family members (miR-378a-3p, miR-378b and miR-378d) declines in carbon tetrachloride (CCl4)-treated compared with corn-oil-treated mice. Overexpression of miR-378a-3p, directly targeting Gli3 in activated hepatic stellate cells (HSCs), reduces expression of Gli3 and profibrotic genes but induces gfap, the inactivation marker of HSCs, in CCl4-treated liver. Smo blocks transcriptional expression of miR-378a-3p by activating the p65 subunit of nuclear factor-κB (NF-κB). The hepatic level of miR-378a-3p is inversely correlated with the expression of Gli3 in tumour and non-tumour tissues in human hepatocellular carcinoma. Our results demonstrate that miR-378a-3p suppresses activation of HSCs by targeting Gli3 and its expression is regulated by Smo-dependent NF-κB signalling, suggesting miR-378a-3p has therapeutic potential for liver fibrosis.

Antitumor and antiangiogenic active dendrimer/5-fluorouracil conjugates.

Antitumor and antiangiogenic active dendritic compounds conjugated with 5-fluorouracil (5-FU) were synthesized and characterized. First, the core structure based on ascorbic acid and dicarboxylic acid was synthesized, amidated with ethylenediamine. For the synthesis of higher generated dendrimer, it was reacted further with methyl acrylate to increase molecular weight through Michael addition reaction, followed by the continuous repeating amidation reaction, finally, used to synthesize covalently bound dendrimer/5-FU conjugates. The in vitro cytotoxicities of the conjugates was evaluated with mouse mammary carcinoma, mouse leukemia, and human histiocytic lymphoma as cancer cell lines and mouse liver cells as a normal cell line, and showed lower values than 5-FU. The in vivo antitumor activities of the conjugates against mice bearing sarcoma 180 tumor cell line were better than 5-FU. Especially, Second generated dendrimer (G-2)/5-FU conjugates showed excellent in vivo antitumor as well as antiangiogenic activities evaluated by the embryo chorioallantoic membrane assay due to slow hydrolysis rate and the amount of 5-FU released.

Synthesis of organic-inorganic hybrid sols with nano silica particles and organoalkoxysilanes for transparent and high-thermal-resistance coating films using sol-gel reaction.

Organic-inorganic hybrid sols were synthesized from nano silica particles dispersed in water and from organoalkoxysilanes, using the sol-gel reaction. This work focuses on the effects of the three multifunctional organoalkoxysilanes dimethyldimethoxysilane (DMDMS), methyltrimethoxysilane (MTMS), and tetramethoxysilane (TMOS) to form a transparent and high-thermal-resistance coating film. The stability of the hybrid sol was evaluated as a function of the reaction time for 10 d through the variation of the viscosity. The viscosity of the silica/DMDMS and silica/MTMS sol was slightly increased for 10 d. The multifunctional organoalkoxysilanes formed dense silica networks through hydrolysis and condensation reaction, which enhanced the thermal resistance of the coating films. No thermal degradation of the silica/DMDMS sample occurred up to 600 degrees C, and none of the silica/MTMS and silica/TMOS samples occurred either up to 700 degrees C. The organic-inorganic hybrid sols were coated on the glass substrate using a spin-coating procedure. The organic-inorganic hybrid sols formed flat coating films without cracks. The transmittance of the hybrid sol coating films using MTMS and DMDMS was shown to be over 90%. The transmittance of the silica/TMOS sol coating film reacted for 10 d abruptly decreased due to faster gelation. The silica/DMDMS and silica/MTMS hybrid sols formed smooth coating films while the surface roughness of the silica/TMOS coating film markedly increased when the hybrid sol reacted for 10 d. The increase of the surface roughness of the silica/TMOS coating film can be attributed to the degradation of the stability of the hybrid sol and to the loss of transmittance of the coating film. It was confirmed in this study that the use of organic-inorganic hybrid sol can yield transparent and high-thermal-resistance coating films.

Synthesis and evaluation of novel bifunctional oligomer-based composites for dental applications.

Five novel bifunctional oligomers containing both carboxylic acid and methacrylate groups are synthesized, characterized, and used to formulate compomers by mixing with strontium fluoroaluminosilicate glass powder at a filler level of 75% (by weight). Compressive strength (CS) of the cements and viscosity of the resin liquids are used as screening tools to find the optimal formulation. Diametral tensile (DTS) and flexural strengths (FS) are also determined. Results show that the oligomers derivatized with glycerol dimethacrylate exhibit higher CS than those with 2-hydroxyethyl methacrylate. The CS increases with increasing diluent content, filler level, and light-exposure time. During aging, the cement shows an increase of strength over 24 h and then remains unaltered for up to 3 months. The experimental compomer is 45 and 69% higher in CS, 35 and 174% higher in DTS, and 39 and 170% higher in FS, respectively, as compared to Dyract and Fuji II LC.

Synthesis of amino acid-based polymers via atom transfer radical polymerization in aqueous media at ambient temperature.

Well-defined acryloyl beta-alanine (ABA) polymers were synthesized directly via atom transfer radical polymerization (ATRP) under near physiological conditions using various water soluble initiators with high yield and narrow molecular weight distributions.

Synthesis and evaluation of HEMA-free glass-ionomer cements for dental applications.

OBJECTIVE: The objective of this study was to synthesize and characterize amino acid acrylate and methacrylate derivatives, use them to formulate light-cured glass-ionomer cements (LCGICs), and evaluate their mechanical strengths. MATERIALS AND METHODS: Acrylate and methacrylate derivatives of six amino acids were synthesized and characterized using FT-IR and 1HNMR spectroscopy. The LCGICs were formulated using a newly synthesized polymer having pendant methacrylate groups (in other words, a methacryloyl derived polymer or MDP), amino acid derivatives, water, and Fuji II LC glass. Compressive strength of the cements and viscosities of the resin liquids were used as screening tools in order to determine the optimal formulation. The specimens were conditioned in distilled water at 37 degrees C for 24 h prior to testing. RESULTS: The measured compressive strengths (MPa) of the cements were found to depend on the amino acid derivative used: acryloyl aspartic acid (268.5) > methacryloyl beta-alanine (259.1) = methacryloyl glutamic acid (254.5) = acryloyl beta-alanine (251.9) > acryloyl glutamic acid (238.8) > methacryloyl aspartic acid (210.9). Methacryloyl beta-alanine (MBA) was selected for further formulations due to its relatively low solution viscosity and high compressive strength. Effects of MDP content and power/liquid (P/L) ratio were significant. The formulation with a liquid composition of 50/25/25 (MDP/MBA/water) and P/L ratio of 2.7/1 was found to give optimal properties and handling of all the formulations studied. CONCLUSIONS: A novel HEMA-free LCGIC system based on amino acid derivatives has been developed. This system may eliminate potential cytotoxicity in current LCGICs caused by leached 2-hydroxyethyl methacrylate (HEMA). The optimal MBA-modified cements were 20% higher in compressive strength, 70% higher in diametral tensile strength (DTS) and 93% higher in flexure strength (FS), as compared to Fuji II LC cement.

An amino acid-modified and non-HEMA containing glass-ionomer cement.

It is known that unreacted 2-hydroxyethyl methacrylate (HEMA) in current resin modified glass ionomer cements (RMGICs) shows potential cytotoxicity to pulp and surrounding tissues. Elimination of HEMA could make RMGICs more attractive for dental applications. In this research, novel six acrylate and methacrylate derivatives of amino acids were synthesized, characterized and used for replace HEMA in RMGICs. The experimental RMGICs were formulated with vinyl-containing polymer, amino acid derivative, water, and commercial Fuji II LC glass. Among all the derivatives, methacryloyl beta-alanine (MBA) was selected for further formulations due to its relatively low solution viscosity and high CS. Effects of polymer content and powder/liquid, P/L, ratio were significant. The formulation with liquid composition of 50/25/25 (polymer/MBA/water) and P/L ratio of 2.7/1 was found the optimal. It appears that this novel non-HEMA-containing RMGIC system based on amino acid derivatives will be a better dental restorative because it demonstrated improved mechanical strengths and may eliminate potential cytotoxicity in current RMGICs caused by leached HEMA. The optimal MBA-modified GIC were 20% higher in CS, 70% higher in DTS and 93% higher in FS, compared to Fuji II LC.

A hybrid zinc-calcium-silicate polyalkenoate bone cement.

A novel bone cement composed of sintered zinc-calcium-silicate phosphate and hybrid polyalkenoates has been developed. Synthesis and formulation of glass fillers, monomers and polymers as well as formulation of the cement were described. The effects of sintering, polymer content, glass powder/polymer liquid (P/L) ratio and comonomer on compressive strength (CS) and curing time (CT) were investigated. The effects of P/L ratio and comonomers on shrinkage as well as exotherm were also studied. Results show that the experimental cement was 61% higher in CS, 10% lower in diametral tensile strength, 35% lower in flexural strength, 62% less in exotherm, and 68% less in shrinkage, compared to conventional polymethylmethacrylate cement. With increasing polymer content and P/L ratio in the cement formulation CS of the cement increased but CT decreased. Curing time, shrinkage and exotherm of the cement decreased with increasing P/L ratio. It appears that this novel cement may be a potential candidate for orthopedic restoration if its biological performance is good and formulation is optimized.