14-3-3σ plays an important role in controlling tumor metabolic reprogramming and cancer cell growth. However, its function is often compromised in many cancers due to its downregulation. Previous studies found that homodimerization of 14-3-3σ is critical for its activity. However, to date, it is not known if stabilization of 14-3-3σ homodimers can improve its activity or prevent its degradation. In our previous work, we have showed that GCP-Lys-OMe is a potential 14-3-3σ homodimer stabilizer. However, its stabilizing effect was not experimentally validated. Therefore, in this study, we have attempted to predict few potential peptides that can stabilize the dimeric form of 14-3-3σ using similar in silico techniques as described previously for GCP-Lys-OMe. Subsequent [1H]-CPMG NMR experiments confirmed the binding of the peptides (peptides 3, 5, 9, and 16) on 14-3-3σ, with peptide 3 showing the strongest binding. Competitive [1H]-CPMG assays further revealed that while peptide 3 does not compete with a 14-3-3σ binding peptide (ExoS) for the protein's amphipathic groove, it was found to improve ExoS binding on 14-3-3σ. When 14-3-3σ was subjected to dynamic light scattering experiments, the 14-3-3σ homodimer was found to undergo dissociation into monomers prior to aggregation. Intriguingly, the presence of peptide 3 increased 14-3-3σ stability against aggregation. Overall, our findings suggest that (1) docking accompanied by MD simulations can be used to identify potential homodimer stabilizing compounds of 14-3-3σ and (2) peptide 3 can slow down 14-3-3σ aggregation (presumably by preventing its dissociation into monomers), as well as improving the binding of 14-3-3σ to ExoS protein.
The current study is motivated by the strict environmental regulations regarding the utilization and consumption of ecofriendly materials. In this context, the aim of this study has been to prepare and characterize different date palm tree (Phoenix dactylifera L.) fibers processed through the conventional water retting method. The chemical, elemental, crystallinity, thermal and morphological characterization of trunk (DPTRF), leaf stalk (DPLST), sheath or leaf sheath (DPLSH) and fruit bunch stalk (DPFBS) fibers was carried out. Chemical analysis revealed that the four types of date palm fibers display noteworthy differences in the content of cellulose, hemicellulose and lignin. Also, the amount of calcium is relatively high in all the date palm fibers; besides this, DPTRF exhibited 69.2% crystallinity, which is lower than that of DPLSH with 72.4% crystallinity. Moreover, DPLST and DPFBS fibers are more thermally stable (higher thermal degradation temperature) than DPTRF and DPLSH samples. Morphological analysis revealed that the fracture surface of DPFBS was relatively rougher, which would probably lead to increased bonding strength with polymers in composites. Overall, we conclude that DPFBS would be promising alternative sustainable and biomass material for the isolation of respective cellulose nanofibers and cellulose nanocrystals as potential reinforcement in polymer composites.
Many methods, including solid dispersion, micellization, and inclusion complexes, have been employed to increase the solubility of potent drugs. Beta-cyclodextrin (βCD) is a cyclic oligosaccharide consisting of seven glucopyranoside molecules, and is a widely used polymer for formulating soluble inclusion complexes of hydrophobic drugs. The enzymatic activity of Glycosyltransferase or α-amylase converts starch or its derivatives into a mixture of cyclodextrins. The βCD units are characterized by α -(1-4) glucopyranose bonds. Cyclodextrins possess certain properties that make them very distinctive because of their toroidal or truncated cage-like supramolecular configurations with multiple hydroxyl groups at each end. This allowed them to encapsulate hydrophobic compounds by forming inclusion complexes without losing their solubility in water. Chemical modifications and newer derivatives, such as methylated βCD, more soluble hydroxyl propyl methyl βCD, and sodium salts of sulfobutylether-βCD, known as dexolve® or captisol®, have envisaged the use of CDs in various pharmaceutical, medical, and cosmetic industries. The successful inclusion of drug complexes has demonstrated improved solubility, bioavailability, drug resistance reduction, targeting, and penetration across skin and brain tissues. This review encompasses the current applications of β-CDs in improving the disease outcomes of antimicrobials and antifungals as well as anticancer and anti-tubercular drugs.
The purification of thermo-acidic amylase enzyme from red pitaya (Hylocereus polyrhizus) peel for the first time was investigated using a novel aqueous two-phase system (ATPS) consisting of a thermo-separating copolymer and an organic solvent. The effectiveness of different parameters such as molecular weight of the thermo-separating ethylene oxide-propylene oxide (EOPO) copolymer and type and concentration of organic solvent on the partitioning behavior of amylase was investigated. In addition, the effects of phase components, volume ratio (VR), pH and crude load of purification factor and yield of amylase were evaluated to achieve the optimum partition conditions of the enzyme. In the novel ATPS method, the enzyme was satisfactorily partitioned into the polymer-rich top phase in the system composed of 30% (w/w) EOPO 2500 and 15% (w/w) 2-propanol, at a volume ratio of 1.94 and with a crude load scale of 25% (w/w) at pH 5.0. Recovery and recycling of components was also measured in each successive step of the ATPS process. The enzyme was successfully recovered by the method with a high purification factor of 14.3 and yield of 96.6% and copolymer was also recovered and recycled at a rate above 97%, making the method was more economical than the traditional ATPS method.
Supramolecular hydrogels, formed by noncovalent crosslinking of polymeric chains in water, constitute an interesting class of materials that can be developed specifically for drug delivery and biomedical applications. The biocompatibility, stimuli responsiveness to various external factors, and powerful functionalization capacity of these polymeric networks make them attractive candidates for novel advanced dosage form design.
Nowadays, pultruded glass fiber-reinforced polymer composite (PGFRPC) structures have been used widely for cross-arms in high transmission towers. These composite structures have replaced cross-arms of conventional materials like wood due to several factors, such as better strength, superior resistance to environmental degradation, reduced weight, and comparatively cheaper maintenance. However, lately, several performance failures have been found on existing cross-arm members, caused by moisture, temperature changes in the atmosphere, and other environmental factors, which may lead to a complete failure or reduced service life. As a potential solution for this problem, enhancing PGFRPC with honeycomb-filled composite structures will become a possible alternative that can sustain a longer service life compared to that of existing cross-arms. This is due to the new composite structures' superior performance under mechanical duress in providing better stiffness, excellence in flexural characteristics, good energy absorption, and increased load-carrying capacity. Although there has been a lack of previous research done on the enhancement of existing composite cross-arms in applications for high transmission towers, several studies on the enhancement of hollow beams and tubes have been done. This paper provides a state-of-the-art review study on the mechanical efficiency of both PGFRPC structures and honeycomb-filled composite sandwich structures in experimental and analytical terms.
Due to their high ionic conductivity, solid polymer electrolyte (SPE) systems have attracted wide spread attention as the most appropriate choice to fabricate all-solid-state electrochemical devices, namely batteries, sensors and fuel cells. In this work, ion conductive polymer electrolyte membranes have been prepared for battery fabrication. However, fractals were found to grow in these polymer electrolyte membranes weeks after they were prepared. It was believed that the formation of fractal aggregates in these membranes were due to ionic movement. The discovery of fractal growth pattern can be used to understand the effects of such phenomenon in the polymer electrolyte membranes. Digital images of the fractal growth patterns were taken and a simulation model was developed based on the Brownian motion theory and a fractal dialect known as L-system. A computer coding has been designed to simulate and visualize the fractal growth.
Solid polymer electrolytes comprised of various weight percent ratios of poly(ethyl methacrylate) (PEMA) and lithium perchlorate (LiClO4) salt were prepared via solution casting technique using N,N-dimethylformamide (DMF) as the solvent. The conductivity values of the electrolytes were determined via impedance spectroscopy. The conductivity of the PEMA-LiClO4 electrolytes increased with increasing salt concentration and the highest conductivity obtained was in the order of 10-6 S cm-1 at salt concentration of 20 wt%. The conductivity decreased for higher salt concentration. In order to understand the conductivity behavior, XRD and dielectric studies were done. The results showed that the conductivity was influenced by the fraction of amorphous region and number of charge carriers in the system. The transference number measurement was also performed on the highest conducting electrolyte systems. The result of the measurement indicated that the systems were ionic conductors.
The present article evaluates the composition and synthesis of hydrogel beads. Hydrogels, owing to their known biocompatibility, are widely used in drug delivery as a host (or drug carrier). Hydrogels, owing to their physical, chemical and biological properties, are popular in many aspects. Hydrogels are crosslinked-hydrophilic polymers and commercialized/synthesized in both natural and synthetic forms. These polymers are compatible with human tissues, therefore can be potentially used for biomedical treatments. Hydrogels in drug delivery offer several points of interest such as sustainability, and sensitivity without any side-effects as compared to traditional methods in this field. Drugs can encapsulate and release continuously into the targets when hydrogels are activated/modified magnetically or by fluorescent materials. It is crucial to develop new crosslinked polymers in terms of "biocompatibility" and "biodegradability" for novel drug delivery platforms. In the event that the accomplishments of the past can be used into the longer terms, it is exceedingly likely that hydrogels with a wide cluster of alluring properties can be synthesized. The current review, offers an updated summary of latest developments in the nanomedicines field as well as nanobased drug delivery systems over broad study of the discovery/ application of nanomaterials in improving both the efficacy of drugs and targeted delivery of them. The challenges/opportunities of nanomedicine in drug delivery also discussed. SCOPE OF THE RESEARCH: Although several reviews have been published in the field of hydrogels, however many of them have just centralized on the general overviews in terms of "synthesis" and "properties". The utilization of hydrogels and hydrogel-based composites in vital applications have been achieved a great interest. In this review, our aim is to recap of the key points in the field of hydrogels such as; a) hydrogel nanocomposites, b) magnetic beads, c) biomedical applications, and d) drug delivery. In the same vein, these outlines will be expanded with emphasizing on the boon of magnetic beads and recent developments in this area.
Biomolecules have been widely investigated as potential therapeutics for various diseases. However their use is limited due to rapid degradation and poor cellular uptake in vitro and in vivo. To address this issue, we synthesized a new nano-carrier system comprising of cholic acid-polyethylenimine (CA-PEI) copolymer micelles, via carbodiimide-mediated coupling for the efficient delivery of small interfering ribonucleic acid (siRNA) and bovine serum albumin (BSA) as model protein. The mean particle size of siRNA- or BSA-loaded CA-PEI micelles ranged from 100-150 nm, with zeta potentials of +3-+11 mV, respectively. Atomic force, transmission electron and field emission scanning electron microscopy demonstrated that the micelles exhibited excellent spherical morphology. No significant morphology or size changes were observed in the CA-PEI micelles after siRNA and BSA loading. CA-PEI micelles exhibited sustained release profile, the effective diffusion coefficients were successfully estimated using a mathematically-derived cylindrical diffusion model and the release data of siRNA and BSA closely fitted into this model. High siRNA and BSA binding and loading efficiencies (95% and 70%, respectively) were observed for CA-PEI micelles. Stability studies demonstrated that siRNA and BSA integrity was maintained after loading and release. The CA-PEI micelles were non cytotoxic to V79 and DLD-1 cells, as shown by alamarBlue and LIVE/DEAD cell viability assays. RT-PCR study revealed that siRNA-loaded CA-PEI micelles suppressed the mRNA for ABCB1 gene. These results revealed the promising potential of CA-PEI micelles as a stable, safe, and versatile nano-carrier for siRNA and the model protein delivery.
Multidrug resistance poses a great challenge to cancer treatment. In order to improve the targeting and codelivery of small interfering RNA (siRNA) and doxorubicin, and to overcome multidrug resistance, we conjugated a cholic acid-polyethylenimine polymer with folic acid, forming CA-PEI-FA micelles. CA-PEI-FA exhibited a low critical micelle concentration (80 μM), small average particle size (150 nm), and positive zeta potential (+ 12 mV). They showed high entrapment efficiency for doxorubicin (61.2 ± 1.7%, w/w), forming D-CA-PEI-FA, and for siRNA, forming D-CA-PEI-FA-S. X-ray photoelectron spectroscopic analysis revealed the presence of external FA on D-CA-PEI-FA micelles. About 25% doxorubicin was released within 24 h at pH 7.4, while more than 30% release was observed at pH 5. The presence of FA enhanced micelle antitumor activity. The D-CA-PEI-FA and D-CA-PEI-FA-S micelles inhibited tumor growth in vivo. No significant differences between their in vitro cytotoxic activities or their in vivo antitumor effects were observed, indicating that the siRNA coloading did not significantly increase the antitumor activity. Histological analysis revealed that tumor tissues from mice treated with D-CA-PEI-FA or D-CA-PEI-FA-S showed the lowest cancer cell density and the highest levels of apoptosis and necrosis. Similarly, the livers of these mice exhibited the lowest level of dihydropyrimidine dehydrogenase among all treated groups. The lowest serum vascular endothelial growth factor level (VEGF) (24.4 pg/mL) was observed in mice treated with D-CA-PEI-FA-S micelles using siRNA targeting VEGF. These findings indicated that the developed CA-PEI-FA nanoconjugate has the potential to achieve targeted codelivery of drugs and siRNA.
This study has applied the concept of the hybrid PAC-UF process in the treatment of the final effluent of the palm oil industry for reuse as feedwater for low-pressure boilers. In a bench-scale set-up, a low-cost empty fruit bunch-based powdered activated carbon (PAC) was employed for upstream adsorption of biotreated palm oil mill effluent (BPOME) with the process conditions: 60 g/L dose of PAC, 68 min of mixing time and 200 rpm of mixing speed, to reduce the feedwater strength, alleviate probable fouling of the membranes and thus improve the process flux (productivity). Three polyethersulfone ultrafiltration membranes of molecular weight cut-off (MWCO) of 1, 5 and 10 kDa were investigated in a cross-flow filtration mode, and under constant transmembrane pressures of 40, 80, and 120 kPa. The permeate qualities of the hybrid processes were evaluated, and it was found that the integrated process with the 1 kDa MWCO UF membrane yielded the best water quality that falls within the US EPA reuse standard for boiler-feed and cooling water. It was also observed that the permeate quality is fit for extended reuse as process water in the cement, petroleum and coal industries. In addition, the hybrid system's operation consumed 37.13 Wh m(-3) of energy at the highest applied pressure of 120 kPa, which is far lesser than the typical energy requirement range (0.8-1.0 kWh m(-3)) for such wastewater reclamation.
Trypsin has been immobilized by adsorption onto Amberlite XAD-7 beads. The Michaelis constant (Km) of the enzyme was increased about sevenfold following the immobilization. Its rate of penetration into the porous beads was determined by staining the beads, which had been split, with naphthol blue black. The extent of diffusional rate limitation of immobilized trypsin was related to the penetration depth of the enzyme into the beads. This can be controlled by manipulating the conditions during the preparation of the immobilized enzyme.
Foamed concrete (FC) is a high-quality building material with densities from 300 to 1850 kg/m3, which can have potential use in civil engineering, both as insulation from heat and sound, and for load-bearing structures. However, due to the nature of the cement material and its high porosity, FC is very weak in withstanding tensile loads; therefore, it often cracks in a plastic state, during shrinkage while drying, and also in a solid state. This paper is the first comprehensive review of the use of man-made and natural fibres to produce fibre-reinforced foamed concrete (FRFC). For this purpose, various foaming agents, fibres and other components that can serve as a basis for FRFC are reviewed and discussed in detail. Several factors have been found to affect the mechanical properties of FRFC, namely: fresh and hardened densities, particle size distribution, percentage of pozzolanic material used and volume of chemical foam agent. It was found that the rheological properties of the FRFC mix are influenced by the properties of both fibres and foam; therefore, it is necessary to apply an additional dosage of a foam agent to enhance the adhesion and cohesion between the foam agent and the cementitious filler in comparison with materials without fibres. Various types of fibres allow the reduction of by autogenous shrinkage a factor of 1.2-1.8 and drying shrinkage by a factor of 1.3-1.8. Incorporation of fibres leads to only a slight increase in the compressive strength of foamed concrete; however, it can significantly improve the flexural strength (up to 4 times), tensile strength (up to 3 times) and impact strength (up to 6 times). At the same time, the addition of fibres leads to practically no change in the heat and sound insulation characteristics of foamed concrete and this is basically depended on the type of fibres used such as Nylon and aramid fibres. Thus, FRFC having the presented set of properties has applications in various areas of construction, both in the construction of load-bearing and enclosing structures.
The objective of this work was to study the influence of cellulose nanofibrils (CNF) on the physical, mechanical, and thermal properties of Jatropha oil-based waterborne polyurethane (WBPU) nanocomposite films. The polyol to produce polyurethane was synthesized from crude Jatropha oil through epoxidation and ring-opening method. The chain extender, 1,6-hexanediol, was used to improve film elasticity by 0.1, 0.25, and 0.5 wt.% of CNF loading was incorporated to enhance film performance. Mechanical performance was studied using a universal test machine as specified in ASTM D638-03 Type V and was achieved by 0.18 MPa at 0.5 wt.% of CNF. Thermal gravimetric analysis (TGA) was performed to measure the temperature of degradation and the chemical crosslinking and film morphology were studied using Fourier-transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The results showed that when the CNF was incorporated, it was found to enhance the nanocomposite film, in particular its mechanical and thermal properties supported by morphology. Nanocomposite film with 0.5 wt.% of CNF showed the highest improvement in terms of tensile strength, Young's modulus, and thermal degradation. Although the contact angle decreases as the CNF content increases, the effect on the water absorption of the film was found to be relatively small (<3.5%). The difference between the neat WPBU and the highest CNF loading film was not more than 1%, even after 5 days of being immersed in water.
Molecular imprinting is an emerging technique to create imprinted polymers that can be applied in affinity-based separation, in particular, biomimetic sensors. In this study, the matrix of siloxane bonds prepared from the polycondensation of hydrolyzed tetraethoxysilane (TEOS) was employed as the inorganic monomer for the formation of a creatinine (Cre)-based molecularly imprinted polymer (MIP). Doped aluminium ion (Al(3+)) was used as the functional cross-linker that generated Lewis acid sites in the confined silica matrix to interact with Cre via sharing of lone pair electrons. Surface morphologies and pore characteristics of the synthesized MIP were determined by field emission scanning electron microscopy (FESEM) and Brunauer-Emmet-Teller (BET) analyses, respectively. The imprinting efficiency of MIPs was then evaluated through the adsorption of Cre with regard to molar ratios of Al(3+). A Cre adsorption capacity of up to 17.40 mg Cre g(-1) MIP was obtained and adsorption selectivity of Cre to its analogues creatine (Cr) and N-hydroxysuccinimide (N-hyd) were found to be 3.90 ± 0.61 and 4.17 ± 3.09, respectively. Of all the studied MIP systems, chemisorption was predicted as the rate-limiting step in the binding of Cre. The pseudo-second-order chemical reaction kinetic provides the best correlation of the experimental data. Furthermore, the equilibrium adsorption capacity of MIP fit well with a Freundlich isotherm (R (2) = 0.98) in which the heterogeneous surface was defined.
Magnesium-based polymer gel electrolytes consist of magnesium triflate (MgTf) salt, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) solvents as well as cellulose acetate as a polymeric agent were prepared via direct dissolution method. The highest ionic conductivity obtained for MgTf-EC:DEC(1:1) liquid electrolytes was 2.66 x 10-3 S cm-1 and enhanced to 2.73 x 10-3 S cm-1 with the addition of cellulose acetate. These results were in agreement with the activation energy obtained with the lowest value of 0.11. The best explanation on the enhancement in ionic conductivity of PGE is due to the “breathing polymeric chain model”. The plots of conductivity-temperature shown to obey an Arrhenius rule. The electrical properties of the sample with the highest conductivity were analyzed using electrical permittivity-based frequency and temperature dependence in the range of 100 Hz - 1 MHz and 303-373K, respectively. The variation in dielectric permittivity (εr and εi) as a function of frequency at different temperatures exhibited decays at higher frequencies and a dispersive behavior at low frequencies. Based on the observed electrical properties, it can be inferred that this polymer gel electrolyte could be a promising candidate as an electrolyte in electrochemical devices.
In this work, we reported the synthesis, characterization and adsorption study of two β-cyclodextrin (βCD) cross-linked polymers using aromatic linker 2,4-toluene diisocyanate (2,4-TDI) and aliphatic linker 1,6-hexamethylene diisocyanate (1,6-HDI) to form insoluble βCD-TDI and βCD-HDI. The adsorption of 2,4-dinitrophenol (DNP) on both polymers as an adsorbent was studied in batch adsorption experiments. Both polymers were well characterized using various tools that include Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller analysis and scanning electron microscopy, and the results obtained were compared with the native βCD. The adsorption isotherm of 2,4-DNP onto polymers was studied. It showed that the Freundlich isotherm is a better fit for βCD-TDI, while the Langmuir isotherm is a better fit for βCD-HMDI. The pseudo-second-order kinetic model represented the adsorption process for both of the polymers. The thermodynamic study showed that βCD-TDI polymer was more favourable towards 2,4-DNP when compared with βCD-HDI polymer. Under optimized conditions, both βCD polymers were successfully applied on various environmental water samples for the removal of 2,4-DNP. βCD-TDI polymer showed enhanced sorption capacity and higher removal efficiency (greater than 80%) than βCD-HDI (greater than 70%) towards 2,4-DNP. The mechanism involved was discussed, and the effects of cross-linkers on βCD open up new perspectives for the removal of toxic contaminants from a body of water.
Chemical recycling of bio-based polymers polyhydroxyalkanoates (PHAs) by thermal degradation was investigated from the viewpoint of biorefinery. The thermal degradation resulted in successful transformation of PHAs into vinyl monomers using alkali earth compound (AEC) catalysts. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)s (PHBVs) were smoothly and selectively depolymerized into crotonic (CA) and 2-pentenoic (2-PA) acids at lower degradation temperatures in the presence of CaO and Mg(OH)(2) as catalysts. Obtained CA from 3-hydroxybutyrate sequences in PHBV was copolymerized with acrylic acid to produce useful water-soluble copolymers, poly(crotonic acid-co-acrylic acid) that have high glass-transition temperatures. The copolymerization of CA derived from PHA pyrolysis is an example of cascade utilization of PHAs, which meets the idea of sustainable development.