Enzymes of commercial importance, such as lipase, amylase, laccase, phytase, carbonic anhydrase, pectinase, maltase, glucose oxidase etc., show multifunctional features and have been extensively used in several fields including fine chemicals, environmental, pharmaceutical, cosmetics, energy, food industry, agriculture and nutraceutical etc. The deployment of biocatalyst in harsh industrial conditions has some limitations, such as poor stability. These drawbacks can be overcome by immobilizing the enzyme in order to boost the operational stability, catalytic activity along with facilitating the reuse of biocatalyst. Nowadays, functionalized polymers and composites have gained increasing attention as an innovative material for immobilizing the industrially important enzyme. The different types of polymeric materials and composites are pectin, agarose, cellulose, nanofibers, gelatin, and chitosan. The functionalization of these materials enhances the loading capacity of the enzyme by providing more functional groups to the polymeric material and hence enhancing the enzyme immobilization efficiency. However, appropriate coordination among the functionalized polymeric materials and enzymes of interest plays an important role in producing emerging biocatalysts with improved properties. The optimal coordination at a biological, physical, and chemical level is requisite to develop an industrial biocatalyst. Bio-catalysis has become vital aspect in pharmaceutical and chemical industries for synthesis of value-added chemicals. The present review describes the current advances in enzyme immobilization on functionalized polymers and composites. Furthermore, the applications of immobilized enzymes in various sectors including bioremediation, biosensor and biodiesel are also discussed.
The generation of free radicals is the key to the photocatalytic efficiency. In this study, the degradation mechanism of photoelectrocatalysis (PEC) membrane could be adequately explained by exploring the generation pathway of different free radicals. The PEC membrane was prepared by gas phase polymerization of poly (3, 4-ethylene dioxythiophene) (PEDOT) on non-woven fabric, industrial filter cloth, ceramic membrane and polyvinylidene fluoride (PVDF) membrane, respectively. Three-dimensional fluorescence test showed that the optimal degradation of mixed or monomer contamination (bovine serum protein, sodium humate, and sodium alginate) was achieved by modified ceramic membrane under PEC condition. As for self-cleaning experiment, the membrane resistance decreased 65.7% when the reaction conditions changed from dark to PEC for 30 min. Combined with the characterization results, PEDOT as photocapacitance extended electron lifetime and promoted free radical generation. This system was mainly dependent on superoxide free radicals (0.01 mmol/L) and singlet oxygen (0.10 mmol/L), which came from energy and electron transfer. Oxygen vacancy could adsorb oxygen to produce superoxide radicals, which was further oxidized to singlet oxygen. In addition, the π-electron conjugated system of PEDOT accelerated the hole transfer and the separation of electrons and holes. Also, this study provided a new view of reactive oxygen species generation mechanism from PEDOT modified membrane.
The paper evaluates the routes towards the evaluation of membranes using ZIF-62 metal organic framework (MOF) nano-hybrid dots for environmental remediation. Optimization of interaction of operating parameters over the rooted membrane is challenging issue. Subsequently, the interaction of operating parameters including temperature, pressure and CO2 gas concentration over the resultant rooted membranes are evaluated and optimized using response surface methodology for environmental remediation. In addition, the stability and effect of hydrocarbons on the performance of the resulting membrane during the gas mixture separation are evaluated at optimum conditions to meet the industrial requirements. The characterization results verified the fabrication of the ZIF-62 MOF rooted composite membrane. The permeation results demonstrated that the CO2 permeability and CO2/CH4 selectivity of the composite membrane was increased from 15.8 to 84.8 Barrer and 12.2 to 35.3 upon integration of ZIF-62 nano-glass into cellulose acetate (CA) polymer. Subsequently, the optimum conditions have been found at a temperature of 30 °C, the pressure of 12.6 bar and CO2 feed concentration of 53.3 vol%. These optimum conditions revealed the highest CO2 permeability, CH4 permeability and CO2/CH4 separation factor of 47.9 Barrer, 0.2 Barrer and 26.8. The presence of hydrocarbons in gas mixture dropped the CO2 permeability of 56.5% and separation factor of 46.4% during 206 h of testing. The separation performance of the composite membrane remained stable without the presence of hydrocarbons for 206 h.
A simple, ready-to-use concentrated specimen smear microscopy method employing a nanometer silicon polyvinylidene fluoride (PVDF) polymer membrane sandwich filtration vessel to concentrate acid-fast bacilli (AFB) in samples (SFV-CSSM, Hunan-Tech New Medical System Co. Ltd. China) was compared with direct sputum smear microscopy (DSSM) to determine its performance using culture on modified Ogawa agar as reference. The results for 4114 clinical samples collected from health facilities in Sabah were interpreted with reference to culture results, sample collection-transportation conditions and clinical data including responses to anti-TB drug treatment. The SFV-CSSM showed higher sensitivity than DSSM (79.4% versus 60.5%) and less background interference. Its ability to detect low levels of AFB at an affordable cost makes it an excellent tool for the screening of pauci-bacillary samples as well as for active case finding in TB control programs.
Tetracycline is a potentially hazardous residual antibiotic detected in various sewages. High concentration (mg/L) of tetracycline is found in pharmaceutical/hospital wastewater and wastewater derived from livestock and poultry. So far, only antibiotics in μg/L level have been reported in granulation of aerobic sludge during wastewater treatment, but its effects in high concentration are rarely reported. In this study, the influence of tetracycline in high concentration (∼2 mg/L) on the formation of granular sludge, structure, and metabolic function of the microbial community during the granulation of aerobic sludge was investigated to improve the understanding of the aerobic granular sludge formation under high-level of tetracycline. The role of extracellular polymers substances (EPSs) derived from granular sludge in the granulation and tetracycline removal process was also investigated, showing that tetracycline improved the relative hydrophobicity, flocculability and protein/polysaccharide ratio of EPSs, accelerating the granulation of sludge. Succession of microbial communities occurred during the domestication of functional bacteria present in the sludge and was accompanied with regulation of metabolic function. The addition of tetracycline lead to an increase of tetracycline-degrading bacteria or antibiotic resistance genus. Those findings provide new perspectives of the influence of tetracycline on aerobic sludge granulation and the removal mechanism of tetracycline.
Nanocellulose based gas barrier materials have become an increasingly important subject, since it is a widespread environmentally friendly natural polymer. Previous studies have shown that super-high gas barrier can be achieved with pure and hierarchical nanocellulose films fabricated through simple suspension or layer-by-layer technique either by itself or incorporating with other polymers or nanoparticles. Improved gas barrier properties were observed for nanocellulose-reinforced composites, where nanocellulose partially impermeable nanoparticles decreased gas permeability effectively. However, for nanocellulose-based materials, the higher gas barrier performance is jeopardized by water absorption and shape deformation under high humidity conditions which is a challenge for maintaining properties in material applications. Thus, numerous investigations have been done to solve the problem of water absorption in nanocellulose-based materials. In this literature review, gas barrier properties of pure, layer-by-layer and composite nanocellulose films are investigated. The possible theoretical gas barrier mechanisms are described, and the prospects for nanocellulose-based materials are discussed.
Diabetic wound (DW) is a secondary application of uncontrolled diabetes and affects about 42.2% of diabetics. If the disease is left untreated/uncontrolled, then it may further lead to amputation of organs. In recent years, huge research has been done in the area of wound dressing to have a better maintenance of DW. These include gauze, films, foams or, hydrocolloid-based dressings as well as polysaccharide- and polymer-based dressings. In recent years, scaffolds have played major role as biomaterial for wound dressing due to its tissue regeneration properties as well as fluid absorption capacity. These are three-dimensional polymeric structures formed from polymers that help in tissue rejuvenation. These offer a large surface area to volume ratio to allow cell adhesion and exudate absorbing capacity and antibacterial properties. They also offer a better retention as well as sustained release of drugs that are directly impregnated to the scaffolds or the ones that are loaded in nanocarriers that are impregnated onto scaffolds. The present review comprehensively describes the pathogenesis of DW, various dressings that are used so far for DW, the limitation of currently used wound dressings, role of scaffolds in topical delivery of drugs, materials used for scaffold fabrication, and application of various polymer-based scaffolds for treating DW.
Polyurethane, as a rubber material, can relieve the load on the ground and provide seismic design for the venue, which is of great significance for sports venues. In order to improve the seismic resistance and abrasion resistance of materials for sports fields and reduce accidents in sports, this article has carried out research on the polyurethane elastomer layered nanocomposites for sports fields and their preparation. Today's world is a challenging era of science and technology. The fields of biotechnology, information, medicine, energy, environment, and national defense and security are closely related to the development of high tech, and the requirements for materials are becoming increasingly diversified. Polymer nanocomposite coating has the dual characteristics of organic and inorganic components. It not only retains the advantages of a polymer but also endows it with versatility. It meets the current application needs. It is a hot spot in today's research. Among them, there are two major problems in the composite process of nanomaterials and polymers: dispersion and compatibility. How to improve the dispersion of nanoparticles and enhance the compatibility between nanoparticles and polymers is an urgent problem to be solved. In the method part, this article introduces a small amount of polyurethane and polyurethane elastomers formed after polyurethane modification and introduces layered compounds and nanocomposites and introduces several models involved in nanomaterials in terms of algorithms. In the analysis part, this paper conducts a comprehensive analysis of the hard segment mass fraction, mechanical properties, thermal decomposition behavior, degradation mechanism, and dynamic mechanical properties. With the increase of GO content, the tensile strength increases significantly and the elongation at break becomes smaller and smaller. When the GO content increases from 0% to 2%, the tensile properties of the WPU film increase from 2.6 MPa to 7.9 MPa and the fracture of the elongation decreased from 201.7% to 62.8%. This shows that the increase in GO content will make the composite material harder and brittle. It can be seen from the experimental results that the preparation of the polyurethane elastomer layered nanocomposite material designed in this paper has a good application effect on sports venues.
Biocomposites are materials that are easy to manufacture and environmentally friendly. Sugar palm fibre (SPF) is considered to be an emerging reinforcement candidate that could provide improved mechanical stiffness and strength to the biocomposites. Numerous studies have been recently conducted on sugar palm biocomposites to evaluate their physical, mechanical and thermal properties in various conditions. Sugar palm biocomposites are currently limited to the applications of traditional household products despite their good thermal stability as a prospective substitute candidate for synthetic fibres. Thus, thermal analysis methods such as TGA and DTG are functioned to determine the thermal properties of single fibre sugar palm composites (SPCs) in thermoset and thermoplastic matrix as well as hybrid SPCs. The biocomposites showed a remarkable change considering thermal stability by varying the individual fibre compositions and surface treatments and adding fillers and coupling agents. However, literature that summarises the thermal properties of sugar palm biocomposites is unavailable. Particularly, this comprehensive review paper aims to guide all composite engineers, designers, manufacturers and users on the selection of suitable biopolymers for sugar palm biocomposites for thermal applications, such as heat shields and engine components.
In this study, poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) dual-layer membranes filled with 0-3 wt% cellulose nanowhisker (CNWs) were fabricated with aim to remove metal ions from wastewater. An integrated method was employed in the membrane fabrication process by combining water vapor-induced and crystallization-induced phase inversions. The membrane thickness was measured in between 11 and 13 μm, which did not pose significant flux deviation during filtration process. The 3% CNW filled membrane showed prominent and well-laminated two layers structure. Meanwhile, the increase in CNWs from 0 to 3% loadings could improve the membrane porosity (43-74%) but reducing pore size (2.45-0.54 μm). The heat resistance of neat membrane enhanced by 1% CNW but decreased with loadings of 2-3% CNWs due to flaming behavior of sulphated nanocellulose. Membrane with 3% CNW displayed the tensile strength (23.5 MPa), elongation at break (7.1%), and Young's modulus (0.75 GPa) as compared to other samples. For wastewater filtration performance, the continuous operation test showed that 3% CNW filled membrane exhibited the highest removal efficiency for both cobalt and nickel metal ions reaching to 83% and 84%, respectively. We concluded that CNWs filled dual-layer membranes have potential for future development in the removal of heavy metal ions from wastewater streams.
In the current study, a phase inversion scheme was employed to fabricate hydroxyapatite (HA)/polysulfone (PSF)-based asymmetric membranes using a film applicator with water as a solvent and nonsolvent exchanging medium. Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) spectroscopic studies were conducted to confirm the bonding chemistry and purity of filler. The inherent thick nature of PSF generated sponge-like shape while the instantaneous demixing process produced finger-like pore networks in HA/PSF-based asymmetric membranes as exhibited by scanning electron microscope (SEM) micrographs. The FTIR spectra confirmed noncovalent weak attractions toward the polymer surface. The leaching ratio was evaluated to observe the dispersion behavior of HA filler in membrane composition. Hydrophilicity, pore profile, pure water permeation (PWP) flux, and molecular weight cutoff (MWCO) values of all formulated membranes were also calculated. Antifouling results revealed that HA modified PSF membranes exhibited 43% less adhesion of bovine serum albumin (BSA) together with >86% recovery of flux. Membrane composition showed 74% total resistance, out of which 60% was reversible resistance. Biocompatibility evaluation revealed that the modified membranes exhibited prothrombin time (PT), and thrombin time (TT) comparable with typical blood plasma, whereas proliferation of living cells over membrane surface proved its nontoxic behavior toward biomedical application. The urea and creatinine showed effective adsorption aptitude toward HA loaded PSF membranes.
Bioadhesive polymers offer versatility to medical and pharmaceutical inventions. The incorporation of such materials to conventional dosage forms or medical devices may confer or improve the adhesivity of the bioadhesive systems, subsequently prolonging their residence time at the site of absorption or action and providing sustained release of actives with improved bioavailability and therapeutic outcomes. For decades, much focus has been put on scientific works to replace synthetic polymers with biopolymers with desirable functional properties. Gelatine has been considered one of the most promising biopolymers. Despite its biodegradability, biocompatibility and unique biological properties, gelatine exhibits poor mechanical and adhesive properties, limiting its end-use applications. The chemical modification and blending of gelatine with other biomaterials are strategies proposed to improve its bioadhesivity. Here we discuss the classical approaches involving a variety of polymer blends and composite systems containing gelatine, and gelatine modifications via thiolation, methacrylation, catechol conjugation, amination and other newly devised strategies. We highlight several of the latest studies on these strategies and their relevant findings.
In this work, new selective and sensitive dual-template molecularly imprinted polymer nanoparticles (MIPs) were synthesized and characterized. Sorbent MIPs were investigated for simultaneous extraction and clean-up of thiamethoxam and thiacloprid from light and dark honey samples. In this study, ultra-high-performance liquid chromatography-tandem mass spectrometry triple-quadrupole (UHPLC-MS/MS) (QQQ) was used to detect and quantify the pesticides. The kinetic model with adsorption kinetics of sorbent was investigated. The optimal adsorption conditions were 80 mg of polymer MIPs, a 30-min extraction time, and a pH of 7. The detection limit (LOD) and the quantification limit (LOQ) varied from 0.045 to 0.070 µg kg-1 and from 0.07 to 0.10 µg kg-1, respectively. The intra-day and inter-day precision (RSD, %) ranged from 1.3 to 2.0% and from 8.2 to 12.0%, respectively. The recovery of thiamethoxam and thiacloprid ranged from 96.8 to 106.5% and 95.3 to 104.4%, respectively, in light and dark honey samples.
Oil spills are a major contributor to water contamination, which sets off a significant impact on the environment, biodiversity, and economy. Efficient removal of oil spills is needed for the protection of marine species as well as the environment. Conventional approaches are not efficient enough for oil-water separation; therefore, effective strategies and efficient removal techniques (and materials) must be developed to restore the contaminated marine to its normal ecology. Several research studies have shown that nanotechnology provides efficient features to clean up these oil spills from the water using magnetic nanomaterials, particularly carbon/polymer-based magnetic nanocomposites. Surface modification of these nanomaterials via different techniques render them with salient innovative features. The present review discusses the advantages and limitations of conventional and advanced techniques for the oil spills removal from wastewater. Furthermore, the synthesis of magnetic nanocomposites, their utilization in oil-water separation, and adsorption mechanisms are discussed. Finally, the advancement and future perspectives of magnetic nanocomposites (particularly of carbon and polymer-based magnetic nanocomposites) in environmental remediation are presented.
Poly(lactic acid) (PLA), a bio-based polyester, has been extensively investigated in the recent past owing to its excellent mechanical properties. Several studies have been conducted on PLA blends, with a focus on improving the brittleness of PLA to ensure its suitability for various applications. However, the increasing use of PLA has increased the contamination of PLA-based products in the environment because PLA remains intact even after three years at sea or in soil. This review focuses on analyzing studies that have worked on improving the degradation properties of PLA blends and studies how other additives affect degradation by considering different degradation media. Factors affecting the degradation properties, such as surface morphology, water uptake, and crystallinity of PLA blends, are highlighted. In natural, biotic, and abiotic media, water uptake plays a crucial role in determining biodegradation rates. Immiscible blends of PLA with other polymer matrices cause phase separation, increasing the water absorption. The susceptibility of PLA to hydrolytic and enzymatic degradation is high in the amorphous region because it can be easily penetrated by water. It is essential to study the morphology, water absorption, and structural properties of PLA blends to predict the biodegradation properties of PLA in the blends.
Conformational search for the most stable geometry connection of 16 sets of polydopamine (PDA) tetramer subunits has been systematically investigated using density functional theory (DFT) calculations. Our results indicated that the more planar subunits are, the more stable they are. This finding is in good agreement with recent experimental observations, which have suggested that PDA are composed of the nearly planar subunits that appear to be stacked together via the π-π interactions to form graphite-like layered aggregates associated with the balance of the intramolecular hydrogen bonds and steric effects from the indole and catechol moieties. Molecular dynamics (MD) simulations of 16 spherical clusters of the tetramer subunits of PDA in the gas and aqueous phase were performed at 298 K and confirmed the stability of supramolecular tetramer aggregates. The complex formation and binding energy of all 16 clusters are very strong although the shapes of the clusters in aqueous solution are not spherical and are very much different from those in the gas phase. The aggregations of all 16 clusters in aqueous solution were also confirmed from the profiles of the Kratky plot and the radius of gyration of all clusters. Our MD results in both gas phase and aqueous solution pointed out that there are high possibilities of aggregations of the 16 kinds of tetramer subunits although the conformations of each tetramer subunit are not flat. In summary, this work brings an insight into the controversial structure of PDA tetramer units and explains some of the important structural features found in the aqueous phase in comparison to the gas phase.
Viral respiratory tract infections have significantly impacted global health as well as socio-economic growth. Respiratory viruses such as the influenza virus, respiratory syncytial virus (RSV), and the recent SARS-CoV-2 infection (COVID-19) typically infect the upper respiratory tract by entry through the respiratory mucosa before reaching the lower respiratory tract, resulting in respiratory disease. Generally, vaccination is the primary method in preventing virus pathogenicity and it has been shown to remarkably reduce the burden of various infectious diseases. Nevertheless, the efficacy of conventional vaccines may be hindered by certain limitations, prompting the need to develop novel vaccine delivery vehicles to immunize against various strains of respiratory viruses and to mitigate the risk of a pandemic. In this review, we provide an insight into how polymer-based nanoparticles can be integrated with the development of vaccines to effectively enhance immune responses for combating viral respiratory tract infections.
Orally disintegrating tablet (ODT) is a user friendly and convenient dosage form. The study aimed to investigate the effect of polymers and wheat starch on the tablet properties of lyophilized ODT, with dapoxetine as model drug. Three polymers (hydroxypropylmethyl cellulose, carbopol 934P and Eudragit® EPO) and wheat starch were used as matrix forming materials in preparation of lyophilized ODT. The polymeric dispersion was casted into a mould and kept in a freezer at -20 °C for 4 h before freeze dried for 12 h. It was found that increasing in HPMC and Carbopol 934P concentrations produced tablets with higher hardness and longer disintegration time. In contrast, Eudragit® EPO was unable to form tablet with sufficient hardness at various concentrations. Moreover, HPMC seems to have a stronger effect on tablet hardness compared to Carbopol 934P at the same concentration level. ODT of less friable was obtained. Wheat starch acted as binder which strengthen the hardness of ODTs and prolonged the disintegration time. ODT comprising of HPMC and wheat starch at ratio of 2:1 was found to be optimum based upon the tablet properties. The optimum formulation was palatable and 80 % of the drug was released within 30 min in the dissolution study.
This study reports the influence of peste des petits ruminants (PPR) vaccination on the clinico-pathological outcomes of PPR in the face of an outbreak. Twenty-two West African dwarf goats procured for a different study started showing early signs of PPR during acclimatization. In response, PPR vaccine was administered either intranasally with phytogenic mucoadhesive gum (Group A; n = 6) or without gum (Group B; n = 6); subcutaneously (Group C; n = 6) or not vaccinated (Group D; n = 4) and studied for 21 days. The clinical scores, hematology, serology and pathology scores were evaluated. Clinical signs of PPR were present in all groups, presenting a percentage mortality of 33%; 33%; 64% and 100% for Groups A, B, C, and D, respectively. Polycythemia and mild leukopenia were observed in all groups, and all animals were seropositive by day 7 post-vaccination. The lung consolidation scores were low in Groups A and B, compared to Group C. Histopathological lesions consistent with PPR was observed in the lymphoid organs, gastrointestinal tract, and lungs with the presence of PPR antigen as detected by immunohistochemistry. The findings suggest that intranasal vaccination with or without mucoadhesive gum may influence the outcome of PPR infection more than the subcutaneous route in the face of an outbreak.
An innovative nano-base polymer that scavenges radicals and reactive oxygen species exhibits potential antibacterial properties, which are crucial in the biomedical field, particularly in reducing nosocomial infections. However, the safety of this nano-based polymer, which has direct contact with the human system, has not been fully understood. The present study investigated the cytocompatibility and hemocompatibility responses of linear low-density polyethylene polymer (LLDPE) embedded with difference ratios of heterogeneous TiO2/ZnO nanocomposites. Exposure of the blood and fibroblast cells to LLDPE/100Z and LLDPE/25T75Z/10% nanocomposite films for 48 and 72 h decreased their viability by less than 40%, compared with LLDPE, LLDPE/100T and LLDPE/25T75Z/5% nanocomposite films. It also presented possible cellular damage and cytotoxicity, which was supported by the findings from the significant release of extracellular lactate dehydrogenase profiles and cell survival assay Further observation using an electron microscope revealed that LLDPE films with heterogeneous 25T75Z/5% promoted cell adhesion. Moreover, no hemolysis was detected in all ratios of heterogeneous TiO2/ZnO nanocomposite in LLDPE film as it was less than 0.2%, suggesting that these materials were hemocompatible. This study on LLDPE film with heterogeneous TiO2/ZnO nanocomposites demonstrated favorable biocompatible properties that were significant for advanced biomedical polymer application in a hospital setting.