Novel Sustainable Cellulose Acetate Based Biosensor for Glucose Detection

In this study,green zinc oxide(ZnO)/polypyrrole(Ppy)/cellulose acetate(CA)film has been synthesized via solvent casting.This film was used as supporting material for glucose oxidase(GOx)to sensitize a glucose biosensor.ZnO nanoparticles have been prepared via the green route using olive leaves extract as a reductant.ZnO/Ppy nanocomposite has been synthesized by a simple in-situ chemical oxidative polymerization of pyrrole(Py)monomer using ferric chloride(FeCl3)as an oxidizing agent.The produced materials and the composite films were characterized using X-ray diffraction analysis(XRD),scanning electron microscope(SEM),Fourier transform infrared(FTIR)and thermogravimetric analysis(TGA).Glucose oxidase was successfully immobilized on the surface of the prepared film and then ZnO/Ppy/CA/GOx composite was sputtered with platinum electrode for the current determination at different initial concentrations of glucose.Current measurements proved the suitability and the high sensitivity of the constructed biosensor for the detection of glucose levels in different samples.The performance of the prepared biosensor has been assessed by measuring and comparing glucose concentrations up to 800 ppm.The results affirmed the reliability of the developed biosensor towards real samples which suggests the wide-scale application of the proposed biosensor.

Research Progress of Environment Friendly Plasticizers for Cellulose Acetate Processing

Cellulose acetate(CA)is an important cellulose derivative that can undergo thermoplas-tic processing.Plasticizers can form stable hydrogen bonds with CA molecular chains,reducing intermolecular and intramolecular interactions,and play an important role in the melting processing of CA.In recent years,environmentally friendly plasticizers that are natural,non-toxic,odorless,low dissolution,and low migration have received increas-ing attention in plastic processing.This article reviews the research progress of environ-mentally friendly plasticizers such as natural plasticizers,ionic liquid plasticizers,citrate plasticizers,and polyethylene glycol plasticizers in the processing of cellulose acetate,and looks forward to the application prospects of environmentally friendly plasticizers.

Preparation of Cellulose Acetate Butyrate Porous Micro/Nanofibrous Membranes and Their Properties

Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibrous membranes with a large number of nanopores on the fiber surface were successfully prepared by electrospinning with dichloromethane(DCM)/acetone(AC)as the mixed solvent.Apparent morphology,porosity,moisture permeability,air permeability,static water contact angles,and thermal conductivity of the fibrous membranes were investigated at different spinning voltages.The results showed that with the increase of the spinning voltage,the average fiber diameter of the CAB porous micro/nanofibrous membranes gradually decreased and the fiber diameter distribution was more uniform.When the spinning voltage reached 40 kV,the porosity reached 91.38%,the moisture permeability was up to 7430 g/(m^(2)·d),the air permeability was up to 36.289 mm/s,the static water contact angle was up to 145.0°,while the thermal conductivity of the fibrous membranes reached 0.030 W/(m·K).The material can be applied as thermal-insulation,waterproof and moisture-permeable membranes.

Microporous Cyclodextrin Film with Funnel-type Channel Polymerized on Electrospun Cellulose Acetate Membrane as Separators for Strong Trapping Polysulfides and Boosting Charging in Lithium-Sulfur Batteries

The“shuttle effect”of polysulfides hampers the commercialization of lithium-sulfur(Li-S)batteries.Here,a thin molecular sieve film was decorated on the surface of an electrospun cellulose acetate(CA)membrane derived from recycled cigarette filters,where the truncated cone structureβ-cyclodextrin(β-CD)was selected as the building block to physically block and chemically trap polysulfides while simultaneously dramatically speeding up ion transport.Furthermore,on theβ-CD free side of the separator facing the cathode,graphite carbon(C)was sputtered as an upper current collector,which barely increases the thickness.These benefits result in an initial discharge performance of 1378.24 mAh g^(−1) and long-term cycling stability of 863.78 mAh g^(−1) after 1000 cycles at 0.2 C for the battery with theβ-CD/CA/C separator,which is more than three times that of the PP separator after 500 cycles.Surprisingly,the funnel-type channel ofβ-CD generates a differential ionic fluid pressure on both sides,speeding up ion transport by up to 69%,and a 65.3%faster charging rate of 9484 mA g^(−1) was achieved.The“funnel effect”of a separator is regarded as a novel and high-efficiency solution for fast charging of Li-S and other lithium secondary batteries.

Homogeneous modification of carbon nanotubes with cellulose acetate

An efficient strategy that comprised shorten, chain extension, active groups introducing and homogeneous reaction tactics, was adopted to modify multiwalled carbon nanotubes （MWNTs） with cellulose acetate （CA）. Specially, by utilizing 2,4,6-trichloro- 1,3,5-triazine, a reactive intermediate of the MWNTs （MWNT-triazine） was obtained. Suitable solubility of the MWNT-triazine helps make the homogeneous modification become reality. Detailed characterizations further verified that reaction between chloride atoms in the MWNT-triazine and hydroxyl groups in the CA had contributed to the formation of MWNT-CA conjugates. The novel MWNT-CA consists of carbon （76.3%）, oxygen （18.4%） and nitrogen （5.3%）. With a nanotube-attached CA content of 42.8 wt%, the MWNT-CA is readily soluble in DMSO, NMP, DMF and DMAc. Confirmation of the CA-based modification route might lead to studies aiming for specific sorption and isolation.

CHARACTERIZATION OF REGENERATED CELLULOSE MEMBRANES HYDROLYZED FROM CELLULOSE ACETATE

A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree of substitution, structure, porous properties, solubility and thermal stability on hydrolysis time was studied by chemical titration, Fourier transform infrared spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, respectively. The results indicated that the pore size of the regenerated cellulose membranes was slightly smaller than that of cellulose acetate membrane, while solvent-resistance, crystallinity and thermostability were significantly improved. This work provides a simple way to prepare the porous cellulose membranes, which not only kept the good pore characteristics of cellulose acetate membranes, but also possessed solvent-resistance, high crystallinity and thermostability. Therefore, the application range of cellulose acetate membranes can be expanded.

Development of Biofunctionalized Cellulose Acetate Nanoscaffolds for Heart Valve Tissue Engineering

Currently-used mechanical and biological heart valve prostheses have a satisfactory short-term performance, but may exhibit several major drawbacks on the long-term. Mechanical prostheses, based on carbon, metallic and polymeric components, require permanent anticoagulation treatment, and their usage often leads to adverse reactions, e.g. thromboembolic complications and endocarditis. In recent years, there is a need for a heart valve prosthesis that can grow, repair and remodel. The concept of tissue engineering offers good prospects into the development of such a device. An ideal scaffold should mimic the structural and purposeful profile of materials found in the natural extracellular matrix (ECM) architecture. The goal of this study was to develop cellulose acetate scaffolds (CA) for valve tissue regeneration. After their thorough physicochemical and biological characterization, a biofunctionalization process was made to increase the cell proliferation. Especially, the surface of scaffolds was amplified with functional molecules, such as RGD peptides (Arg-Gly-Asp) and YIGSRG laminins (Tyrosine-Isoleucine-Glycine-Serine-Arginine-Glycine) which immobilized through biotin-streptavidin bond, the strongest non-covalent bond in nature. Last step was to successfully coat an aortic metallic valve with CA biofunctionallized nanoscaffolds and cultivate cells in order to create an anatomical structure comparable to the native valve. Promising results have been obtained with CA-based nanoscaffolds. We found that cells grown successfully on the biofunctionalized valve surface thereby scaffolds that resemble the native tissues, elaborated with bioactive factors such as RGD peptides and laminins not only make the valve’s surface biocompatible but also they could promote endothyliazation of cardiac valves causing an anti-coagulant effect

Interfacial Properties of Ethyl Cellulose/Cellulose Acetate Blends by HPLC

The high performance liquid chromatography method (HPLC) with ethyl cellulose/cellulose acetate (EC/CA) blends and EC as column packing material, and small molecular weight compound as probe molecules was employed to measure the retention volume (VR) and equilibrium distribution coefficient (K) of both inorganic and organic solutes. The interfacial separation properties of EC/CA blends were characterized by the HPLC data. The effects of the blends on the interfacial adsorption properties, hydrophilicity, affinity, polar and non-polar parameters of EC membrane materials were studied subsequently. The research results indicate that the interfacial adsorption properties and hydrophilicity of EC have been improved by solution blending with CA. The alloys are superior to EC in the separation efficiency for non-dissociable polar organic solute. The EC/CA alloy (80:20, ω) is suitable for desalting and desaccharifying.

THERMAL BEHAVIOR OF THERMOTROPIC HYDROXYETHYL CELLULOSE ACETATE/POLYETHYLENE BLENDS

The thermal behavior of thermotropic hydroxyethyl cellulose acetate (HECA)/polyethylene (PE) blends has been studied by DSC. It is found that the blends of HECA and PE are immiscible but the crystallization of PE is affected by HECA chains in the blends with more than 50% HECA, which results in the subordinate crystallization of PE and the formation of imperfect structures in the PE crystals. The imperfection of PE crystals in the blends can be eliminated after annealing at 393K.

Evaluation of Several Procedures for Immobilizing Cholesterol Oxidase Based on Cellulose Acetate Membrane

Immobilized cholesterol oxidase (COD) membrane with higher catalytic activity is important for biosensor. In this paper, several procedures for immobilizing COD based on cellulose acetate (CA) membrane are studied. Reasons causing different catalytic activities are also discussed.

Application and Characterization of Cellulose Acetate Membrane Produced from Herbaceous Plant: Solidago Canadensis L.

In this work,the viability of Solidago Canadensis L. for cellulose acetate membrane production was tested. The cellulose was extracted from Solidago Canadensis L. stem by organic solvents,and the cellulose diacetate was obtained by acetylization of cellulose. The properties of the intermediate products of cellulose pulp and cellulose diacetate were characterized by FT-IR and XRD. Compared with commercial cellulose diacetate,the properties of cellulose diacetate were similar to those of the commercial cellulose diacetate. The cellulose acetate membrane with desirable pure water flux and rejection rate was obtained from cellulose diacetate by solution casting. The membrane showed favorable hydrophilic property so that it had good anti-pollution performance. The maximum pure water flux of the membrane was 27. 21 m L /( cm2· h) and the maximum rejection rate was 80. 39%. The results demonstrated that the membrane obtained from herbaceous plant: Solidago Canadensis L. had good performance of ultrafiltration.

COMPARISON OF CELLULOSE ACETATE POLYMER AND ELECTROLYTIC DETACHABLE COILS FOR TREATMENT OF CANINE ANEURYSMAL MODELS

Electrolytic detachable coils (EDC) have been the main embolic materi als for intracranial aneurysms. Liquid aneurysmal embolic materials represented by cellulose acetate polymer (CAP) are still in controversy. In this research, t he embolization results and pathological reactions after embolization of canine aneurysmal models with EDC or CAP were observed and compared. Methods. The canine aneurysmal models constructed by anastomosis of venous pouch es were randomly grouped. The aneurysms were respectively occluded with CAP and electrolytic detachable coils that was named by Wu electrolytic detachable coil (WEDC) and made by us. Angiogram follow ups were performed at 24 hour, 2 week , and 2 month after embolization. The occluded aneurysms were dissected in each stage for light microscopic, electron microscopic, and histochemical research. Results. The effect of embolization was significantly better with WEDC than that with CAP . Post embolized complications such as aneurysm rupture and stenosis of parent arteries could only be found in CAP group. Pathol ogical research showed that CAP mass could packed the aneurysms more densely tha n coils. Acute chemical damage of aneurysmal wall and inflammatory cell infiltra tion was prominently found in early stage after CAP embolization. Organization of thrombus inside aneurysms and formation of endothelial tissue over the orific es of aneurysmal necks could be found in both groups 2 months after embolization . But parts of coils might be exposed outside endothelial layer. Conclusions. EDC are still the most safe, efficient, and reliable instruments to embolize aneurysm. CAP should be improved further to solve the problem of stron g chemical corrosion and difficulty in control before it is widely used.

A ferrocene-mediated anti-interfering glucose biosensor based on glutin and cellulose acetate

A ferrocene-mediated glucose biosensor removing interference of ascorbic acid and uric acid was developed by coating of ferrocene, glutin and cellulose acetate on screen-printed gold electrode surface. The resuhs show that it can detect glucose sensitively in the presence of uric acid and ascorbic acid, and also suppress the leakage velocity of fcrrocene. Compared to the currents of the pretreated electrode, it decreases the current of uric acid and ascorbic acid by 99.4% and 98.8% at 400 mV, respectively, with a dynamic range of 0 - 30 mM for glucose, sensitivity of 30.73 nA/mM, response time of 10 s, and correlation coefficient of 0.998 8.

Surface Modifications of Cellulose Acetate Film for the Application of Face Shield

During the COVID-19 pandemic, personal protective equipment (PPE) has become crucial to protect humans from the transmission of the virus. The face shield is a simple and effective PPE to prevent the viral and bacterial contact. Since COVID-19 is known to be spread via respiratory droplets, the face shield has become increasingly important PPE. However, the common materials used in face shields are synthetic, environmentally unfriendly polymers, which cause an accumulation of plastic waste once disposed. Cellulose acetate (CA) can be used as an alternative for face shield films due to its ability to decompose safely in the environment;however, pristine CA cannot serve as an effective face shield due to its low hydrophobicity. In this research, the somewhat hydrophilic character of CA with a water contact angle of 55° is experimented on: hexamethyldisilazane (HMDS) is utilized to improve the hydrophobicity of CA up to a water contact angle of 77°. After the oxidization of the surface of CA via oxygen plasma, implementing HMDS shows a significant increase in hydrophobicity of the film.

LYOTROPIC AND THERMOTROPIC LIQUID CRYSTALL INE TRIALKYL CELLULOSES OBTAINED DIRECTLY FROM CELLULOSE ACETATE IN DIMETHYL SULFOXIDE

Highly substituted n-atkyl celluloses with sidechains 3 to 10 carbon atoms long have been prepared from cellulose acetate, sodium hydroxide and n-alkyl bromides with dimethyl sulfoxide as solvent. Synthetic conditions of n-alkyl celluloses were studied with respect to reaction temperature, time and yield. The molecular structure of the n-alkyl celluloses, which were obtained as white powders or as sticky, soft and birefringent solids at room temperature, was investigated by IR and NMR spectra and elemental analysis. The highly substituted n-alkyl celluloses all exhibited both therotropic and lyotropic liquid crystalline cholesteric phases in some non-polar solvents. The metting behavior and solubility of the n-alkyl celluloses were examined.

Synthesis and Characterization of a New Cellulose Acetate-Propionate Gel: Crosslinking Density Determination

Crosslinking is one of the most commonly reactions used to improve the physical properties of cellulose derivatives. Cellulose Acetate Propionate (CAP) is a commercial ester obtained as a cellulose derivative and it can be used as basis for the synthesis of crosslinked chains as described in this work. Typical used crosslinkers are di-functional compounds, such as dianhydrides or diisocyanate. The formation of polymeric 3D structures as described in this work occurs typically by the reaction of the linear chains bearing free OH groups with crosslinking agents such as dianhydrides. These reactions are used to make a very absorbent material, typically a gel. The syntheses were performed in homogeneous medium with acetate propionate in a very dry atmosphere by employing PMDA (Pyromellitic Dianhydride) and BTDA (3,3’, 4,4’ Benzophenone Tetracarboxylated Dianhydride) as crosslinking agents in a reflux system. TGA analysis has shown the different thermal stability of the gels when compared with CAP. Typical TGA curves have demonstrated the lower stability of the crosslinked chains when compared to CAP as consequence of esther linkages formed in the gels structures. The Mc, which is the value for the molar mass between crosslinkings points in 3D structure, was determined according to Flory-Rehner theory. This important parameter has demonstrated greater reactivity of PMDA in comparison with the BTDA in the reactions conditions’ employed in this work.

Gallic Acid-loaded Cellulose Acetate Electrospun Nanofibers: Thermal Properties, Mechanical Properties, and Drug Release Behavior

The gallic acid-loaded electrospun cellulose acetate fibers were successfully prepared. The fiber containing 2.5% gallic acid was smooth surface but observed drug flake on the surface of the fiber when increasing drug content. The thermal properties, mechanical properties and drug release behavior of the fibers were investigated comparing to the corres-ponding films.

Formulation development and characterization of cellulose acetate nitrate based propellants for improved insensitive munitions properties

Cellulose acetate nitrate(CAN) was used as an insensitive energetic binder to improve the insensitive munitions(IM) properties of gun propellants to replace the M1 propellant used in 105 mm artillery charges.CAN contains the energetic nitro groups found in nitrocellulose(NC),but also acetyl functionalities,which lowered the polymer's sensitivity to heat and shock,and therefore improved its IM properties relative to NC.The formulation,development and small-scale characterization testing of several CAN-based propellants were done.The formulations,using insensitive energetic solid fillers and high-nitrogen modifiers in place of nitramine were completed.The small scale characterization testing,such as closed bomb testing,small scale sensitivity,thermal stability,and chemical compatibility were done.The mechanical response of the propellants under high-rate uni-axial compression at,hot,cold,and ambient temperatures were also completed.Critical diameter testing,hot fragment conductive ignition(HFCI) tests were done to evaluate the propellants' responses to thermal and shock stimuli.Utilizing the propellant chemical composition,theoretical predictions of erosivity were completed.All the small scale test results were utilized to down-select the promising CAN based formulations for large scale demonstration testing such as the ballistic performance and fragment impact testing in the105 mm M67 artillery charge configurations.The test results completed in the small and large scale testing are discussed.

Enhanced Removal of Phosphates by the Adsorbent Consisting of Iron Oxide Loaded on Porous Chitosan/Cellulose Acetate Particle

The effective and economical removal of phosphates from aqueous solution, mostly applied in waste water treatment, is one of the significant issues globally. Removal of phosphates ions in aqueous solution was analysed by chitosan blended with cellulose acetate, and iron oxide loaded chitosan-cellulose acetate adsorbents. The adsorbents were made in the form of beads. Batch experiments were performed to investigate the performance of the beads under various conditions on phosphate adsorption. Contact time, effect of initial phosphate concentration, adsorbent dosage, pH and temperature were investigated. Zeta potential measurements were also undertaken. The results showed that the adsorption process was highly pH dependent. The adsorption kinetics data were modelled with the application of adsorption reaction models and adsorption diffusion models. The results revealed that the pseudo 2nd order model was the best fitting in all cases. The experimental data were tested with Langmuir and Freundlich isotherms. The equilibrium data were well fitted to the Langmuir isotherm model with a maximum adsorption capacity of 958 μg/g. The Freundlich isotherm model also had a close fit with a maximum adsorption of 233 μg/g, which was very close to the experimental maximum adsorption. The mechanism of adsorption followed two stages in which the first one was fast followed by a slower gradual stage. SEM images showed that the adsorbent was macroporous. Fourier Transform Infrared Red (FT-IR) Spectroscopy, X-ray Diffraction Spectroscopy (XRD) and X-ray photoelectron Spectroscopy (XPS) showed that the phosphate adsorption on the HFO-CS/CA beads was due to surface complexes, and mainly involved Nitrogen atoms. HFO loading also increased surface area.

Fabrication of Solvent-Resistant Nanofiltration Membrane via Interfacial Polymerization Based on Cellulose Acetate Membrane

Although a great progress has been achieved for the development of NF membranes and technologies and SRNF do show a great potential in the separation of organic components, an NF membrane with good separation performance and good resistance to organic solvents are urgently needed for a more complicated situation in practical. In this study, a kind of solvent-resistant nanofiltration (SRNF) membrane was fabricated via interfacial polymerization on a laboratory optimized cellulose acetate (CA) basic membrane. The effects of interfacial polymerization parameters, such as water phase concentration, immersed time in the water phase and in the organic phase, on the pure water flux and rejection rate of C-2R yellow dyestuffs were investigated. A highest dye rejection rate of 72.9% could be obtained by water phase solution containing 1% m-xylylenediamine (mXDA) and organic phase solution with 0.2% trimesoyl chloride (TMC) under immersed time in water phase of 6 minutes and in organic phase of 40 seconds. This membrane demonstrated better resistance to methyl alcohol compared to commercial membrane. This study may offer an avenue to develop a solvent-resistant nanofiltration membrane.