Bovine Serum Albumin Solution Research Articles

Simple model for the calculation of concentration and temperature dependent refractive index of different solutions

Simple analytical models for the calculation of concentration (c) and temperature (T) dependent refractive index i.e., n(c,T) values of the six solutions namely, three electrolyte (KCl, NaCl, and CaCl2), a polar (glucose), a non-polar (ethyl acetate), and a protein (bovine serum albumin) solutions have been proposed. The values of refractive index obtained using our proposed models have been compared with the corresponding values of the refractive index obtained using other reported models and the experimental values. A fairly good agreement between them has been obtained.

Bioinspired artificial synovial fluid for in vitro frictional behavior of bovine articular cartilage and auxiliary biomaterials

Synovial fluid is a non-Newtonian substance that lubricates the space between the diarthrodial joints produced by the synovial membrane. The properties pertaining to the rheology of the synovial fluid play a significant role in mimicking the frictional and wear behavior of articular cartilage as similar to native tissue. Most of the researchers used the bovine serum for conducting tribological studies. However, the bovine serum obtained from the different laboratories does not execute properties similar to the native synovial fluid. Hence, it is essential to develop synthetic synovial fluid. The researchers used immunoglobulins G (IgG) derived from human or animal serum to prepare synovial fluid. The average cost of IgG is approximately $10/mg. The current research proposed the bovine colostrum-derived IgG and glycerol to develop the artificial synovial fluid (ASF). Bovine colostrum comprises 42 to 90 mg/ml of IgG, which is inexpensive and easy availability. The foremost supplements for preparing ASF include sodium hyaluronate, bovine serum albumin, lecithin, and ringer solution. The composition of each element is adjusted to obtain the requisite rheological properties and compared the same with human synovial fluid from the literature. Rheological, wettability and tribological characterization were carried out to evaluate the performance of developed ASF. All the ASF samples exhibited good rheological properties with excellent hydrophilic behavior. The lower coefficient of friction (0.03 to 0.085) was observed for the cartilage-cartilage and meniscus-cartilage pair. The developed fluid exhibited admirable lubrication properties and was comparatively economical. Hence, the proposed ASF was a promising fluid for conducting in vitro tribological studies on articular cartilage and auxiliary biomaterials.

High dye separation performance of novel Cu‐BTC/PES MMMs with water‐stabilized Cu‐BTC nanoparticles

AbstractMetal–organic frameworks (MOFs), as porous materials, have been extensively applied in a variety of realms, but little of these has been reported used in sewage disposal field owing to its precariousness toward water. Herein, a novel mixed matrix membrane of polyethersulfone (PES) was synthesized using Cu‐BTC‐IPA, a hydrolytic resistance MOF modified with isopropanol (IPA), which exhibits high permeability and water stability. A significant increase in hydrophilicity of the membrane was found in the modified membranes compared with the pure membrane. The porosity measurement confirmed the increased efficiency of mass transfer in the modified membranes. An enhancement in membrane performance was observed by introducing the Cu‐BTC‐IPA filler into the PES matrix, with a remarkable increase (207%) in pure water flux observed compared to that of the pristine PES membrane (264.2 L m−2 h−1 bar−1), reaching 546.4 L m−2 h−1 bar−1. Meanwhile, it exhibited superior rejection of dyestuffs (98.4% for Congo red and 98.9% for Coomassie brilliant blue). In addition, the Cu‐BTC‐IPA/PES mixed matrix membrane demonstrated remarkable anti‐biofouling properties, as evidenced by its high flux recovery rates of bovine serum albumin (BSA) solutions. The consequences indicate that introducing stable MOF into mixed matrix membranes (MMMs) is extremely effective in improving membrane performance for sewage treatment.

Enhancing anti‐biofouling property by incorporating graphene oxide‐silver nanocomposite into polycaprolactone membrane for ultrafiltration application

AbstractBACKGROUNDThe control of biofouling is crucial in the membrane separation process. In the present study, graphene oxide‐silver (GO‐Ag) nanocomposite was fabricated and incorporated into polycaprolactone (PCL) membrane for the first time to increase its antibacterial properties and reduce its biofouling. Characterization of GO‐Ag nanocomposite was done by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier‐transform infrared (FTIR) spectroscopy. The PCL/GO‐Ag membranes were also characterized by XRD, attenuated total reflectance Fourier‐transform infrared (ATR‐FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), porosity determination, water contact angle measurement, and tensile test. Furthermore, pure water flux (PWF) and bovine serum albumin (BSA) rejection of the membranes were evaluated. Finally, the antibacterial activity of membranes was investigated by diffusion inhibition zone test and plate count of colony‐forming units.RESULTSThe results demonstrated that Ag nanoparticles were formed on the GO surfaces. In addition, membranes incorporated with the GO‐Ag nanocomposite were more hydrophilic, more porous, and more permeable to pure water while showing a lower protein rejection in the filtration of a BSA solution. Adding the GO‐Ag nanocomposite to the PCL membrane increased the inhibition effect against bacteria. The colony counting method confirmed that PCL/GO‐Ag membranes had higher antibacterial properties than the pure PCL membrane, and the PCL/1.8% GO‐Ag membrane represented the maximum antibacterial efficiency of 90% and 98% against P. aeruginosa and S. aureus, respectively.CONCLUSIONOverall, by the incorporation of GO‐Ag nanocomposite into the PCL membrane, PWF and antibacterial property were augmented, while protein rejection dropped. © 2023 Society of Chemical Industry.

Enhancing Polysulfone Mixed-Matrix Membranes with Amine-Functionalized Graphene Oxide for Air Dehumidification and Water Treatment.

Porous low-pressure membranes have been used as active membranes in water treatment and as support for thin-film composite membranes used in water desalination and gas separation applications. In this article, microfiltration polysulfone (PSf)mixed-matrix membranes (MMM) containing amine-functionalized graphene oxide (GO-NH2) were fabricated via a phase inversion process and characterized using XPS, SEM, AFM, DMA, XRD, and contact angle measurements. The effect of GO-NH2 concentration on membrane morphology, hydrophilicity, mechanical properties, and oil-water separation performance was analyzed. Significant enhancements in membrane hydrophilicity, porosity, mechanical properties, permeability, and selectivity were achieved at very low GO-NH2 concentrations (0.05-0.2 wt.%). In particular, the water permeability of the membrane containing 0.2 wt.% GO-NH2 was 92% higher than the pure PSf membrane, and the oil rejection reached 95.6% compared to 91.7% for the pure PSf membrane. The membrane stiffness was also increased by 98% compared to the pure PSf membrane. Importantly, the antifouling characteristics of the PSf-GO-NH2 MMMs were significantly improved. When filtering 100 ppm bovine serum albumin (BSA) solution, the PSf-GO-NH2 MMMs demonstrated a slower flux decline and an impressive flux recovery after washing. Notably, the control membrane showed a flux recovery of only 69%, while the membrane with 0.2 wt.% GO-NH2 demonstrated an exceptional flux recovery of 88%. Furthermore, the membranes exhibited enhanced humidity removal performance, with a permeance increase from 13,710 to 16,408. These results indicate that the PSf-GO-NH2 MMM is an excellent candidate for reliable oil-water separation and humidity control applications, with notable improvements in antifouling performance.

Technique for reducing the surgical porosity of small-diameter vascular grafts

High surgical porosity (SP) is one of the causes of significant blood loss, as well as hematoma formation. So, reducing the SP of small-diameter vascular grafts (VGs) is a crucial task.The objective of this work was to develop a technology for the formation of polycaprolactone (PCL)-based small-diameter VGs with a bioactive coating with reduced SP.Materials and methods. Porous VGs with an inner diameter of 3 mm were fabricated by electrospinning from 5% PCL solution with addition of 5–30% gelatin (PCL/G) on an NANON-01A unit (MECC CO, Japan). Bioactive coating was applied by sequential incubation of VGs in solutions of bovine serum albumin, heparin and platelet lysate with fixation in a glutaric aldehyde solution. The surface structure and mechanical properties of the samples were investigated. Functional properties of the bioactive VGs were evaluated in relation to their interaction with cell cultures in vitro.Results. It was found that introduction of gelatin into the working solution reduces SP from 30.4 ± 1.5 mL/(cm2 ·min) to 2.8 ± 0.5 ml/(cm2 ·min). It was shown that at a PCL/gelatin ratio of 9 : 1, the outer and inner sides of the bioactive VGs samples are characterized by surface uniformity (no defects), mechanical properties close to blood vessels of the same diameter (Young’s modulus 6.7 ± 2.1 MPa, tensile strength 26.7 ± 4.9 N and elongation to break 423 ± 80%) and ability to support adhesion and proliferation of human umbilical vein endothelial cell line, EA.hy926.Conclusion. Introduction of 10% gelatin content (by the polymer weight) into PCL solution reduces the SP of small-diameter VGs, leads to uniformity in their inner and outer surface, improvement in their mechanical properties without reducing their ability to support adhesion and proliferation of vascular endothelial cells.

Surface modification of a PVDF membrane by co‐grafting hydroxyl and zwitterionic polymers to enhance wettability and antifouling property

AbstractPolyvinylidene fluoride (PVDF) membranes have been widely applied in the separation of various organic matters owing to their excellent properties. However, they possess low wettability and undergo fouling because of the hydrophobic nature of PVDF. In this study, poly (2‐hydroxyethyl methacrylate) (PHEMA) and poly (sulfobetaine methacrylate) (PSBMA) were co‐introduced to modify the highly hydrophobic PVDF membrane surface via UV photo‐irradiation. Facile UV photo‐grafting was performed by irradiating the pristine PVDF membrane immersed in a PHEMA/PSBMA mixture solution with UV light for 5 min. The performance of the as‐prepared PHEMA/PSBMA‐grafted membrane was compared with that of membranes modified with solely PHEMA or PSBMA. The hydroxyl and zwitterionic groups of the grafted membranes enhanced wettability and increased flux. A tightly bound water layer was formed because of the enhanced wettability, significantly suppressing protein adsorption. The initial flux of bovine serum albumin (BSA) solution through the PHEMA/PSBMA‐grafted membrane was 2861 LMH, which was 3.1 times higher than that obtained by the pristine PVDF membrane. Furthermore, the flux decline of the modified membrane caused by BSA fouling was 49% lower than that of the pristine PVDF membrane. Finally, the PHEMA/PSBMA‐grafted PVDF membrane showed antifouling properties after three BSA filtration cycles.

Effectiveness of different CuO morphologies nanomaterials on the permeability, antifouling, and mechanical properties of PVDF/PVP/CuO ultrafiltration membrane for water treatment

The hydrophobic nature of Poly (vinylidene fluoride) (PVDF) is a significant barrier to use in ultrafiltration, resulting in fouling, flux decline, and reduced lifespan in water treatment. This study examines the effectiveness of different morphologies of CuO nanomaterials (NMs) (spherical, rod, plate, and flower), synthesized by the facile hydrothermal method, to modify PVDF membrane with PVP additive for improving the performance of water permeability and antifouling. Such membrane configurations with different morphologies of CuO NMs improved hydrophilicity with a maximum water flux of 222–263 L m−2h−1 compared to 195 L m−2h−1 for the bare membrane and exhibited excellent thermal and mechanical strengths. The characterization results exhibited that plate-like CuO NMs were dispersed uniformly in the membrane matrix, and their incorporation as a composite improved the membrane properties. From the antifouling test with the bovine serum albumin (BSA) solution, the membrane with plate-like CuO NMs had the highest flux recovery ratio (FRR) (∼91%) and the lowest irreversible fouling ratio (∼10%). The antifouling enhancement was due to less interaction between modified membranes and foulant. Further, the nanocomposite membrane showed excellent stability and negligible Cu2+ ion leaching. Overall, our findings provide a new strategy for developing inorganic nanocomposite PVDF membranes for water treatment.

Multi‐Band Polarization‐Independent Quasi‐Bound States in the Continuum Based on Tetramer‐Based Metasurfaces and Their Potential Application in Terahertz Microfluidic Biosensing

AbstractQuasi‐bound state in the continuum (quasi‐BIC) has drawn increasing attention in terahertz biosensing and filtering owing to an extremely narrow linewidth and ultra‐high quality factor. However, it is usually polarization‐sensitive due to broken structure or incidence symmetry and mainly holds for polarization‐dependent single or dual bands, which sets a limitation on practical applications. Here, this article proposes and experimentally demonstrates terahertz multi‐band polarization‐independent quasi‐BICs in tetramer‐based metasurfaces by using the laser etching method. Employing a tetramer cluster with C4v symmetry as the structural unit, which consists of four L‐type copper particles on a flexible and optically‐transparent substrate, the metasurfaces can support dual‐band or tri‐band polarization‐independent quasi‐BICs after performing collective perturbation, specific displacement, or both to the constituent particles. Furthermore, the metasurfaces are integrated with microfluidic channels to explore their potential application in terahertz biosensing. Experimental results indicate that when the concentration of bovine serum albumin solutions is below 4 mg mL−1, both resonance modes of the dual‐band terahertz microfluidic biosensor exhibit a sensitivity of ≈12 GHz mg−1 mL each, and the detection limits reach 0.17 mg mL−1. This work provides a general and simple strategy to construct metasurfaces supporting multi‐band polarization‐independent quasi‐BICs, which have promising applications in biosensing, filtering, and lasing.

Enhancing the Antimicrobial and Anti-biofouling Properties of Polyamide Composite Membrane Grafted with Polyhexamethylene Guanidine (PHMG)

In this work, a thin-film composite polyamide membrane with antimicrobial polyhexamethylene guanidine (PHMG) was fabricated by the combination of photo-induced and chemical grafting to enhance the antifouling and anti-biofouling properties of the membrane. The surface properties of the membrane were evaluated using field-emission scanning electron microscopy (FE-SEM) images, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), water contact angle (WCA) values, and antimicrobial activity of the membrane. The membrane separation performance was evaluated by the flux and the ability to retain Ca2+ ions in water. The antifouling and anti-biofouling properties were evaluated by the maintained flux ratios after 9 hour-filtration of humic acid and bovine serum albumin (BSA) solutions. The results showed that the grafted membrane’s surface became tighter (the retention increased from 97.3% to 98.6%), and no bacteria were observed on the surface of the grafted membrane. Meanwhile, the anti-fouling and anti-biofouling properties were also improved compared to the original membrane.

Influence of laser radiation of a surgical laser on the structure of bovine serum albumin molecules in vitro

The influence of laser radiation of a surgical laser on the physicochemical properties of bovine serum albumin molecules was studied. After exposure to laser radiation, the optical density of protein solutions increases, the fluorescence intensity decreases, a significant decrease of the intensity of the a-helix band on the Raman spectrum is observed and the refractive index of protein solution did not significantly change. However, the viscosity increased, and the pseudoplasticity of aqueous solutions of albumin decreased. There was no massive damage to the protein polypeptide chain, on the contrary, intensive aggregation was observed. Thus, in a bovine serum albumin solution subjected to contact action of laser radiation, the processes of partial denaturation and aggregation prevail, aromatic amino acid residues of the protein are damaged to a lesser extent, and fragmentation of albumin molecules is not observed.

Antifouling polymeric nanocomposite membrane based on interfacial polymerization of polyamide enhanced with green TiO2nanoparticles for water desalination

In the present investigation, the preparation and characterization of polyamide/TiO2as thin film nanocomposites (TFN) for brackish water desalination was investigated. TiO2nanoparticles (NPs) were synthesized by a green method using thyme plant extract as a reducing and capping agent. The TiO2NPs was successfully prepared in pure crystalline anatase phase with 15 nm size, and −33.1 mV zeta potential. The antimicrobial tests confirmed the antimicrobial activity of TiO2against gram-positive and gram-negative bacteria. In addition, TiO2NPs showed a good photocatalytic activity in degradation of methylene blue dye. TFN based on interfacial polymerization was enhanced by embedding 5% of the greenly synthesized TiO2NPs within the polyamide thin film active layer. The incorporation of TiO2NPs was confirmed by SEM, atomic force microscope (AFM), surface wettability, and FTIR. Membranes performance was investigated based on flux, salt rejection and fouling resistance. The antifouling was examined using bovine serum albumin (BSA) as protein fouling by dead-end cell filtration system at 2 bar. The results showed the TFN increased in water flux by 40.9% and a slight decrease in NaCl rejection (6.3%) was observed, with enhancement in antifouling properties. The flux recovery rate of the modified TFN membranes after fouling with BSA solution was enhanced by 21.5% (from 61.7% for TFC to 83.2% for TFN). Also, they demonstrated remarkable anti-biofouling behavior against both bacterial strains.

Preparation and dye separation performance of ZIF-67/mesoporous silica ceramic nanofiltration membrane by liquid phase epitaxy (LPE) growth method

Ceramic membrane plays an important role in separation process with advantages of high thermal and chemical resistances, but its applications on the nanofiltration are restricted because of the limitation of pore size. In this study, a commercial tubular ceramic membrane with pore diameter of 0.1 μm was firstly coated with mesoporous silica substrates, in which ZIF-67 nanocrystals were generated layer-by-layer inside the mesochannels via liquid phase epitaxy growth method. The open pore size of ceramic membrane can be precisely controlled by increasing the growth cycles of ZIF-67 nanocrystals. The influence of preparation conditions on the dye separation was investigated, including growth cycles, precursor concentration, and molar ratio of Co2+/2-methylimidazole (Co2+/Hmim). Under the optimized conditions, the rejection of methylene blue, methyl orange, chromium black T, rhodamine B, acid fuchsin, and Congo red were in the range of 92–99 % with membrane fluxes of 0.45–0.73 L m−2 h−1. Bovine serum albumin solution was used to evaluate the anti-fouling abilities of the ceramic membrane. The flux recovery ratio, which was calculated according to the ratio between the water permeance after washing and before filtration, was 52.3 % with the flux decline rate of 66.3 %.

Influence of aluminum and iron chlorides on the parameters of zigzag patterns on films dried from BSA solutions

The relationships between the structural and aggregational state of bovine serum albumin (BSA) and the specific length and total number of zigzag pattern segments of the film textures formed upon drying biopolymer solutions with aluminum and iron chlorides have been shown. To obtain films, saline solutions of BSA were dried in a glass cuvette under thermostatically controlled conditions. It is shown that the formation of zigzag structures is sensitive to the influence of aluminum chlorides Al3+ and iron chlorides Fe3+ and depend on the concentration of AlCl3 and FeCl3. This may be due to a change in the charge and size of BSA particles and due to a change in conformation or a violation of the structure of BSA. These factors, in turn, affect the hydration of the solution components and the structural state of free water in solution, which presumably also affects the formation of zigzag structures. It is established that the analysis of the specific length and the number of segments of zigzag patterns makes it possible to evaluate changes in the state of biopolymers in the initial solution during structural changes and aggregation.

RENAL4: Indoxyl Sulfate Removal by NORIT RO Carbon and the Adsorba 300 Hemoperfusion Column

Purpose: Indoxyl sulfate is a protein-bound uremic toxin typically cleared by the kidneys. In end-stage renal disease (ESRD) it accumulates, contributing to vascular disease and possible early mortality. A number of novel charcoal-based adsorbents remove indoxyl sulfate, but the FDA-approved Adsorba 300 column has never been tested for this. Indoxyl sulfate removal using a currently approved medical device would be of great practical value. Methods: We studied indoxyl sulfate removal from albumin solutions. We first used a charcoal column designed in our lab and a commercially available Norit RO 0.8 based charcoal. Norit RO 0.8 resembles the charcoal in the Adsorba 300. We tested bovine and human serum albumin solutions (BSA and HSA respectively). Indoxyl sulfate was measured by mass spectrometry. After this proof of concept, we used Adsorba 300 columns. Results: We found that adsorbent columns made with Norit RO 0.8 can remove indoxyl sulfate from BSA and HSA solutions. With the Adsorba 300 column indoxyl sulfate concentration fell below the limit of detection within 15 minutes from a BSA solution. Summary: The clinically available Adsorba 300 hemoperfusion column can remove the albumin bound uremic toxin indoxyl sulfate in vitro. This toxin is not dialyzable. This detoxification option may improve treatment of ESRD. In vivo testing should be considered.

Graphene oxide/chitosan doped polysulfone membrane for the treatment of industrial wastewater

Rapid urbanization and industrialization have created tremendous stress on fresh water sources. Moreover, discharge of industrial wastewater has left public health and environment under high potential risks. In this paper, chitosan-functionalized graphene oxide (GO-CH) was synthesized and incorporated into polysulfone (Psf) ultrafiltration membranes. The concentration of the nanocomposite and the ratio of GO to CH in the nanocomposite were varied to produce different GO-CH doped polysulfone membranes. The effect of GO-CH addition on the morphology and membrane performance was studied through water contact angle, scanning electron microscopy, atomic force microscopy, porosity, pore size, and permeation measurements as well as rejection and antifouling tests, while produced GO-CH nanocomposite was characterized using FTIR and XRD analyses. The GO-CH/Psf membrane exhibited higher water flux, bovine serum albumin (BSA) rejection rate, and water flux recovery ratio, and lower BSA solution flux attenuation rate than pristine Psf membrane. GO-CH/Psf membrane containing 0.085 wt% nanocomposite with GO to CH ratio of 1 to 0.01 had an improved permeate flux of 136%. Maintaining the same GO-CH composition of 0.085 wt% and changing GO to CH ratio to 1:1 resulted in better hydrophilicity (contact angle 68°) and increased reversible fouling from 23 to 33%. The best membrane was further tested with real industrial wastewater obtained from a GTL plant in Qatar showed 28% improvement in COD removal.

Improvement of the antifouling and antibacterial properties of polyethersulfone membrane by incorporating the natural additives collagen and green tea

This study focuses on the fabrication of low-fouling polyethersulfone ultrafiltration (PES UF) membranes using collagen (COL) and polyphenon 60 from green tea (PGT) as additives. The casting solution was prepared by dissolving COL and PGT in PES solution with N-methyl-2-pyrrolidone as solvent. A series of characterizations and performance examinations, including scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX) mapping, Fourier transform infrared spectroscopy (FTIR), contact angle (CA) measurement, pure water flux (PWF), porosity, antifouling test using bovine serum albumin (BSA) and humic acid (HA) solution, antibacterial test using E. coli and S. mutans, were conducted. The addition of COL and PGT not only significantly increased PWF, water uptake, porosity, and hydrophilicity but also increased solute rejection and flux recovery. The membrane prepared with the addition of COL (1 wt%) and PGT (3 wt%) demonstrated PWF of 353.9 L/m2. h, water uptake of 238.8%, porosity of 75.1%, CA of 36.9°, and solute rejection of 98.5%. Further, the flux recovery reached 85.08% and 78.78% after anti fouling examination using BSA and HA solutions, respectively. The COL/PGT/PES membrane also demonstrated superior dynamic antibacterial filtration with 93.5% bacteria removal of E. coli and highly efficient antibacterial activity above ∼98% against both E. coli and S. mutans. Thus, the COL/PGT/PES membrane exhibited significant antifouling and antibacterial properties and better performance than the nascent PES UF membrane.

Water-Soluble Ionic Metal-Organic Polyhedra as a Versatile Platform for Enzyme Bio-immobilization.

Metal-organic polyhedra (MOPs) can act as elementary structural units for the design of modular porous materials; however, their association with biological systems remains greatly restricted by their typically low stabilities and solubilities in water. Herein, we describe the preparation of novel MOPs bearing either anionic or cationic groups and exhibiting a high affinity for proteins. Simple mixing of the protein bovine serum albumin (BSA) and ionic MOP aqueous solutions resulted in the spontaneous formation of MOP-protein assemblies, in a colloidal state or as solid precipitates depending on the initial mixing ratio. The versatility of the method was further illustrated using two enzymes, catalase and cytochrome c, with different sizes and isoelectric points (pI's) below and above 7. This mode of assembly led to the high retention of catalytic activity and enabled recyclability. Furthermore, the co-immobilization of cytochrome c with highly charged MOPs resulted in a substantial 44-fold increase of its catalytic activity.

Detection of C-Reactive Protein Using a Flexible Biosensor with Improved Bending Life

It is well known that regular monitoring of C-reactive protein is beneficial for the self-management of chronic diseases. Herein, a novel tattoo biosensor for regular measurement of C-reactive protein is presented. An innovative approach is presented to boost the life cycle of flexible biosensors in bending tests. Carbon nanotubes were deposited on the biosensor’s surface using electrophoretic methods. To assess suspension stability, a zeta potential measurement was performed. Optimized parameters of the electrophoretic procedure were evaluated through scanning electron microscopy imaging. This study shows that carbon nanotube coating increases the biosensor life-cycle by ten times (from 10 to 160 cycles). Using atomic force microscopy, the immobilization of a recognition element (aptamer) on the biosensor’s surface was verified. Furthermore, the biosensor’s performance was characterized using two electrochemical methods (cyclic voltammetry and impedance spectroscopy). The biosensor achieved a detection range of 0.02 − 0.8 ng ml−1. The sensor selectivity was examined with a solution of bovine serum albumin, immunoglobin E, interleukin 6, and tumor necrosis factor α. Finally, we carried out a test with the biosensor on spiked human serum samples to confirm that our proposed flexible biosensor can successfully monitor C-reactive protein levels in a range of clinical samples.

Magnetic field assisted process for preparing anti-biofouling PVDF membranes incorporated by hydrophilic magnetic palygorskite

Membrane technology can realize wastewater recycling in industry, but its efficiency is threatened by fouling. In this study, magnetic palygorskite (m-Pal) nanofibers were obtained by anchoring Fe3O4 nanoparticles onto the surface of palygorskite. Then, composite membranes composed of poly(vinylidene fluoride) (PVDF) and m-Pal were prepared during a magnetic field assisted phase inversion process. The m-Pal can be elevated to the membrane surface due to magnetic force, thus adjusting membrane performance. The PVDF/m-Pal composite membrane prepared with magnetic field displayed higher water flux and better hydrophilicity than that of pristine PVDF membrane. The water flux can be increased to 343.2 L·m−2·h−1·bar−1, and water contact angle decreases to 71.8° with the addition of 7% m-Pal. Moreover, the anti-fouling and easy-cleaning performance of the composite membrane was demonstrated in bovine serum albumin (BSA) solution separation, with BSA flux and flux recovery ratio increased by 41.3% and 155.4%, respectively, compared with the control PVDF membrane.