Immobilization Method Research Articles

Image Sensing of Gaseous Acetone Using Secondary Alcohol Dehydrogenase-Immobilized Mesh for Exhaled Air.

Human-borne acetone is a potent marker of lipid metabolism. Here, an enzyme immobilization method for secondary alcohol dehydrogenase (S-ADH), which is suitable for highly sensitive and selective biosensing of acetone, was developed, and then its applicability was demonstrated for spatiotemporal imaging of concentration distribution. After various investigations, S-ADH-immobilized meshes could be prepared with less than 5% variation by cross-linking S-ADH with glutaraldehyde on a cotton mesh at 40 °C for 15 min. Furthermore, high activity was obtained by adjusting the concentration of the coenzyme nicotinamide adenine dinucleotide (NADH) solution added to the S-ADH-immobilized mesh to 500 μM and the solvent to a potassium phosphate buffer solution at pH 6.5. The gas imaging system using the S-ADH-immobilized mesh was able to image the decrease in NADH fluorescence (ex 340 nm, fl 490 nm) caused by the catalytic reaction of S-ADH and the acetone distribution in the concentration range of 0.1-10 ppm-v, including the breath concentration of healthy people at rest. The exhaled breath of two healthy subjects at 6 h of fasting was quantified as 377 and 673 ppb-v, which were consistent with the values quantified by gas chromatography-mass spectrometry.

Phenol Removal through Horseradish Peroxidase Immobilization on Ultrafiltration Membranes: Comparative Analysis of Immobilization Methods and Fouling Patterns

This research investigates the removal of phenol using pure peroxidase from horseradish grade I in conjunction with a dead-end ultrafiltration membrane. Various horseradish peroxidase (HRP) immobilization techniques— physical adsorption, covalent bonding, and cross-linking with glutaraldehyde—were applied to a regenerated cellulose (RC) membrane with a surface area of 44 m2 and a molecular weight cut-off of 30 kDa. The investigation examined factors influencing phenol removal, including phenol concentration, membrane fouling, and the reusability of immobilized enzymes. Results indicated that covalent bonding was the most suitable enzyme immobilization technique, achieving a remarkable 90.1% immobilization yield. Phenol removal efficiency reached 100% at 30 min under specific conditions: phenol concentration of 1 mg/L, pH 6.0, hydrogen peroxide concentration of 0.5 mM, and operating pressure set at 3 psig, with temperature maintained at 28 ± 3 °C. Membrane fouling resulted in a decrease in flux. The performance of fouling models was found to be influenced by phenol concentration, with the Cake Formation Model (CFM) proving most effective at low concentrations, while the Complete Pore Blocking Model (CBM) emerged as more suitable at higher concentrations. The immobilized enzyme exhibited reusability for five cycles, maintaining a phenol removal efficiency exceeding 50%. These findings contribute to understanding the enzymatic phenol removal process and the use of appropriate enzyme immobilization techniques for the effective and sustainable treatment of phenol-contaminated water.

Poprawa zdolności sorpcyjnej i zastosowania biosorbentu poprzez immobilizację

The water contamination by toxic metal ions is a worldwide environmental problem. High concentrations are hazardous for all living organisms, causing many disorders and diseases and ecological damages to the surroundings. Biosorption is an innovative technology that employs inactive and dead biomass (bacteria, fungi, algae, biowaste) for the recovery of metals from aqueous solutions. Sulphate-reducing bacteria utilization is one of the options how to prepare applicable sorbent which removes metal ions from water. This material is created as a consequence of bacteria metabolism in anaerobic environment. The use of freely suspended biomass is often impractical and has some disadvantages. In contrast to this, application of immobilized biomass shows more benefits including increased mechanical strength, resistance to chemical environment, easy separation of cells and effluents, high biomass performance and repeated use in many adsorption/desorption cycles. Cell entrapment is the most widely used method for immobilization. In this technique, the cells are enclosed in a polymeric matrix which is porous enough to allow diffusion of substrate to the cells. The aim of this work was to examine and compare the sorption ability of biogenic iron sulphides created by sulphate-reducing bacteria in “free” and “entrapped” form. Precipitates were synthesized in reagent bottles with bacteria culture and growth media Postgate C, at 30 °C during 60 days, subsequently dried and analysed. Prepared samples were immobilized using sodium alginate. Sorption of cadmium from model solutions was realized in 100 ml Erlenmeyer flasks, with sorbent dose 1 g/l, during 24 hours. During experiments, the samples showed a satisfying stability and maximum adsorption capacity achieved 38 mg/g. The results refer to good sorption properties of immobilized samples and their potential for further practical use.

Immobilised Inulinase from Aspergillus niger for Fructose Syrup Production: An Optimisation Model.

Fructose is a carbohydrate with essential applications in the food industry, mainly due to its high sweetness and low cost. The present investigation focused on optimising fructose production from commercial inulin using the enzymatic immobilisation method and applying the response surface methodology in a 12-run central composite design. The independent variables evaluated were the pH (-) and temperature (°C). The substrate consisted of a commercial inulin solution at a concentration of 1 g/L, while the catalyst consisted of the enzyme inulinase from Aspergillus niger (EC 232-802-3), immobilised in 2% m/v sodium alginate. A stirred vessel reactor was used for 90 min at 120 rpm, and quantification of reducing sugars was determined using DNS colorimetric and UV-Vis spectrophotometric methods at a 540 nm wavelength. After applying the response surface methodology, it was determined that the catalytic activity using the immobilisation method allows for a maximum total productivity of 16.4 mg/h under pH and temperature of 3.9 and 37 °C, respectively, with an efficiency of 96.4%. The immobilised enzymes' reusability and stability compared to free enzymes were evaluated, obtaining activity up to the fifth reuse cycle and showing significant advantages over the free catalyst.

Characterisation of a microelectrochemical biosensor for real-time detection of brain extracellular d-serine

A modified development protocol and concomitant characterisation of a first generation biosensor for the detection of brain extracellular d-serine is reported. Functional parameters important for neurochemical monitoring, including sensor sensitivity, O2 interference, selectivity, shelf-life and biocompatibility were examined. Construction and development involved the enzyme d-amino acid oxidase (DAAO), utilising a dip-coating immobilisation method employing a new extended drying approach. The resultant Pt-based polymer enzyme composite sensor achieved high sensitivity to d-serine (0.76 ± 0.04 nA mm−2. μM−1) and a low μM limit of detection (0.33 ± 0.02 μM). The in-vitro response time was within the solution stirring time, suggesting potential sub-second in-vivo response characteristics. Oxygen interference studies demonstrated a 1 % reduction in current at 50 μM O2 when compared to atmospheric O2 levels (200 μM), indicating that the sensor can be used for reliable neurochemical monitoring of d-serine, free from changes in current associated with physiological O2 fluctuations. Potential interference signals generated by the principal electroactive analytes present in the brain were minimised by using a permselective layer of poly(o-phenylenediamine), and although several d-amino acids are possible substrates for DAAO, their physiologically relevant signals were small relative to that for d-serine. Additionally, changing both temperature and pH over possible in vivo ranges (34–40 °C and 7.2–7.6 respectively) resulted in no significant effect on performance. Finally, the biosensor was implanted in the striatum of freely moving rats and used to monitor physiological changes in d-serine over a two-week period.

Hydrolysis of Casein by Pepsin Immobilized on Heterofunctional Supports to Produce Antioxidant Peptides.

A study was carried out on the immobilization of pepsin in activated carbon functionalized by different techniques (glutaraldehyde, genipin, and metallization) aiming at its application in obtaining bioactive peptides through casein hydrolysis. Studies of the immobilized derivatives were carried out in addition to the evaluation of the antioxidant potential of the peptides. Among the pH range studied, pH 3.0 was selected due to the higher activity of the derivatives at this pH. The support modification by metallization was the method with the best results, providing a 121% increase in enzymatic activity compared to other immobilization methods. In addition, this derivative provided activity closer to the soluble enzyme activity (3.30 U) and better storage stability, and allows reuse for more than 8 cycles. In turn, the peptides from casein hydrolysis showed potential as antioxidant agents, with a DPPH radical scavenging activity higher than 70%, maximum protection against β-carotene oxidation close to 70%, and a maximum reducing power of Fe(III) into Fe(II) of 400 uM by the FRAP assay. The results showed that the new techniques for modification of activated carbon can be a promising approach for pepsin immobilization.

Oriented immobilization of nanobodies using SpyCatcher/SpyTag significantly enhances the capacity of affinity chromatography

The use of nanobodies (Nbs) in affinity chromatography for biomacromolecule purification is gaining popularity. However, high-performance Nb-based affinity resins are not readily available, mainly due to the lack of suitable immobilization methods. In this study, we explored an autocatalytic coupling strategy based on the SpyCatcher/SpyTag chemistry to achieve oriented immobilization of Nb ligands. To facilitate this approach, a variant cSpyCatcher003 (cSC003) was coupled onto agarose microspheres, providing a specific attachment site for SpyTagged nanobody ligands. The cSC003 easily purified from Escherichia coli through a two-step procedure, exhibits exceptional alkali resistance and structural recovery capability, highlighting its robustness as a linker in the coupling strategy. To validate the effectiveness of cSC003-derivatized support, we employed VHSA, a nanobody against human serum albumin (HSA), as the model ligand. Notably, the immobilization of SpyTagged VHSA onto the cSC003-derivatized support was achieved with a coupling efficiency of 90 %, significantly higher than that of traditional thiol-based coupling method. This improvement directly correlated to the preservation of the native conformation of nanobodies during the coupling process. In addition, the Spy-immobilized resin demonstrated better performance in the binding capacity, with a 3-fold improvement in capture efficiency, underscoring the advantages of the Spy immobilization strategy for oriented immobilization of VHSA ligands. Moreover, online purification and immobilization of SpyTagged VHSA from crude bacterial lysate was achieved using the cSC003-derivatized support. The resulting resin exhibited high binding specificity towards HSA, yielding a purity above 95 % directly from human serum, and maintained good stability throughout multiple purification cycles. These findings highlight the potential of the Spy immobilization strategy for developing Nb-based affinity chromatographic materials, with significant implications for biopharmaceutical downstream processes.

Ionic liquid functionalized magnetic polydopamine enhancing enzyme stability and catalytic efficiency for water pollutant treatment

Laccase has received widespread attention in pollutant degradation, but the current challenges in its poor stability, easy inactivation, and difficult recovery have seriously affected the application. The enzyme immobilization technology is a crucial approach to enhance the stability, recoverability, and other valuable properties to improve the effectiveness of biocatalysts. In this study, a polydopamine coating Fe3O4 nanoparticle was modified with an ionic liquid, which can be used for laccase immobilization. The incorporation of polydopamine provided a biocompatible and reactive coating for nanoparticles, while the presence of ionic liquids ensured that enzyme molecules were positioned away from the carrier surface, which facilitated the stabilization of the spatial structure of the enzyme and the retention of its activity. The immobilized laccase exhibited a broad pH and temperature and satisfactory stability. The activity of immobilized laccase remained at approximately 80 % of its activity even after incubation at 50 ℃, and over 65 % activity at storage for 30 days, which is 1.6 times and 2.9 times higher than the free laccase, respectively. The biocatalytic demonstrated excellent removal of phenolic contaminants, achieving removal efficiencies of approximately 97 % for 2,4-dichlorophenol. The remarkable magnetic response greatly facilitates the collection and subsequent reuse of the biocatalyst up to six times while still maintaining a relative removal efficiency of over 70 % for 2,4-dichlorophenol. Furthermore, the biocatalytic also exhibited excellent removal efficiency for Bisphenol A and phenol, which were 1.5 and 1.4 times more effective than the free laccase. The immobilization method provided in this work offers new ideas for the development and efficient biological enzyme preparation for industrial wastewater treatment.

Flexible Ag-AgCl/TiO2/cellulose biocomposite film for solar photocatalytic degradation of VOCs

Photocatalyst immobilization on biopolymers presents a promising avenue for air purification, yet achieving efficient immobilization and purification methods remains a challenge. In this study, we develop a novel, straightforward sequential coating technique to fabricate cellulose film embedded with uniformly dispersed TiO2 submicrospheres and Ag-AgCl nanoparticles (NPs), tailored for effective indoor air purification under sunlight exposure. The obtained Ag-AgCl/TiO2/cellulose film exhibit remarkable photocatalytic prowess in degrading various volatile organic compounds (VOCs, including ethanol, 1-propanol, 1-butanol, propylamine, and propanethiol) under simulated sunlight, owing to the enhanced separation of charge carriers facilitated by the presence of plasmonic Ag-AgCl NPs. Notably, the nature of the functional groups and the carbon atom count within the VOCs molecular structures exert significant influence on the overall photocatalytic performance. Furthermore, our investigation into the reusability of this biocomposite film confirms its durability, particularly in mineralizing alcoholic compounds during VOC oxidization, and the deactivation primarily occurs with VOCs containing heteroatoms that can be residual on biocomposite surface. This study represents a significant step towards practical applications of biocomposite films with efficient photocatalytic activities for real-world air purification and environmental remediation.

EVALUATION OF IMMERSION IN EMULSIFIED ISOFLURANE OR PROPOFOL AS PART OF A TWO-STEP EUTHANASIA PROTOCOL IN MARBLED CRAYFISH (PROCAMBARUS VIRGINALIS).

The marbled crayfish (Procambarus virginalis) is a parthenogenetic invasive species across much of the world, and when found, euthanasia is often recommended to reduce spread to naïve ecosystems. Euthanasia recommendations in crustaceans includes a two-step method: first to produce nonresponsiveness and then to destroy central nervous tissue. Minimal data exist on adequate anesthetic or immobilization methods for crayfish. A population of 90 marbled crayfish was scheduled for euthanasia due to invasive species concerns. The population was divided into six treatment groups to evaluate whether immersion in emulsified isoflurane or propofol solutions could produce nonresponsiveness. Each group was exposed to one of six treatments for 1 h: isoflurane emulsified at 0.1%, 0.5%, 2%, 5%, and 15% or propofol at 10 mg/L and then increased to 100 mg/L. Crayfish from all treatment groups were moved to nonmedicated water after completion of 1 h and observed for an additional 4 h. All crayfish treated with isoflurane showed lack of a righting reflex at 5 min and loss of movement after 30 min. By 240 min (4 h), none of the crayfish from the isoflurane treatment groups regained movement. None of the crayfish in the propofol treatment achieved loss of reflexes or responsiveness, and all remained normal upon return to nonmedicated water. Isoflurane emulsified in water produces nonresponsiveness that is appropriate for the first step of euthanasia, while propofol was insufficient at these treatment doses.

A graphene oxide-assisted protein immobilization paper-tip immunosensor with smartphone and naked eye readout for the detection of okadaic acid

BackgroundOkadaic acid (OA), as a diarrhetic shellfish poisoning, can increase the risk of acute carcinogenic or teratogenic effects for the ingestion of OA contaminated shellfish. At present, much effort has been made to graft immunoassay onto a paper substrate to make paper-based sensors for rapid and simple detection of shellfish toxin. However, the complicated washing steps and low protein fixation efficiency on the paper substrate need to be further addressed. ResultsA novel paper-tip immunosensor for detecting OA was developed combined with smartphone and naked eye readout. The trapezoid paper tip was consisted of quantitative and qualitative detection zones. To improve the OA antigen immobilization efficiency on the paper substrate, graphene oxide (GO)-assisted protein immobilization method was introduced. Meanwhile, Au nanoparticles composite probe combined with the lateral flow washing was developed to simplify the washing step. The OA antigen-immobilized zone, as the detection zone Ⅰ, was used for quantitative assay by smartphone imaging. The paper-tip front, as the detection zone Ⅱ, which could qualitatively differentiate OA pollution level within 45 min using the naked eye. The competitive immunoassay on the paper tip exhibited a wide linear range for detecting OA (0.02–50 ng∙mL−1) with low detection limit of 0.02 ng∙mL−1. The recovery of OA in spiked shellfish samples was in the range of 90.3 %–113.%. SignificanceThese results demonstrated that the proposed paper-tip immunosensor could provide a simple, low-cost and high-sensitivity test for OA detection without the need for additional large-scale equipment or expertise. We anticipate that this paper-tip immunosensor will be a flexible and versatile tool for on-site detecting the pollution of marine products.

One‐pot immobilization of formate dehydrogenase on silica nanoparticles based on catechol chemistry with or without polyethyleneimine

AbstractConverting carbon dioxide into formic acid with formate dehydrogenase (FDH) as a catalyst is a gentle and eco‐friendly process that not only conserves energy and reduces emissions but transforms waste into valuable resource. Enzyme immobilization is a common strategy for improving the stability and recyclability of enzyme, however, the procedures are usually complicated that include surface modification and binding reactions in order to form reliable linkages. Co‐deposition of polydopamine (PDA) with polyethyleneimine (PEI) is a popular surface modification approach in versatile fields, but their co‐deposition with enzymes is rarely reported. Herein, one‐pot immobilization of FDH on SiO2 nanoparticles based on catechol chemistry was attempted for the first time with or without PEI, and the resultant immobilized enzymes, FDH/PDA/PEI‐SiO2 and FDH/PDA‐SiO2, were characterized, and the effects of the composition and deposition conditions on the catalytic performance were investigated. FDH/PDA‐SiO2 exhibited a higher apparent specific activity than FDH/PDA/PEI‐SiO2, which was separately 0.167 and 0.136 mM/h/mg. The activity recovery rate was 464% and 378% of that of free enzyme. After 5 cycles, their relative activity was 82.3% and 87.4%. This research is significant in presenting a simple and high‐efficient one‐pot immobilization method that can be extended to other kinds of enzymes.

Enhancing microbial fuel cell performance through microbial immobilization.

Bio-electrochemical Systems (BES), particularly Microbial Fuel Cells (MFC), have emerged as promising technologies in environmental biotechnology. This study focused on optimizing the anode bacterial culture immobilization process to enhance BES performance. The investigation combines and modifies two key immobilization methods: covalent bonding with glutaraldehyde and inclusion in a chitosan gel in order to meet the criteria andrequirements of the bio-anodes in MFC. The performance of MFCs with immobilized and suspended cultures was compared in parallel experiments. Both types showed similar substrate utilization dynamics with slight advantage of the immobilized bio-anode considering thelowerconcentration of biomass. The immobilized MFC exhibited higher power generation and metabolic activity, as well. Probably, this is due to improved anodic respiration and higher coulombic efficiency of the reactor. Analysis of organic acids content supported this conclusion showing significant inhibition of the fermentation products production in the MFC reactor with immobilized anode culture.

Highly-Sensitive Polymer Optical Fiber SPR Sensor for Fast Immunoassay

A new type of human immunoglobulin G (IgG) sensors based on the surface plasmon resonance (SPR) in the low refractive index (RI) plastic optical fiber (POF) and an antibody immobilization method is presented. A 50-nm-thick gold film was formed on the polished D-shaped fiber surface by magnetron sputtering. The RI response of the POF sensor is 30 049.61 nm/RIU, which is 26.5 times higher than that of single mode fiber (SMF) SPR sensors. The proposed SPR biosensor can be developed by simple and rapid modification of the gold film with 11-mercapto undecanoic acid (MUA). Upon immobilization of the goat anti-human IgG antibody, the resonance wavelength shifts by 11.2 nm. The sensor can be used to specifically detect and quantify the human IgG at concentrations down to 245.4 ng/mL with the sensitivity of 1.327 7 nm per µg/mL, which offers an enhancement of 12.5-fold compared to that of the conventional SMF based SPR sensors. The proposed device may find the potential applications in the case of use at the point of care.

Temporary immobilization methods for closed low-energy ankle fracture-dislocations: comparative analysis of a retrospective cohort.

Ankle fracture-dislocations (AFD) often necessitate staged management involving temporary external fixation (EF) due to mechanical instability or blistering. However, limited literature exists on the optimal temporary immobilization method for low-energy closed AFD. This study compared baseline patient and fracture characteristics, along with clinical and radiological outcomes between AFD initially immobilized with EF versus splinting. A retrospective cohort study was conducted involving patients with AFD temporarily immobilized using EF or splinting, followed by definitive open reduction and internal fixation. Quality of reduction (QOR) was assessed for each patient post-initial immobilization and after the definitive surgery. The study encompassed 194 patients: 138 treated with a splint (71.1%) and 56 (28.9%) with EF. Secondary loss of reduction had occurred in three patients who were splinted (2.2%). The mean ages in the EF and splint groups were 63.2 and 56.1years, respectively (p = 0.01). Posterior malleolus fracture (PMF) and blisters were more prevalent in EF patients (69.6% vs. 43.5% for PMF and 76.8% vs. 20.3% for blisters, respectively; p = 0.05 and p < 0.01). Postoperative complication rates were 8.9% for EF versus 10.9% for splinting (p = 0.69). Satisfactory final QOR was attained in 79.8% of patients treated with a splint versus 64.3% with EF (p = 0.02). Patients immobilized by EF presented with poorer baseline characteristics and had more unstable injuries. Nevertheless, postoperative complication rates were comparable. Thus, EF appears to be a valuable tool for standardizing outcomes in AFD patients with a less favorable prognosis.

Predictive Modeling for Functional Outcomes After All-Inside Arthroscopic Anterior Talofibular Ligament Repair of Chronic Ankle Instability.

Arthroscopic anterior talofibular ligament repair (AATFLR) is a surgical strategy to treat chronic ankle instability (CAI) patients. This study identified risk factors that influenced the functional outcomes of AATFLR for CAI and developed prognostic nomogram for predicting functional outcomes in future AATFLR cases. Patients undergoing AATFLR from January 2016 to June 2022 with at least 10 months of follow-up were included in the study. The Karlsson Ankle Functional Score (KAFS) was evaluated preoperatively and at last follow-up visit. A total of 15 potential predictors including age, sex, body mass index, side affected, time from injury to surgery, sports-related injury, osteophyte, loose bodies, distal tibiofibular syndesmosis, ATFL avulsion fracture, Outerbridge classification of osteochondral lesions, postoperative immobilization method, ambulation time, walking time, and follow-up time, were recorded. We first used univariate binary logistic regression analysis to select the potential significant prognostic features, which were then subjected to the least absolute shrinkage and selection operator (LASSO) regression algorithm for final feature selection. A nomogram based on the regression model was developed to estimate the functional outcomes of patients. Models were validated internally using bootstrapping and externally by calculating their performance on a validation cohort. Overall, 200 ankles fit inclusion criteria. Of these 200, a total of 185 (92.5%) ankles were eligible and divided into development (n = 121) and validation (n = 64) cohorts. Four predictors were ultimately included in the prognostic nomogram model: age, sex, sports-related injury, and postoperative immobilization method. We found in our cohort that the significant predictors of poorer functional outcomes of AATFLR were postoperative immobilization with lower-leg cast, female sex, non-sports-related ankle sprain, and increasing age. Prognostic nomograms were created.

Novel cesium immobilization by alkali activation and cold consolidation of waste pharmaceutical glass

A new method of cesium immobilization has been successfully developed by combining alkali activation of boro-alumino-silicate glass and viscous flow sintering. Powdered glass from discarded pharmaceutical vials, suspended in a 2.5 M CsOH aqueous solution, underwent surface hydration as well as partial dissolution. Condensation reactions occurring at hydrated surface layers upon drying at 40 °C over 7 days resulted in welding of adjacent particles, forming a network that trapped newly formed gel and crystal phases. The newly formed phases including crystalline boro-pollucite (CsBSi2O6), were derived mostly from Cs+ ions reacting with the products of glass dissolution and exhibited a high chemical stability. Further stabilization was achieved through viscous flow sintering at 700 °C, resulting in the incorporation of Cs+ ions in a glass matrix. The effectiveness of the immobilization was confirmed by leaching test using the Materials Characterization Center-1 Standard (MCC-1). This innovative approach not only enhances the chemical stability of cesium waste forms, but also aligns with principles of cleaner production by repurposing pharmaceutical glass waste, promoting sustainable materials management.

Zinc oxide nanoparticles immobilized on polymeric porous matrix for water remediation

This work proposes a novel approach to producing composite membranes by immobilizing and blending ZnO nanoparticles within a polymer matrix. The focus is investigating how different immobilization techniques impact membrane performance in critical technological applications, including membrane fouling mitigation and photocatalytic degradation. Lab-synthesized ZnO nanostructures were immobilized within a natural cellulose acetate (CA) matrix using a spray coating technique. To ensure comprehensive exploration, CA membranes with 12% and 15% wt polymer concentrations, which demonstrated superior overall performance in previous studies, were cast and prepared. The membranes underwent phase inversion, and a specially prepared ZnO solution was sprayed onto the membrane surface, creating a unique blend of polymer and nanoparticles. This comparative study highlights distinctions between nanomaterial immobilization techniques (mixing and spray coating) while maintaining identical polymer content. Such insights are crucial for both industrial applications and laboratory-scale research. The photocatalytic degradation of the reactive and toxic dye methylene blue (MB) served as a model reaction, employing a UV light module. Results unequivocally demonstrated that, irrespective of the immobilization technique employed, the combination of CA and ZnO nanoparticles significantly enhanced the photocatalytic activity of the membrane in degrading methylene blue (MB). Specifically, the dye concentration decreased from 25 to approximately 8 mg/L for both the spray coating and bulk immobilization methods, resulting in 62% and 69% dye degradation, respectively. These findings underscore the versatility of different immobilization techniques in various aspects of membrane technology. The CA-ZnO composite exhibited efficacy in photocatalytic MB degradation tests, offering promising alternatives for designing polymeric membranes tailored for contaminant removal, particularly in treating textile dye-contaminated aqueous solutions. The exploration of diverse immobilization techniques for nanocomposites presents an exciting avenue for optimization in different membrane technological processes.

Oriented immobilization of antibodies through peptide ligands for ultrasensitive detection of gastrin 17 in human serum via lateral flow immunoassay

Gastrin 17 (G-17) is a major biomarker for the diagnosis of gastric cancer. As the serum concentrations of gastrin are low, highly sensitive detection methods are needed. Previous studies have shown that oriented immobilization of detection antibodies can improve the sensitivity of lateral flow immunoassay (LFIA) methods. Herein, the antibody binding capacity of four Fc-specific peptides reported in different studies was evaluated, and two peptides with better binding potency were further modified with cysteine or the peptide GAC at their C-terminus. The peptide FYWHCLDEGAC exhibited the highest antibody binding capacity and was applied to directly immobilize the anti-G-17 antibody on microspheres with carboxyl-functionalized surfaces and europium-based time-resolved fluorescence. An LFIA method was developed to detect G-17 in human serum, and the limit of detection (LOD) of this method for G-17 was 0.08 pmol L-1, which was 10 times less than that of the nonoriented immobilization method. The working range of this method is 0.27 ∼ 600 pmol L-1, with a recovery rate of 85.2 % −106.7 % and a CV value less than 12.4 %. This method is easy to use, and the total detection process takes less than 20 min. The test results for the actual serum samples were consistent with the commercial kit results (R2 > 0.95), demonstrating that the method can be utilized for point-of-care testing of G-17. This approach to orientedly immobilize antibodies on nanomaterials can be used to develop sensitive LFIA methods for various molecules.

Comparison of the forearm rotation restriction capacities of four upper-extremity immobilization methods: there is no difference between single and double sugar tong splinting

BackgroundThe aim of this study was to compare the effects of four different immobilization methods [single sugar tong splint (SSTS), double sugar tong splint (DSTS), short arm cast (SAC), and long arm cast (LAC)] commonly used for restricting forearm rotation in the upper extremity.MethodsForty healthy volunteers were included in the study. Dominant extremities were used for measurements. Basal pronation and supination of the forearm were measured with a custom-made goniometer, and the total rotation arc was calculated without any immobilization. Next, the measurements were repeated with the SAC, LAC, SSTS and DSTS. Each measurement was compared to the baseline value, and the percentage of rotation restriction was calculated.ResultsThe most superior restriction rates were observed for the LAC (p = 0.00). No statistically significant difference was detected between the SSTS and DSTS in terms of the restriction of supination, pronation or the rotation arc (p values, 1.00, 0.18, and 0.50, respectively). Statistically significant differences were not detected between the SAC and the SSTS in any of the three parameters (p values, 0.25; 1.00; 1.00, respectively). When the SAC and DSTS were compared, while there was no significant difference between the two methods in pronation (p = 0.50), a statistically significant difference was detected in supination (p = 0.01) and in the total rotation arc (p = 0.03).ConclusionThe LAC provides superior results in restricting forearm rotation. The SAC and SSTS had similar effects on forearm rotation. The DSTS, which contains, in addition to the SSTS, a sugar tong portion above the elbow, does not provide additional rotational stability.