Glutaraldehyde Concentration Research Articles

Immobilization of Β-galactosidase of Kluyveromyces lactis in mesoporous silica

β-galactosidase has been immobilized in different supports to improve its industrial performance. Thus, the research aimed to evaluate the covalent immobilization process of β-galactosidase from Kluyveromyces lactis in silica. The best immobilization conditions were evaluated based on the initial enzymatic activity, concentration of (3-Aminopropyl)triethoxysilane (APTES), and glutaraldehyde concentration using a central rotational composite design (CCRD). The influence of temperature and pH on enzymatic activity, thermal stability, pH, storage, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and reuse were also studied. The best immobilization conditions were at a concentration of 1.0 % APTES and 6.86 % glutaraldehyde, and an initial enzymatic activity of 21 U.mL−1. The immobilized β-galactosidase showed an optimal pH of 7.0, temperature of 30°C, and stability at pH of 7.5. Thermal stability was better at 20°C. In four reuse cycles, the enzyme maintained approximately 70 % of its initial activity. The stored enzyme (8°C) maintained 44 % activity after 105 days. The FT-IR allowed the visualization of the enzyme groups and the enzyme-support binding. SEM images showed the structure of the silica Using a fixed bed reactor, a lactose conversion of roughly 47 % was obtained. In general, the proposed method was efficient in lactose hydrolysis. Silica is considered a promising support for immobilizing β-galactosidase.

Magnetic hydrogel scaffold based on hyaluronic acid/chitosan and gelatin natural polymers

Owing to their native extracellular matrix-like features, magnetic hydrogels have been proven to be promising biomaterials as tissue engineering templates In the present work, magnetic hydrogels scaffold based on chitosan, gelatin, hyaluronic acid, containing Fe3O4 as magnetic nanoparticles (IONPs) were prepared. The prepared hydrogels were loaded with ciprofloxacin hydrochloride as a model drug. The magnetic hydrogel was prepared using different volumes of chitosan, 1%, gelatin, 10%, and hyaluronic acid, 1% in glutaraldehyde as the crosslinking agent and Fe3O4 as magnetic nanoparticles. The hydrogel scaffold and magnetic scaffold hydrogel samples were characterized by scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FTIR). The porosity, mechanical properties, swelling degree, and antibacterial activity of the hydrogel scaffold were also determined as well as the drug release profiles of the hydrogels. SEM imaging revealed that the magnetic hydrogel scaffold showed a relatively rough morphology with an irregular surface. The data obtained indicated that the hydrogel surface has three-dimensional porous microstructures and the porosity varied depending on the hydrogel formulation. The breaking load of the hydrogel scaffold increased from 1.361 Kgf to 4.98 Kgf by increasing the glutaraldehyde concentration from 0.2 mL to 0.8 mL. Swelling degree values in water were from 250 to 2000% after 24 h. The antibacterial activity of the hydrogel scaffold ranged from 54% to about 97% for Gram-positive bacteria (S. aureus) and from about 26–92% for Gram-negative bacteria (E. coli). The ciprofloxacin hydrochloride loaded hydrogel has a sustained release of ciprofloxacin hydrochloride over 10 h. The presence of IONPs gave a faster release of ciprofloxacin hydrochloride.

Stability of immobilized L-arginine deiminase from Penicillium chrysogenum and evaluation of its anticancer activity

The aim of the present work was to immobilize L-arginine deiminase on suitable supports such as chitosan, alginate, and silica gel to study its stability. Additionally, the study aims to investigate the anticancer effects of the free purified enzyme on hepatocellular carcinoma (Hep-G2) and breast cancer (MCF-7) cell lines. L-arginine deiminase (ADI: EC 3.5.3.6) was immobilized on chitosan, Ca-alginate, and silica gel, with immobilization efficiencies of 89.0%, 72.8%, and 66.5%, respectively. The optimal immobilization time for the highest efficiency was 4 h. Increasing the concentration of glutaraldehyde improved the immobilization efficiency of ADI on chitosan. The chitosan-immobilized ADI retained about 45% of its activity after 8 cycles. The optimal pH values were 6 for the free purified ADI and 7 for the chitosan-immobilized ADI. The optimal temperature increased from 40 °C for the free enzyme to 45 °C after immobilization. The activation energies for the free and chitosan-immobilized enzymes were 71.335 kJ/mol and 64.011 kJ/mol, respectively. The Km values for the free and chitosan-immobilized ADI were 0.76 mM and 0.77 mM, respectively, while the Vmax values were 80.0 U/mg protein for the free ADI and 71.4 U/mg protein for the chitosan-immobilized ADI. After 30 days of storage at 4 °C, the residual activities were 40% for the free purified ADI and 84% for the chitosan-immobilized ADI. At 25 °C, the residual activities were 10% for the free ADI and 75% for the chitosan-immobilized ADI. The chitosan-immobilized ADI exhibited significantly higher stability against proteases such as pepsin and trypsin compared to the free enzyme. The purified ADI also demonstrated enhanced potential anticancer effects and significant cytotoxicity against the Hep-G2 and MCF-7 tumor cell lines compared to doxorubicin. These findings suggest that purified ADI has potential as an anticancer agent, though further in-depth studies are required.

Polyphenol-treatment without preceding glutaraldehyde fixation: a potential paradigm change for bioprosthetic heart valves

Abstract Background Glutaraldehyde (GA) is the common fixative agent for bioprosthetic heart valves (BHVs). However, its chemical instability can expose calcium binding sites and, at commercially used concentrations, GA does not ensure effective immunological tolerance, triggering an immune response correlated to degeneration. Recently, polyphenols (PPs) achieved an almost complete xenoantigens inactivation in GA-fixed BHVs ensuring chemical stability of the treated tissue while improving mechanical characteristics and adding anti-infective and anti-thrombotic properties [1-4]. Purpose A new PP-based treatment has been introduced as a potential GA substitute in BHV manufacturing. The unique chemical properties of PPs permit them to interact with the tissue through stable chemical bonds without depolymerization over time, achieving several improvements that promise to extend the long-term durability of BHVs (Fig.1). Methods The study compared the effects of two cross-linking methods on bovine pericardial tissue: (1) traditional fixation in GA, and (2) treatment with PPs without GA. The type of chemical interaction between PPs and tissue was evaluated through nuclear magnetic resonance. The xenoantigens inactivation was quantified in-vitro by ELISA test and in-vivo in a humanized mouse animal model. Biomechanical properties were assessed through uniaxial stress-strain tests and cross-link density through the shrinkage temperature test. The protective effect against bacterial adhesion was evaluated against a strain of S aureus, while the inhibition of thrombosis was evaluated in-vivo in a pig animal model and in-vitro in a blood-loop using bovine blood with radio-labeled platelets. Results PPs effectuated multiple chemical bonds with and within the pericardium including cross-links based on covalent and hydrogen bonds, stacking, and electrostatic interactions. The inactivation of over 90% of surface-xenoantigens of the treated tissue allowed for superior biocompatibility (compared to <50% by commercial GA concentrations). The increase in elongation exhibited by PP-treated tissue confirmed excellent biomechanical features (Fig.2) while a sufficient degree of cross-linking was demonstrated through an adequate shrinkage temperature. Furthermore, a significant degree of bacterial adhesion (86% inhibition evaluated with S. aureus) and thrombus formation (Fig.2, up to 90% inhibition) were observed. Conclusion There is a real clinical need for improved chemical stability, calcification resistance, and immunological tolerance of current BHVs (surgical and transcatheter). PP technology may substitute the use of GA extending their performance and durability, thereby opening trans-catheter heart valves to younger patients. Reducing the need for mechanical heart valves would also address the associated risks of lifelong anticoagulation therapy.Figure 1Figure 2

Laccase immobilized on amino modified magnetic biochar as a recyclable biocatalyst for efficient degradation of trichloroethylene

Bioremediation of trichloroethylene (TCE) contaminated groundwater has recently attracted considerable attention. In this study, laccase was immobilized on amino modified magnetic pine biochar (MBC-NH2) by adsorption-crosslinking-covalent binding method, and its application in the degradation of TCE was evaluated. MBC-NH2 was obtained from pine sawdust by calcination, magnetic modification and amino modification. MBC-NH2 had high specific surface area (71.3 m2/g), rich surface functional groups and good magnetism. Under the conditions of 25 °C, pH = 4, glutaraldehyde (GA) concentration of 7 %, crosslinking time of 1 h, laccase concentration of 0.75 mg/mL, and immobilization time of 7 h, the loading capacity of laccase on MBC-NH2 carrier was as high as 782 mg/g. Compared with free laccase, immobilized laccase showed higher pH stability and thermal stability, and its activity remained 48.5 % after being reused for 10 times, and 80.8 % after being stored at 4 °C for 30 days. The immobilized laccase exhibited a good degradation effect on TCE. At 25 °C, pH = 4, immobilized laccase concentration of 0.35 g/L, and initial TCE concentration of 10 mg/L, the degradation efficiency of TCE by immobilized laccase was as high as 92.1 % within 48 h. In addition, the degradation products of TCE were analyzed, and the results showed that immobilized laccase could degrade TCE into non-toxic products through epoxidation, hydroxylation, and dechlorination. The immobilized laccase biocatalyst prepared in this study can achieve efficient degradation of TCE, which provides a feasible solution for chlorinated pollution of water resources. These research results are of great significance for the synthesis of biocatalysts for the efficient degradation of chlorinated hydrocarbons.

Unlocking the electrochemical performance of glassy carbon electrodes by surface engineered, sustainable chitosan membranes

Chitosan coatings, derived from crustacean shell waste, possess inherent biocompatibility and biodegradability, rendering them suitable for various biomedical and environmental applications, including electrochemical biosensing. Its amine and hydroxyl functional groups offer abundant sites for chemical modifications to boost the charge transfer kinetics and provide excellent adhesion, enabling the construction of robust electrode-coating interfaces for electroanalysis. This study explores the role of electrostatically-driven chemical interactions and crosslinking density originating from different chitosan (Cs) and glutaraldehyde (Ga) concentrations in this aspect. Studying anionic ([Fe(CN)6]3−/4−), neutral (FcDM0/+), and cationic ([Ru(NH3)6]2+/3+) redox probes highlights the influence of Coulombic interactions with chitosan chains containing positively-charged pathways, calculated by DFT analysis. Our study reveals how a proper Ch-to-Ga ratio has a superior influence on the cross-linking efficacy and resultant charge transfer kinetics, which is primarily boosted by up to 20× analyte preconcentration increase, due to electrostatically-driven migration of negatively charged ferrocyanide ions toward positively charged chitosan hydrogel. Notably the surface engineering approach allows for a two-orders of magnitude enhancement in [Fe(CN)6]4− limit of detection, from 0.1 µM for bare GCE down to even 0.2 nM upon an adequate hydrogel modification.

Recombinant Esterase (BaCEm) Immobilized on Polyethyleneimine-Impregnated Mesoporous Silica SBA-15 Exhibits Outstanding Catalytic Performance.

A recombinant esterase, BaCEm, derived from Bacillus aryabhattai and heterologously expressed in Escherichia coli, was successfully immobilized on polyethyleneimine-impregnated mesoporous silica SBA-15. This immobilization utilized glutaraldehyde as a crosslinker. Optimal conditions were established with a PEI/SBA-15 ratio of 25% (w/w), a pH of 7.5, and a glutaraldehyde concentration of 0.5% (w/w), resulting in a loading capacity of 76.4mg/g, a recovery activity of 43.5%, and a specific activity of 7917 U/g for BaCEm. The immobilized BaCEm demonstrated high enantioselectivity, with an "E" value of 203.92, in the resolution assay of (R,S)-ethyl indoline-2-carboxylate. Notably, the immobilized enzyme, compared to its free counterpart, exhibited enhanced thermostability, maintaining 95.4% of its activity after 3h at 30°C. It also showed significant tolerance to organic solvents, retaining 48.4% and 28.7% residual activity in 10% v/v acetonitrile and acetone, respectively. Moreover, its storage stability was confirmed, with 68.5% residual activity preserved after 30days at 4°C. Remarkably, the immobilized BaCEm retained 58.1% of its activity after 10 reuse cycles, underscoring the potential of polyethyleneimine-impregnated mesoporous silica SBA-15 as an effective support for enzyme immobilization, promising for industrial applications.

Enhancement of stability and activity of RSD amylase from Paenibacillus lactis OPSA3 for biotechnological applications by covalent immobilization on green silver nanoparticles

The key challenge to the biotechnological applications of amylases is achieving high activity and stability under extreme pH, temperature and often high levels of enzyme denaturants. This study immobilized a novel raw starch-digesting (RSD) amylase from Paenibacillus lactis OPSA3 on glutaraldehyde-activated silver nanoparticles. Effects of time, glutaraldehyde concentration, pH, temperature, and enzyme concentration on immobilization were studied, and the immobilized enzymes were characterized. pH 9.0 was optimum for the enzyme immobilization. The maximum immobilization efficiency of 82.23 ± 7.99 % was achieved at 25 °C for 120 min. After immobilization, the optimum pH and temperature changed from 9.0 to 11.0 and 60 to 70, respectively. Immobilization reduced the amylase's activation energy (KJ/mol) from the initial 58.862 to 45.449 following immobilization. The Km of the amylase decreased after immobilization, while the Vmax increased. The immobilized amylase showed significantly greater storage and thermal stability than the free amylase. At 80, enzyme half-life (min) and D value (min) increased from 12.33 to 179.11 and 40.94 to 594.98, respectively. The immobilized amylase (80–88 %) had more stability to the effects of the studied surfactants than the free enzyme. It also showed improved stability in the presence of commercial detergents compared to the free enzyme. The amylase's enhanced kinetic parameters and stability following successful immobilization on silver nanoparticles indicate its potential for application in the range of biotechnological processes where alkaline- and temperature-stable amylases are employed.

Immobilized Burkholderia cepacia lipase and its application in selective enrichment of EPA by hydrolysis of fish oil

Eicosapentaenoic acid (EPA), an orally active Omega-3 long-chain polyunsaturated fatty acid, has attracted much attention for its medical and healthcare value. Due to a large amount of polyunsaturated fatty acids (PUFA) including docosahexanoic acid (DHA) in fish oil, the highly specific enrichment of EPA from fish oil is difficult to achieve. In our study, we conducted immobilization studies on Burkholderia cepacia lipase (BCL) and its application in the selective enrichment of EPA in fish oil. BCL was immobilized on resin LX201A by covalent crosslinking, and immobilization conditions including glutaraldehyde concentration, pH, time were optimized. The optimal immobilization conditions were 0.5% glutaraldehyde, 4 h, and pH 8.0. The loading rate of BCL reached to 93.5%, and its activity was up to 68263 U/g under the optimal immobilization conditions. After hydrolysis reaction of fish oil for 15h catalyzed by immobilized BCL, EPA content showed a more increase by 33.2%, while a slight increase by 0.78% in DHA content. Moreover, after recycling use for 10 times, the catalytic efficiency of immobilized BCL remained at 93.0%. These indicated that immobilized BCL possessed good selectivity, reusability and stability, providing great application potential in EPA selective enrichment in fish oil industry.

Design of gelatin cryogel scaffolds with the ability to release simvastatin for potential bone tissue engineering applications

Tissue engineering aims to improve or restore damaged tissues by using scaffolds, cells and bioactive agents. In tissue engineering, one of the most important concepts is the scaffold because it has a key role in keeping up and promoting the growth of the cells. It is also desirable to be able to load these scaffolds with drugs that induce tissue regeneration/formation. Based on this, in our study, gelatin cryogel scaffolds were developed for potential bone tissue engineering applications and simvastatin loading and release studies were performed. Simvastatin is lipoliphic in nature and this form is called inactive simvastatin (SV). It is modified to be in hydrophilic form and converted to the active form (SVA). For our study's drug loading and release process, simvastatin was used in both inactive and active forms. The blank cryogels and drug-loaded cryogels were prepared at different glutaraldehyde concentrations (1, 2, and 3%). The effect of the crosslinking agent and the amount of drug loaded were discussed with morphological and physicochemical analysis. As the glutaraldehyde concentration increased gradually, the pores size of the cryogels decreased and the swelling ratio decreased. For the release profile of simvastatin in both forms, we can say that it depended on the form (lipophilic and hydrophilic) of the loaded simvastatin.

Isolation and chemical immobilization of E. coli‐specific bacteriophage with NH2‐MIL‐101(Fe) MOF, a high photoluminescence rod‐shaped microcrystals for low‐level bacteria detection

As concern raised by the World Health Organization (WHO) of antibiotic‐resistant and bio‐defensive bacteria, a metal–organic framework (MOF) based optical biosensor came into consideration for precise, quick, and sensitive detection of Escherichia coli (E. coli) (ATCC 10799) using bacteriophage as a bio‐recognition element. In the present study, amine‐functionalized Fe‐based MOF, i.e., NH2‐MIL‐101(Fe), was synthesized by the solvothermal method (approx. 531–1106 nm in size and 20 mV zeta potentials by DLS) and further characterized by SEM, XRD, ATR‐FTIR, UV–VIS, and photoluminescent (PL) spectroscopy. The lytic bacteriophage was isolated from a sewage sample, purified, and concentrated using the ultra‐centrifugation method and achieved a high titer of 7.3 × 1012 PFU/ml. The concentration, stability, and accessible receptor binding domains (RBDs) of the biorecognition element for binding with their analytes play an important role in developing sensitive and specific biosensor systems. To fulfill the mentioned criteria, optimized glutaraldehyde concentration was estimated at 0.25%, at 30 °C for conjugating maximum bacteriophage titer of 8.6 × 105 PFU/ml for each 1 mg amine functionalized iron‐based MOF. The synthesized detection probe has shown excellent photoluminescence and antibacterial activity and achieved a detection limit of 652 CFU/ml over a bacterial detection concentration range from 5.78 × 101 to 5.78 × 106 CFU/ml for E. coli with 10–12 min of response time, high specificity, and long‐term stability even at room temperature. Therefore, it can be inferred that this MOF‐based strategy can be helpful in the specific and sensitive detection of various bacterial pathogens using bacteriophage as a bio‐recognition element.

Synthesis of hydrogels from biomaterials and their potential application in tissue engineering

In this study, a series of hydrogels were synthesized from chitosan(s) that was crosslinking with glutaraldehyde at different concentrations. Ascorbic acid in an acidic medium was used to facilitate non-covalent interactions. The chitosan(s) was obtained from shrimp cytoskeleton; while ascorbic acid was extracted from xoconostle juice. The hydrogel reaction was monitored by UV–vis spectroscopy (550 nm) to determine the reaction kinetics and reaction order at 60 °C. The hydrogels structures were characterized by NMR, FT-IR, HR-MS and SEM, while the degree of cross-linking was examined with TGA-DA. The extracellular matrices were obtained as stable hydrogels where reached maximum crosslinking was of 7 %, independent of glutaraldehyde quantity added. The rheological properties showed a behavior of weak gels and a dependence of crosslinking agent concentration on strength at different temperatures. The cytotoxicity assay showed that the gels had no adverse effects on cellular growth for all concentrations of glutaraldehyde.

Magnetic ligand fishing protocol combined with HPLC-FT-ICR-MS for screening potential α-Glucosidase inhibitors from UCG and in silico analysis

Uremic Clearance Granule (UCG) is a traditional Chinese medicines (TCMs) that has been recognized as potentially effective treatment for diabetic nephropathy (DN). However, the chemical composition and the hypoglycemic ingredients of UCG remain unclear. In this experiment, a magnetic ligand fishing protocol combined with HPLC coupled Fourier transform ion cyclotron resonance mass spectrometry (HPLC-FT-ICR-MS) technology was developed to screen and identify α-Glucosidase inhibitors from UCG. First, constituents of UCG was identified by HPLC-FT-ICR-MS. Next, α-Glucosidase coated Fe3O4@SiO2@NH2 (Fe3O4@SiO2@NH2@α-Glucosidase) nano composites was synthesized. The essential parameters (concentration of Glutaraldehyde (GA), ratio of Fe3O4@SiO2@NH2 to enzyme, crosslinking time and immobilization time) were optimized to obtain maximum enzyme activity and the performance of immobilized enzyme was compared with that of free enzyme. The α-Glucosidase inhibitory activities were then evaluated using autodock and the 4-Nitrophenyl-α-D-glucopyranoside (pNPG) method. As a result, 142 compounds were identified were identified by comparing the retention time, molecular ions and fragmentation behaviors with the reference compounds or the in-house database. 20 possible α-Glucosidase activity inhibitory components were identified using HPLC-FT-ICR-MS. Molecular docking and inhibition studies showed that 4 compuunds including Limonexic acid, Sanggenol A, Glabrone, Matrine were more likely to stronger α-Glucosidase inhibitory activities than acarbose. In conclusion, the proposed approach, which combined highly specific screening with HPLC-FT-ICR-MS, provided a powerful platform for discovering bioactive components from multi-component and multi-target traditional Chinese medicines (TCMs).

Enhanced proton conductivity and mechanical stability of crosslinked sodium alginate as a biopolymer electrolyte membrane in fuel cell application

Abstract Nafion is a commercial polymer membrane that is commonly used in fuel cell systems, despite its major limitations such as high fuel crossover and high manufacture cost. The production of sodium alginate (SA) blended membrane with crosslinking agent (glutaraldehyde) and plasticizer (glycerol) is one of several current efforts to discover an alternative membrane with improved proton conductivity and mechanical properties. In this study, SA biomembranes were prepared using solution casting method and dried at a certain temperature. Then, the prepared membranes were immersed with 5% glycerol in different concentrations of glutaraldehyde. The cross-linked biomembranes underwent various tests such as liquid uptake, swelling ratio, ion exchange capacity, proton conductivity and mechanical stability. The best membrane achieved the highest proton conductivity with a value of 8.28 mS cm-1 and mechanical stability with a value of 218.00 MPa. Glutaraldehyde made a positive modification and had a beneficial impact on the characteristics of SA. The incorporation of glutaraldehyde and glycerol within the biopolymer notably improved the otherwise lacking mechanical properties of SA.

A Novel Method for the Preparation of Casein-Fucoidan Composite Nanostructures.

The aim of the study was to develop casein-fucoidan composite nanostructures through the method of polyelectrolyte complexation and subsequent spray drying. To determine the optimal parameters for the preparation of the composite structures and to investigate the influence of the production and technological parameters on the main structural and morphological characteristics of the obtained structures, 3(k-p) fractional factorial design was applied. The independent variables (casein to fucoidan ratio, glutaraldehyde concentration, and spray intensity) were varied at three levels (low, medium, and high) and their effect on the yield, the average particle size, and the zeta potential were evaluated statistically. Based on the obtained results, models C1F1G1Sp.30, C1F1G2Sp.40, and C1F1G3Sp.50, which have an average particle size ranging from (0.265 ± 0.03) µm to (0.357 ± 0.02) µm, a production yield in the range (48.9 ± 2.9) % to (66.4 ± 2.2) %, and a zeta potential varying from (-20.12 ± 0.9) mV to (-25.71 ± 1.0) mV, were selected as optimal for further use as drug delivery systems.

Modification of a Carboxymethyl Cellulose/Poly(vinyl alcohol) Hydrogel Film with Citric Acid and Glutaraldehyde Crosslink Agents to Enhance the Anti-Inflammatory Effectiveness of Triamcinolone Acetonide in Wound Healing.

Anti-inflammatory wound healing involves targeted drug delivery to the wound site using hydrogel materials to prolong drug effectiveness. In this work, hydrogel films were fabricated using carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) crosslinked with citric acid (CA) and glutaraldehyde (GA) at different concentrations. The crosslinker densities were optimized with various CA (2-10% w/v) and GA (1-5% v/v) concentrations. The optimized crosslink densities in the hydrogel exhibited additional functional group peaks in the FT-IR spectra at 1740 cm-1 for the C=O stretching of the ester linkage in CA and at 1060 cm-1 for the C-O-C stretching of the ether group in GA. Significantly, the internal porous structures of hydrogel composite films improved density, swelling capacities, solubility percentage reduction, and decreased water retention capacities with optimized crosslinker densities. Therefore, these hydrogel composite films were utilized as drug carriers for controlled drug release within 24 h during medical treatment. Moreover, the hydrogel films demonstrated increased triamcinolone acetonide (TAA) absorption with higher crosslinker density, resulting in delayed drug release and improved TAA efficiency in anti-inflammatory activity. As a result, the modified hydrogel showed the capability of being an alternative material with enhanced anti-inflammatory efficiency with hydrogel films.

Optimization of the coating process in the PEGylated chitosan-based doped cobalt ferrite nanoparticles for hyperthermia applications using the Taguchi method

In this study, the parameters of coating process in the PEGylated chitosan-based doped cobalt ferrite nanoparticles for hyperthermia applications was optimized using the Taguchi method. The effect of chitosan and polyethylene glycol as well as the glutaraldehyde (crosslinker) contents on the structural, microstructural, and magnetic properties and the colloidal stability of the nanoparticles were investigated. Ultimately, to optimize the properties of the nanoparticles, the Taguchi method (L16 orthogonal array) was employed. The incorporation of the Ca2+ and Gd3+ into the spinel structure with an average crystallite size of 21 nm was successfully verified by X-ray diffraction (XRD) and the Rietveld refinement analysis. Moreover, thermogravimetric (TGA) analysis and Fourier-transform infrared spectroscopy (FT-IR) demonstrated the effective functionalization of the chitosan and polyethylene glycol coatings. Vibrating sample magnetometer (VSM) measurements revealed that saturation magnetization (Ms) was achieved in the range of 54.91–60.42 emu/g. Also, microstructural observations indicated that the coating layer can affect the particle size distribution and morphology. The Taguchi method identified that the glutaraldehyde content is the most expressive parameter influencing the nanoparticles’ properties, with the optimum properties achieved at chitosan, polyethylene glycol, and glutaraldehyde of 0.4 g, 0.08 g, and 1.2 ml, respectively. The antibacterial analysis confirmed the promising potential of the coated nanoparticles for biomedical applications. Furthermore, the magnetic heating efficiency of the synthesized nanoparticles was investigated in various concentrations of magnetic fluid, demonstrating their suitability for magnetic hyperthermia application.

Effect of glutaraldehyde and carbonyl iron concentration on the structure of gelatin-based ferrogels

Effect of glutaraldehyde and carbonyl iron concentration on the structure of gelatin-based ferrogels

Thixotropic chitosan hydrogels for biomedical applications: Unravelling the effect of chitosan concentration on the mechanical behaviour

Chitosan hydrogels are highly sought after in biomedical applications due to their biocompatibility, non-toxicity, and tunable mechanical properties. Nevertheless, achieving stable hydrogels with the required mechanical strength remains a notable obstacle. In this study, we prepared chitosan hydrogels with enhanced stability using minimal concentrations of glutaraldehyde to mitigate toxicity risks. The resulting hydrogel system is characterized by strong covalent bonds formed through imine and hydrogen bonding, facilitated by the aldehyde groups of glutaraldehyde. Rheological analyses reveal the viscoelastic properties of the hydrogels, showcasing stable gel-like structures with shear-thinning behavior, which are further enhanced with increasing chitosan concentration. Our observation demonstrates that the complex shear moduli of 0.5 - 1.5 w/v% chitosan hydrogel ranged between 3.08 kPa and 8.5 kPa, closely matching the shear moduli of the brain and connective tissues. The shear moduli obtained for the 2 w/v% (10.2 kPa) and 2.5 w/v% hydrogels (11.34 kPa) conform to the shear moduli of liver, fat, relaxed muscle, and breast gland tissue. Thixotropic studies reveal good structural recovery behaviour in the hydrogels. The swellability of 2 w/v% and 2.5 w/v% hydrogels (50–70 %) suggests their suitability for bone tissue engineering, with moderate porosity required for bone growth (60–75 %). Moreover, the yield stress values of 0.5 - 1.5 w/v% hydrogels satisfy the requirements for soft tissue engineering, while those of 2 and 2.5 w/v% match the requirements for bone tissue engineering. Our findings suggest that chitosan hydrogels of varying concentrations (0.5–2.5 % w/v) hold promise for a range of biomedical applications, including tissue engineering for brain, nerve, soft, and bone tissues, and wound dressing. This research addresses the pressing need for stable chitosan hydrogels with tailored mechanical properties, potentially offering solutions to challenges in biomedical materials design.

Mechanical characterisation of polylactic acid-alendronate bioscrew in different concentrations of glutaraldehyde

Background: Bioscrew is a developing innovation as a substitute to avoid re-surgery for screw removal; one of the bioscrew materials is polylactic acid (PLA). Alendronate plays a role in reducing osteoclastic activity, causing a decrease in osteoclast-mediated bone resorption, thereby accelerating the process of bone union. Objective: This study determines adding various glutaraldehyde concentrations to the bioscrew mechanical characteristics. Method: This study used the PLA bioscrew immersed into bovine hydroxyapatite (BHA)-gelatin (GEL)-alendronate (ALE) solution, then added with 0% (F1), 1% (F2), and 1,5% (F3) glutaraldehyde (GTA) as cross-link agent. Result: The pore diameter for F1, F2, and F3 were: 38.90±15.34; 29.01±8.94; and 30.58±7.40 μm, respectively. The flexural strength for F1, F2, and F3 were: 1.00±0.22, 1.18±0.13, and 1.11±0.16 MPa, respectively. The pull-out strength for F1, F2, and F3 were: 4.88 ± 0.79; 7.87 ± 0.24; and 7.65±1.02 N, respectively. The degradation rate for F1, F2, and F3 were: 14.40±2.08; 3.81±0.67; and 4.97±0.58 %, respectively. This study has found that glutaraldehyde concentrations significantly affect pull-out strength and degradation rate. The highest mechanical strength and slowest degradation rate for % weight loss was F2. Conclusion: Adding glutaraldehyde may enhance the mechanical characteristics of the bioscrew.