Removal of Cr(VI) by glutaraldehyde-crosslinked chitosan encapsulating microscale zero-valent iron: Synthesis, mechanism, and longevity

Microscale zero-valent iron (mZVI) has shown great potential for groundwater Cr(VI) remediation. However, low Cr(VI) removal capacity caused by passivation restricted the wide use of mZVI. We prepared mZVI/GCS by encapsulating mZVI in a porous glutaraldehyde-crosslinked chitosan matrix, and the formation of the passivation layer was alleviated by reducing the contact between zero-valent iron particles. The average pore diameter of mZVI/GCS was 8.775 nm, which confirmed the mesoporous characteristic of this material. Results of batch experiments demonstrated that mZVI/GCS exhibited high Cr(VI) removal efficiency in a wide range of pH (2-10) and temperature (5-35°C). Common groundwater coexisting ions slightly affected mZVI/GCS. The material showed great reusability, and the average Cr(VI) removal efficiency was 90.41% during eight cycles. In this study, we also conducted kinetics and isotherms analysis. Pseudo-second-order model was the most matched kinetics model. The Cr(VI) adsorption process was fitted by both Langmuir and Freundlich isotherms models, and the maximum Langmuir adsorption capacity of mZVI/GCS reached 243.63 mg/g, which is higher than the adsorption capacities of materials reported in most of the previous studies. Notably, the column capacity for Cr(VI) removal of a mZVI/GCS-packed column was 6.4 times higher than that of a mZVI-packed column in a 50-day experiment. Therefore, mZVI/GCS with a porous structure effectively relieved passivation problems of mZVI and showed practical application prospects as groundwater Cr(VI) remediation material with practical application prospects.

Long-term disinfectant exposure on intestinal immunity and microbiome variation of grass carp

The gut microbiome is crucial in maintaining fish health homeostasis. Disinfectants can kill important pathogens and disinfect fish eggs, yet their effect on the immune pathways and intestinal microbiome in healthy fish remains unknown. In this study, we investigated the effects of two disinfectants on the transcriptome profiles, immunological response, and gut microbiota dynamics of grass carp over a four-week trial. In particular, aquatic water was disinfected with 80 μg/L glutaraldehyde or 50 μg/L povidone-iodine. We found that glutaraldehyde and povidone-iodine induced gut antioxidant system and depressed the function of grass carp digestive enzymes. The results of the 16S rDNA high-throughput sequencing identified a reduction in the diversity of grass carp gut microbiota following the disinfectant treatment. Moreover, transcriptome profiling revealed that disinfectant exposure altered the immune-related pathways of grass carp and inhibited the expression of inflammation and tight junction related genes. Finally, the histopathological observation and apoptosis detection results suggested that the long-term diet of disinfectant destroyed intestinal structural integrity and promoted apoptosis. In conclusion, long-term exposure to disinfectants was observed to reduce oxidation resistance, suppress the immune response, dysbiosis of the intestinal flora, and resulted in increasing the apoptosis in intestinal of grass carp.

Assessment of dimensional stability of novel VPES impression material at different time intervals with standard disinfectants

BACKGROUND

Vinyl polyether silicone (VPES) is a novel impression biomaterial made of a combination of vinyl polysiloxane (VPS) and polyether (PE). Thus, it is significant to assess its properties and behaviour under varied disinfectant test conditions. This study aimed to assess the dimensional stability of novel VPES impression material after immersion in standard disinfectants for different time intervals.

METHODS

Elastomeric impression material used -medium body regular set (Monophase) [Exa'lence GC America]. A total of 84 Specimens were fabricated using stainless steel die and ring (ADA specification 19). These samples were distributed into a control group (n=12) and a test group (n=72). The test group was divided into 3 groups, based on the type of disinfectant used - Group-A- 2% Glutaraldehyde, Group-B- 0. 5% Sodium hypochlorite and Group-C- 2% Chlorhexidine each test group was further divided into 2 subgroups (n=12/subgroup) based on time intervals for which each sample was immersed in the disinfectants - subgroup-1- 10 mins and Subgroup 2- 30 mins. After the impression material was set, it was removed from the ring and then it was washed in water for 15 seconds. Control group measurements were made immediately on a stereomicroscope and other samples were immersed in the three disinfection solutions for 10 mins and 30 mins to check the dimensional stability by measuring the distance between the lines generated by the stainless steel die on the samples using a stereomicroscope at x40 magnification.

RESULTS

The distance measured in the control group was 4397.2078 µm and 4396.1571 µm; for the test group Group-A- 2% Glutaraldehyde was 4396.4075 µm and 4394.5992 µm; Group-B- 0. 5% Sodium hypochlorite was 4394.5453 µm and 4389.4711 µm Group-C- 2% Chlorhexidine was 4395.2953 µm and 4387.1703 µm respectively for 10 mins and 30 mins. Percentage dimensional change was in the range of 0.02 - 0.25 for all the groups for 10 mins and 30 mins.

CONCLUSIONS

2 % Glutaraldehyde is the most suitable disinfectant for VPES elastomeric impression material in terms of dimensional stability and shows minimum dimensional changes as compared to that of 2% Chlorhexidine and 0.5% Sodium hypochlorite.

Aspergillus oryzae β-D-galactosidase immobilization on glutaraldehyde pre-activated amino-functionalized magnetic mesoporous silica: Performance, characteristics, and application in the preparation of sesaminol

Aspergillus oryzae β-D-Galactosidase (β-Gal) efficiently hydrolyzes sesaminol triglucoside into sesaminol, which has higher biological activity. However, β-Gal is difficult to be separate from the reaction mixture and limited by stability. To resolve these problems, β-Gal was immobilized on amino-functionalized magnetic nanoparticles mesoporous silica pre-activated with glutaraldehyde (Fe3O4@mSiO2-β-Gal), which was used for the first time to prepare sesaminol. Under the optimal conditions, the immobilization yield and recovered activity of β-Gal were 57.9 ± 0.3 % and 46.5 ± 0.9 %, and the enzymatic loading was 843 ± 21 Uenzyme/gsupport. The construction of Fe3O4@mSiO2-β-Gal was confirmed by various characterization methods, and the results indicated it was suitable for heterogeneous enzyme-catalyzed reactions. Fe3O4@mSiO2-β-Gal was readily separable under magnetic action and displayed improved activity in extreme pH and temperature conditions. After 45 days of storage at 4 °C, the activity of Fe3O4@mSiO2-β-Gal remained at 92.3 ± 2.8 %, which was 1.29 times than that of free enzyme, and its activity remained above 85 % after 10 cycles. Fe3O4@mSiO2-β-Gal displayed higher affinity and catalytic efficiency. The half-life was 1.41 longer than free enzymes at 55.0 °C. Fe3O4@mSiO2-β-Gal was employed as a catalyst to prepare sesaminol, achieving a 96.7 % conversion yield of sesaminol. The excellent stability and catalytic efficiency provide broad benefits and potential for biocatalytic industry applications.

Characterization of individual spores of two biological insecticides, Bacillus thuringiensis and Lysinibacillus sphaericus, in response to glutaraldehyde using single-cell optical approaches

Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus (Ls) are the most widely used microbial insecticides. Both encounter unfavorable environmental factors and pesticides in the field. Here, the responses of Bt and Ls spores to glutaraldehyde were characterized using Raman spectroscopy and differential interference contrast imaging at the single-cell level. Bt spores were more sensitive to glutaraldehyde than Ls spores under prolonged exposure: <1.0% of Bt spores were viable after 10 min of 0.5% (v/v) glutaraldehyde treatment, compared to ~ 20% of Ls spores. The Raman spectra of glutaraldehyde-treated Bt and Ls spores were almost identical to those of untreated spores; however, the germination process of individual spores was significantly altered. The time to onset of germination, the period of rapid Ca2+-2,6-pyridinedicarboxylic acid (CaDPA) release, and the period of cortex hydrolysis of treated Bt spores were significantly longer than those of untreated spores, with dodecylamine germination being particularly affected. Similarly, the germination of treated Ls spores was significantly prolonged, although the prolongation was less than that of Bt spores. Although the interiors of Bt and Ls spores were undamaged and CaDPA did not leak, proteins and structures involved in spore germination could be severely damaged, resulting in slower and significantly prolonged germination. This study provides insights into the impact of glutaraldehyde on bacterial spores at the single cell level and the variability in spore response to glutaraldehyde across species and populations.

Optimizing protein crosslinking control: Synergistic quenching effects of glycine, histidine, and lysine on glutaraldehyde reactions

Glutaraldehyde (GA) is a protein crosslinker widely used in biochemical and pharmaceutical research because it can rapidly stabilize and immobilize substrates via amine group interactions. However, controlling GA crosslinking is challenging owing to its swift reactivity and the influence of various solution conditions, such as pH and concentrations of the substrate and crosslinker. Although extensive research has focused on GA cross-linking mechanisms, studies on quenching, which is critical for preventing non-specific aggregation during prolonged storage, remain sparse. This study examines the quenching efficiency of a combined amino acid mixture of glycine, histidine, and lysine, which are commonly used as individual quenchers. Our findings, confirmed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis, demonstrate that this amino acid blend offers superior quenching compared to single amino acids, enhancing quenching activity across a wide pH spectrum. These results provide a novel approach for mitigating the high reactivity of GA with implications for improving sample preservation and stabilization in a range of biochemical applications, including microscopy and cell fixation.

Synergistic impact of natural gums and crosslinkers on the properties of oilseed meals based biopolymeric films

The waste material utilization from available agricultural resources can be beneficial in the field of economic, social, and environmental well-being. One of the main industrial crops used to manufacture oil from oilseeds worldwide is agricultural waste, such as the cake made from oilseeds. In this study, de-oiled cakes are used to create biopolymeric films. Three widely accessible oilseed meals viz. flaxseed, soybean, and mustard were gathered, ground, and sieved. A film forming suspension of defatted meals along with natural gums (acacia and xanthan gum) and crosslinkers (citric acid and glutaraldehyde) were formed. The suspension was cast into petri dishes and dried to produce smooth and even films. The physical, functional, color, thermal and morphological properties of the oilseed meals-gums crosslinked biopolymeric film were evaluated and statistical analysis was performed. The solubility was found to be decreased and tensile strength was increased with the addition of citric acid and increase in tensile strength. There was significant difference observed in the values of elongation at break after addition of citric acid as crosslinker. The research shows how oilseed meals enriched with natural gum and crosslinkers may be converted into biopolymeric films, which can then be used in food packaging to lessen reliance on petroleum-based, non-biodegradable plastics.

Effect of adhesive components in experimental fluoride varnish on fluoride release within 30 days in vitro study

We aimed to determine whether adhesive components could increase the release time of effective fluoride concentration from an experimental fluoride varnish applied to bovine teeth. An experimental fluoride varnish containing 5% sodium fluoride (EX1) was prepared and combined with 35% hydroxyethyl methacrylate (HEMA) (EX2), 5% glutaraldehyde (EX3), or 35% HEMA/5% glutaraldehyde mixture (EX4). Two commercially available fluoride varnishes were used for comparison. Each group was applied to bovine incisors, and the fluoride release and pH were monitored for 30 days. Cell viability analysis, scanning electron microscopy, and energy-dispersive spectroscopy were performed. EX4 released the highest and most effective concentration of fluoride for the longest period and reached neutral pH at the earliest; the release was maintained for up to 30 days without cytotoxicity. In conclusion, EX4 is considered to be the most effective varnish to prevent dental caries.

Cyanophycin modifications for applications in tissue scaffolding

Cyanophycin (CGP) is a polypeptide consisting of amino acids-aspartic acid in the backbone and arginine in the side chain. Owing to its resemblance to cell adhesive motifs in the body, it can be considered suitable for use in biomedical applications as a novel component to facilitate cell attachment and tissue regeneration. Although it has vast potential applications, starting with nutrition, through drug delivery and tissue engineering to the production of value-added chemicals and biomaterials, CGP has not been brought to the industry yet. To develop scaffolds using CGP powder produced by bacteria, its properties (e.g., biocompatibility, morphology, biodegradability, and mechanical strength) should be tailored in terms of the requirements of the targeted tissue. Crosslinking commonly stands for a primary modification method for renovating biomaterial features to these extents. Herein, we aimed to crosslink CGP for the first time and present a comparative study of different methods of CGP crosslinking including chemical, physical, and enzymatic methods by utilizing glutaraldehyde (GTA), UV exposure, genipin, 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS), and monoamine oxidase (MAO). Crosslinking efficacy varied among the samples crosslinked via the different crosslinking methods. All crosslinked CGP were non-cytotoxic to L929 cells, except for the groups with higher GTA concentrations. We conclude that CGP is a promising candidate for scaffolding purposes to be used as part of a composite with other biomaterials to maintain the integrity of scaffolds. The initiative study demonstrated the unknown characteristics of crosslinked CGP, even though its feasibility for biomedical applications should be confirmed by further examinations. KEY POINTS: • Cyanophycin was crosslinked by 5 different methods • Crosslinked cyanophycin is non-cytotoxic to L929 cells • Crosslinked cyanophycin is a promising new material for scaffolding purposes.

Effects of glutaraldehyde and povidone-iodine on apoptosis of grass carp liver and hepatocytes

Since disinfectants are used all over the world to treat illnesses in people and other animals, they pose a major risk to human health. The comprehensive effects of disinfectant treatments on fish liver, especially the impacts on oxidative stress, toxicological effects, transcriptome profiles, and apoptosis, have not yet been fully analyzed. In the current investigation, healthy grass carp were exposed to 80 μg/L glutaraldehyde or 50 μg/L povidone-iodine for 30 days. First, the findings of enzyme activity tests demonstrated that the administration of glutaraldehyde could considerably increase oxidative stress by lowering T-SOD, CAT, and GPx and raising MDA. Furthermore, KEGG research revealed that exposure to glutaraldehyde and povidone-iodine stimulated the PPAR signal pathway. To further elucidate the transcriptome results, the relative expressions of related DEGs in the PPAR signal pathway were verified. Glutaraldehyde induced apoptosis in liver tissue of grass carp; however, it activated cytotoxicity and apoptosis in grass carp hepatocytes when exposed to glutaraldehyde or povidone-iodine. According to the current study, disinfectants can cause the impairment of the immune system, oxidative stress, and attenuation of the PPAR signal pathway in the liver of grass carp, making them detrimental as dietary supplements for grass carp, particularly in the aquaculture sector.

Rapid formation of carbon nanotubes-natural rubber films cured with glutaraldehyde for reducing percolation threshold concentration

Carbon nanotubes (CNTs) filled natural rubber (NR) composites with various CNT contents at 0, 1, 2, 3, 4 and 5 phr were prepared by latex mixing method using glutaraldehyde as curing agent. This work aims to improve the electrical and mechanical properties of CNT filled NR vulcanizates. The CNT dispersion of NR composites was clarified using dispersion grader, optical microscopy and scanning electron microscopy. The electrical properties of NR composites in the existing of CNT networks were studied by following the well-known percolation theory. It was observed that the NR composites exhibited low percolation threshold at 0.98 phr of CNT. Moreover, a three-dimensional network formation of CNT in the NR composites was observed and it is indicated by the t-value of 1.67. The mechanical properties of NR composites in terms of modulus, tensile strength and hardness properties were increased upon the addition of CNT to the optimum mechanical properties at 1 phr of CNT. Therefore, the present work is found the novelty of the study that the conductive rubber latex film can be produced using GA as low-temperature curing agent which enhanced good electrical properties. Moreover, this work is found to be beneficial in case of conductive rubber latex film that requires high modulus at low strain. The additional advantage of this system is the curing process occurs at low-temperature using GA and it can be easily processed.

Performance of self-etching adhesives on caries-affected primary dentin treated with glutaraldehyde or silver diamine fluoride

OBJECTIVES

to evaluate the quality and stability of adhesive interfaces established by self-etching adhesives on caries-affected primary dentin (CAD) treated with glutaraldehyde (GA) or silver diamine fluoride (SDF).

METHODS

42 primary molars were exposed to a microbiological caries-inducing protocol and divided into 6 groups according to the adhesive system (Clearfil SE - CL or FL Bond II - FL) and pretreatment (water, GA or SDF) applied on CAD. One tooth from each group was analyzed for surface modification using infrared spectroscopy. Crowns were restored with resin composite (n = 36) and cut into beams and slices. The beams were subjected to microtensile testing, Raman spectroscopy and SEM after 24 h and 6 months of storage. The slices were analyzed using Micro-Raman spectroscopy to determine the diffusion zone thickness (DZ) in each period. Data were analyzed by ANOVA and Tukey or Kruskal-Wallis and Dunn tests (α = 0.05%).

RESULTS

SDF reduced the immediate bond strength for both adhesives. The control groups showed a decrease in BS after 6 months in artificial saliva. GA increased immediate DZ for FL, while SDF had the opposite effect on CL. GA decreased the DZ for FL at 6 months. There was a predominance of adhesive failures with areas of cohesive dentin fractures within control groups.

SIGNIFICANCE

Modifications caused by dentin surface treatments may directly affect the performance of adhesive systems and the quality and stability of adhesive restorations.

Knowledge about methods of disinfection of dental impression among dentists from Ecuador post SARS-COV-2 pandemic

Purpose

The aim of this study is to evaluate the understanding of the management of methods and practices of disinfection of dental impressions applied by general dentists and specialists in oral rehabilitation, post SARS-COV-2 pandemic.

Introduction

The oral cavity has a favorable environment for the growth and multiplication of bacteria and viruses, serving as the gateway to viruses such as SARS CoV-2 virus. Given that patients may be hosts of this infectious disease, stricter biosecurity measures in dental offices and a better understanding of the disinfection processes of dental impressions should be considered in addition to avoiding cross-infections, which are very common in our work environment.

Materials and methods

Descriptive, analytical, survey with the topic "Methods and practices of disinfection of dental impressions" that was composed of 14 questions based in OHPD (Oral Health Preventive Dentistry), n = 452 respondents who met the following inclusion criteria: general practice dentists from Ecuador who actively take dental impressions, specialists in oral rehabilitation with 5 years of experience, surveys with information of complete items, n = 270 professionals; n = 192 general dentists, dental hygienist and n = 78 oral rehabilitation specialists.

Results

n = 270 professionals evaluated, with a mean of p = 0.0. At 426 responses with a p value of <0.05, 30.4 % of responses indicated ignorance in the management of dental impressions, with a standard deviation of 2.744, with significant differences between professions (p = 0.035) and higher average knowledge of sample management within specialist dentists, (Chi p = 0.410 p > 0.05).

Conclusion

The understanding of the management of dental impressions among general dentists and specialists in oral rehabilitation is limited.

Cyclic extraction of phosphate from soybean meal using immobilized Aspergillus oryzae SBS50 phytase

Phytase enzyme found in plants, animals, and microorganisms is mainly involved in catalyzing the systematic removal of a phosphate group from phytic acid. Enzyme immobilization is one of the cost-effective methods for the wide usage of enzymes in the industrial sector. This paper reports the covalent immobilization of phytase on glutaraldehyde-activated aluminum oxide beads. The immobilization yield, efficiency, and activation energy were found to be 47.8%, 71.5%, and 15.78 J/mol, respectively. The bound enzyme displayed a shift in pH optima from 5.5 to 4.5, which is more beneficial to increase digestibility in comparison with the free enzyme. Immobilized phytase retained 42.60% of its activity after 1.0 h incubation at 80 °C, whereas free enzyme retained only 4.20% of its activity. Thermodynami increase in half-lives, D-values, enthalpy and free energy change after covalent immobilization could be credited to the enhanced stability. Immobilized phytase could be reused for five consecutive cycles retaining 51% of its initial activity with sodium phytate. The immobilized phytase was also found effective to hydrolyze the soybean meal, thus increasing the digestibility of poultry feed. The hydrolyzing reaction of soybean meal was carried out for six consecutive cycles and immobilized phytase retained nearly 50% of activity till the fifth cycle. The amount of phosphorus released after treatment with immobilized phytase was far higher than that from free phytase. Immobilization on this support is significant, as this support can sustain high mechanical resistance at high pH and temperature. This considerable stability and reusability of the bound enzyme may be advantageous for its industrial application.

Preparation and exchange transfusion effect of a double polymerization human umbilical cord haemoglobin of red blood cell substitute

The development of haemoglobin-based oxygen carrier (HBOC) is an excellent supplement to pre-hospital emergency blood transfusions. In this study, a new type of HBOC was prepared by using human cord haemoglobin (HCHb) and glutaraldehyde (GDA) and Bis(3,5-dibromosalicyl) fumarate (DBBF) to modify (DBBF-GDA-HCHb), the changes of physicochemical indexes during its preparation were evaluated, while a traditional type of GDA-HCHb was prepared, and the oxygen-carrying capacity of two type of HBOC was evaluated by a rat model of 135.0% exchange transfusion (ET). Eighteen SD male rats were selected, and were randomly divided into control group (5.0% albumin), DBBF-GDA-HCHb group and GDA-HCHb group. The 12 h survival rate of the C group was 16.67%, and the two HBOC groups were both 83.33%. Compared with GDA-HCHb, DBBF-GDA-HCHb can reduce lactic acid content by supplying oxygen to hypoxic tissues in a more timely manner, and can also can improve the reduction of MAP due to ischaemia.

The Relationship Between the Cross-Linker on Chitosan-Coated Magnetic Nanoparticles and the Properties of Immobilized Papain

The immobilized enzymes' properties can be affected by cross-linkers on the surface of supports. To study how cross-linkers alter enzymes function, chitosan-coated magnetic nanoparticles (CMNPs) with immobilized papain were prepared using glutaraldehyde and or genipin, and then, the properties of the nanoparticles and the immobilized enzymes were assessed. The Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), and X-Ray Diffraction (XRD) results showed that the CMNPs were prepared and papain molecules were immobilized on CMNPs by glutaraldehyde (CMNP-Glu-Papain) or by genipin (CMNP-Gen-Papain). Also, the results associated with enzymes activity indicated that the immobilization by glutaraldehyde and genipin increased the pH optimum of papain from 7 to 7.5 and 9, respectively. The kinetic results indicated that the immobilization by genipin slightly affects the enzyme affinity to the substrate. The stability results showed that CMNP-Gen-Papain has more thermal stability than CMNP-Glu-Papain and papain immobilization on CMNPs by genipin leads to stabilization of the enzyme in the presence of polar solvents, probably due to the more hydroxyl groups on CMNPs activated by genipin. In conclusion, this study suggests that there is a relationship between the types of cross-linker on the surface of supports, and the mechanism of action, kinetic parameters, and the stability of immobilized papain.

Effect of Glutaraldehyde Multipoint Covalent Treatments on Immobilized Lipase for Hydrolysis of Acidified Oil

Immobilized lipase is a green and sustainable catalyst for hydrolysis of acidified oil. Glutaraldehyde is widely used for lipase immobilization while the appropriate strategy optimizes the catalytic performance of lipase. In this research, lipase from Candida rugosa (CRL) was immobilized on spherical silica (SiO2) by glutaraldehyde multipoint covalent treatments, including covalent binding method and adsorption-crosslinking method. The enzymatic stability properties and performance in hydrolysis of refined oil and acidified oil were studied. We confirmed that the residual activity decreased while the stability increased because of the influence on secondary structure of lipase after multipoint covalent treatments. In the comparison of different immobilization strategies in multipoint covalent treatment, SiO2-CRL (covalent binding method) showed lower loading capacity than SiO2-CRL (adsorption-crosslinking method), resulting in low activity. However, SiO2-CRL (covalent binding method) showed better reusability and stability. Immobilized lipase via covalent binding method was more potential in the application of catalytic hydrolysis of acidified oils.

The long-term effect of glutaraldehyde on the bacterial community in anaerobic ammonium oxidation reactor

A 160-day incubation was performed with two anammox reactors (GA and CK) to investigate the effect of glutaraldehyde. The results indicated that anammox bacteria were very sensitive when glutaraldehyde in GA reactor increased to 40 mg/L, the nitrogen removal efficiency sharply decreased to 11%, only one-quarter of CK. Glutaraldehyde changed spatial distribution of exopolysaccharides, caused anammox bacteria (Brocadia CK_gra75) to disassociate from granules (24.70% of the reads in CK but only 14.09% in GA granules). Metagenome analysis indicated glutaraldehyde led to the denitrifier community succession from strains without nir (nitrite reductase) and nor (nitric oxide reductases) genes to those with them, and the rapid growth of denitrifiers with NodT (an outer membrane factor)-related efflux pumps replacing those with another TolC -related ones. Meanwhile, Brocadia CK_gra75 lacks the NodT proteins. This study provides important insight into community adaptation and potential resistance mechanism in an active anammox community after exposure to disinfectant.

Glutaraldehyde-based desensitizers' influence on bonding performances and dentin enzymatic activity of universal adhesives

OBJECTIVES

To evaluate the influence of two glutaraldehyde-based desensitizers (L: GLUMA Desensitizer, Heraeus Kulzer and G: GLUMA Desensitizer PowerGel) prior to the adhesive procedures on microtensile bond strength (µTBS) to dentin and endogenous enzymatic activity.

METHODS

Noncarious human third molars (N = 48) were cut to expose middle coronal dentin. Six experimental groups were formed according to the dentin pre-treatment (L or G) and the universal adhesives (IBU - iBond universal, Kulzer or AU - Adhese Universal, Ivoclar Vivadent) used in the self-etch mode (n = 8): 1) L/IBU; 2) G/IBU; 3) IBU; 4) L/AU; 5) G/AU; 6) AU. Specimens were cut into sticks and stressed until failure after 24 h (T0) or 1 yr of aging (T12). Additional 4 teeth were used for in situ zymography evaluation and data were statistically analyzed (α = 0.05).

RESULTS

Dentin pre-treatment, adhesive and aging statistically influenced bond strength and enzymatic activity (P<0.001). AU demonstrated higher bond strength values than IBU (P<0.001). The L resulted in higher bond strength compared to the G and control groups (P<0.001). aging statistically influenced bonding performance, especially when no dentin pre-treatment was performed (P<0.001). In situ zymography revealed that at baseline the control groups exhibited lower interfacial fluorescence compared to the experimental groups, irrespective of the adhesive used (P<0,001). However, after 1 yr of artificial storage, no differences were found among the groups (P>0.05).

CONCLUSIONS

Glutharldeadeyde-based products increased bond strength and determined a stabilization of the adhesive interface over time apparently not related to the MMPs inhibition.

CLINICAL SIGNIFICANCE

The results of this in vitro study suggest that the application of glutaraldehyde-based desensitizers prior to the adhesive procedures when associated with universal adhesives could result in increased bond strength and stabilization of the adhesive interface over time.

Vanillin crosslinked 3D porous chitosan hydrogel for biomedicine applications: Preparation and characterization

Crosslinked chitosan (CS) is one of the most useable hydrogels in biomedicine and tissue engineering. Unlike most chitosan crosslinkers that are toxic, such as glutaraldehyde, vanillin is a natural, biocompatible, and antimicrobial alternative. The crosslinking of chitosan and vanillin consists of Schiff base bonds between the amines of chitosan and the aldehydes of vanillin, in addition to hydrogen bonds formed across the network. In most studies, the combination of chitosan and vanillin has been investigated in small sizes (micro/nanoscale and biofilms). In this study, a chitosan-vanillin (CV) hydrogel was studied on a macroscale with a three-dimensional porous structure, and it was compared with chitosan crosslinked with glutaraldehyde (CG) on the same scale. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (FE-SEM) used to identify the bonds formed and examine the morphology of the hydrogels. The gel content, swelling, porosity, mechanical properties, cell viability (on L929 and mesenchymal cells), and antibacterial activity (against Escherichia coli and Staphylococcus aureus) of the samples were investigated. The results showed that the CV had both gel content and high porosity (>90%), with an interconnected porous network of uniform pore size. The CV hydrogel exhibited good antibacterial activity and cell viability. In terms of mechanical properties, CV has weaker mechanical properties compared to CG in the dry state, while the mechanical properties of CV have more improved in the swollen state compared to CG.

Enhancing the metal ion binding characteristics and reversal of selectivity of crosslinked chitosan sorbents through functionalisation for targeted applications

In this study, we report optimised synthesis of N-carboxymethylated chitosan (CM-Cts) and its crosslinking to obtain, for the first time, glutaraldehyde crosslinked N-carboxymethylated chitosan (CM-Cts-Glu) as a metal ion sorbent. CM-Cts and CM-Cts-Glu were characterised using FTIR and solid state 13C NMR techniques. As compared to epichlorohydrin, glutaraldehyde was found to be better suited for efficient synthesis of the crosslinked functionalised sorbent. CM-Cts-Glu showed better metal ion uptake properties compared to the crosslinked chitosan (Cts-Glu). Metal ion removal by CM-Cts-Glu was studied in detail under different conditions such as different initial solution concentrations, pH, presence of complexants and competing ions. Further, sorption-desorption kinetics was studied and it was shown that complete desorption and multiple cycles of reuse without any loss in capacity was feasible. The maximum Co(II) uptake obtained for CM-Cts-Glu was found to be 265 μmol/g, while for Cts-Glu it was 10 μmol/g. Metal ion sorption by CM-Cts-Glu was found to be through chelation by the carboxylic acid functional groups present over the chitosan backbone. Utility of the CM-Cts-Glu under complexing decontamination formulations used in nuclear industry was ascertained. While Cts-Glu generally preferred iron over cobalt under complexing conditions, it was shown that the selectivity was reversed in favour of Co(II) in the functionalised sorbent, CM-Cts-Glu. N-carboxylation followed by crosslinking with glutaraldehyde was found to be a feasible approach for the generation of superior chitosan-based sorbents.

Effect of chemical disinfection on the dimensional stability of polyvinyl ether siloxane impression material: a systemic review and meta-analysis

BACKGROUND AND OBJECTIVES

Polyvinyl ether siloxane (PVES) possesses ideal characteristics for making precise and accurate dental impressions. PVES dimensional stability owes to its better polymeric properties derived from its parent materials poly ethers and polyvinyl siloxanes. As recommended use of chemical disinfecting agents is getting more popular, there is a growing concern associated with the effect of disinfectants on PVES dimensional stability. This study was aimed to understand the PVES behavior when subjected to chemical disinfectants.

MATERIALS AND METHODOLOGY

The data was collected from research studies retrieved from Google Scholar, Scopus, and PubMed using MeSH terms of keywords "vinyl polyether siloxane AND Disinfection" or (Vinyl polyether siloxane OR polyvinyl siloxane ether OR PVES) AND (disinfectant OR disinfection)" without any restriction to publication date. The PRISMA (Preferred Reporting Items for Systemic Review and Meta-Analysis) directions were observed during the data collection, screening of studies, and meta-analysis. The primary data were retrieved, and batch exported from databases using Harzing's Publish or Perish software; primary analysis was performed in Microsoft Excel, while statistical analysis for effect size, two-tailed p-values, and heterogeneity among studies was performed using Meta Essentials. The effect size was calculated using Hedge's g values at the 95% confidence level using the random-effects model. Heterogeneity among studies was measured using the Cochrane Q and I².

RESULTS AND CONCLUSION

Dental impressions made from the PVES elastomeric impression materials showed no significant changes in dimensional stability. Immersion in the chemical disinfectant for 10 min was associated with clinically irrelevant changes in the dimensions of the PVES impressions. Disinfection with sodium hypochlorite was associated with clinically significant changes in dimensions, with a two-tailed p-value of 0.049. Disinfection with 2-2.5% glutaraldehyde solution was not associated with any significant dimensional variability.

Robust cross-linked cyclodextrin glucanotransferase from Bacillus lehensis G1 aggregates using an improved cross-linker and a new co-aggregant for the production of cyclodextrins

One of the potentials of carrier-free cross-linked enzyme aggregates (CLEA) immobilization is the ability to be separated and reuse. Yet, it might be impeded by the poor mechanical stability resulting low recyclability. CLEA of CGTase from Bacillus lehensis G1 (CGTase G1-CLEA) using chitosan (CS) as a cross-linker demonstrated high activity recovery however, displayed poor reusability. Therefore, the relationship between mechanical strength and reusability is studied by enhancing the CS mechanical properties and applying a new co-aggregation approach. Herein, CS was chemically cross-linked with glutaraldehyde (GA) and GA was introduced as a co-aggregant (coGA). CGTase G1-CLEA developed using an improved synthesized chitosan-glutaraldehyde (CSGA) cross-linker and a new coGA technique showed to increase its mechanical stability which retained 63.4% and 52.2%, respectively compared to using CS that remained 33.1% of their initial activity after stirred at 500 rpm. The addition of GA impacted the morphology and interaction consequently stabilizing the CLEAs durability in production of cyclodextrins. As a result, the reusability of CGTase G1-CLEA with CSGA and coGA increased by 56.6% and 42.8%, respectively compared to previous CLEA after 5 cycles for 2 h of reaction. This verifies that the mechanical strength of immobilized enzyme influences the improvement of its operational stability.

New chitosan-biochar composite derived from agricultural waste for removing sulfamethoxazole antibiotics in water

This study aims to develop a new chitosan-biochar composite derived from agricultural waste for removing sulfamethoxazole (SMX) antibiotics in water. Biochar was prepared from orange peel (OB) and spent coffee grounds (SCB). To fabricate chitosan-biochar composites, chitosan and biochar were crosslinked with glutaraldehyde. Results showed that pH, adsorbent dosage, time, temperature, and initial concentrations have a significant impact on the SMX adsorption. The adsorption data was better described by Langmuir (with good regression) than Freundlich model. The highest adsorption capacity (Q_max) of SMX on OB, SCB, CTS-OB, and CTS-SCB were 3.49, 7.65, 7.24, and 14.73 mg/g, respectively. The Freundlich constant (K_F) values for adsorption capacity were 1.66, 1.91, 2.57, and 5.57 (mg^1-nLⁿ/g), respectively, for OB, SCB, CTS-OB, and CTS-SCB. Ion exchange, π bonding, hydrogen bonding and pore filling, were proposed as dominant mechanisms of SMX removal process.

Genipin and glutaraldehyde based laccase two-layers immobilization with improved properties: New biocatalysts with high potential for enzymatic removal of trace organic contaminants

This research proposes the preparation of a two-layer laccase biocatalyst using genipin or/and glutaraldehyde as cross-linking agents. The multilayer biocatalysts were prepared using different combinations of genipin and glutaraldehyde in the individual preparation of the first and second laccase layers. First, chitosan was treated with genipin or glutaraldehyde, followed by the immobilization of the first laccase layer to form a single-layer biocatalyst. Then, the immobilized laccases were coated once again with genipin or glutaraldehyde, and a new laccase layer was immobilized onto the system, resulting in the final two-layer biocatalyst. Compared to the single-layer biocatalysts, catalytic activity increased 1.7- and 3.4-fold when glutaraldehyde coating was used to prepare the second laccase layer. However, adding a second layer did not always produce more active biocatalysts, since the two-layer biocatalysts prepared with genipin (GenLacGenLac and GluLacGenLac) presented a decrease in activity of 65% and 28%, respectively. However, these two-layer biocatalysts prepared with genipin maintained 100% of their initial activity after 5 cycles of ABTS oxidation. Nevertheless, the two-layer, genipin-coated biocatalyst resulted in a higher removal of trace organic contaminants, since it removed 100% of mefenamic acid and 66% of acetaminophen, compared with the glutaraldehyde-coated biocatalyst, which removed 20% of mefenamic acid, and 18% of acetaminophen.

Three case reports of glutaraldehyde-induced chemical colitis

Currently, chemical colitis in clinical practice is mainly caused by iatrogenic factors. The disinfectant glutaraldehyde is one of the common drugs that can cause chemical colitis, but there are few reports about it. From August 2019 to August 2022, 1457 cases of colonoscopy were performed in the endoscopy room of the Second Affiliated Hospital of Zhejiang University School of Medicine and Songyang County People's Hospital, and 3 cases of chemical colitis caused by glutaraldehyde residue are discussed in this report. All 3 cases occurred on the same endoscopic system and same day. These 3 patients were hospitalized and treated with bowel rest, hydration, peroral Kangfuxin solution, dexamethasone combined with Kangfuxin solution local enema treatment, and empiric antibiotic. In conclusion, standardized management of cleaning and disinfection should be strengthened in departments carrying out enteroscopy, especially those using the concentrated glutaraldehyde immersion solution and cleaning after immersion, to prevent the occurrence of acute chemical enteritis related to disinfectant.

Reliable cell preparation protocol for Raman imaging to effectively differentiate normal leukocytes and leukemic blasts

Leukemias are a remarkably diverse group of malignancies originating from abnormal progenitor cells in the bone marrow. Leukemia subtypes are classified according to the cell type that has undergone neoplastic transformation using demanding and time-consuming methods. Alternative is Raman imaging that can be used both for living and fixed cells. However, considering the diversity of leukemic cell types and normal leukocytes, and the availability of different sample preparation protocols, the main objective of this work was to verify them for leukemia and normal blood cell samples for Raman imaging. The effect of glutaraldehyde (GA) fixation in a concentration gradient (0.1 %, 0.5 %, and 2.5 % GA) on the molecular structure of T-cell acute lymphoblastic leukemia (T-ALL) and peripheral blood mononuclear cells (PBMCs) was verified. Changes in the secondary structure of proteins within cells were indicated as the main effect of fixation, as shown by an increase in band intensity at 1041 cm^-1, characteristic for in-plane δ(CH) deformation in phenylalanine (Phe). Different sensitivity of mononuclear and leukemic cells to fixation was observed. While the 0.1 % concentration of GA was too low to preserve the cell structure for an extended period of time, a GA concentration of 0.5 % seemed optimal for both normal and malignant cells. Chemical changes in PBMCs samples stored for 11 days were also investigated, which manifested in numerous modifications in the secondary structure of proteins and the content of nucleic acids. The impact of cell preculturing for 72 h after unbanking was verified, and there was no significant effect on the molecular structure of cells fixed with 0.5 % GA. In summary, the developed protocol for the preparation of samples for Raman imaging allows for the effective differentiation of fixed normal leukocytes from malignant T lymphoblasts.

Ixora coccinea L. - A reliable source of nanocellulose for bio-adsorbent applications

Nanocellulose, a subset of nanomaterials made from cellulose, one of the world's most plentiful natural resources, has the potential to offer environmentally friendly, renewable, and sustainable building blocks with enhanced properties for a variety of applications in the nanotechnology field. This article describes the impact of glutaraldehyde (GA) on glycerol plasticized nanocellulose derived from I. coccinea L. plant root. Using a variety of characterization techniques, including Fourier Transform Infrared Spectroscopy (FTIR), X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), AFM, tensile and Brunauer-Emmett-Teller (BET) analysis, the effect of GA on glycerol plasticized nano-cellulose was investigated. The tensile modulus of the GA-crosslinked, 2 % glycerol-plasticized nanocellulose scaffolds is higher (88.82 MPa) than that of the regular nanocellulose scaffolds (78.8 MPa). The scaffold Young's modulus has been increased to 86.3 MPa. The results of the BET study proved that the surface area of the GA crosslinked nano-cellulose scaffold improved to129.703 m²/g. The larger surface area in turn results in a greater number of contact sites between consecutive fibers. This enhances the utility of the scaffold as a bio-adsorbent for waste water treatment. The absorbance of textile black dye and methylene blue dye in sunlight using nanocellulose composites as photocatalyst revealed a significant decrease in dye concentration after each hour, demonstrating the composites' bio-adsorbent property. The non-toxic nature, inertness, increased crystallinity index values, and good mechanical qualities are other characteristics of the GA-treated nanocellulose encourages its uses as product packaging, bioengineering materials, tissue engineering, and insulation coatings.

Synthesis, modification and application of fish skin gelatin-based hydrogel as sustainable and versatile bioresource of antidiabetic peptide

Gelatin hydrogel is widely employed in various fields, however, commercially available gelatin hydrogels are mostly derived from mammalian which has many disadvantages due to the supply and ethical issues. In this study, the properties of hydrogels from fish-derived collagen fabricated with varying Glutaraldehyde (GA) determined. The antidiabetic properties of salmon gelatin (SG) and tilapia gelatin (TG) was also evaluated against α-glucosidase. Glutaraldehyde-crosslinked salmon gelatin and tilapia gelatin were used, and compared with different concentrations of GA by 0.05 %, 0.1 %, and 0.15 %. Water absorbency, swelling, porosity, pore size and water retention of the hydrogels were dependent on the degree of crosslinking. The synthesis of hydrogels was confirmed by FTIR study. Scanning electron microscope (SEM) observation showed that all hydrogels have a porous structure with irregular shapes and heterogeneous morphology. Performance tests showed that gelatin-GA 0.05 % mixture had the best performance. Antidiabetic bioactivity in vitro and in silico tests showed that the active peptides of SG and TG showed a high binding affinity to α-glucosidase enzyme. In conclusion, SG and TG cross-linked GA 0.05 % have the potential as an antidiabetic agent and as a useful option over mammalian-derived gelatin.

Biotechnological application of Aspergillus oryzae β-galactosidase immobilized on glutaraldehyde modified zinc oxide nanoparticles

The current research demonstrates the synthesis of zinc oxide nanoparticles (ZnO-NPs) via green nanotechnology approach (Azatirachta indica leaves). The size of the synthesized ZnO-NPs was confirmed as 27 nm by TEM. Glutaraldehyde was used to modify the surface of the developed ZnO-NPs in order to promote covalent binding of Aspergillus oryzae β-galactosidase. Enzyme activity was achieved as 93% on glutaraldehyde modified ZnO-NPs. The immobilized enzyme exhibited significant enhancement in activity under extreme temperature and pH variations, as compared to the soluble β-galactosidase (SβG). It was further observed that the immobilized enzyme retained 58% activity at 5% galactose concentration. However, under similar experimental conditions, SβG showed 27% activity. Reusability of immobilized enzyme revealed that it retained 89% activity even after fifth repeated use, and hence could be recovered easily by centrifugation for repeated use in biotechnological applications. Batch reactor experiment indicates that the immobilized enzyme displayed 81% and 70% lactose hydrolysis at 50 °C and 60 °C, respectively as compared to 70% and 58% lactose hydrolysis by soluble enzyme under identical conditions after 9 h.

Immobilization of lipase on silica nanoparticles by adsorption followed by glutaraldehyde cross-linking

In this study, Candida antarctica lipase B was immobilized on silica (SiO₂) nanoparticles by physical adsorption, and then cross-linked with glutaraldehyde (GA) to prepare cross-linked immobilized lipase (CLIL). During the condition of 1.28 mg/mL lipase concentration, 25 ℃ temperature, 2 h adsorption time, 0.01% GA (V/V) 7.5 mL and 2 h cross-linking time, the highest recovery activity of CLIL reached 87.82 ± 0.07% (22.55 ± 0.025 U/mg). Scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) confirmed that lipase was immobilized on the surface of SiO₂ nanoparticles. The changes in secondary structures of CLIL indicated that cross-linking changed the secondary structure of lipase protein, which made the structure of CLIL more stable. Compared with the free lipase, the thermal stability and storage stability of CLIL was significantly improved, and the t_1/2 at 60 °C was extended. Studies had shown that it was a feasible method to obtain CLIL by cross-linking after adsorbing lipase on SiO₂ nanoparticles.

Disinfection of polyvinyl siloxane impression material using ozone gas, 0.1% riboflavin, glutaraldehyde, and microwave irradiation and their effect on physical properties

AIM

To assess the antimicrobial effect of ozone gas (OG) 0.1% riboflavin (RF), glutaraldehyde (GaH), and microwave irradiation (MI) on Polyvinyl siloxane impression material formerly colonized with E. coli, P. Aeruginosa, E. faecalis, and S.aureus and their effect on the physical properties MATERIAL AND METHODS: One hundred disk-shaped specimens (diameter 10 mm and thickness 3 mm) were developed by using polyvinylsiloxane impression material and inoculated by the American Type Culture Collection (ATCC) of E. coli, P. aeruginosa, E. faecalis, and S.aureus in an in-vitro setup. The samples were arbitrarily isolated into five groups and subjected for 3 min to the designated disinfection modality. Group 1 Control, group 2: GaH, group 3: 0.1% RF, group 4: MI, and group 5 OG. Following decontamination, the physical properties (contact angle, strain-in-compression, and tear strength) of impression materials were evaluated. Statistical analysis for CFU/mL (log10) for exposed E. coli, P. aeruginosa, E. faecalis, and S.aureus was performed by using analysis of variance (ANOVA) and Tukey's multiple comparison tests at a p-value of less than 0.05.

RESULTS

The most effective antimicrobial efficacy for impression disinfection against all scrutinized microbial colonies were displayed by group 5 OG and the lowest disinfection effectiveness was unveiled by the control group with no treatment. The intragroup comparison revealed that impression disinfection with GaH, MI, and ozone corroborated analogous antimicrobial efficacy(p > 0.05). The disinfecting capacity of the impression material with 0.1% RF was significantly less than MI, GaH, and OG (p < 0.05).

CONCLUSION

Disinfection of polyvinyl siloxane impression material with ozone gas, microwave irradiation, and glutaraldehyde demonstrated reasonable antimicrobial efficiencies against E. coli, P. aeruginosa, E. faecalis, and S.aureus with no detrimental effects on the physical properties of impression material. More studies are advocated to extrapolate the findings of the present study.

Glutaraldehyde base-cross-linked chitosan-silanol/Fe3O4 composite for removal of heavy metals and bacteria

We designed and synthesised a magnetic adsorbent (Fe₃O₄@Si-OH@CS-Glu) combining chitosan-silanol groups with glutaraldehyde as a cross-linking agent, which has improved physicochemical properties and can be used to remove multiple heavy metals and bacteria from polluted water. The adsorbent was characterised with SEM, XRD, FTIR, BET, VSM, and zeta potential. Under optimum conditions, the adsorption efficiencies of Fe₃O₄@Si-OH@CS-Glu for Cr⁶⁺, As⁵⁺, Hg²⁺, and Se⁶⁺ were as high as 90.5%, 73.5%, 91.6%, and 100% respectively. In addition, Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) can be removed after 2-4 adsorption cycles with 2.5 mg Fe₃O₄@Si-OH@CS-Glu. The main adsorption mechanism of the adsorbent for heavy metals and bacteria is electrostatic adsorption. Overall, the synthesised Fe₃O₄@Si-OH@CS-Glu adsorbent showed high removal efficiency and adsorption capacity with a stable structure and easy separation. It has promising applications for the removal of heavy metals and bacteria from water.

Developmental neurotoxicity induced by glutaraldehyde in neuron/astrocyte co-cultured cells and zebrafish

The genotoxicity, development toxicity, carcinogenicity, and acute or chronic toxic effects of glutaraldehyde (GA), particularly during occupational exposure through its use as a fixative, disinfectant, and preservative, are well-documented but its effects on neurotoxicity have not been investigated. We performed in vitro and in vivo studies to examine the developmental neurotoxicity (DNT) of GA. Neurite outgrowth was examined in an in vitro co-culture model consisting of SH-SY5Y human neuroblastoma cells and human astrocytes. Cell Counting Kit-8, lactate dehydrogenase assay, and high-content screening revealed that GA significantly inhibited neurite outgrowth at non-cytotoxic concentration. Further studies showed that GA upregulated the mRNA expression of the astrocyte markers GFAP and S100β and downregulated the expression of the neurodevelopmental genes Nestin, βIII-tubulin, GAP43, and MAP2. Furthermore, in vivo zebrafish embryo toxicity tests explored the effects of GA on neural morphogenesis. GA adversely affected the early development of zebrafish embryos, resulting in decreased survival, irregular hatching, and reduced heart rate in a time- and concentration-dependent manner. Furthermore, the width of the brain and spinal cord was reduced, and the myelination of Schwann cells and oligodendrocytes was decreased by GA in transgenic zebrafish lines. These data suggest that GAs have potential DNT in vitro and in vivo, highlighting the need for caution regarding the neurotoxicity of GA.

The influence of glutaraldehyde on the microscopic structure of human pericardium

OBJECTIVES

In our study we investigate the collagen structure of human pericardium microscopically in dependence of glutaraldehyde (GA) concentration and fixation time.

METHODS

Pericardial samples were taken from 9 patients aged 40+ years who underwent cardiac surgery, either coronary artery bypass surgery or valve implantation/reconstruction. Specimens were cut in five equal pieces and treated with GA at fixed concentrations (0.3125 %, 0.625 % or 1.25 %) but different exposer times (5 min, 10 min, 20 min, 30 min and 60 min). Elastica van Gieson (EvG) staining was used for microscopic examination of pericardial collagen structure.

RESULTS

The collagen structure studied microscopically depended on both GA incubation time and GA concentration. At low GA concentrations (0.3125 %, 0.625 %) and short incubation times, individual collagen fibers appeared separately. After one hour incubation period, single collagen fibers could not be distinguished at any GA concentration. For fixed incubation times no differences were seen in the collagen structure when 0.3125 % and 0.625 % GA were used. However, at a concentration of 1.25 % GA fusion of individual collagen fibers was already observed at low incubation times.

CONCLUSION

Pericardial collagen structure changes with increasing incubation time and increasing GA concentration by raising fusion of single fibers. For GA concentrations of ≤ 0.625 %, fiber fusion depends plainly on incubation time. That is relevant as this concentration is used in cardiac surgery. At a concentration of 1.25 % GA, single collagen fibers could not be separated, even at short incubation times. Fusion of individual collagen fibers and changes in appearance (less undulating) were assumed to be responsible for stiffening of GA-fixed pericardium.

plant root derived nanocellulose using polyethylene glycol-glutaraldehyde system

Nanocellulose fibers are widely acknowledged as a more sustainable alternative to polyimide and polyethylene terephthalate-based plastic films derived from petrochemicals. Cellulose is also utilised in packaging, tissue engineering, electronic, optical, and sensor applications, pharmaceutical applications, cosmetic applications, insulation, water filtration, and hygiene applications, as well as vascular grafts. In the present study to improve the tensile and thermal properties of cellulose nanofibers, polyethylene glycol (PEG 600) with varying concentrations was produced by solvent casting and chemically crosslinked with glutaraldehyde (GA). The effects of various PEG 600 concentrations on nanofibers and the morphology of the resulting nanofibers were investigated. The effects of GA on PEG-nanocellulose morphology, average diameter, tensile strength, elongation, and thermal characteristics were investigated. Strong (GA)-based acetal linkages are used to substitute secondary hydrogen bonds in nanocellulose films. The 1% PEG 600 plasticized nanocellulose scaffolds cross-linked with GA showed a higher tensile modulus (93 MPa) than its GA untreated nanocellulose scaffolds (69 MPa). The Young's modulus of the scaffold is increased up to 83.62 MPa. The crystallinity index values of GA-treated scaffolds were increased, and the mechanical characteristics were greatly improved, according to Fourier transform infrared (FTIR) and XRD analysis on the films. The thermogravimetric analysis (TG/DTG/DSC) of the GA treated plasticized nanocellulose scaffold showed maximum decomposition temperature (T_max) at 360.01 °C.

不同交联剂处理对脱细胞小肠黏膜下层多孔支架的影响

OBJECTIVE

To compare the effects of three different crosslinkers on the biocompatibility, physical and chemical properties of decellularized small intestinal submucosa (SIS) porous scaffolds.

METHODS

The SIS porous scaffolds were prepared by freeze-drying method and randomly divided into three groups, then crosslinked by glutaraldehyde (GA), 1-ethyl-3-(3-dimethylaminopropyl) carbodi-imide (EDC) and procyanidine (PA) respectively. To evaluate the physicochemical property of each sample in different groups, the following experiments were conducted. Macroscopic morphologies were observed and recorded. Microscopic morphologies of the scaffolds were observed using field emission scanning electron microscope (FESEM) and representative images were selected. Computer software (ImageJ) was used to calculate the pore size and porosity. The degree of crosslinking was determined by ninhydrin experiment. Collagenase degradation experiment was performed to assess the resistance of SIS scaffolds to enzyme degradation. To evaluate the mechanical properties, universal mechanical testing machine was used to determine the stress-strain curve and compression strength was calculated. Human bone marrow mesenchymal cells (hBMSCs) were cultured on the scaffolds after which cytotoxicity and cell proliferation were assessed.

RESULTS

All the scaffolds remained intact after different crosslinking treatments. The FESEM images showed uniformed interconnected micro structures of scaffolds in different groups. The pore size of EDC group[(161.90±13.44) μm] was significantly higher than GA group [(149.50±14.65) μm] and PA group[(140.10±12.06) μm] (P < 0.05). The porosity of PA group (79.62%±1.14%) was significantly lower than EDC group (85.11%±1.71%) and GA group (84.83%±1.89%) (P < 0.05). PA group showed the highest degree of crosslinking whereas the lowest swelling ratio. There was a significant difference in the swelling ratio of the three groups (P < 0.05). Regarding to the collagenase degradation experiment, the scaffolds in PA group showed a significantly lower weight loss rate than the other groups after 7 days degradation. The weight loss rates of GA group were significantly higher than those of the other groups on day 15, whereas the PA group had the lowest rate after 10 days and 15 days degradation. PA group showed better mechanical properties than the other two groups. More living cells could be seen in PA and EDC groups after live/dead cell staining. Additionally, the proliferation rate of hBMCSs was faster in PA and EDC groups than in GA group.

CONCLUSION

The scaffolds gained satisfying degree of crosslinking after three different crosslinking treatments. The samples after PA and EDC treatment had better physicochemical properties and biocompatibility compared with GA treatment. Crosslinking can be used as a promising and applicable method in the modification of SIS scaffolds.

Removal of Pb (II) and V (V) from aqueous solution by glutaraldehyde crosslinked chitosan and nanocomposites

In this paper, new adsorbents with high mechanical strength chitosan-graphene oxide (CS-GO) and chitosan-titanium dioxide (CS-TiO₂) were synthesized by using glutaraldehyde as crosslinking agent, and the adsorption behavior of Pb (II) and V (V) on them were investigated. The materials were characterized by scanning electron microscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The effects of initial metal ion concentration and contact time on the removal of V (V) and Pb (II) by CS-GO and CS-TiO₂ were investigated. Characterization results showed that the hydroxyl group of GO/TiO₂ reacted with the amino group of chitosan. A comparison of the kinetic models against experimental data showed that the kinetics react system was best described by the pseudo-second-order model. indicating that chemical adsorption was the main adsorption force. the Langmuir adsorption model and Freundlich model agreed well with the experimental data. The removal capacity of Pb (II) by CS-GO and CS-TiO₂ were lower than those of V (V). The uncross-linked -OH and CO were the main adsorptive sites for Pb (II) removal, while uncross-linked -OH and -NH₂ played an important role in removing V (V). These findings provided insights on the removing lead and vanadium pollution.

Rapid anticalcification treatment for glutaraldehyde-fixed autologous tissue in cardiovascular surgery

Background

Glutaraldehyde (GA)-fixed autologous tissues, including the pericardium, are widely used as patches and valve substitutes in cardiovascular surgery. However, GA treatment causes tissue calcification. No rapid anticalcification method has been established for use during surgery. Here, we aimed to establish a rapid anticalcification method using ethanol, as has already been demonstrated for bioprosthetic valves.

Methods

Thoracic aorta tissues were first fixed with GA for 3 min and then treated with ethanol for 0 (group 2), 10 (group 3), 20 (group 4), and 30 (group 5) min; untreated tissues (group 1) served as the control. The treated tissues were subdermally implanted into 3-week-old male Wistar rats and kept in place for 28 days. The calcification in each explant was semiquantitatively evaluated by annotating and measuring the area using virtual slides, and the data obtained were statistically analyzed.

Results

Semiquantitative analysis revealed that calcification of the implants from the untreated group (group 1; P = 0.0014) and groups 4 (P = 0.0014) and 5 (P = 0.0031) was significantly lower than that of implants from group 2. Moreover, implants from group 3 showed a tendency toward decreased calcification, although it was not significant (P = 0.0503).

Conclusions

A rapid ethanol treatment prevents calcification of GA-fixed tissues in a rat model of subdermal implantation. This method may facilitate effective and rapid anticalcification of autologous tissues for use during cardiovascular surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-022-01895-7.

Effect of glutaraldehyde and calcium chloride as different crosslinking agents on the characteristics of chitosan/cellulose nanocrystals scaffold

The effect of glutaraldehyde and calcium cations as covalent and ionic crosslinkers was investigated on the main characteristics of scaffolds based on chitosan and cellulose nanocrystals. Therefore, four different scaffolds based on chitosan/cellulose nanocrystals with different crosslinking methods were fabricated using the freeze-drying method for potential use in bone tissue engineering. The structural and chemical features of prepared scaffolds were studied by the FTIR technique. FESEM images revealed that all scaffold samples are porous three-dimensional networks in which the pores are connected. TGA analysis showed that the thermal stability of scaffolds based on chitosan/cellulose nanocrystals has not been changed significantly by using different crosslinking methods. The chitosan/cellulose nanocrystals scaffold crosslinked by glutaraldehyde represented the highest compressive strength and the uncrosslinked scaffold showed the highest swelling ratio in comparison to the other scaffolds. The fastest degradation rate belonged to the scaffold crosslinked by calcium cations. FESEM images and EDX analysis confirmed that fabricated scaffolds have good biomineralization ability. The cell viability and cell attachment results indicated that all four scaffolds support cell proliferation and cell adhesion. However, the viability of NIH3T3 fibroblast cells in the presence of glutaraldehyde-containing scaffolds was lower than that of other scaffolds.

Efficacy of chemical and Photoactivated disinfectants against Candida Albicans and assessment of hardness, roughness, and mass loss of acrylic denture base resin

AIM

The present study aimed to assess the antimicrobial efficacy of hematoporphyrin derivative, sodium hypochlorite (NaOCl), glutaraldehyde (GaH), and a chlorhexidine (CHX) on mass loss (ML), microhardness, and surface roughness (Ra) of acrylic denture base colonized with C. Albicans.

MATERIAL AND METHODS

A total of 40 heat cure acrylic resin dentures were fabricated and inoculated by the American Type Culture Collection (ATCC) of C. Albicans in an in-vitro situation. Specimens were divided into four groups (n=10) based on the method of disinfection. Hematoporphyrin derivatives, 1% NaOCl, 2% GaH, and 4% CHX.The pre and post candida (CFU/ml) counts were recorded before and after immersion. ML, microhardness, and Ra of acrylic denture were also assessed. Statistical analysis was executed for CFU/mL (log10) for exposed C. Albicans by two-way ANOVA and Tukey's multiple tests (p>0.05). For normality of the data, Dunnet's Simultaneous test was performed.

RESULTS

In terms of candida strain analysis, pretreatment to posttreatment comparisons revealed a reduction in mean Candida count in all groups (p<0.05). The highest ML value after post candida disinfection of acrylic denture was observed in 2% GaH (1.587 ± 0.25) treated specimens. The least microhardness value was found in group 1 when treated with hematoporphyrin (0.97 ± 0.22 VHN) which was significantly different from other groups (p<0.05). Group 1 surface treated with hematoporphyrin derivate (1.84 ± 0.22 μm) showed the highest Ra values (p<0.05).

CONCLUSION

Acrylic denture base resin colonized with C. Albicans when treated with a chemical disinfectant of 4% chlorhexidine displayed the highest antimicrobial efficacy with reduced mass loss, less surface roughness, and maximum denture hardness.

Multifunctional hydrogels based on oxidized pectin and gelatin for wound healing improvement

Gelatin (G) cross-linked with oxidized pectin (OP) was studied as a potential scaffold material for tissue engineering. The effect of oxidation on the chemical properties of pectin was investigated by determining the carbonyl and carboxyl amounts. The OP treatment led to a significant decrease of all values (Mn, Mw, [η] and Rh) determined by size exclusion chromatography (SEC) coupled on line with multiangle light scattering and viscometer detectors. Cross-linking parameters were elucidated by FTIR and TNBS assay. In general, the degree of crosslinking increased with the oxidation of pectin. It was found that the presence of the crosslinking agents caused a reduction in swelling and in the gelatin release which was determined by the BCA kit assay. From the hemolysis test, the membrane of red blood cells was not disrupted by the contact of films and the rate of release of hemoglobin was lower than 5%. The coagulation properties were evaluated by the dynamic blood clotting test. The G/OP hydrogels manifested a good activity of wound healing in the albino rats' model. Moreover, the films did not produce any unwilling symptoms. So, it was concluded that studied films have the potentiality to be used as wound healing biomaterials.

Wound dressing membranes based on immobilized Anisaldehyde onto (chitosan-GA-gelatin) copolymer: In-vitro and in-vivo evaluations

Herein, wound dressing membranes based on covalently linked Chitosan (Ch) to Gelatin (GE) via Glutaraldehyde (GA) to have (Ch-GA-GE) copolymer have been developed. In addition, Anisaldehyde (An) was immobilized onto Ch-GA-GE to has An-(Ch-GA-GE) membrane. The changes of the Ch-GA-GE membranes wettability, from 26 ± 1.3° to 45.3 ± 2.27° of the An-(Ch-GA-GE) copolymer membrane, indicating the reduction of copolymers hydrophilicity. The thermal characterization was done using TGA and DSC, while the morphological analysis was done using SEM. The antibacterial properties were assessed against four bacterial strains (P. aeruginosa, S. aureus, Streptococcus, and E. coli). In-vitro evaluation of the fabricated membranes to be used as wound dressings was investigated by measuring their hemocompatibility, cytotoxicity, and biodegradability. Finally, the in-vivo assessment of the developed membranes to encourage skin regeneration was assessed utilizing adult Wistar albino rats. The results illustrated that the An-(Ch-GA-GE) copolymer membranes significantly enhanced the rat's full-thickness injuries, as monitored by reducing the wound region. Furthermore, histological analyses of the injuries covered with An-(Ch-GA-GE) membranes demonstrated a notable re-epithelialisation contrasted with wounds treated with the cotton gauze Ch-GA-GE membranes dressings proving the efficiency of Anisaldehyde. Those findings indicate that the An-(Ch-GA-GE) membrane has considerable potential for wound healing and skin regeneration.

Replication of fouling in vitro in hollow fiber dialyzers by albumin immobilization

For designing and evaluating the dialyzer and investigating the optimal therapeutic conditions, in vitro studies bring us many useful findings. In hemodialysis, however, the membrane fouling due to protein molecules reduces solute removal performance. Therefore, we investigated a method for replicating the fouling in dialyzers in aqueous experiments. After the albumin solution was circulated in the test circuit with a dialyzer, a glutaraldehyde solution was pumped into the dialyzer to immobilize albumin on the hollow fiber membrane. Under various immobilization conditions, the permeability of creatinine and vitamin B₁₂ was evaluated by dialysis experiments. The creatinine clearance after immobilization of albumin was decreased, suggesting pore plugging by our fouling replication method. The glutaraldehyde crosslinked albumin molecules that adhered them to the membrane firmly. Moreover, the degree of fouling may be controlled by changing the concentration of albumin solution and the volume of glutaraldehyde solution used for immobilization. Our fouling replication method was applied to three types of polyester polymer alloy (PEPA) dialyzers and one polysulfone (PSf) dialyzer. This method enables to evaluate the permeability of various dialyzers with fouling in vitro that will be of great help in collecting data for designing dialyzers.

Advantages of decellularized bovine pericardial scaffolds compared to glutaraldehyde fixed bovine pericardial patches demonstrated in a 180-day implant ovine study

Glutaraldehyde (GA)-fixed bovine pericardial patches remain the cardiovascular industry standard despite reports of degradation, thickening, inflammation, calcification and lack of tissue remodelling. Decellularization provides the opportunity to attenuate some of these immune-mediated processes. This study compared the mechanical and morphological integrity of bovine pericardium that is GA-fixated (Glycar® patches) or decellularized (BPS), using a proprietary protocol, following implantation in an ovine model. The impact of the processing methods on tissue strength and morphology was assessed prior to implantation. Pericardial patches were then implanted in the descending aorta and main pulmonary artery of juvenile sheep (n = 6 per group) for 180 days, and clinically evaluated using echocardiography. At explanation, patches were evaluated for strength, calcification and biological interaction. Histology demonstrated a wave-like appearance of well-separated collagen fibers for BPS scaffolds that provided pore sizes adequate to promote fibroblast infiltration. The collagen of the Glycar® patches showed loss of collagen fiber integrity, making the collagen densely compacted, contributing to insignificant recipient cell infiltration. The clinical performance of both groups was excellent, and echocardiography confirmed the absence of aneurysm formation, calcification and degeneration. Explanted Glycar® patches demonstrated cells in abundance within the fibrous encapsulation that separated the implant from the host tissue. More importantly, the fibrous encapsulation also contributed to patch thickening of both the explanted aorta and pulmonary patches. The decellularized pericardial scaffolds demonstrated recellularization, resistance to calcification, re-endothelialization and adequate strength after 180-day implantation. The proprietary decellularization protocol produced pericardial scaffolds that could be considered as an alternative to GA-fixed pericardial patches.

Collective bacterial disinfection by opto-chemical treatment on mature biofilm in clinical endoscope

The present study proposes an innovative opto-chemical treatment using a basket-integrated optical device (BIOD) to disinfect mature bacterial biofilm on endoscope channels. A BIOD was designed to position an optical diffuser on the central axis of an endoscope channel and to distribute laser light concentrically to the bacterial biofilm on the channel surface. To apply thermal damage and oxidative stress to the bacterial biofilm, a low concentration of a crosslinking agent (glutaraldehyde ~0.5%) was combined with 808 nm infrared (IR) and 405 nm blue (BL) laser lights. The applied irradiances of IR and BL were 10 W/cm² and 1.6 W/cm² for Teflon channel model and 20 W/cm² and 3.2 W/cm² for a clinical model, respectively. Individual irradiation of either IR or BL for 180 s induced the maximum temperatures of 62 ± 2 °C and 53 ± 3 °C on the biofilm, respectively. The simultaneous opto-chemical treatment reduced a significant population of the bacterial biofilms (7.5-log₁₀ for Staphylococcus aureus and 7.1-log₁₀ for Pseudomonas aeruginosa), which were 2.9-fold and 3.9-fold higher than that of the standard treatment with 2% glutaraldehyde (GA) solution, respectively. The proposed opto-chemical disinfection method can help reduce multi-drug resistant bacteria and prevent cross-infection during the clinical usage of a flexible endoscope.

Postoperative sensitivity in posterior resin composite restorations with prior application of a glutaraldehyde-based desensitizing solution: A randomized clinical trial

OBJECTIVES

To evaluate the effect of a glutaraldehyde-based desensitizer on the postoperative sensitivity (POS) in posterior resin composite restorations up to 12 months using a universal adhesive (Tetric N-Bond Universal) with selective enamel etching (SE) or an etch-and-rinse (ER) strategy.

METHODS

Class I and class II resin composite restorations (n = 220) at least 3 mm deep were inserted in 55 subjects. The universal adhesive was applied using the SE (self-etch strategy on dentin with selective enamel etching) or the ER strategy, with or without prior application of a glutaraldehyde-based desensitizer (Gluma Desensitizer - GL) to form groups SEGL and ERGL. A bulk-fill resin composite (Tetric NCeram Bulk Fill) was used for all restorations. Spontaneous POS was assessed 7 days after the restorative procedure using the Visual Analog Scale (VAS) and the Numeric Rating Scale (NRS). After 7, 14, and 30 days of completing each restoration, the subjects were reassessed to evaluate POS caused by stimulation with an air blast, horizontal and vertical percussion. In addition, marginal discoloration, marginal adaptation, fracture, and recurrence of caries were evaluated using the FDI (World Dental Federation) criteria after 7 days and at 12 months.

RESULTS

No significant spontaneous or stimuli-induced POS was observed when restorations with or without GL were compared (p>0.05). A higher risk of spontaneous POS was observed within 7 days (40.0%; 95% CI 28.1 to 53.1), without statistically significant differences among groups. None of the participants reported POS at 12 months, however five restorations were considered clinically unsatisfactory (p > 0.05).

CONCLUSIONS

The previous application of GL did not significantly reduce spontaneous or stimuli-induced POS in posterior resin composite restorations at any time, regardless of the adhesive strategy used.

CLINICAL SIGNIFICANCE

The use of a glutaraldehyde-based desensitizing agent did not generate lower incidence of postoperative sensitivity in resin composite posterior restorations.

Stabilization of enzymes via immobilization: Multipoint covalent attachment and other stabilization strategies

The use of enzymes in industrial processes requires the improvement of their features in many instances. Enzyme immobilization, a requirement to facilitate the recovery and reuse of these water-soluble catalysts, is one of the tools that researchers may utilize to improve many of their properties. This review is focused on how enzyme immobilization may improve enzyme stability. Starting from the stabilization effects that an enzyme may experience by the mere fact of being inside a solid particle, we detail other possibilities to stabilize enzymes: generation of favorable enzyme environments, prevention of enzyme subunit dissociation in multimeric enzymes, generation of more stable enzyme conformations, or enzyme rigidification via multipoint covalent attachment. In this last point, we will discuss the features of an "ideal" immobilization protocol to maximize the intensity of the enzyme-support interactions. The most interesting active groups in the support (glutaraldehyde, epoxide, glyoxyl and vinyl sulfone) will be also presented, discussing their main properties and uses. Some instances in which the number of enzyme-support bonds is not directly related to a higher stabilization will be also presented. Finally, the possibility of coupling site-directed mutagenesis or chemical modification to get a more intense multipoint covalent immobilization will be discussed.

Use of Photosensitizer, Glutaraldehyde, alcohol and Ultrasonics in disinfection of polished and rough surfaces of self-curing polymethyl methacrylate denture base material

AIM

To assess the effectiveness of chemical, ultrasonic and photodynamic therapy (PDT) mediated disinfection against in-vitro biofilms colonized with C. albicans, S. oralis, and S. aureus on surfaces of PMMA (polymethylmethacrylate) denture base material.

MATERIALS AND METHODS

Fifty plates of PMMA were prepared with two different surface topography (rough and polished) analyzed by profilometry. Provenance culture (ATCC) of C. albicans, S. oralis, and S. aureus were inoculated on specimens and exposed to disinfection. The disinfection included Rosebengal (RB) 5 μM activated by a red LED, 2% glutaraldehyde, 70% Isopropyl alcohol, ultrasonic disinfection, and saline solution as a control. The antimicrobial efficacy was assessed by subsequently calculating viable counts after disinfection. The data were analyzed using analysis of variance (ANOVA) and Tukey's Post Hoc test.

RESULTS

The unpolished surface demonstrated the highest average surface roughness As 5.32±0.36 (μm) and root mean square roughness Rr 7.22±0.81 (μm) compared to the polished surface. Intergroup comparison demonstrated polished and rough PMMA plate disinfected with rose bengal, glutaraldehyde and alcohol-based disinfection exhibited comparable reduction against C. albicans and S. oralis CFU/mL (log10) (p>0.05). Whereas, this reduction was significantly higher on the rough and polished surface of PMMA when disinfected using ultrasounds for 30 sec (p<0.05). Rose Bengal was the most effective method of disinfection against S. aureus both on polished (0.17±0.13) and rough (0.44±0.22) denture plates (p<0.05).

CONCLUSION

The ultrasonic disinfection was most effective in reducing viable microbial counts. RB mediated PDT exhibited a more substantial reduction of the colonies of S.aureus.

Amine-rich quartz nanoparticles for Cu(II) chelation and their application as an efficient catalyst for oxidative degradation of Rhodamine B dye

The study describes the loading of the quartz SiO₂ nanoparticles (NPs) with (3-aminopropyl)triethoxysilane (APTES) linker with simultaneous lengthening of the linker through the terminal amine group by glutaraldehyde (GA). The reactive polyethylenimine (PEI) was introduced to the surface to increase the ability to capture Cu(II) ions. The composite got the abbreviation SiO₂/PEI-Cu(II). The Cu(II) ions were the active center with a peroxo-complex activation state. The composite characterization included scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron-dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) surface analyzer. The kinetics of the oxidative degradation of Rhodamine B (RhB) dye obeyed the pseudo-first order under flooding conditions. The reaction parameters including the catalyst dose, solution pH, initial concentration of reactants, and temperature got some attention. The obtained results showed that more than 91.7 ± 1% of RhB dye was degraded to CO₂, NH₄⁺, NO₃^-, H₂O, and some inorganic acids after 30 min as confirmed by gas chromatography mass spectrometry and total organic carbon (TOC) measurements. Also, GC-MS spectra for water samples drawn from the reaction in successive periods had suggested a conceivable degradation pathway for RhB by hydroxyl radicals. Degradation starts with de-alkylation then carboxyphenyl removal followed by two successive ring-opening stages. Both the effects of the catalyst recycling and treated water reusability on the reaction rate were studied. The catalyst provided noticeable stability over three consecutive cycles.