Synthesis of glutaraldehyde-modified silica/chitosan composites for the removal of water-soluble diclofenac sodium.

Composite materials are effective adsorbents for the removal of various types of contaminants, such as pharmaceutical products. However, they require improvement to achieve a good adsorption capacity. This study presents the development of a promising adsorbent: silica/chitosan modified with different proportions of glutaraldehyde, which involves the D-glucosamine units from chitosan. The developed materials were evaluated for their ability to remove diclofenac sodium. The adsorption data showed that the diclofenac adsorption efficiency increased with increasing degree of glutaraldehyde crosslinking. The equilibrium and kinetic data were well fit by the Liu and Elovich models, respectively, and the maximum adsorption capacity was 237.8 mg/g. Therefore, it can be assumed that the process is predominantly chemical and exothermic, with a high affinity between the adsorbents and diclofenac sodium. The adsorption mechanisms were investigated to better understand the interactions, and the predominance of covalent bonds with the self-polymerized glutaraldehyde was verified.

Multiplatform Protein Detection and Quantification Using Glutaraldehyde-Induced Fluorescence for 3D Systems.

Glutaraldehyde (GTA) is a dialdehyde used as biological fixative and its interaction with proteins like bovine serum albumin (BSA) has been well described. Additionally, GTA is known to induce fluorescence when interacting with BSA molecules. In this work, it is developed a new sensitive and reproducible method for BSA quantification using GTA crosslinking to endow fluorescence to BSA molecules. This method can be used with standard lab equipment, providing a low cost, fast-tracking and straightforward approach for BSA quantification. Techniques such as confocal laser scanning microscopy (CLSM) and spectrofluorometry are applied for quantitative assessment, and widefield fluorescence microscopy for qualitative assessment. Qualitative and quantitative correlations between BSA content and GTA-induced fluorescence are verified. BSA concentrations as low as 62.5 µg/mL are detected using CLSM. This method can be highly advantageous for protein quantification in three-dimensional hydrogel systems, specially to evaluate protein loading/release in protein delivery or molecular imprinting systems. Graphical Abstract Preparation and analysis of glutaraldehyde-induced protein-fluorescence in 3D hydrogels. Alginate-methacrylate hydrogels containing varying amounts of bovine serum albumin (BSA) are prepared by photopolymerization and then incubated in glutaraldehyde solutions. Samples observation is performed using confocal laser scanning microscopy, spectrofluorometry and widefield fluorescence microscopy. Data is processed and retrieves a quantitative correlation between protein content and fluorescence levels.

Synthesis and characterization of an injectable hyaluronic acid-polyaspartylhydrazide hydrogel.

The hydrogel produced by the reaction between a hyaluronic acid derivative (HAALD) and α,ß-polyaspartylhydrazide (PAHy) hydrogel was used for lacrimal duct studies. In order to improve the mechanical properties of HAALD-PAHy hydrogel, glutaraldehyde (GA) was used as a candidate to increase the mechanical properties of the hydrogel. The optimum mass ratio of the GA and PAHy was 1:50. HAALD-PAHy and HAALD-PAHy-GA50 were both synthesized in PBSA solution and characterized by different methods including gel content and swelling, rheological analysis, in vitro degradation and in vivo degradation via rheological analysis. The storage modulus (G') of the HAALD-PAHy-GA50 hydrogel reached 3800 Pa, i.e. (2.9±0.3 times higher than for HAALD-PAHy). The in vitro cytotoxicity test revealed that HAALD-PAHy-GA50 have a good biocompatibility and in vivo animal testing concluded that HAALD-PAHy-GA50 remains in the rabbit's lacrimal duct for 28 days.

Synthesis, characterization, and antibacterial activity of cross-linked chitosan-glutaraldehyde.

This present study deals with synthesis, characterization and antibacterial activity of cross-linked chitosan-glutaraldehyde. Results from this study indicated that cross-linked chitosan-glutaraldehyde markedly inhibited the growth of antibiotic-resistant Burkholderia cepacia complex regardless of bacterial species and incubation time while bacterial growth was unaffected by solid chitosan. Furthermore, high temperature treated cross-linked chitosan-glutaraldehyde showed strong antibacterial activity against the selected strain 0901 although the inhibitory effects varied with different temperatures. In addition, physical-chemical and structural characterization revealed that the cross-linking of chitosan with glutaraldehyde resulted in a rougher surface morphology, a characteristic Fourier transform infrared (FTIR) band at 1559 cm⁻¹, a specific X-ray diffraction peak centered at 2θ = 15°, a lower contents of carbon, hydrogen and nitrogen, and a higher stability of glucose units compared to chitosan based on scanning electron microscopic observation, FTIR spectra, X-ray diffraction pattern, as well as elemental and thermo gravimetric analysis. Overall, this study indicated that cross-linked chitosan-glutaraldehyde is promising to be developed as a new antibacterial drug.

Synthesis and characterization of glutaraldehyde-based crosslinked gelatin as a local hemostat sponge in surgery: an in vitro study.

In this study, preparation and characterization of soft crosslinked gelatin sponge for blood hemostasis application was considered. The effects of gelatin and crosslinker concentrations and altering freeze-drying temperature on sponges' density and structure, water absorption ability and biodegradation, cytotoxicity, mechanical properties and hemostatic effect were investigated. The density measurement indicated that the density of freeze-dried sponges increased when the freezing temperature was lowered. Scanning electron microscope and optical microscope images showed that gelatin sponges had uniform small pores (60 µm) after freezing at liquid nitrogen (-196°C). Biodegradation study demonstrated that the crosslinked sponges containing 1% and 2% gelatin lost respectively nearly 40 to 70% of their weight during 24 h. Prepared sponges showed desired water absorption ability (30-40 times of own dry weight) improved by lowering glutaraldehyde concentration. Cell toxicity was not detected in any of the samples. Compression modulus of sponges decreased four times (160 to 40 kPa) as the gelatin content varied from 2 to 1% w/v. Hemostasis study confirmed that the hemolytic ability of sponges increased through raising gelatin content and porosity of sponge. We suggest using gelatin sponges containing 1% w/v gelatin, 0.5% w/v glutaraldehyde frozen in liquid nitrogen, as a potential substitution for local hemostat absorbable sponge.

Nanomechanical properties of biochemically modified dentin bonded interfaces.

The effect of biomodification of dentin matrices using collagen cross-linkers, glutaraldehyde (GD) and grape seed extract (GSE), on the reduced modulus of elasticity (Er) and nanohardness (H) of the hybrid layer and underlying dentin was investigated at the dentin-resin bonded interface. The coronal dentin of nine molars were exposed and divided into groups: 5% GD, 6·5% GSE and control. Control samples were etched, bonded with Adper Single Bond Plus and Premise composite. GD and GSE were applied for 1 h prior to bonding procedures. After 24 h, samples were sectioned, and resin-dentin beams were either kept in distilled water or exposed to collagenase treatment for 24 h. Nano-indentations were performed at the hybrid layer and underlying dentin. GD and GSE treatment increased the Er and H of resin-dentin interface structures when compared to the control group (P<0·05), particularly the hybrid layer, and may be a promising novel approach to strengthen the dentin-resin bonded interface structures when using these adhesive system and resin-based composite.

[A method of following analysis for glutaraldehyde preparation].

A GC method for the products in cyclopentene oxidation to form glutaraldehyde in a liquid-liquid phase transfer reactive extraction process, which was a new process, is presented. A model GC-103 gas chromatograph equipped with FID was used. The column is a SS tube(phi 3 mm x 4 m) packed with 13% SE-30 coated on 101 white silanized support and a SS tube(phi 3 mm x 2 m) packed with 9.1% PEG-20M coated on the same support. Operating parameters: column temperature programming, 70 degrees C(4 min), then 10 degrees C/min to 140 degrees C(6 min); injector temperature, 185 degrees C; detector temperature, 185 degrees C; N2, 45 mL/min; H2, 65 mL/min; air, 300 mL/min. By using this method, cyclopentene, intermediates, solvents, glutaraldehyde, and byproducts were separated properly. The yield of glutaraldehyde determined by this method is more reliable than that determined by the chemical method.

Diazo- and azido-functionalized glutaraldehydes as cross-linking reagents and potential fixatives for electron microscopy.

The synthesis of diazo and perfluorophenyl azide (PFPA) functionalized glutaraldehydes 7 and 13a-d as new cross-linking reagents for bioconjugation and potential fixatives for electron microscopy is reported. A key step is the generation of the 1,5-dialdehyde structures by oxidative cleavage of the corresponding cyclopentene epoxide using HIO4 in aqueous tetrahydrofuran. A model reaction between 3-substituted glutaraldehyde 14 and 6-aminohexanoic acid resulted in the formation of pyridinium ion containing products with UV spectra comparable to those observed with glutaraldehyde itself. Thus modification of glutaraldehyde in the 3-position most probably did not significantly change its reactivity with amines under chemical-fixation conditions. Fixation of red blood cells by 7 demonstrates that as a fixative, 7 is comparable to glutaraldehyde.

Bonding to dentine with a simplified Gluma system.

In the present study, a number of modifications were introduced in the so-called Gluma resin--a new, simplified bonding system. The amount of acetone in its formulation was altered, or the acetone as well as part of the water were substituted by one of several volatile compounds with the purpose of obtaining a pretreatment of easier clinical application. Some modifications of the pH of the mixtures were also tried. Dentine specimens for shear bond testing were prepared and conditioned with an aluminium oxalate/glycine solution. The dentine surfaces were then treated with the modified Gluma resin mixtures before the placement of the composite resin. Gluma resin formulations containing tetrahydrofuran resulted in acceptable bond strengths, and with formulations of reduced pH, high bond strengths were obtained.

Optimized synthesis of polyglutaraldehyde nanoparticles using central composite design.

A central composite design was applied to the optimization of the synthesis of polyglutaraldehyde nanoparticles (PGNP). The effects of monomer concentration, surfactant concentration, pH, oxygen level, and stirring rate on the particle size, polydispersity, surface carboxyl group concentration, and yield of PGNP were investigated. The optimal conditions for the synthesis of PGNP were found to be: 7% (w/v) glutaraldehyde, 2.5% (w/v) dextran, pH 12, 70% (v/v) oxygen, and a stirring rate of 1080 rpm. Under these conditions, the values of the dependent variables adequately resembled those predicted by the model. The usefulness of these particles in the targeted delivery of cytotoxic drugs is discussed.

Agarose-polyaldehyde microsphere beads: synthesis and biomedical applications. Cell labeling, cell separation, affinity chromatography, and hemoperfusion.

Polyaldehyde microspheres, polyglutaraldehyde (PGL), and polyacrolein (PA) were synthesized by polymerizing glutaraldehyde and acrolein in the presence of an appropriate surfactant. The microspheres with average diameter of 0.2 micron were used for the specific labeling of human red blood cells (RBC) and mouse lymphocytes. The "naked" microspheres were encapsulated with agarose and formed agarose-polyaldehyde microsphere beads in sizes ranging from 50 microns up to 1 cm. The encapsulated beads, with diameters ranging from 50 to 150 microns were used as insoluble adsorbents for affinity purification of antibodies. Beads with diameters varied from 150 to 250 microns were used for cell fractionation purposes (mouse B splenocytes from T splenocytes). Uniform beads of 1 mm diameter were designed for hemoperfusion purposes. As a model, the removal in vitro of anti-BSA from immunized goat whole blood was studied.