HA Gel Research Articles

Investigation of Mechanical Properties and Dye Adsorption Capacities of Novel Hydrophobic Association Nanocomposite Hydrogels

The preparation of high performance hydrogels has always been one of the research focuses in the area of soft matters and functional polymers. In this paper, a facile method was developed for the preparation of high performance hydrophobic association nanocomposite hydrogels (HANC gels) via in situ copolymerization of acrylamide (AM) and octadecyl methacrylate (OMA) in the aqueous suspension of hectorite clay Laponite HZ-200 (clay) with sodium dodecyl benzene sulfonate (SDBS). Tensile hysteresis curves showed that the hysteresis degrees between HANC gels and conventional hydrophobic association hydrogels (HA gels) were almost the same, but the tensile strength of the HANC gel reinforced by just 0.4 wt% clay at the strain of 1500% was already as 630% as the strength of the HA gel, which indicated that the mechanical properties of the HA gel were greatly enhanced by the introduction of a small amount of clay without increasing the internal friction in the hydrogel network. The effects of clay on the structure of HANC gels were further confirmed by swelling test, it was found that the addition of clay effectively maintained the structural integrity of HANC gels in watery environment and prevented the collapse of gel network. Moreover, HANC gels exhibited superior cationic dye adsorption capacity compared to HA gels due to the existence of abundant negative charges on the surfaces of clay nanosheets

Synthesis and characterization of nanocrystalline hydroxyapatite gel and its application as scaffold aggregation

The sol-gel process is a technique used to synthesize materials from colloidal suspensions and, therefore, is suitable for preparing materials in the nanoscale. In this work hydroxyapatite was used due to its known properties in tissue engineering. Hydroxyapatite Ca10(PO4)6(OH)2 is a bioactive ceramic which is found in the mineral phase of bone tissue and is known for its great potential in tissue engineering applications. For this reason, this material can be applied as particle aggregates on ceramic slurry, coating or film on materials with a poorer biological response than hydroxyapatite. In this work, hydroxyapatite gel was obtained by the sol-gel process and applied as nanoparticle aggregation in the mixture of hydroxyapatite and tricalcium phosphate to form a ceramic slurry. This process is the polymer foam replication technique used to produce scaffolds, which are used in tissue engineering. For HA gel characterization it was used enviromental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF). The crystallite size was calculated from XRD data using the Scherrer equation. The nanoparticles size before firing was approximately 5nm. The crystallite size calculated after calcination was approximately 63 nm. The EELS results showed that calcium phosphate was obtained before firing. After HA gel calcination at 500 ºC the XRD results showed hydroxyapatite with a small content of beta-TCP. The scaffolds obtained by polymer foam replication technique showed a morphology with adequate porosity for tissue engineering.

Preparation and Microstructure of Biomorphic Hydroxyapatite Using Extracted Beech Wood Template

Biomorphic hydroxyapatite (Bio-HA) was fabricated using extracted beech wood that was impregnated with HA sol followed by sintering at 600~1300 °C for 2 hours. The extraction using boiling 5% ammonia solution was helpful to bring more pores to benefit to impregnation of the HA sol into wood templates. The weight changes of the exacted wood sample with HA gel, phase formation and microstructures evolution of resulting products were investigated by TGA, XRD and SEM. The main weight loss occurred below 600 °C. The biomorphic HA sintered at 1100~1300 °C were three dimensions and connective pores structure, in which the main tracheid pores with diameter of 60~80 μm derived from beech wood template and the small pores with 1~8 μm in the strut walls resulted from the sintering process. Bio-HA faithfully retained the woods porous structure. The method provided a novel candidate for fabricating a porous scaffold suitable for bone tissue engineering applications.

Effect of hyaluronan on periodontitis: A clinical and histological study

Background:Conventional, non-surgical periodontal therapy consists of supra- and subgingival tooth debridement. However, it is a technically demanding procedure and is not always efficient at eradicating all periodontal pathogens and in reducing inflammation. Therefore, local subgingival application of other chemotherapeutic agents may be used as an adjunct to non-surgical therapy. The aim of this study was to investigate the clinical and histological outcomes of local subgingival application of 0.2% hyaluronic acid gel (GENGIGEL®) as an adjunct to scaling and root planing (SRP) in chronic periodontitis patients.Materials and Methods:One hundred and twenty sites were chosen from 26 patients with chronic periodontitis (criteria being periodontal pockets ≥5mm). Experimental sites additionally received HA gel subgingivally at baseline, 1st, 2nd, and 3rd week. Clinical parameters were re-assessed at 4th, 6th, and 12th week. At 4th week recall, a gingival biopsy was obtained from test and control site for histologic examination.Results:Intra-group analysis of all the clinical parameters at all sites from baseline to 4th, 6th, and 12th week showed statistically significant changes. Experimental sites showed statistically significant improvement in Gingival index and Bleeding index at 6th and 12th week when compared with control sites. However, no statistically significant differences were observed in the PPD and RAL between control and experimental sites at 4th, 6th, and 12th week time interval. No statistically significant association was found between the histological grading of the sites that received HA treatment.Conclusion:Subgingival placement of 0.2% HA gel along with SRP provided a significant improvement in gingival parameters. However, no additional benefit was found in periodontal parameters. Histologically, experimental sites showed reduced inflammatory infiltrate, but it was not statistically significant.

Thick Hydroxyapatite Coating on Ti-6Al-4V through Sol-Gel Method

Hydroxyapatite (HA, Ca10(PO4)6(OH)2) powder along with other additives such as P2O5, Na2Co3 and KH2PO4are used for biocompatible coating of Ti-6Al-4V through sol-gel method. An in-house dip coating machine was developed to control dipping and withdrawal rates of the substrate. After passivating of the samples in nitric acid, coating of HA gel was performed followed by sintering in a vacuum furnace. Characterization of the coating layer was evaluated by the XRD and SEM. Imagej software was used for analysis of the data. It was found that increasing the sintering temperature decreases the pore size, resulting in a denser structure of hydroxyapatite and decrease in surface roughness of the coating. High sintering temperatures produced cracked surface of HA due to the α to β transition temperature of Ti and its alloys. HA with coating thickness of about 100 µm free cracks was obtained for sintering temperatures lower than 800 °C.

Lift capabilities of hyaluronic acid fillers

Background: The lift capacity of a filler (ability to oppose deformation and flattening) relates to its suitability for correcting deeper wrinkles and folds, volumizing, and contouring. Lift capacity, considered as a function of both elastic modulus (G′) and gel cohesivity, can be expected to differ among products owing to proprietary manufacturing processes. Objectives: To compare the lift capabilities of 24-mg/ml smooth, cohesive gel fillers (with ∼6% and ∼8% crosslinking) and a 20-mg/ml granular consistency gel filler (∼2% crosslinking). Methods: G′ was measured using a parallel plate rheometer and the products were subjected to a small oscillatory strain. Cohesivity was measured using a linear compression test (quantitative) as well as a dye diffusion test (qualitative). Results: The 24-mg/ml smooth, cohesive gel filler had a lower G′ coupled with lower susceptibility to yield to a given strain versus the 20-mg/ml granular consistency gel filler. Both 24-mg/ml smooth, cohesive gel filler formulations demonstrated greater resistance to deformation in the linear compression test and lower rates of dye diffusion than the 20-mg/ml granular consistency gel filler. Conclusions: The 24-mg/ml smooth, cohesive HA gel fillers achieve a high lift capacity by combining higher cohesivity with lower relative G′ versus the 20-mg/ml granular consistency gel filler.

Longevity of effects of hyaluronic acid plus lidocaine facial filler

A new hyaluronic acid filler containing pre-incorporated 0.3% lidocaine reduces pain and enhances patient comfort. In vitro studies confirm functional equivalence with non-lidocaine-containing products, but only limited data are available on the long-term effects of lidocaine on filler performance in the clinical setting. To investigate whether inclusion of lidocaine impacts the longevity of hyaluronic acid fillers. 60 patients with moderate-severe bilateral nasolabial folds received 24 mg/mL hyaluronic acid with pre-incorporated lidocaine or an equivalent product without lidocaine and were followed-up for up to 76 weeks. Significantly better results were found in favor of HA gel with pre-incorporated lidocaine for physician assessment of injection pain and patient pain assessment after injection (both P < 0.001). Long-term follow-up of patients after almost a year showed that 91% (52/57) of patients had no evidence of facial asymmetry, and investigators confirmed lidocaine had no effect on filler longevity. High levels of patient satisfaction and prolonged benefits due to persistence of the product were noted, with those patients needing additional treatment requiring 'top-up' rather than full re-treatment. The addition of 0.3% lidocaine does not affect product longevity and the small volume required for 'touch-up' also suggests that longevity is maintained.

Hyaluronic acid inhibits the glial scar formation after brain damage with tissue loss in rats

Background Brain tissue scarring (gliosis) was believed to be the major cause of epileptic focus after brain injury, and prevention of scarring could reduce the incidence of seizure. We tried the HA coating onto the cortical brain defect of Spraque-Dawley rats to reduce the marginal glial scarring. Methods A 4 × 2 × 2 mm 3 cortical defect was created in the brain of Spraque-Dawley rats. Three percent HA gel was coated onto the lesion for the experimental groups and normal saline solutions for the control groups. The brain was retrieved 4, 8, and 12 weeks after treatment. The brains were then sectioned and processed for H&E and GFAP staining, and the thickness of the scarring and the number of GFAP+ cells were analyzed. Results The thickness of cutting marginal gliosis was significantly decreased in the HA groups. The 12-week HA group showed the smallest thickness of gliosis, whereas the 12-week control group exhibited the largest thickness of gliosis. The significant difference in the thickness of gliosis was also noted between the HA and the control groups 8 weeks after treatment. The number of GFAP+ cells was also significantly decreased in the HA groups when compared to the respective control group 4, 8, and 12 weeks after the surgery. Conclusion The results support the hypothesis that HA inhibits glial scarring not only by decreasing the thickness of gliosis but also by reducing the number of the glial cells. Furthermore, our results suggest that HA might be used to reduce glial scar formation in central nervous system surgery, which subsequently prevents the post-operation or posttraumatic seizure incidence.

Sol-Gel Synthesis and Characterisation of Nano-sized Hydroxyapatite Powders and Hydroxyapatite/ Poly(D,L-lactide-co-glycolide) Composite Scaffolds

Nano-sized hydroxyapatite (NHA) powders were prepared from calcium nitrate Ca(NO3)2•4H2O and phosphorus pentoxide using a sol–gel approach. The effects of processing parameters on the composition granularity, and morphologies of hydroxyapatite powders were investigated by thermo-gravimetry/differential scanning calorimetry, X-ray diffraction Fourier Transform-infrared spectroscopy, laser particle analysis and transmission electron microscopy. High purity HA powders with particle size of 30–100 nm were obtained by calcining HA gel at 600 °C. The granularity had a narrow distribution and the particles were dispersed well at 600 °C. Hydroxyapatite/poly(D,L-lactide-co-glycolide) (NHA/PLGA) composite scaffolds were prepared by thermally induced phase separation. The compressive strength and water absorption of the scaffolds were investigated. Their mechanical strength increased significantly with the addition of NHA. The composites with 25 wt.% of NHA exhibited good mechanical properties with an average compressive strength of 2.53 MPa. The hydrophilicity increased with the addition of NHA too. NHA/PLGA scaffolds could be a candidate for tissue engineering.

Topical high molecular weight hyaluronan reduces radicular pain post laminectomy in a rat model

Topical high molecular weight hyaluronan reduces radicular pain post laminectomy in a rat model

Topical high-molecular-weight hyaluronan and a roofing barrier sheet equally inhibit postlaminectomy fibrosis

Topical high-molecular-weight hyaluronan and a roofing barrier sheet equally inhibit postlaminectomy fibrosis

Preparation of hoki ( Johnius belengerii) bone oligophosphopeptide with a high affinity to calcium by carnivorous intestine crude proteinase

In the present study, the skeletons discarded from industrial processing of hoki ( Johnius belengerii) were digested by a heterogeneous enzyme extracted from the intestine of a carnivorous fish (also discarded from industrial processing), bluefin tuna ( Thunnus thynnus), in order to utilize the bone in nutraceuticals with a high bioavailability of calcium. The tuna intestine crude enzyme (TICE) could effectively biodegrade the hoki bone matrices composed of collagen, non-collageneous proteins, carbohydrates and minerals. A fish bone phosphopeptide (FBP) containing 23.6% of phoshorus was isolated from the hoki bone hydrolysates degraded by TICE using HA affinity chromatography and gel permeation chromatography. After the FBP, with a molecular mass of 3.5 kDa, was interacted with calcium, 41.1 mg/l of soluble calcium were maintained at 20 mM phosphate buffer (pH 7.8) without the formation of insoluble calcium phosphate. The results provide evidence that the carnivorous fish intestine enzyme (TICE) could degrade the teleost ( J. belengerii) bone, and the fish bone oligophosphopeptide prepared by the enzymatic degradation of the bone could be utilized as a nutraceutical with a potential calcium-binding activity.

Characteristics of hyaluronate-hydroxyethyl acrylate blend gel and release of cationic amphiphilic solutes.

Hyaluronate-hydroxyethyl acrylate blend gel (HA-PHEA) were prepared to modify the brittleness of hyaluronate gel (HA) and the characteristics of HA-PHEA gel were compared with those of HA and polyhydroxyethyl acrylate (PHEA) gels. These gels were high in water content and transparent. HA-PHEA gel was improved in viscoelastic properties due to the elasticity and the high affinity with water of PHEA, and the drying-swelling cycles became reversible. The effective charge densities theta of the gels estimated from membrane potentials were -0.002, -0.008 and 0 mol dm(-3) for HA-PHEA, HA and PHEA gels. Effects of electro- static and nonelectrostatic interactions on absorptions and releases were studied using sodium benzoate (NaBA) as an anionic solute, and methylene blue (MB), chlorpromazine (CPHCl) and benzethonium chloride (BZTCl) as cationic solutes, in which CPHCl and BZTCl are cationic amphiphilic solutes. The releases of MB, CPHCl and BZTCl from HA-PHEA and HA gels were suppressed comparing with those of NaBA. By adding salts, the releases of MB and CPHCl were enhanced but those of BZTCl were suppressed due to enhancement of the intra- and intermicelle formation. In the releases of the cationic solutes from HA-PHEA gel, electrostatic and nonelectrostatic interactions with HA were found to play important roles. Behaviors of the releases from HA-PHEA gel were found to possess the features of HA gel.

Cross-linked hyaluronate hydrogel prevents adhesion formation and reformation in mouse uterine horn model.

The aim of this study was to evaluate the efficacy of cross-linked hyaluronate hydrogel (HA gel) as an adjuvant for postoperative adhesion prevention, in a mouse uterine horn model. In experiment 1 uterine horns were abrased with iodine. HA gel was applied to the injured surface before closure in the treatment group. In experiment 2, after injuring the uterine horns, three stitches were placed at equal distances around the uterine horns to appose the injured medial surfaces of the two horns during healing. HA gel was inserted between the uterine horns in the treatment group. In experiment 3 prevention of adhesion reformation was assessed. After lysis of adhesions that were induced as in experiment 2, HA gel was introduced between the serosal surfaces of apposing uterine horns. Untreated animals served as controls in each experiment. Statistical analysis was carried out using Student's t-test. The adhesion score was significantly lower in the HA gel group on the 14th day compared with controls in all the experiments: in experiment 1, 0.3 +/- 0.4 versus 1.7 +/- 1.2; in experiment 2, 0.9 +/- 1.0 versus 2.6 +/- 0.5; and in experiment 3, 1.5 +/- 0.9 versus 2.2 +/- 0.6 respectively. Cross-linked HA gel significantly reduced de-novo adhesions (P< 0.03) and adhesion reformation (P < 0.03).

Effects of gel processing on the properties of humic acid isolated from the alga Pilayella littoralis : A humic acid aerogel

Humic acid in the live alga Pilayellalittoralis was isolated as an aqueous gel by a standard sequential extraction method augmented with removal of alginic acid. Portions of the aqueous gel were (1) vacuum oven dried at 40 °C, (2) freeze freeze dried after cooling in liquid N2, and (3) dried with supercritical fluid CO2 after substitution of water in the gel with acetone. This paper compares the analytical and spectral properties of the products with compost derived HA and reports significant differences in their surface areas, packing densities, water retention, solute sorption and metal binding properties. The results are discussed in terms of different product morphologies determined by scanning electron microscopy. The aerogel obtained by supercritical fluid CO2 drying of an HA gel from Pilayella has the highest surface area (188 m2 g-1) reported for a humic acid.

Neurologic Disorders in Saudi Children

Neurologic Disorders in Saudi Children

Outpatient Neurological Practice in Saudi Arabia and its Implications for Education in Neurology

Outpatient Neurological Practice in Saudi Arabia and its Implications for Education in Neurology

Natural heterogeneity of shape, infectivity and protein composition in an influenza A (H3N2) virus preparation.

Influenza A (X31) virus was purified over a zonal sucrose gradient. The resulting gradient fractions were examined by electron microscopy, HA and infectivity titrations and gel electrophoresis. The fractions containing a homogeneous suspension of spherical particles had the highest infectivity per amount of viral protein and a much higher HA:M ratio than the unfractionated preparation. These results explain differences in the proportions of HA and M protein we have reported elsewhere on monodisperse virus suspensions compared with earlier measurements on crude suspensions.