Acid Resistance Stability Research Articles

A Remineralizing and Antibacterial Coating for Arresting Caries.

Dental caries is a dynamic disease induced by the unbalance between demineralization of dental hard tissues caused by biofilm and remineralization of them; however, although various effective remineralization methods have been well documented, it is a challenge to reestablish the balance by enhancing remineralization alone while ignoring the antibacterial therapy. Therefore, the integration of remineralizing and antibacterial technologies offers a promising strategy to halt natural caries progression in clinical practice. Here, the conception of interrupting dental caries (IDC) was proposed based on the development of dual-functional coating with remineralizing and antibacterial properties. In this study, bovine serum albumin (BSA) loaded octenidine (OCT) successfully to form a BSA-OCT composite. Subsequently, through fast amyloid-like aggregation, the phase-transited BSA-OCT (PTB-OCT) coating can be covered on teeth, resin composite, or sealant surfaces in 30 min by a simple smearing process. The PTB-OCT coating showed satisfactory effects in promoting the remineralization of demineralized enamel and dentin in vitro. Moreover, this coating also exerted significant acid-resistance stability and anti-biofilm properties. Equally importantly, this coating exhibited promising abilities in reducing the microleakage between the tooth and resin composite in vitro and preventing primary and secondary caries in vivo. In conclusion, this novel dual-functional PTB-OCT coating could reestablish the balance between demineralization and remineralization in the process of caries, thereby potentially preventing or arresting caries.

A novel rapidly mineralized biphasic calcium phosphate with high acid-resistance stability for long-term treatment of dentin hypersensitivity.

Treating dental hypersensitivity (DH) rapidly and maintaining long-term effectiveness remains challenging. We aimed to address this problem by fabricating a novel rapidly mineralized biphasic calcium phosphate (RMBCP), which could rapidly elicit mineralization to form hydroxyapatite (HA) and perform excellent acid-resistant stability, thus effectively blocking the exposed dental tubules and protecting them from acid attack. RMBCP was firstly synthesized by precisely adjusting the molar ratio of acetic acid and calcium hydroxide and characterized by X-ray diffraction (XRD), X-ray fluorescence microprobe (XRF), Fourier-transform infrared (FTIR) spectrometer, scanning electron microscope (SEM), and transmission electron microscope (TEM). Subsequently, using a commercialized desensitizing agent, 45S5 bioglass (BG), as the control group, the mineralization performance of RMBCP was investigated in simulated body fluid (SBF), Dulbecco's modified eagle medium (DMEM), and even slightly acidic artificial saliva (pH=6.6). Moreover, the biocompatibility of RMBCP was studied. Finally, the tubule occlusion effect and acid-resistant stability of RMBCP were evaluated in vitro and in vivo. The rapid mineralization behavior of RMBCP could easily adhere to the dentin surface and block the dentinal tubules completely in vitro and in vivo within 7days. RMBCP performed high acid-resistant stability to maintain the long-term therapeutic effect of DH treatment. Developing novel bioactive calcium phosphate materials with the ability to trigger mineralization for HA formation rapidly will be an effective strategy for the long-term treatment of dentin hypersensitivity.

Functionalized chitosan-magnetic flocculants for heavy metal and dye removal modeled by an artificial neural network

In this study, an amphoteric magnetic chitosan (CS)-based flocculant MFe3O4@CS-g-PIA was prepared from CS, Fe3O4, and itaconic acid (IA), and its apparent morphology and characteristic structure were systematically studied. The flocculation performance and mechanism of the fabricated material were also investigated in different pollution systems, and the effects of total monomer concentration, m(CS):m(IA), IA pre-neutralization degree, reaction temperature, reaction time, and initiator concentration on the synthesis of MFe3O4@CS-g-PIA were studied. Characterization results showed that MFe3O4@CS-g-PIA forms a three-dimensional network with excellent magnetic induction. The optimal removal rates of Cu(II) and Disperse Blue 56 (DB56; 90.2% and 97.0%, respectively) were obtained under the conditions of 150 mg·L−1 MFe3O4@CS-g-PIA, pH 6.0, and 300 rpm stirring speed. MFe3O4@CS-g-PIA maintained removal rates of over 80.0% for Cu(II) and DB56 after five consecutive cycles of regeneration/flocculation and demonstrated excellent acid resistance stability. Changes in the particle size distribution, fractal dimensions, and zeta potentials of the flocs indicated that the relevant flocculation mechanism involves the synergistic functions of chelation, charge neutralization, and adsorption bridging. An artificial neural network model was finally established on the basis of the experimental flocculation data to predict the removal rates of Cu(II) (R = 0.97) and DB56 (R = 0.98) accurately.

In vitro evaluation of enteral tube administration of lansoprazole orally disintegrating tablets

Lansoprazole orally disintegrating tablets (ODTs) can be administered orally or through a nasogastric (NG) tube for patients who are unable to swallow. In addition, off-label administration through gastrostomy (G) or jejunal (J) tubes has been reported. The purpose of this study was to develop in vitro methods to assess the risk of clogging during administration of two lansoprazole ODTs through enteral feeding tubes. Feeding tubes of various compositions and geometries were selected for testing. Disintegration, sedimentation, percent recovery, acid phase dissolution testing, and particle size distribution measurements were performed. The results indicated that G tubes had the greatest risk of clogging compared to NG and J tubes. In addition, larger particles and an increased amount of insoluble excipients observed in Product B resulted in more irreversible enteral tube clogging than compared to Product A. The geometry and design of the tube also had an impact on the amount of lansoprazole recovered after enteral tube administration. Lansoprazole ODTs demonstrated acid resistance stability regardless of the water used for suspension. The in vitro methods discussed in this work could be used to evaluate in vitro equivalence and to assess the risk of delivering a drug product through an enteral feeding tube.

Granular reduced graphene oxide/Fe3O4 hydrogel for efficient adsorption and catalytic oxidation of p-perfluorous nonenoxybenzene sulfonate

The catalytic performance of Fe3O4/reduced graphene oxide (Fe3O4/rGO) nanocomposite makes it attractive for the removal of emerging pollutants from water, but the combination of its efficient adsorption and degradation of per- and polyfluoroalkyl substances has not been studied. Here we report the optimal granular Fe3O4/rGO with high thermal and acid resistance stability through controlling its self-assembly for the adsorption and degradation of sodium p-perfluorous nonenoxybenzene sulfonate (OBS) from water. The maximum adsorption capacity for OBS was calculated to be 362.4 μmol/g according to Langmuir fitting. Electrostatic, π-π and hydrogen bonding interactions were involved in OBS adsorption, and the quaternary N in Fe3O4/rGO was a key adsorption site. The efficiency of the utilization of free radicals generated in Fenton-like and persulfate (PS) systems increased with the increase of OBS adsorbed onto the Fe3O4/rGO, while the increase of OBS amount adsorbed on Fe3O4/rGO would casue a slow OBS removal in the adsorption-degradation process due to the slow adsorption process. The Fenton-like oxidation was more efficient for OBS removal than PS oxidation. The spent Fe3O4/rGO was able to be reused in the Fenton-like system at least ten times, while the OBS removal in the PS reaction system was reduced to 47.8 % after six reuse cycles.

Characterization of Acidified Opal Shale and Dynamic Adsorption of Toluene

Different kinds of acidified opal shale powders were obtained through the activation of natural opal shale powders with different concentrations of sulfuric acid. The natural opal shale and different acidified opal shale materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. It was found that the opal shale has good acid resistance stability. When the sulfuric acid concentration reaches a high concentration of 6 mol/L in the acidification treatment, the opal shale can still maintain its original main silica structure. Natural opal shale is a typical mesoporous material with a BET specific surface area of about 12 nm, but it also contains a small amount of micropores and macropores. Appropriate acid treatment can increase the specific surface area. An excessively high concentration of acid that exceeds 6 mol/L sulfuric acid can destroy the main structure of the cation, resulting in a decrease in the specific surface area. In this paper, the adsorptive breakthrough curves for toluene, dynamic saturated adsorption capacity and other gas adsorption performances of these materials were studied. Finally, the best adsorption material was the 2 mol/L sulfuric acid acidified opal shale at 333K under stirring for 4 hours.

In Vitro Evaluation of Nasogastric Tube Delivery Performance of Esomeprazole Magnesium Delayed-Release Capsules

Enteral feeding tubes are used to deliver food or drugs to patients who cannot swallow. To deliver delayed-release drugs that are formulated as enteric coated granules to these patients via feeding tubes requires that they be suspended in water before administration. Importantly, the suspension of enteric granules in water of varying pH can cause damage to the enteric coating and affect the bioavailability of the drug. Here, analytical methods for testing acid resistance stability and particle size distribution (PSD) of esomeprazole granules were used to monitor the integrity of the granule enteric coating after water pretreatment and delivery through an oral syringe and nasogastric (NG) tube. Granules from esomeprazole magnesium delayed-release capsules were transferred to an oral syringe, suspended in water, and delivered on the bench through an NG tube. Subsequently, acid resistance stability (i.e., the amount of drug released after 2-h acid dissolution) was determined via high-performance liquid chromatography, and the PSD were measured with a laser diffraction system. All the granules demonstrated acid resistance stability when the granules were delivered immediately (0 min incubation) through the oral syringe and NG tube. In contrast, some granules demonstrated significant drug release during acid exposure after a 15-min incubation period which mimics a possible delay in delivery of the drug from the syringe by the caregiver. A bimodal PSD was observed with these granules, which was attributed to debris from damaged enteric coating and particle agglomeration. The methods developed in this study could be used to distinguish batches with suboptimal product quality for delivery using NG tubes and to confirm the substitutability of generic drug products for this alternative route of administration.

Esomeprazole compared with lansoprazole for maintaining healed erosive esophagitis in patients with hiatus hernia

Enteral feeding tubes are used to deliver food or drugs to patients who cannot swallow. To deliver delayed-release drugs that are formulated as enteric coated granules to these patients via feeding tubes requires that they be suspended in water before administration. Importantly, the suspension of enteric granules in water of varying pH can cause damage to the enteric coating and affect the bioavailability of the drug. Here, analytical methods for testing acid resistance stability and particle size distribution (PSD) of esomeprazole granules were used to monitor the integrity of the granule enteric coating after water pretreatment and delivery through an oral syringe and nasogastric (NG) tube. Granules from esomeprazole magnesium delayed-release capsules were transferred to an oral syringe, suspended in water, and delivered on the bench through an NG tube. Subsequently, acid resistance stability (i.e., the amount of drug released after 2-h acid dissolution) was determined via high-performance liquid chromatography, and the PSD were measured with a laser diffraction system. All the granules demonstrated acid resistance stability when the granules were delivered immediately (0 min incubation) through the oral syringe and NG tube. In contrast, some granules demonstrated significant drug release during acid exposure after a 15-min incubation period which mimics a possible delay in delivery of the drug from the syringe by the caregiver. A bimodal PSD was observed with these granules, which was attributed to debris from damaged enteric coating and particle agglomeration. The methods developed in this study could be used to distinguish batches with suboptimal product quality for delivery using NG tubes and to confirm the substitutability of generic drug products for this alternative route of administration.