Efficacy of the stannous ion and a biopolymer in toothpastes on enamel erosion/abrasion

Objectives

Sn²⁺ has promising erosion-inhibiting properties in solutions, but little is known about respective effects in toothpastes. In addition, biopolymers might have protecting potential. Aim of this study was to investigate the effects of Sn²⁺ in toothpastes and of a biopolymer (chitosan) added to a Sn²⁺ formulation on erosion/abrasion.

Methods

Enamel samples were subjected to cyclic erosion procedures (10 days; 0.50% citric acid, pH 2.5; 6× 2 min/day), and brushing (2× 15 s/day, load 200 g) during immersion in slurries (2 min). The toothpastes were NaF formulations (NaF/1, NaF/2, NaF/3) and Sn²⁺ formulations (NaF/SnCl₂, AmF/SnF₂, AmF/NaF/SnCl₂) and AmF/NaF/SnCl₂ + 0.5% chitosan.Declared concentrations of active ingredients in toothpastes were 1400–1450 μg/g F⁻ and 3280–3500 μg/g Sn²⁺. Negative controls were erosion only and placebo, positive control was a SnF₂ gel. Tissue loss was quantified profilometrically, Sn on enamel surfaces was measured by energy dispersive X-ray spectroscopy.

Results

Loss values (μm) for erosion only and placebo were 14.4 ± 4.5 and 20.2 ± 3.8, respectively, and 4.6 ± 1.9 for the positive control (p ≤ 0.001 each compared to erosion only). The other loss values were: NaF/1 16.5 ± 3.0, NaF/2 14.0 ± 2.7, NaF/3 12.6 ± 3.9, NaF/SnCl₂ 14.7 ± 5.1, AmF/SnF₂ 13.5 ± 4.8, AmF/NaF/SnCl₂ 12.4 ± 4.2, AmF/NaF/SnCl₂ + chitosan 6.6 ± 3.5 (except NaF/1 all p ≤ 0.01 compared to placebo). AmF/NaF/SnCl₂/chitosan was more effective than all other toothpastes (p ≤ 0.01 each). Sn on the enamel surface ranged between 1.3 ± 0.3 and 2.8 ± 0.04 wt.% with no obvious relationship with efficacy.

Conclusions

The NaF and Sn²⁺ toothpastes without chitosan exhibited similar anti-erosion and abrasion-prevention effects. The experimental Sn²⁺ formulation with chitosan revealed promising results similar to those of the positive control.

Clinical significance

NaF toothpastes offer a degree of protection against erosion/abrasion, which is likely sufficient for most subjects with average acid exposures. For patients with initial erosive lesions, however, more effective toothpaste is desirable. The combination of Sn²⁺ and a biopolymer appears promising in this context.     

Synthesis,characterization, and biological activity of cross-linked chitosan biguanidine loaded with silver nanoparticles

Chitosan biguanidine hydrochloride (ChG) and glutaraldehyde cross-linked chitosan biguanidine (CChG) were synthesized and characterized by Fourier transform infrared spectroscopy, ¹H NMR and ¹³C NMR, X-ray diffraction, scanning electron microscopy (SEM) and thermal analyses (TGA and DTA). The results showed that ChG and CChG had a more amorphous structure than that of chitosan, and their thermal stability were slightly lower than that of chitosan. Colloidal silver nanoparticles (AgNPs) were prepared using borohydride reduction method and then investigated as fillers in partially cross-linked chitosan biguanidine. The obtained nanoparticles were uniform and spherical with average size of 9.6 ± 0.5 nm. The prepared CChG/AgNPs composites were characterized for their morphology, thermal properties, cytotoxicity and antimicrobial activity. The SEM images showed that the AgNPs are well imbedded in the CChG matrix. The thermal stability of CChG was improved with incorporation of AgNPs. The CChG and CChG/AgNPs showed less cytotoxicity to breast cancer cells (MCF-7). Compared with chitosan and CChG, the ChG and CChG/AgNPs showed better antimicrobial activity against Streptococcus pneumoniae and Bacillus subtilis as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum as fungi.     

In-vitro and in-vivo cytotoxicity and efficacy evaluation of novel glycyl-glycine and alanyl-alanine conjugates of chitosan and trimethyl chitosan nano-particles as carriers for oral insulin delivery

Purpose

The aim of this research work was to explore the possibility of providing multifunctional oral insulin delivery system by conjugating several types of dipeptides on chitosan and trimethyl chitosan to be used as drug carriers.

Particle agglomeration of chitosan–magnesium aluminum silicate nanocomposites for direct compression tablets

Exfoliated nanocomposites of chitosan-magnesium aluminum silicate (CS-MAS) particles are characterized by good compressibility but poor flowability. Thus, the aims of this study were to investigate agglomerates of CS-MAS nanocomposites prepared using the agglomerating agents water, ethanol, or polyvinylpyrrolidone (PVP) for flowability enhancement and to evaluate the agglomerates obtained as direct compression fillers for tablets. The results showed that the addition of agglomerating agents did not affect crystallinity, but slightly influenced thermal behavior of the CS-MAS nanocomposites. The agglomerates prepared using water were larger than those prepared using 95% ethanol because high swelling of the layer of chitosonium acetate occurred, allowing formation of solid bridges and capillary force between particles, leading to higher flowability and particle strength. Incorporation of PVP resulted in larger agglomerates with good flowability and high strength due to the binder hardening mechanism. The tablets prepared from agglomerates using water showed lower hardness, shorter disintegration times and faster drug release than those using 95% ethanol. In contrast, greater hardness and more prolonged drug release were obtained from the tablets prepared from agglomerates using PVP. Additionally, the agglomerates of CS-MAS nanocomposites showed good carrying capacity and provided desirable characteristics of direct compression tablets.     

壳聚糖的化学改性及其衍生物的抗氧化活性研究进展

摘 要壳聚糖是一种天然无毒的生物聚合物,主要经甲壳素的脱乙酰作用制得,具有良好的生物相容性、独特的抗氧化活性及生物可降解性等。由于壳聚糖在中性和碱性溶液中溶解性较差,其应用受到了一定限制,通常对其进行多种改性,拓宽其应用范围,提高其利用价值。近年来具有抗氧化能力的壳聚糖及壳聚糖衍生物表现出了优越的医用价值。本文综述了几种壳聚糖常用的改性方法,并介绍了壳聚糖及其衍生物作为抗氧化剂应用的研究进展。     

Effect of polymer type on characteristics of buccal tablets using factorial design

A two factor three level factorial design was used to investigate the effects of carbopol and cationic hydrophilic polymers which have a common use in buccal drug formulations. Statistical models with interaction terms were derived to evaluate influence of carbopol (X1) and chitosan (X2) on tablet disintegration (Y1) and dissolution (Y2), mechanical properties (Y3), swelling (Y4). Tablet disintegration studies were carried out using two different pH environments within buccal region pH limits and also two different commonly used dissolution methods for buccal tablets were also investigated to compare the effect of polymer type on dissolution. Polymer type and ratio affect the characteristics of the buccal tablets due to their different physicochemical behavior at buccal pH. Also significant variances between dissolution profiles for buccal tablets, using either USP Paddle or flow through cell methods were found. These results indicate that both polymer type and ratio as well as combination of them effects the drug behavior in different ways.     

Chitosan-based zinc oxide nanoparticle for enhanced anticancer effect in cervical cancer: A physicochemical and biological perspective

In this study, chitosan-assembled zinc oxide nanoparticle (CZNP) was successfully prepared for evaluated for its anticancer efficacy against cervical cancer cells. The CZNP particles were nanosized and spherical in shape. The zinc oxide nanoparticle (ZNP) and CZNP showed significant cytotoxicity in cervical cancer cells in a concentration-dependent manner. Results showed that the enhanced cytotoxicity was mainly attributed to the reactive oxygen species (ROS) generation in the cancer cells. The apoptosis assay further revealed that apoptosis was the main reason behind the cell killing effect of the zinc oxide nanoparticles. The apoptosis was further confirmed by the nuclear chromatin assay. Live dead assay showed increased red fluorescent cell for CZNP treated cancer cells. Overall, metal oxide present in nanoparticulate dimensions will be advantageous in imparting the cytotoxicity to cervical cancer cell.     

星点设计-效应面法优化壳聚糖微球对凝血酶的固定化作用研究

目的 考察壳聚糖微球对凝血酶的固定化作用。方法 本研究以壳聚糖微球为载体,以戊二醛为交联剂将凝血酶固定于空白微球上,以固定化凝血酶的活性回收率为指标,采用星点设计-效应面法优化固定凝血酶的条件。结果 试验结果表明,壳聚糖微球固定凝血酶的最优条件是：凝血酶浓度69.32 U·mL^-1、戊二醛浓度0.18%、固定化时间1.88 h、固定化pH 7.08,凝血酶的活性回收率为81.55 %。结论 壳聚糖微球对凝血酶的固定化效果良好。     

Microfluidic one-step synthesis of Fe3O4-chitosan composite particles and their applications

This paper demonstrates a simple and easy approach for the one-step synthesis of Fe₃O₄-chitosan composite particles with tadpole-like shape. The length and diameter of the particles were adjustable from 638.3 μm to ca. 798 μm (length), and from 290 μm to 412 μm (diameter) by varying the flow rate of the dispersed phase. Mitoxantrone was used as the model drug in the drug release study. The encapsulation rate of the drug was 71% for chitosan particles, and 69% for magnetic iron oxide-chitosan particles, respectively. The iron oxide-chitosan composite particles had a faster release rate (up to 41.6% at the third hour) than the chitosan particles (about 24.6%). These iron oxide-chitosan composite particles are potentially useful for biomedical applications, such as magnetic responsive drug carriers, magnetic resonance imaging (MRI) enhancers, in the future.