Impact of Dentin Substrate Modification with Chitosan-Hydroxyapatite Precursor Nanocomplexes on Sealer Penetration and Tensile Strength

IntroductionThe purpose of this study was to evaluate the effect of dentin conditioning with chitosan-hydroxyapatite precursor (C-HA) nanocomplexes on the depth of tricalcium silicate sealer penetration into dentinal tubules and ultimate tensile strength (UTS).Methodssurface charge and size distribution for C-HA nanocomplex formulation was evaluated followed by bioactivity assessment of standardized films of C-HA nanocomplexes (n = 15) incubated in simulated body fluid. Mineralization potential was assessed with X-ray diffraction and Fourier-transform infrared spectroscopy, whereas scanning electron microscopy was used for ultrastructural evaluation. Static water contact angles and UTS were measured on dentin discs (n = 2/group) and dentin beams (n = 10/group) treated with/without sodium hypochlorite/EDTA and C-HA nanocomplex conditioning. In phase 2, the depth of sealer penetration after C-HA nanocomplex conditioning was evaluated using fluorescent imaging (n = 12/group). The percent area penetration and mean/maximum penetration depth were calculated at 4- and 6-mm levels from the root apex. Data from contact angle measurements, mechanical testing, and penetration assessment parameters were subjected to the independent samples t test with a significance level set at P < .05.ResultsA formulation of C-HA nanocomplexes (2 mg/mL) was chosen as a polyanionic, hydrophilic, nonaggregating concentration having bioactivity potential established through the formation of phosphate/carbonate bonds and the crystalline nature of the formed minerals. A significantly lower contact angle and higher UTS were registered for the C-HA nanocomplex–conditioned group (P < .05). Statistically significant (P < .05) greater sealer penetration was recorded at the 4-mm level for all assessment parameters and percent area penetration at 6 mm for the C-HA nanocomplex group.ConclusionsC-HA nanocomplex conditioning enhances dentin surface wettability to facilitate greater tricalcium silicate sealer penetration and UTS of dentin.     

Grafting of gallic acid onto chitosan nano particles enhances antioxidant activities in vitro and protects against ochratoxin A toxicity in catfish (Clarias gariepinus)

This study aimed to prepare and characterize enzymatic modified chitosan nanoparticles (CSNPs) with gallic acid (GA) or octyl gallate (OG) to optimize its potential in human application and to evaluate their protective role against ochrtoxin A (OTA) toxicity in catfish. The modified CSNPs have average size around 90 nm with positive charge and high scavenging activity especially GA-CSNPs. In the in vivo study, catfish were divided into 8 groups and treated for 3 weeks as follow: the control group, OTA-treated group (1 mg/kg b.w.), the groups treated with CSNPs, GA-CSNPs or OG-CSNPs (280 mg/kg b.w.) anole or in combination with OTA. Blood, liver and kidney samples were collected for different analyses. OTA induced a significant biochemical disturbances accompanied with oxidative stress in liver and kidney, histological changes and increase DNA fragmentation in the kidney. Co-treatment with OTA plus the different CSNPs resulted in a significant improvement in all tested parameters and histological picture of the kidney. This improvement was more pronounced in the group treated with GA-CSNPs. It could be concluded that grafting of GA or its ester improved the properties of CSNPs. Moreover, GA-CSNPs showed strong scavenging properties than OG-CSNPs due to the blocking of carboxyl groups responsible of the scavenging activity in OG.     

Synthesis and Charactersiation of Chitosan conjugate; Design and Evaluation of Membrane Moderated Type Transdermal Drug Delivery System

The purpose of the present research investigation was to synthesis, characterisation of chitosan conjugates and its effect on drug permeation from transdermal rate controlling membrane. Chitosan conjugate was synthesised by conjugation with thioglycolic acid. The prepared chitosan conjugate was characterised by determining the charring point, Fourier transmission-infrared and differential scanning calorimetric analysis. The rate controlling membranes were prepared by various proportions of chitosan and chitosan conjugate, to moderate drug permeation through rate controlling membrane. The membrane moderated transdermal system consists of reservoir to hold the drug gel was prepared by 20% w/v ethylcellulose with a cavity in its center. An impermeable backing layer was prepared by 2% w/v ethylcellulose. Gel consists of carvedilol was prepared by sodium alginate and sodium carboxymethylcellulose in ethanol:water solvent system The rate controlling membranes prepared were evaluated by various parameters like thickness, folding endurance, swelling index, moisture content, moisture uptake, water vapor transmission rate, tensile strength test, measurement of gel strength, in vitro permeation study, ex vivo permeation study, compatibility study using differential scanning calorimetry and stability studies. All physical parameters evident that prepared membranes have good folding endurance and sufficient tensile strength. As the proportion of chitosan conjugate increases in membrane swelling index, moisture content, moisture uptake and permeability coefficient increases. The gel strength of chitosan conjugate was considerable less compared with chitosan.     

壳聚糖复合药膜的研制及实验研究

目的 :制备壳聚糖口腔复合膜 ,并通过建立口腔溃疡的动物模型 ,观察复合药膜对实验性口腔溃疡愈合的影响。方法 :选择壳聚糖作为膜载体 ,加入芦荟、表皮生长因子 (EGF)等药物制备口腔复合膜 ,用动物实验验证复合膜的疗效。结果 :(1)复合膜厚约 0 .5mm ,复合膜每平方厘米含水溶性壳聚糖 0 .0 0 7g、芦荟全叶冻干粉 0 .0 5 1g、EGF 40IU、丁卡因 0 .5 3 3mg。(2 )不同时间复合膜组溃疡面积均小于对照组 (P <0 .0 5 ) ;平均愈合速度复合膜组快于其他组 (P <0 .0 5 ) ;水肿充血程度明显好于对照组 ;炎性细胞在各个时间点复合膜组均少于对照组 (P <0 .0 5 ) ;成纤维细胞高于对照组 (P <0 .0 5 )。结论 :壳聚糖复合药膜可明显促进实验性口腔溃疡愈合 ,具有一定的应用前景 ,但作用机制有待进一步阐明。     

Release phenomena of insulin from an implantable device composed of a polyion complex of chitosan and sodium hyaluronate

An implant controlled-release system for protein drug delivery based on a polyion complex device composed of chitosan (CS) and sodium hyaluronate (HA) was investigated. The conditions which generated the greatest amount of the polyion solid complex were studied to ascertain the formation of polyion complex between CS and HA. The greatest amount of the polyion complex was formed at the weight ratio of 3 to 7 (CS:HA) at pH 3.5. Furthermore, the CS–HA pellets were prepared and then drug release from CS–HA pellets was evaluated using insulin as a model drug. The results demonstrated that the insulin release from CS–HA pellets was markedly influenced by both the change in the polymer mixing ratio and the total pellet weight, whereas the compression pressure did not affect the release significantly. An artificial neural network (ANN) and biharmonic spline interpolation (HSI) were employed to predict the actual relation between causal factors and the release rate constant of insulin. Although both the ANN and HSI successfully represented a non-linear relationship between the formulation factors and the release rate constant, HSI methodology gave a better estimation than that of the ANN.     

负载重组人骨形态发生蛋白-2壳聚糖纳米微球的制备及异位成骨活性研究

目的 制备负载重组人骨形态发生蛋白-2(rhBMP-2)的壳聚糖纳米微球,并考察其成骨活性. 方法 应用离子交联法制备空白壳聚糖纳米微球和rhBMP-2壳聚糖纳米微球,应用透射电镜观察微球的形态,激光粒径分析仪测定其粒径的分布,检测其载药量、包封率及累积释药率.取24只SD大鼠,随机分为4组,每组6只.以无菌手术分别在大鼠左侧股部建立肌袋.A组大鼠肌袋内植入rhBMP-2壳聚糖纳米微球(含rhBMP-2 1 mg),B组大鼠肌袋内植入rhBMP-2 1 mg,C组大鼠肌袋内植入空白壳聚糖纳米微球,D组大鼠肌袋内不做任何处理.评估rhBMP-2壳聚糖纳米微球的成骨活性.结果离子交联法制备的壳聚糖纳米微球球形规整、分散均匀,微球平均粒径为230.0 nm,分布较集中,包封率为66.87％±4.58％,载药率为(33.44±2.29) μg/mg.A、B、C、D组的ALP活性平均分别为(1.94±0 35)、(1.48±0.56)、(0.20±0.07)及(0.18±0.06) kat/g,差异有统计学意义(F=42.959,P=0.000),A、B组明显高于C、D组,且A组高于B组.4组钙含量平均分别为(5.20±1.42)、(3.80±1.40)、(0.19±0.08)、(0.20±0.08)μg/mg,差异有统计学意义(F=39.242,P=0.000),A、B组明 显高于C、D组,且A组高于B组. 结论 离子交联法可成功制备出均一的rhBMP-2壳聚糖纳米微球,该微球具有良好的载药性能和缓释性能,且其骨诱导活性优于单纯rhBMP-2.     

纳米羟基磷灰石/壳聚糖复合支架修复兔股骨髁临界性骨缺损的实验研究

目的 探讨纳米羟基磷灰石(nHA)/壳聚糖(CS)复合支架修复兔股骨髁临界性骨缺损的能力. 方法 取44只健康成年新两兰大白兔,于兔左侧股骨外侧髁建立临界性骨缺损(直径为6mm、深为10 mm)模型,随机分为3组:实验组(n=20):骨缺损处植入nHA/CS复合材料;对照组(n＝20):骨缺损处植入单纯CS;空白组(n=4):骨缺损处旷置,不植入任何材料.术后8、12周取材行大体观察、X线摄片、显微CT扫描及组织学观察,比较各组骨缺损的修复能力. 结果 术后12周X线片显示实验组骨缺损修复良好,骨皮质连续;对照组缺损区明显缩小,两断端不连接;空白组缺损区无明显骨痂生成.实验组和对照组Lane-Sandhu X射线评分平均分别为(10.18±0.98)、(8.90±0.99)分,两组比较差异有统计学意义(t=6.858,P=0.000).显微CT扫描显示:实验组骨缺损基本完全修复,股骨髁外形恢复正常;对照组骨缺损空腔大部分为新生骨组织填充,缺损区仍留有缺损;空白组骨缺损基本无修复.实验组和对照组CT值平均分别为(256.1±26.8)、(169.2±25.4)Hu,两组比较差异有统计学意义(t=4.711,P=0.003).术后12周组织学观察显示:实验组可见大量新生骨小梁,新生骨质与周围骨床之间无明显分界线;对照组可见骨缺损为剩余材料与纤维组织充填;空白组骨缺损区均被少量纤维组织充填. 结论 nHA/CS复合材料较单纯CS能更好地促进兔股骨髁临界性骨缺损的修复,是一种很有应用前景的组织工程修复材料.     

Efficacy study of two novel hyaluronic acid-based formulations for viscosupplementation therapy in an early osteoarthrosic rabbit model

Viscosupplementation (VS) is a therapy for osteoarthrosis (OA) consisting of repetitive intra-articular injections of hyaluronic acid (HA). It is known to be clinically effective in relieving pain and increasing joint mobility by restoring joint homeostasis. In this study, the effects of two novel HA-based VS hydrogel formulations were assessed and challenged against a pure HA commercial formulation for the first time and this in a rabbit model of early OA induced by anterior cruciate ligament transection (ACLT). The first formulation tested was a hybrid hydrogel composed of HA and reacetylated chitosan, a biopolymer considered to be chondroprotective, assembled thanks to an ionic shielding. The second formulation consisted of a novel HA polymer grafted with antioxidant molecules (HA-4AR) aiming at decreasing OA oxidative stress and increasing HA retention time in the articulation.ACLT was performed on rabbits in order to cause structural changes comparable to traumatic osteoarthrosis. The protective effects of the different formulations were observed on the early phase of the pathology in a full randomized and blinded manner. The cartilage, synovial membrane, and subchondral bone were evaluated by complementary investigation techniques such as gross morphological scoring, scanning electron microscopy, histological scoring, and micro-computed tomography were used.In this study, ACLT was proven to successfully reproduce early OA articular characteristics found in humans. HA and HA-4AR hydrogels were found to be moderately protective for cartilage as highlighted by μCT. The HA-4AR was the only formulation able to decrease synovial membrane hypertrophy occurring in OA. Finally, the hybrid HA-reacetylated chitosan hydrogel surprisingly led to increased subchondral bone remodeling and cartilage defect formation. This study shows significant effects of two innovative HA modification strategies in an OA rabbit model, which warrant further studies toward more effective viscosupplementation formulations.     

Chitosan based micro- and nanoparticles for colon-targeted delivery of vancomycin prepared by alternative processing methods

The aim of this work was to prepare chitosan (CH) based particulate formulations for colon delivery of vancomycin (VM). Chitosan microparticles (MPs) and nanoparticles (NPs) loaded with VM were prepared using different CH/tripolyphosphate (TPP) molar ratios and different technological processes. In particular, nanoparticles were prepared by ionic gelation and freeze-drying to recover these particles, or, alternatively, by spray-drying method. Microparticles were prepared using a different spray-dryer. Micro- and nanoparticles were characterized in terms of size distributions by photon correlation spectroscopy (PCS), while encapsulation and drug loading efficiencies were studied using a dialysis method. Fourier Transform Infrared Spectroscopy (FT-IR) was employed to determine the surface composition of the micro- and nanoparticles respectively, and the morphologies of the developed systems were studied by scanning electron microscopy (SEM). Water uptake as well as drug release profiles were also measured. Antibacterial activity against Staphylococcus aureus, a Gram-positive model strain, was evaluated. FT-IR results suggested an electrostatic interaction between VM and CH/TPP particles. Moreover, the particles were found to hold a positive zeta-potential, indicating the presence of CH on the particle surfaces. Particle size and encapsulation efficiency were mainly influenced by the different manufacturing processes employed. Nanoparticles obtained by spray-drying showed the best results in terms of water uptake and drug release rate. Moreover, they showed a good bactericidal activity against S. aureus.     

Lineage-related and particle size-dependent cytotoxicity of chitosan nanoparticles on mouse bone marrow-derived hematopoietic stem and progenitor cells

Chitosan nanoparticles (CSNPs) have potential applications in stem cell research. In this study, ex vivo cytotoxicity of CSNPs on mouse bone marrow-derived (MBMCs) hematopoietic stem and progenitor cells (HSPCs) was determined. MBMCs were exposed to CSNPs of different particle sizes at various concentrations for up to 72 h. Cytotoxicity effect of CSNPs on MBMCs was determined using MTT, Live/Dead Viability/Cytotoxicity assays and flow cytometry analysis of surface antigens on HSCs (Sca-1⁺), myeloid-committed progenitors (CD11b⁺, Gr-1⁺), and lymphoid-committed progenitors (CD45⁺, CD3e⁺). At 24 h incubation, MBMCs' viability was not affected by CSNPs. At 48 and 72 h, significant reduction was detected at higher CSNPs concentrations. Small CSNPs (200 nm) significantly reduced MBMCs' viability while medium-sized particle (∼400 nm) selectively promoted MBMCs growth. Surface antigen assessment demonstrated lineage-dependent effect. Significant decrease in Sca-1⁺ cells percentage was observed for medium-sized particle at the lowest CSNPs concentration. Meanwhile, reduction of CD11b⁺ and Gr-1⁺ cells percentage was detected at high and intermediate concentrations of medium-sized and large CSNPs. Percentage of CD45⁺ and CD3e⁺ cells along with ROS levels were not significantly affected by CSNPs. In conclusion, medium-sized and large CSNPs were relatively non-toxic at lower concentrations. However, further investigations are necessary for therapeutic applications.