Effect of Adding Chitosan Nanoparticles to Acrylic Resin on Mechanical and Antimicrobial Properties of Removable Dentures: Scoping Review

Functional enhancement of biopolymer was attempted in this work for food packaging application. Incorporation of chitosan (0–9%) and silica (0–10%) nanoparticles (NP's) into gelatin film (Gel) has been tried and their effects on moisture content, tensile strength (TS), elongation at break (%E), wettability, water vapor permeability (WVP), and antimicrobial activities were studied. Morphology of nanoparticles was studied using scanning electron microscopy and transmission electron microscopy. Chitosan NP's showed agglomeration at higher concentration which leads to lower the mechanical as well as barrier properties of the film. However, silica NP's enhanced the properties of bionanocomposite film. TS was increased from 6.05 MPa of pure gelatin film to a maximum value of 38.91 MPa at CS NP's of 5.8% and Si NP's of 7%; however, %E decreased with addition of nanoparticles resulting in brittleness of film. WVP for pure gelatin film was 25.21 g mm/kPa m2 day, which reduced to 3.30 g mm/kPa m2 day after incorporation of 10% Si NP's. Antimicrobial activity was observed against E. coli and S. aureus. Incorporation of CS NP's improved the antimicrobial activity of gelatin film. Si NP's showed improvement in mechanical and barrier properties of Gel–CS films, however, had no effect on antimicrobial activities.Practical ApplicationResearchers community are more concerned of natural biopolymers to reduce the use of synthetic polymers, especially in food packaging. Gelatin is one of the natural biopolymer and have potential to be used as food packaging material. Problem with gelatin and many other biopolymer based film is their poor mechanical and barrier properties. Present study was framed to overcome these problems by incorporating silica and chitosan nanoparticles in gelatin film. The results observed would be useful to develop a biopolymer based nanocomposite film with improved mechanical, barrier and antimicrobial properties, which can be used for active food packaging.

Back Ground Chitosan as a natural polymer has been fabulated into a number of formulations such as films, hydrogels and particles based on its excellent properties such as biodegradable, biocompotable, bioadhesive, permeartion-enhancement, antibiotic, antitumor etc. properties. Among them, chitosan microparticles found a lot of applications in pharmaceutics such as vaccine delivery, mucosal delivery and gene delivery, etc. Down to the nanoscale, chitosan nanoparticles have more attractive properties more than that of chitosan microparticles, which further widen the applications of chitosan particles in biomedicine and biopharmaceutics. Objective of this Thesis This thesis is aimed to prepare chitosan micro or nanoparticles to delivery proteins. What are the questions this thesis attempted to solve? 1) What are the proper preparation conditions of chitosan micro or nanoparticles? 2) How does the pH value affect the formation and protein encapsulation of chitosan nanoparticles? 3) How to overcome the burst release of chitosan nanoparticles? 4) How to overcome the aggregation disadvantage in the contritional preparation process of TPP-gelated chitosan microparticles? 5) How to construct a composite particles system to realize the sustainable release of proteins? What are the methods used in this thesis? 1) ionotropic gelation method to prepare chitosan nanoparticles 2) Emulsification-coacervation (NaOH) method to prepare chitosan microparticles 3) a polyelectrolytes coacervation method to prepare chitosan-BSA complexes 4) a microemulsion involved emulsification-coalescence method to prepare TPP-gelated chitosan microparticles 5) a nanoparticles encapsulation method to prepare composite particles. Results and Conclutions 1) the effect of preparation parameters on the properties of chitosan nanoparticles: 1a) the concentration of chitosan has no siganificant effect on particles yield, positively associated with particles size, size distribution, positively associated with BSA encapsulation efficiency in a specific concentration range; 1b) the mass matio of chitosan to TPP negatively associated with particles yield, positively associated with particle size and size distribution, negatively associated with BSA encapsulation efficiency; 1c) the concentration of BSA has no significant effect on particles yield, particle size or size distribution, negatively associated with BSA encapsulation efficiency in a specific concentration range. 2) a chitosan polymer chain conformation related mechanism is proposed through the study of the effect of pH value on the formation and BSA encapsulation of chitosan nanoparticles. 3) the most homogeneous and smooth chitosan particles could be obtained at the parameters of: 2% (m/v) chitosan solution, 2/10 w/o volume ratio, 4% Span 85 as susfactant, 5 Krpm homogenization speed and 3 times addition of NaOH solution as a coacervation agent. The obtained particles have a mean diameter of 9.4±1.9 m. The BSA loading test found that dispersed particles only could be obtained below the BSA concentration of 0.5% under above mentioned parameters. 4) a noval polyelectrolytes complex formed by TPP and BSA is obtained attempted to solve the burst release effect of chitosan nanoparticles. 5) a microemulsion involved emulsification-coalescence method is used to overcome the aggregation problem of TPP-gelated chitosan microparticles. 6) a chitosan nanoparticles encapsulated PLA composite particles are successfully constructed. What is new in this thesis? 1) to study the formation mechanism and protein encapsulation of chitosan nanoparticles through the study of the effect of pH value on their properties and propose the role of chitosan polymer chain conformation during this process, 2) a noval TPP-BSA polyelectrolytes complex is obtained base on the purpose to overcome the burst release effect of chitosan nanoparticles, 3) apply emulsification-coalescence method in which a microemulsion of cross-linking agent-TPP is used to solve the aggregation problem of TPP-gelated chitosan microparticles, 4) propose a chitosan nanoparticles encapsulated PLA composite particles to control the release of proteins. Where is the study of this thesis in the field? 1) Chitosan nanoparticles have been extensively investigated in the past few years and the factors which can affect the properties of chitosan nanoparticles have been well documented as well. This thesis provides the evidence from a new side to understand the formation and protein encapsulation mechanisms of chitosan nanoparticles. 2) New and highly effective methods have been proposed by others to prepare protein loaded chitosan microparticles such as sieving and microfluidic methods which can reproduceably scale up the production of monodispersed chitosan microparticles. This thesis just solved a technique problem in the conventional preparation process of TPP-gelated chitosan microparticles. 3) The proposed TPP-BSA polyelectrolytes complex could be an alternative route to overcome the burst release effect of chitosan nanoparticles. 4) The proposed chitosan nanoparticles encapsulated PLA composite particles is one of the solutions among other composite particles proposed by others

Anchorage of the femoral head prosthesis to the shaft of the femur.

Polymethyl methacrylate (PMMA) is widely used as a denture base material despite its limitations, which include low transverse strength, impact resistance, surface hardness, and relatively high-water solubility and sorption. To enhance its mechanical and physical properties, PMMA has been modified by incorporating various metal powder fillers, such as aluminum and copper - despite their tendency to cause discoloration. These modifications aim to improve the overall quality and durability of dental prostheses. To evaluate the influence of incorporating microform propolis powder (known for its antifungal and antimicrobial properties and its rich composition of functional groups) into acrylic denture base material, and to assess its effect on selected physical and mechanical properties of the material. A total of 128 specimens were prepared to evaluate various mechanical properties. Four groups were tested: 1 control group containing acrylic resin without propolis, and 3 experimental groups with propolis powder added at concentrations of 1.0%, 2.0% and 3.0% by weight. Each group consisted of 8 specimens for each mechanical test. All specimens were cured using the conventional heat-curing method. The mechanical properties evaluated included transverse strength, impact strength, surface hardness, and surface roughness. The data were statistically analyzed using the IBM SPSS software. The group with 1.0% propolis addition showed the highest mean values in all tested mechanical properties: transverse strength (90.50 N/mm²), impact strength (10.45 kJ/m²) and surface hardness (84.39). These values were significantly higher than those of the control group, with statistical analysis revealing highly significant differences between groups (p < 0.05) using ANOVA. Regarding surface roughness, the 1.0% propolis group also recorded the lowest mean value (1.03 μm), compared to the control group (2.14 μm), with all experimental groups showing significantly reduced roughness. The incorporation of 1.0% microform propolis powder into PMMA denture base material significantly improved its mechanical and surface properties. These promising results suggest that further studies are warranted - either to explore additional properties or to test different propolis concentrations, potentially combined with coupling agents such as silane to enhance bonding and performance.

Improvements of physical, mechanical and biodegradation properties of polybutadiene rubber insulators by chitosan and silica nanoparticles

Effect of silicon dioxide nanoparticles on the flexural strength of heat-polymerized acrylic denture base material: A systematic review and meta-analysis

Improvement of the antibacterial properties of acrylic resins, used in the construction of removable orthodontic appliances, is an important strategy to reduce the incidence of caries and oral diseases in orthodontic treatments. The addition of antimicrobial agents to acrylic resins is one of the effective methods to enhance the antimicrobial properties of these materials. However, one main concern is that modification of acrylic resin has negative effects on its mechanical properties. Recently, chitosan nanoparticles (NPs), as biocompatible and biodegradable polysaccharides with remarkable antimicrobial properties, have been used in different areas of dentistry and medicine. This study aimed to investigate the effects of adding chitosan NPs on the mechanical properties of a cold-cure orthodontic acrylic resin. The chitosan NPs were added to the acrylic resin in various weight percentages: 0% (control), 0.5%, 1%, 2%, and 4%. The flexural strength, compressive strength, Vickers microhardness, and impact strength measurements were performed for all five groups. The results showed that adding up to 1% (w/w) chitosan NPs to an acrylic resin had no significant negative effects on its flexural strength and compressive strength, while it decreased these parameters at weight percentages of 2% and 4% (w/w). The results also revealed that modification of acrylic resin with chitosan NPs up to 4% had no significant negative effects on the microhardness and impact strength of acrylic resin. In conclusion, the addition of chitosan NPs up to 1% (w/w) had no significant negative effects on the mechanical properties of cold-cure acrylic resin.

Preparation and characterization of hydroxypropyl methylcellulose/hydroxypropyl starch composite films reinforced by chitosan nanoparticles of different sizes

Chia (Salvia hispanica L.) flour seeds produce films with good barrier properties against water vapor and could be used as food packaging; however, their mechanical properties are poor, which limits their application. The incorporation of nanoparticles into natural polymers is a strategy used to improve the properties of films to increase their applications. Furthermore, nanoparticles can encapsulate antioxidant agents and generate active films. The objective of this study was to evaluate the influence of chia flour (4%–7%), glycerol (15%–25%), and chia extract-loaded chitosan nanoparticles (ChCNp) (0%–0.75%) on the physical, mechanical, barrier, structural and antioxidant properties of chia flour nanocomposite films. Chitosan nanoparticles loaded with antioxidant chia extract were synthesized by ionic gelation and incorporated into the films. The thickness, water vapor permeability, tensile strength, and antioxidant properties of the films were evaluated using a Box-Behnken experimental design. Structural analysis was conducted using the FTIR technique. The results of the ANOVA of the responses were adjusted to second and third order polynomial models obtaining determination coefficients of 0.96–0.99. The water vapor permeability of the films was 3.89 × 10-8–1.68 × 10−7 g mm/Pa s m2, tensile strength was 0.67–3.59 MPa and antioxidant activity was 57.12%–67.84%. The variables presented different effects on the films. Increasing the chia seed flour concentration negatively affected the water vapor permeability but improved the tensile strength and the antioxidant capacity of the films. The increase in glycerol concentration caused the films to become brittle. The nanoparticles had a significant effect on the thickness of the films and improved their mechanical and antioxidant properties. However, they did not show an effect on barrier properties. The results demonstrate that it is possible to obtain nanocomposite films with antioxidant capacity from chia seed flour and with the incorporation of chitosan nanoparticles loaded with antioxidants.

The aim of this study was to formulate and systematically evaluate in vitro and in vivo Helicobacter pylori (Hp) efficacy of chitosan (CS) nanoparticles (NPs). CS NPs were prepared by the polymerid dispersion method. The in vitro anti-Hp effect of concentration, pH and deacetylation degree of CS NP solutions was detected. Then, 60 BALB/c mice were randomly divided into 3 groups and Hp-infected mice were established by inoculating with Hp strain. Thereafter that, mice in different groups received PBS, CS solution of CS NP solution intragastrically, twice daily for 14 consecutive days. Four weeks after the last administration, the mice were killed and part of the gastric mucosa was embedded in paraffin, cut into sections and assayed with Giemsa staining. Part of the gastric mucosa was used to quantitatively culture Hp. At pH 4–6, the anti-Hp effect of CS NP solution had a negative correlation with pH value (P < 0.01), and the optimal pH value was 4; there was a significant difference in anti-Hp effect between 88.5% deacelytation degree (DD88.5) CS NP and 95% deacelytation degree (DD95) CS NP (P < 0.05–0.01). The anti-Hp effect ranked from high to low, i.e., from DD95 CS NP to DD88.5 CS NP; the anti-Hp effect of DD88.5 CS NP and DD95 CS NP showed no difference within between 5 and 20 g/l (P > 0.05). The Hp eradication rate was 0, 55 and 75%, respectively, among the three groups (P < 0.01) and the Hp colonized density in the control group and CS group was significantly higher than that in the CS NP group (P < 0.01, 0.05). These results suggest that CS NP improves the anti-Hp efficacy of CS in vitro or in vivo and has the potential to kill Hp directly.

A quitosana é um biopolímero com ampla aplicação na área cosmética, têxtil, alimentícia e na agricultura. Neste trabalho nanopartículas de quitosana (NPQ) foram sintetizadas por gelificação iônica e foram utilizadas no recobrimento de laminados a base de blenda de amido e poli(ácido lático) (TPS/PLA) produzidas por extrusão termoplástica. Nas NPQ determinou-se o diâmetro médio, a morfologia por microscopia eletrônica de transmissão e a atividade antimicrobiana frente aos microrganismos Salmonella typhimurium, Staphylococcus aureus, Penicillium expansum e Aspergillus ochraceus. Nos laminados de TPS/PLA recobertos com NPQ foram determinadas as propriedades mecânicas e a permeabilidade ao vapor de água. As NPQ foram produzidas com êxito através do método de gelificação iônica, o diâmetro médio foi de 146,9 nm, o índice de polidisperção foi de 0,281 e apresentaram morfologia esférica. As NPQ não apresentaram atividade antimicrobiana frente aos microrganismos estudados. Entretanto, sua aplicação como recobrimento em laminados extrusados de TPS/PLA não alteraram as propriedades mecânicas e de barreira ao vapor de água e a espessura.

Ni-Mo coatings exhibit desirable corrosion and mechanical properties. Further improvements in their properties can significantly enhance their industrial applications. Reinforcing agents can be incorporated to address this priority. In the present investigation, Ni-Mo alloy and Ni-Mo-Y2O3 nanocomposite coatings were electrodeposited on the copper substrates to study the influences of Y2O3 nanoparticle content on the morphological, microstructural, mechanical, and corrosion properties of the coatings. Results exhibit that there is no change in the phase structure of the Ni-Mo alloy coatings with the incorporation of nanoparticles. Albeit the fact that introduction of the nanoparticles has no influence on the surface morphology of the coatings and all of the electrodeposited coatings show featureless morphology, there is a recognizable decrement in the number of surface-related defects such as pores, voids, and microcracks. Generally, mechanical and corrosion properties of the alloy coatings improve with nanoparticle embedment. Ni-Mo coating electrodeposited from a bath containing 3 g/L Y2O3 (Ni-Mo-3g/L Y2O3) shows the highest microhardness and corrosion resistance primarily originated from its higher Y2O3 content.

Background: Poly methyl methacrylate (PMMA) is widely used in dentistry as a denture base material. But the material has some inherent drawbacks in its mechanical properties like impact strength and flexural strength which can lead to fracture of the prosthesis. So the present study was conducted to evaluate and compare both impact and tensile strength in conventional acrylic resin and veined acrylic resin reinforced with one weight percentage titanium dioxide nanoparticles. Objectives: 1. To determine and compare the effect of incorporation of titanium dioxide nanoparticles on tensile strength in megapascals between heat activated and veined acrylic denture base resins. 2. To determine and compare the effect of incorporation of titanium dioxide nanoparticles on impact strength in kilo joules per meter square between heat activated and veined acrylic denture base resins. Materials and Methods: 80 specimens were prepared and grouped into Eight groups (A1, A2, B1, B2, C1, C2, D1, and D2) with10 specimens in each. Group A1, A2, B1 and B2 was used to study tensile strength and Group C1, C2, D1 and D2 was used to study impact strength. Group A1 and C1 were conventional heat cure acrylic, group A2 and C2 were the modified ones with one weight percentage (1wt%) titanium dioxide nanoparticles, groups B1 and D1 were veined acrylic, group B2 and D2 were the modified veined acrylic with 1wt% titanium dioxide nanoparticles. Tensile strength was tested using INSTRON universal testing machine and impact strength was tested using IZOD impact tester. Results were analyzed using independent t-test followed by Bonferroni’s correction to control the p value. Results: Mean and standard deviation of tensile strength of group A1 was 53.2110.36 Mpa, group A2 was 56.873.96 Mpa, group B1 was 44.483.31Mpa and group B2 was 53.164.62 Mpa. The mean and standard deviation of impact strength of group C1 was 8.720.78 Kj/m2, group C2 was 10.100.40 Kj/m2, group D1 was 9.230.34 Kj/

SUMMARYResearch backgroundAmaranth (Amaranthus hypochondriacus) flour produces films with excellent barrier properties against water vapor, allowing food preservation, but the mechanical properties are poor compared to synthetic films. One strategy to improve these properties is the incorporation of nanoparticles. The particles can also serve as a vehicle for the addition of antioxidant agents into the films. The objective of this work is to optimize the formulation for the preparation of amaranth flour films treated with antioxidant chia (Salvia hispanica L.) extract-loaded chitosan particles using response surface methodology (RSM).Experimental approachChitosan nanoparticles with the extract were synthesized by ionic gelation, and the films were made by the casting method. Three independent variables were assigned: amaranth flour (4-6%), glycerol (25-35%) and chitosan nanoparticles loaded with the chia extract (0-0.75%). We then evaluated the physical (thickness), mechanical (tensile strength, Young´s modulus and elongation), barrier (water vapor permeability, moisture and water solubility) and antioxidant properties of the films. The experimental results of the properties were analyzed using a Box-Behnken experimental design generating 15 runs with three replicates at the central point.Results and conclusionsSecond and third order polynomial models were obtained from the ANOVA analysis of the evaluated responses, and high coefficients of determination were found (0.91–1.0). The water vapor permeability of the films was 0.82−2.39·10-7 (g·mm)/(Pa·s·m2), tensile strength was 0.33−1.63 MPa and antioxidant activity 2.24−5.65%. The variables had different effects on the films: glycerol negatively affected their properties, and the permeability values increased with increased amaranth flour content. The nanoparticles improved the mechanical, barrier and antioxidant properties of the films compared to the films without nanosystems. The optimal formulation was 4% amaranth flour, 25% glycerol and 0.36% chitosan nanoparticles. The optimized films had better mechanical (1.62 MPa) properties, a low water vapor permeability value (0.91·10-7 (g·mm)/(Pa·s·m2)) and moderate antioxidant activity (6.43%).Novelty and scientific contributionThe results show the effect of chitosan nanoparticles on the properties of amaranth flour films for the first time. The resulting equations are useful in the design of food packaging.

Biodegradable composite films have been prepared from corn starch (CS) incorporating chitosan (CH) and nanoTiO2 by a solution casting method and the mechanical, physicochemical and antimicrobial properties of the films were determined. Scanning electron microscopy (SEM) observations demonstrated that the appropriate proportion of components resulted in ideally homogeneous surface of films. Fourier transform infrared (FTIR) spectra analysis revealed that hydrogen bonds were formed between CH and CS and a covalent interaction existed between the nanoTiO2 and the CS and CH. The addition of proper amounts of CH to a CS matrix produced an enhancement of mechanical and antimicrobial properties accompanied by lower water moisture resistance. Incorporation of nanoTiO2 into the CS/CH film increased the tensile strength, moisture resistance and impermeability to oil and achieved significant antimicrobial properties. The tensile strength of the nanoTiO2/CH/CS composition film was 21.12 ± 0.34 MPa which was 6.27 times that of a plasticized CS film, while the antibacterial activity for Escherichia coli reached 94 ± 2%. The mechanical properties, moisture resistance and antimicrobial properties of the films were deteriorated by the incorporation of excessive nanoTiO2 because of self-aggregation of the nanoparticles.