جستجوی مقالات مرتبط با کلیدواژه « nano » در نشریات گروه « پزشکی »

In this study, nanosilica modified with HS-SiO2 thiol groups was utilized as adsorbent for solid phase extraction, as a fast and reliable method of preconcentration and separation of very small quantities of selenium ions from water and blood samples.
            

The samples included four natural water samples and one biological sample (blood serum) prepared in volumes of 25, 100, 200, 300, 400 and 500 ml. The samples were analyzed by solid phase microextraction, using thiolated-nanosilica (as adsorbent), ultraviolet-visible spectrophotometry and atomic absorption spectroscopy.
            

Optimized conditions for preconcentration of a 25 ml 0.2 mg/l selenium solution were pH 5, 40 mg of adsorbent, sample-adsorbent mixing time of 15 minutes and 5 ml of 2N sulfuric acid as detergent. The volume limit and concentration factor were 400 and 80, respectively. Limit of detection and relative standard deviation of the method were 0.46 μg/l and 0.9%, respectively.
            

This study is the first to successfully utilize thiolated nanosilica for measuring low selenium levels. Thiolation of the absorbent increases selenium adsorption by thiolated-silica compared to SiO2.
       

Natural nano-sized Clinoptilolite (NCLN) as a conventional treatment for Type 2 diabetes mellitus may reduce glucose concentration and improve levels of minerals and lipid profile (LP).

The aim of this study was to compare the effects of NCLN with Metformin (Met) on fasting blood glucose (FBG), LP, levels of the several minerals, and body weight (BW) in rats with high-fat-diet (HFD)/Streptozotocin (STZ)-induced diabetes.

In this experimental study, 33 male Wistar rats were divide into four groups of A) healthy (n = 6), B) diabetic: (1) NCLN (n = 9) 2% of food, (2) diabetic receiving Met (n = 9) 100 mg/kg BW/day and (3) diabetic control (DC) (n = 9). The diabetic subgroups were fed with an HFD for one month and injected with a single dose of intra-peritoneal STZ (35 mg/kg BW). At the end of the 7th week, FBG, insulin, homeostatic model assessment of insulin resistance (HOMA-IR), LP, and serum levels of some minerals were evaluated.

There were no significant differences in FBS, total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-c) among the groups, however, high-density lipoprotein cholesterol (HDL-c) level was significantly higher in the DM (32.92 ± 1.14) and NCLN (32.63 ± 0.73) groups in comparison with the DC group (31.64 ± 0.78) (P = 0.01). The mean score of Cu level in the DM group was significantly different from that in the DC group (2.15 ± 0.48 vs. 1.54 ± 0.21; P = 0.03). Moreover, Met significantly increased serum level of Ca as compared to the DC group (86.65 ± 10.03; P = 0.01). Also, treatment with Met favorably prevented severe weight loss until the last week of treatment.

Natural nano-sized Clinoptilolite and/or Met did not significantly affect levels of serum glucose, minerals, and lipid profile, but a significant increase in HDL-c was observed as a result of NCLN and Metformin treatment, and Cu and Ca levels increased only in the Metformin group

Backgound: The aims of this study were to evaluate the antimicrobial properties and synergistic effects of nano-titanium dioxide (TiO2), nano- zinc oxide (ZnO) and two synthetic peptides (mastoparan-B, indolicidin) against drug-resistant strains of Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii.
From March to August 2015, a total of 30 (10 each) isolates of the above bacteria were recovered from patients in the ICU of two referral hospitals in Kerman, Iran. The sizes and purities of nano-TiO2, nano-ZnO were determined by scanning electron microscope (SEM) and X-ray diffraction (XRD). Similarly, mass spectroscopy and HPLC were used for checking the genunity of the peptides. Antibiotic sensitivity was determined by agar disk diffusion assay. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) activities of nanometals and synthetic peptides were assessed by CLSI broth microdilution test. Similarly, checkerboard and time-kill curve analysis were performed to determine the synergistic activities of these compounds.
Mastoparan-B had potent toxicity to all isolates with an average MIC 4 ± 0.2 mg/L, while TiO2-NP had lowest antimicrobial activity with MIC range 1280 ≥ ± 0.2 mg/L (P. aeruginosa growth was not inhibited by TiO2 and ZnO NPs). The bactericidal activity against the isolates in descending order was mastoparan-B, indolicidin, nano ZnO, and nano TiO2, respectively. Further investigation on synergism using fractional inhibitory concentration index (FIC) revealed that, nano-TiO2 and nano-ZnO combination had an additive effect (FIC = 0.95 ± 0.1) on A. baumannii and K. pneumoniae strains, whereas, P. aeruginosa isolates were indifferent to this combination (FIC ≥ 2 ± 0.2). In contrast, mastoparan-B and indolicidin combination displayed broad synergistic effect (FIC = 0.5 ± 0.1) on all the isolates and caused rapid killing of the organisms within 4 h of incubation.
Our results showed that the combination of mastoparan-B and indolicidin peptides is a suitable candidate for substitution of the antibiotics for topical treatment of infections caused by drug- resistant bacteria. to determine the incidence and prevalence of Shiga Toxin producing E. coli (STEC), as a cause of urinary tract infection in Iran.

Bone defects have caused many problems. Restoration of bone defects with great gaps, has been a huge problem for many patients. Nowadays, different ways are used for bone restorations that cause difficulties; so there is tendency to use organic drugs such as propolis. The aim of this study was investigating the effects of nono-honey on calvarial defect. In this research 20 Wistar male rats were divided into two control and nano-honey groups. After general anesthesia, to access the calvaria, the midline was cut. We turned the skin and periosteum over and dig a fossa in parietal bone with electronic handpiece with 1000 round per minute (depth 5 mm and length 6 mm). After 8 weeks, histopathologic samples were provided and the new vessels, neutrophils, lymphocytes, macrophage, fibroblast, granulation tissue and formation of fresh bone trabeculae were measured. We observed that average number of neutrophils in nano-honey group was lower than control group, expressively (p = 0.030). The average of bone trabuculation in nano-honey group was more than other group (p 0.05). In this study, it was shown nano-honey has positive effects on restoration of hard and soft tissues. Since this research was carried out on rats more study and examinations on human beings are needed. Furthermore, adding osteoconductive and stimulant of regenerating bones in order to evaluate the effects on restoration is recommended.

The antibiotic resistance of bacteria has increased in the last decade. The mecA gene plays an important role in the pathogenicity of Methicillin-Resistant Staphylococcus aureus (MRSA) by increasing antibiotics resistance. Recent studies have indicated that nanotechnology, as an antimicrobial agent, has had promising results.
The present study was conducted to determine the effect of Cu-BPDCA-Ty on antibacterial activity and mecA gene expression in clinical and standard strains of MRSA.
The phenotypic tests were used to identify MRSA strain and confirmed with molecular detection of mecA gene. Synthesized Cu-BPDCA-Ty was confirmed with different techniques such as XRD and SEM analysis. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined by the micro broth dilution method. Real time PCR was used to investigate gene expression. Pta gene was considered as an endogenous control for normalization. Data were analyzed using one sample t test and paired t test in the SPSS software Version 22.
The findings indicated that the MIC and the MBC of Cu-BPDCA-Ty against the standard and clinical strains of MRSA were 0.5 mg/mL, 0.8 mg/mL, 0.46 ± 0.08 mg/mL, and 0.7 ± 0.1 mg/mL, respectively. Analysis of the real- time PCR indicated that all treated groups with Cu-BPDCA- Ty showed a significant decrease in the expression of the mecA gene compared to the control group (P Cu-BPDCA-Ty had an antibacterial effect on MRSA and induced downregulation of expression of the mecA gene.

The main purpose of the current study was to determine the effect of nano-capsules containing risedronate on calvarial bone formation in rabbit.
Fifteen adult rabbits were allocated to the study. Four holes were created in the calvarial bone. Holes 1-4 were filled as described below: hole 1 was right unfilled and kept as control; hole 2 was filled with nano bone; hole 3 was filled using an autogenous bone; and hole 4 was filled with a mixture of nano-capsules containing risedronate. At 4, 8 and 12 weeks after surgery, blood samples were obtained and red blood cell, white blood cell, hemoglobin, hematocrit, mean cell volume, mean cell HGB and platelet counts were determined. Then animals were scarified and bone density was determined using radiography images.
Bone formation in nano risedronate autograft and autograft were 0.31 ± 0.03 and 0.25 ± 0.02, respectively, while in nano risedronate and control groups were 0.11 ± 0.01 and 0.08 ± 0.02, respectively (P 0.05).
These results suggest nano risedronate autograft has positive effects on calvarial bone defects healing in rabbit.

The aim of this in vitro study was to evaluate the cytotoxicity of a new nano zinc-oxide eugenol (NZOE) sealer on human gingival fibroblasts (HGFs) compared with Pulpdent (micro-sized ZOE sealer) and AH-26 (resin-based sealer).
Methods and Materials: The Pulpdent, AH-26, and NZOE sealers were prepared and exposed to cell culture media immediately after setting, and 24 h and one week after setting. Then, the primary cultured HGFs were incubated for 24 h with different dilutions (1:1 to 1:32) of each sealer extract. Cell viability was evaluated by methyl thiazolyl diphenyl tetrazolium bromide (MTT) assay. The results were compared using two-way analysis of variance followed by Tukey’s post hoc test. The level of significance was set at 0.05.
All sealer extracts, up to 32 times dilutions, showed cytotoxicity when exposed to HGF immediately after setting. The extracts obtained 24 h or one week after setting showed lower cytotoxicity than extracts obtained immediately after setting. At all setting times, NZOE showed lower cytotoxicity than Pulpdent and AH-26. While one-week extracts of NZOE had no significant effect on the viability of HGF at dilutions 1:4 to 1:32, both Pulpdent and AH-26 decreased the cell viability at dilutions of 1:4 and 1:8.
NZOE exhibited lower cytotoxicity compared to Pulpdent and AH-26 on HGF and has the potential to be considered as a new root canal filling material.

Poly [2-methacryloyloxyethyl phosphoryl choline (MPC)-co-n-buthyl methacrylate (BMA)-co-p-nitrophenyl-oxycrabonyl poly ethylene glycol-methacrylate (ME- ONP)] (PMBN), a biocompatible terpolymer, is a unique polymer with applications that range from drug delivery systems (DDS) to scaffolds and biomedical devices. In this research, we have prepared a monomer of p-nitrophenyl-oxycarbonyl poly (ethylene glycol) methacrylate (MEONP) to synthesize this polymer. Next, we designed and prepared a smart, water soluble, amphiphilic PMBN polymer composed of MPC, BMA, and MEONP.
In this experimental study, we dissolved MPC (4 mmol, 40% mole fraction), BMA (5 mmol, 50% mole fraction), and MEONP (1 mmol, 10% mole fraction) in 20 ml of dry ethanol in two necked flasks equipped with inlet-outlet gas. The structural characteristics of the synthesized monomer and polymer were determined by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (H-NMR), dynamic light scattering (DLS), gel permeation chromatography (GPC), scanning electron microscope (SEM), and transmission electron microscope (TEM) analyses for the first time. We treated the polymer with two different cell lines to determine its biocompatibility.
FT-IR and H-NMR analyses confirmed the synthesis of the polymer. The size of polymer was approximately 40 nm with a molecular weight (MW) of 52 kDa, which would be excellent for a nano carrier. Microscopic analyses showed that the polymer was rodshaped. This polymer had no toxicity for individual cells.
We report here, for the first time, the full properties of the PMBN polymer. The approximately 40 nm size with an acceptable zeta potential range of -8.47, PDI of 0.1, and rod-shaped structure indicated adequate parameters of a nanopolymer for nano bioapplications. We used this polymer to design a new smart nano carrier to treat leukemia stem cells based on a target DDS as a type of bio-application.

Background. Many types of toothpastes contain substances that can remineralize initial enamel caries. This study aimed to assess the effect of nano-hydroxyapatite (NHA) on microhardness of artificially created carious lesions.
Methods. In this in vitro study, NHA was prepared using sol-gel technique and added to the toothpaste with 7% concentration. A total of 80 extracted sound teeth were collected. The crowns were polished using 500-grit abrasive paper. The specimens were randomly coded from 1 to 80. Number 1 to 40 were assigned to group A and numbers 41 to 80 to group B. The microhardness was measured using HVS-1000 Vickers microhardness tester. The specimens were demineralized using 37% phosphoric acid for 3 minutes in order to create artificial carious lesions and then were rinsed with water, air-sprayed for 3 minutes and dried. Microhardness was measured again. Next, the specimens were brushed for 15 days, twice daily, for 15 seconds. After 15 days, microhardness was measured again. Toothpaste A contained NHA and fluoride and toothpaste B contained fluoride alone. Data were analyzed using SPSS 16, with one-sample Kolmogorov-Smirnov test and ANOVA at a significance level of P Results. The microhardness of specimens significantly decreased following acid exposure (P Conclusion. The toothpaste containing NHA was more effective than the toothpaste without NHA for the purpose of remineralization.

Polyethylene composites including boron can be used as an effective neutron shield. Our investigation focuses on manufacturing borated polyethylene nano-composite. The purpose of this study is to design a radiation shield for use in both neutron and gamma fields.
Borated polyethylene shields containing 2%, and 5% weight percentage of Boron nano-particles were constructed and their neutron attenuation was compared with pure polyethylene. Polycarbonate films were used to find the attenuation of Am-Be neutrons after passing the shields. Mechanical properties of the shields were finally compared.
Mean (± SD) number of α tracks induced by neutrons passing through the shields, were found to be 1.0488×103±128.98, 1.1972×103±289.56and 1.5340×103±206.52 for polyethylene with 5% by weight, polyethylene with 2% by weight boron nano-particles, and pure polyethylene, respectively. The neutron spectrum after each shield was also obtained by MCNP4C Monte Carlo simulations. On the other hand, borated polyethylene nano-composites showed higher tensile strength compared to that of pure polyethylene. Attenuation of neutrons measured in experiments and the result of MCNP simulation were in good agreement.
A statistically significant difference was found between neutron attenuation by borated polyethylene nanocomposite made of 5% by weight boron and pure polyethylene. However, the difference between borated polyethylene nano-composite with 5% weight and 2% wt boron was not statistically significant.

Propose: Bacterial pneumonia is a common lung infection caused by different types of bacteria. Azithromycin (AZI), an azalide antibiotic, is widely used to manage pneumococcal infections. Studies have shown that antibiotics in nanocarriers may lead to increased antibacterial activity and reduced toxicity. The aim of this work was to valuate in vitro antibacterial performance azithromycin-Eudragit RS100 nano-formulations against Streptococcus pneumoniae and Staphylococcus aureus.
AZI-Eudragit RS100 nanoparticles were prepared via electrospinning technique and the in vitro antibacterial performance against S. pneumoniae and S. aureus were assessed using agar dilution method.
Nanofibers in the sizes about 100-300 nm in diameter and micro scale in length and nanobeads in the range of 100-500 nm were achieved. The Minimum Inhibitory Concentrations (MIC) showed an enhancement in the antimicrobial effect of AZI-Eudragit RS100 nanofibers (40 µg/ml) compare to untreated AZI solution (>160 µg/ml) against S. pneumonia. The MIC value for AZI-Eudragit RS100 nanofibers against S. aureus was >128 µg/ml, same as that of the untreated AZI solution.
The enhanced efficiency of AZI in nanofibers could be related to the more adsorption opportunity of nanofibers to S. pneumonia capsulated cell wall which provides an antibiotic depot on the bacterial surface compared to S. aureus. AZI-Eudragit RS100 nanofibers with enhanced antimicrobial effect against S. pneumonia can be considered as a candidate for in vivo evaluations in antibiotic therapy of Pneumococcal infections.

Resin composites are an important part of restorative treatment in modern dentistry. There are many trademarks available in Iran market and physico-chemical properties of many of these resin composites are not evaluated yet. This study was carried out to evaluate the physico-chemical properties of four available resin composites and also to assess the effect of aging on their properties. The findings of this study help clinicians to choose the best materials available.
Four types of resin composites available in Iran market including Filtek Z350 XT, Filtek Z250, Herculite XRV Ultra and Herculite XRV were evaluated. Five samples were made of each composite using a metal mold (2* 10 * 10 mm). Two areas of each sample were light cured for 40 seconds. Samples were kept in saline for 24h and then underwent polishing process. Samples of each group were randomly allocated to five groups held in different conditions as follows: room temperature, distilled water in 37˚C, Distilled water plus hydrochloric acid, distilled water and thermocycling (5000 rounds of 5-55˚C), distilled water, thermocycling, and hydrochloric acid. At the end of one month, indentation was applied on each sample using nano-indentation technology (TriboIndenter, Hysitron, Minneapolis,MN).
The results of this study revealed that the type of composite and the environmental conditions affect elasticity and nano-hardness.
storage conditions affected the elasticity of Filtek Z350XT, Herculite XRV Ultra and Herculite XRV and the hardness of Filtek Z350 XT and Herculite XRV Ultra.

Introdouction: One of the existing problems in the field of dentistry is the use of utilizing materials. Utilizing materials in dentistry must have high rigidity and resistance and a beautiful appearance. The weak formulation of dentistry materials causes irritation, side effects, and increases the cost of healthcare. Therefore, farms and organizations related to dentistry care are trying to produce highly efficient products. Therefore, in the current research, we attempted to recognize and rank the factors that impact on the utilization of nanotechnology in dentistry by an MCDM Fuzzy approach. The statistical community of the present research includes dentists and university experts, who are active in the field of Nano- Dentistry in Mazandaran, Dentist College in Sari . They are selected by the consensus of two groups. The first group included managers and superordinate experts of the organization with 32 people for localizing the modeling. In the second group, five experts as the statistical sample were selected.
The descriptive method and descriptive survey were used. Therefore, by exploring the scientific texts, the criteria were recognized, and their reliability then proved by experts.
By using the screening (decimal-fuzzy), 21 factors were recognized as important and effective in the use of nanotechnology in dentistry. To determine the impact and influence of these factors, the DEMATEL technique was used.
According to the results, decreasing dental plaque had the most impact, and the cost of technology was the most influential factor..