هادی تابش

Among 3 to 30 percent of women of reproductive age, experience abnormal uterine bleeding (AUB). Vaginal rings are one of the systems of interest for the local delivery of hormones that due to their polymeric structure allow prolonged release of drug. In this study, the design and fabrication of matrix vaginal rings containing levonorgestrel (LNG) were investigated.

In this experimental study, at first, two pieces of aluminum mold were designed, then base (A) and cross-linker parts (B) of polymer with LNG were mixed and 48 polymeric rings containing LNG were manufactured by injection molding method. To achieve the desired drug release values in a given time, the effect of temperature, rpm, release environment, different initial loading, cross-linker percentage and a mathematical model to predict release and swelling test were investigated.

 As a result of the experiments, it was revealed that with increasing drug loading, the release rate rises, while increasing the cross-linker percentage reduced the drug release. Finally, the ring A:B=100:9.5 with an initial loading of 0.2 % LNG relative to silicon was selected as an appropriate ring, and release experiments were performed at 37 °C, shaker speed of 80 rpm, and release medium containing 10 % ethanol. Drug release values were measured by spectrophotometer and analyzed by SPSS statistical software version 16.

Based on the results, it can be deduced that matrix vaginal ring containing LNG is a suitable drug delivery system for prolonged release of LNG for treatment of AUB that depending on the drug initial loading and cross-linker percentage, the required diffusion coefficient, and release rate can be achieved in a certain time.

Zeolites are high-porous active crystalline biomaterials. Recently many studies have been done on their antibacterial properties especially on zeolites exchanged with metallic cations. In this paper, we investigate the effective factors on the antimicrobial activity of natural and synthetic zeolites exchanged with silver, zinc, copper nickel, and bromide cations. This study reviews the published articles on the antibacterial properties of the natural and synthetic pure zeolites as well as the ion exchange ones. The results of our investigation show that ion exchange zeolites exhibit a very good antibacterial effects even in comparison with other conventional antibacterial materials. The strongest antibacterial activity was reported in silver exchanged zeolites against Bacillus cereus and Escherichia coli with MIC of 16 μg/ml. According to the results reported derived from different articles, it can be concluded that zeolites with biocompatibility and high ion exchange capacity can be used as efficient antibacterial materials. Pure zeolites have antibacterial activity at high concentrations, whereas all synthetic and natural zeolites exchanged with metal cations investigated in this paper exhibit good antibacterial activity at very low concentrations generally due to sustained and prolong release of metal cations.

The use of bone scaffolds is one of the new and efficient techniques for repairing bone defects that provide a suitable platform for cell proliferation and growth to repair the target tissue. One of the most important causes of failure of transplants and surgical procedures is the invasion of bacteria at the site of the complication and the development of severe infection. The purpose of this study, which was carried out at the Faculty of New Sciences and Technologies, University of Tehran at 2017-2019, Antibacterial Properties of Porous Scaffolds Made of Gelatin, Calcium Phosphate Zeolite with Loading of Clindamycin.

In this study, freeze-drying was made from a combination of gelatin, calcium phosphate, and natural zeolite of bone tissue scaffolds and then the drug was loaded with different amounts of clindamycin. The surface of the scaffold was examined by scanning electron microscopy and antibacterial test and drug release test were performed on the scaffold.

The results showed that the aforementioned composite scaffold did not induce growth inhibition in the antibacterial test, However, after loading the drug on the scaffold with a concentration of 0.01 drug, the growth zone was 2 and 4 mm in diameter for Escherichia coli and Staphylococcus aureus, respectively.

Addition of the antibacterial agent clindamycin to the bone scaffold made a suitable substrate for drug delivery to bone tissue at the site of removal has been removed to prevent the growth of infection at the scaffold implant during the first period of repair.

Due to the composite structure of the jaw bone, gelatin and beta-calcium phosphate (b-TCP) biomaterials have been used repeatedly in bone tissue engineering. Despite the desirable properties of scaffolds made, their application has been limited due to their poor mechanical properties and high degradability. The aim of this study was to investigate the effect of clinoptilolite biomaterial with unique mechanical properties such as remarkable mechanical properties, low degradation rate and highly favorable biocompatibility properties in gelatin and b-TCP scaffolds.

Preparation of porous scaffold as a template was made leading to freeze drying method using weight percent of 50 for gelatin, 25 b-TCP and 25 Clinoptilolite. SEM analysis and image j software was used in order to evaluation of scaffold surface and finding of porosity frequency. Finally, compressive strength of scaffold was evaluated. 

In clinoptilolite / b-TCP / Gelatin scaffolds, porosity up to 250 nanometers was recorded which was the best for angiogenesis. In addition to gelatin, clinoptilolite also had a positive effect on porosity. Using compressive strength analysis, increasing of Youngchr('39')s modulus was also observed from 100 to 166 mega Pascal by that Clinoptilolite is the most effective agent in modifying this modulus.

Considering the results, clinoptilolite that in addition to improving and enhancing the mechanical properties of composite scaffolds, had a significant effect on the increase in the size and porosity of jaw bone tissue engineering scaffolds. According to the obtained characteristics it can be said that the sample presented is in accordance with the properties of extracellular scaffold (ECM) of jaw bone tissue and would be a suitable choice in tissue engineering of this type of bone.

More than one-third of women experience abnormal uterine bleeding (AUB) during their lifetime. One of the treatment methods of this disease is hormone therapy. Vaginal rings (VRs) containing progesterone hormones could be a good choice for treatment. In this study, the design and construction of a reservoir ring with the ability to release levonorgestrel hormone has been investigated.

In this experimental study, to make vaginal rings containing levonorgestrel, biocompatible silicone fibers were used, the two ends of which were connected with special caps. Different amounts of LNG including 0.1, 0.2 and 0.4 weight percent relative to paraffin were loaded into the fibers. These three prototypes were named RSC1, RSC2, and RSC3, respectively. The daily and cumulative release of LNG from these rings was measured by spectrophotometer and compared using SPSS software version 16 and analyzed by one-way ANOVA method.

On the first day, there was a burst release that was different for these three prototypes depending on the drug loading percentage. From the second until thirtieth day for RSC3 and from forth until thirtieth day for RSC1 and RSC2, prolonged release was achieved and average daily release for RSC1, RSC2, and RSC3 were 24.10 ± 8.22, 41.77 ± 9.02 and 83.29 ± 5.07µg, respectively.

According to the findings, it is possible to design VRs capable of prolonged and sustained release of LNG for up to 30 days and control their daily release rate based on initial drug loading. This method may be a suitable alternative to oral hormonal pills in the treatment of AUB.

Zeolite is an active biomaterial which has also biocompatible, antibacterial non-toxic and high porosity properties. In recent years many investigations have been performed on its application in different fields of sciences. In this study, a systemic review on zeolite application in advanced medical sciences and introduction of potential zeolite types for such uses. Investigating the literatures, zeolite’s applications in medicine were classified in different fields e.g. pharmaceutics, orthopedics, tissue engineering, and dentistry. It was also clarifies that the proper selection of a zeolite type is crucial for any specific research activity since they demonstrate diverse physico-chemical properties. Zeolites are edible, antibacterial, biocompatible and non-toxic material with high absorption property, whose application in different medical fields are expanding. Choosing zeolite, either synthetic or natural, can be a proper selection for e.g. drug delivery systems, wound healing, scaffolds in tissue engineering, implant coatings, hemodialysis, gas adsorption and elimination of toxic ions. In order to bring all these application under an umbrella, two classifications based on application types biological and physico-chemical properties of zeolites have been presented which provides an overview on medical applications of zeolites and also helps scientists in better selection of zeolite type for their research activities.

Several therapeutic methods need an artificial lung (oxygenator) to replace the natural lung function. For instance in some acute respiratory syndromes, the patient’s lungs are unable to perform their normal function and would need an assistive device to fulfill their performance. Moreover, in open heart surgery, when the heart has stopped pumping, blood is not sent to the lungs, and should be flowed in an extracorporeal circuit. The demand to design a proper oxygenator had begun since more than three centuries ago, and has achieved significant achievements so far. Efforts have been made to promote the performance characteristics of oxygenators by increasing their hemocompatibility, providing larger surface area between blood and gas phases, reducing blood pressure drop between inlet and outlet flow and lowering their priming volume. This article reviews the history, structural and functional properties of oxygenators and provides a wide perspective of their clinical applications for adults, children and neonates. Moreover, techniques used in each prototype, as well as limiting factors are discussed. The state of art oxygenators and future aspects towards implantable oxygenators are also introduced which might be effective in motivating biomedical scientists to conduct their researches in this field.

Hollow fiber membrane contactors have been applied in various industries e. g. chemistry، petroleum، biotechnology and medicine. They are also widely used in artificial organs e. g. artificial lung، kidney and liver as well as some pharmaceutical procedures such as separation and purification of biological materials. Intrinsic properties of hollow fiber membranes، such as high packing density and high mass transfer rate have increased the use of these membranes. In tissue engineering، using such membranes is of great importance for membrane bioreactors and culturing of cells sensitive to stress and those which require high mass transfer rates. This article comprehensively investigates the use of the hollow fiber membrane contactors applied in advanced medical sciences and pharmaceutics. Their composition materials in addition to the important factors affecting their performance characteristics are also discussed.