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

Objectives:

 Bone regeneration is one of the most challenging issues in medicine, for which researchers have been seeking new practical strategies. Calcium phosphate cements (CPCs) are proper candidates for bone scaffolds due to their high biocompatibility, self-setting features, and similar mineral content to the bone.

Methods:

 The present study aimed to fabricate composite CPC/ dexamethasone-loaded PLGA microsphere scaffolds, which significantly affected tissue remodeling, and to determine their potential for bone regeneration purposes. The SEM images were used to study the microstructure of the fabricated scaffolds and to investigate the distribution of PLGA in CPC. Moreover, FTIR analysis was performed to determine the chemical components of the fabricated scaffold and to approve the presence of dexamethasone and PLGA in the composite scaffolds. Next, ultraviolet spectroscopy was used to determine the amount of dexamethasone released over time.

Results:

 The FTIR results confirmed the presence of dexamethasone in the scaffold. Moreover, the cement/dexamethasone-loaded PLGA scaffold had a lower drug release compared to pure PLGA. Besides, a higher level of PLGA loading led to an increase in the drug release rate.

Conclusion:

 According to the results, different weight percentages of dexamethasone-loaded PLGA microspheres incorporated into CPC showed differences in the release time.

Our aims were to prepare microspheres labelled with radioactive astatine as brachytherapy seeds and to confirm the antitumor ability of these microspheres.

Chitosan-collagen composite microspheres (CCMs) were synthesized through an emulsification crosslink reaction and radiolabelled with 211At using the chloramine-T method. Radiation stability was assessed in both phosphate-buffered saline and blood serum. The in vivo distribution and therapeutic effects were evaluated in BALB/c nude mice with implanted tumours.

CCMs showed ideal morphological characteristics (diameter of 7.5-15 μm) and acceptable radiation stability (73.99% in PBS and 72.56% in serum after 16 hours). The in vivo biodistribution analysis demonstrated that 211At-CCMs were highly localized in tumour tissue. The therapeutic efficacy of 211At-CCMs when intratumorally injected into a cervical tumour model was assessed. Fourteen days after a single-dose treatment with 211At-CCMs, significantly retarded tumour volume growth was observed.

211At-CCM brachytherapy has the potential to provide an alternative solution for tumour treatment.

Hepatocellular carcinoma (HCC) is currently the fourth most common malignant tumor and the second most fatal tumor in China, posing serious threats to the health and life of individuals.

This retrospective study aimed to investigate the treatment benefits and side effects of transarterial chemoembolization with drug-eluting bead microspheres (DEB-TACE) for HCC patients with conventional TACE (cTACE) resistance.

A total of 17 HCC patients with cTACE resistance, treated by DEB-TACE, were retrospectively analyzed from July 2017 to December 2019. According to the modified response evaluation criteria in solid tumors (mRECIST), the efficacy of treatment was classified into complete remission (CR), partial remission (PR), stable disease (SD), and progressive disease (PD), and the objective remission rate (ORR) and the disease control rate (DCR) were also measured at 6 and 12 weeks post-DEB-TACE treatment. Changes in liver enzymes, routine blood tests, and alpha-fetoprotein (AFP) levels were also documented. Besides, the patients’ adverse reactions were observed within one week after surgery to assess the safety of DEB-TACE therapy.

In patients with cTACE resistance, the CR, PR, SD, PD, ORR, and DCR were 0, 35.29%, 47.06%, 17.65%, 35.29%, and 82.35% at six weeks after DEB-TACE and 5.88%, 47.06%, 29.41%, 17.65%, 52.94%, and 82.35% after 12 weeks, respectively. In the first week after DEB-TACE, the levels of alanine aminotransferase, aspartate aminotransferase, total bilirubin, and white blood cells elevated temporarily (P < 0.05), and side effects, such as slight pain, fever, nausea, and vomiting, occurred after surgery. Following liver protection and symptomatic treatment, the patients recovered well.

Based on the results of this study, DEB-TACE has treatment benefits and few side effects for HCC patients with cTACE resistance.

Peptic ulcer is one of the most common gastrointestinal problems diagnosed all over the world. The aim of the present study is to develop floating microballoons of Rhynchosia densiflora (Roth) DC leaf extract and to evaluate its peptic ulcer activity. An ethanolic extract of R. densiflora (Roth) DC leaves was prepared by Soxhlet extraction and subjected to phytochemical analysis. Microballoons loaded with ethanolic extract of R. densiflora leaf were developed by solvent evaporation method and characterized by optical microscopy, floating time, and release characteristics. Acute oral toxicity study of microballons was carried out following OECD guidelines 423 and antiulcer activity was performed by pylorus ligation, indomethacin and cystamine induced duodenal ulcer methods. R. densiflora extract was found to contain glycosides, proteins, flavonoids, phenolic compounds, tannins and saponins. The particle size of microballoons of R. densiflora extract was found to be in the range of 300 μm. Acute toxicity studies of microballoons did not produce any toxic symptoms and mortality in animals, hence 100 and 200 mg/kg concentrations were selected to screen antiulcer activity. Both the doses showed significant gastric ulcer healing effect and gastric antisecretory effect in pylorus ligated rats, gastric cytoprotective effect in indomethacin induced gastric ulcer and also produced a significant reduction in duodenal ulcers. Dose of 200 mg/kg showed highly significant antiulcer activity than 100 mg/kg. Thus, it is concluded that floating microballoons loaded with R. densiflora extract significantly reduced gastric acid secretion, increased healing of gastric ulcers and also prevent the duodenal ulcers in rats.

Solubility is an important physicochemical factor for any drug molecule that affects its absorption along with its therapeutic effectiveness. Drug absorption is predominantly dependent upon its prompt dissolution. In the case of poorly water-soluble drugs, dissolution is the rate-limiting step in the process of drug absorption. Microspheres were prepared by solvent evaporation method using polymers namely Eudragit L100 and Eudragit RL100. Direct compression technique was used for the preparation of tablets. Tablets were prepared with MCC and PVP K-30 as polymers using an 8mm punch on a rotary press machine with a constant force. Microspheres and the prepared tablets were evaluated using various evaluation tests. The prepared microspheres showed >80% entrapment efficiency and percent yield. Batch F3 exhibited the highest drug release up to 98.30%. Fourier transform infrared (FT-IR) studies revealed no drug–polymer interaction. The results of SEM exhibited that the microspheres are spherical in shape with an average size 5µm. The result of all batches was within an acceptable limit. F2 batch tablet showed a higher drug release of 98.30% as compared with other batches. It was concluded that microcrystalline cellulose or PVP K-30, when used separately, caused retardation in drug release, whereas when used in combination (1:1) it achieved drug release in a controlled manner.

Today, there is an urgent need to develop a three-dimentional culture systems mimicking native in vivo condition in order to screen potency of drugs and possibly any genetic alterations in tumor cells. Due to the existence of limitations in animal models, the development of three dimensional systems is highly recommended. To this end, we encapsulated human colon adenocarcinoma cell line HT29 with alginate-poly-L-lysine (Alg-PLL) microspheres and the rate of epithelial-mesenchymal transition was monitored.

Cells were randomly divided into three groups; control, alginate and Alg-PLL. To encapsulate cells, we mixed HT-29 cells (1 × 106) with 1 mL of 0.05% PLL and 1% Alg mixture and electrosprayed into CaCl2 solution by using a high-voltage power. Cells from all groups were maintained at 37˚C in a humidified atmosphere containing 5% CO2 for 7 days. Cell viability was assessed by MTT assay. To monitor the stemness feature, we measured the transcription of genes such as Snail, Zeb, and Vimentin by using real-time PCR analysis.

Addition of PLL to Alg in a hallowed state increased the cell survival rate compared to the control and Alg groups (P<0.05). Cells inside Alg-PLL tended to form microcellular aggregates while in Alg microspheres an even distribution of HT-29 cells was found. Real-time PCR analysis showed the up-regulation of Snail, Zeb, and Vimentin in Alg-PLL microspheres compared to the other groups, showing the acquisition of stemness feature (P<0.05).

This study showed that hallow Alg-PLL microspheres increased the epithelialmesenchymal transition rate after 7 days in in vitro condition. Such approaches could be touted as appropriate in vitro models for drug screening.

Cytarabine is the drug of choice for treatment of leukemia. However, many formulations have been prepared, due to certain limitations they could not prove to be effective ones, therefore magnetic microspheres are formulated as they minimize the Reticuloendothelial clearance and target site specificity can be increased. The current study aimed to utilize nanotechnology to develop magnetic microspheres. Magnetic microspheres of cytarabine were prepared using two polymers are chitosan and sodium alginate by the continuous solvent evaporation method. Optimization was done and nine different formulations were prepared. Particle sizes, encapsulation efficiency, magnetic responsiveness, in vitro release of all the formulations were determined. The studies demonstrated that F7 was the best formulation and drug can thus be reached to the targeted site as magnetic responsiveness was also good. Novel magnetic microspheres were developed with less Reticuloendothelial clearance and target site specificity; however, further clinical investigations are necessary to evaluate its therapeutic effectiveness.

Sustained release of thermal-instable and water-soluble drugs with low molecule weight is a challenge. In this study, sodium bicarbonate was encapsulated in ethyl cellulose microspheres by a novel solid-in-oil-in-oil (S/O/O) emulsification method using acetonitrile/soybean oil as new solvent pairs. Properties of the microspheres such as size, recovery rate, morphology, drug content, and drug release behavior were evaluated to investigate the suitable preparation techniques. In the case of that the ratio of the internal and external oil phase was 1: 9, Tween 80 as a stabilizer resulted in the highest drug content (2.68%) and a good spherical shape of microspheres. After the ratio increased to 1: 4, the microspheres using Tween 80 as the stabilizer also had high drug content (1.96%) and exhibited a sustained release behavior, with 70% of drug released within 12 h and a sustained release of more than 40 h. Otherwise, different emulsification temperatures at which acetonitrile was evaporated could influence the drug release behaviour of microspheres obtained. This novel method is a potential and effective method to achieve the encapsulation and the sustained release of thermal-instable and water-soluble drugs with low molecule weight.

Nanoparticles are being used for construction of complex and higher-order functional structures and metamaterials with applications in nanophotonics, information storage and biomedicine, to name a few. These innovations are briefly discussed within the context of future diagnostic and nanomedicine platform technologies and their possible self-assembly in vivo.

Microspheres formulated from poly (D,L-lactic-co-glycolide) (PLGA), a biodegradable polymer, have been extensively evaluated as a drug delivery system. In this study, the preparation, characterization and drug release properties of the PLGA microspheres were evaluated. Simvastatin (SIM)-loaded PLGA microspheres were prepared by oil-in-water emulsion/solvent evaporation method. The microspheres were then frozen to −80 °C, they were freeze dried for 24 h. Characterization of SIM-loaded PLGA microspheres was evaluated by X-ray diffraction analysis, Fourier transform infrared spectroscopy analysis, and scanning electron microscopy (SEM). Drug release potential was evaluated by UV-spectrophotometry. The experimental results revealed that SIM-loaded PLGA microspheres can be successfully obtained through solvent evaporation method with appropriate morphologic characteristics and high encapsulation efficiency. The drug release characteristic of the microspheres ascertained that the burst release was about 27% for SIM-loaded microspheres, which occurred within the first 6 days after maintaining the microspheres in phosphate buffer saline (PBS). Also, the microspheres successfully presented a slow release and the duration of the release lasted for more than 20 days. The drug release profile confirmed a burst release was about 27% for SIM-loaded microspheres, which occurred within the first 6 days after maintaining the microspheres in PBS. It can be concluded that SIM-loaded PLGA microspheres hold great promise for using as a drug-delivery system in biomedical applications, especially in drug delivery systems and tissue engineering.

Targeted drug delivery to colon would ensure direct treatment at the disease site, decrease in dose administration and reduction side effects improved drug utilization.. The purpose of this research was to decrease gastric side effects of piroxicam by formulating microspheres of alginate and algino-pectinate beads of the drug.. Ionotropic gelation was used to entrap piroxicam into alginate and algino-pectinate mucoadhesive microspheres as a potential drug carrier for oral delivery of piroxicam. Microparticles with different drug to polymers ratio were prepared and characterized by encapsulation efficiency, particle size, DSC (differential scanning calorimetric), mucoadhesive property, gastroretentive time and drug release studies.. The best drug to polymer ratio of microparticles was 1:2.5 (F1) with Na-Alg and 1:7.5 (F4) with Alg-Na with pectin, respectively. The microparticles F1 and F4 showed 28.80%, 50.01% loading efficiency, 82.57%, 82.31% production yield and 945.4, 899.91 µm mean particle size. DSC showed stable character of piroxicam in drug-loaded microparticles and revealed amorphous form. It was found that microparticles (Na-Alg) prepared had faster release and microparticles (Alg-Na and pectin mixture) prepared had slower release than untreated piroxicam (P < 0.05). Microparticles (mixture of Na-Alg and pectin) exhibited very good percentage of mucoadhesion and flowability properties. Mucoadhesion strength and retention time study showed better retention of piroxicam microparticles in intestine. Besides, there was a significant higher retention of mucoadhesive microparticles in upper GI tract.. Algino-pectinate mucoadhesive formulations exhibited promising properties of a sustained release form for piroxicam and provided distinct tissue protection in stomach..

Context: Biocompatible polymers are potentially effective for dental infections as delivery carriers of disinfectants or antibiotics into the root canal system (RCS). This study aimed to review polymeric microspheres enabling a controlled release of endodontic medicaments..Evidence Acquisition: A literature search was carried out in the PubMed database (May 2013) using the following keywords: “poly lactic-co-glycolic acid or PLGA”, “polymer microplate”, “encapsulate”, “drug delivery”, “controlled release”, “antibiotic”, “gentamycin”, and “amoxicillin”. We intended to find articles on the application of polymer microparticles for delivery and release of drugs in dental infections or articles discussing factors affecting the properties of these materials.. Seventeen articles were found evaluating the controlled release of the drugs for dental purposes; out of them, in 5 in vitro studies, polymer microspheres had been produced for root canal disinfection. Seven articles had investigated the properties of polymer microspheres and the factors influencing drug release by them.. Drug-loaded polymer microspheres may be used successfully as delivery carriers for controlled release of antibiotics into the root canal system. The efficacy and success rate of this method must be tested in animal models and then clinical trials..

Triptorelin is a superagonist decapeptide analogue of GnRH, which has higher binding affinity for the GnRH receptors, a prolonged half-life and therefore a greater potency, 100 times more than GnRH. Different triptorelin controlled release formulations are available in the market. In this study, triptorelin microspheres were successfully prepared using poly lactide (PLA) and poly ethylene glycol (PEG) blends with different ratios and different techniques. The effect of various factors on surface morphology, drug loading, particle size, size distribution, in vitro release and thermal analysis were evaluated. The particle size diameter was ranged from 62 to 145 μm. The impact of oil phase volume on the particle size was the greatest. The optimum drug loading (6.8 or 7.9%) was achieved when the concentration of PEG was 10% or the pH of the system was at isoelectric pH of the external continuous phase, respectively. All the formulations showed continuous drug release with a small burst release. It can be concluded that both diffusion and erosion mechanism contributed in drug release.

The purpose of this study was to prepare and characterize nimodipine loaded microspheres using ethyl cellulose (EC) as a carrier polymer through an emulsion solvent evaporation method. These evaluations characterized the pattern of drug release from prepared microspheres. Nimodipin loaded microspheres were prepared using an emulsification solvent evaporation method. The effect of process variables such as stirring rate, drug polymer ratio in the organic phase, the viscosity of the dispersed phase and the emulsifier concentration, on the morphology of microspheres, particle size distribution, drug content and in vitro release profile of nimodipine were investigated. The prepared microspheres were spherical with smooth surface. The mean diameter of microspheres decreased with increasing the concentration of the emulsifier in the continuous phase and stirring rate of the medium. However, increasing the viscosity of the dispersed organic phase increased the particle size of microspheres. Both the drug and polymer concentration in the organic phase increased the entrapment of nimodipine in ethyl cellulose microspheres. Drug content of the microspheres was lowered by increasing the viscosity of the dispersed phase and increasing the concentration of poly vinyl alcohol. The rate of drug release from microspheres was directly influenced by the drug to polymer ratio, as any increase in this ratio allowed the higher release rates from microspheres. The higher  the polymer concentration the lower was the rate of drug release from microspheres.