Rheological Measurement of the Gelation Temperature of Thermoresponsive Hydrogels: A Tutorial Using Pluronic F127

2021 ◽  
Author(s):  
Haipeng Zhang ◽  
Rongguo Ren ◽  
Dong Wang ◽  
Sangjin Ryu
Keyword(s):  
Pluronic F127 ◽  
Gelation Temperature ◽  
Rheological Measurement ◽  
Thermoresponsive Hydrogels

Rheological Measurement of the Gelation Temperature of Thermoresponsive Hydrogels: A Tutorial Using Pluronic F127

2020 ◽  
Author(s):  
Haipeng Zhang ◽  
Sangjin Ryu ◽  
Rongguo Ren ◽  
Dong Wang
Keyword(s):  
Oscillation Frequency ◽  
Network Formation ◽  
Loss Modulus ◽  
Pluronic F127 ◽  
Local Drug Delivery ◽  
Temperature Threshold ◽  
Gelation Temperature ◽  
Rheological Measurement ◽  
Thermoresponsive Hydrogel ◽  
Thermoresponsive Hydrogels

Abstract Pluronic F127 is a thermoresponsive hydrogel well used for various pharmaceutical applications. An emulsion of F127 can be gelated by heating the mixture, and this thermoresponsive gelation property enables local drug delivery. Thus, it is important to measure the gelation temeperature of F127 and similar thermoresponsive hydrogels for characterizing their gelation process for such applications. Gelation temperature (Tgel) is a temperature threshold indicating the presence of network formation in F127 and similar thermoresponsive hydrogel materials. A widely used method for Tgel measurement is to measure Tgel based on changes in the storage modulus (G′) and loss modulus (G″) of the hydrogel with respect to temperature. However, this rheological measurement requires careful choices of measurement conditions. In this paper, we present the detailed tuning steps and results of our rheological Tgel measurement of F127 using a rotational rheometer as a tutorial for other researchers. First, oscillation strain sweep measurements were performed to determine an optimum strain value in the linear viscoelastic region. Second, oscillation frequency sweep measurements were conducted to choose a reasonable oscillation frequency value. Third, G′ and G″ of F127 (25% w/v) were measured in the oscillation temperature sweep mode for the temperature range of 5°C to 45°C with the determined shear strain (0.1%) and oscillation frequency (1 rad/s). Last, Tgel was determined based on the crossover between measured G′ and G″ curves. Additionally, we compared the temperature sweep mode and the temperature ramp mode, and investigated effects of preshearing duration on repeated G′-G″ measurement and Tgel determination. The summarized procedure can be used as a reference to perform reliable and repeatable rheological Tgel measurement of thermoresponsive hydrogel materials.

scholarly journals Mucoadhesive In Situ Rectal Gel Loaded with Rifampicin: Strategy to Improve Bioavailability and Alleviate Liver Toxicity

Pharmaceutics ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 336
Author(s):  
Fakhria Al-Joufi ◽  
Mohammed Elmowafy ◽  
Nabil K. Alruwaili ◽  
Khalid S. Alharbi ◽  
Khaled Shalaby ◽  
...  
Keyword(s):  
Liver Toxicity ◽  
Gel Strength ◽  
Pluronic F127 ◽  
Oral Drug ◽  
Gelation Temperature ◽  
Mucoadhesive Polymers ◽  
Drug Polymer Interaction ◽  
Polymer Interaction

Although it is a front-line in tuberculosis treatment, rifampicin (RF) exhibits poor oral bioavailability and hepatotoxicity. Rectal mucoadhesive and in situ rectal gels were developed to overcome drug drawbacks. A RF/polyethylene glycol 6000 co-precipitate was first prepared in different ratios. Based on the drug solubility, the selected ratio was investigated for drug/polymer interaction and then incorporated into in situ rectal gels using Pluronic F127 (15%) and Pluronic F68 (10%) as a gel base and mucoadhesive polymers (HPMC, sodium alginate and chitosan). The formulations were assessed for gelation temperature and gel strength. The selected formulation was investigated for in vivo assessments. The results showed that a 1:1 drug/polymer ratio exhibited satisfying solubility with the recorded drug/polymer interaction. Depending on their concentrations, adding mucoadhesive polymers shifted the gelation temperature to lower temperatures and improved the gel strength. The selected formulation (F4) did not exhibit any anal leakage or marked rectal irritation. Using a validated chromatographic analytical method, F4 exhibited higher drug absorption with a 3.38-fold and 1.74-fold higher bioavailability when compared to oral drug suspension and solid suppositories, respectively. Toxicity studies showed unnoticeable hepatic injury in terms of biochemical, histopathological and immunohistochemical examinations. Together, F4 showed a potential of enhanced performance and also offered lower hepatic toxicity, thus offering an encouraging therapeutic alternative.

scholarly journals Release of a Wound-Healing Agent from PLGA Microspheres in a Thermosensitive Gel

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
H. A. Machado ◽  
J. J. Abercrombie ◽  
T. You ◽  
P. P. DeLuca ◽  
K. P. Leung
Keyword(s):  
Antimicrobial Activity ◽  
Drug Loading ◽  
Control Release ◽  
Cell System ◽  
Pluronic F127 ◽  
Poloxamer 407 ◽  
Gelation Temperature ◽  
Release Process ◽  
Broth Microdilution Method

The purpose of this research was to develop a topical microsphere delivery system in a thermosensitive 20% poloxamer 407 gel (Pluronic F127) to control release of KSL-W, a cationic antimicrobial decapeptide, for a period of 4–7 days for potential application in combat related injuries. KSL-W loaded microsphere formulations were prepared by a solvent extraction-evaporation method (water-oil-water), with poly (D,L-lactic-co-glycolic acid) (PLGA) (50 : 50, low-weight, and hydrophilic end) as the polymeric system. After optimization of the process, three formulations (A, B, and C) were prepared with different organic to water ratio of the primary emulsion while maintaining other components and manufacturing parameters constant. Formulations were characterized for surface morphology, porous nature, drug loading,in vitrodrug release, and antimicrobial activity. Microspheres containing 20% peptide with porous surfaces and internal structure were prepared in satisfactory yields and in sizes varying from 25 to 50 μm. Gels of 20% Pluronic F127, which were liquid at or below 24.6°C and formed transparent films at body temperature, were used as carriers for the microspheres. Rheological studies showed a gelation temperature of 24.6°C for the 20% Pluronic F127 gel alone. Gelation temperature and viscosity of formulations A, B, and C as a function of temperature were very close to those of the carrier. A Franz diffusion cell system was used to study the release of peptide from the microspheres suspended in both, phosphate-buffered saline (PBS) and a 20% Pluronic F127 gel.In vitrorelease of greater than 50% peptide was found in all formulations in both PBS and the gel, and in one formulation there was a release of 75% in both PBS and the gel. Fractions collected from the release process were also tested for bactericidal activity againstStaphylococcus epidermidisusing the broth microdilution method and found to provide effective antimicrobial activity to warrant consideration and testing in animal wound models for treating combat-related injuries.

Optimization and Characterization of Aqueous Micellar Formulations for Ocular Delivery of an Antifungal Drug, Posaconazole

2020 ◽  
Vol 26 (14) ◽  
pp. 1543-1555 ◽  
Author(s):  
Meltem E. Durgun ◽  
Emine Kahraman ◽  
Sevgi Güngör ◽  
Yıldız Özsoy
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Size Distribution ◽  
Encapsulation Efficiency ◽  
Fungal Infections ◽  
In Vitro Release ◽  
Pluronic F127 ◽  
Glycol Succinate ◽  
Vitro Release

Background: Topical therapy is preferred for the management of ocular fungal infections due to its superiorities which include overcoming potential systemic side effects risk of drugs, and targeting of drugs to the site of disease. However, the optimization of effective ocular formulations has always been a major challenge due to restrictions of ocular barriers and physiological conditions. Posaconazole, an antifungal and highly lipophilic agent with broad-spectrum, has been used topically as off-label in the treatment of ocular fungal infections due to its highly lipophilic character. Micellar carriers have the potential to improve the solubility of lipophilic drugs and, overcome ocular barriers. Objective: In the current study, it was aimed optimization of posaconazole loaded micellar formulations to improve aqueous solubility of posaconazole and to characterize the formulations and to investigate the physical stability of these formulations at room temperature (25°C, 60% RH), and accelerated stability (40°C, 75% RH) conditions. Method: Micelles were prepared using a thin-film hydration method. Pre-formulation studies were firstly performed to optimize polymer/surfactant type and to determine their concentration in the formulations. Then, particle size, size distribution, and zeta potential of the micellar formulations were measured by ZetaSizer Nano-ZS. The drug encapsulation efficiency of the micelles was quantified by HPLC. The morphology of the micelles was depicted by AFM. The stability of optimized micelles was evaluated in terms of particle size, size distribution, zeta potential, drug amount and pH for 180 days. In vitro release studies were performed using Franz diffusion cells. Results: Pre-formulation studies indicated that single D-ɑ-tocopheryl polyethylene glycol succinate (TPGS), a combination of it and Pluronic F127/Pluronic F68 are capable of formation of posaconazole loaded micelles at specific concentrations. Optimized micelles with high encapsulation efficiency were less than 20 nm, approximately neutral, stable, and in aspherical shape. Additionally, in vitro release data showed that the release of posaconazole from the micelles was higher than that of suspension. Conclusion: The results revealed that the optimized micellar formulation of posaconazole offers a potential approach for topical ocular administration.

Formulation and Evaluation of Atorvastatin Calcium-Poly-ε-Caprolactone Nanoparticles Loaded Ocular Inserts for Sustained Release and Antiinflammatory Efficacy

2020 ◽  
Vol 21 (15) ◽  
pp. 1688-1698
Author(s):  
Germeen N.S. Girgis
Keyword(s):  
Sustained Release ◽  
In Vitro Release ◽  
Pluronic F127 ◽  
In Vivo Study ◽  
Average Weight ◽  
Drug Release Profile ◽  
Atorvastatin Calcium ◽  
Anti Inflammatory

Purpose: The work was performed to investigate the feasibility of preparing ocular inserts loaded with Poly-ε-Caprolactone (PCL) nanoparticles as a sustained ocular delivery system. Methods: First, Atorvastatin Calcium-Poly-ε-Caprolactone (ATC-PCL) nanoparticles were prepared and characterized. Then, the optimized nanoparticles were loaded within inserts formulated with Methylcellulose (MC) and Polyvinyl Alcohol (PVA) by a solvent casting technique and evaluated physically, for in-vitro drug release profile. Finally, an in-vivo study was performed on the selected formulation to prove non-irritability and sustained ocular anti-inflammatory efficacy compared with free drug-loaded ocuserts. Results: The results revealed (ATC-PCL) nanoparticles prepared with 0.5% pluronic F127 were optimized with 181.72±3.6 nm particle size, 0.12±0.02 (PDI) analysis, -27.4± 0.69 mV zeta potential and 62.41%±4.7% entrapment efficiency. Nanoparticles loaded ocuserts manifested compatibility between drug and formulation polymers. Moreover, formulations complied with average weight 0.055±0.002 to 0.143±0.023 mg, and accepted pH. ATC-PCL nanoparticles loaded inserts prepared by 5% MC showed more sustained, prolonged in-vitro release over 24h. In-vivo study emphasized non-irritability, ocular anti-inflammatory effectiveness represented by smaller lid closure scores, and statistically significant lowering in PMN count after 3h. Conclusion: These findings proposed a possibly simple, new and affordable price technique to prepare promising (ATC-PCL) nanoparticles loaded inserts to achieve sustained release with prolonged antiinflammatory efficacy.

Influence of adding Pluronic F127 in the electrolyte on the morphology, structure and biofilm adhesion of calcium phosphate coatings

2021 ◽  
Vol 56 (14) ◽  
pp. 8427-8438
Author(s):  
Pablo Eduardo Costa dos Santos ◽  
Cristina Ferraz Silva ◽  
Cristiane Xavier Resende ◽  
Zaine Teixeira Camargo
Keyword(s):  
Calcium Phosphate ◽  
Pluronic F127 ◽  
Phosphate Coatings ◽  
Calcium Phosphate Coatings

scholarly journals Effect of pluronic block polymers and N-acetylcysteine culture media additives on growth rate and fatty acid composition of six marine microalgae species

2021 ◽  
Vol 105 (5) ◽  
pp. 2139-2156
Author(s):  
Justine Sauvage ◽  
Gary H. Wikfors ◽  
Xiaoxu Li ◽  
Mark Gluis ◽  
Nancy Nevejan ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Culture Media ◽  
Fatty Acid Content ◽  
Pluronic F127 ◽  
Algal Culture ◽  
Omega 3 ◽  
Chaetoceros Muelleri ◽  
Omega 3 Fatty Acid ◽  
Live Feed ◽  
Chaetoceros Calcitrans

Abstract The efficiency of microalgal biomass production is a determining factor for the economic competitiveness of microalgae-based industries. N-acetylcysteine (NAC) and pluronic block polymers are two compounds of interest as novel culture media constituents because of their respective protective properties against oxidative stress and shear-stress-induced cell damage. Here we quantify the effect of NAC and two pluronic (F127 and F68) culture media additives upon the culture productivity of six marine microalgal species of relevance to the aquaculture industry (four diatoms-Chaetoceros calcitrans, Chaetoceros muelleri, Skeletonema costatum, and Thalassiosira pseudonana; two haptophytes-Tisochrysis lutea and Pavlova salina). Algal culture performance in response to the addition of NAC and pluronic, singly or combined, is dosage- and species-dependent. Combined NAC and pluronic F127 algal culture media additives resulted in specific growth rate increases of 38%, 16%, and 24% for C. calcitrans, C. muelleri, and P. salina, respectively. Enhanced culture productivity for strains belonging to the genus Chaetoceros was paired with an ~27% increase in stationary-phase cell density. For some of the species examined, culture media enrichments with NAC and pluronic resulted in increased omega-3-fatty acid content of the algal biomass. Larval development (i.e., growth and survival) of the Pacific oyster (Crassostrea gigas) was not changed when fed a mixture of microalgae grown in NAC- and F127-supplemented culture medium. Based upon these results, we propose that culture media enrichment with NAC and pluronic F127 is an effective and easily adopted approach to increase algal productivity and enhance the nutritional quality of marine microalgal strains commonly cultured for live-feed applications in aquaculture. Key points • Single and combined NAC and pluronic F127 culture media supplementation significantly enhanced the productivity of Chaetoceros calcitrans and Chaetoceros muelleri cultures. • Culture media enrichments with NAC and F127 can increase omega-3-fatty acid content of algal biomass. • Microalgae grown in NAC- and pluronic F127-supplemented culture media are suitable for live-feed applications.

Fabrication of poly (1, 8-octanediol-co-Pluronic F127 citrate)/chitin nanofibril/bioactive glass (POFC/ChiNF/BG) porous scaffold via directional-freeze-casting

2020 ◽  
Vol 40 (7) ◽  
pp. 591-599
Author(s):  
Yaling Tian ◽  
Kai Liang ◽  
Yali Ji
Keyword(s):  
Bioactive Glass ◽  
Porous Structure ◽  
Pore Structure ◽  
Porous Scaffold ◽  
Pluronic F127 ◽  
Porous Scaffolds ◽  
Freeze Casting ◽  
Promising Candidate ◽  
Complete Replacement

AbstractThe citrate-based thermoset elastomer is a promising candidate for bone scaffold material, but the harsh curing condition made it difficult to fabricate porous structure. Recently, poly (1, 8-octanediol-co-Pluronic F127 citrate) (POFC) porous scaffold was creatively fabricated by chitin nanofibrils (ChiNFs) supported emulsion-freeze-casting. Thanks to the supporting role of ChiNFs, the lamellar pore structure formed by directional freeze-drying was maintained during the subsequent thermocuring. Herein, bioactive glass (BG) was introduced into the POFC porous scaffolds to improve bioactivity. It was found the complete replacement of ChiNF particles with BG particles could not form a stable porous structure; however, existing at least 15 wt% ChiNF could ensure the formation of lamellar pore, and the interlamellar distance increased with BG ratios. Thus, the BG granules did not contribute to the formation of pore structure like ChiNFs, however, they surely endowed the scaffolds with enhanced mechanical properties, improved osteogenesis bioactivity, better cytocompatibility as well as quick degradation rate. Reasonably adjusting BG ratios could balance the requirements of porous structure and bioactivity.

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