scholarly journals Fabrication of Flocculation-Resistant pH/Ionic Strength/Temperature Multiresponsive Hollow Microspheres and Their Controlled Release

2011 ◽  
Vol 9 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Bin Mu ◽  
Peng Liu ◽  
Xiaorui Li ◽  
Pengcheng Du ◽  
Yun Dong ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Controlled Release ◽  
Hollow Microspheres

scholarly journals SWELLING BEHAVIOR OF POLY (AAM_MA) HYDROGEL MATRIX AND STUDY EFFECTS PH AND IONIC STRENGTH, ENFORCEMENT IN CONTROLLED RELEASE SYSTEM

2018 ◽  
Vol 10 (6) ◽  
pp. 318
Author(s):  
Faiq F. Karam ◽  
Asawer A. Mhammed Alzayd
Keyword(s):  
Free Radical ◽  
Ionic Strength ◽  
Controlled Release ◽  
Radical Polymerization ◽  
Free Radical Polymerization ◽  
Swelling Behavior ◽  
Charge Ratio ◽  
Thermal Gravimetric ◽  
Release System ◽  
Negative Effect

Objective: The objective of this study was to estimate the performance of Acrylamide-malice acid (AAM_MA) hydrogel preparatory by free radical polymerization to loading/release Atenolol and Ciprofloxacin drugs from aqueous solution to be used in a controlled release system.Methods: Free radical polymerization method has been used to prepare (AAM-MA) hydrogel. The prepared hydrogel was characterized by Fourier transform infrared (FTIR), Thermal Gravimetric Analysis/Derivative Thermal Gravimetric (TGA/DTG) and Field Emission Scanning Electron Microscopy (FE-SEM) techniques. The pH-dependent swelling behavior was investigated in addition to the effective ionic strength on adsorption and release system of the drug in vitro.Results: Results showed that the highest swelling ration in pH=7.4 and the same value of pH for the release of the drug. Thermal analysis test for prepared hydrogel showed good thermal stability. The hydrogel showed a negative effect with an increase saline contact Calcium carbonate appeared to have highly effect on releasing drugs from the polymeric network.Conclusion: Higher ability of poly (AAM-MA) hydrogel to act as a carrier for the Ciprofloxacin and Atenolol with highest swelling and releasing under following conditions: at pH 7.4, at temperature 37 °C and the effect of ionic strength (charge/ratio) which indicate that the smaller radius have less effect on release and the largest charge have negative effect on release ratio that attributed to cation formation inter and intra complex surface hydrogel. 

Environment-friendly stimulus-sensitive polyurethanes based on cationic aminoglycosides for the controlled release of phytohormones

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Manuel Palencia ◽  
Mayra Mora ◽  
Tulio A. Lerma
Keyword(s):  
Ionic Strength ◽  
Controlled Release ◽  
Polymeric Materials ◽  
Production Costs ◽  
Naphthalene Acetic Acid ◽  
Social Implication ◽  
Step Method ◽  
Environment Friendly ◽  
Content Type ◽  
Practical Implications

PurposeControlled release systems are an efficient alternative for the effective use of agricultural supplies. Among the most versatile controlled release systems are intelligent or stimulus-sensitive polymeric materials, since these materials are multipurpose and adaptable alternatives that offer great adaptability for agricultural applications. The objective of this work was to develop stimulus-sensitive polyurethanes (PUs) based on cationic aminoglycosides (CAG) to be used as an active phase for the manufacture of systems for the controlled release of phytohormones such as naphthalene acetic acid (NAA).Design/methodology/approachThe synthesis of stimulus-sensitive PUs was carried out by a polycondensation reaction using CAGs and methylene diphenyl isocyanate (MDI) as precursors. The NAA retention and release experiments were performed at different pH values and ionic forces to include the acidity and salinity of agricultural soils.FindingsThe results demonstrate that PUs can be obtained from CAG and MDI using the one-step method. The retention of NAA increased as the CAG content increased in the polymer structure, while it is seen that the effect of pH is weak compared to the effect of ionic strength. On the other hand, the release of NAA from cationic PUs can be accomplished by small changes in ionic strength that are mainly affected by the composition of the PU and the pH. The results suggest that, for developed systems, retention and release of NAA is affected by other interaction mechanisms that could probably be related to p-aromatic interactions.Research limitations/implicationsFindings are limited to controlled conditions and the expanding of results to extensive crops should be analyzed in next research studies.Practical implicationsThe practical implications of this study are improving of control for the dosage of phytohormones in stake propagation crops, greenhouse crops, optimization of reseeding operations, among others.Social implicationsThe social implication of this study is reduction of pollution by addition of excess of NAA, in consequence, production costs are decreased.Originality/valueOriginality and value of this research is the use of PUs based on CAG, and in consequence, the possibility to build novel environment-friendly systems for phytohormone dosage.

Superparamagnetic pH-sensitive multilayer hybrid hollow microspheres for targeted controlled release

2010 ◽  
Vol 48 (14) ◽  
pp. 3135-3144 ◽  
Author(s):  
Bin Mu ◽  
Peng Liu ◽  
Yun Dong ◽  
Chunyin Lu ◽  
Xueli Wu
Keyword(s):  
Controlled Release ◽  
Ph Sensitive ◽  
Hollow Microspheres

CaCO3/Tetraethylenepentamine–Graphene Hollow Microspheres as Biocompatible Bone Drug Carriers for Controlled Release

2016 ◽  
Vol 8 (44) ◽  
pp. 30027-30036 ◽  
Author(s):  
Jie Li ◽  
Hongkun Jiang ◽  
Xiao Ouyang ◽  
Shihui Han ◽  
Jun Wang ◽  
...  
Keyword(s):  
Controlled Release ◽  
Drug Carriers ◽  
Hollow Microspheres

The ionic strength dependence of chromatin folding

1978 ◽  
Vol 36 (2) ◽  
pp. 220-221
Author(s):  
F. Thoma ◽  
TH. Koller
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Ionic Strength ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Carbon Supports ◽  
Ionic Strength Dependence ◽  
Chromatin Folding ◽  
Strength Dependence ◽  
Preparation Techniques

Under a variety of electron microscope specimen preparation techniques different forms of chromatin appearance can be distinguished: beads-on-a-string, a 100 Å nucleofilament, a 250 Å fiber and a compact 300 to 500 Å fiber.Using a standardized specimen preparation technique we wanted to find out whether there is any relation between these different forms of chromatin or not. We show that with increasing ionic strength a chromatin fiber consisting of a row of nucleo- somes progressively folds up into a solenoid-like structure with a diameter of about 300 Å.For the preparation of chromatin for electron microscopy the avoidance of stretching artifacts during adsorption to the carbon supports is of utmost importance. The samples are fixed with 0.1% glutaraldehyde at 4°C for at least 12 hrs. The material was usually examined between 24 and 48 hrs after the onset of fixation.

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