Temperature-responsive capsules

Encapsulation of PNIPAM inside non-temperature-sensitive (PSS/PAH) capsules templated on PS cores was achieved by the same ship in a bottle synthesis [37], providing temperature-responsive microcapsules. Encapsulated PNIPAM collapsed when the temperature of the system increased above 34 °C, forming discrete particles inside the capsule, without modification of the shell (Fig. 3.6). This prop-... 

GARCIA, V.E., GHERARDI, M.M., IGLESIAS, M.F., CERQUETTI, M.C. SORDELLI, D.O. (1993) Local and systemic immunity against Streptococcus pneumoniae humoral responses against a non-capsulated temperature-sensitive mutant. FEMS Microbiology Letters, 108, 163-167. 

DSC measurement is based on the heat loss and absorption caused by changes in the sample as a function of the temperature programmed dynamics. The reference cell is an empty aluminum capsule (capsule without the sample). Therefore, when the sample undergoes any change, there is a difference between the temperature of the sample and that of the reference, and this difference is quantihed and converted in thermograms. The response to the analysis is given by the flow of heat as a function of the temperature (Bunjes and Unruh, 2007). 

In this chapter, diverse aqueous assemblies such as tubules, toroids, porous capsules, and helical fibers will be introduced using rigid-flexible block systems. Also, we focus on unique shmuli-responsive features of nanostructures according to the temperature, certain guests, pH, and solvent. 

Dual-responsive polymer-based drug delivery vehicles offer even more versatility. Both temperature and enzyme-responsive micelles were formed from block polymers. While the thermoresponsive properties of the material allow it to be injected and subsequently form a reservoir in the body from where micelles enter the blood stream, the enzyme-responsive component allows triggered degradation of the micelles and release of the drug at the location of the diseased tissue (Garripelli et fl/.,2011). A doubly enzyme-responsive system can be obtained, for example, by designing polymer capsules with a shell that contains two layers. The two layers are degraded by different enzymes thus, proteins entrapped in the outer layer itself can be released upon exposure to the first enzyme, whereas the second enzyme destroys the capsule completely and liberates the proteins entrapped in the cavity of the vehicle (Itoh et al, 2008). 

For temperatures above about 20 K, the metallic resistance thermometers are more sensitive than the nonmetallic resistance thermometers. Temperatures above 20 K can be measured routinely with an industrial-type platinum resistance thermometer with an accuracy of better than 100 mK with time responses somewhat better than 1 s. Accuracy at the millidegree level requires a precision capsule type platinum resistance thermometer and careful calibration. 

A method to prepare well-defined responsive microcapsules and nanocapsules with engineered walls is reported. A decomposable colloidal template is coated by polyelectrolyte multilayers, and after core removal a hollow capsule, refillable with drugs, is obtained. The release of the capsule as well as mechanical properties can be tuned by adjusting pH and temperature. 

---