Improving the safety efficacy ratio of existing drugs is a current challenge to be addressed rather than the development of novel drugs which involve much expense and time. The efficacy of drugs is affected by a number of factors such as their low aqueous solubility, unequal absorption along the gastrointestinal (GI) tract, risk of degradation in the acidic milieu of the stomach, low permeation of the drugs in the upper GI tract, systematic side effects, etc. This review aims to enlighten readers on the role of pH sensitive hydrogels in drug delivery, their mechanism of action, swelling, and drug release as a function of pH change along the GI tract. The basis for the selection of materials, their structural features, physical and chemical properties, the presence of ionic pendant groups, and the influence of their pK a and pK b values on the ionization, consequent swelling, and targeted drug release are also highlighted.

Potential-dependent adsorption/desorption behavior of perfluorosulfonated ionomer (PFSI) on a platinum electrode was investigated by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM), and electrochemical atomic force microscope (EC-AFM) in a Nafion, that is, PFSI, dispersed aqueous solution without any other electrolyte. PFSI adsorbed on the platinum surface in the potential region between 0.1 and 0.8 V versus Ag/AgCl and desorbed from the surface at 1.1 V where place-exchanged Pt oxide was formed. Once platinum oxide was reduced, PFSI readsorbed on the surface. These processes took place reversibly.

No abstract

No abstract

No abstract