Study of the mechanism of cationic drug release increase coated with Surelease
after curing

This paper describes the investigation of the release mechanism of the cationic drug coated with Surelease
after curing compared with nonionic and anionic drug.The release rate of cured propafenone hydrochloride pellets coated with Surelease
was increased significantly compared with uncured ones.The changes in release rate after seal-coating proved the migration of drug into the polymer film.Based on a comparative study of ammonia permeation tests and the impact of ammonia on drug with different properties,it was shown that the change in release of the cationic drug after curing was related to the combination of cationic drug and ammonia in Surelease
.Also,the scanning electron microscopy results showed that curing and dissolution can both prevent polymer film coalescence.During coating,the evaporated ammonia combined with the cationic drug and the polymer film coalesced.However,the combined ammonia could be decomposed during curing and interrupt the coalescence of the polymer-coat,leading to increased release.In an optimized process,the ammonia in the Surelease
can be evaporated quickly and the ionization of the drug will be reduced.All these factors can contribute to the formation of the polymer film.

The Preparation of Cationic Folic Acid and Its Application in Drug Delivery System

The cationic folic acid（CFA） was prepared by introducing triethylenetetramine into folic acid with EDCI/NHS and characterized by IR, NMR and mass spectra. It was found that approximately one of two carboxyls in the folic acid molecule was substituted to form CFA. The conversion of γ-carboxyl is found to be 59% higher than 30% of γ-carboxyl. The CFA and doxorubicin hydrochloride can be loaded on the ionic shell of PTX-encapsulated micelle to form CFA loaded binary drug carrier via static interaction in aqueous solutions. The successful loading was demonstrated by zeta potential measurement and the drug load amount（DLA） of CFA was measured by HPLC. In vitro cytotoxicity results revealed the CFA drug carrier showed higher cytotoxicity to cancer cell MDA-MB-321 than the binary drug carrier without CFA and the positive control, while it showed lower cytotoxicity to normal cell HUVEC than the positive control, and similar cytotoxicity with the binary drug carrier without CFA. These results as well as confocal laser scanning microscopy observation indicate the synthesized CFA drug carrier possesses active tumor-targeting property.

Chiral nanocomposite of sulfobutyl ether-b-cyclodextrin embedded in carbon nanofibers for enantioselective electrochemical discrimination of amlodipine, metoprolol and clenbuterol enantiomers

A highly sensitive and selective electrochemical chiral sensor was developed based on the competitive supramolecular interaction of carbon nanofibers(CNFs)embedded sulfobutyl ether-b-cyclodextrin(SBEb-CD)with optically active cationic drugs at glassy carbon electrode(GCE).The difference in intermolecular hydrogen bonding/stability constant/enantioselectivity coefficient and Gibbs free energy of anionic host SBE-b-CD with enantiomers of amlodipine(R-/S-AML),clenbuterol(R-/S-CBL)and metoprolol(R-/S-MET)as a guest paved the way for efficient discrimination.The proposed sensing platform(CNFs-SBE-b-CD/GCE)could recognize the aforementioned enantiomers based on the discernible difference of peak potential(S/R-AML(△Ep=135 mV),R/S-MET(△Ep=99 mV)and R/S-CBL(△Ep=111 mV).The binding mechanisms and thermodynamic study of the enantiospecific behavior have been investigated using the host-guest chemistry approach inside the nanocavity and results suggest that S-AML,RMET,and R-CBL show stronger stability constants than their antipodes.Formation of the diastereomeric complex was taken as a measure of enantioselectivity and experimental results indicated that anionic SBE-b-CD is a better chiral ligand than neutral cyclodextrins.The fabricated sensor could be a useful lowcost electrochemical tool for molecular recognition of a variety of cationic species not only of drugs but also from other sources.