Synthesis of a fluorescent ethyl cellulose membrane with application in monitoring 1-naphthylacetic acid from controlled release formula

A triple-functional (chemical release properties, physical release properties, and monitoring 1-naphthylacetic acid (NAA) release) ethyl cellulose (EC) membrane, modified with fluorescein 1-naphthylacetic acid ester (FNE) and isophorone diisocyanate (IPDI), was prepared (designated as IECF membrane). Fourier transform infrared analysis was conducted to confirm the grafting of FNE to the EC backbone. The chemical and physical release properties of IECF membrane were investigated. The chemical release traits of NAA were related to the hydrolysis of FNE of IECF membrane which was influenced by the NAA concentration at pH 7.2. The physical release traits of NAA were determined by the permeation of NAA from IECF membrane. So IECF membrane has a considerable ability to form a controlled release formula for coating NAA. Furthermore, the hydrolysis of FNE was associated with the recovery of fluorescent intensity of IECF membrane, making the membrane have the ability to monitor low concentration of NAA.