A theranostic nanoparticle system was developed by integrating a chemotherapeutic agent with an “activatable”
fluorescent tracer. The system signals tumor death by monitoring the activity of caspase-3, a product of apoptosis, and
can therefore screen the treatment sensitivity of a particular tumor.
The polymer nanoparticles (Poly [isobutylene-alt-maleic anhydride]) were formed through reprecipitation and contained
paclitaxel, a chemotherapy drug, and fluorescein isothiocyanate, a fluorescent dye. The dye’s fluorescence was quenched
through Förster resonance energy transfer (FRET) by a quencher that was connected to the dye by a peptide chain. With
sizes ranging from 200-250 nm, the nanoparticles were stable for two weeks.
The nanoparticles were tested in vitro with responsive Lewis Lung Carcinoma (LLC) cells and taxane-resistant cells.
Upon cell death by paclitaxel exposure, caspase-3 cleaved the peptide chain connecting the dye and the quencher,
causing the system to fluoresce. When LLC cells were treated with the system, the nanoreporters fluoresced, but when
resistant cells were tested, and when the drug was removed from the system, the nanoreporters did not fluoresce.
Since the system screens if a drug can successfully kill a particular tumor, it offers a novel and promising approach to