Theranostic combinatorial drug-loaded coated cubosomes for enhanced targeting and efficacy against cancer cells

Cubosomes, a product of nanobioengineering, are self-structured lipid nanoparticles that act like drug-loaded theranostic probes. Here, we describe a simple method for the preparation of combinatorial drug-loaded cubosomes with, proof-of-principle, therapeutic effect against cancer cells, along with diagnostic capabilities. Anticancer drugs cisplatin and paclitaxel were loaded in the cubosomes in combination. The cubosomes were coated with a layer of poly-Ɛ-lysine, which helped avoid the initial burst release of drug and allowed for a slow and sustained release for better efficacy. Cubosomes were imaged by transmission electron microscope, and their dispersion analyzed in vitro by differential scanning calorimetric and X-ray diffractogram studies. The microscopic images depicted spherical polyangular structures, which are easily distinguishable. The analyses revealed that the drug is uniformly dispersed all through the cubosomes. Further characterization was carried out by zeta-potential measurement, in vitro release, and entrapment efficiency studies. The in vitro studies established that the coating of cubosomes successfully reduced the burst release of drugs initially and confirmed a slow, sustained release over increased time. Comparative cytotoxicity of coated, uncoated, and blank cubosomes was evaluated, using human hepatoma HepG2 cell line, and the formulations were found to be entirely nontoxic, similar to the blank ones. The therapeutic efficiency of the cubosomes against HeLa cells was confirmed by the impedance measurement and fluorescent imaging. Furthermore, the reduction in impedance in cells treated with coated combinatorial cubosomes proved the impairment of HeLa cells, as confirmed by fluorescence microscopy.