# Factorial Design−Driven Optimization of Zein−Chitosan Nanoparticles for Oral Delivery of Silibinin

## TL;DR

Researchers optimized nanoparticles for delivering silibinin, a poorly soluble compound, using a factorial design to improve oral bioavailability and effectiveness.

## Contribution

A factorial design approach was used to systematically optimize zein-chitosan nanoparticles for oral delivery of silibinin.

## Key findings

- Optimized nanoparticles had a mean diameter of ~145 nm, low PDI, high zeta potential, and ~90% encapsulation efficiency.
- Zein and chitosan concentrations significantly influenced particle size and surface charge.
- Nanoencapsulation modulated cytotoxicity in cervical cancer cell lines in a concentration-dependent manner.

## Abstract

Silibinin (SLB) is a poorly water-soluble flavonolignan
with relevant
therapeutic potential but limited oral bioavailability. In this study,
SLB-loaded zein−chitosan nanoparticles (SLB-ZNP) were developed
by nanoprecipitation and optimized using a full 24 factorial
design to investigate the effects of zein concentration, chitosan
concentration, incubation time, and organic-to-water ratio on particle
size, polydispersity index (PDI), zeta potential, and encapsulation
efficiency. The factorial approach enabled systematic evaluation of
the most influential variables and their interactions, with zein and
chitosan concentrations exerting major effects on particle size and
surface charge, while the organic-to-water ratio significantly affected
particle size distribution. The optimized formulation produced nanoparticles
with a mean diameter of approximately 145 nm, low PDI (∼0.19),
high positive zeta potential (∼+40 mV), and high encapsulation
efficiency (∼90%). Transmission electron microscopy revealed
spherical and homogeneous nanoparticles, with enhanced structural
organization upon SLB incorporation. In vitro cytotoxicity assays
in HeLa and SiHa cervical cancer cell lines showed that nanoencapsulation
modulates carrier-associated cytotoxicity in a cell line- and concentration-dependent
manner. Overall, this study demonstrates the utility of factorial
design as a formulation-centered strategy for engineering zein−chitosan
nanoparticles with well-defined physicochemical and in vitro properties.