Layer-by-layer hyaluronic acid/chitosan polyelectrolyte coated mesoporous silica nanoparticles as pH-responsive nanocontainers for optical bleaching of cellulose fabrics

• Polyelectrolyte coated mesoporous silica nanocontainers were employed as an encapsulation material for an optical brightener, CBSX.
• They exhibit high encapsulation efficiency and excellent pH responsiviness.
• The optical bleaching of cellulose fabrics with nanocontainers revealed high whiteness index and total color change.

Polyelectrolyte multilayer (PEM) films composed of two natural polysaccharides (hyaluronic acid and chitosan) were deposited through layer-by-layer (LbL) assembly on top of biocompatible mesoporous silica nanoparticles (MSNPs). Polyelectrolyte multilayer coated mesoporous silica nanoparticles (PEM-MSNPs) were characterized by using attenuated total reflection–fourier transform infrared spectroscopy (ATR–FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherms, UV–vis and fluorescence spectrophotometer. A commercially available and industrially used optical brightener, 4,4′-distyrylbiphenyl sulfonate sodium salt (CBSX) was loaded into nanocontainers (CBSX@PEM-MSNPs) to evaluate their use for the pH-sensitive release. The controlled release of CBSX from nanocontainers in response to pH is monitored by using UV–vis and fluorescence spectrophotometer in water and the almost 100% of encapsulated CBSX is released within 2 h at pH 7. The increase in both whiteness and total color change at pH 7 on a cellulose fabric demonstrates the great potential of nanocontainers as pH-sensitive whitening agents for optical bleaching of cellulose fabrics.