Direct photoacoustic measurement of silicon nanoparticle degradation promoted by a polymer coating

Nanomaterials with controllable biodegradation properties respond to the main challenge of cancer nanomedicine to minimise side effects and maximise the delivery efficacy to tumours. These biodegradation properties vary from clear aqueous solutions to protein-abundant biological fluids. A photoacoustic method suitable for in vitro quantification of highly scattering colloids with optical absorption properties is introduced and demonstrated by determination of the degradation rate of laser-synthesized silicon nanoparticles (Si NPs) in turbid serum solutions. In vitro screening of a variety of polymer surface-coatings of Si NPs revealed a stand-alone property of polyallylamine (PAA) to accelerate the Si NP dissolution. PAA-coated Si NP half-life was measured ∼ 100-min in aqueous solutions and slowed down to ∼ 24 h in serum. As-produced PAA-coated Si NPs appeared suitable for blockade of the mononuclear phagocyte system. Pre-treatment with PAA-Si NPs caused 1.4-times reduced uptake of magnetic particles by human THP-1 cells in vitro and a 13-fold increase of the magnetic particle delivery to the B16-F1 xenograft tumours in vivo. The demonstrated photoacoustic method is believed to facilitate design and screening of biodegradable materials suitable for in vivo applications such as controlled drug release.