Multifunctional polyelectrolyte multilayers coated onto Gd2O3:Yb3+,Er3+@MSNs can be used as drug carriers and imaging agents

Abstract

Mesoporous silica nanoparticles (MSNs) were firstly functionalized with upconversion luminescent Gd₂O₃:Yb³⁺,Er³⁺ via the Pechini sol–gel method. Then, polyelectrolyte multilayers (PEM) composed of poly(allyamine hydrochloride) (PAH) and poly(styrene sulfonate) (PSS) were coated onto the Gd₂O₃:Yb³⁺,Er³⁺@MSNs using a layer-by-layer (LbL) technique to achieve the pH-responsive properties of the nanocarriers. PEM@Gd₂O₃:Yb³⁺,Er³⁺@MSNs loaded with doxorubicin hydrochloride (DOX) showed pH-responsive release and higher cytotoxicity towards MCF-7 breast cancer cells in vitro. Nanocomposites functionalized with Gd₂O₃:Yb³⁺,Er³⁺ can serve as T₁-weighted magnetic resonance imaging (MRI) contrast agents. Nanoparticles emitting red signals under 980 nm laser excitation are suitable for use in potential bioimaging applications. The upconversion luminescent (UCL) intensity of PEM-coated nanocomposites can be adjusted by controlling the number of layers of the PAH/PSS coating. The PEM@Gd₂O₃:Yb³⁺,Er³⁺@MSNs can be used as a potential drug delivery system for MRI, UCL imaging, and pH-responsive chemotherapy.