β-Ga2O3:Cr3+ nanoparticle: A new platform with near infrared photoluminescence for drug targeting delivery and bio-imaging simultaneously

Multifunctional nanoparticles which integrate the therapeutic agents and bio-imaging agents into one carrier are emerging as a promising therapeutic platform. Herein, GaOOH:Cr 3+ was firstly synthesized using improved hydrothermal method (atmospheric pressure, 95   °C), and by manipulating the pH of the reaction medium, GaOOH:Cr 3+ with different sizes (125.70   nm, 200.60   nm and 313.90   nm) were synthesized. Then β-Ga 2 O 3 :Cr 3+ nanoparticles with porous structures were developed as a result of the calcination of GaOOH:Cr 3+ . The fabricated, porous β-Ga 2 O 3 :Cr 3+ nanoparticles could effectively absorb doxorubicin hydrochloride (DOX) (loading rate: 8% approximately) and had near infrared photoluminescence with a 695   nm emission. Furthermore, β-Ga 2 O 3 :Cr 3+ nanoparticles were coated with l -Cys modified hyaluronic acid (HA-Cys) by exploiting the electrostatic interaction and the cross-link effect of disulfide bond to improve the stability. The DOX loaded HA-Cys coated β-Ga 2 O 3 :Cr 3+ nanoparticles (HA/β-Ga 2 O 3 :Cr 3+ /DOX) showed an oxidation–reduction sensitive drug release behavior. The HA-Cys coated β-Ga 2 O 3 :Cr 3+ nanoparticles showed a low cytotoxicity on MCF-7 and Hela cell lines. The cellular uptake of HA/β-Ga 2 O 3 :Cr 3+ /DOX using the near infrared photoluminescence of β-Ga 2 O 3 :Cr 3+ nanoparticles and the fluorescence of DOX demonstrated the HA/β-Ga 2 O 3 :Cr 3+ /DOX could internalize into tumor cells quickly, which was affected by the size and shape of β-Ga 2 O 3 :Cr 3+ nanoparticles.