Inorganic bioactive nanomaterials are attractive for hard tissue regeneration, including nanocomponents for bone replacement composites and nanovehicles for delivering therapeutics. Bioactive glass nanoparticles (BGn) have recently gained potential usefulness as bone and tooth regeneratives. Here we demonstrate the capacity of the BGn with mesopores to load and deliver therapeutic molecules (drugs and particularly genes). Spherical BGn with sizes of 80-90 nm were produced to obtain 3-5 nm sized mesopores through a sono-reacted sol-gel process. A simulated body fluid test of the mesoporous BGn confirmed their excellent apatite forming ability and the cellular toxicity study demonstrated their good cell viability up to 100 μg ml(-1). Small molecules like chemical drug (Na-ampicillin) and gene (small interfering RNA; siRNA) were introduced as model drugs considering the mesopore size of the nanoparticles. Moreover, amine-functionalization allowed switchable surface charge property of the BGn (from -20-30 mV to +20-30 mV). Loading of ampicillin or siRNA saturated within a few hours (~2 h) and reflected the mesopore structure. While the ampicillin released relatively rapidly (~12 h), the siRNA continued to release up to 3 days with almost zero-order kinetics. The siRNA-nanoparticles were easily taken up by the cells, with a transfection efficiency as high as ~80%. The silencing effect of siRNA delivered from the BGn, as examined by using bcl-2 model gene, showed dramatic down-regulation (~15% of control), suggesting the potential use of BGn as a new class of nanovehicles for genes. This, in conjunction with other attractive properties, including size- and mesopore-related high surface area and pore volume, tunable surface chemistry, apatite-forming ability, good cell viability and the possible ion-related stimulatory effects, will potentiate the usefulness of the BGn in hard tissue regeneration.

We report the ability of aminated mesoporous silica nanoparticles (MSN-NH2) with large mesopore space and positive-charged surface to deliver genes within rat mesenchymal stem cells (MSCs). The amine functionalized inorganic nanoparticles were complexed with bone morphogenetic protein-2 (BMP2) plasmid DNA (pDNA) to study their transfection efficiency in MSCs. Intracellular uptake of the complex BMP2 pDNA/MSN-NH2 occurred significantly, with a transfection efficiency of approximately 68%. Furthermore, over 66% of the transfected cells produced BMP2 protein. The osteogenic differentiation of the transfected MSCs was demonstrated by the expression of bone-related genes and proteins including bone sialoprotein, osteopontin, and osteocalcin. The MSN-NH2 delivery vehicle for BMP2 pDNA developed in this study may be a potential gene delivery system for bone tissue regeneration.

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