Mesoporous silica nanoparticles (MSN) have been widely used for drug delivery due to their large specific surface area and excellent biocompatibility. However, the mesoporous structure of MSN would lead to the inevitable “premature release” of the drugs, and therefore the modification of MSN for controlled delivery seems to be a necessary step. Herein, chitosan (CS) was used for the surface functionalization of MSN via amidation reaction, and the introduced CS could function as a “gatekeeper” and the drug of methotrexate (MTX) might be encapsulated in the mesopores of MSN. As a result, the “premature release” of the encapsulated MTX could be effectively circumvented with the aid of the CS cap. More importantly, the drug delivery from the hybrid of MSN and CS (MSN/CS) can be endowed with pH-sensitivity by the introduction of CS because the amide bonding between CS and MSN is highly pH-sensitive. The cumulative release of MTX from the MSN/CS is more pronounced at pH 5.0 (80.86%) than those at pH 6.8 (40.46%) and pH 7.4 (18.25%).

中孔二氧化硅纳米粒子（MSN）由于其大的比表面积和出色的生物相容性而被广泛用于药物输送。但是，MSN的中孔结构将导致药物不可避免的“过早释放”，因此，为了控制递送而对MSN进行修饰似乎是必不可少的步骤。在这里，壳聚糖（CS）用于通过酰胺化反应对MSN进行表面功能化，并且引入的CS可以充当“守门员”，而甲氨蝶呤（MTX）的药物可能被封装在MSN的中孔中。结果，可以借助CS盖有效地避免封装的MTX的“过早释放”。更重要的是，由于CS和MSN之间的酰胺键对pH高度敏感，因此通过引入CS可以使MSN和CS的杂化体（MSN / CS）的药物传递具有pH敏感性。在pH 5.0（80.86％）下，MSX / CS的MTX累积释放比在pH 6.8（40.46％）和pH 7.4（18.25％）时更明显。