Efficient Active Oxygen Free Radical Generated in Tumor Cell by Loading-(HCONH2)·H2O2 Delivery Nanosystem with Soft-X-ray Radiotherapy

Abstract

Tumor hypoxia is known to result in radiotherapy resistance and traditional radiotherapy using super-hard X-ray irradiation can cause considerable damage to normal tissue. Therefore, formamide peroxide (FPO) with high reactive oxygen content was employed to enhance the oxygen concentration in tumor cells and increase the radio-sensitivity of low-energy soft-X-ray. To improve stability of FPO, FPO is encapsulated into polyacrylic acid (PAA)-coated hollow mesoporous silica nanoparticles (FPO@HMSNs-PAA). On account of the pH-responsiveness of PAA, FPO@HMSNs-PAA will release more FPO in simulated acidic tumor microenvironment (pH 6.50) and subcellular endosomes (pH 5.0) than in simulated normal tissue media (pH 7.40). When exposed to soft-X-ray irradiation, the released FPO decomposes into oxygen and the generated oxygen further formed many reactive oxygen species (ROS), leading to significant tumor cell death. The ROS-mediated cytotoxicity of FPO@HMSNs-PAA was confirmed by ROS-induced green fluorescence in tumor cells. The presented FPO delivery system with soft-X-ray irradiation paves a way for developing the next opportunities of radiotherapy toward efficient tumor prognosis.

Efficacy-shaping nanomedicine by loading Calcium Peroxide into Tumor Microenvironment-responsive Nanoparticles for the Antitumor Therapy of Prostate Cancer

“…Lysosomes are regarded as the terminals of endocytosis, in which most of the internalized macromolecules are degraded by a variety of enzymes and reductants under the environment with a pH value of about 5.0 40 - 42 . To examine the cellular uptake and intracellular distribution of these as-prepared nanocomposites, the chemical cross-link of CaO 2 @HMSNs-PAA and FITC was performed to construct CaO 2 @HMSNs-PAA-FITC, which emitted green fluorescence upon excitation with a laser at 494 nm 41 , 48 . After PC-3 cells were incubated with CaO 2 @HMSNs-PAA-FITC for 0.5 h, 1 h and 3 h, the lysosomes were labeled by LysoTracker Red, which is lysosome-specific and exhibits red fluorescence when excited by a laser at 577 nm.…”

“…For application in control experiments, CaO 2 -loaded HMSNs (CaO 2 @HMSNs) and PAA-coated HMSNs-NH 2 (HMSNs-PAA) were synthesized by a similar process. FITC-labeled CaO 2 @HMSNs-PAA (CaO 2 @HMSNs-PAA-FITC) used in the cellular uptake assay were prepared as follows 48 : 10 mg of FITC reacted with 24 μL of APTES in 4 mL of methanol at room temperature for 24 h in the dark to form FITC-APTES. Next, 50 mg of CaO 2 @HMSNs-PAA was dispersed into the above FITC-APTES solution and the stirring continued under the same conditions for 12 h. After centrifugation (12 000 rpm), CaO 2 @HMSNs-PAA-FITC was rinsed with methanol and lyophilized in the dark.…”

“…The amount of CaO 2 in the supernatant ( m s ) was determined according to the volume of supernatants and the concentration of Ca measured by ICP-MS. The CaO 2 loading capacity was calculated based on the following formula 36 , 48 : CaO 2 loading capacity (%, w/w) = the mass of CaO 2 loaded in CaO 2 @HMSNs-PAA / the mass of CaO 2 @HMSNs-PAA × 100% = ( m 0 - m s ) / m CHP × 100%. The CaO 2 loading capacity of CaO 2 @HMSNs was evaluated with a similar procedure.…”

“…The exploration of CaO 2 release profiles was similar to the calculation of the CaO 2 loading capacity. First, accurately weighted CaO 2 @HMSNs and CaO 2 @HMSNs-PAA were dispersed in a certain volume of PBS with different pH values of 7.4, 6.5, and 5.0, which were used to simulate the circumstances of normal tissues, TME and lysosomes 48 , 50 , and stirred at room temperature. Then, the concentration of Ca in the suspension was detected by ICP-MS at a given time interval, which lasted for 2 h. Finally, the release curves were fitted based on a series of obtained concentrations of CaO 2 to describe the release procedure 36 , 48 .…”

“…Afterwards, the above working solution was discarded. Then, the Trypan blue (Yeasen)/PBS solution (2 mg/mL, 0.5 mL/well) was introduced to quench the intracellular fluorescence at 37 °C for 2 min in the dark 48 . Subsequently, the cells were washed with PBS and methanol, respectively, and the buffer solution included in the above DAPI detection kit was added to the wells.…”