PH-responsive Mesoporous Silica Nanoparticles For Controlled Release Of Anti-arthritis Drug

Background and purpose: Osteoarthritis(OA)is the most common type of arthritis and has been considered to be a joint disease affecting the health and quality of life of billions of people worldwide.Plant-derived natural products have attracted much attention in the treatment of inflammatory diseases due to their low toxicity and fewer adverse reactions.Studies have shown that andrographolide(AG)can relieve symptoms and reduce immune marker levels in patients with rheumatoid arthritis.However,due to the low water solubility of AG,it is not conducive to the body’s absorption,resulting in oral or articular injection can not make it the best utilization rate.In recent years,research on drug delivery systems(DDSs)for intra-articular injection has attracted much attention.The combination of inorganic nanoparticles with good biocompatibility and hydrophobic drugs is one of the strategies of DDSs.Mesoporous silica nanoparticles(MSNs)have extremely high specific surface area,pore volume and excellent surface modification properties,and have been widely studied in the field of acting as drug carriers.However,due to the low drug release rate of most MSNs drug carriers,the actual clinical application has also been greatly limited.Studies have shown that in patients with severe arthritis,the p H of the joint fluid can be as low as about 6.0.Therefore,this study is based on the fact that p Hresponsive DDSs can reduce unnecessary drug release when the degree of OA is low,thereby prolonging the residence time of the drug in the joint to improve the efficacy of the drug,and explore the effect of p H-responsive DDSs on OA.Methods:(1)For material synthesis and characterization,based on the modified St?ber method,we prepared a p H-responsive MSNs nano drug carrier(MSNs-PAA).Use transmission electron microscope(TEM),Malvern particle size analyzer,Zeta potential analysis,Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and high-performance liquid phase High performance liquid chromatography(HPLC)and so on carried out the material characterization and detection of the nano drug-carrying system.(2)In vitro cytology: We used 2% type II collagenase to treat the knee joint cartilage tissue of 2-week-old SD baby rats,and extracted primary articular chondrocytes for culture,and passed it to the third generation for in vitro experimental research.We first use the CCK 8 method to evaluate the biological toxicity of AG,MSNs,MSNs-PAA and AG@MSNs-PAA to chondrocytes respectively.Then,after 10 ng/m L IL-1β was applied to chondrocytes for 2 h,8μM AG,8 μM AG@MSNs,and 8 μM AG@MSNs-PAA were applied to OA cells for 24 h,respectively,and a blank control group was set up.(Control group)and positive group(IL-1β group).Finally,in vitro cytology tests such as live cell staining,Safranin O staining,and immunofluorescence staining were used to evaluate the efficacy.(3)Animal in vivo experiment part: We performed anterior cruciate ligament transaction(ACLT)and medial meniscectomy(MM)on SD rats to establish rat OA model.In the fourth week after the operation,drugs were injected into the joint cavity of SD rats for intervention treatment,twice a week,0.2 ml each time,for four consecutive weeks.Subsequent joint macroscopic observation scores,histological histological staining(HE staining,safranine O fast green,immunohistochemical staining)and scoring,etc.,to evaluate the efficacy.Results:(1)Material synthesis and characterization: TEM results show that MSNsPAA is a sphere of uniform size;Malvern particle size analyzer shows that its average diameter is about 120 nm;Zeta potential analysis shows that after connecting PAA,MSNs-PAA nanometers The surface charge of the particles decreased from-20.93 ± 2.35 m V of MSNs to-28.12 ± 2.35 m V of MSNs-PAA;FTIR and XRD analysis confirmed that PAA can be successfully connected to the surface of MSNs by our method to obtain MSNs-PAA;HPLC Analysis shows that the p H-responsive nanoparticles have a high drug loading efficiency(22.38 ±0.71%),and also show a high drug sustained-release efficiency in a low p H environment.(2)Evaluation of the therapeutic effect of AG@MSNs-PAA on chondrocyte OA in vitro: when the concentration of AG@MSNs-PAA is 8 μM,it shows that it has the strongest protective effect on injured chondrocytes.Compared with the IL-1β group,the PCR results in the AG group,MSNs-PAA group,and AG@MSNs-PAA group showed that the levels of Col2α1 and Acan were significantly increased,while IL-1β-mediated inflammatory factors(MMP 3,MMP 13,IL 6,Nos 2)secretion was significantly inhibited(p <0.05).Fluorescence microscopy revealed that MMP 13 expression was the lowest in chondrocytes under the intervention of AG@MSNs-PAA.This result was consistent with the m RNA expression level of MMP 13 detected by PCR.(3)Evaluation of the therapeutic effect of AG@MSNs-PAA on OA rats: The AG@MSNs-PAA group showed a better treatment effect.In addition,the expression of MMP 1 in the articular cartilage of SD rats in different groups was detected by immunohistochemical staining.After staining with AG intervention,the positive expression rate of MMP 1 in the AG@MSNs-PAA group was the lowest in the experimental group.,Indicating that it has the best treatment effect on OA.Conclusion: This study suggests that the AG@MSNs-PAA nano drug-loaded system shows good effects against pathological changes of osteoarthritis,can obviously protect the normal function and structure of cartilage tissue,and reduce the expression of chondrocyte inflammatory factors.There is a potential effective way to treat OA.