Researches On The Micro/Nano-drug Delivery Systems Of Quercetin Fabricated Using Electrohydrodynamic Atomization Methods

Quercetin is an important flavonoid found in many plants and foods with extensive physiological functions, such as antimicrobial, antiviral, antitussive, expectorant, antioxidant, antidiabetic. Growing evidences suggest that quercetin may involve in the suppression of many tumor-related processes including oxidative stress, apoptosis, proliferation and metastasis. Reportedly, quercetin protects normal, non-transformed cells from various stresses but exerts inhibitory proliferation and pro-apoptatic effects on a variety of cancer cells in vitro such as human hepatoceIlular, breast, gastric, colon and prostate cancer cell lines. Hence, quercetin is considered as an important candidate of natural chemo-preventer. However, the poor solubility of quercetin in water and bioavailability present a major problem for its administration. Accordingly, it is necessary to exploite the new drug delivery systems (FDDS) of querectin to meet different treatment needs.Electrohydrodynamic atomization processes (EHDA, mainly including electrospinning and electrospray) have been successfully used to generate drug-loaded nano/micro fibers or particles in biomedical field as a powerful tool for its special functions. Drug-loaded nanofiers or microparticles with improved dissolution and different release profiles can be easily prepared by modulation the procession parameters and the polymer max. In this work, quercetin-loaded nanofibers/microparticles have been fabricated using electrospinning or electrospraying, providing sustained, adjustable biphasic and fast drug release profiles respectively in vitro. Further more, the antioxidant activity and anti-tumor activity in A549 cells of the fast-dissolving quercetin-loaded microparticles have been evaluated in vitro.High quality drug sustained-release quercetin-loaded nanofibers have been prepared using single fluid electrospinning process. FESEM observations showed that the nanofibers were of liner structure with smooth surface and few beads-on-a-string morphological anomalies. XRD and DSC results suggested that quercetin in the nanofibers was completely amorphous. ATR-FTIR spectra verified that hydrogen bonding occurred within the composite nanofibers, yielding a high degree of compatibility between the nano fiber components and a homogeneous nano-composite of quercetin and EC consequently. Furthermore, the electrospinning parameters were optimized and the effect of a spinneret with a Teflon nozzle on the procession and the product quality was also evaluated. Compared with the traditional stainless spinner, a Teflon-spinneret provided a better performance for implementing electrospinning in the following aspects: (1) keeping more electrical energy on the working fluids for an efficacious process; (2) exerting less negative effect on the fluid to draw it back to the tube; and (3) making less possibility of clogging. The resulted nanofibers from the spinneret with a Teflon nozzle exhibited higher quality than those from the traditional spinneret in those:(1) smaller diameter and narrower distribution (520±70 nm); and (2) better sustained-release profiles of quercetin as demonstrated by the in vitro dissolution tests.Dual release composite microparticles of quercetin have been generated using single fluid electrospray. The SEM images of the microparticles had a "flat" morphology, like the pancakes, with a diameter distrivution of 1.74±0.37 μm. The combined XRD and light microscopy results clearly demonstrate that quercetin existed in the amorphous form in the electrosprayed multiple-component microparticles. ATR-FTIR spectra indicated that hydrogen bonding occured between the drug molecule and the polymer matrices. The in vitro release profiles showed that microparticles were able to provide a typical dual drug release profile, i.e. an initial fast release of 53.7% contained drug, and later exhausted the remnant quercetin.Tunable biphasic release quercetin-loaded nanofibers have been fabricated using a modified coaxial electrospinning. Three quercetin-loaded nanofibers were obtained with average diameters of 840±110 nm,830 ± 140 nm and 860 ± 120 nm respectively. FESEM images showed that the coaxial quercetin-loaded nanofibers had smooth surfaces and cross-sections without any "beads-on-a-string" morphology or discriminable particles generated by phase separation, suggesting a homogeneous structure in both the shell and core. Meanwhile, a series of optimization experiments were performed to enable electrospinning proceed successfully with a non-electrospinnable core fluid. Finally, the shell and core flow rates were selected of 0.3 and 0.7 mL h-1 respectively. Compared with the traditional stainless spinner, when a Teflon-spinneret was exploited there were a larger deflection angle, a smaller Taylor cone and a shorter straight fluid jet in the electrospinning process, implying that PVC can effectively retard the loss of electrical energy to environment.Fast-dissolving core-shell composite microparticles containing quercetin have been fabricated using a coaxial electrospray. The drug content in the products could be tuned through the flow rate of the core solutions (within an appropriate range) or the drug concentrations therein. Particles were prepared with three different drug loadings of 7.64, 10.71, and 16.67%w/w, and average diameters of 1.69 ± 1.13,1.74 ± 1.02 and 1.85 ± 0.83 μm respectively. SEM and TEM images clearly evidenced the core/shell structure. The components in both the core and the shell existed in an amorphous physical form as a result of favorable interactions between them, as demonstrated by XRD, DSC and ATR-FTIR. The microparticles increased both the dissolution and permeation rates of quercetin, and had permeation rate across sublingual mucosa around 10 times faster than quercetin powders.The antioxidant activity and anti-tumor activity in A549 cells of the nanofibers/microparticles represented by fast-dissolving quercetin-loaded microparticles (QUEM) have been evaluated in vitro. QUEM exhibited more effective scavenging activity than free quercetin powders (QUE) against DPPH·,·OH and O2-·, and more potent inhibitory effects on A549 cell growth with reduced cell viability, more apoptosis and necrosis, a decreased cell migration and inducing G0/G1 phase cell cycle arrest. The increased antitumor activity should be attributed to that the accumulation of quercetin in the A549 cells was higher for the QUEM than QUE. The particles without quercetin showed no cytotoxicity on A549 cells, implying that the QUEM fabricated by EHDA were safe and all the ingredients were nontoxic. Hence, several novel quercetin drug delivery systems have been successfully prepared using electrohydrodynamic atomization processes with improved dissolution, permeation performance and pharmacological activity. Thus the work provides strategies for resolving one of the most difficult problems in pharmaceutics that is the dissolution and absorbance of poorly water soluble drugs. Meanwhile, the study results will have an important value for the preparation of novel nanobiomaterial.