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Quercetin is a naturally occurring phytochemical with good bioactivity, which mainly exists in the form of glycoside in vegetables, fruits, tea, and wine and exhibits beneficial health effects. Quercetin is a dietary polyphenol that exerts the protective effects through diet or use as a food supplement. Compared with chemical agents, quercetin is widely available and safe. Quercetin has been extensively studied for its anti-diabetic, anti-hypertensive, anti-Alzheimer's disease, anti-arthritic, anti-influenza virus, anti-microbial infection, anti-aging, autophagy-regulating, and cardiovascular protective effects. Studies on its activities against different can-cer cell lines have also been reported recently. However, the poor water solubility, rapid in vivo metabolism, and short half-life of quercetin have led to its low bioavailability, thus limiting its application in the field of medicine. Quercetin nanoparticles and nanoparticle drug delivery system have been effectively utilized for enhancing its bioavailability. This paper reviewed the therapeutic potential of quercetin from both preclinical and clinical aspects and proposed solutions to improve its bioavailability, so as to provide a reference for the therapeutic application of natural compounds in the field of medicine.

Puerarin (PUE) is a good candidate for treating stroke, but its low concentration in brain after administration limits its curative efficacy. The aim of the present work was to design and characterize PUE loaded poly(butylcyanoacrylate) nanoparticles (PBCN) coated with polysorbate 80 (Ps 80), and to evaluate the effect of PBCN on the permeability of PUE across the blood-brain barrier (BBB) and the effect of PUE loaded PBCN on the cerebral ischemia/reperfusion injury. PUE loaded PBCN were successfully prepared by anionic polymerization method with the mean particle size of 201.2 nm and the zeta potential of -7.72 mV. The in vitro release behavior of PUE from the nanoparticles showed a biphasic profile manner with an initial burst release followed by a sustained release. The results of pharmacokinetic and biodistribution to brain performed in mice after intravenous administration showed that the drug concentrations in blood and brain for PUE loaded PBCN were both greater than these for the free drug. Moreover, compared with free drug, the vein injection of PUE loaded PBCN exerted the better neuroprotective effect in rats with focal cerebral ischemic injury via significantly decreasing neurological deficit scores, increasing body weight, lowing brain water content, and reducing the infarct volume. The results indicated that this preparation may reduce the total dose required for the stroke therapy with concurrent reduction in dose related toxicity. All these findings suggest that PBCN could enhance the transport of PUE to brain and have a potential as a neuroprotective agent in the focal cerebral ischemic injury.

Objective: To prepare curcumin-loaded lipid cubic liquid crystalline nanoparticles and evaluate its physiochemical properties., Methods: The nanoparticles were prepared using hot and high-pressure homogenization. The prescription and preparation process were optimized by uniform design with drug loading and entrapment efficiency as indexes., Results: The nanoparticles were spherical under transmission electron microscope (TEM) with average particle size of 176.1 nm, zeta potential of -25.19 mV, average drug loading of (1.5 +/- 0.2)% and entrapment efficiency of (95 +/- 1.8)%. The release equation: In (1-Q) = -0.0251t-0.0075. The cumulative release percentage was 60% at 36 h in vitro., Conclusion: The obtained curcumin-loaded lipid cubic liquid crystalline nanoparticles shows high entrapment efficiency and good sustain release property.

Objective: To prepare Apigemin-loaded nanostructured lipid carriers (Api-NLCs) and evaluate their characteristics., Methods: Api-NLCs were prepared by the method of emulsion evaporation-solidification at low temperature. The physicochemical properties such as morphology, size distribution, zeta potential, entrapment efficiency, drug loading and drug release in vitro were evaluated., Results: The obtained nanoparticles were spherical under transmission electron microscope. The mean diameter was 212.1 nm, the zeta potential was - 14.65 mV, the mean entrapment efficiency was 82.4% and the mean drug loading was 0.97%. The total drug release was 30% in 2 hours followed by a slow and sustained release in vitro., Conclusion: The optimal Api-NLCs show stable characteristics and broad prospects for application.

Objective: To prepare curcumin polybutylcyanoacrylate nanoparticles (Cur-PBCNs) and evaluate its characteristics., Methods: Cur-PBCNs were prepared by emulsion polymerization, and the formulation was optimized by L16 (4(3)) orthogonal design test with entrapment efficiency and drug loading as indices. In addition, its characteristics were investigated., Results: The nanoparticles were spherical in appearance under transmission electron microscope (TEM). The mean diameter of the nanoparticles was 93.8 nm, the mean entrapment efficiency was (50.4 +/- 2.2)%, the mean drug-loading was (33.5 +/- 0.9)% and the Zeta potential was -6.81 mV. The total drug release was 34.74% in 2 hours followed by a sustained release in vitro for Cur-PBCNs, and the in vitro release profile of the nanoparticles was fit for two phases kinetics equation: 100 - Q = 4.5235e(-0.1724t) + 4.1641e(-0.0114t)., Conclusion: The optimal Cur-PBCNs show good characteristics and sustained release character in vitro.

Objective: To prepare and characterize the solid lipid nanoparticles containing norcantharidin., Methods: Entrapment efficiency was studied to choose the best method of preparing norcantharidin solid lipid nanoparticles. The physico-chemical properties of norcantharidin solid lipid nanoparticles were investigated., Results: The entrapment efficiency of norcantharidin in solid lipid nanoparticles was 54.6%, the average particle diameter was 190 nm, and it was stable at 4 degrees C for 3 months., Conclusion: Solid lipid nanoparticles of norcantharidin prepared has high entrapment efficiency and good stability.

Platinum (Pt) is the most effective bench‐marked catalyst for producing renewable and clean hydrogen energy by electrochemical water splitting. There is demand for high HER catalytic activity to achieve efficient utilization and minimize the loading of Pt in catalysts. In this work, we significantly boost the HER mass activity of Pt nanoparticles in Ptx/Co to 8.3 times higher than that of commercial Pt/C by using Co/NC heterojunctions as a heterogeneous version of electron donors. The highly coupled interfaces between Co/NC and Pt metal enrich the electron density of Pt nanoparticles to facilitate the adsorption of H+, the dissociation of Pt−H bonds and H2 release, giving the lowest HER overpotential of 6.9 mV vs. RHE at 10 mA cm−2 in acid among reported HER electrocatalysts. Given the easy scale‐up synthesis due to the stabilization of ultrafine Pt nanoparticles by Co/NC solid ligands, Ptx/Co can even be a promising substitute for commercial Pt/C for practical applications. [ABSTRACT FROM AUTHOR]