In this study, tetrandrine-loaded cationic solid lipid nanoparticles (TET-CNP) and solid lipid nanoparticles (TET-NP) were prepared by the emulsion evaporation-solidification at low temperature method. The particle size, zeta potential, and entrapment efficiency of TET-CNP and TET-NP were characterized. The results showed that the TET-CNP and TET-NP had average diameters of (15.29 ± 1.34) nm and (18.77 ± 1.23) nm with zeta potentials of (5.11 ± 1.03) mV and (-8.71 ± -1.23) mV and entrapment efficiencies of (94.1 ± 2.37)% and (95.6 ± 2.43)%, respectively. In vitro release studies indicated that the TET-CNP and TET-NP retained the drug entity better than tetrandrine ophthalmic solutions (TET-SOL). In the pharmacokinetics studies, the AUC values of TET-CNP and TET-NP were 1.96-fold and 2.00-fold higher than that of TET-SOL ( p < 0.05); the Cmax values of TET-CNP and TET-NP were 2.45-fold and 2.53-fold higher than that of the TET-SOL (p < 0.05), respectively. Cytotoxicity study showed that TET-CNP and TET-NP had no significant toxicity at low concentrations. Flow cytometry studies and confocal microscopy analysis demonstrated that calcein labeled NP (CA-NP) uptake by SRA 01/04 cells was much higher than those of calcein labeled CNP (CA-CNP) and calcein solution (CA-SOL).

Along with the exuberant development of nanotechnology, a large number of nanoformulations or non materials are successfully applied in the clinics, biomedicine, cosmetics and industry. Despite some unique advantages of nanoformulations, there exist potentially worrying toxic effects, particularly those related to metal and metal-containing nanoparticles (NPs). Although various researches have been conducted to assess the metallic and metal-containing nanoparticles toxic effects, only little is known about the toxicity expressive types and evaluation, reasons and mechanisms, influencing factors and research methods of metal and metal-containing nanotoxicity. Therefore, it is of importance to acquire a better understanding of metal and metal-containing nanoparticles toxicity for medical application. This review presents a summary on the metal and metal-containing nanoparticles toxicity research progress consulting relevant literature.

Abstract. Breviscapine is used in the treatment of ischemic cerebrovascular diseases, but it has a low bioavailability in the brain due to its poor physicochemical properties and the activity of P-glycoprotein efflux pumps located at the blood-brain barrier. In the present study, breviscapine-loaded solid lipid nanoparticles (SLN) coated with polyethylene glycol (PEG) derivatives were formulated and evaluated for their ability to enhance brain bioavailability. The SLNs were either coated with polyethylene glycol (40) (PEG-40) stearate alone (Bre-GBSLN-PS) or a mixture of PEG-40 stearate and 1,2-distearoyl-snglycero-3-phosphoethanolamine-N-PEG2000 (DSPE-PEG 2000 ) (Bre-GBSLN-PS-DSPE) and were characterized both in vitro and in vivo. The mean particle size, polydispersity index, and entrapment efficiency for Bre-GBSLN-PS and Bre-GBSLN-PS-DSPE were 21.60±0.10 and 22.60±0.70 nm, 0.27±0.01 and 0.26 ±0.04, and 46.89±0.73% and 47.62±1.86%, respectively. The brain pharmacokinetic parameters revealed that the brain bioavailability of breviscapine from the Bre-GBSLN-PS and Bre-GBSLN-PS-DSPE was significantly enhanced (p<0.01) with the area under concentration-time curve (AUC) of 1.59±0.39 and 1.42±0.58 μg h/mL of breviscapine, respectively, in comparison to 0.11±0.02 μg h/mL from the commercial breviscapine injection. The ratios of the brain AUC for scutellarin in comparison with the plasma scutellarin AUC for commercial breviscapine injection, Bre-GBSLN-PS, and Bre-GBSLN-PS-DSPE were 0.66%, 2.82%, and 4.51%, respectively. These results showed that though both SLN formulations increased brain uptake of breviscapine, Bre-GBSLN-PS-DSPE which was coated with a binary combination of PEG-40 stearate and DSPE-PEG 2000 had a better brain bioavailability than Bre-GBSLN-PS. Thus, the coating of SLNs with the appropriate PEG derivative combination could improve brain bioavailability of breviscapine and can be a promising tool for brain drug delivery.

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