Evaluation of hypericin-loaded solid lipid nanoparticles: Physicochemical properties, photostability and phototoxicity

Abstract

Hypericin (HYP), a natural photosensitizer, has powerful photo-oxidizing ability, tumor-seeking characteristics, and minimal dark toxicity; nevertheless, it has proven high lipid solubility compared to its sparingly water soluble nature. Therefore, its formulation into solid lipid nanoparticles (SLNs) has attracted increasing attention as a potential drug-delivery carrier. Two HYP-loaded SLNs formulations were prepared utilizing microemulsion-based technique. Thereafter, the physicochemical properties of the formulations were investigated and evaluated. HYP-loaded SLNs showed spherical shape with mean particle size ranging from 200-300 nm for both formulations (FA and FB). The encapsulation efficiencies reached above 80% and FA showed significant higher encapsulation than FB (P<0.05), also, the thermal analysis using differential scanning calorimetry (DSC) indicated good compatibility between hypericin and lipids forming the cores in both formulations. Spectroscopic measurements of the photostability study showed that hypericin encapsulation into SLNs improved its photostability, compared to free HYP in 0.1% ethanolic solution. However, photocytotoxicity studies on HepG2 cells revealed an evident inhibition of the photodynamic efficacy of HYP-loaded SLNs, compared to free HYP. In conclusion, although the elevated entrapment efficiency of HYP into SLNs increased its photostability, it decreased its phototoxicity which might be due to the quenching deactivation of HYP molecules resulting from SLN compactness and thickness structure.

Facile fabrication of hypericin-entrapped glyconanoparticles for targeted photodynamic therapy

“…[18][19][20] A promising strategy to overcome this problem is to associate Hy with a nanocarrier that is biocompatible and dispersible in an aqueous physiologic environment. 21 Solid lipid nanoparticles (SLNs) are the most studied Hy nanocarriers; 20,22,23 they show good tolerability and biocompatibility, can protect the incorporated drug from chemical-and photodegradation, and the exposed polyethylene glycol (PEG) units on the surface of SLNs afford good aqueous dispersibility and long circulation potential. The Hy-loaded SLNs exhibit remarkable dark cytotoxicity and PDT effect on cancer cells.…”

Stimuli‐Responsive Biomaterials for Vaccines and Immunotherapeutic Applications

“…[ 50 ] Other formulations have been developed such as solid lipid NPs loaded with hypericin, a natural photosensitizer. [ 51 ]…”

Application of nanomedicine for crossing the blood–brain barrier: Theranostic opportunities in multiple sclerosis

“…Among the various techniques used for production of SLN, highpressure homogenization at high temperatures (Silva et al 2011) and microemulsion (Youssef et al 2012) are the most applied methods used for SLN generation. These NP have several features such as high stability and tolerability, gradual drug release, specific targeting and protection of labile drugs from degradation.…”