Spectroscopic and photostability study of water-soluble hypericin encapsulated with polyvinylpyrrolidone.

Hypericin has gained great attention as a powerful photosensitizing and fluorescent agent for photodynamic therapy (PDT) and fluorescence diagnosis (FD) of cancer. However, native hypericin is hydrophobic and nearly insoluble in aqueous media which hinders its photobiological activity. Herein, we demonstrate the encapsulation of hypericin and polyvinylpyrrolidone (hypericin@PVP) as an attractive class of water-soluble formula of hypericin with improved absorption and emission characteristics in water. The absorption and fluorescence properties of the water-soluble hypericin@PVP were studied at room temperature. Also, the photostability of the prepared hypericin@PVP was studied under visible light irradiation. The absorbance and emission measurements confirm the association and binding of hypericin and PVP with a binding constant (Kb) of 1.2 × 105 M-1. The interaction between hypericin and PVP in water could lead to the dissociation of aggregated hypericin into their monomeric state which is crucial for effective photobiological implementation in PDT and FD. Upon encapsulation with PVP, hypericin showed a significant increase in the fluorescence properties with an enhanced emission intensity of 300% at a PVP concentration of 1 × 10-4 M. Moreover, water-soluble hypericin@PVP demonstrated high photostability under visible light irradiation with an irradiance of 15 mW/cm2 and exposure time up to 150 min. This enhancement in the absorption, emission, and photostability of hypericin in water is related to the effects of encapsulation with PVP and the unique spectroscopic properties of the formulated hypericin@PVP.

The impact of paracentesis flow rate in patients with liver cirrhosis on the development of paracentesis induced circulatory dysfunction.

BACKGROUND/AIMS: Ascites is a dreadful complication of liver cirrhosis associated with short survival. Large volume paracentesis (LVP) is used to treat tense or refractory ascites. Paracentesis induced circulatory dysfunction (PICD) develops if no plasma expanders are given with ominous complications. To study the effect of ascites flow rate on PICD development. METHODS: Sixty patients with cirrhosis and tense ascites underwent LVP of 8 L were randomized into 3 equal groups of different flow rate extraction; group I (80 mL/minute), group II (180 mL/minute) and group III (270 mL/minute). Plasma renin activity (PRA) was measured baseline and on day six. PICD was defined as increase in PRA >50% of the pretreatment value. RESULTS: In group I through 3; the mean age was (52.5±9.4 vs. 56.4±8.5 vs. 55.8±7.1 years; P>0.05), mean arterial pressure (81.4±5.6 vs. 81.5±7 vs. 79.5±7.2 mmHg; P>0.05), MELD (17.6±4.1 vs. 15.8±4.1 vs. 14.7±4.5). Baseline PRA was comparable (1,366.0±1244.9 vs. 1,151.3±1,444.8 vs. 951.9±1,088 pg/mL; P>0.05). There was no statistically significant (P>0.05) flow mediated changes (Δ) of creatinine (0.23±0.27 vs. 0.38±0.33 vs. 0.26±0.18 mg/dL), MELD (1.25±5.72 vs. 1.70±2.18 vs. 1.45±2.21) or PRA (450.93±614.10 vs. 394.61±954.64 vs. 629.51±1,116.46 pg/mL). PICD was detected in a similar frequency in the three groups (P>0.05). On univariate logistic analysis only female sex was a fairly significant PICD predictor (Wald 3.85, odds ratio 3.14; P=0.05). CONCLUSIONS: The ascites flow rate does not correlate with PICD development.

Subcellular toxicity of gold nanoparticles irradiated with 532 nm pulsed laser.

OBJECTIVE: Prior to plasmonic photothermal therapy, involving heating of gold nanoparticles (GNPs) by laser, we explored some subcellular events that may threaten the viability of rat kidney cells (RKCs) incubated with GNPs irradiated with pulsed laser. BACKGROUND DATA: We have previously shown a decrease in the viability of RKCs, on incubation with GNPs irradiated with pulsed laser. This decrease in viability was concomitant to a reduction in GNP diameter size, and reflected the occurrence of subcellular toxic events. METHODS: After incubation of RKCs with GNPs irradiated with 532 nm pulsed laser (50 mJ/pulse energy, 5 ns duration, and 10 Hz repetition rate for 1, 3, and 5 min), we studied the cell membrane integrity, the induction of apoptosis, and the occurrence of oxidative stress. We reported the changes induced on RKCs by GNPs irradiated with pulsed laser and those induced on the same cells and after the same time intervals by unirradiated GNPs; both were related to a negative control. RESULTS: The decrease in viability of RKCs on incubation with GNPs irradiated with pulsed laser was shown to be mostly secondary to a cell membrane disruption, most probably related to the reduction in GNP diameter sizes. The oxidative stress exerted by smaller GNPs on RKCs, as well as the induction of apoptosis, seem to be tolerated by the RKCs. CONCLUSIONS: Irradiation of GNPs with pulsed laser, to elicit a plasmonic photothermal effect, reduces the GNPs' diameter. The smaller-sized GNPs may lead to lethal cell membrane disruption in healthy RKCs.

Laser-induced modifications of gold nanoparticles and their cytotoxic effect.

As nanotechnology continues to develop, an assessment of nanoparticles' toxicity becomes very crucial for biomedical applications. The current study examines the deleterious effects of pre-irradiated gold nanoparticles (GNPs) solutions on primary rat kidney cells (PRKCs). Spectroscopic and transmission electron microscopic studies demonstrated that exposure of 15 nm GNPs in size to pulsed laser caused a reduction both in optical density and mean particle diameter. GNPs showed an aggregation when added to the cell culture medium (DMEM). This aggregation was markedly decreased upon adding serum to the medium. Under our experimental conditions, trypan blue and MTT assays revealed no significant changes in cell viability when PRKCs were incubated with non-irradiated GNPs over a period of 72 h and up to 4 nM GNPs concentration. On the contrary, when cells were incubated with irradiated GNPs a significant reduction in PRKCs viability was revealed.