Karina Paese

Poly(ϵ-caprolactone) microcapsules and nanocapsules in drug delivery

Introduction: Poly(ϵ-caprolactone) (PCL), a biodegradable and biocompatible polymer, is useful to encapsulate a wide range of drugs making it an interesting material for the preparation of carriers with potential applications in therapeutics. Areas covered: The design and development of those carriers to modulate drug release, to improve the drug stability or apparent solubility in aqueous media, as well as to target tissues and organs are discussed. Expert opinion: Microencapsulation is a well-established process in pharmaceutical industry to protect drugs from chemical degradation and to control drug release. In this context, PCL is a useful polymer to prepare microcapsules. Nanoencapsulation, a more recent approach, offers new possibilities in drug delivery. PCL can be used as polymer to prepare different types of nanocapsules presenting diverse flexibility according to the chemical nature of the core. Those nanocapsules are capable of controlling drug release and improving photochemical stability. In addition, they can modulate cutaneous drug penetration/permeation and act as physical sunscreen due to their capability of light scattering. Considering the pharmaceutical point of view, PCL nanocapsules are versatile formulations, once they can be used in the liquid form, as well as incorporated into semi-solid or solid dosage forms.

Characterisation and stability evaluation of bixin nanocapsules

The aim of this study was to produce bixin nanocapsules by the interfacial deposition of preformed poly-ε-caprolactone (PCL). PCL (250 mg), capric/caprylic triglyceride (400 μL), sorbitan monostearate (95 mg) and bixin were dissolved in a mixture of acetone (60 mL) and ethanol (7.5 mL) under stirring (40 °C). This organic solution was added to the aqueous solution (130 mL) containing Tween 80 (195 mg). The size distributions in the formulations with bixin concentration from 11 to 100 μg/mL were evaluated periodically during 3 weeks of storage at ambient temperature. The optimal formulation (bixin concentration of 16.92±0.16 μg/mL) was characterised in terms of particle size distribution, zeta potential, bixin content and encapsulation efficiency, and showed a volume-weighted mean diameter (D4,3) of 195±27 nm, around 100% of encapsulation efficiency and the nanocapsules were considered physically stable during 119 days of storage at ambient temperature.

Estabilização do ácido lipoico via encapsulação em nanocápsulas poliméricas planejadas para aplicação cutânea

This work reports the development of polymeric nanocapsules containing lipoic acid prepared by interfacial deposition of poli(e-caprolactona). The suspensions showed acid pH and encapsulation efficiencies from 77 to 90%. Zeta potential values were from -7.42 to -5.43 mV and particle sizes were lower than 340 nm with polidispersion lower than 0.3. The stability of nanocapsules within 28 days was evaluated in terms of pH, lipoic acid content, diameter, size distribution, zeta potential and measurements of relative light backscattering. The stability of formulations containing free lipoic acid was also evaluated. Nanoencapsulation drastically improved the physico-chemical stability of lipoic acid.

Innovative Sunscreen Formulation Based on Benzophenone-3-Loaded Chitosan-Coated Polymeric Nanocapsules

Aim: To evaluate the effect of cationic coating of polymeric nanocapsules in sunscreen formulations on the in vitro skin penetration of benzophenone-3. Methods: Benzophenone-3-loaded nanocapsules were prepared by the interfacial deposition of poly(Ε-caprolactone) and coated by using a chitosan solution. The nanoparticles were characterized and incorporated in hydrogels. The presence of nanoparticles in hydroxyethyl cellulose gels was observed by transmission electron microscopy and photon correlation spectroscopy. Penetration studies were carried out using Franz cells with porcine skin membranes. Results: Benzophenone-3-loaded chitosan-coated nanocapsules presented a mean size of 202 ± 7 nm and positive zeta potential (+21 ± 1 mV), while these values for the uncoated nanocapsules were 175 ± 1 nm and –8 ± 1 mV. Penetration profiles showed that a higher amount of benzophenone-3 remained at the skin surface and a lower amount was found in the receptor compartment after the application of the formulation containing chitosan-coated nanocapsules compared to a formulation containing its free form. Conclusions: Hydrogel containing benzophenone-3 chitosan-coated nanocapsules represents an innovative formulation to overcome limitations of sunscreen daily use.

Reapplication improves the amount of sunscreen, not its regularity, under real life conditions.

The sun protection factor (SPF) of sunscreens is determined using samples applied with a thickness of 2 mg cm−2. Sunscreen users, however, typically apply sunscreen nonuniformly and in smaller amounts. The objective of our study was to verify whether sunscreen reapplication increases the amount and regularity of the product on the skin. Volunteers were asked to apply an SPF 6 sunscreen on their forearms and reapply it 30 min later on one forearm. Tape‐strips were used to collect five samples from two different sites on each forearm. The concentration of benzophenone‐3 in the samples was measured and the total amount of sunscreen was estimated using high‐performance liquid chromatography. The median amount of sunscreen film was 0.43 mg cm−2 (0.17–1.07) after one application and 0.95 mg cm−2 (0.18–1.91) after two applications (P = 0.002). No significant difference was found in the film uniformity. Though sunscreen reapplication increases the amount of product on the skin, levels are still lower than the recommended amount, confirming that the protection level is less than the product‐stated SPF. Our results are the first in the literature to support the recommendation for reapplying sunscreens. Based on our results, we recommend that sunscreens be labeled using qualitative measures.

PEGylated Carbon Nanotubes Impair Retrieval of Contextual Fear Memory and Alter Oxidative Stress Parameters in the Rat Hippocampus

Carbon nanotubes (CNT) are promising materials for biomedical applications, especially in the field of neuroscience; therefore, it is essential to evaluate the neurotoxicity of these nanomaterials. The present work assessed the effects of single-walled CNT functionalized with polyethylene glycol (SWCNT-PEG) on the consolidation and retrieval of contextual fear memory in rats and on oxidative stress parameters in the hippocampus. SWCNT-PEG were dispersed in water at concentrations of 0.5, 1.0, and 2.1 mg/mL and infused into the rat hippocampus. The infusion was completed immediately after training and 30 min before testing of a contextual fear conditioning task, resulting in exposure times of 24 h and 30 min, respectively. The results showed that a short exposure to SWCNT-PEG impaired fear memory retrieval and caused lipid peroxidation in the hippocampus. This response was transient and overcome by the mobilization of antioxidant defenses at 24 h. These effects occurred at low and intermediate but not high concentration of SWCNT-PEG, suggesting that the observed biological response may be related to the concentration-dependent increase in particle size in SWCNT-PEG dispersions.

Protective effects of melatonin-loaded lipid-core nanocapsules on paraquat-induced cytotoxicity and genotoxicity in a pulmonary cell line

Many acute poisonings lack effective and specific antidotes. Due to both intentional and accidental exposures, paraquat (PQ) causes thousands of deaths annually, especially by pulmonary fibrosis. Melatonin (Mel), when incorporated into lipid-core nanocapsules (Mel-LNC), has enhanced antioxidant properties. The effects of such a formulation have not yet been studied with respect to mitigation of PQ- induced cytotoxicity and DNA damage. Here, we have tested whether Mel-LNC can ameliorate PQ-induced toxicity in the A549 alveolar epithelial cell line. Physicochemical characterization of the formulations was performed. Cellular uptake was measured using nanocapsules marked with rhodamine B. Cell viability was determined by the MTT assay and DNA damage was assessed by the comet assay. The enzyme-modified comet assay with endonuclease III (Endo III) and formamidopyrimidine glycosylase (FPG) were used to investigate oxidative DNA damage. Incubation with culture medium for 24h did not alter the granulometric profile of Mel-LNC formulations. Following treatment (3 and 24h), red fluorescence was detected around the cell nucleus, indicating internalization of the formulation. Melatonin solution (Mel), Mel-LNC, and LNC did not have significant effects on cell viability or DNA damage. Pre-treatment with Mel-LNC enhanced cell viability and showed a remarkable reduction in % DNA in tail compared to the PQ group; this was not observed in cells pre-treated with Mel. PQ induces oxidative DNA damage detected with the enzyme-modified comet assay. Mel-LNC reduced this damage more effectively than did Mel. In summary, Mel-LNC is better than Mel at protecting A549 cells from the cytotoxic and genotoxic effects of PQ.

Pharmacokinetic Investigation of Quetiapine Transport across Blood–Brain Barrier Mediated by Lipid Core Nanocapsules Using Brain Microdialysis in Rats

Lipid-core nanocapsules (LCNs) have been proposed as drug carriers to improve brain delivery by modulating drug pharmacokinetics (PK). However, it is not clear whether the LCNs carry the drug through the blood-brain barrier or increase free drug penetration due to changes in the barrier permeability. Quetiapine (QTP) penetration to the brain is mediated by influx transporters and therefore might be reduced by drug transporters inhibitiors as probenecid. The goal of this work was to investigate the role of type-III LCNs on brain penetration of QTP using microdialysis in the presence probenecid. QTP-loaded LCN (QLNC) was successfully obtained with a small particle size (143 ± 6 nm), low polydispersity index (PI < 0.1), and high encapsulation efficiency (95.4 ± 1.82%.). Total and free drug concentration in plasma and free drug concentration in brain were analyzed following i.v. bolus dosing of nonencapsulated drug (FQ) and QLNC formulations alone and in association with probenecid to male Wistar rats. QTP free plasma fraction right after administration of QLNC was smaller than the fraction observed after FQ dosing; however, it increased over time until similar free drug levels were attained, suggesting that type-III LNCs produce a short in vivo sustained release of the drug. The inhibition of influx transporters by PB led to a reduction of free QTP brain penetration, as observed by the reduction of penetration factor from 1.55 ± 0.17 to a value closer to unit (0.94 ± 0.15). However, when the drug was nanoencapsulated, the inhibition of influx transporters had no effect on the brain penetration factor (0.88 ± 0.21 to 0.92 ± 0.13) probably because QTP is loaded into LNC and not available to interact with transporters. Taken together, these results suggest that LNC type-III carried QTP in the bloodstream and delivered the drug to the brain.

Pre-clinical investigation of the modulation of quetiapine plasma pharmacokinetics and tissues biodistribution by lipid-core nanocapsules.

This study aims to investigate the changes in plasma pharmacokinetics and liver and brain distribution of quetiapine (QTP) due to its encapsulation into a polymeric nanocarrier. For this reason a bioanalytical method was developed and validated in order to quantify QTP in plasma, liver and brain tissue samples. The method was linear over the concentration range of 0.025-3.0μg.mL (r(2)>0.98), accurate, precise (R.S.D<±15%) and the recoveries, stability and validation parameters are within the acceptable limits determined by international guidelines. Plasma pharmacokinetics, cerebral and hepatic distribution of the drug were carried out after intravenous administration of 5mgkg(-1) of nanoencapsulated (QLNC) or free-QTP to male Wistar rats. Increasing half-life was observed for QLNC in relation to free-QTP due to o significant decrease in total clearance. QTP volume of distribution was not altered due to encapsulation. An increase in QTP liver exposure was observed after nanoencapsulation probably due to a reduction in drug metabolization process.

Nanoencapsulation of chia seed oil with chia mucilage (Salvia hispanica L.) as wall material: Characterization and stability evaluation

In this study, chia seed oil was nanoencapsulated utilizing chia seed mucilage (CSM) as wall material. The viscosity, encapsulation efficiency, loading capacity, transmission electron microscopy, FT-IR spectroscopy and thermal properties of chia seed oil nanoparticles (CSO-NP) were performed after preparation. Particle size, zeta potential, span value, and pH of CSO-NP and oxidation stability of nanoencapsulated and unencapsulated oil were evaluated during 28days of storage at accelerated conditions (40°C). The CSO-NP showed spherical shape, an average size of 205±4.24nm and zeta potential of -11.58±1.87mV. The encapsulation efficiency (82.8%), loading capacity (35.38%) and FT-IR spectroscopy demonstrated the interaction between oil and mucilage. Furthermore, CSO-NP were thermally stable at temperatures up 300°C and nanoencapsulated oil showed higher stability against oxidation than unencapsulated oil. The results suggest that chia seed mucilage represents a promising alternative to substitute synthetic polymers in nanoencapsulation.